Moses V. Chao, Ph.D.

A cell culture model of facial palsy resulting from reactivation of latent herpes simplex type 1
Kuhn, Maggie A; Nayak, Shruti; Camarena, Vladimir; Gardner, Jimmy; Wilson, Angus; Mohr, Ian; Chao, Moses V; Roehm, Pamela C
2012 Jan;33(1):87-92, Otology & neurotology
HYPOTHESIS: Reactivation of herpes simplex virus type 1 (HSV-1) in geniculate ganglion neurons (GGNs) is an etiologic mechanism of Bell's palsy (BP) and delayed facial palsy (DFP) after otologic surgery. BACKGROUND: Several clinical studies, including temporal bone studies, antibody, titers, and intraoperative studies, suggest that reactivation of HSV-1 from latently infected GGNs may lead to both BP and DFP. However, it is difficult to study these processes in humans or live animals. METHODS: Primary cultures of GGNs were latently infected with Patton strain HSV-1 expressing a green fluorescent protein-late lytic gene chimera. Four days later, these cultures were treated with trichostatin A (TSA), a known chemical reactivator of HSV-1 in other neurons. Cultures were monitored daily by fluorescent microscopy. Titers of media from lytic, latent, and latent/TSA treated GGN cultures were obtained using plaque assays on Vero cells. RNA was harvested from latently infected GGN cultures and examined for the presence of viral transcripts using reverse transcription-polymerase chain reaction. RESULTS: Latently infected GGN cultures displayed latency-associated transcripts only, whereas lytically infected and reactivated latent cultures produced other viral transcripts, as well. The GGN cultures displayed a reactivation rate of 65% after treatment with TSA. Media from latently infected cultures contained no detectable infectious HSV-1, whereas infectious virus was observed in both lytically and latently infected/TSA-treated culture media. CONCLUSION: We have shown that cultured GGNs can be latently infected with HSV-1, and HSV-1 in these latently infected neurons can be reactivated using TSA, yielding infectious virus. These results have implications for the cause of both BP and DFP
— id: 146264, year: 2012, vol: 33, page: 87, stat: Journal Article,

Acetylcholinesterase inhibitors rapidly activate Trk neurotrophin receptors in the mouse hippocampus
Autio, Henri; Matlik, Kert; Rantamaki, Tomi; Lindemann, Lothar; Hoener, Marius C; Chao, Moses; Arumae, Urmas; Castren, Eero
2011 Dec;61(8):1291-1296, Neuropharmacology
Acetylcholinesterase inhibitors are first-line therapies for Alzheimer's disease. These drugs increase cholinergic tone in the target areas of the cholinergic neurons of the basal forebrain. Basal forebrain cholinergic neurons are dependent upon trophic support by nerve growth factor (NGF) through its neurotrophin receptor, TrkA. In the present study, we investigated whether the acetylcholinesterase inhibitors donepezil and galantamine could influence neurotrophin receptor signaling in the brain. Acute administration of donepezil (3 mg/kg, i.p.) led to the rapid autophosphorylation of TrkA and TrkB neurotrophin receptors in the adult mouse hippocampus. Similarly, galantamine dose-dependently (3, 9 mg/kg, i.p.) increased TrkA and TrkB phosphorylation in the mouse hippocampus. Both treatments also increased the phosphorylation of transcription factor CREB and tended to increase the phosphorylation of AKT kinase but did not alter the activity of MAPK42/44. Chronic treatment with galantamine (3 mg/kg, i.p., 14 days), did not induce changes in hippocampal NGF and BDNF synthesis or protein levels. Our findings show that acetylcholinesterase inhibitors are capable of rapidly activating hippocampal neurotrophin signaling and thus suggest that therapies targeting Trk signaling may already be in clinical use in the treatment of AD
— id: 139925, year: 2011, vol: 61, page: 1291, stat: Journal Article,

Spatial segregation of BDNF transcripts enables BDNF to differentially shape distinct dendritic compartments
Baj, Gabriele; Leone, Emiliano; Chao, Moses V; Tongiorgi, Enrico
2011 Oct 4;108(40):16813-16818, Proceedings of the National Academy of Sciences of the United States of America
BDNF is produced from many transcripts that display distinct subcellular localization, suggesting that spatially restricted effects occur as a function of genetic and physiological regulation. Different BDNF 5' splice variants give a restricted localization in the cell body or the proximal and distal compartments of dendrites; however, the functional consequences are not known. Silencing individual endogenous transcripts or overexpressing BDNF-GFP transcripts in cultured neurons demonstrated that whereas some transcripts (1 and 4) selectively affected proximal dendrites, others (2C and 6) affected distal dendrites. Moreover, segregation of BDNF transcripts resulted in a highly selective activation of the BDNF TrkB receptor. These studies indicate that spatial segregation of BDNF transcripts enables BDNF to differentially shape distinct dendritic compartments
— id: 145795, year: 2011, vol: 108, page: 16813, stat: Journal Article,

Identifying transient protein-protein interactions in EphB2 signaling by blue native PAGE and mass spectrometry
Darie, Costel C; Deinhardt, Katrin; Zhang, Guoan; Cardasis, Helene S; Chao, Moses V; Neubert, Thomas A
2011 Dec;11(23):4514-4528, Proteomics
Receptor tyrosine kinases (RTKs) are proteins that upon ligand stimulation undergo dimerization and autophosphorylation. Eph receptors (EphRs) are RTKs that are found in different cell types, from both tissues that are developing and from mature tissues, and play important roles in the development of the central nervous system and peripheral nervous system. EphRs also play roles in synapse formation, neural crest formation, angiogenesis and in remodeling the vascular system. Interaction of EphRs with their ephrin ligands lead to activation of signal transduction pathways and formation of many transient protein-protein interactions that ultimately leads to cytoskeletal remodeling. However, the sequence of events at the molecular level is not well understood. We used blue native PAGE and MS to analyze the transient protein-protein interactions that resulted from the stimulation of EphB2 receptors by their ephrinB1-Fc ligands. We analyzed the phosphotyrosine-containing protein complexes immunoprecipitated from the cell lysates of both unstimulated (-) and ephrinB1-Fc-stimulated (+) NG108 cells. Our experiments allowed us to identify many signaling proteins, either known to be part of EphB2 signaling or new for this pathway, which are involved in transient protein-protein interactions upon ephrinB1-Fc stimulation. These data led us to investigate the roles of proteins such as FAK, WAVEs and Nischarin in EphB2 signaling
— id: 145796, year: 2011, vol: 11, page: 4514, stat: Journal Article,

Neuronal growth cone retraction relies on proneurotrophin receptor signaling through rac
Deinhardt, Katrin; Kim, Taeho; Spellman, Daniel S; Mains, Richard E; Eipper, Betty A; Neubert, Thomas A; Chao, Moses V; Hempstead, Barbara L
2011 ;4(202):ra82-ra82, Science signaling
Growth of axons and dendrites is a dynamic process that involves guidance molecules, adhesion proteins, and neurotrophic factors. Although neurite extension is stimulated by the neurotrophin nerve growth factor (NGF), we found that the precursor of NGF, proNGF, induced acute collapse of growth cones of cultured hippocampal neurons. This retraction was initiated by an interaction between the p75 neurotrophin receptor (p75(NTR)) and the sortilin family member SorCS2 (sortilin-related VPS10 domain-containing receptor 2). Binding of proNGF to the p75(NTR)-SorCS2 complex induced growth cone retraction by initiating the dissociation of the guanine nucleotide exchange factor Trio from the p75(NTR)-SorCS2 complex, resulting in decreased Rac activity and, consequently, growth cone collapse. The actin-bundling protein fascin was also inactivated, contributing to the destabilization and collapse of actin filaments. These results identify a bifunctional signaling mechanism by which proNGF regulates actin dynamics to acutely modulate neuronal morphology
— id: 146263, year: 2011, vol: 4, page: ra82, stat: Journal Article,

A selective role for ARMS/Kidins220 scaffold protein in spatial memory and trophic support of entorhinal and frontal cortical neurons
Duffy, Aine M; Schaner, Michael J; Wu, Synphen H; Staniszewski, Agnieszka; Kumar, Asok; Arevalo, Juan Carlos; Arancio, Ottavio; Chao, Moses V; Scharfman, Helen E
2011 Jun;229(2):409-420, Experimental neurology
Progressive cortical pathology is common to several neurodegenerative and psychiatric disorders. The entorhinal cortex (EC) and frontal cortex (FC) are particularly vulnerable, and neurotrophins have been implicated because they appear to be protective. A downstream signal transducer of neurotrophins, the ankyrin repeat-rich membrane spanning scaffold protein/Kidins 220 (ARMS) is expressed in the cortex, where it could play an important role in trophic support. To test this hypothesis, we evaluated mice with a heterozygous deletion of ARMS (ARMS(+/-) mice). Remarkably, the EC and FC were the regions that demonstrated the greatest defects. Many EC and FC neurons became pyknotic in ARMS(+/-) mice, so that large areas of the EC and FC were affected by 12 months of age. Areas with pyknosis in the EC and FC of ARMS(+/-) mice were also characterized by a loss of immunoreactivity to a neuronal antigen, NeuN, which has been reported after insult or injury to cortical neurons. Electron microscopy showed that there were defects in mitochondria, myelination, and multilamellar bodies in the EC and FC of ARMS(+/-) mice. Although primarily restricted to the EC and FC, pathology appeared to be sufficient to cause functional impairments, because ARMS(+/-) mice performed worse than wild-type on the Morris water maze. Comparisons of males and females showed that female mice were the affected sex in all comparisons. Taken together, the results suggest that the expression of a prominent neurotrophin receptor substrate normally protects the EC and FC, and that ARMS may be particularly important in females
— id: 145797, year: 2011, vol: 229, page: 409, stat: Journal Article,

TrkB as a Potential Synaptic and Behavioral Tag
Lu, Yuan; Ji, Yuanyuan; Ganesan, Sundar; Schloesser, Robert; Martinowich, Keri; Sun, Mu; Mei, Fan; Chao, Moses V; Lu, Bai
2011 Aug 17;31(33):11762-11771, Journal of neuroscience
Late-phase long-term potentiation (L-LTP), a cellular model for long-term memory (LTM), requires de novo protein synthesis. An attractive hypothesis for synapse specificity of long-term memory is 'synaptic tagging': synaptic activity generates a tag, which 'captures' the PRPs (plasticity-related proteins) derived outside of synapses. Here we provide evidence that TrkB, the receptor of BDNF (brain-derived neurotrophic factor), may serve as a 'synaptic tag.' TrkB is transiently activated by weak theta-burst stimulation (TBS) that induces only early-phase LTP (E-LTP). This TrkB activation is independent of protein synthesis, and confined to stimulated synapses. Induction of L-LTP by strong stimulation in one synaptic pathway converts weak TBS-induced E-LTP to L-LTP in a second, independent pathway. Transient inhibition of TrkB around the time of weak TBS to the second pathway diminished L-LTP in that pathway without affecting the first one. Behaviorally, weak training, which induces short-term memory (STM) but not LTM, can be consolidated into LTM by exposing animals to novel but not familiar environment 1 h before training. Inhibition of TrkB during STM training blocked such consolidation. These results suggest TrkB as a potential tag for synapse-specific expression of L-LTP and LTM
— id: 136649, year: 2011, vol: 31, page: 11762, stat: Journal Article,

Huntingtin mediates dendritic transport of I<super>2</super>-actin mRNA in rat neurons
Ma B; Savas JN; Yu M-S; Culver BP; Chao MV; Tanese N
2011 Nov;1:140-?, Scientific reports
— id: 150540, year: 2011, vol: 1, page: 140, stat: Journal Article,

APP is Phosphorylated by TrkA and Regulates NGF/TrkA Signaling
Matrone, Carmela; Barbagallo, Alessia P M; La Rosa, Luca R; Florenzano, Fulvio; Ciotti, Maria T; Mercanti, Delio; Chao, Moses V; Calissano, Pietro; D'Adamio, Luciano
2011 Aug 17;31(33):11756-11761, Journal of neuroscience
The pathogenic model of Alzheimer's disease (AD) posits that aggregates of amyloid beta, a product of amyloid precursor protein (APP) processing, cause dementia. However, alterations of normal APP functions could contribute to AD pathogenesis, and it is therefore important to understand the role of APP. APP is a member of a gene family that shows functional redundancy as documented by the evidence that single knock-out mice are viable, whereas mice with combined deletions of APP family genes die shortly after birth. A residue in the APP intracellular region, Y(682), is indispensable for these essential functions of APP. It is therefore important to identify pathways that regulate phosphorylation of Y(682) as well as the role of Y(682) in vivo. TrkA is associated with both phosphorylation of APP-Y(682) and alteration of APP processing, suggesting that tyrosine phosphorylation of APP links APP processing and neurotrophic signaling to intracellular pathways associated with cellular differentiation and survival. Here we have tested whether the NGF/TrkA signaling pathway is a physiological regulator of APP phosphorylation. We find that NGF induces tyrosine phosphorylation of APP, and that APP interacts with TrkA and this interaction requires Y(682). Unpredictably, we also uncover that APP, and specifically Y(682), regulates activation of the NGF/TrkA signaling pathway in vivo, the subcellular distribution of TrkA and the sensitivity of neurons to the trophic action of NGF. This evidence suggests that these two membrane protein's functions are strictly interconnected and that the NGF/TrkA signaling pathway is involved in AD pathogenesis and can be used as a therapeutic target
— id: 136648, year: 2011, vol: 31, page: 11756, stat: Journal Article,

Cultured vestibular ganglion neurons demonstrate latent HSV1 reactivation
Roehm, Pamela C; Camarena, Vladimir; Nayak, Shruti; Gardner, James B; Wilson, Angus; Mohr, Ian; Chao, Moses V
2011 Oct;121(10):2268-2275, Laryngoscope
OBJECTIVES/HYPOTHESIS: Vestibular neuritis is a common cause of both acute and chronic vestibular dysfunction. Multiple pathologies have been hypothesized to be the causative agent of vestibular neuritis; however, whether herpes simplex type I (HSV1) reactivation occurs within the vestibular ganglion has not been demonstrated previously by experimental evidence. We developed an in vitro system to study HSV1 infection of vestibular ganglion neurons (VGNs) using a cell culture model system. STUDY DESIGN: basic science study. RESULTS: Lytic infection of cultured rat VGNs was observed following low viral multiplicity of infection (MOI). Inclusion of acyclovir suppressed lytic replication and allowed latency to be established. Upon removal of acyclovir, latent infection was confirmed with reverse-transcription polymerase chain reaction and by RNA fluorescent in situ hybridization for the latency-associated transcript (LAT). A total of 29% cells in latently infected cultures were LAT positive. The lytic ICP27 transcript was not detected by reverse-transcription polymerase chain reaction (RT-PCR). Reactivation of HSV1 occurred at a high frequency in latently infected cultures following treatment with trichostatin A (TSA), a histone deactylase inhibitor. CONCLUSIONS: VGNs can be both lytically and latently infected with HSV1. Furthermore, latently infected VGNs can be induced to reactivate using TSA. This demonstrates that reactivation of latent HSV1 infection in the vestibular ganglion can occur in a cell culture model, and suggests that reactivation of HSV1 infection a plausible etiologic mechanism of vestibular neuritis
— id: 137886, year: 2011, vol: 121, page: 2268, stat: Journal Article,

Paranodal permeability in "myelin mutants"
Shroff, Seema; Mierzwa, Amanda; Scherer, Steven S; Peles, Elior; Arevalo, Juan C; Chao, Moses V; Rosenbluth, Jack
2011 Oct;59(10):1447-1457, Glia
Fluorescent dextran tracers of varying sizes have been used to assess paranodal permeability in myelinated sciatic nerve fibers from control and three 'myelin mutant' mice, Caspr-null, cst-null, and shaking. We demonstrate that in all of these the paranode is permeable to small tracers (3 kDa and 10 kDa), which penetrate most fibers, and to larger tracers (40 kDa and 70 kDa), which penetrate far fewer fibers and move shorter distances over longer periods of time. Despite gross diminution in transverse bands (TBs) in the Caspr-null and cst-null mice, the permeability of their paranodal junctions is equivalent to that in controls. Thus, deficiency of TBs in these mutants does not increase the permeability of their paranodal junctions to the dextrans we used, moving from the perinodal space through the paranode to the internodal periaxonal space. In addition, we show that the shaking mice, which have thinner myelin and shorter paranodes, show increased permeability to the same tracers despite the presence of TBs. We conclude that the extent of penetration of these tracers does not depend on the presence or absence of TBs but does depend on the length of the paranode and, in turn, on the length of 'pathway 3,' the helical extracellular pathway that passes through the paranode parallel to the lateral edge of the myelin sheath. (c) 2011 Wiley-Liss, Inc
— id: 135571, year: 2011, vol: 59, page: 1447, stat: Journal Article,

Distribution of Phosphorylated TrkB Receptor in the Mouse Hippocampal Formation Depends on Sex and Estrous Cycle Stage
Spencer-Segal, Joanna L; Waters, Elizabeth M; Bath, Kevin G; Chao, Moses V; McEwen, Bruce S; Milner, Teresa A
2011 May 4;31(18):6780-6790, Journal of neuroscience
Tropomyosin-related kinase B receptor (TrkB) is a neurotrophin receptor important for the synaptic plasticity underlying hippocampal-dependent learning and memory. Because this receptor is widely expressed in hippocampal neurons, the precise location of TrkB activation is likely important for its specific actions. The goal of this study was to identify the precise sites of TrkB activation in the mouse hippocampal formation and to determine any changes in the distribution of activated TrkB under conditions of enhanced brain-derived neurotrophic factor (BDNF) expression and hippocampal excitability. Using electron microscopy, we localized TrkB phosphorylated at tyrosine 816 (pTrkB) in the hippocampal formation of male and female mice under conditions of naturally low circulating estradiol and naturally high circulating estradiol, when BDNF expression, TrkB signaling, and synaptic plasticity are enhanced. To compare relative amounts of pTrkB in each group, we counted profiles containing pTrkB-immunoreactivity (pTrkB-ir) in all hippocampal subregions. pTrkB-ir was in axons, axon terminals, dendrites, and dendritic spines of neurons in the hippocampal formation, but the majority of pTrkB-ir localized to presynaptic profiles. pTrkB-ir also was abundant in glial profiles, which were further identified as microglia using immunofluorescence and confocal microscopy. Axonal and glial pTrkB-ir and pTrkB-ir in the CA1 stratum radiatum were more abundant in high-estradiol states (proestrus females) than low-estradiol states (estrus and diestrus females and males). These findings suggest that presynaptic TrkB is positioned to modulate estradiol-mediated and BDNF-dependent synaptic plasticity. Furthermore, they suggest a novel role for TrkB in microglial function in the neuroimmune system
— id: 131976, year: 2011, vol: 31, page: 6780, stat: Journal Article,

Sortilin associates with Trk receptors to enhance anterograde transport and neurotrophin signaling
Vaegter, Christian B; Jansen, Pernille; Fjorback, Anja W; Glerup, Simon; Skeldal, Sune; Kjolby, Mads; Richner, Mette; Erdmann, Bettina; Nyengaard, Jens R; Tessarollo, Lino; Lewin, Gary R; Willnow, Thomas E; Chao, Moses V; Nykjaer, Anders
2011 Jan;14(1):54-61, Nature neuroscience
Binding of target-derived neurotrophins to Trk receptors at nerve terminals is required to stimulate neuronal survival, differentiation, innervation and synaptic plasticity. The distance between the soma and nerve terminal is great, making efficient anterograde Trk transport critical for Trk synaptic translocation and signaling. The mechanism responsible for this trafficking remains poorly understood. Here we show that the sorting receptor sortilin interacts with TrkA, TrkB and TrkC and enables their anterograde axonal transport, thereby enhancing neurotrophin signaling. Cultured DRG neurons lacking sortilin showed blunted MAP kinase signaling and reduced neurite outgrowth upon stimulation with NGF. Moreover, deficiency for sortilin markedly aggravated TrkA, TrkB and TrkC phenotypes present in p75(NTR) knockouts, and resulted in increased embryonic lethality and sympathetic neuropathy in mice heterozygous for TrkA. Our findings demonstrate a role for sortilin as an anterograde trafficking receptor for Trk and a positive modulator of neurotrophin-induced neuronal survival
— id: 122282, year: 2011, vol: 14, page: 54, stat: Journal Article,

Regulation of trafficking of activated TrkA is critical for NGF-mediated functions
Yu, Tao; Calvo, Laura; Anta, Begona; Lopez-Benito, Saray; Southon, Eileen; Chao, Moses V; Tessarollo, Lino; Arevalo, Juan C
2011 Apr;12(4):521-534, Traffic
Upon activation by nerve growth factor (NGF), TrkA is internalized, trafficked and sorted through different endosomal compartments. Proper TrkA trafficking and sorting are crucial events as alteration of these processes hinders NGF-mediated functions. However, it is not fully known which proteins are involved in the trafficking and sorting of TrkA. Here we report that Nedd4-2 regulates the trafficking of TrkA and NGF functions in sensory neurons. Depletion of Nedd4-2 disrupts the correct sorting of activated TrkA at the early and late endosome stages, resulting in an accumulation of TrkA in these compartments and, as a result of the reduced trafficking to the degradative pathway, TrkA is either reverted to the cell surface through the recycling pathway or retrogradely transported to the cell body. In addition, Nedd4-2 depletion enhances TrkA signaling and the survival of NGF-dependent dorsal root ganglion neurons, but not those of brain-derived neurotrophic factor-dependent neurons. Furthermore, neurons from a knock-in mouse expressing a TrkA mutant that does not bind Nedd4-2 protein exhibit increased NGF-mediated signaling and cell survival. Our data indicate that TrkA trafficking and sorting are regulated by Nedd4-2 protein
— id: 133179, year: 2011, vol: 12, page: 521, stat: Journal Article,

Study of Neurotrophin-3 Signaling in Primary Cultured Neurons using Multiplex Stable Isotope Labeling with Amino Acids in Cell Culture
Zhang, Guoan; Deinhardt, Katrin; Chao, Moses V; Neubert, Thomas A
2011 May 6;10(5):2546-2554, Journal of proteome research
Conventional stable isotope labeling with amino acids in cell culture (SILAC) requires extensive metabolic labeling of proteins and therefore is difficult to apply to cells that do not divide or are unstable in SILAC culture. Using two different sets of heavy amino acids for labeling allows for straightforward SILAC quantitation using partially labeled cells because the two cell populations are always equally labeled. Here we report the application of this labeling strategy to primary cultured neurons. We demonstrated that protein quantitation was not compromised by incomplete labeling of the neuronal proteins. We used this method to study neurotrophin-3 (NT-3) signaling in primary cultured neurons. Surprisingly our results indicate TrkB signaling is a major component of the signaling network induced by NT-3 in cortical neurons. In addition, involvement of proteins such as VAMP2, Scamp1, and Scamp3 suggests that NT-3 may lead to enhanced exocytosis of synaptic vesicles
— id: 132309, year: 2011, vol: 10, page: 2546, stat: Journal Article,

SIRT1 Regulates Thyroid-Stimulating Hormone Release by Enhancing PIP5Kgamma Activity through Deacetylation of Specific Lysine Residues in Mammals
Akieda-Asai, Sayaka; Zaima, Nobuhiro; Ikegami, Koji; Kahyo, Tomoaki; Yao, Ikuko; Hatanaka, Takahiro; Iemura, Shun-Ichiro; Sugiyama, Rika; Yokozeki, Takeaki; Eishi, Yoshinobu; Koike, Morio; Ikeda, Kyoji; Chiba, Takuya; Yamaza, Haruyoshi; Shimokawa, Isao; Song, Si-Young; Matsuno, Akira; Mizutani, Akiko; Sawabe, Motoji; Chao, Moses V; Tanaka, Masashi; Kanaho, Yasunori; Natsume, Tohru; Sugimura, Haruhiko; Date, Yukari; McBurney, Michael W; Guarente, Leonard; Setou, Mitsutoshi
2010 ;5(7):e11755-e11755, PLoS ONE
BACKGROUND: SIRT1, a NAD-dependent deacetylase, has diverse roles in a variety of organs such as regulation of endocrine function and metabolism. However, it remains to be addressed how it regulates hormone release there. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report that SIRT1 is abundantly expressed in pituitary thyrotropes and regulates thyroid hormone secretion. Manipulation of SIRT1 level revealed that SIRT1 positively regulated the exocytosis of TSH-containing granules. Using LC/MS-based interactomics, phosphatidylinositol-4-phosphate 5-kinase (PIP5K)gamma was identified as a SIRT1 binding partner and deacetylation substrate. SIRT1 deacetylated two specific lysine residues (K265/K268) in PIP5Kgamma and enhanced PIP5Kgamma enzyme activity. SIRT1-mediated TSH secretion was abolished by PIP5Kgamma knockdown. SIRT1 knockdown decreased the levels of deacetylated PIP5Kgamma, PI(4,5)P(2), and reduced the secretion of TSH from pituitary cells. These results were also observed in SIRT1-knockout mice. CONCLUSIONS/SIGNIFICANCE: Our findings indicated that the control of TSH release by the SIRT1-PIP5Kgamma pathway is important for regulating the metabolism of the whole body
— id: 134327, year: 2010, vol: 5, page: e11755, stat: Journal Article,

The ARMS/Kidins220 scaffold protein modulates synaptic transmission
Arevalo, Juan Carlos; Wu, Synphen H; Takahashi, Takuya; Zhang, Hong; Yu, Tao; Yano, Hiroko; Milner, Teresa A; Tessarollo, Lino; Ninan, Ipe; Arancio, Ottavio; Chao, Moses V
2010 Oct;45(2):92-100, Molecular & cellular neurosciences
Activity-dependent changes of synaptic connections are facilitated by a variety of scaffold proteins, including PSD-95, Shank, SAP97 and GRIP, which serve to organize ion channels, receptors and enzymatic activities and to coordinate the actin cytoskeleton. The abundance of these scaffold proteins raises questions about the functional specificity of action of each protein. Here we report that basal synaptic transmission is regulated in an unexpected manner by the ankyrin repeat-rich membrane-spanning (ARMS/Kidins220) scaffold protein. In particular, decreases in the levels of ARMS/Kidins220 in vivo led to an increase in basal synaptic transmission in the hippocampus, without affecting paired pulse facilitation. One explanation to account for the effects of ARMS/Kidins220 is an interaction with the AMPA receptor subunit, GluA1, which could be observed after immunoprecipitation. Importantly, shRNA and cell surface biotinylation experiments indicate that ARMS/Kidins220 levels have an impact on GluA1 phosphorylation and localization. Moreover, ARMS/Kidins220 is a negative regulator of AMPAR function, which was confirmed by inward rectification assays. These results provide evidence that modulation of ARMS/Kidins220 levels can regulate basal synaptic strength in a specific manner in hippocampal neurons
— id: 111962, year: 2010, vol: 45, page: 92, stat: Journal Article,

Activation of Adenosine A2A Receptors Induces TrkB Translocation and Increases BDNF-Mediated Phospho-TrkB Localization in Lipid Rafts: Implications for Neuromodulation
Assaife-Lopes, Natalia; Sousa, Vasco C; Pereira, Daniela B; Ribeiro, Joaquim A; Chao, Moses V; Sebastiao, Ana M
2010 Jun 23;30(25):8468-8480, Journal of neuroscience
Brain-derived neurotrophic factor (BDNF) signaling is critical for neuronal development and transmission. Recruitment of TrkB receptors to lipid rafts has been shown to be necessary for the activation of specific signaling pathways and modulation of neurotransmitter release by BDNF. Since TrkB receptors are known to be modulated by adenosine A(2A) receptor activation, we hypothesized that activation of A(2A) receptors could influence TrkB receptor localization among different membrane microdomains. We found that adenosine A(2A) receptor agonists increased the levels of TrkB receptors in the lipid raft fraction of cortical membranes and potentiated BDNF-induced augmentation of phosphorylated TrkB levels in lipid rafts. Blockade of the clathrin-mediated endocytosis with monodansylcadaverine (100 mum) did not modify the effects of the A(2A) receptor agonists but significantly impaired BDNF effects on TrkB recruitment to lipid rafts. The effect of A(2A) receptor activation in TrkB localization was mimicked by 5 mum forskolin, an adenylyl cyclase activator. Also, it was blocked by the PKA inhibitors Rp-cAMPs and PKI-(14-22), and by the Src-family kinase inhibitor PP2. Moreover, removal of endogenous adenosine or disruption of lipid rafts reduced BDNF stimulatory effects on glutamate release from cortical synaptosomes. Lipid raft integrity was also required for the effects of BDNF on hippocampal long-term potentiation at CA1 synapses. Our data demonstrate, for the first time, a BDNF-independent recruitment of TrkB receptors to lipid rafts induced by activation of adenosine A(2A) receptors, with functional consequences for TrkB phosphorylation and BDNF-induced modulation of neurotransmitter release and hippocampal plasticity
— id: 110091, year: 2010, vol: 30, page: 8468, stat: Journal Article,

Nature and duration of growth factor signaling through receptor tyrosine kinases regulates HSV-1 latency in neurons
Camarena, Vladimir; Kobayashi, Mariko; Kim, Ju Youn; Roehm, Pamela; Perez, Rosalia; Gardner, James; Wilson, Angus C; Mohr, Ian; Chao, Moses V
2010 Oct 21;8(4):320-330, Cell Host & Microbe
Herpes simplex virus-1 (HSV-1) establishes life-long latency in peripheral neurons where productive replication is suppressed. While periodic reactivation results in virus production, the molecular basis of neuronal latency remains incompletely understood. Using a primary neuronal culture system of HSV-1 latency and reactivation, we show that continuous signaling through the phosphatidylinositol 3-kinase (PI3-K) pathway triggered by nerve growth factor (NGF)-binding to the TrkA receptor tyrosine kinase (RTK) is instrumental in maintaining latent HSV-1. The PI3-K p110alpha catalytic subunit, but not the beta or delta isoforms, is specifically required to activate 3-phosphoinositide-dependent protein kinase-1 (PDK1) and sustain latency. Disrupting this pathway leads to virus reactivation. EGF and GDNF, two other growth factors capable of activating PI3-K and PDK1 but that differ from NGF in their ability to persistently activate Akt, do not fully support HSV-1 latency. Thus, the nature of RTK signaling is a critical host parameter that regulates the HSV-1 latent-lytic switch
— id: 113951, year: 2010, vol: 8, page: 320, stat: Journal Article,

A conversation with Rita Levi-Montalcini
Chao, Moses V
2010 Mar 17;72:1-13, Annual review of physiology
— id: 133758, year: 2010, vol: 72, page: 1, stat: Journal Article,

Increasing the specificity of neurotrophic factors
Chao, Moses V
2010 Aug 3;107(31):13565-13566, Proceedings of the National Academy of Sciences of the United States of America
— id: 111654, year: 2010, vol: 107, page: 13565, stat: Journal Article,

Trophic factors: 50 years of growth
Chao, Moses V; Ip, Nancy Y
2010 Apr;70(5):269-270, Developmental Neurobiology
— id: 108793, year: 2010, vol: 70, page: 269, stat: Journal Article,

Transactivation of Trk receptors in spinal motor neurons
Domeniconi, Marco; Chao, Moses V
2010 Sep;25(9):1207-1213, Histology & histopathology
The neurotrophins are a family of trophic factors that have been shown to have neuroprotective effects after traumatic lesions of the nervous system and in animal models of neurodegenerative diseases. They mediate a broad spectrum of biological actions by interacting with tyrosine kinase receptors (Trk). While studies have demonstrated that neurotrophin administration may have beneficial effects, there were difficulties in delivering therapeutic quantities of these factors to spinal motor neurons. We now describe a strategy for applying transactivation of Trk receptors using small molecules, such as adenosine, which can penetrate the blood brain barrier and rescue motor neurons from cell death. Transactivation opens up the possibility of stimulating Trk receptors only in populations of neurons that co-express both Trk and adenosine receptors. We propose in this review to exploit transactivation to improve the survival of motor neurons in a transgenic mouse model of ALS and for other neurodegenerative diseases, such as Alzheimer's and Huntington's disease
— id: 145798, year: 2010, vol: 25, page: 1207, stat: Journal Article,

Microarray analysis of hippocampal CA1 neurons implicates early endosomal dysfunction during Alzheimer's disease progression
Ginsberg, Stephen D; Alldred, Melissa J; Counts, Scott E; Cataldo, Anne M; Neve, Rachael L; Jiang, Ying; Wuu, Joanne; Chao, Moses V; Mufson, Elliott J; Nixon, Ralph A; Che, Shaoli
2010 Nov 15;68(10):885-893, Biological psychiatry
BACKGROUND: Endocytic dysfunction and neurotrophin signaling deficits may underlie the selective vulnerability of hippocampal neurons during the progression of Alzheimer's disease (AD), although there is little direct in vivo and biochemical evidence to support this hypothesis. METHODS: Microarray analysis of hippocampal CA1 pyramidal neurons acquired via laser capture microdissection was performed using postmortem brain tissue. Validation was achieved using real-time quantitative polymerase chain reaction and immunoblot analysis. Mechanistic studies were performed using human fibroblasts subjected to overexpression with viral vectors or knockdown via small interference RNA. RESULTS: Expression levels of genes regulating early endosomes (rab5) and late endosomes (rab7) are selectively upregulated in homogeneous populations of CA1 neurons from individuals with mild cognitive impairment and AD. The levels of these genes are selectively increased as antemortem measures of cognition decline during AD progression. Hippocampal quantitative polymerase chain reaction and immunoblot analyses confirmed increased levels of these transcripts and their respective protein products. Elevation of select rab GTPases regulating endocytosis paralleled the downregulation of genes encoding the neurotrophin receptors TrkB and TrkC. Overexpression of rab5 in cells suppressed TrkB expression, whereas knockdown of TrkB expression did not alter rab5 levels, suggesting that TrkB downregulation is a consequence of endosomal dysfunction associated with elevated rab5 levels in early AD. CONCLUSIONS: These data support the hypothesis that neuronal endosomal dysfunction is associated with preclinical AD. Increased endocytic pathway activity, driven by elevated rab GTPase expression, may result in long-term deficits in hippocampal neurotrophic signaling and represent a key pathogenic mechanism underlying AD progression
— id: 114169, year: 2010, vol: 68, page: 885, stat: Journal Article,

The MAP kinase phosphatase MKP-1 regulates BDNF-induced axon branching
Jeanneteau, Freddy; Deinhardt, Katrin; Miyoshi, Goichi; Bennett, Anton M; Chao, Moses V
2010 Nov;13(11):1373-1379, Nature neuroscience
The refinement of neural circuits during development depends on a dynamic process of branching of axons and dendrites that leads to synapse formation and connectivity. The neurotrophin brain-derived neurotrophic factor (BDNF) is essential for the outgrowth and activity-dependent remodeling of axonal arbors in vivo. However, the mechanisms that translate extracellular signals into the formation of axonal branches are incompletely understood. We found that MAP kinase phosphatase-1 (MKP-1) controls axon branching. MKP-1 expression induced by BDNF signaling caused spatiotemporal deactivation of c-jun N-terminal kinase (JNK), which reduced the phosphorylation of JNK substrates that destabilize microtubules. Indeed, neurons from mkp-1 null mice could not produce axon branches in response to BDNF. Our results identify a signaling mechanism that regulates axonal branching and provide a framework for studying the molecular mechanisms of innervation and axonal remodeling under normal and pathological conditions
— id: 140038, year: 2010, vol: 13, page: 1373, stat: Journal Article,

Sciatic nerve injury model in the axolotl: functional, electrophysiological, and radiographic outcomes
Kropf, Nina; Krishnan, Kartik; Chao, Moses; Schweitzer, Mark; Rosenberg, Zehava; Russell, Stephen M
2010 Apr;112(4):880-889, Journal of neurosurgery
OBJECT: The 2 aims of this study were as follows: 1) to establish outcome measures of nerve regeneration in an axolotl model of peripheral nerve injury; and 2) to define the timing and completeness of reinnervation in the axolotl following different types of sciatic nerve injury. METHODS: The sciatic nerves in 36 axolotls were exposed bilaterally in 3 groups containing 12 animals each: Group 1, left side sham, right side crush; Group 2, left side sham, right side nerve resected and proximal stump buried; and Group 3 left side cut and sutured, right side cut and sutured with tibial and peroneal divisions reversed. Outcome measures included the following: 1) an axolotl sciatic functional index (ASFI) derived from video swim analysis; 2) motor latencies; and 3) MR imaging evaluation of nerve and muscle edema. RESULTS: For crush injuries, the ASFI returned to baseline by 2 weeks, as did MR imaging parameters and motor latencies. For buried nerves, the ASFI returned to 20% below baseline by 8 weeks, with motor evoked potentials present. On MR imaging, nerve edema peaked at 3 days postintervention and gradually normalized over 12 weeks, whereas muscle denervation was present until a gradual decrease was seen between 4 and 12 weeks. For cut nerves, the ASFI returned to 20% below baseline by Week 4, where it plateaued. Motor evoked potentials were observed at 2-4 weeks, but with an increased latency until Week 6, and MR imaging analysis revealed muscle denervation for 4 weeks. CONCLUSIONS: Multiple outcome measures in which an axolotl model of peripheral nerve injury is used have been established. Based on historical controls, recovery after nerve injury appears to occur earlier and is more complete than in rodents. Further investigation using this model as a successful 'blueprint' for nerve regeneration in humans is warranted
— id: 120633, year: 2010, vol: 112, page: 880, stat: Journal Article,

Localization of BDNF mRNA with the Huntington's disease protein in rat brain
Ma, Bin; Culver, Brady P; Baj, Gabriele; Tongiorgi, Enrico; Chao, Moses V; Tanese, Naoko
2010 ;5:22-22, Molecular neurodegeneration
ABSTRACT: BACKGROUND: Studies have implicated reduced levels of brain-derived neurotrophic factor (BDNF) in the pathogenesis of Huntington's disease. Mutant huntingtin (Htt) protein was previously reported to decrease BDNF gene transcription and axonal transport of BDNF. We recently showed that wild-type Htt is associated with the Argonaute 2 microRNA-processing enzyme involved in gene silencing. In dendrites, Htt co-localizes with components of neuronal granules and mRNAs, indicating that it might play a role in post-transcriptional processing/transport of dendritic mRNAs. RESULTS: We conducted imaging experiments in cultured cortical neurons to demonstrate the co-localization of endogenous Htt and BDNF mRNA in fixed cells, and co-trafficking of BDNF 3'UTR mRNA with endogenous and fluorescently tagged Htt in live neurons. We used an enhanced technique that combines FISH and immunofluorescent staining to co-localize BDNF mRNA with Htt, Ago2, CPEB and dynein in thick vibratome sections of the rat cortex. CONCLUSIONS: In cultured neurons and sections of the rat cortex, we found BDNF mRNA associated with Htt and components of neuronal RNA granules, which are centers for regulating RNA transport and local translation. Htt may play a role in post-transcriptional transport/targeting of mRNA for BDNF, thus contributing to neurotrophic support and neuron survival
— id: 110078, year: 2010, vol: 5, page: 22, stat: Journal Article,

Role of transverse bands in maintaining paranodal structure and axolemmal domain organization in myelinated nerve fibers: Effect on longevity in dysmyelinated mutant mice
Mierzwa, Amanda J; Arevalo, Juan-Carlos; Schiff, Rolf; Chao, Moses V; Rosenbluth, Jack
2010 Jul 15;518(14):2841-2853, Journal of comparative neurology
The consequences of dysmyelination are poorly understood and vary widely in severity. The shaking mouse, a quaking allele, is characterized by severe central nervous system (CNS) dysmyelination and demyelination, a conspicuous action tremor, and seizures in approximately 25% of animals, but with normal muscle strength and a normal lifespan. In this study we compare this mutant with other dysmyelinated mutants including the ceramide sulfotransferase deficient (CST-/-) mouse, which are more severely affected behaviorally, to determine what might underlie the differences between them with respect to behavior and longevity. Examination of the paranodal junctional region of CNS myelinated fibers shows that 'transverse bands,' a component of the junction, are present in nearly all shaking paranodes but in only a minority of CST-/- paranodes. The number of terminal loops that have transverse bands within a paranode and the number of transverse bands per unit length are only moderately reduced in the shaking mutant, compared with controls, but markedly reduced in CST-/- mice. Immunofluorescence studies also show that although the nodes of the shaking mutant are somewhat longer than normal, Na(+) and K(+) channels remain separated, distinguishing this mutant from CST-/- mice and others that lack transverse bands. We conclude that the essential difference between the shaking mutant and others more severely affected is the presence of transverse bands, which serve to stabilize paranodal structure over time as well as the organization of the axolemmal domains, and that differences in the prevalence of transverse bands underlie the marked differences in progressive neurological impairment and longevity among dysmyelinated mouse mutants. J. Comp. Neurol. 518:2841-2853, 2010. (c) 2010 Wiley-Liss, Inc
— id: 109814, year: 2010, vol: 518, page: 2841, stat: Journal Article,

The BDNF Val66Met polymorphism impairs NMDA receptor-dependent synaptic plasticity in the hippocampus
Ninan, Ipe; Bath, Kevin G; Dagar, Karishma; Perez-Castro, Rosalia; Plummer, Mark R; Lee, Francis S; Chao, Moses V
2010 Jun 30;30(26):8866-8870, Journal of neuroscience
The Val66Met polymorphism in the brain-derived neurotrophic factor (BDNF) gene results in a defect in regulated release of BDNF and affects episodic memory and affective behaviors. However, the precise role of the BDNF Val66Met polymorphism in hippocampal synaptic transmission and plasticity has not yet been studied. Therefore, we examined synaptic properties in the hippocampal CA3-CA1 synapses of BDNF(Met/Met) mice and matched wild-type mice. Although basal glutamatergic neurotransmission was normal, both young and adult mice showed a significant reduction in NMDA receptor-dependent long-term potentiation. We also found that NMDA receptor-dependent long-term depression was decreased in BDNF(Met/Met) mice. However, mGluR-dependent long-term depression was not affected by the BDNF Val66Met polymorphism. Consistent with the NMDA receptor-dependent synaptic plasticity impairment, we observed a significant decrease in NMDA receptor neurotransmission in the CA1 pyramidal neurons of BDNF(Met/Met) mice. Thus, these results show that the BDNF Val66Met polymorphism has a direct effect on NMDA receptor transmission, which may account for changes in synaptic plasticity in the hippocampus
— id: 110671, year: 2010, vol: 30, page: 8866, stat: Journal Article,

Ankyrin repeat-rich membrane spanning/Kidins220 protein interacts with mammalian Septin 5
Park, Han Jeong; Park, Hwan-Woo; Lee, Shin-Jae; Arevalo, Juan Carlos; Park, Young-Seok; Lee, Seung-Pyo; Paik, Ki-Suk; Chao, Moses V; Chang, Mi-Sook
2010 Aug;30(2):143-148, Molecules & cells
Neurotrophin receptors utilize specific adaptor proteins to activate signaling pathways involved in various neuronal functions, such as neurite outgrowth and cytoskeletal remodeling. The Ankyrin-Repeat Rich Membrane Spanning (ARMS)/kinase D-interacting substrate-220 kDa (Kidins220) serves as a unique downstream adaptor protein of Trk receptor tyrosine kinases. To gain insight into the role of ARMS/Kidins220, a yeast two-hybrid screen of a rat dorsal root ganglion library was performed using the C-terminal region of ARMS/Kidins220 as bait. The screen identified a mammalian septin, Septin 5 (Sept5), as an interacting protein. Co-immunoprecipitation using lysates from transiently transfected HEK-293 cells revealed the specific interaction between ARMS/Kidins220 and Sept5. Endogenous ARMS/Kidins220 and Sept5 proteins were colocalized in primary hippocampal neurons and were also predominantly expressed at the plasma membrane and in the tips of growing neurites in nerve growth factor-treated PC12 cells. Mapping of Sept5 domains important for ARMS/Kidins220 binding revealed a highly conserved N-terminal region of Sept5. The direct interaction between ARMS/Kidins220 and Sept5 suggests a possible role of ARMS/Kidins220 as a functional link between neurotrophin receptors and septins to mediate neurotrophin-induced intracellular signaling events, such as neurite outgrowth and cytoskeletal remodeling
— id: 138018, year: 2010, vol: 30, page: 143, stat: Journal Article,

Nuclear localization of the p75 neurotrophin receptor intracellular domain
Parkhurst, Christopher N; Zampieri, Niccolo; Chao, Moses V
2010 Feb 19;285(8):5361-5368, Journal of biological chemistry
The p75 neurotrophin receptor, a member of the tumor necrosis factor superfamily of receptors, undergoes an alpha-secretase-mediated release of its extracellular domain, followed by a gamma-secretase-mediated intramembrane cleavage. Like amyloid precursor protein and Notch, gamma-secretase cleavage of the p75 receptor releases an intracellular domain (ICD). However, it has been experimentally challenging to determine the precise subcellular localization and functional consequences of the p75 ICD. Here, we utilized a nuclear translocation assay and biochemical fractionation approaches to follow the fate of the ICD. We found that the p75 ICD can translocate to the nucleus to activate a green fluorescent protein reporter gene. Furthermore, the p75 ICD was localized in nuclear fractions. Chromatin immunoprecipitation experiments indicated that nerve growth factor induced the association of endogenous p75 with the cyclin E(1) promoter. Expression of the p75 ICD resulted in modulation of gene expression from this locus. These results suggest that the p75 ICD generated by gamma-secretase cleavage is capable of modulating transcriptional events in the nucleus
— id: 107370, year: 2010, vol: 285, page: 5361, stat: Journal Article,

Organophosphates induce distal axonal damage, but not brain oedema, by inactivating neuropathy target esterase
Read, David J; Li, Yong; Chao, Moses V; Cavanagh, John B; Glynn, Paul
2010 May 15;245(1):108-115, Toxicology & applied pharmacology
Single doses of organophosphorus compounds (OP) which covalently inhibit neuropathy target esterase (NTE) can induce lower-limb paralysis and distal damage in long nerve axons. Clinical signs of neuropathy are evident 3weeks post-OP dose in humans, cats and chickens. By contrast, clinical neuropathy in mice following acute dosing with OPs or any other toxic compound has never been reported. Moreover, dosing mice with ethyloctylphosphonofluoridate (EOPF) - an extremely potent NTE inhibitor - causes a different (subacute) neurotoxicity with brain oedema. These observations have raised the possibility that mice are intrinsically resistant to neuropathies induced by acute toxic insult, but may incur brain oedema, rather than distal axonal damage, when NTE is inactivated. Here we provide the first report that hind-limb dysfunction and extensive axonal damage can occur in mice 3weeks after acute dosing with a toxic compound, bromophenylacetylurea. Three weeks after acutely dosing mice with neuropathic OPs no clinical signs were observed, but distal lesions were present in the longest spinal sensory axons. Similar lesions were evident in undosed nestin-cre:NTEfl/fl mice in which NTE had been genetically-deleted from neural tissue. The extent of OP-induced axonal damage in mice was related to the duration of NTE inactivation and, as reported in chickens, was promoted by post-dosing with phenylmethanesulfonylfluoride. However, phenyldipentylphosphinate, another promoting compound in chickens, itself induced in mice lesions different from the neuropathic OP type. Finally, EOPF induced subacute neurotoxicity with brain oedema in both wild-type and nestin-cre:NTEfl/fl mice indicating that the molecular target for this effect is not neural NTE
— id: 145799, year: 2010, vol: 245, page: 108, stat: Journal Article,

A role for huntington disease protein in dendritic RNA granules
Savas, Jeffrey N; Ma, Bin; Deinhardt, Katrin; Culver, Brady P; Restituito, Sophie; Wu, Ligang; Belasco, Joel G; Chao, Moses V; Tanese, Naoko
2010 Apr 23;285(17):13142-13153, Journal of biological chemistry
Regulated transport and local translation of mRNA in neurons are critical for modulating synaptic strength, maintaining proper neural circuitry, and establishing long term memory. Neuronal RNA granules are ribonucleoprotein particles that serve to transport mRNA along microtubules and control local protein synthesis in response to synaptic activity. Studies suggest that neuronal RNA granules share similar structures and functions with somatic P-bodies. We recently reported that the Huntington disease protein huntingtin (Htt) associates with Argonaute (Ago) and localizes to cytoplasmic P-bodies, which serve as sites of mRNA storage, degradation, and small RNA-mediated gene silencing. Here we report that wild-type Htt associates with Ago2 and components of neuronal granules and co-traffics with mRNA in dendrites. Htt was found to co-localize with RNA containing the 3'-untranslated region sequence of known dendritically targeted mRNAs. Knockdown of Htt in neurons caused altered localization of mRNA. When tethered to a reporter construct, Htt down-regulated reporter gene expression in a manner dependent on Ago2, suggesting that Htt may function to repress translation of mRNAs during transport in neuronal granules
— id: 109209, year: 2010, vol: 285, page: 13142, stat: Journal Article,

Trk activation in the secretory pathway promotes Golgi fragmentation
Schecterson, Leslayann C; Hudson, Mark P; Ko, Mabel; Philippidou, Polyxeni; Akmentin, Wendy; Wiley, Jesse; Rosenblum, Elise; Chao, Moses V; Halegoua, Simon; Bothwell, Mark
2010 Apr;43(4):403-413, Molecular & cellular neurosciences
Activation of nascent receptor tyrosine kinases within the secretory pathway has been reported, yet the consequences of intracellular activation are largely unexplored. We report that overexpression of the Trk neurotrophin receptors causes accumulation of autoactivated receptors in the ER-Golgi intermediate compartment. Autoactivated receptors exhibit inhibited Golgi-mediated processing and they inhibit Golgi-mediated processing of other co-expressed transmembrane proteins, apparently by inducing fragmentation of the Golgi apparatus. Signaling from G protein-coupled receptors is known to induce Trk transactivation. Transactivation of nascent TrkB in hippocampal neurons resulting from exposure to the neuropeptide PACAP caused Golgi fragmentation, whereas BDNF-dependent activation of TrkB did not. TrkB-mediated Golgi fragmentation employs a MEK-dependent signaling pathway resembling that implicated in regulation of Golgi fragmentation in mitotic cells. Neuronal Golgi fragments, in the form of dendritically localized Golgi outposts, are important determinants of dendritic growth and branching. The capacity of transactivated TrkB to enhance neuronal Golgi fragmentation may represent a novel mechanism regulating neural plasticity
— id: 133480, year: 2010, vol: 43, page: 403, stat: Journal Article,

Regulation of inhibitory neurotransmission by the scaffolding protein ankyrin repeat-rich membrane spanning/kinase D-interacting substrate of 220 kDa
Sutachan, Jhon-Jairo; Chao, Moses V; Ninan, Ipe
2010 Dec;88(16):3447-56, Journal of neuroscience research
Scaffolding proteins play a critical role in the proper development and function of neural circuits. In contrast to the case for excitatory circuits, in which the role of several scaffolding proteins has been characterized, less is known about the scaffolding proteins that regulate inhibitory neurotransmission. The ankyrin repeat-rich membrane spanning (ARMS)/kinase D-interacting substrate of 220 kDa (Kidins220) scaffolding protein is expressed during the establishment of gamma-aminobutyric acid (GABA) neurotransmission and is highly regulated by activity. To evaluate whether ARMS/Kidins220 expression affects GABAergic neurotransmission, we modified the ARMS/Kidins220 levels during the period of its maximum expression in culture (DIV 1-10). Whereas a decrease in ARMS/Kidins220 levels suppressed GABAergic neurotransmission, overexpression of ARMS/Kidins220 produced an increase in GABAergic neurotransmission in hippocampal neurons. In addition, we found that ARMS/Kidins220 regulates GABAergic neurotransmission by a presynaptic mechanism. Our results suggest that the ARMS/Kidins220 scaffold protein plays a critical role in the regulation of inhibitory transmission in hippocampal neurons. (c) 2010 Wiley-Liss, Inc
— id: 114048, year: 2010, vol: 88, page: 3447, stat: Journal Article,

The ankyrin repeat-rich membrane spanning (ARMS)/Kidins220 scaffold protein is regulated by activity-dependent calpain proteolysis and modulates synaptic plasticity
Wu, Synphen H; Arevalo, Juan Carlos; Neubrand, Veronika E; Zhang, Hong; Arancio, Ottavio; Chao, Moses V
2010 Dec 24;285(52):40472-40478, Journal of biological chemistry
The expression of forms of synaptic plasticity, such as the phenomenon of long-term potentiation, requires the activity-dependent regulation of synaptic proteins and synapse composition. Here we show that ARMS (ankyrin repeat-rich membrane spanning protein)/Kidins220, a transmembrane scaffold molecule and BDNF TrkB substrate, is significantly reduced in hippocampal neurons after potassium chloride depolarization. The activity-dependent proteolysis of ARMS/Kidins220 was found to occur through calpain, a calcium-activated protease. Moreover, hippocampal long-term potentiation in ARMS/Kidins220(+/-) mice was enhanced, and inhibition of calpain in these mice reversed these effects. These results provide an explanation for a role for the ARMS/Kidins220 protein in synaptic plasticity events and suggest that the levels of ARMS/Kidins220 can be regulated by neuronal activity and calpain action to influence synaptic function
— id: 117336, year: 2010, vol: 285, page: 40472, stat: Journal Article,

Essential role of Hrs in endocytic recycling of full-length TrkB receptor but not its isoform TrkB.T1
Huang, Shu-Hong; Zhao, Ling; Sun, Zong-Peng; Li, Xue-Zhi; Geng, Zhao; Zhang, Kai-Di; Chao, Moses V; Chen, Zhe-Yu
2009 May 29;284(22):15126-15136, Journal of biological chemistry
Brain-derived neurotrophic factor (BDNF) signaling through its receptor, TrkB, modulates survival, differentiation, and synaptic activity of neurons. Both full-length TrkB (TrkB-FL) and its isoform T1 (TrkB.T1) receptors are expressed in neurons; however, whether they follow the same endocytic pathway after BDNF treatment is not known. In this study we report that TrkB-FL and TrkB.T1 receptors traverse divergent endocytic pathways after binding to BDNF. We provide evidence that in neurons TrkB.T1 receptors predominantly recycle back to the cell surface by a 'default' mechanism. However, endocytosed TrkB-FL receptors recycle to a lesser extent in a hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs)-dependent manner which relies on its tyrosine kinase activity. The distinct role of Hrs in promoting recycling of internalized TrkB-FL receptors is independent of its ubiquitin-interacting motif. Moreover, Hrs-sensitive TrkB-FL recycling plays a role in BDNF-induced prolonged mitogen-activated protein kinase (MAPK) activation. These observations provide evidence for differential postendocytic sorting of TrkB-FL and TrkB.T1 receptors to alternate intracellular pathways
— id: 145800, year: 2009, vol: 284, page: 15126, stat: Journal Article,

Neuroprotective effects of brain-derived neurotrophic factor in rodent and primate models of Alzheimer's disease
Nagahara, Alan H; Merrill, David A; Coppola, Giovanni; Tsukada, Shingo; Schroeder, Brock E; Shaked, Gideon M; Wang, Ling; Blesch, Armin; Kim, Albert; Conner, James M; Rockenstein, Edward; Chao, Moses V; Koo, Edward H; Geschwind, Daniel; Masliah, Eliezer; Chiba, Andrea A; Tuszynski, Mark H
2009 Mar;15(3):331-337, Nature medicine
Profound neuronal dysfunction in the entorhinal cortex contributes to early loss of short-term memory in Alzheimer's disease. Here we show broad neuroprotective effects of entorhinal brain-derived neurotrophic factor (BDNF) administration in several animal models of Alzheimer's disease, with extension of therapeutic benefits into the degenerating hippocampus. In amyloid-transgenic mice, BDNF gene delivery, when administered after disease onset, reverses synapse loss, partially normalizes aberrant gene expression, improves cell signaling and restores learning and memory. These outcomes occur independently of effects on amyloid plaque load. In aged rats, BDNF infusion reverses cognitive decline, improves age-related perturbations in gene expression and restores cell signaling. In adult rats and primates, BDNF prevents lesion-induced death of entorhinal cortical neurons. In aged primates, BDNF reverses neuronal atrophy and ameliorates age-related cognitive impairment. Collectively, these findings indicate that BDNF exerts substantial protective effects on crucial neuronal circuitry involved in Alzheimer's disease, acting through amyloid-independent mechanisms. BDNF therapeutic delivery merits exploration as a potential therapy for Alzheimer's disease
— id: 96166, year: 2009, vol: 15, page: 331, stat: Journal Article,

Neuropathy target esterase is required for adult vertebrate axon maintenance
Read, David J; Li, Yong; Chao, Moses V; Cavanagh, John B; Glynn, Paul
2009 Sep 16;29(37):11594-11600, Journal of neuroscience
The enzyme neuropathy target esterase (NTE) is present in neurons and deacylates the major membrane phospholipid, phosphatidylcholine (PtdCho). Mutation of the NTE gene or poisoning by neuropathic organophosphates-chemical inhibitors of NTE-causes distal degeneration of long spinal axons in humans. However, analogous neuropathological changes have not been reported in nestin-cre:NTEfl/fl mice with NTE-deficient neural tissue. Furthermore, altered PtdCho homeostasis has not been detected in NTE-deficient vertebrates. Here, we describe distal degeneration of the longest spinal axons in approximately 3-week-old nestin-cre:NTEfl/fl mice and in adult C57BL/6J mice after acute dosing with a neuropathic organophosphate: in both groups early degenerative lesions were followed by swellings comprising accumulated axoplasmic material. In mice dosed acutely with organophosphate, maximal numbers of lesions, in the longest spinal sensory axon tract, were attained within days and were preceded by a transient rise in neural PtdCho. In nestin-cre:NTEfl/fl mice, sustained elevation of PtdCho over many months was accompanied by progressive degeneration and massive swelling of axons in sensory and motor spinal tracts and by increasing hindlimb dysfunction. Axonal lesion distribution closely resembled that in hereditary spastic paraplegia (HSP). The importance of defective membrane trafficking in HSP and the association of NTE with the endoplasmic reticulum-the starting point for the constitutive secretory pathway and transport of neuronal materials into axons-prompted investigation for a role of NTE in secretion. Cultured NTE-deficient neurons displayed modestly impaired secretion, consistent with neuronal viability and damage in vivo initially restricted to distal parts of the longest axons
— id: 102412, year: 2009, vol: 29, page: 11594, stat: Journal Article,

Spongiform pathology in mouse CNS lacking 'neuropathy target esterase' and cellular prion protein
Rosenbluth, Jack; Schiff, Rolf; Lam, Pokman; Nuriel, Tal; Chao, Moses V
2009 Sep;35(3):433-437, Neurobiology of disease
Conditional inactivation of the 'neuropathy target esterase' (NTE) gene in mouse nerve cells was previously shown to result in CNS pathology comparable to the spongiform encephalopathy characteristic of prion diseases. To determine whether cellular prion protein (PrPc) is essential for development of this pathology we examined hippocampi of mice lacking NTE alone, PrPc alone or both NTE and PrPc. Light microscopic survey showed clear-cut spongiform changes in a majority of NTE-/- and NTE/PrP-/- double knockout mice but in only one PrP-/- mouse. EM analysis of spongiform lesions from NTE-/- and NTE/PrP-/- mice, and from the one affected PrP-/- mouse, revealed patches of branching tubular inclusions, comparable to the 'tubulovesicular inclusions' described previously in prion diseases. We conclude that spongiform pathology in conditional NTE knockout mice is not mediated by PrPc, and that tubulovesicular inclusions can be seen in spongiform encephalopathy of other etiologies and are not pathognomonic of prion disease
— id: 101443, year: 2009, vol: 35, page: 433, stat: Journal Article,

Ankyrin Repeat-rich Membrane Spanning/Kidins220 protein regulates dendritic branching and spine stability in vivo
Wu, Synphen H; Arevalo, Juan Carlos; Sarti, Federica; Tessarollo, Lino; Gan, Wen-Biao; Chao, Moses V
2009 Aug;69(9):547-557, Developmental Neurobiology
The development of nervous system connectivity depends upon the arborization of dendritic fields and the stabilization of dendritic spine synapses. It is well established that neuronal activity and the neurotrophin BDNF modulate these correlated processes. However, the downstream mechanisms by which these extrinsic signals regulate dendritic development and spine stabilization are less well known. Here we report that a substrate of BDNF signaling, the Ankyrin Repeat-rich Membrane Spanning (ARMS) protein or Kidins220, plays a critical role in the branching of cortical and hippocampal dendrites and in the turnover of cortical spines. In the barrel somatosensory cortex and the dentate gyrus, regions where ARMS/Kidins220 is highly expressed, no difference in the complexity of dendritic arbors was observed in 1-month-old adolescent ARMS/Kidins220(+/-) mice compared to wild-type littermates. However, at 3 months of age, young adult ARMS/Kidins220(+/-) mice exhibited decreased dendritic complexity. This suggests that ARMS/Kidins220 does not play a significant role in the initial formation of dendrites but, rather, is involved in the refinement or stabilization of the arbors later in development. In addition, at 1 month of age, the rate of spine elimination was higher in ARMS/Kidins220(+/-) mice than in wild-type mice, suggesting that ARMS/Kidins220(+/-) levels regulate spine stability. Taken together, these data suggest that ARMS/Kidins220 is important for the growth of dendritic arbors and spine stability during an activity- and BDNF-dependent period of development. (c) 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009
— id: 100607, year: 2009, vol: 69, page: 547, stat: Journal Article,

Proneurotrophin-3 is a neuronal apoptotic ligand: evidence for retrograde-directed cell killing
Yano, Hiroko; Torkin, Risa; Martin, Laura Andres; Chao, Moses V; Teng, Kenneth K
2009 Nov 25;29(47):14790-14802, Journal of neuroscience
Although mature neurotrophins are well described trophic factors that elicit retrograde survival signaling, the precursor forms of neurotrophins (i.e., proneurotrophins) can function as high-affinity apoptotic ligands for selected neural populations. An outstanding question is whether target-derived proneurotrophins might affect neuronal survival/death decisions through a retrograde transport mechanism. Since neurotrophin-3 (NT-3) is highly expressed in non-neural tissues that receive peripheral innervation, we investigated the localized actions of its precursor (proNT-3) on sympathetic neurons in the present study. Pharmacological inhibition of intracellular furin proteinase activity in 293T cells resulted in proNT-3 release instead of mature NT-3, whereas membrane depolarization in cerebellar granule neurons stimulated endogenous proNT-3 secretion, suggesting that proNT-3 is an inducible bona fide ligand in the nervous system. Our data also indicate that recombinant proNT-3 induced sympathetic neuron death that is p75(NTR)- and sortilin-dependent, with hallmark features of apoptosis including JNK (c-Jun N-terminal kinase) activation and nuclear fragmentation. Using compartmentalized culture systems that segregate neuronal cell bodies from axons, proNT-3, acting within the distal axon compartment, elicited sympathetic neuron death and overrode the survival-promoting actions of NGF. Together, these results raise the intriguing possibility that dysregulation of proneurotrophin processing/release by innervated targets can be deleterious to the neurons projecting to these sites
— id: 105519, year: 2009, vol: 29, page: 14790, stat: Journal Article,

Variant brain-derived neurotrophic factor (Val66Met) alters adult olfactory bulb neurogenesis and spontaneous olfactory discrimination
Bath, Kevin G; Mandairon, Nathalie; Jing, Deqiang; Rajagopal, Rithwick; Kapoor, Ruchi; Chen, Zhe-Yu; Khan, Tanvir; Proenca, Catia C; Kraemer, Rosemary; Cleland, Thomas A; Hempstead, Barbara L; Chao, Moses V; Lee, Francis S
2008 Mar 5;28(10):2383-2393, Journal of neuroscience
Neurogenesis, the division, migration, and differentiation of new neurons, occurs throughout life. Brain derived neurotrophic factor (BDNF) has been identified as a potential signaling molecule regulating neurogenesis in the subventricular zone (SVZ), but its functional consequences in vivo have not been well defined. We report marked and unexpected deficits in survival but not proliferation of newly born cells of adult knock-in mice containing a variant form of BDNF [a valine (Val) to methionine (Met) substitution at position 66 in the prodomain of BDNF (Val66Met)], a genetic mutation shown to lead to a selective impairment in activity-dependent BDNF secretion. Utilizing knock-out mouse lines, we identified BDNF and tyrosine receptor kinase B (TrkB) as the critical molecules for the observed impairments in neurogenesis, with p75 knock-out mice showing no effect on cell proliferation or survival. We then localized the activated form of TrkB to a discrete population of cells, type A migrating neuroblasts, and demonstrate a decrease in TrkB phosphorylation in the SVZ of Val66Met mutant mice. With these findings, we identify TrkB signaling, potentially through activity dependent release of BDNF, as a critical step in the survival of migrating neuroblasts. Utilizing a behavioral task shown to be sensitive to disruptions in olfactory bulb neurogenesis, we identified specific impairments in spontaneous olfactory discrimination, but not general olfactory sensitivity or habituation to olfactory stimuli in BDNF mutant mice. Through these observations, we have identified novel links between genetic variant BDNF and adult neurogenesis in vivo, which may contribute to significant impairments in olfactory function
— id: 77791, year: 2008, vol: 28, page: 2383, stat: Journal Article,

Growth factors and psychiatric disorders. Introduction
Chao, Moses
2008 ;289:1-3, Novartis foundation symposium
— id: 80614, year: 2008, vol: 289, page: 1, stat: Journal Article,

Neurotrophins : a window into brain function
Chao, Moses V
Dartmouth NH : Dartmouth College Media Production Group, 2008,
— id: 1628, year: 2008, vol: , page: , stat: ,

Dopamine D1 receptor-induced signaling through TrkB receptors in striatal neurons
Iwakura, Yuriko; Nawa, Hiroyuki; Sora, Ichiro; Chao, Moses V
2008 Jun 6;283(23):15799-15806, Journal of biological chemistry
In addition to its role as a neurotransmitter, dopamine can stimulate neurite outgrowth and morphological effects upon primary neurons. To investigate the signal transduction mechanisms used by dopamine in developing striatal neurons, we focused upon the effects of activating the dopamine D1 receptor. Using the D1 receptor agonist, SKF38393, we found that Trk neurotrophin receptors were activated in embryonic (E) day 18 striatal neurons. K-252a, a Trk tyrosine kinase inhibitor, and a dopamine D1 receptor antagonist could block the effects of SKF38393. The increase in TrkB phosphorylation was not the result of increased neurotrophin production. Induction of TrkB activity by D1 agonist was accompanied by the phosphorylation of several Trk signaling proteins, including PLCgamma, Akt and MAP kinase. Biotinylation experiments followed by immunostaining by phospho-TrkB specific antibodies indicated that the mechanism involved increased TrkB surface expression by dopamine D1 receptor activation. This increase in cell surface TrkB expression was dependent upon an increase in intracellular Ca2+. These results indicate that stimulation of dopamine D1 receptors can be coupled to the neurotrophin receptor signaling to mediate dopamine's effects upon striatal neurons
— id: 77789, year: 2008, vol: 283, page: 15799, stat: Journal Article,

Activation of Trk neurotrophin receptors by glucocorticoids provides a neuroprotective effect
Jeanneteau, Freddy; Garabedian, Michael J; Chao, Moses V
2008 Mar 25;105(12):4862-4867, Proceedings of the National Academy of Sciences of the United States of America
Glucocorticoids (GCs) display both protective and destructive effects in the nervous system. In excess, GCs produce neuronal damage after stress or brain injury; however, the neuroprotective effects of adrenal steroids also have been reported. The mechanisms that account for the positive actions are not well understood. Here we report that GCs can selectively activate Trk receptor tyrosine kinases after in vivo administration in the brain and in cultures of hippocampal and cortical neurons. Trk receptors are normally activated by neurotrophins, such as NGF and brain-derived neurotrophic factor, but the activation of Trk receptors by GCs does not depend on increased production of neurotrophins. Other tyrosine kinase receptors, such as EGF and FGF receptors, were not activated by GCs. The ability of GCs to increase Trk receptor activity resulted in the neuroprotection of neurons deprived of trophic support and could be modulated by steroid-converting enzymes. Pharmacological and shRNA experiments indicate that Trk receptor activation by GCs depends on a genomic action of the GC receptor. The ability of GCs to promote Trk receptor activity represents a molecular mechanism that integrates the actions of GCs and neurotrophins
— id: 77790, year: 2008, vol: 105, page: 4862, stat: Journal Article,

Neurotrophics and central nervous system development
Pereira, DB; Chao, MV
Handbook of neurochemistry and molecular neurobiology. Development and aging changes in the nervous system New York : Springer, 2008,
— id: 5495, year: 2008, vol: , page: ?, stat: Chapter,

Ankyrin-rich membrane spanning protein plays a critical role in nuclear factor-kappa B signaling
Sniderhan, Lynn F; Stout, Angela; Lu, Yuanan; Chao, Moses V; Maggirwar, Sanjay B
2008 Jul;38(3):404-416, Molecular & cellular neurosciences
Activation of nuclear factor-kappaB (NF-kappaB), a key feature of the neurotrophin signaling, has been shown to be critical for neuronal survival under pathologic settings. However, the precise mechanism by which neurotrophins activate NF-kappaB is not well understood. Here we report that the Ankyrin-rich Membrane Spanning (ARMS/Kidins220) protein, a novel transmembrane substrate of tropomyosin receptor kinase B (TrkB), plays an important role in NF-kappaB signaling elicited by brain-derived neurotrophic factor (BDNF). Accordingly, depletion of ARMS by specific RNA interference, or disruption of ARMS-TrkB interaction with expression of dominant-negative ARMS mutant, abolished BDNF-induced signaling to NF-kappaB. Our data further suggests that ARMS may promote NF-kappaB signaling via activation of mitogen-activated kinase (MAPK) and IkappaB kinase (IKK), thereby facilitating phosphorylation of RelA (major NF-kappaB subunit) at an IKK-sensitive site. The results shown here identify ARMS as a major factor that links neurotrophin signaling to NF-kappaB
— id: 96167, year: 2008, vol: 38, page: 404, stat: Journal Article,

Stable isotopic labeling of amino acids in cultured primary neurons: Application to BDNF-dependent phosphotyrosine-associated signaling
Spellman, Daniel S; Deinhardt, Katrin; Darie, Costel C; Chao, Moses V; Neubert, Thomas A
2008 Jun;7(6):1067-1076, Molecular & cellular proteomics
Cultured primary neurons are a well established model for the study of neuronal function in vitro. Here we have demonstrated that Stable Isotope Labeling by Amino Acids in Cell culture (SILAC) can be applied to a differentiated, non-dividing cell type such as primary neurons, and we have applied this technique to assess changes in the neuronal phosphotyrosine proteome in response to stimulation by BDNF (brain derived neurotrophic factor), an important molecule for the development and regulation of neuronal connections. We found that 13 proteins had SILAC ratios above 1.50 or below 0.67 in phosphotyrosine immunoprecipitates (pY IPs) comparing BDNF-treated and control samples, and an additional 18 proteins had ratios above 1.25 or below 0.80. These proteins include TrkB, the receptor tyrosine kinase (RTK) for BDNF, and others such as Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate) and STAM (signal-transducing adaptor molecule), which are proteins known to regulate intracellular trafficking of RTKs. These results demonstrate that the combination of primary neuronal cell culture and SILAC can be a powerful tool for the study of the proteomes of neuronal molecular and cellular dynamics
— id: 76648, year: 2008, vol: 7, page: 1067, stat: Journal Article,

Neurotrophins, synaptic plasticity and dementia
Arancio, Ottavio; Chao, Moses V
2007 Jun;17(3):325-330, Current opinion in neurobiology
The growing realization that neurotrophins, such as brain-derived neurotrophic factor (BDNF), are crucial in modulating synaptic plasticity has broadened the spectrum of their trophic actions. At the same time, it has become clear that Abeta peptides derived from amyloid precursor protein (APP) have dramatic effects on synaptic transmission before the onset of the neurodegenerative disease. Because neurotrophins and Abeta are responsible for affecting both synaptic and cognitive function, it is likely that their mechanisms of action will be related and might even intersect. This review highlights several recent findings that suggest trophic factors and APP use similar pathways to control neuronal activity
— id: 77794, year: 2007, vol: 17, page: 325, stat: Journal Article,

Retention of GluR1 receptors by ARMS/Kidins220 protein results in changes in synaptic activity
Arevalo, JC; Takahashi, T; Wu, SH; Chao, MV
2007 JUN ;101(18):48-49, Journal of neurochemistry
— id: 105083, year: 2007, vol: 101, page: 48, stat: Journal Article,

Neurotrophins: modes of action in health and disease
Chao, Moses
2007 ;:1-1 #P1, WCBG ... Abstract Book (World Congress on Psychiatric Genetics)
— id: 76058, year: 2007, vol: , page: 1, stat: Journal Article,

Developmental and activity-dependent regulation of ARMS/Kidins220 in cultured rat hippocampal neurons
Cortes, Rosa Y; Arevalo, Juan Carlos; Magby, Jason P; Chao, Moses V; Plummer, Mark R
2007 Nov;67(13):1687-1698, Developmental Neurobiology
Neurotrophin activation of Trk receptors elicits diverse effects on neuronal survival, differentiation, and synaptic plasticity. One of the central questions is how specificity is encoded in neurotrophin receptor signaling and actions. A unique downstream protein is the Ankyrin-Repeat Rich Membrane Spanning (ARMS)/Kinase D-interacting substrate-220 kDa (Kidins220), a very abundant scaffold protein in the hippocampus. To determine the roles of ARMS/Kidins220 in hippocampal neurons, we have analyzed the effects of synaptic activity upon the regulation and distribution of ARMS/Kidins220. At early times in vitro (<7 DIV), synaptic activity was low and ARMS/Kidins220 levels were high. As synaptic activity and markers for synapse maturation, such as PSD-95, increased, ARMS/Kidins220 significantly decreased to a plateau by later times in vitro (>12 DIV). Immunocytochemistry showed ARMS/Kidins220 to be concentrated at the tips of growing processes in immature cultures, and more diffusely distributed in older cultures. To examine the apparent inverse relationship between activity and ARMS/Kidins220 levels, neuronal firing was manipulated pharmacologically. Chronic exposure to TTX increased ARMS/Kidins220 levels, whereas bicuculline caused the opposite effect. Moreover, using shRNA to decrease ARMS/Kidins220 levels produced a corresponding increase in synaptic activity. We find that ARMS/Kidins220 may function in neuronal development as an indicator and potentially as a homeostatic regulator of overall synaptic strength in hippocampal neurons
— id: 77792, year: 2007, vol: 67, page: 1687, stat: Journal Article,

Pro-NGF secreted by astrocytes promotes motor neuron cell death
Domeniconi, Marco; Hempstead, Barbara L; Chao, Moses V
2007 Feb;34(2):271-279, Molecular & cellular neurosciences
It is well established that motor neurons depend for their survival on many trophic factors. In this study, we show that the precursor form of NGF (pro-NGF) can induce the death of motor neurons via engagement of the p75 neurotrophin receptor. The pro-apoptotic activity was dependent upon the presence of sortilin, a p75 co-receptor expressed on motor neurons. One potential source of pro-NGF is reactive astrocytes, which up-regulate the levels of pro-NGF in response to peroxynitrite, an oxidant and producer of free radicals. Indeed, motor neuron viability was sensitive to conditioned media from cultured astrocytes treated with peroxynitrite and this effect could be reversed using a specific antibody against the pro-domain of pro-NGF. These results are consistent with a role for activated astrocytes and pro-NGF in the induction of motor neuron death and suggest a possible therapeutic target for the treatment of motor neuron disease
— id: 71583, year: 2007, vol: 34, page: 271, stat: Journal Article,

The tyrosine kinase Fyn determines the localization of TrkB receptors in lipid rafts
Pereira, Daniela B; Chao, Moses V
2007 May 2;27(18):4859-4869, Journal of neuroscience
Localization of Trk neurotrophin receptors is an important factor in directing cellular communication in developing and mature neurons. One potential site of action is in lipid raft membrane microdomains. Although Trk receptors have been localized to lipid rafts, little is known about how these neurotrophin receptors are directed there or how localization to these membrane microdomains regulates Trk signaling. Here, we report that the TrkB brain-derived neurotrophic factor (BDNF) receptor specifically localized to intracellular lipid rafts in cortical and hippocampal membranes in response to BDNF and that this process was critically dependent on the tyrosine kinase Fyn. BDNF-induced TrkB accumulation at lipid rafts was prevented by blocking the internalization of TrkB. BDNF stimulation also resulted in the association between endogenous TrkB and Fyn. Moreover, in neurons derived from Fyn knock-out mice, the translocation of TrkB to lipid rafts in response to BDNF was compromised, whereas the corticohippocampal region of Fyn mutants displayed lower amounts of TrkB in lipid rafts in vivo. In support of a role for lipid rafts in neurotrophin signaling, inhibiting TrkB translocation to lipid rafts, either by using Fyn knock-out neurons or lipid raft-disturbing agents, prevented the full activation of TrkB and of downstream phospholipase C-gamma. These results indicate that the lipid raft localization of TrkB receptors is regulated by Fyn and represents an important factor in determining the outcome of BDNF signaling in neurons.
— id: 72820, year: 2007, vol: 27, page: 4859, stat: Journal Article,

Pharmacologically diverse antidepressants rapidly activate brain-derived neurotrophic factor receptor TrkB and induce phospholipase-Cgamma signaling pathways in mouse brain
Rantamaki, Tomi; Hendolin, Panu; Kankaanpaa, Aino; Mijatovic, Jelena; Piepponen, Petteri; Domenici, Enrico; Chao, Moses V; Mannisto, Pekka T; Castren, Eero
2007 Oct;32(10):2152-2162, Neuropsychopharmacology
Previous studies suggest that brain-derived neurotrophic factor and its receptor TrkB are critically involved in the therapeutic actions of antidepressant drugs. We have previously shown that the antidepressants imipramine and fluoxetine produce a rapid autophosphorylation of TrkB in the rodent brain. In the present study, we have further examined the biochemical and functional characteristics of antidepressant-induced TrkB activation in vivo. We show that all the antidepressants examined, including inhibitors of monoamine transporters and metabolism, activate TrkB rapidly in the rodent anterior cingulate cortex and hippocampus. Furthermore, the results indicate that acute and long-term antidepressant treatments induce TrkB-mediated activation of phospholipase-Cgamma1 (PLCgamma1) and increase the phosphorylation of cAMP-related element binding protein, a major transcription factor mediating neuronal plasticity. In contrast, we have not observed any modulation of the phosphorylation of TrkB Shc binding site, phosphorylation of mitogen-activated protein kinase or AKT by antidepressants. We also show that in the forced swim test, the behavioral effects of specific serotonergic antidepressant citalopram, but not those of the specific noradrenergic antidepressant reboxetine, are crucially dependent on TrkB signaling. Finally, brain monoamines seem to be critical mediators of antidepressant-induced TrkB activation, as antidepressants reboxetine and citalopram do not produce TrkB activation in the brains of serotonin- or norepinephrine-depleted mice. In conclusion, our data suggest that rapid activation of the TrkB neurotrophin receptor and PLCgamma1 signaling is a common mechanism for all antidepressant drugs
— id: 77795, year: 2007, vol: 32, page: 2152, stat: Journal Article,

Functional Interactions between the p75 neurotrophin receptor and phosphodiesterases
Sachs, B; Baillie, G; McCall, J; Schachtrup, C; Dunlop, A; MacKenzie, K; Klussman, E; Chao, M; Houslay, M; Akassoglou, K
2007 DEC ;2(6):S163-S163, Neuron glia biology
— id: 87176, year: 2007, vol: 2, page: S163, stat: Journal Article,

p75 neurotrophin receptor regulates tissue fibrosis through inhibition of plasminogen activation via a PDE4/cAMP/PKA pathway
Sachs, Benjamin D; Baillie, George S; McCall, Julianne R; Passino, Melissa A; Schachtrup, Christian; Wallace, Derek A; Dunlop, Allan J; MacKenzie, Kirsty F; Klussmann, Enno; Lynch, Martin J; Sikorski, Shoana L; Nuriel, Tal; Tsigelny, Igor; Zhang, Jin; Houslay, Miles D; Chao, Moses V; Akassoglou, Katerina
2007 Jun 18;177(6):1119-1132, Journal of cell biology
Clearance of fibrin through proteolytic degradation is a critical step of matrix remodeling that contributes to tissue repair in a variety of pathological conditions, such as stroke, atherosclerosis, and pulmonary disease. However, the molecular mechanisms that regulate fibrin deposition are not known. Here, we report that the p75 neurotrophin receptor (p75(NTR)), a TNF receptor superfamily member up-regulated after tissue injury, blocks fibrinolysis by down-regulating the serine protease, tissue plasminogen activator (tPA), and up-regulating plasminogen activator inhibitor-1 (PAI-1). We have discovered a new mechanism in which phosphodiesterase PDE4A4/5 interacts with p75(NTR) to enhance cAMP degradation. The p75(NTR)-dependent down-regulation of cAMP results in a decrease in extracellular proteolytic activity. This mechanism is supported in vivo in p75(NTR)-deficient mice, which show increased proteolysis after sciatic nerve injury and lung fibrosis. Our results reveal a novel pathogenic mechanism by which p75(NTR) regulates degradation of cAMP and perpetuates scar formation after injury
— id: 77793, year: 2007, vol: 177, page: 1119, stat: Journal Article,

Unique role of ARMS in neurotrophin-mediated activation of NF-kappa B and neuronal protection against HIV-1 encoded gp120
Sniderhan, LF; Ramirez, SH; Litzburg, A; Lu, YN; Chao, MV; Maggirwar, SB
2007 JAN ;13(1):125-125, Journal of neurovirology
— id: 75948, year: 2007, vol: 13, page: 125, stat: Journal Article,

TrkA receptor activation by nerve growth factor induces shedding of the p75 neurotrophin receptor followed by endosomal gamma-secretase-mediated release of the p75 intracellular domain
Urra, Soledad; Escudero, Claudia A; Ramos, Patricio; Lisbona, Fernanda; Allende, Edgardo; Covarrubias, Paulina; Parraguez, Jose I; Zampieri, Niccolo; Chao, Moses V; Annaert, Wim; Bronfman, Francisca C
2007 Mar 9;282(10):7606-7615, Journal of biological chemistry
Neurotrophins are trophic factors that regulate important neuronal functions. They bind two unrelated receptors, the Trk family of receptor-tyrosine kinases and the p75 neurotrophin receptor (p75). p75 was recently identified as a new substrate for gamma-secretase-mediated intramembrane proteolysis, generating a p75-derived intracellular domain (p75-ICD) with signaling capabilities. Using PC12 cells as a model, we studied how neurotrophins activate p75 processing and where these events occur in the cell. We demonstrate that activation of the TrkA receptor upon binding of nerve growth factor (NGF) regulates the metalloprotease-mediated shedding of p75 leaving a membrane-bound p75 C-terminal fragment (p75-CTF). Using subcellular fractionation to isolate a highly purified endosomal fraction, we demonstrate that p75-CTF ends up in endosomes where gamma-secretase-mediated p75-CTF cleavage occurs, resulting in the release of a p75-ICD. Moreover, we show similar structural requirements for gamma-secretase processing of p75 and amyloid precursor protein-derived CTFs. Thus, NGF-induced endocytosis regulates both signaling and proteolytic processing of p75
— id: 96168, year: 2007, vol: 282, page: 7606, stat: Journal Article,

Adenosine receptor A2A-R contributes to motoneuron survival by transactivating the tyrosine kinase receptor TrkB
Wiese, Stefan; Jablonka, Sibylle; Holtmann, Bettina; Orel, Nadiya; Rajagopal, Rithwick; Chao, Moses V; Sendtner, Michael
2007 Oct 23;104(43):17210-17215, Proceedings of the National Academy of Sciences of the United States of America
Neurotrophins are potent survival factors for developing and injured neurons. However, they are not being used to treat neurodegenerative diseases because of difficulties in administration and numerous side effects that have been encountered in previous clinical trials. Their biological activities use Trk (tropomyosin-related kinase) transmembrane tyrosine kinases. Therefore, one alternative approach is to use transactivation pathways such as adenosine 2A receptor agonists, which can activate Trk receptor signaling independent of neurotrophin binding. However, the relevance in vivo and applicability of these transactivation events during neurodegenerative and injury conditions have never been extensively studied. Here we demonstrate that motoneuron survival after facial nerve lesioning is significantly enhanced by transactivation of Trk receptor tyrosine kinases by adenosine agonists. Moreover, survival of motoneurons directly required the activation of the BDNF receptor TrkB and an increase in Akt (AKT8 virus oncogene cellular homolog) activity. The ability of small molecules to activate a trophic response by using Trk signaling provides a unique mechanism to promote survival signals in motoneurons and suggests new strategies for using transactivation in neurodegenerative diseases
— id: 75446, year: 2007, vol: 104, page: 17210, stat: Journal Article,

Molecular mechanisms of dentate gyrus granule cell resistance to seizure-induced damage
Wu, SH; Arevalo, JC; Malthankar-Phatak, GH; Hintz, TM; McCloskey, DP; Tessarollo, L; Chao, MV; Scharfman, HE
2007 OCT ;48(1):241-241, Epilepsia
— id: 87154, year: 2007, vol: 48, page: 241, stat: Journal Article,

Identification of a switch in neurotrophin signaling by selective tyrosine phosphorylation
Arevalo, Juan Carlos; Pereira, Daniela B; Yano, Hiroko; Teng, Kenneth K; Chao, Moses V
2006 Jan 13;281(2):1001-1007, Journal of biological chemistry
Neurotrophins, such as nerve growth factor and brain-derived neurotrophic factor, activate Trk receptor tyrosine kinases through receptor dimerization at the cell surface followed by autophosphorylation and recruitment of intracellular signaling molecules. The intracellular pathways used by neurotrophins share many common protein substrates that are used by other receptor tyrosine kinases (RTK), such as Shc, Grb2, FRS2, and phospholipase C-gamma. Here we describe a novel RTK mechanism that involves a 220-kilodalton membrane tetraspanning protein, ARMS/Kidins220, which is rapidly tyrosine phosphorylated in primary neurons after neurotrophin treatment. ARMS/Kidins220 undergoes multiple tyrosine phosphorylation events and also serine phosphorylation by protein kinase D. We have identified a single tyrosine (Tyr(1096)) phosphorylation event in ARMS/Kidins220 that plays a critical role in neurotrophin signaling. A reassembled complex of ARMS/Kidins220 and CrkL, an upstream component of the C3G-Rap1-MAP kinase cascade, is SH3-dependent. However, Tyr(1096) phosphorylation enables ARMS/Kidins220 to recruit CrkL through its SH2 domain, thereby freeing the CrkL SH3 domain to engage C3G for MAP kinase activation in a neurotrophin dependent manner. Accordingly, mutation of Tyr(1096) abolished CrkL interaction and sustained MAPK kinase activity, a response that is not normally observed in other RTKs. Therefore, Trk receptor signaling involves an inducible switch mechanism through an unconventional substrate that distinguishes neurotrophin action from other growth factor receptors
— id: 62638, year: 2006, vol: 281, page: 1001, stat: Journal Article,

Cell survival through Trk neurotrophin receptors is differentially regulated by ubiquitination
Arevalo, Juan Carlos; Waite, Janelle; Rajagopal, Rithwick; Beyna, Mercedes; Chen, Zhe-Yu; Lee, Francis S; Chao, Moses V
2006 May 18;50(4):549-559, Neuron
Specificity of neurotrophin factor signaling is dictated through the action of Trk receptor tyrosine kinases. Once activated, Trk receptors are internalized and targeted for degradation. However, the mechanisms implicated in this process are incompletely understood. Here we report that the Trk receptors are multimonoubiquitinated in response to neurotrophins. We have identified an E3 ubiquitin ligase, Nedd4-2, that associates with the TrkA receptor and is phosphorylated upon NGF binding. The binding of Nedd4-2 to TrkA through a PPXY motif leads to the ubiquitination and downregulation of TrkA. Activated TrkA receptor levels and the survival of NGF-dependent sensory neurons, but not BDNF-dependent sensory neurons, are directly influenced by Nedd4-2 expression. Unexpectedly, Nedd4-2 does not bind or ubiquitinate related TrkB receptors, due to the lack of a consensus PPXY motif. Our results indicate that Trk neurotrophin receptors are differentially regulated by ubiquitination to modulate the survival of neurons
— id: 64670, year: 2006, vol: 50, page: 549, stat: Journal Article,

Ira B. Black 1941-2006
Chao, Moses V
2006 Mar 2;49(5):653-654, Neuron
— id: 109680, year: 2006, vol: 49, page: 653, stat: Journal Article,

Neurotrophin signalling in health and disease
Chao, Moses V; Rajagopal, Rithwick; Lee, Francis S
2006 Feb;110(2):167-173, Clinical science (London, 1979)
Neurotrophins are a unique family of polypeptide growth factors that influence the proliferation, differentiation, survival and death of neuronal and non-neuronal cells. They are essential for the health and well-being of the nervous system. NGF (nerve growth factor), BDNF (brain-derived neurotrophic factor), NT-3 (neurotrophin-3) and NT-4 (neurotrophin-4) also mediate additional higher-order activities, such as learning, memory and behaviour, in addition to their established functions for cell survival. The effects of neurotrophins depend upon their levels of availability, their affinity of binding to transmembrane receptors and the downstream signalling cascades that are stimulated after receptor activation. Alterations in neurotrophin levels have been implicated in neurodegenerative disorders, such as Alzheimer's disease and Huntington's disease, as well as psychiatric disorders, including depression and substance abuse. Difficulties in administering trophic factors have led to the consideration of using small molecules, such as GPCR (G-protein-coupled receptor) ligands, which can participate in transactivation events. In this review, we consider the signalling pathways activated by neurotrophins in both health and disease states
— id: 64645, year: 2006, vol: 110, page: 167, stat: Journal Article,

ARMS interacts with alpha-syntrophin: Implications for EphA4 signaling at the neuromuscular synapse
Chen, Y; Luo, S; Lai, KO; Arevalo, JC; Froehner, SC; Adams, ME; Chao, MV; Ip, NY
2006 APR ;15(3):114-114, Neuro-signals
— id: 70619, year: 2006, vol: 15, page: 114, stat: Journal Article,

Promoting neurotrophic effects by GPCR ligands
Jeanneteau, Freddy; Chao, Moses V
2006 ;276:181-189, Novartis foundation symposium
The neurotrophins-nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT-3 and NT-4-represent a family of proteins essential for neuronal survival and plasticity. Each neurotrophin can signal through two different transmembrane receptors, Trk receptor tyrosine kinases and the p75 neurotrophin receptor, the first member of the TNF receptor superfamily. Neurotrophic factors play an important role in neurodegenerative diseases, as well as neuropsychiatric disorders such as depression, bipolar disease and eating disorders. Indeed, a number of approaches have been taken to use neurotrophins to treat Alzheimer's dementia, amyotrophic lateral sclerosis and peripheral sensory neuropathy. However, many of these clinical trails have failed, due to problems in delivery and unforeseen side effects of neurotrophic factors. An alternative approach is to use ligands in the G protein-coupled receptor (GPCR) family to transactivate trophic activities. We have discovered that treatment with adenosine, a neuromodulator that acts through G protein-coupled receptors, is capable of activating Trk tyrosine kinase receptors. Transactivation of neurotrophic receptors by GPCR ligands raise the possibility that small molecules may be used to elicit neurotrophic effects for the treatment of neurodegenerative diseases. This approach would allow for selective targeting of neurons that express specific G protein-coupled receptors and trophic factor receptors. GPCRs transduce information provided by extracellular signals to modulate synaptic activity and neurotransmission. In addition to the classical G protein signalling, GPCR ligands also activate receptor tyrosine kinases (RTK), including neurotrophin receptors. Activation of Trk neurotrophin receptors can occur by GPCR ligands in the absence of neurotrophins. Adenosine and PACAP (pituitary adenylate cyclase activating polypeptide) induce Trk activation specifically through their respective GPCRs to promote cell survival. Transactivation of Trks by GPCRs has emerged as a new theme in the biology of neurotrophin function. Although the precise role of transactivation is unknown, one possibility is that it adds a safety factor that might protect neurons from death in the absence of neurotrophins. Abnormal activity of the neurotrophin system has been implicated in several psychiatric and neurobiological illnesses. However, the lack of knowledge about the precise site of neurotrophin dysfunction has compromised the ability to improve the efficacy and the safety of drugs used in treatment modalities. If small-molecule GPCR ligands can ameliorate neuronal cell loss through Trk, transactivation may offer a new strategy for promoting trophic effects during neurodegeneration
— id: 66608, year: 2006, vol: 276, page: 181, stat: Journal Article,

Ligand-dependent cleavage of the P75 neurotrophin receptor is necessary for NRIF nuclear translocation and apoptosis in sympathetic neurons
Kenchappa, Rajappa S; Zampieri, Niccolo; Chao, Moses V; Barker, Philip A; Teng, Henry K; Hempstead, Barbara L; Carter, Bruce D
2006 Apr 20;50(2):219-232, Neuron
The p75 neurotrophin receptor regulates neuronal survival, promoting it in some contexts yet activating apoptosis in others. The mechanism by which the receptor elicits these differential effects is poorly understood. Here, we demonstrate that p75 is cleaved by gamma-secretase in sympathetic neurons, specifically in response to proapoptotic ligands. This cleavage resulted in ubiquitination and subsequent nuclear translocation of NRIF, a DNA binding protein essential for p75-mediated apoptosis. Inhibition of gamma-secretase or expression of a mutant p75 resistant to this protease prevented receptor proteolysis, blocked NRIF nuclear entry, and prevented apoptosis. In contrast, overexpression of the p75 ICD resulted in NRIF nuclear accumulation and apoptosis. The receptor proteolysis and NRIF nuclear localization were also observed in vivo during naturally occurring cell death in the superior cervical ganglia. These results indicate that p75-mediated apoptosis requires gamma-secretase dependent release of its ICD, which facilitates nuclear translocation of NRIF
— id: 66609, year: 2006, vol: 50, page: 219, stat: Journal Article,

Transactivation of TrkB receptor mediated by dopamine D1 receptor in developmental striatal neurons
Lwakura, Y; Chao, M
2006 SEP-OCT ;55(5):S115-S115, Neuroscience research
— id: 68831, year: 2006, vol: 55, page: S115, stat: Journal Article,

A role for Fyn in Trk receptor transactivation by G-protein-coupled receptor signaling
Rajagopal, Rithwick; Chao, Moses V
2006 Sep;33(1):36-46, Molecular & cellular neurosciences
Signaling through Trk receptor tyrosine kinases can occur in the absence of neurotrophins through certain G-protein-coupled receptors (GPCRs). It has previously been suggested that GPCR-mediated Trk activation occurs on intracellular membranes and involves several second messengers, including Src family kinases and intracellular calcium. Here, we describe a novel role for the Src family kinase, Fyn, in regulating signaling events between GPCRs and Trk. We find that Fyn expression is sufficient to allow transactivation of Trk by adenosine and that Fyn and Trk are colocalized in a juxtanuclear membrane compartment. Adenosine activation of Fyn results in direct phosphorylation of Trk in vitro and follows a delayed time course that coincides with Trk activation. These results indicate that Fyn is activated by GPCR stimulation and is responsible for transactivation of Trk receptors on intracellular membranes
— id: 66606, year: 2006, vol: 33, page: 36, stat: Journal Article,

BDNF gene delivery to the entorhinal cortex in models of Alzheimer's disease
Tuszynski, MH; Nagahara, AH; Merrill, DA; Tsukada, S; Schroeder, BE; Shaked, GM; Blesch, A; Kim, A; Conner, JM; Rockenstein, E; Chao, MV; Chiba, AA; Koo, E; Masliah, E
2006 FEB ;60(3):S8-S8, Annals of neurology
— id: 105084, year: 2006, vol: 60, page: S8, stat: Journal Article,

BDNF-mediated neurotransmission relies upon a myosin VI motor complex
Yano, Hiroko; Ninan, Ipe; Zhang, Hong; Milner, Teresa A; Arancio, Ottavio; Chao, Moses V
2006 Aug;9(8):1009-1018, Nature neuroscience
Brain-derived neurotrophic factor (BDNF) has been implicated in higher-order cognitive functions and in psychiatric disorders such as depression and schizophrenia. BDNF modulates synaptic transmission and plasticity primarily through the TrkB receptor, but the molecules involved in BDNF-mediated synaptic modulation are largely unknown. Myosin VI (Myo6) is a minus end-directed actin-based motor found in neurons that express Trk receptors. Here we report that Myo6 and a Myo6-binding protein, GIPC1, form a complex that can engage TrkB. Myo6 and GIPC1 were necessary for BDNF-TrkB-mediated facilitation of long-term potentiation in postnatal day 12-13 (P12-13) hippocampus. Moreover, BDNF-mediated enhancement of glutamate release from presynaptic terminals depended not only upon TrkB but also upon Myo6 and GIPC1. Similar defects in basal synaptic transmission as well as presynaptic properties were observed in Myo6 and GIPC1 mutant mice. Together, these results define an important role for the Myo6-GIPC1 motor complex in presynaptic function and in BDNF-TrkB-mediated synaptic plasticity
— id: 66607, year: 2006, vol: 9, page: 1009, stat: Journal Article,

Mechanisms of neurotrophin receptor signalling
Zampieri, N; Chao, M V
2006 Aug;34(Pt 4):607-611, Transactions (Biochemical Society (Great Britain))
Regulation of cell survival decisions and neuronal plasticity by neurotrophins are mediated by two classes of receptors, Trks (tropomyosin receptor kinases) and p75, the first discovered member of the tumour necrosis factor receptor superfamily. The p75 receptor participates with the TrkA receptor in the formation of high-affinity nerve growth factor-binding sites to promote survival under limiting concentrations of neurotrophins. Activation of Trk receptors leads to increased phosphorylation of Shc (Src homology and collagen homology), phospholipase C-gamma and novel adaptor molecules, such as the ARMS (ankyrin-rich membrane spanning)/Kidins220 protein. Small ligands that interact with G-protein-coupled receptors can also activate Trk receptor kinase activity. Transactivation of Trk receptors and their downstream signalling pathways raise the possibility of using small molecules to elicit neuroprotective effects for the treatment of neurodegenerative diseases. Like amyloid precursor protein and Notch, p75 is a substrate for gamma-secretase cleavage. The p75 receptor undergoes an alpha-secretase-mediated release of the extracellular domain followed by a gamma-secretase-mediated intramembrane cleavage. Cleavage of p75 may represent a general mechanism for transmitting signals as an independent receptor and as a co-receptor for other signalling systems
— id: 68629, year: 2006, vol: 34, page: 607, stat: Journal Article,

Axonal growth: where neurotrophins meet Wnts
Arevalo, Juan Carlos; Chao, Moses V
2005 Apr;17(2):112-115, Current opinion in cell biology
Axonal guidance is influenced by many cues, including polypeptide trophic factors, cytokines, diffusible attractants and repellents and changes in calcium. How these signals are conveyed and integrated is not well defined. Recent data suggest that molecules of the canonical Wnt signaling pathway may have direct actions on axonal growth through neurotrophin signaling. This surprising mechanism is supported by local inactivation of glycogen synthase kinase 3beta (GSK-3beta) by nerve growth factor through the integrin-linked kinase. Inhibition of GSK-3beta provides a positive regulatory signal for the cytoskeleton re-arrangement involved in axon extension. Moreover, microtubule stabilization is stimulated by adenomatous polyposis coli protein, a downstream target of GSK3, in response to neurotrophins. Therefore, components of the Wnt signaling pathway are downstream of trophic factors, providing new insights into cytoskeletal regulatory events during axonal growth
— id: 55999, year: 2005, vol: 17, page: 112, stat: Journal Article,

MAG induces regulated intramembrane proteolysis of the p75 neurotrophin receptor to inhibit neurite outgrowth
Domeniconi, Marco; Zampieri, Niccolo; Spencer, Tim; Hilaire, Melissa; Mellado, Wilfredo; Chao, Moses V; Filbin, Marie T
2005 Jun 16;46(6):849-855, Neuron
The three known inhibitors of axonal regeneration present in myelin--MAG, Nogo, and OMgp--all interact with the same receptor complex to effect inhibition via protein kinase C (PKC)-dependent activation of the small GTPase Rho. The transducing component of this receptor complex is the p75 neurotrophin receptor. Here we show that MAG binding to cerebellar neurons induces alpha- and then gamma-secretase proteolytic cleavage of p75, in a protein kinase C-dependent manner, and that this cleavage is necessary for both activation of Rho and inhibition of neurite outgrowth
— id: 66610, year: 2005, vol: 46, page: 849, stat: Journal Article,

{alpha}-Syntrophin regulates ARMS localization at the neuromuscular junction and enhances EphA4 signaling in an ARMS-dependent manner
Luo, Shuo; Chen, Yu; Lai, Kwok-On; Arevalo, Juan Carlos; Froehner, Stanley C; Adams, Marvin E; Chao, Moses V; Ip, Nancy Y
2005 Jun 6;169(5):813-824, Journal of cell biology
EphA4 signaling has recently been implicated in the regulation of synapse formation and plasticity. In this study, we show that ankyrin repeat-rich membrane spanning (ARMS; also known as a kinase D-interacting substrate of 220 kD), a substrate for ephrin and neurotrophin receptors, was expressed in developing muscle and was concentrated at the neuromuscular junction (NMJ). Using yeast two-hybrid screening, we identified a PDZ (PSD-95, Dlg, ZO-1) domain protein, alpha-syntrophin, as an ARMS-interacting protein in muscle. Overexpression of alpha-syntrophin induced ARMS clustering in a PDZ domain-dependent manner. Coexpression of ARMS enhanced EphA4 signaling, which was further augmented by the presence of alpha-syntrophin. Moreover, the ephrin-A1-induced tyrosine phosphorylation of EphA4 was reduced in C2C12 myotubes after the blockade of ARMS and alpha-syntrophin expression by RNA interference. Finally, alpha-syntrophin-null mice exhibited a disrupted localization of ARMS and EphA4 at the NMJ and a reduced expression of ARMS in muscle. Altogether, our findings suggest that ARMS may play an important role in regulating postsynaptic signal transduction through the syntrophin-mediated localization of receptor tyrosine kinases such as EphA4
— id: 66611, year: 2005, vol: 169, page: 813, stat: Journal Article,

Neuregulin-1 type III determines the ensheathment fate of axons
Taveggia, Carla; Zanazzi, George; Petrylak, Ashley; Yano, Hiroko; Rosenbluth, Jack; Einheber, Steven; Xu, Xiaorong; Esper, Raymond M; Loeb, Jeffrey A; Shrager, Peter; Chao, Moses V; Falls, Douglas L; Role, Lorna; Salzer, James L
2005 Sep 1;47(5):681-694, Neuron
The signals that determine whether axons are ensheathed or myelinated by Schwann cells have long been elusive. We now report that threshold levels of neuregulin-1 (NRG1) type III on axons determine their ensheathment fate. Ensheathed axons express low levels whereas myelinated fibers express high levels of NRG1 type III. Sensory neurons from NRG1 type III deficient mice are poorly ensheathed and fail to myelinate; lentiviral-mediated expression of NRG1 type III rescues these defects. Expression also converts the normally unmyelinated axons of sympathetic neurons to myelination. Nerve fibers of mice haploinsufficient for NRG1 type III are disproportionately unmyelinated, aberrantly ensheathed, and hypomyelinated, with reduced conduction velocities. Type III is the sole NRG1 isoform retained at the axon surface and activates PI 3-kinase, which is required for Schwann cell myelination. These results indicate that levels of NRG1 type III, independent of axon diameter, provide a key instructive signal that determines the ensheathment fate of axons
— id: 58738, year: 2005, vol: 47, page: 681, stat: Journal Article,

Biochemical characterization of intracellular membranes bearing Trk neurotrophin receptors
Yano, Hiroko; Chao, Moses V
2005 Jun-Jul;30(6-7):767-777, Neurochemical research
Neurotrophin receptor trafficking plays an important role in directing cellular communication in developing as well as mature neurons. However, little is known about the requirements for intracellular localization of the neurotrophin receptors in neurons. To isolate the subcellular membrane compartments containing the Trk neurotrophin receptor, we performed biochemical subcellular fractionation experiments using primary cortical neurons and rat PC12 pheochromocytoma cells. By differential centrifugation and density gradient centrifugation, we have isolated Trk-bearing compartments, suggesting distinct membranous localization of Trk receptors. A number of Trk-interacting proteins, such as GIPC and dynein light chain Tctex-1 were found in these fractions. Additionally, membranes enriched in phosphorylated activated forms of Trk receptors were found upon ligand treatment in primary neurons and PC12 cells. Interestingly, density gradient centrifugation experiments showed that Trk receptors from PC12 cells are present in heavy membrane fractions, while Trk from primary neurons are fractionated in lighter membrane fractions. These results suggest that the intracellular membrane localization of Trk can differ according to cell type. Taken together, these biochemical approaches allowed separation of distinct Trk-bearing membrane pools, which may be involved in different functions of neurotrophin receptor signaling and trafficking
— id: 62361, year: 2005, vol: 30, page: 767, stat: Journal Article,

Cleavage of p75 Neurotrophin Receptor by {alpha}-Secretase and {gamma}-Secretase Requires Specific Receptor Domains
Zampieri, Niccolo; Xu, Chong-Feng; Neubert, Thomas A; Chao, Moses V
2005 Apr 15;280(15):14563-14571, Journal of biological chemistry
The p75 neurotrophin receptor (p75(NTR)), a member of the tumor necrosis factor superfamily of receptors, undergoes multiple proteolytic cleavage events. These events are initiated by an alpha-secretase-mediated release of the extracellular domain followed by a gamma-secretase-mediated intramembrane cleavage. However, the specific determinants of p75(NTR) cleavage events are unknown. Many other substrates of gamma-secretase cleavage have been identified, including Notch, amyloid precursor protein, and ErbB4, indicating there is broad substrate recognition by gamma-secretase. Using a series of deletion mutations and chimeric receptors of p75(NTR) and the related Fas receptor, we have identified domains that are essential for p75(NTR) proteolysis. The initial alpha-secretase cleavage was extracellular to the transmembrane domain. Unfortunately, deletion mutants were not capable of defining the requirements of ectodomain shedding. Although this cleavage is promiscuous with respect to amino acid sequence, its position with respect to the transmembrane domain is invariant. The generation of chimeric receptors exchanging different domains of noncleavable Fas receptor with p75(NTR), however, revealed that a discrete domain above the membrane is sufficient for efficient cleavage of p75(NTR). Mass spectrometric analysis confirmed the cleavage can occur with a truncated p75(NTR) displaying only 15 extracellular amino acids in the stalk region
— id: 50628, year: 2005, vol: 280, page: 14563, stat: Journal Article,

Brain-specific deletion of neuropathy target esterase/swisscheese results in neurodegeneration
Akassoglou, Katerina; Malester, Brian; Xu, Jixiang; Tessarollo, Lino; Rosenbluth, Jack; Chao, Moses V
2004 May 6;101(14):5075-5080, Proceedings of the National Academy of Sciences of the United States of America
Neuropathy target esterase (NTE) is a neuronal membrane protein originally identified for its property to be modified by organo-phosphates (OPs), which in humans cause neuropathy characterized by axonal degeneration. Drosophila mutants for the homolog gene of NTE, swisscheese (sws), indicated a possible involvement of sws in the regulation of axon-glial cell interaction during glial wrapping. However, the role of NTE/sws in mammalian brain pathophysiology remains unknown. To investigate NTE function in vivo, we used the cre/loxP site-specific recombination strategy to generate mice with a specific deletion of NTE in neuronal tissues. Here we show that loss of NTE leads to prominent neuronal pathology in the hippocampus and thalamus and also defects in the cerebellum. Absence of NTE resulted in disruption of the endoplasmic reticulum, vacuolation of nerve cell bodies, and abnormal reticular aggregates. Thus, these results identify a physiological role for NTE in the nervous system and indicate that a loss-of-function mechanism may contribute to neurodegenerative diseases characterized by vacuolation and neuronal loss
— id: 46188, year: 2004, vol: 101, page: 5075, stat: Journal Article,

A unique pathway for sustained neurotrophin signaling through an ankyrin-rich membrane-spanning protein
Arevalo, Juan Carlos; Yano, Hiroko; Teng, Kenneth K; Chao, Moses V
2004 Jul 16;23(12):2358-2368, EMBO journal
A major question in cell biology is how molecular specificity is achieved by different growth factor receptors that activate apparently identical signaling events. For the neurotrophin family, a distinguishing feature is the ability to maintain a prolonged duration of signal transduction. However, the mechanisms by which neurotrophin receptors assemble such a sustained signaling complex are not understood. Here we report that an unusual ankyrin-rich transmembrane protein (ARMS+kidins220) is closely associated with Trk receptor tyrosine kinases, and not the EGF receptor. This association requires interactions between transmembrane domains of Trk and ARMS. ARMS is rapidly tyrosine phosphorylated after binding of neurotrophins to Trk receptors and provides a docking site for the CrkL-C3G complex, resulting in Rap1-dependent sustained ERK activation. Accordingly, disruption of Trk-ARMS or the ARMS-CrkL interaction with dominant-negative ARMS mutants, or treatment with small interference RNA against ARMS substantially reduce neurotrophin-elicited signaling to ERK, but without any effect upon Ras or Akt activation. These findings suggest that ARMS acts as a major and neuronal-specific platform for prolonged MAP kinase signaling by neurotrophins
— id: 46151, year: 2004, vol: 23, page: 2358, stat: Journal Article,

Ternary complex with Trk, p75, and an ankyrin-rich membrane spanning protein
Chang, Mi-Sook; Arevalo, Juan Carlos; Chao, Moses V
2004 Oct 15;78(2):186-192, Journal of neuroscience research
Neurotrophins play many critical roles in regulating neuronal plasticity, survival, and differentiation in the nervous system. Neurotrophins recognize two different receptors, the Trk receptor tyrosine kinase and the p75 neurotrophin receptor, which are associated closely. Several adaptor proteins are associated with each receptor. An ankyrin-rich membrane spanning protein (ARMS), originally identified as a substrate for protein kinase D (Kidins220) and as a p75 interacting protein, serves as a novel downstream target of Trk receptor tyrosine kinases. Kidins220/ARMS is co-expressed frequently with Trk and p75 and represents the only membrane-associated protein known to interact with both receptors. We report here that a ternary complex can be formed between Trk, p75, and Kidins220/ARMS. The extracellular domains of the TrkA and the p75 receptors are necessary for their association, whereas the juxtamembrane region of p75 was responsible for the interaction with Kidins220/ARMS. Interestingly, increasing the level of Kidins220/ARMS expression resulted in a decreased association of TrkA with p75. These findings thus suggest that Kidins220/ARMS plays an important role in regulating interactions between Trk and p75 neurotrophin receptors
— id: 46461, year: 2004, vol: 78, page: 186, stat: Journal Article,

Unique Features of Neurotrophin Receptor Signaling
Chao, Moses V.
[S.l.] : NIH, 2004,
The generation and differentiation of neurons and glial cells are dependent upon cell-cell interactions mediated by a wide variety of growth factors and cytokines. Dr. Chao's laboratory is interested in receptor-mediated mechanisms that direct cell differentiation versus cell proliferation in the nervous system. A major goal is to identify the biochemical steps that provide specificity in NGF signaling. Control of cell survival and death by neurotrophins is dictated by an unusual transduction system consisting of two transmembrane receptors, the TrkA tyrosine kinase and the p75 neurotrophin receptor, a member of the TNF receptor superfamily. The structural and biochemical features of these two receptors are being defined together with their intracellular signaling mechanisms
— id: 1426, year: 2004, vol: , page: , stat: ,

Neurotrophin survival signaling mechanisms
Chao, Moses V; Lee, Francis S
2004 Dec;6(6 Suppl):S7-11, Journal of Alzheimer's Disease
— id: 55906, year: 2004, vol: 6, page: S7, stat: Journal Article,

The p75NTR-interacting protein SC1 inhibits cell cycle progression by transcriptional repression of cyclin E
Chittka, Alexandra; Arevalo, Juan Carlos; Rodriguez-Guzman, Maria; Perez, Pilar; Chao, Moses V; Sendtner, Michael
2004 Mar 29;164(7):985-996, Journal of cell biology
Schwann cell factor 1 (SC1), a p75 neurotrophin receptor-interacting protein, is a member of the positive regulatory/suppressor of variegation, enhancer of zeste, trithorax (PR/SET) domain-containing zinc finger protein family, and it has been shown to be regulated by serum and neurotrophins. SC1 shows a differential cytoplasmic and nuclear distribution, and its presence in the nucleus correlates strongly with the absence of bromodeoxyuridine (BrdU) in these nuclei. Here, we investigated potential transcriptional activities of SC1 and analyzed the function of its various domains. We show that SC1 acts as a transcriptional repressor when it is tethered to Gal4 DNA-binding domain. The repressive activity requires a trichostatin A-sensitive histone deacetylase (HDAC) activity, and SC1 is found in a complex with HDACs 1, 2, and 3. Transcriptional repression exerted by SC1 requires the presence of its zinc finger domains and the PR domain. Additionally, these two domains are involved in the efficient block of BrdU incorporation by SC1. The zinc finger domains are also necessary to direct SC1's nuclear localization. Lastly, SC1 represses the promoter of a promitotic gene, cyclin E, suggesting a mechanism for how growth arrest is regulated by SC1
— id: 66612, year: 2004, vol: 164, page: 985, stat: Journal Article,

Prevention of apoptotic but not necrotic cell death following neuronal injury by neurotrophins signaling through the tyrosine kinase receptor
Kim, Dong H; Zhao, Xiurong; Tu, Christina H; Casaccia-Bonnefil, Patrizia; Chao, Moses V
2004 Jan;100(1):79-87, Journal of neurosurgery
OBJECT: Neurotrophins prevent the death of neurons during embryonal development and have potential as therapeutic agents. During development, neuronal death occurs only by apoptosis and not by necrosis. Following injury, however, neurons can die by both processes. Data from prior studies have not clearly indicated whether neurotrophins can decrease apoptosis compared with necrosis. The goal of this study was to determine the effect of neurotrophin treatment on each of these processes following injury and to characterize the receptor(s) required. METHODS: The authors used an in vitro model of injury with the aid of primary cortical neurons obtained from rat embryos. After 9 days in culture and the elimination of glia, homogeneous and mature neurons were available for experimentation. Noxious stimuli were applied, including radiation, hypoxia, and ischemia. Subsequent cell death by apoptosis or necrosis was noted based on morphological and enzymatic assessments (such as lactate dehydrogenase [LDH] release) and assays for DNA fragmentation. The effect of treatment with nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 was determined. Finally, Western blot analyses were performed to note the neurotrophin receptor status in the neurons (tyrosine kinase receptors [Trks] and p75). The authors studied different stimuli-induced cell death by using different processes. With the application of radiation, cells died primarily by apoptosis, as evidenced by cell shrinkage, the presence of apoptotic bodies, and specific DNA fragmentation. This was a delayed process (> 6 hours) that could be reduced by gene transcription or protein synthesis inhibitors. With ischemia, cells died immediately by necrosis, showing cell enlargement and rupture. Ischemic cell death was not affected by the inhibition of macromolecular synthesis. Hypoxia produced a mixture of the two cell death processes. Both BDNF and neurotrophin-3 demonstrated protection against apoptotic cell death only. Statistically significant decreases of both LDH release and apoptosis-specific DNA fragmentation were noted following radiation and hypoxia, but not for ischemia. Nerve growth factor, unlike the other neurotrophins, did not affect apoptosis because a functional receptor, Trk A, was not expressed by the cortical neurons. There was expression of both Trk B and Trk C, which bind BDNF and neurotrophin-3. CONCLUSIONS: These findings have significant clinical implications. Neurotrophins may only be effective in disorders in which apoptosis, and not necrosis, is the major process. Furthermore, the Trk signaling cascade must be activated for this response to occur. Because the expression of these receptors diminishes in adulthood, neurotrophin application may be most appropriate in the pediatric population
— id: 66613, year: 2004, vol: 100, page: 79, stat: Journal Article,

A novel p75 neurotrophin receptor-related protein, NRH2, regulates nerve growth factor binding to the TrkA receptor
Murray, Simon S; Perez, Pilar; Lee, Ramee; Hempstead, Barbara L; Chao, Moses V
2004 Apr 17;24(11):2742-2749, Journal of neuroscience
Nerve growth factor (NGF) functions as a ligand for two receptors, the TrkA tyrosine kinase receptor and the p75 neurotrophin receptor (p75NTR). The Ig-like domains of Trk receptors and the cysteine-rich repeats of p75NTR are involved in binding to the neurotrophins. Recently, a closely related gene to p75NTR called neurotrophin receptor homolog-2 (NRH2) was identified; however, the function of NRH2 and its relevance to neurotrophin signaling are unclear. NRH2 contains a similar transmembrane and intracellular domain as p75NTR but lacks the characteristic cysteine-rich repeats in the extracellular domain. Here we show that NRH2 is expressed in several neuronal populations that also express p75NTR and Trk receptors. NRH2 does not bind to NGF; however, coimmunoprecipitation experiments demonstrate that NRH2 is capable of interacting with TrkA receptors. Coexpression of NRH2 with TrkA receptors resulted in the formation of high-affinity binding sites for NGF. These results indicate that a transmembrane protein related to p75NTR is capable of modulating Trk receptor binding properties
— id: 46201, year: 2004, vol: 24, page: 2742, stat: Journal Article,

Fibrin depletion reverses relapsing paralysis in central nervous system autoimmune disease
Nuriel, T; Chao, MV; Akassoglou, K
2004 FEB ;10(1):258-261, Multiple sclerosis
— id: 46853, year: 2004, vol: 10, page: 258, stat: Journal Article,

Transactivation of Trk neurotrophin receptors by G-protein-coupled receptor ligands occurs on intracellular membranes
Rajagopal, Rithwick; Chen, Zhe-Yu; Lee, Francis S; Chao, Moses V
2004 Jul 28;24(30):6650-6658, Journal of neuroscience
Neurotrophins, such as NGF and BDNF, activate Trk receptor tyrosine kinases through receptor dimerization at the cell surface followed by autophosphorylation and intracellular signaling. It has been shown that activation of Trk receptor tyrosine kinases can also occur via a G-protein-coupled receptor (GPCR) mechanism, without involvement of neurotrophins. Two GPCR ligands, adenosine and pituitary adenylate cyclase-activating polypeptide (PACAP), can activate Trk receptor activity to increase the survival of neural cells through stimulation of Akt activity. To investigate the mechanism of Trk receptor transactivation, we have examined the localization of Trk receptors in PC12 cells and primary neurons after treatment with adenosine agonists and PACAP. In contrast to neurotrophin treatment, Trk receptors were sensitive to transcriptional and translational inhibitors, and they were found predominantly in intracellular locations particularly associated with Golgi membranes. Biotinylation and immunostaining experiments confirm that most of the transactivated Trk receptors are found in intracellular membranes. These results indicate that there are alternative modes of activating Trk receptor tyrosine kinases in the absence of neurotrophin binding at the cell surface and that receptor signaling may occur and persist inside of neuronal cells
— id: 48230, year: 2004, vol: 24, page: 6650, stat: Journal Article,

Motors, adaptors, and receptors: key elements of neuronal transport
Schiavo, Giampietro; Chao, Moses V
2004 Feb 5;58(2):161-163, Journal of neurobiology
— id: 66614, year: 2004, vol: 58, page: 161, stat: Journal Article,

Mechanisms of neurotrophin receptor vesicular transport
Yano, Hiroko; Chao, Moses V
2004 Feb 5;58(2):244-257, Journal of neurobiology
Accumulating evidence has indicated that neurotrophin receptor trafficking plays an important role in neurotrophin-mediated signaling in developing as well as mature neurons. However, little is known about the molecular mechanisms and the components of neurotrophin receptor vesicular transport. This article will describe how neurotrophin receptors, Trk and p75 neurotrophin receptor (p75NTR), are intimately involved in the axonal transport process. In particular, the molecules that may direct Trk receptor trafficking in the axon will be discussed. Finally, potential mechanisms by which receptor-containing vesicles link to molecular cytoskeletal motors will be presented
— id: 42625, year: 2004, vol: 58, page: 244, stat: Journal Article,

A critical role for the stalk domain of p75 neurotrophin receptor during alpha-secretase cleavage
Zampieri, N; Chao, MV
2004 NOV ;15(3):127A-127A, Molecular biology of the cell
— id: 50420, year: 2004, vol: 15, page: 127A, stat: Journal Article,

Structural biology. The p75 NGF receptor exposed
Zampieri, Niccolo; Chao, Moses V
2004 Jun 7;304(5672):833-834, Science
— id: 46202, year: 2004, vol: 304, page: 833, stat: Journal Article,

Fibrin functions and signaling in nervous system regeneration
Akassoglou, K; Nuriel, T; Pearson, Z; Zampieri, N; Chao, MV
2003 SEP ;4(4):8-8, Glia
— id: 55505, year: 2003, vol: 4, page: 8, stat: Journal Article,

Telomerase activity in the subventricular zone of adult mice
Caporaso, Gregg L; Lim, Daniel A; Alvarez-Buylla, Arturo; Chao, Moses V
2003 Aug;23(4):693-702, Molecular & cellular neurosciences
The subventricular zone (SVZ) is the most active site for the production of new neurons in the adult mouse brain. Neural stem cells in the adult SVZ give rise to neuroblasts that travel via the rostral migratory stream (RMS) to the olfactory bulb, where they differentiate into interneurons. The enzyme telomerase has been identified in other population of stem cells and is necessary for the synthesis of telomeric DNA to prevent chromosomal shortening, end-to-end fusions, and apoptosis during successive rounds of cell division. However, previous studies have failed to detect telomerase in the adult mammalian brain. Here we demonstrate that telomerase is expressed by all brain regions shortly after birth, but becomes restricted to the SVZ and olfactory bulb in the adult mouse brain. Cultures of neural precursor cells or of migratory neuroblasts purified from the SVZ were each found to possess telomerase activity. After elimination of migrating neuroblasts and immature precursor cells in vivo by treatment with cytosine-beta-D-arabinofuranoside (Ara-C), telomerase activity was still detectable in the remaining SVZ, which includes a population of neural stem cells. Following withdrawal of Ara-C, telomerase activity subsequently increased with a time course that parallels regeneration of the SVZ network and RMS. Finally, intracranial surgery alone, which has previously been shown to increase the number of cells in the SVZ, produced higher telomerase levels in the SVZ. We conclude that telomerase is active in neural precursor cells of the adult mouse and suggest that its regulation is an important parameter for cellular proliferation to occur in the mammalian brain
— id: 38379, year: 2003, vol: 23, page: 693, stat: Journal Article,

Dependence receptors: what is the mechanism?
Chao, Moses V
2003 Sep 16;2003(200):PE38-PE38, Science's STKE
Receptors of diverse primary structure and with diverse ligands have been reported to be capable of stimulating apoptosis in the absence of ligand binding. These receptors are called dependence receptors, and the newest member of this family appears to be the Sonic hedgehog receptor Patched, which has been reported to stimulate apoptosis when expressed in the absence of its ligand. The signaling mechanisms that account for this type of receptor activity are unknown. Several theories behind how dependence receptors may trigger cell death are described
— id: 38378, year: 2003, vol: 2003, page: PE38, stat: Journal Article,

Neurotrophins and their receptors: a convergence point for many signalling pathways
Chao, Moses V
2003 Apr;4(4):299-309, Nature reviews. Neuroscience
— id: 38383, year: 2003, vol: 4, page: 299, stat: Journal Article,

Retrograde transport redux
Chao, Moses V
2003 Jul 3;39(1):1-2, Neuron
Trafficking of trophic factors in axons can occur in a retrograde and anterograde direction. Recent findings bring further support for a vesicle-based process for retrograde transport but raise new questions that need to be pursued. Unraveling the exact mechanisms that account for retrograde transport of neurotrophins and their receptors will reveal the cellular requirements for propagating trophic signals over long distances
— id: 38381, year: 2003, vol: 39, page: 1, stat: Journal Article,

Regulated Intramembrane Proteolysis of the p75 Neurotrophin Receptor Modulates Its Association with the TrkA Receptor
Jung, Kwang-Mook; Tan, Serena; Landman, Natalie; Petrova, Kseniya; Murray, Simon; Lewis, Renee; Kim, Peter K; Kim, Dae Sup; Ryu, Sung Ho; Chao, Moses V; Kim, Tae-Wan
2003 Oct 24;278(43):42161-42169, Journal of biological chemistry
The generation of biologically active proteins by regulated intramembrane proteolysis is a highly conserved mechanism in cell signaling. Presenilin-dependent gamma-secretase activity is responsible for the intramembrane proteolysis of selected type I membrane proteins, including beta-amyloid precursor protein (APP) and Notch. A small fraction of intracellular domains derived from both APP and Notch translocates to and appears to function in the nucleus, suggesting a generic role for gamma-secretase cleavage in nuclear signaling. Here we show that the p75 neurotrophin receptor (p75NTR) undergoes presenilin-dependent intramembrane proteolysis to yield the soluble p75-intracellular domain. The p75NTR is a multifunctional type I membrane protein that promotes neurotrophin-induced neuronal survival and differentiation by forming a heteromeric co-receptor complex with the Trk receptors. Mass spectrometric analysis revealed that gamma-secretase-mediated cleavage of p75NTR occurs at a position located in the middle of the transmembrane (TM) domain, which is reminiscent of the amyloid beta-peptide 40 (Abeta40) cleavage of APP and is topologically distinct from the major TM cleavage site of Notch 1. Size exclusion chromatography and co-immunoprecipitation analyses revealed that TrkA forms a molecular complex together with either full-length p75 or membrane-tethered C-terminal fragments. The p75-ICD was not recruited into the TrkA-containing high molecular weight complex, indicating that gamma-secretase-mediated removal of the p75 TM domain may perturb the interaction with TrkA. Independent of the possible nuclear function, our studies suggest that gamma-secretase-mediated p75NTR proteolysis plays a role in the formation/disassembly of the p75-TrkA receptor complex by regulating the availability of the p75 TM domain that is required for this interaction
— id: 38380, year: 2003, vol: 278, page: 42161, stat: Journal Article,

JNK-interacting protein 1 promotes Akt1 activation
Kim, Albert H; Sasaki, Takehiko; Chao, Moses V
2003 Aug 8;278(32):29830-29836, Journal of biological chemistry
Members of the JNK pathway are organized together by virtue of interactions with JNK interacting protein 1 (JIP1), a scaffold protein. Here we have investigated the possibility that JIP1 may also affect the catalytic activity of Akt1, a serine/threonine kinase that has been implicated in multiple cellular processes, including survival and proliferation. JIP1 expression enhanced Akt1 kinase activity in a dose-dependent manner following serum starvation in 293 cells. Cellular activation of Akt1 following stimulation with low concentrations of insulin-like growth factor (IGF-1) was elevated in the presence of JIP1. JIP1 expression also prolonged Akt1 stimulation after a short IGF-1 pulse. The mechanism of JIP1-mediated Akt1 activation involved JIP1 protein binding to the Akt1 pleckstrin homology domain, which in turn promoted the phosphorylation of the activation T-loop of Akt1 by phosphoinositide-dependent kinase-1. These results suggest that, in certain cellular contexts, JIP1 may act as an Akt1 scaffold, which regulates the enzymatic activity of Akt1. This study also indicates that JIP1 expression can exert signaling effects independent of JNK activity
— id: 38382, year: 2003, vol: 278, page: 29830, stat: Journal Article,

Neurotrophin-induced melanoma cell migration is mediated through the actin-bundling protein fascin
Shonukan, Oluwatoyin; Bagayogo, Issa; McCrea, Pierre; Chao, Moses; Hempstead, Barbara
2003 Jun 5;22(23):3616-3623, Oncogene
Expression of the p75 neurotrophin receptor (p75(NTR)) in primary melanomas is associated with deeply invasive lesions. In turn, there is expression of high levels of neurotrophins at the invasion front of normal tissue adjacent to brain metastases, thus implicating this growth factor-receptor system in melanoma tumorigenesis. The neurotrophins nerve growth factor (NGF) and neurotrophin-3 (NT-3) are potent chemotactic agents for human melanoma cells which express p75(NTR)in vitro. Here we show that the actin-bundling protein fascin specifically interacts with p75(NTR) in an NGF-dependent manner by co-immunoprecipitation and colocalization in melanoma cells that express the two proteins endogenously. In addition, expression of a fascin point mutant at the serine phosphorylation site (serine 39) regulating actin binding abrogates neurotrophin-induced migration. These results suggest a causal role for NGF-mediated dephosphorylation of serine 39 on fascin in mediating actin binding and subsequent melanoma cell migration
— id: 66615, year: 2003, vol: 22, page: 3616, stat: Journal Article,

p75(NTR) binds fibrin and regulates extracellular proteolysis and integrin functions
Akassoglou, K; Chao, MV
2002 NOV ;13(4):488A-489A, Molecular biology of the cell
— id: 37193, year: 2002, vol: 13, page: 488A, stat: Journal Article,

ARMS, a novel downstream target of neurotrophin and ephrin receptors, interacts with CDCrel-1
Chang, M; Arevalo, J; Kong, H; Chao, MV
2002 NOV ;13(4):538A-538A, Molecular biology of the cell
— id: 37194, year: 2002, vol: 13, page: 538A, stat: Journal Article,

Neurotrophins: to cleave or not to cleave
Chao, Moses V; Bothwell, Mark
2002 Jan 3;33(1):9-12, Neuron
The family of neurotrophic factors known as neurotrophins has yielded a series of surprises, both with regard to the broad extent of their functional roles and the remarkable complexity of their signaling mechanisms. The recent discovery that a neurotrophin precursor protein and its proteolytically processed products may differentially activate pro- and antiapoptotic cellular responses, through preferential activation of Trk or p75 receptors, promises to unveil yet another level of regulatory complexity
— id: 38388, year: 2002, vol: 33, page: 9, stat: Journal Article,

Interacting proteins of neurotrophin receptors
Chao, MV; Yano, H
2002 Jun;81(7):79-79, Journal of neurochemistry
— id: 32369, year: 2002, vol: 81, page: 79, stat: Journal Article,

Lack of the cell-cycle inhibitor p27Kip1 results in selective increase of transit-amplifying cells for adult neurogenesis
Doetsch, Fiona; Verdugo, Jose Manuel-Garcia; Caille, Isabelle; Alvarez-Buylla, Arturo; Chao, Moses V; Casaccia-Bonnefil, Patrizia
2002 Mar 15;22(6):2255-2264, Journal of neuroscience
The subventricular zone (SVZ) is the largest germinal layer in the adult mammalian brain and comprises stem cells, transit-amplifying progenitors, and committed neuroblasts. Although the SVZ contains the highest concentration of dividing cells in the adult brain, the intracellular mechanisms controlling their proliferation have not been elucidated. We show here that loss of the cyclin-dependent kinase inhibitor p27Kip1 has very specific effects on a population of CNS progenitors responsible for adult neurogenesis. Using bromodeoxyuridine and [(3)H]thymidine incorporation to label cells in S phase and cell-specific markers and electron microscopy to identify distinct cell types, we compared the SVZ structure and proliferation characteristics of wild-type and p27Kip1-null mice. Loss of p27Kip1 had no effect on the number of stem cells but selectively increased the number of the transit-amplifying progenitors concomitantly with a reduction in the number of neuroblasts. We conclude that cell-cycle regulation of SVZ adult progenitors is remarkably cell-type specific, with p27Kip1 being a key regulator of the cell division of the transit-amplifying progenitors
— id: 38386, year: 2002, vol: 22, page: 2255, stat: Journal Article,

Receptor protein tyrosine phosphatase (RPTP)-beta is involved in functional recovery from demyelinating lesions of the spinal cord
Harroch, S; Casaccia-Bonnefil, P; Furtado, G; Rosenbluth, J; Chao, M; Lafaille, J; Buxbaum, J; Schlessinger, J
2002 May;(Suppl 1):S84-S84 #P328, Glia
— id: 28182, year: 2002, vol: , page: S84, stat: Journal Article,

A critical role for the protein tyrosine phosphatase receptor type Z in functional recovery from demyelinating lesions
Harroch, Sheila; Furtado, Glaucia C; Brueck, Wolfgang; Rosenbluth, Jack; Lafaille, Juan; Chao, Moses; Buxbaum, Joseph D; Schlessinger, Joseph
2002 Nov;32(3):411-414, Nature genetics
Several lines of evidence suggest that tyrosine phosphorylation is a key element in myelin formation, differentiation of oligodendrocytes and Schwann cells, and recovery from demyelinating lesions. Multiple sclerosis is a demyelinating disease of the human central nervous system, and studies of experimental demyelination indicate that remyelination in vivo requires the local generation, migration or maturation of new oligodendrocytes, or some combination of these. Failure of remyelination in multiple sclerosis could result from the failure of any of these processes or from the death of oligodendrocytes. Ptprz encodes protein tyrosine phosphatase receptor type Z (Ptpz, also designated Rptpbeta), which is expressed primarily in the nervous system but also in oligodendrocytes, astrocytes and neurons. Here we examine the susceptibility of mice deficient in Ptprz to experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. We observe that mice deficient in Ptprz show impaired recovery from EAE induced by myelin oligodendrocyte glycoprotein (MOG) peptide. This sustained paralysis is associated with increased apoptosis of mature oligodendrocytes in the spinal cords of mutant mice at the peak of inflammation. We further demonstrate that expression of PTPRZ1, the human homolog of Ptprz, is induced in multiple sclerosis lesions and that the gene is specifically expressed in remyelinating oligodendrocytes in these lesions. These results support a role for Ptprz in oligodendrocyte survival and in recovery from demyelinating disease
— id: 66616, year: 2002, vol: 32, page: 411, stat: Journal Article,

Akt1 regulates a JNK scaffold during excitotoxic apoptosis
Kim, Albert H; Yano, Hiroko; Cho, Han; Meyer, Debra; Monks, Bob; Margolis, Ben; Birnbaum, Morris J; Chao, Moses V
2002 Aug 15;35(4):697-709, Neuron
Cell survival is determined by a balance among signaling cascades, including those that recruit the Akt and JNK pathways. Here we describe a novel interaction between Akt1 and JNK interacting protein 1 (JIP1), a JNK pathway scaffold. Direct association between Akt1 and JIP1 was observed in primary neurons. Neuronal exposure to an excitotoxic stimulus decreased the Akt1-JIP1 interaction and concomitantly increased association between JIP1 and JNK. Akt1 interaction with JIP1 inhibited JIP1-mediated potentiation of JNK activity by decreasing JIP1 binding to specific JNK pathway kinases. Consistent with this view, neurons from Akt1-deficient mice exhibited higher susceptibility to kainate than wild-type littermates. Overexpression of Akt1 mutants that bind JIP1 reduced excitotoxic apoptosis. These results suggest that Akt1 binding to JIP1 acts as a regulatory gate preventing JNK activation, which is released under conditions of excitotoxic injury
— id: 38384, year: 2002, vol: 35, page: 697, stat: Journal Article,

Distinctive features of Trk neurotrophin receptor transactivation by G protein-coupled receptors
Lee, Francis S; Rajagopal, Rithwick; Chao, Moses V
2002 Feb;13(1):11-17, Cytokine & growth factor reviews
Ligands for G protein-coupled receptors (GPCR) are capable of activating mitogenic receptor tyrosine kinases, in addition to the mitogen-activated protein (MAP) kinase signaling pathway and classic G protein-dependent signaling pathways involving adenylyl cyclase and phospholipase. For example, receptors for epidermal growth factor (EGF), insulin-like growth-1 and platelet-derived growth factor and can be transactivated through G protein-coupled receptors. Neurotrophins, such as NGF, BDNF and NT-3 also utilize receptor tyrosine kinases, namely TrkA, TrkB and TrkC. Recently, it has been shown that activation of Trk receptor tyrosine kinases can also occur via a G protein-coupled receptor mechanism, without involvement of neurotrophins. Adenosine and adenosine agonists can activate Trk receptor phosphorylation specifically through the seven transmembrane spanning adenosine 2A (A2A) receptor. Several features of Trk receptor transactivation are noteworthy and differ significantly from other transactivation events. Trk receptor transactivation is slower and results in a selective increase in activated Akt. Unlike the biological actions of other tyrosine kinase receptors, increased Trk receptor activity by adenosine resulted in increased cell survival. This article will discuss potential mechanisms by which adenosine can activate trophic responses through Trk tyrosine kinase receptors
— id: 38389, year: 2002, vol: 13, page: 11, stat: Journal Article,

Activation of Trk neurotrophin receptor signaling by pituitary adenylate cyclase-activating polypeptides
Lee, Francis S; Rajagopal, Rithwick; Kim, Albert H; Chang, Paul C; Chao, Moses V
2002 Mar 15;277(11):9096-9102, Journal of biological chemistry
Pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide that acts through G protein-coupled receptors, exerts neuroprotective effects upon many neuronal populations. However, the intracellular signaling mechanisms that account for PACAP's trophic effects are not well characterized. Here we have tested the possibility that PACAP uses neurotrophin signaling pathways. We have found that PACAP treatment resulted in an increase in TrkA tyrosine kinase activity in PC12 cells and TrkB activity in hippocampal neurons. The activation of TrkA receptors by PACAP required at least 1 h of treatment and did not involve binding to nerve growth factor. Moreover, PACAP induced an increase in activated Akt through a Trk-dependent mechanism that resulted in increased cell survival after trophic factor withdrawal. The increases in Trk and Akt were blocked by K252a, an inhibitor of Trk receptor activity. In addition, transactivation of TrkA receptors by PACAP could be inhibited with PP1, an inhibitor of Src family kinases or BAPTA/AM, (1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid acetoxymethyl ester), an intracellular calcium chelator. Therefore, PACAP can exert trophic effects through a mechanism involving Trk receptors and utilization of tyrosine kinase signaling. This ability may explain several neuroprotective actions of PACAP upon neuronal populations after injury, nerve lesion, or neurotrophin deprivation
— id: 38387, year: 2002, vol: 277, page: 9096, stat: Journal Article,

Annexin II light chain regulates sensory neuron-specific sodium channel expression
Okuse, Kenji; Malik-Hall, Misbah; Baker, Mark D; Poon, W-Y Louisa; Kong, Haeyoung; Chao, Moses V; Wood, John N
2002 Jun 6;417(6889):653-656, Nature
The tetrodotoxin-resistant sodium channel Na(V)1.8/SNS is expressed exclusively in sensory neurons and appears to have an important role in pain pathways. Unlike other sodium channels, Na(V)1.8 is poorly expressed in cell lines even in the presence of accessory beta-subunits. Here we identify annexin II light chain (p11) as a regulatory factor that facilitates the expression of Na(V)1.8. p11 binds directly to the amino terminus of Na(V)1.8 and promotes the translocation of Na(V)1.8 to the plasma membrane, producing functional channels. The endogenous Na(V)1.8 current in sensory neurons is inhibited by antisense downregulation of p11 expression. Because direct association with p11 is required for functional expression of Na(V)1.8, disrupting this interaction may be a useful new approach to downregulating Na(V)1.8 and effecting analgesia
— id: 38385, year: 2002, vol: 417, page: 653, stat: Journal Article,

Association of Trk neurotrophin receptors with a PDZ-domain protein, GIPC
Yano, H; Milner, TA; Chao, MV
2002 NOV ;13(32):3029-3029, Molecular biology of the cell
— id: 105085, year: 2002, vol: 13, page: 3029, stat: Journal Article,

A novel mutation within the extracellular domain of TrkA causes constitutive receptor activation
Arevalo JC; Conde B; Hempstead BI; Chao MV; Martin-Zanca D; Perez P
2001 Mar 8;20(10):1229-1234, Oncogene
The TrkA NGF receptor extracellular region contains three leucine repeats flanked by cysteine clusters and two immunoglobulin-like domains that are required for specific ligand binding. Deletion of the immunoglobulin-like domains abolishes NGF binding and causes ligand independent activation of the receptor. Here we report a specific mutation that increases the binding affinity of the TrkA receptor for NGF. A change of proline 203 to alanine (P203A) in the linker region between the leucine repeats and the first Ig-like domain increased NGF binding by decreasing the ligand rate of dissociation. This mutated receptor was appropriately expressed on the cell surface and promoted ligand-independent neurite outgrowth in PC12nnr5 cells. The mutant receptor was capable of spontaneous dimerization and was constitutively phosphorylated in the absence of ligand. Moreover, expression of TrkA-P203A receptor in fibroblasts induced DNA synthesis and transformation and generated tumours in nude mice. These data suggest that domains outside of the immunoglobulin-like structure contribute to ligand binding and constitutive activation of Trk receptors
— id: 38396, year: 2001, vol: 20, page: 1229, stat: Journal Article,

Telomerase and oligodendrocyte differentiation
Caporaso GL; Chao MV
2001 Nov 15;49(3):224-234, Journal of neurobiology
Myelin in the mammalian central nervous system (CNS) is produced by oligodendrocytes, most of which arise from oligodendrocyte precursor cells (OPCs) during late embryonic and early postnatal development. Both external and internal cues have been implicated in regulating OPC exit from the cell cycle and differentiation into oligodendrocytes. In this study, we demonstrate that differentiation of cultured OPCs into mature oligodendrocytes is associated with lower levels of activity of telomerase, the ribonucleoprotein that synthesizes telomeric DNA at the ends of chromosomes. Differentiation is also associated with lower levels of mRNA encoding the catalytic subunit of telomerase (TERT), whereas no difference is seen in the expression of its telomeric template RNA component (TR). These data suggest a possible role for telomerase during normal growth and differentiation of oligodendrocytes that may be relevant to the mechanism of myelination in the CNS
— id: 26518, year: 2001, vol: 49, page: 224, stat: Journal Article,

Bradykinin and nerve growth factor release the capsaicin receptor from PtdIns(4,5)P2-mediated inhibition
Chuang HH; Prescott ED; Kong H; Shields S; Jordt SE; Basbaum AI; Chao MV; Julius D
2001 Jun 21;411(6840):957-962, Nature
Tissue injury generates endogenous factors that heighten our sense of pain by increasing the response of sensory nerve endings to noxious stimuli. Bradykinin and nerve growth factor (NGF) are two such pro-algesic agents that activate G-protein-coupled (BK2) and tyrosine kinase (TrkA) receptors, respectively, to stimulate phospholipase C (PLC) signalling pathways in primary afferent neurons. How these actions produce sensitization to physical or chemical stimuli has not been elucidated at the molecular level. Here, we show that bradykinin- or NGF-mediated potentiation of thermal sensitivity in vivo requires expression of VR1, a heat-activated ion channel on sensory neurons. Diminution of plasma membrane phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) levels through antibody sequestration or PLC-mediated hydrolysis mimics the potentiating effects of bradykinin or NGF at the cellular level. Moreover, recruitment of PLC-gamma to TrkA is essential for NGF-mediated potentiation of channel activity, and biochemical studies suggest that VR1 associates with this complex. These studies delineate a biochemical mechanism through which bradykinin and NGF produce hypersensitivity and might explain how the activation of PLC signalling systems regulates other members of the TRP channel family
— id: 38394, year: 2001, vol: 411, page: 957, stat: Journal Article,

The cytoplasmic and transmembrane domains of the p75 and Trk A receptors regulate high affinity binding to nerve growth factor
Esposito D; Patel P; Stephens RM; Perez P; Chao MV; Kaplan DR; Hempstead BL
2001 Aug 31;276(35):32687-32695, Journal of biological chemistry
Ligand-induced receptor oligomerization is an established mechanism for receptor-tyrosine kinase activation. However, numerous receptor-tyrosine kinases are expressed in multicomponent complexes with other receptors that may signal independently or alter the binding characteristics of the receptor-tyrosine kinase. Nerve growth factor (NGF) interacts with two structurally unrelated receptors, the Trk A receptor-tyrosine kinase and p75, a tumor necrosis factor receptor family member. Each receptor binds independently to NGF with predominantly low affinity (K(d) = 10(-9) m), but they produce high affinity binding sites (K(d) = 10(-11) m) upon receptor co-expression. Here we provide evidence that the number of high affinity sites is regulated by the ratio of the two receptors and by specific domains of Trk A and p75. Co-expression of Trk A containing mutant transmembrane or cytoplasmic domains with p75 yielded reduced numbers of high affinity binding sites. Similarly, co-expression of mutant p75 containing altered transmembrane and cytoplasmic domains with Trk A also resulted in predominantly low affinity binding sites. Surprisingly, extracellular domain mutations of p75 that abolished NGF binding still generated high affinity binding with Trk A. These results indicate that the transmembrane and cytoplasmic domains of Trk A and p75 are responsible for high affinity site formation and suggest that p75 alters the conformation of Trk A to generate high affinity NGF binding
— id: 38392, year: 2001, vol: 276, page: 32687, stat: Journal Article,

A prosurvival function for the p75 receptor death domain mediated via the caspase recruitment domain receptor-interacting protein 2
Khursigara G; Bertin J; Yano H; Moffett H; DiStefano PS; Chao MV
2001 Aug 15;21(16):5854-5863, Journal of neuroscience
In addition to promoting cell survival, neurotrophins also can elicit apoptosis in restricted cell types. Recent results indicate that nerve growth factor (NGF) can induce Schwann cell death via engagement of the p75 neurotrophin receptor. Here we describe a novel interaction between the p75 receptor and receptor-interacting protein 2, RIP2 (RICK/CARDIAK), that accounts for the ability of neurotrophins to choose between a survival-versus-death pathway. RIP2, an adaptor protein with a serine threonine kinase and a caspase recruitment domain (CARD), is highly expressed in dissociated Schwann cells and displays an endogenous association with p75. RIP2 binds to the death domain of p75 via its CARD domain in an NGF-dependent manner. The introduction of RIP2 into Schwann cells deficient in RIP2 conferred NGF-dependent nuclear transcription factor-kappaB (NF-kappaB) activity and decreased the cell death induced by NGF. Conversely, the expression of a dominant-negative version of RIP2 protein resulted in a loss of NGF-induced NF-kappaB induction and increased NGF-mediated cell death. These results indicate that adaptor proteins like RIP2 can provide a bifunctional switch for cell survival or cell death decisions mediated by the p75 neurotrophin receptor
— id: 38391, year: 2001, vol: 21, page: 5854, stat: Journal Article,

Akt Phosphorylates and Negatively Regulates Apoptosis Signal-Regulating Kinase 1
Kim AH; Khursigara G; Sun X; Franke TF; Chao MV
2001 Feb 1;21(3):893-901, Molecular & cellular biology
The Akt family of serine/threonine-directed kinases promotes cellular survival in part by phosphorylating and inhibiting death-inducing proteins. Here we describe a novel functional interaction between Akt and apoptosis signal-regulating kinase 1 (ASK1), a mitogen-activated protein kinase kinase kinase. Akt decreased ASK1 kinase activity stimulated by both oxidative stress and overexpression in 293 cells by phosphorylating a consensus Akt site at serine 83 of ASK1. Activation of the phosphoinositide 3-kinase (PI3-K)/Akt pathway also inhibited the serum deprivation-induced activity of endogenous ASK1 in L929 cells. An association between Akt and ASK1 was detected in cells by coimmunoprecipitation. Phosphorylation by Akt inhibited ASK1-mediated c-Jun N-terminal kinase and activating transcription factor 2 activities in intact cells. Finally, activation of the PI3-K/Akt pathway reduced apoptosis induced by ASK1 in a manner dependent on phosphorylation of serine 83 of ASK1. These results provide the first direct link between Akt and the family of stress-activated kinases
— id: 14637, year: 2001, vol: 21, page: 893, stat: Journal Article,

An Evolutionarily Conserved Transmembrane Protein That Is a Novel Downstream Target of Neurotrophin and Ephrin Receptors
Kong H; Boulter J; Weber JL; Lai C; Chao MV
2001 Jan 1;21(1):176-185, Journal of neuroscience
Appropriate development of nervous system connectivity involves a variety of processes, including neuronal life-and-death decisions, differentiation, axon guidance and migration, and synaptogenesis. Although these activities likely require specialized signaling events, few substrates unique to these neurotrophic functions have been identified. Here we describe the cloning of ankyrin repeat-rich membrane spanning (ARMS), which encodes a novel downstream target of neurotrophin and ephrin receptor tyrosine kinases, Trk and Eph, respectively. The amino acid sequence of ARMS is highly conserved from nematode to human, suggesting an evolutionarily conserved role for this protein. The ARMS protein consists of 1715 amino acids containing four putative transmembrane domains, multiple ankyrin repeats, a sterile alpha motif domain, and a potential PDZ-binding motif. In the rat, ARMS is specifically expressed in the developing nervous system and in highly plastic areas of the adult brain, regions enriched in Trks and Eph receptors. ARMS can physically associate with TrkA and p75 neurotrophin receptors. Moreover, endogenous ARMS protein is tyrosine phosphorylated after neurotrophin treatment of pheochromocytoma 12 cells and primary hippocampal neurons or ephrin B treatment of NG108-15 cells, demonstrating that ARMS is a downstream target for both neurotrophin and ephrin receptors
— id: 14638, year: 2001, vol: 21, page: 176, stat: Journal Article,

Kainate receptors expressed by a subpopulation of developing nociceptors rapidly switch from high to low Ca2+ permeability
Lee CJ; Kong H; Manzini MC; Albuquerque C; Chao MV; MacDermott AB
2001 Jul 1;21(13):4572-4581, Journal of neuroscience
Dorsal root ganglion (DRG) neurons first express kainate receptor subunits, predominantly GluR5, during embryonic development. In the DRG and throughout the nervous system, substantial editing of GluR5 mRNA occurs with developmental maturation (Bernard et al., 1999). The accompanying change in Ca(2+) permeability of functional kainate receptors that is the predicted outcome of this developmental regulation of mRNA editing has not been investigated. Here we report that kainate receptors on DRG neurons from late embryonic and newborn rats are predominantly Ca(2+) permeable but then become fully Ca(2+) impermeable later in the first postnatal week. Using multiple markers for nociceptor subpopulations, we show that this switch in Ca(2+) permeability is not caused by the appearance of a new subpopulation of nociceptors with different receptor properties. Instead, the change in Ca(2+) permeability matches the time course of post-transcriptional RNA editing of GluR5 at the Q/R site within the pore of the channel, indicating that the change is probably caused by developmentally regulated RNA editing. We also report that, on the basis of the strong correlation of receptor expression with expression of the surface markers LA4, isolectin B4, and LD2, kainate receptors are present on C-fiber-type neurons projecting to lamina II of spinal cord dorsal horn. These results raise the possibility that kainate receptors in their Ca(2+)-permeable form serve a developmental role in synapse formation between this population of C-fibers and their targets in the spinal cord dorsal horn. Thereafter, the receptors may serve a new function that does not require Ca(2+) permeability
— id: 38393, year: 2001, vol: 21, page: 4572, stat: Journal Article,

Activation of Trk neurotrophin receptors in the absence of neurotrophins
Lee FS; Chao MV
2001 Mar 13;98(6):3555-3560, Proceedings of the National Academy of Sciences of the United States of America
Neurotrophins regulate neuronal cell survival and synaptic plasticity through activation of Trk receptor tyrosine kinases. Binding of neurotrophins to Trk receptors results in receptor autophosphorylation and downstream phosphorylation cascades. Here, we describe an approach to use small molecule agonists to transactivate Trk neurotrophin receptors. Activation of TrkA receptors in PC12 cells and TrkB in hippocampal neurons was observed after treatment with adenosine, a neuromodulator that acts through G protein-coupled receptors. These effects were reproduced by using the adenosine agonist CGS 21680 and were counteracted with the antagonist ZM 241385, indicating that this transactivation event by adenosine involves adenosine 2A receptors. The increase in Trk activity could be inhibited by the use of the Src family-specific inhibitor, PP1, or K252a, an inhibitor of Trk receptors. In contrast to other G protein-coupled receptor transactivation events, adenosine used Trk receptor signaling with a longer time course. Moreover, adenosine activated phosphatidylinositol 3-kinase/Akt through a Trk-dependent mechanism that resulted in increased cell survival after nerve growth factor or brain-derived neurotrophic factor withdrawal. Therefore, adenosine acting through the A(2A) receptors exerts a trophic effect through the engagement of Trk receptors. These results provide an explanation for neuroprotective actions of adenosine through a unique signaling mechanism and raise the possibility that small molecules may be used to elicit neurotrophic effects for the treatment of neurodegenerative diseases
— id: 38399, year: 2001, vol: 98, page: 3555, stat: Journal Article,

The uniqueness of being a neurotrophin receptor
Lee FS; Kim AH; Khursigara G; Chao MV
2001 Jun;11(3):281-286, Current opinion in neurobiology
Neurotrophins rely on Trk tyrosine kinase and p75 receptors for signal transduction. Recently, other roles for these receptors have been identified. Many questions have been raised about the mechanism by which these receptors mediate diverse cellular functions. Studies indicate a great deal of neurotrophin signaling specificity may stem from ligand-receptor selectivity and intracellular protein recruitment
— id: 38395, year: 2001, vol: 11, page: 281, stat: Journal Article,

Cell cycle regulation during mouse olfactory neurogenesis
Legrier, ME; Ducray, A; Propper, A; Chao, M; Kastner, A
2001 Dec;12(12):591-601, Cell growth & differentiation
The development of the nervous system requires a strict control of cell cycle entry and withdrawal. The olfactory epithelium (OE) is noticeable by its ability to yield new neurons not only during development but also continuously during adulthood. The aim of our study was to investigate, by biochemical and immunohistochemical methods, which cell cycle regulators are involved in the control of neuron production during OE development and maturity. At birth, olfactory neural progenitors, the basal cells, exhibited a high mitogenic and neurogenic activity, decreasing in the following weeks together with the drop in expression of several cell cycle regulators. p27Kip1 and p18Ink4c, at birth, were expressed in the whole basal cell layer, whereas p16Ink4a, p19Ink4d, and p21Cip1 were rather located in differentiating or mature neurons. CDK inhibitors may thus act sequentially during this developmental neurogenic process. By comparison, in the adult OE, in which most neural precursors were quiescent, these cells still exhibited p18Ink4c expression but only occasionally p27Kip1 expression. It suggests that p18Ink4c may contribute to maintain basal cells in a quiescent state, whereas p27Kip1 expression in these cells may be rather linked to their neurogenic activity, which declines with age. In keeping with this hypothesis, transgenic mice that lacked p27Kip1 expression displayed a higher rate of cell proliferation versus differentiation in their OE. In these mice, a down-regulation of positive cell cycle regulators was observed that may contribute to compensate for the absence of p27Kip1. Taken together, the present data suggest distinct functions for CDK inhibitors, either in the control of cell cycle exit and differentiation during neurogenesis (respectively, p27Kip1 and p19Ink4d) or in the maintenance of a quiescent state in neural progenitors (p18Ink4c) or neurons (p21Cip1) in adults
— id: 28195, year: 2001, vol: 12, page: 591, stat: Journal Article,

GIPC and GAIP form a complex with TrkA: a putative link between G protein and receptor tyrosine kinase pathways
Lou X; Yano H; Lee F; Chao MV; Farquhar MG
2001 Mar;12(3):615-627, Molecular biology of the cell
NGF initiates the majority of its neurotrophic effects by promoting the activation of the tyrosine kinase receptor TrkA. Here we describe a novel interaction between TrkA and GIPC, a PDZ domain protein. GIPC binds to the juxtamembrane region of TrkA through its PDZ domain. The PDZ domain of GIPC also interacts with GAIP, an RGS (regulators of G protein signaling) protein. GIPC and GAIP are components of a G protein-coupled signaling complex thought to be involved in vesicular trafficking. In transfected HEK 293T cells GIPC, GAIP, and TrkA form a coprecipitable protein complex. Both TrkA and GAIP bind to the PDZ domain of GIPC, but their binding sites within the PDZ domain are different. The association of endogenous GIPC with the TrkA receptor was confirmed by coimmunoprecipitation in PC12 (615) cells stably expressing TrkA. By immunofluorescence GIPC colocalizes with phosphorylated TrkA receptors in retrograde transport vesicles located in the neurites and cell bodies of differentiated PC12 (615) cells. These results suggest that GIPC, like other PDZ domain proteins, serves to cluster transmembrane receptors with signaling molecules. When GIPC is overexpressed in PC12 (615) cells, NGF-induced phosphorylation of mitogen-activated protein (MAP) kinase (Erk1/2) decreases; however, there is no effect on phosphorylation of Akt, phospholipase C-gamma1, or Shc. The association of TrkA receptors with GIPC and GAIP plus the inhibition of MAP kinase by GIPC suggests that GIPC may provide a link between TrkA and G protein signaling pathways
— id: 38398, year: 2001, vol: 12, page: 615, stat: Journal Article,

Tyrosine phosphorylation of p190 RhoGAP by Fyn regulates oligodendrocyte differentiation
Wolf RM; Wilkes JJ; Chao MV; Resh MD
2001 Oct;49(1):62-78, Journal of neurobiology
During development of the central nervous system, oligodendrocyte progenitor cells differentiate into mature myelinating cells. The molecular signals that promote this process, however, are not well defined. One molecule that has been implicated in oligodendrocyte differentiation is the Src family kinase Fyn. In order to probe the function of Fyn in this system, a yeast two hybrid screen was performed. Using Fyn as bait, p190 RhoGAP was isolated in the screen of an oligodendrocyte cDNA library. Coimmunoprecipitation and in vitro binding assays verified that p190 RhoGAP bound to the Fyn SH2 domain. Phosphorylation of p190 required active Fyn tyrosine kinase and was increased threefold upon differentiation of primary oligodendrocytes. Moreover, complex formation between p190 and p120 RasGAP occurred in differentiated oligodendrocytes. p190 RhoGAP activity is known to regulate the RhoGDP:RhoGTP ratio. Indeed, expression of dominant negative Rho in primary oligodendrocytes caused a hyperextension of processes. Conversely, constitutively activated Rho caused reduced process formation. These findings define a pathway in which Fyn activity regulates the phosphorylation of p190, leading to an increase in RhoGAP activity with a subsequent increase in RhoGDP, which in turn, regulates the morphological changes that accompany oligodendrocyte differentiation
— id: 38390, year: 2001, vol: 49, page: 62, stat: Journal Article,

Association of Trk neurotrophin receptors with components of the cytoplasmic dynein motor
Yano H; Lee FS; Kong H; Chuang J; Arevalo J; Perez P; Sung C; Chao MV
2001 Feb 1;21(3):RC125-RC125, Journal of neuroscience
Nerve growth factor (NGF) initiates its trophic effects by long-range signaling through binding, internalization, and transport of a ligand-receptor complex from the axon terminal to the cell body. However, the mechanism by which retrograde transport of NGF takes place has not been elucidated. Here we describe an interaction between the Trk receptor tyrosine kinase and a 14 kDa light chain of cytoplasmic dynein. After transfection in human embryonic kidney 293 cells, this 14 kDa dynein light chain was found to bind to TrkA, TrkB, and TrkC receptors. Mapping experiments indicated that the 14 kDa dynein light chain binds to the distal region of the TrkA juxtamembrane domain. Coimmunoprecipitation experiments in vivo indicate that Trk receptors are in a complex with the 14 kDa light chain and 74 kDa intermediate chain of dynein. Confirming the physiological relevance of this association, a marked accumulation of Trk with the 14 kDa and the 74 kDa dynein components was observed after ligation of the sciatic nerve. The association of Trk receptors with components of cytoplasmic dynein suggests that transport of neurotrophins during vesicular trafficking may occur through a direct interaction of the Trk receptor with the dynein motor machinery
— id: 21256, year: 2001, vol: 21, page: RC125, stat: Journal Article,

p21cip1 is required for the differentiation of oligodendrocytes independently of cell cycle withdrawal
Zezula J; Casaccia-Bonnefil P; Ezhevsky SA; Osterhout DJ; Levine JM; Dowdy SF; Chao MV; Koff A
2001 Jan;2(1):27-34, EMBO reports
Differentiation of most cell types requires both establishment of G1 arrest and the induction of a program related to achieving quiescence. We have chosen to study the differentiation of oligodendrocyte cells to determine the role of p27 and p21 in this process. Here we report that both p27 and p21 are required for the appropriate differentiation of these cells. p27 is required for proper withdrawal from the cell cycle, p21 is not. Instead, p21 is required for the establishment of the differentiation program following growth arrest. Similar observations were made in vivo. We show that p21-/- cells withdraw from the cell cycle similar to wild-type cells; however, early in animal life, the brain is hypomyelinated, inferring that the loss of p21 delayed myelination in the cerebellum. We found that we could complement or bypass the differentiation failure in p21-/- cells with either PD98059, an inhibitor of Mek1, or by transducing them with a tat-p16ink4a protein. We concluded that the two cdk inhibitors serve non-redundant roles in this program of differentiation, with p27 being responsible for arrest and p21 having a function in differentiation independent of its ability to control exit from the cell cycle
— id: 38397, year: 2001, vol: 2, page: 27, stat: Journal Article,

TrkA immunoglobulin-like ligand binding domains inhibit spontaneous activation of the receptor
Arevalo JC; Conde B; Hempstead BL; Chao MV; Martin-Zanca D; Perez P
2000 Aug;20(16):5908-5916, Molecular & cellular biology
The extracellular region of the nerve growth factor (NGF) receptor, TrkA, contains two immunoglobulin (Ig)-like domains that are required for specific ligand binding. We have investigated the possible role of these two Ig-like domains in receptor dimerization and activation by using different mutants of the TrkA extracellular region. Deletions of each Ig-like domain, of both, and of the entire extracellular region were made. To probe the structural constraints on ligand-independent receptor dimerization, chimeric receptors were generated by swapping the Ig-like domains of the TrkA receptor for the third or fourth Ig-like domain of c-Kit. We also introduced single-amino-acid changes in conserved residues within the Ig-like domains of TrkA. Most of these TrkA variants did not bind NGF, and their expression in PC12nnr5 cells, which lack endogenous TrkA, promoted ligand-independent neurite outgrowth. Some TrkA mutant receptors induced malignant transformation of Rat-1 cells, as assessed by measuring proliferation in the absence of serum, anchorage-independent growth, and tumorigenesis in nude mice. These mutants exhibited constitutive phosphorylation and spontaneous dimerization consistent with their biological activities. Our data suggest that spontaneous dimerization of TrkA occurs when the structure of the Ig-like domains is altered, implying that the intact domains inhibit receptor dimerization in the absence of NGF
— id: 14639, year: 2000, vol: 20, page: 5908, stat: Journal Article,

Trophic factors: An evolutionary cul-de-sac or door into higher neuronal function?
Chao MV
2000 Feb 1;59(3):353-355, Journal of neuroscience research
Trophic factors, such as the neurotrophins, CNTF, and GDNF, represent unique families of proteins that are essential for the development of the vertebrate nervous system. Surprisingly, there is little evidence to date that these proteins exist in Drosophila melanogaster and Caenorhabditis elegans, even though other polypeptide growth factors, such as EGF, FGF, and insulin, are conserved in these species. For the neurotrophins, the evolution of NGF, BDNF, NT-3, and NT-4 as a family implies that these signaling molecules may be involved in mediating additional neural activities, such as learning, memory, and behavior. Indeed, there is abundant evidence now that BDNF is involved in synapse modification, neurotransmitter release, long-term potentiation, and mechanosensation. The widening scope of neurotrophin action will require more physiological, genomic, and integrative approaches to understand fully the mechanisms by which survival factors can mediate so many diverse effects.
— id: 11831, year: 2000, vol: 59, page: 353, stat: Journal Article,

Apoptotic signaling through the beta -adrenergic receptor. A new Gs effector pathway
Gu C; Ma YC; Benjamin J; Littman D; Chao MV; Huang XY
2000 Jul 7;275(27):20726-20733, Journal of biological chemistry
Stimulation of beta-adrenergic receptor normally results in signaling by the heterotrimeric G protein G(s), leading to the activation of adenylyl cyclase, production of cAMP, and activation of cAMP-dependent protein kinase (PKA). Here we report that cell death of thymocytes can be induced after stimulation of beta-adrenergic receptor, or by addition of exogenous cAMP. Apoptotic cell death in both cases was observed with the appearance of terminal deoxynucleotidyl transferase-mediated UTP end labeling reactivity and the activation of caspase-3 in S49 T cells. Using thymocytes deficient in either Galpha(s) or PKA, we find that engagement of beta-adrenergic receptors initiated a Galpha(s)-dependent, PKA-independent pathway leading to apoptosis. This alternative pathway involves Src family tyrosine kinase Lck. Furthermore, we show that Lck protein kinase activity can be directly stimulated by purified Galpha(s). Our data reveal a new signaling pathway for Galpha(s), distinct from the classical PKA pathway, that accounts for the apoptotic action of beta-adrenergic receptors
— id: 14641, year: 2000, vol: 275, page: 20726, stat: Journal Article,

Biological role of nervous system specific receptor tyrosine phosphatase revealed by analysis of RPTPbeta knockout mice
Harroch, S; Casaccia-Bonnefil, P; Lafaille, J; Chao, M; Custer, A; Shrager, P; Rosenbluth, J; Schlessinger, J
2000 Nov 04-09;26(1-2):?-? Abstract #4018, Abstracts (Society for Neuroscience)
Cell survival, differentiation and migration relies heavily on protein tyrosine phosphorylation of intracellular proteins and is regulated by the activity of kinases and phosphatases. RPTPbeta is a receptor-like protein tyrosine phosphatases composed of an extracellular domain, a single transmembrane domain and a cytoplasmic portion that contains two tyrosine phosphatase domains. Three different isoforms of RPTPbeta are expressed as a result of alternative splicing: a short and a long form that differ by the presence of the spacer region of the extracellular domain and a secreted form lacking phosphatase activity, also known as 3F8 proteoglycan or phosphacan. The pattern of RPTPbeta expression in the developing nervous system, is highly suggestive of its potential role in glial cell differentiation and survival. RPTPbeta is expressed in oligodendrocytes, Schwann cells and astrocytes. Both full-length RPTPbeta phosphatase and phosphacan isoforms are predominantly expressed as chondroitin sulfate proteoglycans in the subventricular zone and in glial cells from E8 throughout development and in the adult nervous system. RPTPbeta forms a ternary complex with contactin and Caspr, localized to the paranodal junctions. It has been suggested that the interaction between RPTPbeta and contactin may mediate bi-directional cellular signals between neurons and glial cells implicating a potential role of RPTPbeta in paranode formation. To investigate RPTPbeta functions, we have generated animals lacking RPTPbeta and demonstrate that these animals lack the three forms of RPTPbeta. Our results provide indications of a role of RPTPbeta in oligodendrocyte survival/differentiation and also an increased axonal sensitivity in disease states. We will discuss the role of RPTPbeta in oligodendrocyte differentiation and axonal growth and its implication for repair after injury
— id: 16057, year: 2000, vol: 26, page: ?, stat: Journal Article,

Biological role of nervous system specific receptor tyrosine phosphatase revealed by analysis of R
Harroch, S; Casaccia-Bonnefil, P; Lafaille, J; Chao, M; Rosenbluth, J; Verdugo-Garcia, JM; Schlessinger, J
2000 DEC ;11(2):401A-401A, Molecular biology of the cell
— id: 55212, year: 2000, vol: 11, page: 401A, stat: Journal Article,

Fyn tyrosine kinase signaling in oligodendrocyte differentiation
Osterhout, DJ; Chao, MV
2000 FEB ;74(2):S60-S60, Journal of neurochemistry
— id: 54745, year: 2000, vol: 74, page: S60, stat: Journal Article,

Cell cycle control of Schwann cell proliferation: role of cyclin-dependent kinase-2
Tikoo R; Zanazzi G; Shiffman D; Salzer J; Chao MV
2000 Jun 15;20(12):4627-4634, Journal of neuroscience
Schwann cell proliferation is regulated by multiple growth factors and axonal signals. However, the molecules that control growth arrest of Schwann cells are not well defined. Here we describe regulation of the cyclin-dependent kinase-2 (CDK2) protein, an enzyme that is necessary for the transition from G1 to S phase. Levels of CDK2 protein were elevated in proliferating Schwann cells cultured in serum and forskolin. However, when cells were grown with either serum-free media or at high densities, CDK2 levels declined to low levels. The decrease in CDK2 levels was associated with growth arrest of Schwann cells. The modulation of CDK2 appears to be regulated at the transcriptional level, because CDK2 mRNA levels and its promoter activity both decline during cell cycle arrest. Furthermore, analysis of the CDK2 promoter suggests that Sp1 DNA binding sites are essential for maximal activation in Schwann cells. Together, these data suggest that CDK2 may represent a significant target of developmental signals that regulate Schwann cell proliferation and that this regulation is mediated, in part, through regulation of Sp1 transcriptional activity
— id: 14640, year: 2000, vol: 20, page: 4627, stat: Journal Article,

Neurotrophin receptor structure and interactions
Yano H; Chao MV
2000 Mar;74(2-3):253-260, Pharmaceutica acta helvetiae
Although ligand-induced dimerization or oligomerization of receptors is a well established mechanism of growth factor signaling, increasing evidence indicates that biological responses are often mediated by receptor trans-signaling mechanisms involving two or more receptor systems. These include G protein-coupled receptors, cytokine, growth factor and trophic factor receptors. Greater flexibility is provided when different signaling pathways are merged through multiple receptor signaling systems. Trophic factors exemplified by NGF and its family members, ciliary neurotrophic factor (CNTF) and glial derived neurotrophic factor (GDNF) all utilize increased tyrosine phosphorylation of cellular substrates to mediate neuronal cell survival. Actions of the NGF family of neurotrophins are not only dictated by ras activation through the Trk family of receptor tyrosine kinases, but also a survival pathway defined by phosphatidylinositol-3-kinase activity (Yao and Cooper, 1995), which gives rise to phosphoinositide intermediates that activate the serine/threonine kinase Akt/PKB (Dudek et al., 1997). Induction of the serine-threonine kinase activity is critical for cell survival, as well as cell proliferation. Hence, for many trophic factors, multiple proteins constitute a functional multisubunit receptor complex that activates ras-dependent and ras-independent intracellular signaling. The NGF receptors provide an example of bidirectional crosstalk. In the presence of TrkA receptors, p75 can participate in the formation of high affinity binding sites and enhanced neurotrophin responsiveness leading to a survival or differentiation signal. In the absence of TrkA receptors, p75 can generate, in only specific cell populations, a death signal. These activities include the induction of NF kappa B (Carter et al., 1996); the hydrolysis of sphingomyelin to ceramide (Dobrowsky et al., 1995); and the pro-apoptotic functions attributed to p75. Receptors are generally drawn and viewed as isolated integral membrane proteins which span the lipid bilayer, with signal transduction proceeding in a linear step-wise fashion. There are now numerous examples which indicate that each receptor acts not only in a linear, independent manner, but can also influence the activity of other cell surface receptors, either directly or through signaling intermediates. Which step and which intermediates are utilized for crosstalk between the receptors is a critical question. For neurotrophins, their primary function in sustaining the viability of neurons is counterbalanced by a receptor mechanism to eliminate cells by an apoptotic mechanism. It is conceivable that this bidirectional system may be utilized selectively during development and in neurodegenerative diseases
— id: 11695, year: 2000, vol: 74, page: 253, stat: Journal Article,

Association of the Abl tyrosine kinase with the Trk nerve growth factor receptor
Yano H; Cong F; Birge RB; Goff SP; Chao MV
2000 Feb 1;59(3):356-364, Journal of neuroscience research
Nerve growth factor (NGF) initiates the majority of its biological effects by promoting the dimerization and activation of the tyrosine kinase receptor TrkA. In addition to rapid increases in the phosphorylation of phosphatidylinositol 3'-kinase (PI 3-kinase) and phospholipase C-gamma and increased ras activity, phosphorylation of c-Crk and paxillin proteins has been observed upon TrkA activation. The c-Abl tyrosine kinase is involved in the control of the axonal cytoskeleton and is known to interact with c-Crk proteins. Here we have tested the possibility that TrkA receptors might form an association with the c-Abl protein. After transfection in 293T cells, TrkA and c-Abl kinases could be coimmunoprecipitated. This interaction did not require TrkA receptors to be autophosphorylated. Mapping analysis indicated that the region of c-Abl association was confined to the juxtamembrane region of TrkA. The interaction of c-Abl with TrkA was also observed in differentiated pheochromocytoma PC12 cells. These results suggest that c-Abl may be recruited to the NGF receptor complex and be involved in regulating specific phosphorylation events that occur during neuronal differentiation.
— id: 11830, year: 2000, vol: 59, page: 356, stat: Journal Article,

Neurotrophins in cell survival/death decisions
Casaccia-Bonnefil P; Gu C; Chao MV
1999 ;468:275-282, Advances in experimental medicine & biology
Neurotrophins are target-derived soluble factors required for neuronal survival. Nerve growth factor (NGF) the founding member of the neurotrophin family, binds to two types of receptors: Trk tyrosine kinase and the p75 neurotrophin receptor, which belongs to the Fas-tumor necrosis factor (TNF) receptor superfamily. Binding of neurotrophins to Trk receptor tyrosine kinases initiate signaling cascades that promote cell survival sand differentiation. In contrast, p75 NGFR has been shown to modulate the susceptibility to death of selective cellular populations--including differentiated rat oligodendrocytes--in specific conditions. Notably, NGF effect on viability was only observed in fully differentiated oligodendrocytes and not in oligodendrocyte progenitor cells. The effect of p75 activation on oligodendrocyte survival correlates with increased activity of the stress related kinase JNK-1 and cleavage of specific caspases. Indeed, activation of additional stress pathways or impairment of survival signals may be required for p75 mediated activation of cell death execution programs. Interestingly, co-expression of the TrkA receptor in the same cell type abolishes the JNK-1 mediated death signal and induces MAP kinase activity, resulting in cell survival. This suggests that glial cell survival results from a balance between positive and negative regulators modulated by selective signalling pathways by tyrosine kinases and cytokine receptors
— id: 11864, year: 1999, vol: 468, page: 275, stat: Journal Article,

p75 neurotrophin receptor as a modulator of survival and death decisions
Casaccia-Bonnefil P; Gu C; Khursigara G; Chao MV
1999 May 15-Jun 1;45(4-5):217-224, Microscopy research & technique
The p75 receptor is the founding member of the TNF receptor superfamily. Members in this receptor family share a common cysteine motif repeated two to six times that serves as the ligand binding domain. In addition, several members contain a cytoplasmic region designated the death domain. The neurotrophins NGF, BDNF, NT-3, and NT-4 each bind to the p75 receptor and also more selectively to members of the Trk family of receptor tyrosine kinases. Although the biological functions of p75 have been elusive, recent experimental evidence supports an involvement of this receptor in apoptosis. This presents a counter-intuitive function for neurotrophins, which are normally required for the survival of neurons during development. The life-and-death decisions by neurotrophins appear to be governed by the level of expression and signaling activities of the p75 and Trk tyrosine kinase receptors and their downstream effector molecules. The generation of the correct number of cells in the nervous system is a highly controlled and coordinated process that is the consequence of cell proliferation and cell death decisions. The appropriate number of neuronal and glial cells formed during development guarantees the establishment of proper innervation and functional synaptic connections. One common mechanism to account for the number of viable cells is the ability to form ligand-receptor complexes that promote cell survival under conditions of limiting concentrations of trophic factors. Another diametrically opposed mechanism is to produce ligand-receptor interactions that can activate programmed cell death directly
— id: 56448, year: 1999, vol: 45, page: 217, stat: Journal Article,

Loss of p27Kip1 function results in increased proliferative capacity of oligodendrocyte progenitors but unaltered timing of differentiation
Casaccia-Bonnefil P; Hardy RJ; Teng KK; Levine JM; Koff A; Chao MV
1999 Sep;126(18):4027-4037, Development
In many tissues, progenitor cells permanently withdraw from the cell cycle prior to commitment towards a differentiated phenotype. In the oligodendrocyte lineage a counting mechanism has been proposed, linking the number of cell divisions to growth arrest and differentiation. A direct prediction of this model is that an increase in the number of cell divisions would result in a delayed onset of differentiation. Since the cell cycle inhibitor p27Kip1 is an essential component of the machinery leading to oligodendrocyte progenitor growth arrest, we examined the temporal relationship between cell cycle withdrawal and expression of late differentiation markers in vivo, in mice carrying a targeted deletion in the p27Kip1 gene. Using bromodeoxyuridine to label proliferating cells, quaking (QKI) to identify embryonic glial progenitors, NG2 to identify neonatal oligodendrocyte progenitors, and myelin basic protein to label differentiated oligodendrocytes, we found an increased number of proliferating QKI- and NG2-positive cells in germinal zones of p27Kip1(-/-) mice at the peak of gliogenesis. However, no delay was observed in these mice in the appearance of the late differentiation marker myelin basic protein in the developing corpus callosum and cerebellum. Significantly, a decrease in cyclin E levels was observed in the brain of p27Kip1 null mice coincident with oligodendrocyte growth arrest. We conclude that two distinct modalities of growth arrest occur in the oligodendrocyte lineage: a p27Kip1-dependent mechanism of growth arrest affecting proliferation in early phases of gliogenesis, and a p27Kip1-independent event leading to withdrawal from the cell cycle and differentiation
— id: 6185, year: 1999, vol: 126, page: 4027, stat: Journal Article,

Mechanisms of regulation of oligodendrocyte cell number
Casaccia-Bonnefil, P; Hardy, R; Levine, J; Chao, MV
1999 JUL ;73(12):S163-S163, Journal of neurochemistry
— id: 53995, year: 1999, vol: 73, page: S163, stat: Journal Article,

Role of cell cycle modulators of G1/S transition in oligodendrocyte progenitor development
Casaccia-Bonnefil, P; Ze, zula J; Koff, A; Chao, M V
1999 Oct 23-28;25(1-2):9-9, Abstracts (Society for Neuroscience)
— id: 15870, year: 1999, vol: 25, page: 9, stat: Journal Article,

Differential association of phosphatidylinositol-5-phosphate 4-kinase with the EGF/ErbB family of receptors
Castellino AM; Chao MV
1999 Mar;11(3):171-177, Cellular signalling
Phosphatidylinositol-5-phosphate 4-kinase (PIP4K) is required for the production of phosphoinositol-4,5-hisphosphate (PIP2), which has been closely associated with growth factor signalling. Here we have tested the possibility that phosphoinositide kinases may be take part in signal transduction through interactions with the epidermal growth factor (EGF) receptor and the ErbB family of tyrosine kinase receptors. Interactions of the Type IIbeta isoform of PIP4K were observed with the EGF receptor family members in a number of diverse cell lines, including A431, PC12 and MCF7 cells but not with the N6F TrkA receptor. Co-immunoprecipitation experiments indicate that PIP4K interacts with not only the EGF receptor, but also selectively with members of the ErbB tyrosine kinase family. These results demonstrate another enzyme substrate for EGF receptors that facilitates the production of phosphoinositides at the cell membrane
— id: 14642, year: 1999, vol: 11, page: 171, stat: Journal Article,

Identification of a zinc finger protein whose subcellular distribution is regulated by serum and nerve growth factor
Chittka A; Chao MV
1999 Sep 14;96(19):10705-10710, Proceedings of the National Academy of Sciences of the United States of America
A subclass of zinc finger proteins containing a unique protein motif called the positive regulatory (PR) domain has been described. The members include the PRDI-BF1/Blimp-1 protein, the Caenorhabditis elegans egl-43 and EVI1 gene products, and the retinoblastoma interacting protein RIZ. Here we describe a member of this family, SC-1, that exhibits several distinctive features. First, SC-1 interacts with the p75 neurotrophin receptor and is redistributed from the cytoplasm to the nucleus after nerve growth factor (NGF) treatment of transfected COS cells. The translocation of SC-1 to the nucleus was specific for p75, as NGF binding to the TrkA receptor did not lead to nuclear localization of SC-1. Thus, SC-1 provides a downstream transducer for the effects of NGF through the p75 neurotrophin receptor. Under normal growth conditions, SC-1 was found predominantly in the cytoplasm. On serum-starvation, SC-1 also translocated into the nucleus. A direct correlation between nuclear expression of SC-1 with the loss of BrdUrd incorporation was observed. These results imply that SC-1 may be involved in events associated with growth arrest
— id: 57539, year: 1999, vol: 96, page: 10705, stat: Journal Article,

Up-regulated p75(NTR) neurotrophin receptor on glial cells in MS plaques
Dowling, P; Ming, X; Raval, S; Husar, W; Casaccia-Bonnefil, P; Chao, M; Cook, S; Blumberg, B
1999 NOV 10 ;53(8):1676-1682, Neurology
To investigate the expression of the neurotrophin receptor p75(NTR) On glial cells within MS plaques. Background: In recent studies on the pathogenesis of MS white matter plaques, we found large populations of inflammatory and resident glial cells, including oligodendrocytes undergoing cell death, and identified increased expression of Fas receptor and ligand death pathway signaling molecules on the same glial cell types. In another study, the p75(NTR) was shown to induce apoptotic death of maturing oligodendrocytes when exposed to NGF in vitro. Methods: We used immunohistochemistry and in situ reverse-transcription PCR to detect p75(NTR) expression on inflammatory and resident glial cells in MS plaques and used TUNEL staining for fragmented DNA to detect cell death. Results: Upregulated p75(NTR) messenger RNA and protein were demonstrated in both oligodendrocytes and microglia/macrophages in MS plaques but not in control white matter. However, only a fraction of p75(NTR) expressing oligodendrocytes was also stained by TUNEL. Conclusions: Glial cell expression of p75(NTR) receptor is up-regulated during MS plaque formation. The exact role of this receptor in glial cell death and/or survival in MS remains to be elucidated
— id: 53850, year: 1999, vol: 53, page: 1676, stat: Journal Article,

Oligodendrocyte apoptosis mediated by caspase activation
Gu C; Casaccia-Bonnefil P; Srinivasan A; Chao MV
1999 Apr 15;19(8):3043-3049, Journal of neuroscience
Treatment with NGF causes long-term cultures of oligodendrocytes to die via a yet undefined mechanism mediated by the p75 neurotrophin receptor. The p75 receptor belongs to the TNF receptor superfamily of molecules, which includes Fas and p55 TNF receptors. The Fas and TNF receptors use adaptor molecules to recruit and activate caspase-8 to the receptor. Using a combination of immunohistochemical and Western blotting assays, we have examined caspase activity during NGF-induced apoptosis. Interestingly, although caspase-1 [interleukin-1beta-converting enzyme (ICE)], caspase-2, caspase-3, and caspase-8 were expressed in oligodendrocytes, only caspase-1, -2, and -3 were activated after NGF treatment, whereas caspase-8 was not. These data suggest that the mechanism of apoptosis by NGF through the p75 receptor is different from TNF and Fas-mediated killing. gamma Radiation of oligodendrocytes also activated a similar subset of caspases as NGF, indicating that NGF-induced oligodendrocyte apoptosis uses a similar cell death execution mechanism as injury models. This consolidates a potential role of the p75 neurotrophin receptor during stress and inflammatory conditions
— id: 8514, year: 1999, vol: 19, page: 3043, stat: Journal Article,

Association of the p75 neurotrophin receptor with TRAF6
Khursigara G; Orlinick JR; Chao MV
1999 Jan 29;274(5):2597-2600, Journal of biological chemistry
In addition to the Trk tyrosine kinase receptors, neurotrophins also bind to a second receptor, p75, a member of the tumor necrosis factor receptor superfamily. Several signaling pathways have been implicated for p75 in the absence of Trk receptors, including induction of NF-kappaB and c-Jun kinase activities and increased production of ceramide. However, to date, the mechanisms by which the p75 receptor initiates intracellular signal transduction have not been defined. Here we report a specific interaction between p75 and TRAF6 (tumor necrosis factor receptor-associated factor-6) after transient transfection in HEK293T cells. The interaction was ligand-dependent and maximal at 100 ng/ml of nerve growth factor (NGF). Other neurotrophins also promoted the association of TRAF6 with p75 but to a lesser extent. The binding of TRAF6 was localized to the juxtamembrane region of p75 by co-immunoprecipitation and Western blotting. To assess the functional significance of this interaction, we have tested responses in cultured Schwann cells that express p75 and TRAF6. An NGF-mediated increase in the nuclear localization of the p65 subunit of NF-kappaB could be blocked by the introduction of a dominant negative form of TRAF6 in Schwann cells. These results indicate that TRAF6 can potentially function as a signal transducer for NGF actions through the p75 receptor
— id: 7369, year: 1999, vol: 274, page: 2597, stat: Journal Article,

Effect of TrkA and p75 NGF receptors on Traf-6 binding and activation
Khursigara, G; Wagner, J; Chao, M V
1999 Oct 23-28;25(1-2):2024-2024, Abstracts (Society for Neuroscience)
— id: 15842, year: 1999, vol: 25, page: 2024, stat: Journal Article,

Differential effects of the intracellular domains of the p75 neurotrophin receptor and the Fas receptor on apoptosis
Kim, A H; Kong, H; Orlinick, J R; Chao, M V
1999 Oct 23-28;25(1-2):1527-1527, Abstracts (Society for Neuroscience)
— id: 15856, year: 1999, vol: 25, page: 1527, stat: Journal Article,

A comparison of the cytoplasmic domains of the Fas receptor and the p75 neurotrophin receptor
Kong H; Kim AH; Orlinick JR; Chao MV
1999 Nov;6(11):1133-1142, Cell death & differentiation
The p75 neurotrophic receptor (p75) shares structural features with the Fas receptor (FasR). Both receptors contain extracellular cysteine-rich repeats, a single transmembrane domain, and intracellular death domains. However, it has not been clearly established whether their death domains are equivalent in their ability to mediate apoptosis. To understand better the role of p75 during apoptosis, we constructed chimeric receptors that contained the extracellular portion of the FasR and the intracellular portion of p75. These chimeric receptors, one containing the p75 transmembrane domain and the other containing the FasR transmembrane portion, as well as wild-type p75 and Fas receptors, were transiently transfected into human U373 glioma cells and human embryonic kidney 293 cells (293 cells), which are both responsive to Fas-mediated apoptosis. Whereas expression of FasR was sufficient to induce apoptosis in U373 and 293 cells, expression of p75 and the chimeric receptors induced only minimal levels of cell death compared to FasR. The results indicate that the magnitudes of FasR- and p75-induced killing are different and suggest that the death domain of p75 does not function in the same manner as the FasR death domain
— id: 11917, year: 1999, vol: 6, page: 1133, stat: Journal Article,

Identification of a novel, neuron-specific, neurotrophin-responsive transmembrane protein
Kong, H; Boulter, J; Lai, C; Chao, M
1999 Oct 23-28;25(1-2):1782-1782, Abstracts (Society for Neuroscience)
— id: 15820, year: 1999, vol: 25, page: 1782, stat: Journal Article,

Morphological differentiation of oligodendrocytes requires activation of Fyn tyrosine kinase
Osterhout DJ; Wolven A; Wolf RM; Resh MD; Chao MV
1999 Jun 14;145(6):1209-1218, Journal of cell biology
In the central nervous system, myelination of axons occurs when oligodendrocyte progenitors undergo terminal differentiation and initiate process formation and axonal ensheathment. Although it is hypothesized that neuron-oligodendrocyte contact initiates this process, the molecular signals are not known. Here we find that Fyn tyrosine kinase activity is upregulated very early during oligodendrocyte progenitor cell differentiation. Concomitant with this increase is the appearance of several tyrosine phosphorylated proteins present only in differentiated cells. The increased tyrosine kinase activity is specific to Fyn, as other Src family members are not active in oligodendrocytes. To investigate the function of Fyn activation on differentiation, we used Src family tyrosine kinase inhibitors, PP1 and PP2, in cultures of differentiating oligodendrocyte progenitors. Treatment of progenitors with these compounds prevented activation of Fyn and reduced process extension and myelin membrane formation. This inhibition was reversible and not observed with related inactive analogues. A similar effect was observed when a dominant negative Fyn was introduced in progenitor cells. These findings strongly suggest that activation of Fyn is an essential signaling component for the morphological differentiation of oligodendrocytes
— id: 6138, year: 1999, vol: 145, page: 1209, stat: Journal Article,

A role for Fyn tyrosine kinase in oligodendrocyte differentiation
Osterhout, D J; Chao, M V
1999 Oct 23-28;25(1-2):1765-1765, Abstracts (Society for Neuroscience)
— id: 15821, year: 1999, vol: 25, page: 1765, stat: Journal Article,

Regulation of Fyn tyrosine kinase during oligodendrocyte differentiation
Osterhout, DJ; Chao, MV
1999 NOV ;10(5):365A-365A, Molecular biology of the cell
— id: 53781, year: 1999, vol: 10, page: 365A, stat: Journal Article,

The molecular basis for apoptotic defects in patients with CD95 (Fas/Apo-1) mutations [published erratum appears in J Clin Invest 1999 Apr;103(7):1099]
Vaishnaw AK; Orlinick JR; Chu JL; Krammer PH; Chao MV; Elkon KB
1999 Feb;103(3):355-363, Journal of clinical investigation
Heterozygous mutations of the receptor CD95 (Fas/Apo-1) are associated with defective lymphocyte apoptosis and a clinical disease characterized by lymphadenopathy, splenomegaly, and systemic autoimmunity. From our cohort of 11 families, we studied eight patients to define the mechanisms responsible for defective CD95-mediated apoptosis. Mutations in and around the death domain of CD95 had a dominant-negative effect that was explained by interference with the recruitment of the signal adapter protein, FADD, to the death domain. The intracellular domain (ICD) mutations were associated with a highly penetrant Canale-Smith syndrome (CSS) phenotype and an autosomal dominant inheritance pattern. In contrast, mutations affecting the CD95 extracellular domain (ECD) resulted in failure of extracellular expression of the mutant protein or impaired binding to CD95 ligand. They did not have a dominant-negative effect. In each of the families with an ECD mutation, only a single individual was affected. These observations were consistent with differing mechanisms of action and modes of inheritance of ICD and ECD mutations, suggesting that individuals with an ECD mutation may require additional defect(s) for expression of CSS
— id: 7460, year: 1999, vol: 103, page: 355, stat: Journal Article,

"The molecular basis for apoptotic defects in patients with CD95 (Fas/Apo-1) mutations (vol 103, pg 355, 1999)"
Vaishnaw, AK; Orlinick, JR; Chu, JL; Krammer, PH; Chao, MV; Elkon, KB
1999 APR ;103(7):1099-1099, Journal of clinical investigation
— id: 105086, year: 1999, vol: 103, page: 1099, stat: Journal Article,

An interaction between the Trk receptor and Dynein light chain, a component of the retrograde motor complex
Yano, H; Lee, F; Kong, H; Arevalo, J C; Perez, P; Sung, C-H; Chao, M V
1999 Oct 23-28;25(1-2):1006-1006, Abstracts (Society for Neuroscience)
— id: 15862, year: 1999, vol: 25, page: 1006, stat: Journal Article,

Functional expression of TrkA receptors in hippocampal neurons
Aibel L; Martin-Zanca D; Perez P; Chao MV
1998 Nov 1;54(3):424-431, Journal of neuroscience research
Nerve growth factor (NGF) initiates its biological effects by promoting the dimerization and activation of the tyrosine kinase receptor TrkA. The requirements for NGF signaling through the TrkA receptor have been defined extensively from studies in immortalized cells, involving transfection of NIH 3T3, COS, and PC12 cells. In the present study, we tested the effects of extracellular and intracellular mutations of TrkA after DNA-mediated transfection in primary cultures of embryonic day 17 hippocampal neurons. We found that the action of the TrkA receptor on neuronal differentiation depends on specific motifs in the extracellular domain and on tyrosine 490 (Y490), the site for SHC protein binding. In contrast with previous observations in a PC12 background, a mutation in the SHC Y490 binding site in TrkA resulted in a loss of NGF-dependent process formation. These results indicate that tyrosine 490 is necessary for neurite outgrowth in hippocampal neurons. Moreover, a constitutively active form of TrkA did not give enhanced responsiveness in hippocampal neurons, indicating that the behavior of TrkA receptors in primary neuronal cells is distinct from that of other cell types
— id: 57090, year: 1998, vol: 54, page: 424, stat: Journal Article,

Neurotrophins: the biological paradox of survival factors eliciting apoptosis
Casaccia-Bonnefil P; Kong H; Chao MV
1998 May;5(5):357-364, Cell death & differentiation
Neurotrophins are target-derived soluble polypeptides required for neuronal survival. Binding of neurotrophins to Trk receptor tyrosine kinases initiate signaling cascades that promote cell survival and differentiation. All family members bind to another receptor (p75NTR), which belongs to the tumor necrosis factor superfamily. Hence, nerve growth factor (NGF) and related trophic factors are unique in that two separate receptor types are utilized. Although the biological function of p75NTR has been elusive, it has been suggested to mediate apoptosis of developing neurons in the absence of Trk receptors. This presents a tantalizing paradigm, in which life-death decisions of cells are dependent upon the expression and action of two different receptors with distinctive signaling mechanisms. In the presence of TrkA receptors, p75 can participate in the formation of high affinity binding sites and enhanced NGF responsiveness leading to a survival signal. In the absence of TrkA receptors, p75 can generate, in only specific cell populations, a death signal. Here we discuss the unique features and implications of this unusual signal transduction system
— id: 56421, year: 1998, vol: 5, page: 357, stat: Journal Article,

Analysis of the subventricular zone of p27Kip null mice: Do committed progenitor cells differ in the modality of growth arrest?
Casaccia-Bonnefil, P; Doetsch, Fiona; Hardy, Rebecca; Alvarez-Buylla, Arturo; Chao, Moses V
1998 Nov 7-12;24(1-2):3-3, Abstracts (Society for Neuroscience)
— id: 15932, year: 1998, vol: 24, page: 3, stat: Journal Article,

Control of glial cell proliferation and differentiation
Chao, Moses V; Osterhout, Donna; Tikoo, Ravi; Casaccia-Bonnefil, Patrizia
1998 Sep 21-23;(22):S2-S2, Neuroscience research. Supplement
— id: 15933, year: 1998, vol: , page: S2, stat: Journal Article,

BRE: a modulator of TNF-alpha action
Gu C; Castellino A; Chan JY; Chao MV
1998 Sep;12(12):1101-1108, FASEB journal
A stress-responsive gene highly expressed in brain and reproductive organs (BRE) is down-regulated after UV irradiation, DNA damaging agents, or retinoic acid treatment. The human BRE gene encodes a mRNA of 1.9 kb, which gives rise to a protein of 383 amino acids with a molecular size of 44 kilodaltons. BRE is not homologous to any known gene and its function has not been defined. Here we report that BRE was identified multiple times in a yeast two-hybrid screen of a murine cerebellar cDNA library, using the juxtamembrane domain of the p55 tumor necrosis factor alpha (TNF) receptor. The interaction between the p55 receptor and BRE was verified by an in vitro biochemical assay by using recombinant fusion proteins and by co-immunoprecipitation of transfected mammalian cells. In the yeast two-hybrid assay, BRE specifically interacted with p55 TNF receptor but not with other TNF family members such as the Fas receptor, the p75 TNF receptor, and p75 neurotrophin receptor. Overexpression of BRE inhibited TNF-induced NFkappaB activation, indicating that the interaction of BRE protein with the cytoplasmic region of p55 TNF receptor may modulate signal transduction by TNF-alpha
— id: 14643, year: 1998, vol: 12, page: 1101, stat: Journal Article,

p75 neurotrophin receptor interacts with Traf-6
Khursigara, G; Chao, MV
1998 NOV ;9(11):432A-432A, Molecular biology of the cell
— id: 53649, year: 1998, vol: 9, page: 432A, stat: Journal Article,

TNF-related ligands and their receptors
Orlinick JR; Chao MV
1998 Sep;10(8):543-551, Cellular signalling
Multicellular organisms have the challenging task of coordinating the activities of many distinct cell types. This coordination is accomplished largely by cell-associated and soluble signalling molecules that act locally or distantly to alter target-cell physiology. The tumour necrosis factor family of cytokines are type II transmembrane proteins that are important regulators of homeostasis and have been implicated as mediators of disease. These molecules serve as ligands for a family of cell-surface receptors termed the tumour necrosis factor/nerve growth factor (TNF/NGF) receptor family. The receptors are type I transmembrane proteins capable of mediating a wide range of responses in vitro and in vivo. Signal transduction is mediated by several newly discovered cytoplasmic proteins that couple these receptors to downstream signalling events. The elucidation and use of spontaneously occurring mutants in TNF-related ligands and receptors in addition to gene-targeting experiments have begun to clarify the diverse biological effects mediated by this superfamily of cytokines
— id: 7725, year: 1998, vol: 10, page: 543, stat: Journal Article,

Fyn tyrosine kinase signaling during oligodendrocyte differentiation
Osterhout, DJ; Wolven, A; Wolf, RM; Resh, MD; Chao, MV
1998 NOV ;9(11):432A-432A, Molecular biology of the cell
— id: 53650, year: 1998, vol: 9, page: 432A, stat: Journal Article,

Reversal of the low-affinity neurotrophin receptor stromal-epithelial expression pattern between benign and malignant human prostate
Papandreou, C N; Bogenrieder, T; Finstad, C L; Freeman, R H; Chao, M V; Albino, A P; Scher, H I; Reuter, V E; Nanus, D M
1998 Nov-Dec;4(6):210-217, Urologic oncology
Reduced expression of the low-affinity p75 neurotrophin receptor (p75(NTR)) occurs in prostate epithelial cells during malignant transformation. Recent studies indicating that the p75(NTR) can transduce signals that induce apoptosis suggest that diminished p75(NTR) in transformed prostate cells may contribute to immortalization. Mutations in the transmembrane domain of the p75(NTR) gene have been associated with decreased p75(NTR) protein expression and may block the ability of the p75(NTR) to induce apoptosis. Therefore, we used Western blot to analyze prostate cancer (PC) cell lines for p75(NTR) protein expression and gene single strand conformation polymorphism (SSCP) analysis and direct DNA sequencing to analyze mutations in the transmembrane domain of the p75(NTR). p75(NTR) Protein was present in all cell lines, and mutations in the p75(NTR) gene were not detected in cDNA derived from any cell line. To define the expression pattern of p75(NTR) in PCs in vivo, we used immunohistochemical techniques to examine tissue specimens from 20 benign, 19 malignant primary, and 14 metastatic prostate specimens. In benign prostate tissues, expression of p75(NTR) was universally detected in basal cells but not in secretory epithelial or stromal cells. In both primary and metastatic PC tissues, p75(NTR) immunoreactivity could not be detected in malignant prostate epithelial cells. However, in contrast to the benign prostate, p75(NTR) protein was expressed in stromal cells surrounding malignant epithelial cells. Stromal p75(NTR) expression was present in 84% (16 of 19) primary and in 86% (12 of 14) metastatic specimens. These data show that in the benign prostate p75(NTR) protein is expressed by basal cells and not stromal cells whereas in malignant prostate p75(NTR) protein is expressed by stromal cells but not prostatic carcinoma cells. Reversal of the p75(NTR) stromal-epithelial pattern of expression between benign and malignant prostate suggests that p75(NTR) may contribute to the development and maintenance of prostate cancer
— id: 145801, year: 1998, vol: 4, page: 210, stat: Journal Article,

Ectopic expression of p27Kip1 in oligodendrocyte progenitor cells results in cell-cycle growth arrest
Tikoo R; Osterhout DJ; Casaccia-Bonnefil P; Seth P; Koff A; Chao MV
1998 Sep 5;36(3):431-440, Journal of neurobiology
Oligodendrocyte differentiation is a complex process believed to be controlled by an intrinsic mechanism associated with cell-cycle arrest. Recently, the cell-cycle inhibitor protein p27 Kip1 has been proposed as a key element in causing growth arrest of oligodendrocyte precursor cells. To investigate the effects of p27 upon oligodendrocyte cell development, we have introduced the p27 cDNA in oligodendrocyte progenitor cells using an adenovirus vector. Progenitor cells normally express low levels of p27. After adenoviral infection and p27 overexpression, progenitor cells were able to undergo cell-cycle arrest, even in the presence of strong mitogens. The effects of p27 were shown to be directly upon cyclin-dependent kinase-2 (CDK2), the protein kinase complex responsible for G1/S transition, as immunodepletion of oligodendrocyte extracts of p27 protein resulted in the activation of CDK2 activity. However, cells that became growth arrested owing to infection with p27 adenovirus did not display conventional oligodendrocyte differentiation markers, such as O4 or O1. Taken together, these data provide mechanistic evidence indicating that p27 is primarily involved in oligodendroglial progenitor proliferation by inhibiting CDK2 activity and inducing oligodendrocyte cell-cycle arrest
— id: 57270, year: 1998, vol: 36, page: 431, stat: Journal Article,

Glial cell growth arrest depends on the relative levels of CDK2 and p27
Tikoo, R; Casaccia-Bonnefil, P; Osterhout, D J; Chao, M V
1998 Nov 7-12;24(1-2):283-283, Abstracts (Society for Neuroscience)
— id: 15931, year: 1998, vol: 24, page: 283, stat: Journal Article,

Clinical characterization and molecular basis for the apoptotic defect in humans with Fas mutations (Canale-Smith syndrome)
Vaishnaw, AK; Orlinick, JR; Ohsako, S; Chu, JL; Krammer, PH; Chao, MV; Elkon, KB
1998 SEP ;41(9):1511-1511, Arthritis & rheumatism
— id: 105087, year: 1998, vol: 41, page: 1511, stat: Journal Article,

Competitive signaling between TrkA and p75 nerve growth factor receptors determines cell survival
Yoon SO; Casaccia-Bonnefil P; Carter B; Chao MV
1998 May 1;18(9):3273-3281, Journal of neuroscience
In addition to its role as a survival factor, nerve growth factor (NGF) has been implicated in initiating apoptosis in restricted cell types both during development and after terminal cell differentiation. NGF binds to the TrkA tyrosine kinase and the p75 neurotrophin receptor, a member of the tumor necrosis factor cytokine family. To understand the mechanisms underlying survival versus death decisions, the TrkA receptor was introduced into oligodendrocyte cell cultures that undergo apoptosis in a p75-dependent manner. Here we report that activation of the TrkA NGF receptor in oligodendrocytes negates cell death by the p75 receptor. TrkA-mediated rescue from apoptosis correlated with mitogen-activated protein kinase activation. Concurrently, activation of TrkA in oligodendrocytes resulted in suppression of c-jun kinase activity initiated by p75, whereas induction of NFkappaB activity by p75 was unaffected. These results indicate that TrkA-mediated rescue involves not only activation of survival signals but also simultaneous suppression of a death signal by p75. The selective interplay between tyrosine kinase and cytokine receptors provides a novel mechanism that achieves alternative cellular responses by merging signals from different ligand-receptor systems
— id: 8296, year: 1998, vol: 18, page: 3273, stat: Journal Article,

Oligodendrocyte precursor differentiation is perturbed in the absence of the cyclin-dependent kinase inhibitor p27Kip1
Casaccia-Bonnefil P; Tikoo R; Kiyokawa H; Friedrich V Jr; Chao MV; Koff A
1997 Sep 15;11(18):2335-2346, Genes & development
During development of the central nervous system, oligodendrocyte progenitor cells (O-2A) undergo an orderly pattern of cell proliferation and differentiation, culminating in the ability of oligodendrocytes to myelinate axons. Here we report that p27(Kip1), a cyclin-dependent kinase inhibitor, is an important component of the decision of O-2A cells to withdraw from the cell cycle. In vitro, accumulation of p27 correlates with differentiation of oligodendrocytes. Furthermore, only a fraction of O-2A cells derived from p27-knockout mice differentiate successfully compared to controls. Inability to differentiate correlates with continued proliferation, suggesting that p27 is an important component of the machinery required for the G1/G0 transition in O-2A cells. In vivo, expansion of O-2A precursors before withdrawal, in part, leads to a greater number of oligodendrocytes. Together these data indicate a role for p27 during the decision to withdraw from the cell cycle in the oligodendrocyte lineage
— id: 14646, year: 1997, vol: 11, page: 2335, stat: Journal Article,

A novel interaction between the juxtamembrane region of the p55 tumor necrosis factor receptor and phosphatidylinositol-4-phosphate 5-kinase
Castellino AM; Parker GJ; Boronenkov IV; Anderson RA; Chao MV
1997 Feb 28;272(9):5861-5870, Journal of biological chemistry
Tumor necrosis factor-alpha (TNF-alpha) binding to its receptors leads to a diversity of biological responses. The actions of TNF are the result of the interaction of cytoplasmic proteins that bind directly to the intracellular domains of the two TNF receptors, p55 and p75. Here we report a novel interaction between the juxtamembrane region of the p55 TNF receptor and a newly discovered 47-kDa isoform of phosphatidylinositol-4-phosphate 5-kinase (PIP5K), a member of the enzyme family that generates the key signaling messenger, phosphatidylinositol 4,5-bisphosphate. The interaction was found to be specific for the p55 TNF receptor and was not observed with the p75 TNF receptor, the Fas antigen, or the p75 neurotrophin receptor, which are other members of the TNF receptor superfamily. In vitro experiments using recombinant fusion proteins verify the authenticity of the interaction between the p55 receptor and PIP5KIIbeta, a new isoform of PIP5K, but not the previously identified 53-kDa PIP5KIIalpha. Treatment of HeLa cells with TNF-alpha resulted in an increased PIP5K activity. These results indicate that phosphatidylinositol turnover may be linked to stimulation of the p55 TNF receptor and suggest that a subset of TNF responses may result from the direct association of PIP5KIIbeta with the p55 TNF receptor
— id: 14649, year: 1997, vol: 272, page: 5861, stat: Journal Article,

Entering the domain of neurotrophin binding [news]
Hempstead BL; Chao MV
1997 Jul;15(7):623-624, Nature biotechnology
— id: 14648, year: 1997, vol: 15, page: 623, stat: Journal Article,

Separate domains of the human fas ligand dictate self-association and receptor binding
Orlinick JR; Elkon KB; Chao MV
1997 Dec 19;272(51):32221-32229, Journal of biological chemistry
The Fas receptor rapidly induces apoptosis when activated by ligand binding or by cross-linking with anti-Fas antibody. The Fas ligand (FasL), a member of the tumor necrosis factor family of ligands, is a 40-kilodalton type II transmembrane protein which is cleaved to produce soluble ligand. Although the Fas-FasL interaction plays a critical role in peripheral T cell homeostasis and cytotoxic T lymphocyte-mediated target cell killing, the requirements for human FasL receptor binding and oligomerization have not been defined. Here we report two distinct domains of the ligand which are responsible for self-association and binding to the Fas receptor. A COOH-terminal sequence of the FasL was found to be required for binding and biological activity, as verified by deletion mutagenesis, use of the NOK-1 blocking antibody and the humanized gld FasL mutation. N-Linked glycosylation of the FasL was not required for biological activity. However, the FasL expression level was dependent upon the three N-linked glycosylation sites. Moreover, the ability of the FasL to self-associate was not dependent upon transmembrane or cytoplasmic sequences, but was localized to a 47-amino acid region in its extracellular domain. These results indicate that the FasL-Fas receptor complex depends upon independent motifs located within the extracellular domain of the FasL
— id: 14644, year: 1997, vol: 272, page: 32221, stat: Journal Article,

Requirement of cysteine-rich repeats of the Fas receptor for binding by the Fas ligand
Orlinick JR; Vaishnaw A; Elkon KB; Chao MV
1997 Nov 14;272(46):28889-28894, Journal of biological chemistry
The Fas receptor is a member of a family of cell death receptors, including tumor necrosis factor receptor I (TNFR I), death receptor 3 and 4 (DR3 and DR4), and cytopathic avian receptor 1 (CAR1). The Fas receptor is composed of several discrete domains, including three cysteine-rich domains (CRDs), a transmembrane domain, and an intracellular domain responsible for transmitting an apoptotic signal. While the mechanism of Fas-mediated cell death has become elucidated, the requirements for Fas ligand binding to the receptor have not been fully defined. Using a series of chimeric Fc-receptor fusion proteins between the human Fas receptor and TNFR I, each cysteine-rich domain of Fas was found to be required for interaction with the Fas ligand. Interestingly, TNFR I CRD1 could partially substitute for the Fas CRD1. The importance of this domain was underscored by the analysis of a Fas extracellular mutation (C66R), which resulted in a complete loss of ligand binding. This mutation was cloned from a human patient suffering from Canale-Smith syndrome, which is characterized by autoimmunity resembling that observed in the lpr and lprcg mice. The localization of essential ligand binding domains in the Fas receptor correlated exactly with the ability of the Fas receptor fusion proteins to prevent cell death mediated by the Fas ligand
— id: 14645, year: 1997, vol: 272, page: 28889, stat: Journal Article,

Changes in cyclin-dependent kinase 2 and p27kip1 accompany glial cell differentiation of central glia-4 cells
Tikoo R; Casaccia-Bonnefil P; Chao MV; Koff A
1997 Jan 3;272(1):442-447, Journal of biological chemistry
The generation of different glial cell types in the central nervous system depends upon a wide variety of proliferative and differentiative signals. Here we report that changes in the levels of cyclin-dependent kinase 2 (CDK2) and the cell cycle inhibitor p27kip1 accompany the differentiation of central glia-4 (CG-4) progenitor cells to an astrocytic cell phenotype in the presence of fetal calf serum. Although a decrease in CDK2 levels was observed in both oligodendrocyte and astrocyte cells derived from CG-4 cells, a striking increase in the levels of p27 was observed during the differentiation of astrocyte cells. In astrocyte cell extracts, inhibition of CDK2 activity could be overcome with exogenously added cyclin E. Furthermore, depletion of p27 from astrocyte extracts lowered the amount of cyclin E required for CDK2 activation. Taken together, these results suggest that the inhibitory action of p27 upon cyclin E-CDK2 may prevent entry of cells into the S phase and regulate the progression of CG-4 cells toward an astrocytic lineage
— id: 14650, year: 1997, vol: 272, page: 442, stat: Journal Article,

A dominant role of the juxtamembrane region of the TrkA nerve growth factor receptor during neuronal cell differentiation
Yoon SO; Soltoff SP; Chao MV
1997 Sep 12;272(37):23231-23238, Journal of biological chemistry
All receptor tyrosine kinases share a common intracellular signaling machinery, including ras activation, whereas cellular responses vary from mitogenesis to cell differentiation. To investigate the structural basis for receptor tyrosine kinase action for nerve growth factor, the juxtamembrane region of TrkA was transferred to a corresponding region of the epidermal growth factor (EGF) receptor. The resulting chimeric receptor contains an additional Shc site, Tyr490, in the juxtamembrane region. In transfected PC12 cell lines, neuronal differentiation was observed with EGF treatment, as evidenced by increased neurite extension. The action of the chimeric receptor was correlated with prolonged activation of MAP kinases and a 3-4-fold increase in phosphatidylinositol 3-kinase activity. The effect of the juxtamembrane chimera was dependent upon the Shc site at Tyr490, because expression of a chimeric receptor containing a Y490F mutation resulted in a complete loss of neuritogenesis by EGF treatment. These findings indicate that the juxtamembrane region of the TrkA receptor serves as a key functional domain that can confer a dominant effect upon neuronal differentiation
— id: 14647, year: 1997, vol: 272, page: 23231, stat: Journal Article,

Central glial and neuronal populations display differential sensitivity to ceramide-dependent cell death
Casaccia-Bonnefil P; Aibel L; Chao MV
1996 Feb 1;43(3):382-389, Journal of neuroscience research
Ceramide is a lipid second messenger implicated in the mechanism of apoptotic cell death. The effect of the cell-permeable ceramide analogue C2 has been tested on primary cortical cultures of neurons, astrocytes, and oligodendrocytes as well as on the bipotential glial precursor cell line CG-4. After 24 hr of treatment, C2 ceramide induced a dose-dependent cell death in primary oligodendrocytes and precursor cells, with a maximum effect at 10 microM. Commitment of oligodendrocytes to cell death occurred within the first 6 hr of treatment. Ultramicroscopic analysis of primary oligodendrocytes exposed to C2 ceramide for 3.5 hr revealed extensive membrane blebbing in the absence of nuclear condensation. In contrast, similar treatment of primary neuronal or astrocytic cortical cultures had no effect on cell survival. Neurons and astrocytes were resistant to 10 microM C2 ceramide. Furthermore, bipotential progenitors that were differentiated toward astrocytes also became resistant to ceramide treatment as they acquired a mature astrocytic phenotype. These experiments suggest that cell type specific factors are required for ceramide-mediated cell death in the nervous system
— id: 14655, year: 1996, vol: 43, page: 382, stat: Journal Article,

Death of oligodendrocytes mediated by the interaction of nerve growth factor with its receptor p75
Casaccia-Bonnefil P; Carter BD; Dobrowsky RT; Chao MV
1996 Oct 24;383(6602):716-719, Nature
Members of the nerve growth factor (NGF) family promote the survival of neurons during development. NGF specifically activates the receptor trkA, initiating a signal transduction cascade which ultimately blocks cell death. Here we show that NGF can have the opposite effect, inducing the death of mature oligodendrocytes cultured from postnatal rat cerebral cortex. This effect was highly specific, because NGF had no effect on oligodendrocyte precursors and astrocytes. Other neurotrophins such as brain-derived neurotrophin factor (BDNF) and neurotrophin-3 (NT-3) did not induce cell death. NGF binding to mature oligodendrocytes expressing the p75 neurotrophin receptor, but not trkA, resulted in a sustained increase of intracellular ceramide and c-Jun amino-terminal kinase (JNK) activity, which are thought to participate in a signal transduction pathway leading to cell death. Taken together, these results indicate that NGF has the ability to promote cell death in specific cell types through a ligand-dependent signalling mechanism involving the p75 neurotrophin receptor
— id: 14651, year: 1996, vol: 383, page: 716, stat: Journal Article,

Trans-signaling by cytokine and growth factor receptors
Castellino AM; Chao MV
1996 Dec;7(4):297-302, Cytokine & growth factor reviews
Although ligand-induced dimerization or oligomerization of receptors is a well established mechanism of growth factor signaling, increasing evidence indicates that biological responses are often mediated by receptor trans-signaling mechanisms involving two or more receptor systems. These include G protein-coupled receptors, cytokine, growth factor and trophic factor receptors. Greater responsiveness and inhibitory signaling responses are provided when different signaling pathways merge through receptor trans-signaling
— id: 57464, year: 1996, vol: 7, page: 297, stat: Journal Article,

Interactions of cellular polypeptides with the cytoplasmic domain of the mouse Fas antigen
Orlinick JR; Chao MV
1996 Apr 12;271(15):8627-8632, Journal of biological chemistry
The mouse Fas/APO-1 antigen represents a 45-kilodalton transmembrane receptor that initiates apoptosis by a poorly defined signaling mechanism. The cytoplasmic domain of Fas does not display any known enzymatic activities but is capable of interacting with a number of proteins that were identified recently using the yeast interactive cloning method. To investigate direct biochemical interactions from cellular lysates prepared from Fas-responsive cells, a series of recombinant glutathione S-transferase-mouse Fas fusion proteins representing different regions of the mouse Fas cytoplasmic domain was used. Polypeptides of 25, 50, and 70 kilodaltons were found to associate with the Fas intracellular domain, and this binding was stable in the presence of 1 M NaCl. These interactions were also detected using a mouse Fas fusion protein containing an Ile to Asn mutation, which is responsible for a lymphoproliferative disorder in certain strains of mice (lprcg). Furthermore, the binding of cellular proteins to Fas could be blocked upon incubation with a polyclonal antibody directed against the cytoplasmic domain of Fas. The strong association of cellular proteins with the cytoplasmic region implies that constitutive interactions may exist to regulate apoptotic signaling through the Fas antigen
— id: 14654, year: 1996, vol: 271, page: 8627, stat: Journal Article,

Mutation and expression of the low affinity neurotrophin receptor in human malignant melanoma
Papandreou C; Bogenrieder T; Loganzo F; Chao MV; Nanus DM; Albino AP
1996 Oct;6(5):373-378, Melanoma research
The low affinity p75 neurotrophin receptor (p75NTR) is a cysteine-rich transmembrane glycoprotein which is frequently overexpressed in advanced stages of human melanoma. The biological consequences of this overexpression are unknown; however, it has recently been shown that p75NTR can enhance the invasive potential of melanoma cells in vitro. In the present study we examined cell lines established from normal human melanocytes and metastatic melanomas for expression of p75NTR mRNA and protein. The results showed that, compared with normal melanocytes, levels of p75NTR-specific protein were high in seven melanoma lines, markedly decreased in two melanoma lines and comparable in two melanoma lines. The conserved transmembrane domain of p75NTR was analysed for point mutations by single strand conformation polymorphism analysis and direct DNA sequencing. Identical point mutations were detected in the transmembrane domain of p75NTR in the two melanoma lines with reduced p75NTR protein expression, which resulted in the substitution of the uncharged amino acid Gly for the negatively-charged Asp
— id: 14653, year: 1996, vol: 6, page: 373, stat: Journal Article,

Adenovirus-mediated gene delivery into neuronal precursors of the adult mouse brain
Yoon SO; Lois C; Alvirez M; Alvarez-Buylla A; Falck-Pedersen E; Chao MV
1996 Oct 15;93(21):11974-11979, Proceedings of the National Academy of Sciences of the United States of America
Precursor cells found in the subventricular zone (SVZ) of the adult brain can undergo cell division and migrate long distances before differentiating into mature neurons. We have investigated the possibility of introducing genes stably into this population of cells. Replication-defective adenoviruses were injected into the SVZ of the lateral ventricle of adult mice. The adenoviruses carried a cDNA for the LacZ reporter or the human p75 neurotrophin receptor, for which species-specific antibodies are available. Injection of the viruses into the SVZ led to efficient labeling of neuronal precursors. Two months after viral injection, infected cells were detected in the olfactory bulb, a significant distance from the site of injection. Labeled periglomerular and granular neurons with extensive dendritic arborization were found in the olfactory bulb. These results demonstrate that foreign genes can be efficiently introduced into neuronal precursor cells. Furthermore, adenovirus-directed infection can lead to long-term stable gene expression in progenitor cells found in the adult central nervous system
— id: 14652, year: 1996, vol: 93, page: 11974, stat: Journal Article,

Ceramide: a potential second messenger in the nervous system
Chao MV
1995 Apr;6(2):91-96, Molecular & cellular neurosciences
— id: 14662, year: 1995, vol: 6, page: 91, stat: Journal Article,

p75 and Trk: a two-receptor system
Chao MV; Hempstead BL
1995 Jul;18(7):321-326, Trends in neurosciences
The neurotrophin family of survival factors is distinguished by a unique receptor-signaling system that is composed of two transmembrane receptor proteins. Nerve growth factor (NGF), brain-derived neurotrophic factor, neurotrophin-3 (NT-3) and NT-4/5 share similar protein structures and biological functions and interact with two different types of cell-surface proteins, the Trk family of receptor tyrosine kinases, and the p75, or low-affinity neurotrophin receptor. An important question is whether a dual receptor system is necessary for neurotrophin action. Evidence indicates that co-expression of the two genes for the p75 receptor and the Trk NGF receptor can potentially lead to greater responsiveness to NGF, and suggests additional levels of regulation for the family of neurotrophin factors
— id: 14658, year: 1995, vol: 18, page: 321, stat: Journal Article,

Differential role of the low affinity neurotrophin receptor (p75) in retrograde axonal transport of the neurotrophins
Curtis R; Adryan KM; Stark JL; Park JS; Compton DL; Weskamp G; Huber LJ; Chao MV; Jaenisch R; Lee KF; et al
1995 Jun;14(6):1201-1211, Neuron
The receptor mechanisms mediating the retrograde axonal transport of the neurotrophins have been investigated in adult rats. We show that transport of the TrkB ligands NT-4 and BDNF to peripheral neurons is dependent on the low affinity neurotrophin receptor (LNR). Pharmacological manipulation of LNR in vivo using either an anti-LNR antibody or a soluble recombinant LNR extracellular domain completely blocked retrograde transport of NT-4 and BDNF to sensory neurons, while having minimal effects on the transport of NGF in either sensory or sympathetic neurons. Furthermore, in mice with a null mutation of LNR, the transport of NT-4 and BDNF, but not NGF, was dramatically reduced. These observations demonstrate a selective role for LNR in retrograde transport of the various neurotrophins from distinct target regions in vivo
— id: 14660, year: 1995, vol: 14, page: 1201, stat: Journal Article,

Regulation of Id1 and its association with basic helix-loop-helix proteins during nerve growth factor-induced differentiation of PC12 cells
Einarson MB; Chao MV
1995 Aug;15(8):4175-4183, Molecular & cellular biology
Cell differentiation in the nervous system is dictated by specific patterns of gene expression. We have investigated the role of helix-loop-helix (HLH) proteins during differentiation of PC12 pheochromocytoma cells in response to nerve growth factor. Gel mobility shift assays using PC12 cell nuclear extracts demonstrated that active basic HLH complexes exist throughout differentiation. Addition of exogeneous Id1 protein, a negative regulator of basic HLH proteins, disrupted specific complexes formed by PC12 cell nuclear extracts on a CANNTG consensus oligonucleotide. To identify possible novel basic HLH proteins in these complexes, a glutathione S-transferase-Id1 fusion protein was used to screen a PC12 cell cDNA expression library. A single clone representing the rat E2-2 gene was identified. Sequential immunoprecipitations with antibodies to each HLH protein revealed an association between Id1 and E2-2 that could be detected in both untreated and nerve growth factor-treated PC12 cell lysates. These experiments define a new HLH interaction between Id1 and E2-2 in neuronal cells and suggest that neuronal differentiation may be regulated by HLH proteins in a distinctive manner
— id: 14657, year: 1995, vol: 15, page: 4175, stat: Journal Article,

A potential interaction of p75 and trkA NGF receptors revealed by affinity crosslinking and immunoprecipitation
Huber LJ; Chao MV
1995 Mar 1;40(4):557-563, Journal of neuroscience research
Nerve growth factor binds independently to two transmembrane receptors, the p75 neurotrophin receptor and the p140trk (trkA) tyrosine kinase receptor, which are both co-expressed in the majority of neuronal cells that respond to NGF. Previous findings have suggested that appropriate co-expression of the two receptors gives rise to high affinity NGF binding sites and increased neurotrophin responsiveness; however, evidence demonstrating a direct interaction between the two receptors in cell lines has been lacking. Here we have utilized affinity crosslinking agents with 125I-NGF to detect an association of trkA and p75 receptors in embryonic spinal cord and brain tissues enriched in the two receptors. Although multimeric complexes of trkA and p75 were not detected by affinity crosslinking, immunoprecipitation of cross-linked NGF-receptor complexes with trk-specific antibodies resulted in selective immunoprecipitation of crosslinked p75. Our results indicate that the trkA and p75 receptors can potentially interact, and that such an association may be responsible for the generation of high affinity NGF binding sites
— id: 14663, year: 1995, vol: 40, page: 557, stat: Journal Article,

Mesenchymal and neuronal cell expression of the p75 neurotrophin receptor gene occur by different mechanisms
Huber LJ; Chao MV
1995 Jan;167(1):227-238, Developmental biology (Orlando)
The p75 neurotrophin receptor serves as a receptor for all known neurotrophins, including NGF, BDNF, NT-3, and NT-4/5. The expression pattern of p75 is known to be widespread and extends outside the nervous system, suggesting that neurotrophins may have functions beyond neuronal cell survival and differentiation. To investigate the expression of p75, a human minigene was constructed that contained the full-length receptor cDNA directed by its own promoter and 4 kb of 5' upstream sequence. This minigene was used to generate transgenic mice and was found to be expressed in selective neuronal populations such as the cerebellar external granular layer. Expression of the transgene was not observed in sensory or sympathetic ganglia or in the basal forebrain. Transection of the sciatic nerve revealed that the human transgene was appropriately upregulated after nerve injury, indicating that sequences responsible for proper induction during nerve regeneration reside in the minigene construct. In contrast, the p75 transgene was found to be extensively expressed in mesenchymal cells during development, closely mimicking the in vivo pattern of expression. The detection of p75 receptors in the mesenchyme implies that neurotrophins are likely to exert effects during morphogenesis of mesodermal tissues and that separate signals are likely to direct neuronal versus nonneuronal expression of the p75 gene
— id: 14665, year: 1995, vol: 167, page: 227, stat: Journal Article,

Structural determinants of neurotrophin action
McDonald NQ; Chao MV
1995 Aug 25;270(34):19669-19672, Journal of biological chemistry
Five decades of research on NGF have led to the discovery of a small family of evolutionarily conserved proteins, which have vital functions in the survival and neuronal development of specific neuronal populations. The generation of mice lacking neurotrophin expression has recapitulated classic experiments using anti-NGF antibodies to dissect the physiological effects of trophic factor deprivation (73). Very similar outcomes resulted from both the NGF immunodepletion experiments and the transgenic mouse experiments. The genetic results also verify the structural predictions made from binding results in heterologous cells. The findings in cell culture and animal experiments clearly indicate the efficacy of neurotrophic factors for promoting the survival of prominent neuronal populations such as sensory and motor neurons. The high degree of conservation of neurotrophin structure is accompanied by a surprising variation in the amino acid contacts used by each neurotrophin with p75 and the trk receptor family members. It is this variation that may provide specificity for each ligand-receptor complex. The future challenge will be to make use of this knowledge to design effective therapeutic strategies to treat neurodegeneration and nerve injury
— id: 14656, year: 1995, vol: 270, page: 19669, stat: Journal Article,

Expression of trk receptors in the developing and adult human central and peripheral nervous system
Muragaki Y; Timothy N; Leight S; Hempstead BL; Chao MV; Trojanowski JQ; Lee VM
1995 Jun 5;356(3):387-397, Journal of comparative neurology
A family of tyrosine receptor kinases known collectively as trk receptors plays an essential role in signal transduction mediated by nerve growth factor and related neurotrophins. To localize the major trk receptors (trkA, B and C) in the developing and adult central (CNS) and peripheral (PNS) nervous system, we generated monoclonal antibodies (MAbs) to extracellular (MAbs E7, E13, E16, E21, E29) and intracellular (MAb I2) domains of human trkA fused to glutathione S-transferase. Several MAbs (E7, E13, E16) recognized glycosylated trkA (gp140trk and gp110trk) in Western blots, one MAb (E7) recognized non-glycosylated (p80trk) and glycosylated trkA in immunoprecipitation assays, and two MAbs (E13, E29) detected trkA on the cell surface of NIH3T3 cells transfected with a trkA cDNA. Although generated to trkA fusion proteins, this panel of MAbs also recognized trkB and trkC in flow cytometric studies of NIH3T3 cells transfected with trkB or trkC cDNAs. Thus, we used these pan-trk MAbs to probe selected regions of the CNS and PNS including the hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and dorsal root ganglion (DRG) to localize trkA, B, and C receptors in the developing and adult human nervous system. These studies showed that trk receptors are expressed primarily by neurons and are detectable very early in the developing hippocampus, cerebellum, spinal cord, and DRG. Although the distribution and intensity of trk immunoreactivity changed with the progressive maturation of the CNS and PNS, immunoreactive trk receptors were detected in neurons of the adult human hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and DRG. This first study of trk receptor proteins in the developing and adult human CNS and PNS documents the expression of these receptors in subsets of neurons throughout the developing and adult nervous system. Thus, although the expression of trk receptor proteins is developmentally regulated, the constitutive expression of these neurotrophin receptors by neurons in many regions of the adult human CNS and PNS implies that mature trk receptor-bearing neurons retain the ability to respond to neurotrophins long after terminal neuronal differentiation is complete
— id: 14659, year: 1995, vol: 356, page: 387, stat: Journal Article,

NGF binding to the trk tyrosine kinase receptor requires the extracellular immunoglobulin-like domains
Perez P; Coll PM; Hempstead BL; Martin-Zanca D; Chao MV
1995 Apr;6(2):97-105, Molecular & cellular neurosciences
Neurotrophins initiate their biological effects by activating members of the trk tyrosine kinase subfamily. The extracellular region of trk receptors is distinguished by several common structural features, including leucine-rich repeats, clusters of cysteine-rich domains, and two immunoglobulin-like domains. However, the receptor sequences required for ligand binding have not been localized. In order to define the domains involved in NGF binding, a series of chimeric receptors was constructed using cDNA sequences from rat trkA and trkB. The chimeric constructs were expressed after transient transfection in 293 cells and the expression of each receptor was verified by immunoprecipitation and immunoblot analysis. Equilibrium binding of transfected cells revealed that the two IgG domains of trkA are essential for NGF binding. The requirement for the two IgG domains was further confirmed by Scatchard analysis and affinity crosslinking with 125I-NGF. These results indicate that NGF binding is crucially dependent upon interactions with the IgG domains of the trkA receptor
— id: 14661, year: 1995, vol: 6, page: 97, stat: Journal Article,

Upregulation of NF-kappa B-dependent gene expression mediated by the p75 tumor necrosis factor receptor
Rao P; Hsu KC; Chao MV
1995 Feb;15(2):171-177, Journal of interferon & cytokine research
Tumor necrosis factor (TNF-alpha) interacts with two transmembrane receptor proteins, p55TNFR and p75TNFR, which are members of a family of cell surface molecules that include the Fas antigen, CD27, CD30, CD40, OX40, a Shope fibroma viral protein, and the low-affinity p75 neurotrophin receptor. Although the p55 TNF receptor has been shown to be primarily responsible for the biologic responses of TNF-alpha, the exact involvement of the p75 TNF receptor in signaling events is unclear. Here we show that expression of a human cDNA clone for p75 in COS-1 and 3T3 cells results in the constitutive activation of an TNF-inducible NF-kappa B-containing promoter. Analysis of a number of chimeric p75 receptor cDNA constructs further suggests that this activity requires the cytoplasmic domain of the p75 receptor. These results therefore indicate that the p75 TNF receptor is capable of mediating signal transduction
— id: 14664, year: 1995, vol: 15, page: 171, stat: Journal Article,

The p75 neurotrophin receptor
Chao MV
1994 Nov;25(11):1373-1385, Journal of neurobiology
The low-affinity p75 molecule and trk tyrosine kinases serve as receptors for target-derived neurotrophins. While the mechanism by which receptor tyrosine kinases impart intracellular signaling has become well understood, the precise roles of the p75 receptor are not fully defined. The p75 neurotrophin receptor belongs to a family of transmembrane molecules which also serve as receptors for the tumor necrosis factor family of cytokines. Each receptor shares a common extracellular structure highlighted by conserved cysteine-rich repeats. Because NGF, BDNF, NT-3, and NT-4/5 bind to p75 with similar affinity, p75 may either act as a common subunit in a neurotrophin receptor complex with trk family members, or act by independent mechanisms to mediate biological actions of each neurotrophin
— id: 14666, year: 1994, vol: 25, page: 1373, stat: Journal Article,

MOLECULAR MECHANISMS OF ACTION BY NGF RECEPTORS
CHAO, MV
1994 SEP 9 ;63(5178):S15-S15, Journal of neurochemistry
— id: 105089, year: 1994, vol: 63, page: S15, stat: Journal Article,

Activation of the sphingomyelin cycle through the low-affinity neurotrophin receptor
Dobrowsky RT; Werner MH; Castellino AM; Chao MV; Hannun YA
1994 Sep 9;265(5178):1596-1599, Science
The role of the low-affinity neurotrophin receptor (p75NTR) in signal transduction is undefined. Nerve growth factor can activate the sphingomyelin cycle, generating the putative-lipid second messenger ceramide. In T9 glioma cells, addition of a cell-permeable ceramide analog mimicked the effects of nerve growth factor on cell growth inhibition and process formation. This signaling pathway appears to be mediated by p75NTR in T9 cells and NIH 3T3 cells overexpressing p75NTR. Expression of an epidermal growth factor receptor-p75NTR chimera in T9 cells imparted to epidermal growth factor the ability to activate the sphingomyelin cycle. These data demonstrate that p75NTR is capable of signaling independently of the trk neurotrophin receptor (p140trk) and that ceramide may be a mediator in neurotrophin biology
— id: 14667, year: 1994, vol: 265, page: 1596, stat: Journal Article,

NERVE GROWTH-FACTOR (NGF) ACTIVATES THE SPHINGOMYELIN CYCLE - IDENTIFICATION OF A SIGNAL-TRANSDUCTION PATHWAY FOR THE LOW-AFFINITY NGF RECEPTOR
DOBROWSKY, RT; CASTELLINO, A; CHAO, MV; HANNUN, YA
1994 SEP 9 ;63(5178):56-56, Journal of cellular biochemistry
— id: 105090, year: 1994, vol: 63, page: 56, stat: Journal Article,

NERVE GROWTH-FACTOR (NGF) ACTIVATES THE SPHINGOMYELIN CYCLE - IDENTIFICATION OF A SIGNAL-TRANSDUCTION PATHWAY FOR THE LOW-AFFINITY NGF RECEPTOR
DOBROWSKY, RT; CASTELLINO, A; CHAO, MV; HANNUN, YA
1994 APR 19 ;8(7):A1341-A1341, FASEB journal
— id: 105091, year: 1994, vol: 8, page: A1341, stat: Journal Article,

High affinity nerve growth factor binding displays a faster rate of association than p140trk binding. Implications for multi-subunit polypeptide receptors
Mahadeo D; Kaplan L; Chao MV; Hempstead BL
1994 Mar 4;269(9):6884-6891, Journal of biological chemistry
Nerve growth factor (NGF) binds to two cell surface receptors, p140trk and p75NGFR, which are both expressed in responsive sensory, sympathetic, and basal forebrain cholinergic neurons. While p140trk belongs to the family of receptor tyrosine kinases, p75NGFR is a member of the TNF/Fas/CD40/CD30 family of receptors. Current views of neurotrophin receptor function have tended to interpret p140trk as the high affinity NGF-binding site. To assess if the binding of NGF to p140trk was distinguishable from binding to high affinity sites on neuronal cells, PC12 cell sublines were generated which expressed p140trk alone, or coexpressed both p140trk and p75NGFR. Kinetic analysis of 125I-NGF binding indicates that it has an unusually slow rate of association with p140trk (k + 1 = 8 x 10(5) M-1 s-1). When both p140trk and p75NGFR receptors are coexpressed, the rate of association of NGF is increased 25-fold to produce a higher affinity binding site. An increase in the rate of internalization was also observed. Since high affinity binding and internalization are believed to be prerequisite for the biological activities of NGF, these results suggest that the biological effects by NGF are derived from a novel kinetic binding site that requires the expression of both receptors. The implications of these results with respect to multisubunit polypeptide receptors are discussed
— id: 14669, year: 1994, vol: 269, page: 6884, stat: Journal Article,

Nerve growth factor production by lymphocytes
Santambrogio L; Benedetti M; Chao MV; Muzaffar R; Kulig K; Gabellini N; Hochwald G
1994 Nov 15;153(10):4488-4495, Journal of immunology
Nerve growth factor (NGF) is a neurotrophic protein essential for the maintenance and growth of peripheral sympathetic neurons and basal forebrain cholinergic neurons. Recently, NGF has also been shown to have effects on cells of the immune system. In a search for extra neural sources of NGF, we detected NGF-specific mRNA in mouse T lymphocytes of both the CD4+ and CD8+ phenotypes with the use of an RNase protection assay, PCR, and DNA sequence analysis. In CD4+ cells, NGF was present in both Th1 and Th2 Ag-specific clones, but an increase of NGF-specific message was detected after antigenic stimulation only in Th2 clones. NGF mRNA was also detected in splenic B lymphocytes and in a cell line derived from a murine follicular center cell lymphoma. Translation into protein and secretion of NGF were demonstrated by Western blot analysis. The secreted NGF is in an active form capable of inducing differentiation of PC12 cells into sympathetic-like neurons. Furthermore, conditioned medium from clones or lines positive for NGF mRNA was capable of inducing p140 tyrosine kinase autophosphorylation in 3T3 fibroblasts transfected with cDNA encoding for the tyrosine kinase family NGF receptor. We conclude that lymphocytes synthesize and secrete NGF either as a para-autocrine factor acting on the immune system itself, or as a factor for the maintenance of peripheral neurons
— id: 8246, year: 1994, vol: 153, page: 4488, stat: Journal Article,

p75LNGFR regulates Trk signal transduction and NGF-induced neuronal differentiation in MAH cells
Verdi JM; Birren SJ; Ibanez CF; Persson H; Kaplan DR; Benedetti M; Chao MV; Anderson DJ
1994 Apr;12(4):733-745, Neuron
We have examined NGF-induced signal transduction events and neuronal differentiation in MAH cells, a neuronal progenitor cell line, in which the expression of the two NGF receptors, p140trk (Trk) and p75LNGFR (p75), has been independently manipulated. Coexpression of a large molar excess of p75 substantially enhances the NGF-induced tyrosine autophosphorylation of Trk, compared with cells expressing Trk alone. MAH cells expressing both Trk and p75 stop dividing and acquire a mature neuronal morphology more rapidly and with greater efficiency than MAH cells expressing Trk alone. These biochemical and biological influences of p75 are not observed using a mutant form of NGF that binds Trk but not p75. These data provide evidence that p75 can modulate signal transduction through Trk in a neuronal progenitor cell context and that such modulation has functional consequences for the neuronal differentiation pathway induced by NGF
— id: 14668, year: 1994, vol: 12, page: 733, stat: Journal Article,

A ROLE FOR P75 NERVE GROWTH-FACTOR RECEPTOR IN PROGRAMMED MELANOCYTE CELL-DEATH AFTER INJURY AND WITH AGING
ZHAI, S; YAAR, M; CHAO, MV; REENSTRA, WR; GILCHREST, BA
1994 APR ;102(4):545-545, Journal of investigative dermatology
— id: 105088, year: 1994, vol: 102, page: 545, stat: Journal Article,

HSV-1 vector-mediated gene transfer of the human nerve growth factor receptor p75hNGFR defines high-affinity NGF binding
Battleman DS; Geller AI; Chao MV
1993 Mar;13(3):941-951, Journal of neuroscience
A series of recombinant herpes simplex virus (HSV-1) vectors have been constructed that encode either the full-length cDNA of the human p75 NGF receptor (p75hNGFR) or truncated forms of the receptor. Infection of cultured fibroblast cells with viral stocks results in abundant expression of all three cDNAs, as detected by affinity cross-linking, immunoblot analysis, and equilibrium binding. Furthermore, viral infection of primary neuronal cultures gives easily detectable p75 expression by immunofluorescence and affinity cross-linking. When p75 was introduced by viral infection into fibroblast cells expressing the trk proto-oncogene, a new binding site was created, consistent with high-affinity NGF binding. This site is not created by the coexpression of truncated forms of p75 that lack either the extracellular ligand binding domain or the cytoplasmic domain of the receptor, suggesting that both of these regions of the receptor are required for the formation of the high-affinity NGF binding site. Hence, these HSV-1 vectors give rise to appropriate NGF receptor binding after viral infection. The application of these HSV-1 constructs to primary neuronal culture and in vivo models of p75NGFR function is discussed
— id: 14673, year: 1993, vol: 13, page: 941, stat: Journal Article,

Differential expression of nerve growth factor receptors leads to altered binding affinity and neurotrophin responsiveness
Benedetti M; Levi A; Chao MV
1993 Aug 15;90(16):7859-7863, Proceedings of the National Academy of Sciences of the United States of America
The low-affinity p75 neurotrophin receptor is believed to participate with the Trk receptor tyrosine kinase in the formation of high-affinity binding sites for nerve growth factor (NGF). To investigate the functional significance of the two NGF receptors, a truncated p75 receptor was stably expressed in PC12 rat pheochromocytoma cells, yielding cells with greatly reduced levels of wild-type p75 and normal Trk levels. Although these cells were capable of normal differentiation by NGF, very few high-affinity NGF binding sites were detected. These findings indicate that high-affinity binding may be functionally dissociated from biological responses. Furthermore, an increased responsiveness to neurotrophin 3 was observed, as manifested by increased neurite outgrowth. These results suggest that a correct ratio of p75 and p140trk is required to create high-affinity sites and that p75 expression may assist in the discrimination between related but different neurotrophin factors
— id: 14671, year: 1993, vol: 90, page: 7859, stat: Journal Article,

DISTINCTIVE FUNCTIONS OF NGF RECEPTORS
CHAO, MV; HUBER, J; BENEDETTI, M; HEMPSTEAD, B
1993 AUG 5 ;61(22):S119-S119, Journal of neurochemistry
— id: 105092, year: 1993, vol: 61, page: S119, stat: Journal Article,

Immunohistochemical localization of Trk receptor protein in pediatric small round blue cell tumors
Donovan MJ; Hempstead BL; Horvath C; Chao MV; Schofield D
1993 Dec;143(6):1560-1567, American journal of pathology
Expression of Trk protein has been documented by Northern analysis in neuroblastomas with good prognosis. To localize the expression of this protein at the cellular level within individual tumors, we adapted a recently characterized pan-Trk antibody for use in formalin fixed, paraffin-embedded tissue. We have examined a group of small round blue cell tumors occurring in children, including both high and low stage neuroblastomas, to assess the presence or absence of Trk expression and its cellular localization. Positive staining for Trk protein was observed in four of four low stage (good prognosis) neuroblastomas, five of five primitive neuroectodermal tumors/Ewing's sarcoma, five of five rhabdomyosarcomas, and no lymphomas. Within the neuroblastomas, expression of Trk protein was most striking in ganglion cells, in which positive cytoplasmic staining was demonstrated regardless of tumor stage. The latter observation may lend further insight into the pathobiology of this malignant childhood tumor
— id: 14670, year: 1993, vol: 143, page: 1560, stat: Journal Article,

Analysis of the trk NGF receptor tyrosine kinase using recombinant fusion proteins
Horvath CM; Wolven A; Machadeo D; Huber J; Boter L; Benedetti M; Hempstead B; Chao MV
1993 ;17:223-228, Journal of cell science. Supplement
Nerve growth factor (NGF) represents a family of structurally related trophic factors, including brain-derived neurotrophin factor (BDNF), neurotrophin-3 (NT-3), NT-4, and NT-5. These neurotrophin factors interact with two classes of receptors, the trk receptor tyrosine kinase family, and the low affinity p75 neurotrophin receptor. To study potential ligand-receptor interactions, recombinant trk fusion proteins have been constructed, and pan-trk polyclonal antisera directed against the cytoplasmic tyrosine kinase domain have been generated. The recombinant proteins were assessed for in vitro kinase activity and for the ability of K-252a to inhibit phosphorylation. Antibodies made against the fusion protein recognize all trk family members, and are effective in immunoprecipitation of affinity-crosslinked receptors. Comparative crosslinking indicates that NGF can recognize all trk receptor members, illustrating the large number of potential ligand-receptor interactions between neurotrophins and their receptors
— id: 14674, year: 1993, vol: 17, page: 223, stat: Journal Article,

Differential expression and ligand binding properties of tumor necrosis factor receptor chimeric mutants
Hsu KC; Chao MV
1993 Aug 5;268(22):16430-16436, Journal of biological chemistry
The receptors for tumor necrosis factor (TNF) are represented by two transmembrane proteins, p55TNFR and p75TNFR, which are members of a family of cell surface molecules, including the Fas antigen, CD30, CD40, OX40, a Shope fibroma virus protein, and the low affinity p75 nerve growth factor receptor. A common structural feature is a sequence of 40 amino acids that is found in adjacent repeated domains, with 6 cysteine residues in a conserved register. To assess the functional significance of this cysteine-rich domain (CRD), we have constructed chimeric receptors between each TNF receptor and the low affinity nerve growth factor receptor. The chimeric receptor cDNAs were expressed efficiently in COS-1 and 3T3 fibroblasts, as assessed by affinity cross-linking, cell surface biotinylation and immunoprecipitation, and equilibrium binding. Receptors with two CRD of either TNF receptor were incapable of binding TNF, whereas receptors with all four CRD retained the ability to bind TNF with wild type affinity. These results, in conjunction with previous deletion mutation studies, suggest that TNF binding to each receptor requires all four cysteine-rich repeats. Furthermore, analysis of chimeric receptors containing domains of p55TNFR suggests that cytoplasmic sequences directly influence the levels of receptor expression
— id: 14672, year: 1993, vol: 268, page: 16430, stat: Journal Article,

K-252a inhibits nerve growth factor-induced trk proto-oncogene tyrosine phosphorylation and kinase activity
Berg MM; Sternberg DW; Parada LF; Chao MV
1992 Jan 5;267(1):13-16, Journal of biological chemistry
The rat pheochromocytoma PC12 cell line differentiates into a sympathetic neuronal phenotype upon treatment with either nerve growth factor (NGF) or basic fibroblast growth factor. The alkaloid-like compound K-252a has been demonstrated to be a specific inhibitor of NGF-induced biological responses in PC12 cells (Koizumi, S., Contreras, M. L., Matsuda, Y., Hama, T., Lazarovici, P., and Guroff, G. (1988) J. Neurosci. Res. 8, 715-721). NGF interacts with the protein product of the proto-oncogene trk and rapidly stimulates the tyrosine phosphorylation of both p140prototrk and a number of cellular substrates. Here we show that these phosphorylation events are directly inhibited in PC12 cells by K252a in a dose-dependent manner, indicating that the site of action of this inhibitor is at the NGF receptor level. K-252a inhibits p140prototrk activity in vitro, demonstrating that K-252a has a direct effect on the p140prototrk tyrosine kinase. Though many of the biochemical responses to NGF in PC12 cells are mimicked by basic fibroblast growth factor and epidermal growth factor, K-252a has no effect on the action of these growth factors in PC12 cells, demonstrating that the initial biological events initiated by NGF are distinctive during neuronal differentiation
— id: 14678, year: 1992, vol: 267, page: 13, stat: Journal Article,

Growth factor signaling: where is the specificity?
Chao MV
1992 Mar 20;68(6):995-997, Cell
— id: 14677, year: 1992, vol: 68, page: 995, stat: Journal Article,

Neurotrophin receptors: a window into neuronal differentiation
Chao MV
1992 Oct;9(4):583-593, Neuron
— id: 14675, year: 1992, vol: 9, page: 583, stat: Journal Article,

Receptors for nerve growth factor
Chao MV; Battleman DS; Benedetti M
1992 ;137B:169-180, International review of cytology
— id: 14679, year: 1992, vol: 137B, page: 169, stat: Journal Article,

KINETIC-ANALYSIS OF NERVE GROWTH-FACTOR BINDING TO ITS CELL-SURFACE RECEPTORS
CHAO, MV; KAPLAN, LK; HEMPSTEAD, BL
1992 APR ;40(2):A331-A331, Clinical research
— id: 105093, year: 1992, vol: 40, page: A331, stat: Journal Article,

Targeted mutation of the gene encoding the low affinity NGF receptor p75 leads to deficits in the peripheral sensory nervous system
Lee KF; Li E; Huber LJ; Landis SC; Sharpe AH; Chao MV; Jaenisch R
1992 May 29;69(5):737-749, Cell
We have generated mice carrying a mutation of the gene encoding the low affinity NGF receptor p75NGFR by targeted mutation in embryonic stem cells. Mice homozygous for the mutation were viable and fertile. Immunohistochemical analyses of the footpad skin of mutant mice revealed markedly decreased sensory innervation by calcitonin gene-related peptide- and substance P-immunoreactive fibers. The defective innervation was correlated with loss of heat sensitivity and associated with the development of ulcers in the distal extremities. Complicated by secondary bacterial infection, the ulcers progressed to toenail and hair loss. Crossing a human transgene encoding p75NGFR into the mutant animals rescued the absent heat sensitivity and the occurrence of skin ulcers and increased the density of neuropeptide-immunoreactive sensory innervation of footpad skin. The mutation in the gene encoding p75NGFR did not decrease the size of sympathetic ganglia or the density of sympathetic innervation of the iris or salivary gland. Our results suggest that p75NGFR has an important role in the development and function of sensory neurons
— id: 14676, year: 1992, vol: 69, page: 737, stat: Journal Article,

The low-affinity p75 nerve growth factor (NGF) receptor mediates NGF-induced tyrosine phosphorylation
Berg MM; Sternberg DW; Hempstead BL; Chao MV
1991 Aug 15;88(16):7106-7110, Proceedings of the National Academy of Sciences of the United States of America
Protein tyrosine phosphorylation is a potential mechanism for initial signaling in PC12 cells during differentiation in response to nerve growth factor (NGF). NGF-induced tyrosine phosphorylation has been found to be initiated by the trk protooncogene, which participates in the formation of high-affinity NGF binding sites. In contrast to transfection of wild-type low-affinity p75 NGF receptors, transfection of p75NGFR with mutations in the cytoplasmic domain resulted in an inability of NGF to elicit tyrosine phosphorylation of intracellular substrates, indicating that p75NGFR is involved in initiating phosphorylation events by NGF. Even though the p75NGFR receptor does not possess any inherent tyrosine kinase activity, these experiments demonstrate that the p75NGFR has a potential role in NGF-induced tyrosine phosphorylation
— id: 14682, year: 1991, vol: 88, page: 7106, stat: Journal Article,

Detection of nerve growth factor receptors after gene transfer
Chao MV
1991 ;198:61-72, Methods in enzymology
— id: 14688, year: 1991, vol: 198, page: 61, stat: Journal Article,

The membrane receptor for nerve growth factor
Chao MV
1991 ;165:39-53, Current topics in microbiology & immunology
— id: 14687, year: 1991, vol: 165, page: 39, stat: Journal Article,

Effects of fimbria-fornix and angular bundle transection on expression of the p75NGFR mRNA by cells in the medial septum and diagonal band of Broca: correlations with cell survival, synaptic reorganization and sprouting
Gibbs RB; Chao MV; Pfaff DW
1991 Oct;11(3-4):207-219, Brain research. Molecular brain research
Quantitative in situ hybridization techniques were used to examine the effects of lesions which sever hippocampal cholinergic and cortical afferents on p75NGFR mRNA-expressing cells located in the medial septum (MS) and the vertical (VDB) and horizontal (HDB) limbs of the diagonal band of Broca. Animals received either bilateral transection of the fimbria/fornix, unilateral transection of the angular bundle, or sham surgery. Four days later, animals were sacrificed and sections through the MS, VDB and HDB were processed for detection of the p75NGFR mRNA using in situ hybridization techniques previously described (Mol. Brain Res., 6 (1989) 275-287). Transection of the fimbria/fornix and angular bundle differentially affected p75NGFR-expressing cells in the MS, VDB and HDB within 4 days after injury, in ways which were consistent and correlate with subsequent effects on cell survival, synaptic reorganization and growth. In particular, in the MS and VDB, transection of the fimbria/fornix resulted in a significant decrease in the size of p75NGFR-expressing cells (reductions of 25.9% and 15.1% respectively) which was accompanied by a significant reduction (37.9% and 12.7% fewer grains/cell) in relative levels of p75NGFR mRNA. In contrast, in the HDB, transection of the fimbria/fornix had no significant effect on the average size of p75NGFR-expressing cells; however, a significant increase (49%) in the mean relative level of p75NGFR mRNA was observed which may, in turn, reflect a large increase (as much as 2-3 fold) in the levels of p75NGFR mRNA expressed by a subpopulation of hippocampally projecting cholinergic neurons located in the HDB. Finally, transection of the angular bundle resulted in small, but significant increases (9.4% and 10.9%) in relative levels of p75NGFR mRNA in the MS and VDB, as well as an increase (19.6%) in the number of p75NGFR mRNA-expressing cells in the HDB, on the injured side. No increases in p75NGFR expression in the MS, VDB or HDB contralateral to the lesion were observed; however, a decrease in the size (6.9%) and message content (19.4%) of p75NGFR-expressing cells was detected in the MS contralateral to the lesion. Most importantly, all of these effects are consistent with the subsequent effects of these lesions on the survival of basal forebrain cholinergic cells, and the reorganization and growth of cholinergic afferents to the hippocampal formation.(ABSTRACT TRUNCATED AT 400 WORDS)
— id: 14680, year: 1991, vol: 11, page: 207, stat: Journal Article,

High-affinity NGF binding requires coexpression of the trk proto-oncogene and the low-affinity NGF receptor [see comments]
Hempstead BL; Martin-Zanca D; Kaplan DR; Parada LF; Chao MV
1991 Apr 25;350(6320):678-683, Nature
Nerve growth factor (NGF) interacts with two different low-affinity receptors that can be distinguished by affinity crosslinking. Reconstitution experiments by membrane fusion and transient transfection into heterologous cells indicate that high-affinity NGF binding requires coexpression and binding to both the low-affinity NGF receptor and the tyrosine kinase trk gene product. These studies reveal a new growth factor receptor-mediated mechanism of cellular differentiation involving trk and the low-affinity NGF receptor
— id: 14686, year: 1991, vol: 350, page: 678, stat: Journal Article,

The trk proto-oncogene product: a signal transducing receptor for nerve growth factor
Kaplan DR; Hempstead BL; Martin-Zanca D; Chao MV; Parada LF
1991 Apr 26;252(5005):554-558, Science
The trk proto-oncogene encodes a 140-kilodalton, membrane-spanning protein tyrosine kinase (p140prototrk) that is expressed only in neural tissues. Nerve growth factor (NGF) stimulates phosphorylation of p140prototrk in neural cell lines and in embryonic dorsal root ganglia. Affinity cross-linking and equilibrium binding experiments with 125I-labeled NGF indicate that p140prototrk binds NGF specifically in cultured cells with a dissociation constant of 10(-9) molar. The identification of p140prototrk as an NGF receptor indicates that this protein participates in the primary signal transduction mechanism of NGF
— id: 14685, year: 1991, vol: 252, page: 554, stat: Journal Article,

The trk proto-oncogene rescues NGF responsiveness in mutant NGF-nonresponsive PC12 cell lines
Loeb DM; Maragos J; Martin-Zanca D; Chao MV; Parada LF; Greene LA
1991 Sep 6;66(5):961-966, Cell
The trk tyrosine kinase proto-oncogene product gp140prototrk binds nerve growth factor (NGF) and is rapidly and selectively activated by this neurotrophic factor. To determine whether gp140prototrk is involved in transducing a functional NGF signal, PC12 cell mutants (PC12nnr) deficient in high affinity NGF binding and unresponsive to NGF were used. Northern analysis revealed that these mutant cells have greatly reduced levels of trk expression. PC12nnr cultures were transiently transfected with expression vectors encoding the full-length rat trk cDNA and assessed for responsiveness to NGF. Expression of exogenous trk rescued the capacity for NGF-promoted neurite outgrowth, cellular hypertrophy, and serum-free survival by these cells. These results indicate that gp140prototrk is necessary for functional NGF signal transduction
— id: 14681, year: 1991, vol: 66, page: 961, stat: Journal Article,

Disruption of cysteine-rich repeats of the p75 nerve growth factor receptor leads to loss of ligand binding
Yan H; Chao MV
1991 Jun 25;266(18):12099-12104, Journal of biological chemistry
Nerve growth factor (NGF) binds to a low affinity cell surface receptor (p75NGFR) which contains four extracellular repeats, rich in cysteine residues and negatively charged. We have made mutations in the receptor cDNA by inserting linkers in specific domains of the receptor. Nearly all the mutations caused a change in the predicted charge, and resulted in either an insertion or deletion in the primary sequence. Stably transfected fibroblasts were assayed for NGF binding by affinity cross-linking with 125I-NGF. Appropriate expression of the mutated receptors was monitored by rosetting with monoclonal antibodies and by metabolic labeling followed by immunoprecipitation. Although the mutant receptors were recognized by monoclonal antibodies, insertions and deletions in the third and fourth cysteine-rich regions of the receptor had a detrimental effect upon NGF binding. Insertions made outside the cysteine-rich region or in the cytoplasmic domain did not inhibit the ability of 125I-NGF to bind to the receptor, as assessed by affinity cross-linking. A chimeric human-rat NGF receptor transfected into fibroblasts indicates that NGF binding and monoclonal antibody recognition sites are separated but contained within the four cysteine repeats
— id: 14683, year: 1991, vol: 266, page: 12099, stat: Journal Article,

Chimeric NGF-EGF receptors define domains responsible for neuronal differentiation
Yan H; Schlessinger J; Chao MV
1991 Apr 26;252(5005):561-563, Science
To determine the domains of the low-affinity nerve growth factor (NGF) receptor required for appropriate signal transduction, a series of hybrid receptors were constructed that consisted of the extracellular ligand-binding domain of the human epidermal growth factor (EGF) receptor (EGFR) fused to the transmembrane and cytoplasmic domains of the human low-affinity NGF receptor (NGFR). Transfection of these chimeric receptors into rat pheochromocytoma PC12 cells resulted in appropriate cell surface expression. Biological activity mediated by the EGF-NGF chimeric receptor was assayed by the induction of neurite outgrowth in response to EGF in stably transfected cells. Furthermore, the chimeric receptor mediated nuclear signaling, as evidenced by the specific induction of transin messenger RNA, an NGF-responsive gene. Neurite outgrowth was not observed with chimeric receptors that contained the transmembrane domain from the EGFR, suggesting that the membrane-spanning region and cytoplasmic domain of the low-affinity NGFR are necessary for signal transduction
— id: 14684, year: 1991, vol: 252, page: 561, stat: Journal Article,

Monoclonal antibodies to the cell surface and a soluble form of the human nerve growth factor receptor
Clagett-Dame M; Chung C; Chao MV; DiStefano PS
1990 Dec;27(4):642-650, Journal of neuroscience research
Monoclonal antibodies (designated IIIG5, VIID1, VIIIC8, and XIF1) have been produced that bind to the human nerve growth factor receptor (NGF-R) as well as to a soluble, truncated form of the receptor (NGF-Rt). The antibodies were generated against partially purified NGF-Rt from the conditioned medium of E9b cells, a transfected mouse fibroblast cell line (Ltk-) that expresses large numbers of the low affinity form of the human NGF-R on its cell surface (Chao MV, Bothwell MA, Ross AH, Koprowski H, Lanahan AA, Buck CR, Sehgal A [1986]: Science 232:518-521). Hybridomas were screened by radiometric immunosorbent assay (RISA) and by immunoprecipitation of solubilized cell surface receptor covalently cross-linked to [125-I]-NGF. Four positive lines were cloned by limiting dilution and were found to secrete monoclonal antibodies of the IgGl,k subclass. All monoclonal antibodies bound to both NGF-R and NGF-Rt. Two monoclonal antibodies (VIID1, XIF1) immunoblotted the NGF-R from E9b cell preparations resolved on non-reducing sodium dodecyl sulfate (SDS)-polyacrylamide gels. The antibodies immunoprecipitated NGF-R from both E9b cells and from SH-SY5Y human neuroblastoma cells. The monoclonal antibodies bound to monkey (rhesis and cynomolgus) NGF-Rt, but did not cross-react with NGF-R from chick or rat. Results of antibody competition studies demonstrated that three antibodies bound to a similar or overlapping epitope on the NGF-Rt and one monoclonal antibody (IIIG5) recognized a distinct receptor epitope. Antibodies that bound to different sites on the receptor were used to develop a sensitive 2-site RISA. The 2-site RISA can be used to rapidly quantitate NGF-R and NGF-Rt in large numbers of biological samples in the absence of added [125-I]-labeled NGF
— id: 14690, year: 1990, vol: 27, page: 642, stat: Journal Article,

Identification of high- and low-affinity NGF receptors during development of the chicken central nervous system
Escandon E; Chao MV
1990 Dec;142(2):293-300, Developmental biology (Orlando)
In order to study regulation of the nerve growth factor (NGF) receptor during embryogenesis in chick brain, we have used affinity crosslinking of tissues with 125I-NGF. NGF interacts with high- and low-affinity receptors; high-affinity receptors are required for the majority of NGF's actions. Most measurements of receptor levels do not distinguish between high- and low-affinity forms of the receptor. We have used the lipophilic crosslinking agent HSAB to identify the high-affinity, functional receptor during development of the chicken central nervous system. A peak of expression during Embryonic Days 5-10 was detected in all regions of the chicken central nervous system, but, shortly after birth, only the cerebellar region displays significant levels of NGF receptor protein. The time course of expression confirms the dramatic regulation of the NGF receptor gene during defined embryonic periods. The detection of high-affinity NGF receptors in brain and neural retina provides strong evidence that NGF is involved in essential ontogenetic events in the development of the chicken central nervous system
— id: 14689, year: 1990, vol: 142, page: 293, stat: Journal Article,

Deletion of cytoplasmic sequences of the nerve growth factor receptor leads to loss of high affinity ligand binding
Hempstead BL; Patil N; Thiel B; Chao MV
1990 Jun 15;265(17):9595-9598, Journal of biological chemistry
The nerve growth factor (NGF) receptor is a glycosylated transmembrane protein present on the cell surface as both high and low affinity forms, but biological responsiveness requires interactions of NGF with the high affinity site. We have tested the effects of mutations in the intracellular domain of the receptor upon its cell surface expression and equilibrium binding of 125I-NGF. Although mutant receptors lacking the entire cytoplasmic domain are processed and expressed at the cell surface and are capable of binding to NGF, the absence of cytoplasmic sequences leads to a loss of high affinity binding and to a lack of an appropriate cross-linking pattern as assessed by N-hydroxysuccinimidyl 4-azidobenzoate photoaffinity cross-linking. These results, taken together with the highly conserved nature of these cytoplasmic sequences, implies that the interaction of the receptor with an accessory molecule is necessary to form the high affinity receptor
— id: 14691, year: 1990, vol: 265, page: 9595, stat: Journal Article,

Nerve growth factor stimulates a protein kinase in PC-12 cells that phosphorylates microtubule-associated protein-2
Miyasaka T; Chao MV; Sherline P; Saltiel AR
1990 Mar 15;265(8):4730-4735, Journal of biological chemistry
Some of the effects of nerve growth factor (NGF) may be mediated by changes in protein phosphorylation. We have identified a protein kinase from PC-12 cells that catalyzes the phosphorylation of pig brain microtubule-associated protein (MAP)-2 in vitro. This activity is stimulated 2-4-fold in extracts from cells treated with NGF or epidermal growth factor (EGF). The partial purification and characterization of this MAP kinase indicate that it is distinct from previously described NGF-stimulated protein kinases. The NGF-stimulated kinase activity is unaffected by direct addition to the assay of the heat-stable cAMP-dependent kinase peptide inhibitor, staurosporine, or K-252A, is slightly stimulated by heparin and is inhibited by sodium fluoride and calcium ions. Treatment of cells with NGF increases the activity of the kinase within 2 min. The activity declines after 10 min, and a second phase of activation is observed at 20-30 min. Comparison of its behavior on gel permeation and sucrose density gradients indicates a molecular mass in the range of 40,000 daltons. The kinase activity is specific for ATP as substrate with a Km of 12 microM. Although the pathway of activation of MAP kinase by NGF is unknown, the stimulation can be reversed by treatment of the enzyme with alkaline phosphatase, suggesting that activation involves phosphorylation of the kinase itself. The properties and hormone sensitivity of the PC-12 MAP kinase suggest that it is similar to the previously identified, growth factor-sensitive MAP kinase from 3T3-L1 adipocytes
— id: 14692, year: 1990, vol: 265, page: 4730, stat: Journal Article,

Specific neuronal expression of human NGF receptors in the basal forebrain and cerebellum of transgenic mice
Patil N; Lacy E; Chao MV
1990 Mar;4(3):437-447, Neuron
Transgenic mice carrying multiple copies of the human NGF receptor gene have been generated. Using a monoclonal antibody specific for the human receptor, we have detected specific expression in cholinergic neurons in the basal forebrain and Purkinje cells in the cerebellum during the postnatal period. Expression in the PNS was exemplified by immunostaining of sympathetic and sensory neurons during an early embryonic age. Transection of the sciatic nerve in transgenic animals resulted in induction of human NGF receptors, indicating that the inserted gene can be appropriately regulated. These transgenic mice will provide an opportunity to study the elements regulating the NGF receptor. Furthermore, the ability to obtain specific expression in transgenic mice will permit directed expression of heterologous genes in discrete cells important in the cholinergic septal-hippocampal pathway and the PNS
— id: 14693, year: 1990, vol: 4, page: 437, stat: Journal Article,

Nerve growth factor stimulates the hydrolysis of glycosylphosphatidylinositol in PC-12 cells: a mechanism of protein kinase C regulation
Chan BL; Chao MV; Saltiel AR
1989 Mar;86(6):1756-1760, Proceedings of the National Academy of Sciences of the United States of America
Treatment of PC-12 pheochromocytoma cells with nerve growth factor (NGF) results in the differentiation of these cells into a sympathetic neuron-like phenotype. Although the initial intracellular signals elicited by NGF remain unknown, some of the cellular effects of NGF are similar to those of other growth factors, such as insulin. We have investigated the involvement of a newly identified inositol-containing glycolipid in signal transduction for the actions of NGF. NGF stimulates the rapid generation of a species of diacylglycerol that is labeled with [3H]myristate but not with [3H]arachidonate. NGF stimulates [3H]myristate- or [32P]phosphate-labeled phosphatidic acid production over the same time course. Although NGF alone has no effect on the turnover of inositol phospholipids, it does stimulate the hydrolysis of glycosylphosphatidylinositol. The NGF-dependent cleavage of this lipid is accompanied by an increase in the accumulation of its polar head group, an inositol phosphate glycan, which is generated within 30-60 sec of NGF treatment. In an unresponsive PC-12 mutant cell line, neither the diacylglycerol nor inositol phosphate glycan response is detected. A possible role for the NGF-stimulated diacylglycerol is suggested by the inhibition of NGF-dependent c-fos induction by staurosporin, a potent inhibitor of protein kinase C. These results suggest that, like insulin, some of the cellular effects of NGF may be mediated by the phospholipase C-catalyzed hydrolysis of glycosylphosphatidylinositol
— id: 14696, year: 1989, vol: 86, page: 1756, stat: Journal Article,

Developmental expression of the chicken nerve growth factor receptor gene during brain morphogenesis
Escandon E; Chao MV
1989 Jun 1;47(2):187-196, Brain research. Developmental brain research
Neural development proceeds in an ordered fashion in which a variety of genetic and epigenetic factors exert an influence at well defined times. Using a cloned chicken genomic fragment for the nerve growth factor (NGF) receptor, we have detected strong expression in chicken brain at early stages of embryonic development. Expression of the receptor gene was greatly diminished at birth. This pattern of NGF receptor mRNA level was observed in all cranial regions and was further correlated with the appearance and disappearance of cell surface receptors. The transient developmental expression of NGF receptors in chick brain and the requirement for receptors to mediate NGF's effects suggests that NGF may possess a broader range of actions during development of the nervous system
— id: 14695, year: 1989, vol: 47, page: 187, stat: Journal Article,

Expression of NGF receptor in the rat forebrain detected with in situ hybridization and immunohistochemistry
Gibbs RB; McCabe JT; Buck CR; Chao MV; Pfaff DW
1989 Dec;6(4):275-287, Brain research. Molecular brain research
The expression of nerve growth factor (NGF) receptor mRNA and NGF receptor protein was examined in the adult rat basal forebrain using in situ hybridization and immunohistochemical techniques. NGF receptor mRNA and protein were detected within cells in the medial septum, diagonal band of Broca, and nucleus basalis of Meynert. Controls showed that the hybridization signal was not due to nonspecific binding of the probe to heterologous RNAs or other molecules. As expected, the distribution of NGF receptor mRNA-containing cells correlated nicely with the distribution of NGF receptor immunoreactive cells in each of these areas. These data extend previous work which suggests that neurons in these areas express the NGF receptor mRNA and manufacture functional NGF receptors. NGF receptor immunoreactivity was also detected in the arcuate nucleus of the hypothalamus, in the leptomeninges at the base of the brain and overlying the tectum, and within ependymal regions along the lateral walls of the cerebral ventricles. A few weakly stained neurons in the lateral hypothalamus and ventrolateral striatum were also consistently observed. In contrast, NGF receptor mRNA was not detected within any meningial, ependymal, or hypothalamic tissues using in situ hybridization. A cross-linking/immunoprecipitation assay demonstrated normal, membrane-bound NGF receptors within extracts of dorsal superior colliculus, ventromedial hypothalamic, and overlying meningial tissues, proving that the staining observed in these areas was not a non-specific artifact associated with the immunohistochemistry. The lack of hybridization in these areas may reflect levels of NGF receptor mRNA which are too low to be detected by the in situ hybridization methods being used. Alternatively, the staining may represent innervation of these areas by afferents whose cell bodies are located elsewhere, and whose terminals contain the NGF receptor protein
— id: 14694, year: 1989, vol: 6, page: 275, stat: Journal Article,

Nerve growth factor receptor mRNA distribution in human brain: normal levels in basal forebrain in Alzheimer's disease
Goedert M; Fine A; Dawbarn D; Wilcock GK; Chao MV
1989 Jan;5(1):1-7, Brain research. Molecular brain research
Nerve growth factor (NGF) receptor mRNA was found to be widely distributed throughout the human central nervous system, with the highest levels in the basal forebrain; this suggests that NGF may function as a retrograde trophic messenger for basal forebrain magnocellular cholinergic nerve cells. The degeneration of the latter constitutes one of the main features of Alzheimer's disease and it may be responsible for some of the cognitive impairment that characterizes the disease. No evidence was obtained for an insufficient synthesis of NGF receptor mRNA in the basal forebrain in Alzheimer's disease, where NGF receptor-like immunoreactivity was confined to neuronal cell bodies. NGF could thus be therapeutically beneficial. It could be expected to induce basal forebrain cholinergic cells to hypertrophy, synthesize more choline acetyltransferase and extend neurites
— id: 14701, year: 1989, vol: 5, page: 1, stat: Journal Article,

The nerve growth factor receptor: biochemical and structural analysis
Hempstead BL; Chao MV
1989 ;45:441-463, Recent progress in hormone research
— id: 14700, year: 1989, vol: 45, page: 441, stat: Journal Article,

Expression of functional nerve growth factor receptors after gene transfer
Hempstead BL; Schleifer LS; Chao MV
1989 Jan 20;243(4889):373-375, Science
Nerve growth factor (NGF) interacts with both high affinity (Kd = 10(-10)-10(-11)M) and low affinity (Kd = 10(-8)-10(-9)M) receptors; the binding of NGF to the high affinity receptor is correlated with biological actions of NGF. To determine whether a single NGF binding protein is common to both forms of the receptor, a full-length receptor cDNA was introduced in the NR18 cell line, an NGF receptor-deficient variant of the PC12 pheochromocytoma cell line. The transformant displayed (i) both high and low affinity receptors detectable by receptor binding; (ii) an affinity cross-linking pattern with 125I-labeled NGF similar to that of the parent PC12 cell line; and (iii) biological responsiveness to NGF as assayed by induction of c-fos transcription. These findings support the hypothesis that a single binding protein is common to both forms of the NGF receptor and suggest that an additional protein is required to produce the high affinity form of the NGF receptor
— id: 14699, year: 1989, vol: 243, page: 373, stat: Journal Article,

A moderately frequent HindIII polymorphism at the human NGFR locus (17q12----17q22)
Wright EC; Fain PR; Barker DF; Chao MV
1989 Jan 25;17(2):825-825, Nucleic acids research
— id: 14697, year: 1989, vol: 17, page: 825, stat: Journal Article,

Two polymorphic TaqI sites at the human NGFR locus (17q12----17q22)
Wright EC; Fain PR; Barker DF; Chao MV
1989 Jan 25;17(2):824-824, Nucleic acids research
— id: 14698, year: 1989, vol: 17, page: 824, stat: Journal Article,

Differential expression of the nerve growth factor receptor gene in multiple brain areas
Buck CR; Martinez HJ; Chao MV; Black IB
1988 Dec 1;44(2):259-268, Brain research. Developmental brain research
Recent work has indicated that the trophic protein, nerve growth factor (NGF), is detectable in several brain regions, in addition to its well-known localization to the periphery. In addition, a number of cholinergic populations in the brain respond to NGF by increasing enzymes involved in acetylcholine metabolism. It is well recognized that responsiveness to NGF is dependent on expression of specific receptors; we have recently detected expression by the responsive rat basal forebrain/septal, cholinergic neurons, suggesting that NGF plays a physiologic role in the development of this brain pathway. To define a potential role for NGF in other rat brain regions, we isolated a rat receptor cDNA clone to use as a probe to detect receptor message by sensitive Sl nuclease protection experiments. Our studies indicate that the NGF receptor (NGF-R) gene is expressed by anatomically, functionally and biochemically diverse populations, widely distributed in the rat brain, and is not restricted to the basal forebrain/septal region. We detect NGF receptor message in frontal cortex, hippocampus, caudate, cerebellum and olfactory bulb. Moreover, developmental profiles of steady-state quantities varied differently for each area. Our observations support the contention that NGF regulates multiple brain systems, in addition to forebrain cholinergic pathways
— id: 14702, year: 1988, vol: 44, page: 259, stat: Journal Article,

Molecular cloning and characterization of an antigen associated with early stages of melanoma tumor progression
Hotta H; Ross AH; Huebner K; Isobe M; Wendeborn S; Chao MV; Ricciardi RP; Tsujimoto Y; Croce CM; Koprowski H
1988 Jun 1;48(11):2955-2962, Cancer research
The melanoma-associated antigen ME491 is expressed strongly during the early stages of tumor progression. The ME491 gene was molecularly cloned by means of DNA-mediated gene transfer followed by screening a lambda genomic library with human repetitive Alu sequences as a probe. The cloned DNA, after transfection into mouse L-cells, generated a protein with characteristics that were indistinguishable in Western blot analysis from the ME491 antigen expressed by human melanoma cells. Repeat-free subfragments of the cloned DNA were used for further studies. By Northern blot analysis, the subfragments detected a single 1.2-kilobase mRNA in the transformants and various human melanoma cell lines. ME491 complementary DNA clones were then obtained by probing a melanoma complementary DNA library with the genomic subfragments. Nucleotide sequence analysis of the cloned complementary DNA indicated that the ME491 antigen consists of 237 amino acids (Mr 25,475) with four transmembrane regions and three putative N-glycosylation sites. No significant structural homology was observed with other proteins thus far reported. We observed that the amounts of mRNA varied greatly with different melanoma cell lines. Southern blot analysis revealed no amplification or rearrangement of the ME491 gene in the human melanoma cell lines tested, including both high and low expressors of this antigen. The ME491 gene has been mapped to chromosome region 12p12----12q13 by somatic cell hybrid analysis and more narrowly localized to 12q12----12q14 by in situ hybridization
— id: 14704, year: 1988, vol: 48, page: 2955, stat: Journal Article,

Induction of nerve growth factor receptors on cultured human melanocytes
Peacocke M; Yaar M; Mansur CP; Chao MV; Gilchrest BA
1988 Jul;85(14):5282-5286, Proceedings of the National Academy of Sciences of the United States of America
Normal differentiation and malignant transformation of human melanocytes involve a complex series of interactions during which both genetic and environmental factors play roles. At present, the regulation of these processes is poorly understood. We have induced the expression of nerve growth factor (NGF) receptors on cultured human melanocytes with phorbol 12-tetradecanoate 13-acetate and have correlated this event with the appearance of a more differentiated, dendritic morphology. Criteria for NGF receptor expression included protein accumulation and cell-surface immunofluorescent staining with a monoclonal antibody directed against the human receptor and induction of the messenger RNA species as determined by blot-hybridization studies. The presence of the receptor could also be induced by UV irradiation or growth factor deprivation. The NGF receptor is inducible in cultured human melanocytes, and we suggest that NGF may modulate the behavior of this neural crest-derived cell in the skin
— id: 14703, year: 1988, vol: 85, page: 5282, stat: Journal Article,

Efficient processing and expression of human nerve growth factor receptors in Xenopus laevis oocytes: effects on maturation
Sehgal A; Wall DA; Chao MV
1988 May;8(5):2242-2246, Molecular & cellular biology
The nerve growth factor (NGF) receptor is an integral membrane protein that is phosphorylated and heavily glycosylated. Determination of the amino acid sequence by molecular cloning indicates that the receptor is a cysteine-rich protein which contains a signal peptide sequence and spans the lipid bilayer with a single transmembrane sequence. A single mRNA of 3.8 kilobases was observed for the receptor, of which 1.5 kilobases is coding sequence. We have used microinjection of receptor RNA in Xenopus laevis oocytes to obtain cell surface expression of the receptor. The presence of NGF receptors in oocytes was verified by radioimmunoassay, specific binding of [125I]NGF, and metabolic labeling followed by immunoprecipitation. The NGF receptor protein was rapidly processed in oocytes and displayed extensive glycosylation. Furthermore, the presence of NGF receptors in oocytes potentiates the ability of progesterone to induce maturation
— id: 14705, year: 1988, vol: 8, page: 2242, stat: Journal Article,

Developmentally regulated expression of the nerve growth factor receptor gene in the periphery and brain
Buck CR; Martinez HJ; Black IB; Chao MV
1987 May;84(9):3060-3063, Proceedings of the National Academy of Sciences of the United States of America
Nerve growth factor (NGF) regulates development and maintenance of function of peripheral sympathetic and sensory neurons. A potential role for the trophic factor in brain has been detected only recently. The ability of a cell to respond to NGF is due, in part, to expression of specific receptors on the cell surface. To study tissue-specific expression of the NGF receptor gene, we have used sensitive cRNA probes for detection of NGF receptor mRNA. Our studies indicate that the receptor gene is selectively and specifically expressed in sympathetic (superior cervical) and sensory (dorsal root) ganglia in the periphery, and by the septum-basal forebrain centrally, in the neonatal rat in vivo. Moreover, examination of tissues from neonatal and adult rats reveals a marked reduction in steady-state NGF receptor mRNA levels in sensory ganglia. In contrast, a 2- to 4-fold increase was observed in the basal forebrain and in the sympathetic ganglia over the same time period. Our observations suggest that NGF receptor mRNA expression is developmentally regulated in specific areas of the nervous system in a differential fashion
— id: 14707, year: 1987, vol: 84, page: 3060, stat: Journal Article,

DEVELOPMENTALLY REGULATED EXPRESSION OF THE NERVE GROWTH-FACTOR RECEPTOR GENE IN THE PERIPHERY AND BRAIN
BUCK, CR; MARTINEZ, HJ; BLACK, IB; CHAO, MV
1987 MAY ;84(9):188-188, Journal of cellular biochemistry
— id: 105095, year: 1987, vol: 84, page: 188, stat: Journal Article,

Genetic linkage of von Recklinghausen neurofibromatosis to the nerve growth factor receptor gene
Seizinger BR; Rouleau GA; Ozelius LJ; Lane AH; Faryniarz AG; Chao MV; Huson S; Korf BR; Parry DM; Pericak-Vance MA; et al
1987 Jun 5;49(5):589-594, Cell
von Recklinghausen neurofibromatosis (VRNF) is one of the most common inherited disorders affecting the human nervous system. VRNF is transmitted as an autosomal dominant defect with high penetrance but variable expressivity. The disorder is characterized clinically by hyperpigmented patches of skin (cafe au lait macules, axillary freckles) and by multiple tumors of peripheral nerve, spinal nerve roots, and brain (neurofibromas, optic gliomas). These tumors can cause disfigurement, paralysis, blindness, and death. We have determined the chromosomal location of the VRNF gene by genetic linkage analysis using DNA markers. The VRNF gene is genetically linked to the locus encoding nerve growth factor receptor, located on the long arm of chromosome 17 in the region 17q12----17q22. However, crossovers with the VRNF locus suggest that a mutation in the nerve growth factor receptor gene itself is unlikely to be the fundamental defect responsible for the VRNF phenotype
— id: 14706, year: 1987, vol: 49, page: 589, stat: Journal Article,

GENETIC-LINKAGE OF VON RECKLINGHAUSEN NEUROFIBROMATOSIS TO THE NERVE GROWTH-FACTOR RECEPTOR GENE
SEIZINGER, BR; ROULEAU, GA; OZELIUS, LJ; LANE, AH; FARYNIARZ, AG; CHAO, MV; HUSON, S; KORF, BR; PARRY, DM; PERICAKVANCE, MA; COLLINS, FS; HOBBS, WJ; FALCONE, BG; IANNAZZI, JA; ROY, JC; STGEORGEHYSLOP, PS; TANZI, RE; BOTHWELL, MA; UPADHYAYA, M; HARPER, P; GOLDSTEIN, AE; HOOVER, DL; BADER, JL; SPENCE, MA; MULVIHILL, JJ; AYLSWORTH, AS; VANCE, JM; ROSSENWASSER, GOD; GASKELL, PC; ROSES, AD; MARTUZA, RL; BREAKEFIELD, XO; GUSELLA, JF
1987 JUN 1 ;46(1-4):690-690, Cytogenetics & cell genetics
— id: 105094, year: 1987, vol: 46, page: 690, stat: Journal Article,

DNA polymorphisms for the nerve growth factor receptor gene exclude its role in familial dysautonomia
Breakefield XO; Ozelius L; Bothwell MA; Chao MV; Axelrod F; Kramer PL; Kidd KK; Lanahan AA; Johnson DE; Ross AH; et al
1986 Dec;3(6):483-494, Molecular biology & medicine
Alleles for the single human nerve growth factor receptor gene (NGFR) on chromosome 17q can be distinguished by two polymorphic restriction sites for XmnI and one for HincII. The combined information content for haplotypes is quite high, making the NGFR locus an excellent genetic marker. Two of these polymorphisms were used to follow the inheritance of NGFR alleles in families with two or more members affected with familial dysautonomia. This rare disease is inherited in an autosomal recessive mode in the Ashkenazic Jewish population. Affected individuals show a severe depletion of NGF-dependent nerve populations from birth. Linkage analysis excluded a role for NGFR in this disease with odds of greater than 10(6):1 against the dysautonomia gene being within 1 centiMorgan of the mutation. In a previous study the gene for the beta subunit of NGF (NGFB) was also excluded in this disease. A possible role for other genes involved in NGF action or those coding for other developmentally determining neuronal factors is indicated
— id: 14708, year: 1986, vol: 3, page: 483, stat: Journal Article,

Gene transfer and molecular cloning of the human NGF receptor
Chao MV; Bothwell MA; Ross AH; Koprowski H; Lanahan AA; Buck CR; Sehgal A
1986 Apr 25;232(4749):518-521, Science
Nerve growth factor (NGF) and its receptor are important in the development of cells derived from the neural crest. Mouse L cell transformants have been generated that stably express the human NGF receptor gene transfer with total human DNA. Affinity cross-linking, metabolic labeling and immunoprecipitation, and equilibrium binding with 125I-labeled NGF revealed that this NGF receptor had the same size and binding characteristics as the receptor from human melanoma cells and rat PC12 cells. The sequences encoding the NGF receptor were molecularly cloned using the human Alu repetitive sequence as a probe. A cosmid clone that contained the human NGF receptor gene allowed efficient transfection and expression of the receptor
— id: 14709, year: 1986, vol: 232, page: 518, stat: Journal Article,

AN AUTONOMOUS MUTANT DERIVED FROM THE COLONY STIMULATING FACTOR (CSFL)-DEPENDENT CELL-LINE BACL
MORGAN, CJ; CHAO, MV; STANLEY, ER
1986 MAY ;45(6):1715-1715, Federation Proceedings (Federation of American Societies for Experimental Biology)
— id: 105096, year: 1986, vol: 45, page: 1715, stat: Journal Article,

Insulin, insulin-like growth factor II, and nerve growth factor effects on tubulin mRNA levels and neurite formation
Mill JF; Chao MV; Ishii DN
1985 Oct;82(20):7126-7130, Proceedings of the National Academy of Sciences of the United States of America
We have previously shown that insulin and the insulin-like growth factors share some important neurotrophic properties with nerve growth factor (NGF), including the capacity to enhance neurite formation. In this study, we have examined the effects of these neuritogenic agents on the expression of genes coding for important cytoskeletal proteins of axons and dendrites. Insulin specifically and coordinately increased the levels of alpha- and beta-tubulin mRNAs in human neuroblastoma SH-SY5Y cells. The dose-response curves for these increases were very similar to that for enhancement of neurite formation. Tubulin transcripts reached a transient maximum in approximately 1 day, suggesting that higher levels are important during initiation of neurites and that high levels are not required to sustain neurites once formed. Insulin-like growth factor II shared with insulin the capacity to substantially increase tubulin mRNA levels. NGF had but a small effect. Complementary mechanisms for these neurotrophic agents are suggested, because other studies show NGF and insulin can synergistically potentiate neurite formation. None of the factors altered the levels of actin mRNA. Thus, neurite formation does not seem to require a coordinate increase in actin and tubulin transcripts in SH-SY5Y cells
— id: 14710, year: 1985, vol: 82, page: 7126, stat: Journal Article,

Introduction and expression of beta-globin genes in murine erythroleukemic cells
Chao MV; Mellon P; Charnay P; Maniatis T; Axel R
1983 ;3:215-231, Gene amplification & analysis
— id: 14712, year: 1983, vol: 3, page: 215, stat: Journal Article,

The regulated expression of beta-globin genes introduced into mouse erythroleukemia cells
Chao MV; Mellon P; Charnay P; Maniatis T; Axel R
1983 Feb;32(2):483-493, Cell
We have introduced a hybrid mouse-human beta-globin gene as well as the intact human beta-globin gene into murine erythroleukemia (MEL) cells and have demonstrated that these genes are appropriately regulated during differentiation of the MEL cell in culture. The addition of chemical inducers to cotransformed cells results in a 5 to 50 fold increase in the level of mRNA transcribed from the exogenous globin gene. S1 nuclease and primer extension analyses demonstrate that these mRNAs initiate and terminate correctly. Nuclear transcription experiments indicate that induction of hybrid mRNA results at least in part from the increase in the rate of globin gene transcription. Furthermore, the induction appears to be specific for globin genes within an erythroid cell. These results permit the study of expression of the globin gene during erythroid differentiation and suggest that the specific induction of the globin gene is an inherent property of DNA sequences within or flanking the beta-globin genes. Moreover, the fact that the human and hybrid globin genes are both inducible in MEL cells suggests that these regulatory sequences are conserved between mouse and human cells
— id: 14711, year: 1983, vol: 32, page: 483, stat: Journal Article,

AN ANALYSIS OF THE C-PODA PROTOCOL FOR A SATELLITE DATA COMMUNICATION CHANNEL
CHU, WW; CHAO, MV
1983 APR 25 ;10(3):209-227, Computers & electrical engineering
— id: 105097, year: 1983, vol: 10, page: 209, stat: Journal Article,

The structure of the thymidine kinase gene promoter: nuclease hypersensitivity correlates with expression
Sweet RW; Chao MV; Axel R
1982 Dec;31(2 Pt 1):347-353, Cell
Accurate and quantitative transcription of the tk gene requires sequence elements that reside within 110 nucleotides of 5'-flanking DNA. We have determined the boundaries of a hypersensitive region in 5'DNA flanking the tk gene by analyzing the relative sensitivity of specific restriction sites clustered in this region. Five different restriction enzymes, recognizing over 50 sites in the promoter region of the tk gene, each show a preferential cleavage in nuclei at a restricted number of sites residing between positions -4 and -182. Thus the tk promoter sequences are contained entirely within a hypersensitive region. Analysis of this site in tk+ transformants, a tk- mutant and tk+ rerevertant indicates that expression of tk RNA is correlated with structural alterations in the tk promoter
— id: 14713, year: 1982, vol: 31, page: 347, stat: Journal Article,

lac Operator nucleosomes. 1. Repressor binds specifically to operator within the nucleosome core
Chao MV; Gralla JD; Martinson HG
1980 Jul 8;19(14):3254-3260, Biochemistry
We have shown that the lac repressor can recognize and bind specifically to the lac operator contained in short restriction fragments which have been complexed with the four core histones to form artificial nucleosomes and core particles. These lac reconstitutes have been well characterized, and it is apparent that the operator DNA itself is associated fully and normally with the octameric histone cores. The binding of repressor to these reconstitutes is operator dependent since nucleosomes lacking the operator sequence fail completely to bind repressor under our conditions. Moreover, binding is abolished by IPTG (isopropyl thiogalactoside), further demonstrating operator specificity. Nevertheless, sedimentation studies show that repressor binding does not involve displacement of the histone octamer. Thus, the lac repressor and the histone octamer bind simultaneously to the same DNA. lac reconstitutes, in which the DNA has been cross-linked to the histones with formaldehyde, also support simultaneous specific binding by lac repressor. Since all particles among the reconstitutes, cross-linked or not, bind repressor quantitatively, we infer that the repressor binding surface of the operator DNA always faces generally outward rather than inward toward the histone core. It is likely to be this feature of lac operator particle structure, dictated in an unknown manner by DNA sequence, that allows the simultaneous binding of histones and repressor to the same DNA region
— id: 14715, year: 1980, vol: 19, page: 3254, stat: Journal Article,

lac Operator nucleosomes. 2. lac Nucleosomes can change conformation to strengthen binding by lac repressor
Chao MV; Martinson HG; Gralla JD
1980 Jul 8;19(14):3260-3269, Biochemistry
We have shown previously that lac repressor binds specifically and quantitatively to lac operator restriction fragments which have been complexed with histones to form artificial nucleosomes (203 base pair restriction fragment) or core particles (144 base pair restriction fragment. We describe here a quantitative method for determining the equilibrium binding affinities of repressor for these lac reconstitutes. Quantitative analysis shows that the operator-histone reconstitutes may be grouped into two affinity classes: those with an affinity for repressor close to that of naked DNA and those with an affinity 2 or more orders of magnitude less than that of naked DNA. All particles in the lac nucleosome preparations bind repressor with high affinity, but the lac core particle preparations contain particles of both high and low affinities for repressor. Formaldehyde cross-linking causes all high-affinity species to suffer a 100-fold decrease in binding affinity. In contrast, there is no effect of cross-linking on species of low affinity. Therefore, the ability of a particle to be bound tightly by repressor depends on a property of the particle which is eliminated by cross-linking. Control experiments have shown that chemical damage to the operator does not accompany cross-linking. Therefore, the property sensitive to cross-linking must be the ability of the particle to change conformation. We infer that the particles of low native affinity, like cross-linked particles, are of low affinity because of an inability to facilitate repressor binding by means of this conformational change. Dimethyl suberimidate cross-linking experiments show that histone-histone cross-linking is sufficient to preclude high-affinity binding. Thus, the necessary conformational change involves a nucleosome histone core event. We find that the ability of a particle to undergo a repressor-induced facilitating conformational change appears to depend on the position of the operator along the DNA binding path of the nucleosome core. We present a general model which proposes that nucleosomes are divided into domains which function differentially to initiate conformational changes in response to physiological stimuli
— id: 14714, year: 1980, vol: 19, page: 3260, stat: Journal Article,

Accessibility of DNA sequences in lac nucleosomes
Chao, Moses Victor
[S.l. : s.n.], 1980,
'Thesis (Ph.D) -- University of California, Los Angeles, 1980'
— id: 1627, year: 1980, vol: , page: , stat: ,

DNA sequence directs placement of histone cores on restriction fragments during nucleosome formation
Chao MV; Gralla J; Martinson HG
1979 Mar 20;18(6):1068-1074, Biochemistry
Restriction fragments, 203 and 144 base pairs in length, bearing the Escherichia coli lac control region have been reconstituted with the core histones from calf thymus to form nucleosomes. By several criteria the reconstituted nucleosomes are similar to native nucleosomes obtained by micrococcal nuclease digestion of calf thymus nuclei. However, sensitive nuclease digestion studies reveal subtle and important differences between native monosomes and the lac reconstitutes. Each reconstitute consists mainly of nucleosomes containing histone cores placed nonrandomly with respect to the DNA sequence. The shorter reconstitute forms asymmetric nucleosomes as evidenced by the DNase I digestion pattern. Exonuclease III digestion followed by 5'-end analysis of the larger reconstitute suggests that, of the many possible arrangements of histone core with DNA sequence, only two are highly favored
— id: 14716, year: 1979, vol: 18, page: 1068, stat: Journal Article,

LAC REPRESSOR BINDING TO RECONSTITUTED LAC NUCLEOSOMES
CHAO, MV; MARTINSON, HG; GRALLA, JD
1979 APR 25 ;18(6):77-77, Journal of supramolecular structure
— id: 105098, year: 1979, vol: 18, page: 77, stat: Journal Article,