Angus C Wilson, 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,

Sotos syndrome and scoliosis surgical treatment: a 10-year follow-up
Corrado, Romina; Wilson, Alejandra Francheri; Tello, Carlos; Noel, Mariano; Galaretto, Eduardo; Bersusky, Ernesto
2011 Jul;20 Suppl 2:S271-S277, European spine journal
Sotos syndrome is caused by a gene deletion with an autosomal dominant pattern of inheritance. Cerebral gigantism, hypotonia and joint hyperextensibility are characteristic features of this syndrome. A percentage of these patients develop progressive scoliosis early in life. In the literature, few studies on the evolution of scoliosis in Sotos syndrome have been published. We retrospectively evaluated eight patients diagnosed with Sotos syndrome and scoliosis treated at the Garrahan Children Hospital between 1988 and March 2009. Clinical charts and imaging studies were assessed. Eight patients (19%) presented with scoliosis and seven of them (87.5%) required surgical treatment. The mean follow-up was 9.5 years (range 3-18). Mean age at first consultation was 5.2 years (range 1.1-11.2). Mean Cobb angle for scoliosis at first consultation was 34.3 degrees (range 20 degrees -42 degrees ) and the mean Cobb angle for kyphosis was 45.6 degrees (range 30 degrees -90 degrees ). Mean age at surgery was 11.2 years (range 3.7-18.10). The surgical procedures performed were instrumented posterior arthrodesis, alone or combined with anterior arthrodesis, instrumented anterior arthrodesis, while one patient is currently in treatment with growing rods. Preoperative mean Cobb angle for scoliosis was 72.3 degrees (range 54 degrees -130 degrees ) and for kyphosis was 59.8 degrees (range 30 degrees -108 degrees ); postoperative mean Cobb angle for scoliosis was 45.5 degrees (range 6 degrees -90 degrees ) and for kyphosis was 40.2 degrees (range 30 degrees -80 degrees ). There were three early complications (pleural effusion in two cases and death due to sepsis in one) and two late complications (kyphosis above the instrumentation area and dislodgement of the proximal hooks). Incidence of scoliosis in Sotos syndrome is high and thus close monitoring of patients with Sotos syndrome during growth is important for early detection of this entity. Joint hyperextensibility and hypotonia that are characteristic of the syndrome should be considered at the moment of surgery to avoid short fusions
— id: 148670, year: 2011, vol: 20 Suppl 2, page: S271, 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,

Serotonin Transporter Occupancy and the Functional Neuroanatomic Effects of Citalopram in Geriatric Depression
Smith GS; Kahn A; Sacher J; Rusjan P; van Eimeren T; Flint A; Wilson AA
2011 Dec;19(12):1016-1025, American journal of geriatric psychiatry
OBJECTIVES:: The functional neuroanatomic changes associated with selective serotonin reuptake inhibitor (SSRI) treatment have been the focus of positron emission tomography (PET) studies of cerebral glucose metabolism in geriatric depression. DESIGN:: To evaluate the underlying neurochemical mechanisms, both cerebral glucose metabolism and serotonin transporter (SERT) availability were measured before and during treatment with the SSRI, citalopram. It was hypothesized that SERT occupancy would be observed in cortical and limbic brain regions that have shown metabolic effects, as well as striatal and thalamic regions that have been implicated in prior studies in midlife patients. SETTING:: Psychiatric outpatient clinic. PARTICIPANTS:: Seven depressed patients who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for current major depressive episode were enrolled. INTERVENTION:: Patients underwent a 12-week open-label trial of the SSRI, citalopram. MEASUREMENTS:: Patients underwent high-resolution research tomography PET scans to measure changes in cerebral glucose metabolism and SERT occupancy by citalopram treatment (after 8-10 weeks of treatment). RESULTS:: Three different tracer kinetic models were applied to the [C]-DASB region-of-interest data and yielded similar results of an average of greater than 70% SERT occupancy in the striatum and thalamus during citalopram treatment. Voxel-wise analyses showed significant SERT occupancy in these regions, as well as cortical (e.g., anterior cingulate, superior and middle frontal, precuneus, and limbic (parahippocampal gyrus) areas that also showed reductions in glucose metabolism. CONCLUSION:: The findings suggest that cortical and limbic SERT occupancy may be an underlying mechanism for the regional cerebral metabolic effects of citalopram in geriatric depression
— id: 146979, year: 2011, vol: 19, page: 1016, 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,

LANA interacts with MeCP2 and nucleosomes through separate domains
Matsumura, Satoko; Persson, Linda M; Wong, LaiYee; Wilson, Angus C
2010 Mar;84(5):2318-2330, Journal of virology
Kaposi's sarcoma-associated herpesvirus (KSHV) infected cells express the latency-associated nuclear antigen (LANA) involved in regulation of host and viral gene expression and maintenance of the KSHV latent episome. Performance of these diverse functions involves a 7-amino acid chromatin-binding motif (CBM) situated at the amino terminus of LANA that is capable of binding directly to nucleosomes. LANA interacts with additional chromatin components including methyl-CpG binding protein 2 (MeCP2). Here we show that the carboxy-terminal DNA-binding/dimerization domain of LANA provides the principal interaction with MeCP2 but that this association is modulated by the CBM. Both domains are required for LANA to co-localize with MeCP2 at chromocenters, regions of extensive pericentric heterochromatin that can be imaged by fluorescence microscopy. Within MeCP2, the methyl-CpG binding domain (MBD) is the primary determinant for chromatin localization and acts together with the adjacent repression domain (CRID/TRD) to redirect LANA to chromocenters. MeCP2 facilitates repression by LANA bound to the KSHV terminal repeats, and requires the MeCP2 C terminus in addition to the MBD and CRID/TRD. LANA and MeCP2 can also cooperate to stimulate transcription of the human E2F1 promoter which lacks a LANA DNA-binding sequence but requires both the N and C terminus of LANA. The ability of LANA to establish multivalent interactions with histones and chromatin-binding proteins such as MeCP2, would enable LANA to direct regulatory complexes to specific chromosomal sites and thereby achieve stable reprogramming of cellular gene expression in latently-infected cells
— id: 106026, year: 2010, vol: 84, page: 2318, stat: Journal Article,

Wide-scale use of Notch-signaling factor CSL/RBP-J{kappa} in RTA-mediated KSHV lytic gene activation
Persson, Linda M; Wilson, Angus C
2010 Feb;84(3):1334-1347, Journal of virology
For Kaposi's sarcoma-associated herpesvirus (KSHV, HHV8), the switch from latency into active lytic replication requires RTA, the product of open reading frame 50 (ORF50). RTA activates transcription from nearly 40 early and delayed-early viral promoters mainly through interactions with cellular DNA binding proteins such as CSL/RBP-Jkappa, Oct-1, C/EBPalpha and c-Jun. Reliance on cellular co-regulators may allow KSHV to adjust its lytic program to suit different cellular contexts or interpret signals from the outside. CSL is a key component of the Notch signaling pathway and is targeted by several viruses. A search with known CSL binding sequences from cellular genes found at least 260 matches in the KSHV genome, many from regions containing known or suspected to lytic promoters. Analysis of clustered sites located immediately upstream of ORF70 (thymidylate synthase), ORF19 (tegument protein) and ORF47 (glycoprotein L) uncovered RTA-responsive promoters that were validated using mRNA isolated from KSHV-infected cells undergoing lytic reactivation. Notably, ORF19 behaves as a true-late gene, indicating that RTA regulates all three phases of the lytic program. For each new promoter, the response to RTA was dependent on CSL, and five of the ten candidate sites were shown to bind CSL in vitro. Analysis of individuals sites highlighted the importance of a cytosine residue flanking the core CSL binding sequence. These findings broaden the role for CSL in coordinating the KSHV lytic gene expression program and help define a signature motif for functional CSL sites within the viral genome
— id: 106027, year: 2010, vol: 84, page: 1334, stat: Journal Article,

Activation of host translational control pathways by a viral developmental switch
Arias, Carolina; Walsh, Derek; Harbell, Jack; Wilson, Angus C; Mohr, Ian
2009 Mar;5(3):e1000334-e1000334, PLoS pathogens
In response to numerous signals, latent herpesvirus genomes abruptly switch their developmental program, aborting stable host-cell colonization in favor of productive viral replication that ultimately destroys the cell. To achieve a rapid gene expression transition, newly minted capped, polyadenylated viral mRNAs must engage and reprogram the cellular translational apparatus. While transcriptional responses of viral genomes undergoing lytic reactivation have been amply documented, roles for cellular translational control pathways in enabling the latent-lytic switch have not been described. Using PEL-derived B-cells naturally infected with KSHV as a model, we define efficient reactivation conditions and demonstrate that reactivation substantially changes the protein synthesis profile. New polypeptide synthesis correlates with 4E-BP1 translational repressor inactivation, nuclear PABP accumulation, eIF4F assembly, and phosphorylation of the cap-binding protein eIF4E by Mnk1. Significantly, inhibiting Mnk1 reduces accumulation of the critical viral transactivator RTA through a post-transcriptional mechanism, limiting downstream lytic protein production, and impairs reactivation efficiency. Thus, herpesvirus reactivation from latency activates the host cap-dependent translation machinery, illustrating the importance of translational regulation in implementing new developmental instructions that drastically alter cell fate
— id: 98991, year: 2009, vol: 5, page: e1000334, stat: Journal Article,

Association of C-terminal ubiquitin hydrolase BAP1 with cell cycle regulator HCF-1
Misaghi, Shahram; Ottosen, Soren; Izrael-Tomasevic, Anita; Arnott, David; Lamkanfi, Mohamed; Lee, James; Liu, Jinfeng; O'Rourke, Karen; Dixit, Vishva M; Wilson, Angus C
2009 Apr;29(8):2181-2192, Molecular & cellular biology
Protein ubiquitination provides an efficient and reversible mechanism to regulate cell cycle progression and checkpoint control. Numerous regulatory proteins direct the addition of ubiquitin to lysine residues on target proteins and these are countered by an army of deubiquitinating enzymes (DUBs). BRCA1-associated protein-1 (Bap1) is a ubiquitin carboxy-terminal hydrolase and is frequently mutated in lung and sporadic breast tumors. Bap1 can suppress growth of lung cancer cells in athymic nude mice and this requires its DUB activity. Here we show that Bap1 interacts with host cell factor-1 (HCF-1), a transcriptional cofactor found in a number of important regulatory complexes. Bap1 binds to the HCF-1 beta-propeller using a variant of the HCF-binding motif (HBM) found in herpes simplex virus VP16 and other HCF-interacting proteins. HCF-1 is K48 and K63 ubiquitinated, with a major site of linkage at lysines-1807/1808 in the HCF-1C subunit. Expression of a catalytically inactive version of Bap1 results in the selective accumulation of K48 ubiquitinated polypeptides. Depletion of Bap1 using siRNA results in a modest accumulation of HCF-1C suggesting that Bap1 helps to control cell proliferation by regulating HCF-1 protein levels and by associating with genes involved in the G1-S transition
— id: 94315, year: 2009, vol: 29, page: 2181, stat: Journal Article,

Setting the stage for S phase
Wilson, Angus C
2007 Jul 20;27(2):176-177, Molecular cell
In a recent issue of Molecular Cell, Tyagi et al. (2007) show that E2F1, a positive regulator of S phase entry, recruits cofactor HCF-1 and associated hSet1/MLL histone H3 lysine 4 methyltransferase complex, facilitating the activation of genes required for proliferation
— id: 73584, year: 2007, vol: 27, page: 176, stat: Journal Article,

Activation of the Kaposi's Sarcoma-Associated Herpesvirus Major Latency Locus by the Lytic Switch Protein RTA (ORF50)
Matsumura, Satoko; Fujita, Yuriko; Gomez, Evan; Tanese, Naoko; Wilson, Angus C
2005 Jul;79(13):8493-8505, Journal of virology
Kaposi's sarcoma-associated herpesvirus (KSHV) maintains a latent infection in primary effusion lymphoma cells but can be induced to enter full lytic replication by exposure to a variety of chemical inducing agents or by expression of the KSHV-encoded replication and transcription activator (RTA) protein. During latency, only a few viral genes are expressed, and these include the three genes of the so-called latency transcript (LT) cluster: v-FLIP (open reading frame 71 [ORF71]), v-cyclin (ORF72), and latency-associated nuclear antigen (ORF73). During latency, all three open reading frames are transcribed from a common promoter as part of a multicistronic mRNA. Subsequent alternative mRNA splicing and internal ribosome entry allows for the expression of each protein. Here, we show that transcription of LT cassette mRNA can be induced by RTA through the activation of a second promoter (LT(i)) immediately downstream of the constitutively active promoter (LT(c)). We identified a minimal cis-regulatory region, which overlaps with the promoter for the bicistronic K14/v-GPCR delayed early gene that is transcribed in the opposite direction. In addition to a TATA box at -30 relative to the LT(i) mRNA start sites, we identified three separate RTA response elements that are also utilized by the K14/v-GPCR promoter. Interestingly, LT(i) is unresponsive to sodium butyrate, a potent inducer of lytic replication. This suggests there is a previously unrecognized class of RTA-responsive promoters that respond to direct, but not indirect, induction of RTA. These studies highlight the fact that induction method can influence the precise program of viral gene expression during early events in reactivation and also suggest a mechanism by which RTA contributes to establishment of latency during de novo infections
— id: 56176, year: 2005, vol: 79, page: 8493, stat: Journal Article,

Transcripts encoding K12, v-FLIP, v-cyclin, and the microRNA cluster of Kaposi's sarcoma-associated herpesvirus originate from a common promoter
Pearce, Michael; Matsumura, Satoko; Wilson, Angus C
2005 Nov;79(22):14457-14464, Journal of virology
Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of three malignancies associated with AIDS and immunosuppression. Tumor cells harbor latent virus and express kaposin (open reading frame [ORF] K12), v-FLIP (ORF 71), v-Cyclin (ORF 72), and latency-associated nuclear antigen (LANA; ORF 73). ORFs 71 to 73 are transcribed as multicistronic RNAs initiating from adjacent constitutive and inducible promoters upstream of ORF 73. Here we characterize a third promoter embedded within the ORF 71-to-73 transcription unit specifying transcripts that encode ORF 71/72 or K12. These transcripts may also be the source of 11 microRNAs arranged as a cluster between K12 and ORF 71. Our studies reveal a complex arrangement of interlaced transcription units, incorporating four important protein-encoding genes required for latency and pathogenesis and the entire KSHV microRNA repertoire
— id: 62365, year: 2005, vol: 79, page: 14457, stat: Journal Article,

Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen induces a strong bend on binding to terminal repeat DNA
Wong, Lai-Yee; Wilson, Angus C
2005 Nov;79(21):13829-13836, Journal of virology
During latency, the Kaposi's sarcoma-associated herpesvirus genome is maintained as a circular episome, replicating in synchrony with host chromosomes. Replication requires the latency-associated nuclear antigen (LANA) and an origin of latent DNA replication located in the viral terminal repeats, consisting of two LANA binding sites (LBSs) and a GC-rich sequence. Here, we show that the recruitment of a LANA dimer to high-affinity site LBS-1 bends DNA by 57 degrees and towards the major groove. The cooccupancy of LBS-1 and lower-affinity LBS-2 induces a symmetrical bend of 110 degrees . By changing the origin architecture, LANA may help to assemble a specific nucleoprotein structure important for the initiation of DNA replication
— id: 58978, year: 2005, vol: 79, page: 13829, stat: Journal Article,

Transcriptional activation by the Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen is facilitated by an N-terminal chromatin-binding motif
Wong, Lai-Yee; Matchett, Gerald A; Wilson, Angus C
2004 Sep;78(18):10074-10085, Journal of virology
In immunocompromised patients, infection with Kaposi's sarcoma-associated herpesvirus (KSHV) can give rise to Kaposi's sarcoma and several lymphoproliferative disorders. In these tumors, KSHV establishes a latent infection in many of the rapidly proliferating and morphologically abnormal cells. Only a few viral gene products are expressed by the latent virus, and one of the best characterized is the latency-associated nuclear antigen (LANA), a nuclear protein required for the maintenance of viral episomal DNA in the dividing host cell. LANA can also activate or repress an assortment of cellular and viral promoters and may contribute to pathogenesis by allowing the proliferation and survival of host cells. Here we show that activation of the human E2F1 and cyclin-dependent kinase-2 (CDK2) promoters requires elements from both the N- and C-terminal regions of LANA. Deletion of the first 22 amino acids, which are necessary for episome tethering, does not affect nuclear localization but significantly reduces transactivation. Within the deleted peptide, we have identified a short sequence, termed the chromatin-binding motif (CBM), that binds tightly to interphase and mitotic chromatin. A second chromatin-binding activity resides in the C terminus but is not sufficient for optimal transactivation. Alanine substitutions within the CBM reveal a close correlation between the transactivation and chromatin binding activities, implying a mechanistic link. In contrast to promoter activation, we find that the 223 amino acids of the LANA C terminus are sufficient to inhibit p53-mediated activation of the human BAX promoter, indicating that the CBM is not required for all transcription-related functions
— id: 45302, year: 2004, vol: 78, page: 10074, stat: Journal Article,

HCF-1 functions as a coactivator for the zinc finger protein Krox20
Luciano, Randy L; Wilson, Angus C
2003 Dec 19;278(51):51116-51124, Journal of biological chemistry
HCF-1 is a transcriptional cofactor required for activation of herpes simplex virus immediate-early genes by VP16 as well as less clearly defined roles in cell proliferation, cytokinesis, and spliceosome formation. It is expressed as a large precursor that undergoes proteolysis to yield two subunits that remain stably associated. VP16 uses a degenerate 4-amino acid sequence, known as the HCF-binding motif, to bind to a six-bladed beta-propeller domain at the N terminus of HCF-1. Functional HCF-binding motifs are also found in LZIP and Zhangfei, two cellular bZIP transcription factors of unknown function. Here we show that the HCF-binding motif occurs in a wide spectrum of DNA-binding proteins and transcriptional cofactors. Three well characterized examples were further analyzed for their ability to use HCF-1 as a coactivator. Krox20, a zinc finger transcription factor required for Schwann cell differentiation, and E2F4, a cell cycle regulator, showed a strong requirement for functional HCF-1 to activate transcription. In contrast, activation by estrogen receptor-alpha did not display HCF dependence. In Krox20, the HCF-binding motif lies within the N-terminal activation domain and mutation of this sequence diminishes both transactivation and association with the HCF-1 beta-propeller. The activation domain in the C-terminal subunit of HCF-1 contributes to activation by Krox20, possibly through recruitment of p300. These results suggest that HCF-1 is recruited by many different classes of cellular transcription factors and is therefore likely to be required for a variety of cellular processes including cell cycle progression and development
— id: 48178, year: 2003, vol: 278, page: 51116, stat: Journal Article,

Molecular cloning of Drosophila HCF reveals proteolytic processing and self-association of the encoded protein
Mahajan, Shahana S; Johnson, Kristina M; Wilson, Angus C
2003 Feb;194(2):117-126, Journal of cellular physiology
HCF-1 functions as a coactivator for herpes simplex virus VP16 and a number of mammalian transcription factors. Mature HCF-1 is composed of two subunits generated by proteolytic cleavage of a larger precursor at six centrally-located HCF(PRO) repeats. The resulting N- and C-terminal subunits remain tightly associated via two complementary pairs of self-association domains: termed SAS1N-SAS1C and SAS2N-SAS2C. Additional HCF proteins have been identified in mammals (HCF-2) and Caenorhabditis elegans (CeHCF). Both contain well-conserved SAS1 domains but do not undergo proteolytic processing. Thus, the significance of the cleavage and self-association of HCF-1 remains enigmatic. Here, we describe the isolation of the Drosophila HCF homologue (dHCF) using a genetic screen based on conservation of the SAS1 interaction. The N-terminal beta-propeller domain of dHCF supports VP16-induced complex formation and is more similar to mammalian HCF-1 than other homologues. We show that full-length dHCF expressed in Drosophila cells undergoes proteolytic cleavage giving rise to tightly associated N- and C-terminal subunits. As with HCF-1, the SAS1N and SAS1C elements of dHCF are separated by a large central region, however, this sequence lacks obvious homology to the HCF(PRO) repeats required for HCF-1 cleavage. The conservation of HCF processing in insect cells argues that formation of separate N- and C-terminal subunits is important for HCF function
— id: 35188, year: 2003, vol: 194, page: 117, stat: Journal Article,

An activation domain in the C-terminal subunit of HCF-1 is important for transactivation by VP16 and LZIP
Luciano, Randy L; Wilson, Angus C
2002 Oct 15;99(21):13403-13408, Proceedings of the National Academy of Sciences of the United States of America
In herpes simplex virus, lytic replication is initiated by the viral transactivator VP16 acting with cellular cofactors Oct-1 and HCF-1. Although this activator complex has been studied in detail, the role of HCF-1 remains elusive. Here, we show that HCF-1 contains an activation domain (HCF-1(AD)) required for maximal transactivation by VP16 and its cellular counterpart LZIP. Expression of the VP16 cofactor p300 augments HCF-1(AD) activity, suggesting a mechanism of synergy. Infection of cells lacking the HCF-1(AD) leads to reduced viral immediate-early gene expression and lowered viral titers. These findings underscore the importance of HCF-1 to herpes simplex virus replication and VP16 transactivation
— id: 39588, year: 2002, vol: 99, page: 13403, stat: Journal Article,

Interaction of HCF-1 with a cellular nuclear export factor
Mahajan, Shahana S; Little, Markus M; Vazquez, Rafael; Wilson, Angus C
2002 Nov 15;277(46):44292-44299, Journal of biological chemistry
HCF-1 is a cellular protein required by VP16 to activate the herpes simplex virus (HSV) immediate-early genes. VP16 is a component of the viral tegument and, after release into the cell, binds to HCF-1 and translocates to the nucleus to form a complex with the POU domain protein Oct-1 and a VP16-responsive DNA sequence. This VP16-induced complex boosts transcription of the viral immediate-early genes and initiates lytic replication. In uninfected cells, HCF-1 functions as a coactivator for the cellular transcription factors LZIP and GABP and also plays an essential role in cell proliferation. VP16 and LZIP share a tetrapeptide HCF-binding motif recognized by the beta-propeller domain of HCF-1. Here we describe a new cellular HCF-1 beta-propeller domain binding protein, termed HPIP, which contains a functional HCF-binding motif and a leucine-rich nuclear export sequence. We show that HPIP shuttles between the nucleus and cytoplasm in a CRM1-dependent manner and that overexpression of HPIP leads to accumulation of HCF-1 in the cytoplasm. These data suggest that HPIP regulates HCF-1 activity by modulating its subcellular localization. Furthermore, HPIP-mediated export may provide the pool of cytoplasmic HCF-1 required for import of virion-derived VP16 into the nucleus
— id: 39404, year: 2002, vol: 277, page: 44292, stat: Journal Article,

Transcription
Tanese N; Wilson AC
2001 ;2001:?-?, McGraw-Hill yearbook of science & technology
— id: 19699, year: 2001, vol: 2001, page: ?, stat: Journal Article,

N-terminal transcriptional activation domain of LZIP comprises two LxxLL motifs and the Host Cell Factor-1 binding motif
Luciano RL; Wilson AC
2000 Sep 26;97(20):10757-10762, Proceedings of the National Academy of Sciences of the United States of America
Host Cell Factor-1 (HCF-1, C1) was first identified as a cellular target for the herpes simplex virus transcriptional activator VP16. Association between HCF and VP16 leads to the assembly of a multiprotein enhancer complex that stimulates viral immediate-early gene transcription. HCF-1 is expressed in all cells and is required for progression through G(1) phase of the cell cycle. In addition to VP16, HCF-1 associates with a cellular bZIP protein known as LZIP (or Luman). Both LZIP and VP16 contain a four-amino acid HCF-binding motif, recognized by the N-terminal beta-propeller domain of HCF-1. Herein, we show that the N-terminal 92 amino acids of LZIP contain a potent transcriptional activation domain composed of three elements: the HCF-binding motif and two LxxLL motifs. LxxLL motifs are found in a number of transcriptional coactivators and mediate protein-protein interactions, notably recognition of the nuclear hormone receptors. LZIP is an example of a sequence-specific DNA-binding protein that uses LxxLL motifs within its activation domain to stimulate transcription. The LxxLL motifs are not required for association with the HCF-1 beta-propeller and instead interact with other regions in HCF-1 or recruit additional cofactors
— id: 11503, year: 2000, vol: 97, page: 10757, stat: Journal Article,

Mutations in host cell factor 1 separate its role in cell proliferation from recruitment of VP16 and LZIP
Mahajan SS; Wilson AC
2000 Feb;20(3):919-928, Molecular & cellular biology
Host cell factor 1 (HCF-1) is a nuclear protein required for progression through G(1) phase of the cell cycle and, via its association with VP16, transcriptional activation of the herpes simplex virus immediate-early genes. Both functions require a six-bladed beta-propeller domain encoded by residues 1 to 380 of HCF-1 as well as an additional amino-terminal region. The beta-propeller domain is well conserved in HCF homologues, consistent with a critical cellular function. To date, the only known cellular target of the beta-propeller is a bZIP transcription factor known as LZIP or Luman. Whether the interaction between HCF-1 and LZIP is required for cell proliferation remains to be determined. In this study, we used directed mutations to show that all six blades of the HCF-1 beta-propeller contribute to VP16-induced complex assembly, association with LZIP, and cell cycle progression. Although LZIP and VP16 share a common tetrapeptide HCF-binding motif, our results reveal profound differences in their interaction with HCF-1. Importantly, with several of the mutants we observe a poor correlation between the ability to associate with LZIP and promote cell proliferation in the context of the full HCF-1 amino terminus, arguing that the HCF-1 beta-propeller domain must target other cellular transcription factors in order to contribute to G(1) progression
— id: 11872, year: 2000, vol: 20, page: 919, stat: Journal Article,

Carboxy terminus of human herpesvirus 8 latency-associated nuclear antigen mediates dimerization, transcriptional repression, and targeting to nuclear bodies
Schwam DR; Luciano RL; Mahajan SS; Wong L; Wilson AC
2000 Sep;74(18):8532-8540, Journal of virology
Human herpesvirus 8 (HHV-8; also known as Kaposi's sarcoma-associated herpesvirus) is the causative agent of Kaposi's sarcoma and certain B-cell lymphomas. In most infected cells, HHV-8 establishes a latent infection characterized by the expression of latency-associated nuclear antigen (LANA) encoded by open reading frame 73. Although unrelated by sequence, there are functional similarities between LANA and the EBNA-1 protein of Epstein-Barr virus. Both accumulate as subnuclear speckles and are required for maintenance of the viral episome. EBNA-1 also regulates viral gene expression and is required for cell immortalization, suggesting that LANA performs similar functions in the context of HHV-8 infection. Here we show that LANA forms stable dimers, or possibly higher-order multimers, and that this is mediated by a conserved region in the C terminus. By expressing a series of truncations, we show that both the N- and C-terminal regions localize to the nucleus, although only the C terminus accumulates as nuclear speckles characteristic of the intact protein. Lastly, we show that LANA can function as a potent transcriptional repressor when tethered to constitutively active promoters via a heterologous DNA-binding domain. Domains in both the N and C termini mediate repression. This suggests that one function of LANA is to suppress the expression of the viral lytic genes or cellular genes involved in the antiviral response
— id: 11534, year: 2000, vol: 74, page: 8532, stat: Journal Article,

HCF-1 amino- and carboxy-terminal subunit association through two separate sets of interaction modules: involvement of fibronectin type 3 repeats
Wilson AC; Boutros M; Johnson KM; Herr W
2000 Sep;20(18):6721-6730, Molecular & cellular biology
When herpes simplex virus infects permissive cells, the viral regulatory protein VP16 forms a specific complex with HCF-1, a preexisting nuclear protein involved in cell proliferation. The majority of HCF-1 in the cell is a complex of associated amino (HCF-1(N))- and carboxy (HCF-1(C))-terminal subunits that result from an unusual proteolytic processing of a large precursor polypeptide. Here, we have characterized the structure and function of sequences required for HCF-1(N) and HCF-1(C) subunit association. HCF-1 contains two matched pairs of self-association sequences called SAS1 and SAS2. One of these matched association sequences, SAS1, consists of a short 43-amino-acid region of the HCF-1(N) subunit, which associates with a carboxy-terminal region of the HCF-1(C) subunit that is composed of a tandem pair of fibronectin type 3 repeats, a structural motif known to promote protein-protein interactions. Unexpectedly, the related protein HCF-2, which is not proteolyzed, also contains a functional SAS1 association element, suggesting that this element does not function solely to maintain HCF-1(N) and HCF-1(C) subunit association. HCF-1(N) subunits do not possess a nuclear localization signal. We show that, owing to a carboxy-terminal HCF-1 nuclear localization signal, HCF-1(C) subunits can recruit HCF-1(N) subunits to the nucleus
— id: 19696, year: 2000, vol: 20, page: 6721, stat: Journal Article,

Herpes simplex virus transactivator VP16 discriminates between HCF-1 and a novel family member, HCF-2
Johnson KM; Mahajan SS; Wilson AC
1999 May;73(5):3930-3940, Journal of virology
Herpes simplex virus infection is initiated by VP16, a viral transcription factor that activates the viral immediate-early (IE) genes. VP16 does not recognize the IE gene promoters directly but instead forms a multiprotein complex with Oct-1 and HCF-1, a ubiquitous nuclear protein required for progression through the G1 phase of the cell cycle. The functional significance of recruiting HCF-1 to the VP16-induced complex is not understood. Here we describe the identification of a second HCF-like protein, designated HCF-2. HCF-2 is smaller than HCF-1 but shares three regions of strong amino acid sequence homology, including the beta-propeller domain required for association with VP16. HCF-2 is expressed in many tissues, especially the testis, and shows a more dynamic pattern of subcellular localization than HCF-1. Although HCF-2 associates with VP16 and can support complex assembly with Oct-1 and DNA, it is significantly less efficient than HCF-1. A similar preference is shown by LZIP, a cellular counterpart of VP16. Analysis of chimeric proteins showed that differences between the fifth and sixth kelch repeats of the beta-propeller domains from HCF-1 and HCF-2 dictate this selectivity. These results reveal an unexpected level of specificity in the recruitment of HCF-1 to the VP16-induced complex, paralleling the preferential selection of Oct-1 rather than the closely related POU domain protein Oct-2. Implications for regulation of the viral life cycle are discussed
— id: 6081, year: 1999, vol: 73, page: 3930, stat: Journal Article,

A single-point mutation in HCF causes temperature-sensitive cell-cycle arrest and disrupts VP16 function
Goto H; Motomura S; Wilson AC; Freiman RN; Nakabeppu Y; Fukushima K; Fujishima M; Herr W; Nishimoto T
1997 Mar 15;11(6):726-737, Genes & development
The temperature-sensitive BHK21 hamster cell line tsBN67 ceases to proliferate at the nonpermissive temperature after a lag of one to a few cell divisions, and the arrested cells display a gene expression pattern similar to that of serum-starved cells. The temperature-sensitive phenotype is reversible and results from a single missense mutation--proline to serine at position 134--in HCF, a cellular protein that, together with the viral protein VP16, activates transcription of herpes simplex virus (HSV) immediate-early genes. The tsBN67 HCF mutation also prevents VP16 activation of transcription at the nonpermissive temperature. The finding that the same point mutation in HCF disrupts both VP16 function and the cell cycle suggests that HCF plays a role in cell-cycle progression in addition to VP16-dependent transcription
— id: 8394, year: 1997, vol: 11, page: 726, stat: Journal Article,

VP16 targets an amino-terminal domain of HCF involved in cell cycle progression
Wilson AC; Freiman RN; Goto H; Nishimoto T; Herr W
1997 Oct;17(10):6139-6146, Molecular & cellular biology
The herpes simplex virus (HSV) regulatory protein VP16 activates HSV immediate-early gene transcription through formation of a multiprotein-DNA complex on viral promoters that includes the preexisting nuclear proteins HCF and Oct-1. The HCF protein is a complex of amino- and carboxy-terminal polypeptides derived from a large (approximately 2,000-amino-acid) precursor by proteolytic processing. Here we show that a 361-residue amino-terminal region of HCF is sufficient to bind VP16, stabilize VP16-induced complex assembly with Oct-1 and DNA, and activate transcription in vivo. This VP16 interaction region contains six kelch-like repeats, a degenerate repeat motif that is likely to fold as a distinctive beta-propeller structure. The third HCF kelch repeat includes a proline residue (P134) that is mutated to serine in hamster tsBN67 cells, resulting in a temperature-sensitive defect in cell proliferation. This missense mutation also prevents direct association between HCF and VP16, suggesting that VP16 mimics a cellular factor required for cell proliferation. Rescue of the tsBN67 cell proliferation defect by HCF, however, requires both the VP16 interaction domain and an adjacent basic region, indicating that HCF utilizes multiple regions to promote cell cycle progression
— id: 17836, year: 1997, vol: 17, page: 6139, stat: Journal Article,

The gene encoding the VP16-accessory protein HCF (HCFC1) resides in human Xq28 and is highly expressed in fetal tissues and the adult kidney
Wilson AC; Parrish JE; Massa HF; Nelson DL; Trask BJ; Herr W
1995 Jan 20;25(2):462-468, Genomics
After herpes simplex virus (HSV) infection, the viral regulatory protein VP16 activates transcription of the HSV immediate-early promoters by directing complex formation with two cellular proteins, the POU-homeodomain transcription factor Oct-1 and the host cell factor HCF. The function of HCF in uninfected cells is unknown. Here we show by fluorescence in situ hybridization and somatic cell hybrid analysis that the gene encoding human HCF, HCFC1, maps to the q28 region of the X chromosome. Yeast artificial chromosome and cosmid mapping localizes the HCFC1 gene within 100 kb distal of the renal vasopressin type-2 receptor (V2R) gene and adjacent to the renin-binding protein gene (RENBP). The HCFC1 gene is apparently unique. HCF transcripts and protein are most abundant in fetal and placental tissues and cell lines, suggesting a role in cell proliferation. In adults, HCF protein is abundant in the kidney, but not in the brain, a site of latent HSV infection and where HCF levels may influence progression of HSV infection
— id: 8393, year: 1995, vol: 25, page: 462, stat: Journal Article,

The HCF repeat is an unusual proteolytic cleavage signal
Wilson AC; Peterson MG; Herr W
1995 Oct 15;9(20):2445-2458, Genes & development
The herpes simplex virus VP16-associated protein HCF is a nuclear host-cell factor that exists as a family of polypeptides encoded by a single gene. The mature HCF polypeptides are amino- and carboxy-terminal fragments of a large approximately 300-kD precursor protein that arise through cleavage at one or more centrally located sites. The sites of cleavage are the HCF repeats, highly conserved 26-amino-acid sequences repeated six times in the HCF precursor protein. The HCF repeat alone is sufficient to induce cleavage of a heterologous protein, and cleavage occurs at a defined site--PPCE/THET--within the HCF repeat. Alanine-scan mutagenesis was used to identify a large 18-amino-acid segment of the HCF repeat that is important to induce cleavage of a heterologous protein. Even though HCF is cleaved, the majority of amino- and carboxy-terminal cleavage products remain tightly, albeit noncovalently, associated. Modulation of this noncovalent association may provide a mechanism for regulating HCF activity. For example, the cleaved products of an alternative mRNA splicing variant of HCF do not remain associated
— id: 8198, year: 1995, vol: 9, page: 2445, stat: Journal Article,

Combinatorial control of transcription: the herpes simplex virus VP16-induced complex
Wilson AC; Cleary MA; Lai JS; LaMarco K; Peterson MG; Herr W
1993 ;58(18):167-178, Cold Spring Harbor symposia on quantitative biology
— id: 19697, year: 1993, vol: 58, page: 167, stat: Journal Article,

The VP16 accessory protein HCF is a family of polypeptides processed from a large precursor protein
Wilson AC; LaMarco K; Peterson MG; Herr W
1993 Jul 16;74(1):115-125, Cell
Upon lytic infection of permissive cells, the herpes simplex virus (HSV) transactivator protein VP16 associates with an accessory protein termed host cell factor (HCF). Binding to HCF activates VP16 for association with the octamer motif-binding protein Oct-1, to form a multiprotein-DNA complex responsible for activating transcription of the HSV immediate early genes. We show that HCF comprises a series of related polypeptides that range from 110 to 300 kd, all of which are encoded by a single gene. Although there is no obvious sequence similarity between HCF and other known proteins, HCF contains eight repeats of a new 26 amino acid motif. cDNAs encoding HCF predict a large open reading frame of 2035 codons. When expressed in human cells, this large open reading frame encodes both the 300 kd and smaller HCF polypeptides, indicating that the smaller polypeptides arise by processing of the 300 kd protein
— id: 8197, year: 1993, vol: 74, page: 115, stat: Journal Article,