Thomas F Franke, Ph.D., M.D.

Androgen receptor levels are upregulated by Akt in prostate cancer
Ha, Susan; Ruoff, Rachel; Kahoud, Nicole; Franke, Thomas F; Logan, Susan K
2011 Apr;18(2):245-255, Endocrine-related cancer
Multiple lines of evidence suggest a functional link between the androgen receptor (AR) and the serine/threonine kinase Akt in the development and progression of prostate cancer. To investigate the impact of Akt activity on AR homeostasis, we treated androgen-dependent LNCaP and LAPC-4 prostate cancer cells with Akt inhibitor. Akt inhibition decreased AR expression, suggesting that Akt activity was required for regulation of AR protein levels. However, while androgen-independent LNCaP-abl cells also showed diminished AR protein levels in response to Akt inhibition, treatment of androgen-independent LNCaP-AI cells failed to alter AR protein levels upon similar treatment, suggesting that AR protein levels in these androgen-independent prostate cells were regulated by mechanisms independent of Akt activation. Regulation of AR, downstream of activated Akt, also was observed in vivo when examining transgenic mice that overexpress constitutively active mutant myristoylated (myr)-Akt1 in the prostate. Transgenic mice expressing activated myr-Akt1 exhibited higher levels of AR mRNA and protein. Expression of activated myr-Akt1 did not alter prostate cell growth and no significant size differences between prostate tissues derived from transgenic animals were observed when comparing transgenic mice with wild-type mice. Still, transgenic mice overexpressing Akt exhibited higher levels of gammaH2AX and phosphorylated Chk2 in prostate tissue. These changes in markers associated with oncogene-induced senescence confirmed significant altered signaling in the transgenic mouse model. Overall, results presented here suggest that AR levels are regulated by the Akt pathway
— id: 136566, year: 2011, vol: 18, page: 245, stat: Journal Article,

PI3K/Akt: getting it right matters
Franke, T F
2008 Nov 13;27(50):6473-6488, Oncogene
The Akt serine/threonine kinase (also called protein kinase B) has emerged as a critical signaling molecule within eukaryotic cells. Significant progress has been made in clarifying its regulation by upstream kinases and identifying downstream mechanisms that mediate its effects in cells and contribute to signaling specificity. Here, we provide an overview of present advances in the field regarding the function of Akt in physiological and pathological cell function within a more generalized framework of Akt signal transduction. An emphasis is placed on the involvement of Akt in human diseases ranging from cancer to metabolic dysfunction and mental disease
— id: 90041, year: 2008, vol: 27, page: 6473, stat: Journal Article,

Intracellular signaling by Akt: bound to be specific
Franke, Thomas F
2008 ;1(24):pe29-pe29, Science signaling
Over the past decade, the serine/threonine kinase Akt (also known as protein kinase B) has emerged as a critical signaling molecule within eukaryotic cells. In addition to the research required for the clarification of its regulation by upstream kinases and phosphatases, progress has been made in the identification of Akt-binding partners that modulate its activation, regulate its kinase activity, and define its impact on downstream biological responses. Studies of Akt-binding molecules have highlighted novel mechanisms involved in the regulation of signaling downstream of activated phosphoinositide 3-kinase. Akt-interacting molecules may have important roles in Akt signal transduction both under physiological and pathological conditions
— id: 80336, year: 2008, vol: 1, page: pe29, stat: Journal Article,

Inhibition of 5-HT(1A) receptor-dependent cell survival by cAMP/protein kinase A: Role of protein phosphatase 2A and Bax
Hsiung, Shu-chi; Tin, Adrianne; Tamir, Hadassah; Franke, Thomas F; Liu, Kuo-peing
2008 May 5;86(10):2326-2338, Journal of neuroscience research
Serotonergic 5-HT(1A) receptor signaling leading to nuclear factor-kappaB (NF-kappaB) activation appears to be critical for cell survival. Adenylyl cyclase and protein kinase A (AC/PKA) are effectors of the 5-HT(1A) receptor that are inhibited by Galpha(i) subunits. Conversely, Gbetagamma(i) subunits downstream from the 5-HT(1A) receptor participate in the activation of extracellular signal-regulated kinases (ERK1/2), phosphatidylinositol 3-kinase (PI3K), Akt, and NF-kappaB. To model the contribution of pro- and antiapoptotic signaling cascades downstream of activated 5-HT(1A) receptor in cell survival, Chinese hamster ovarian (CHO) cells were employed that exogenously overexpress 5-HT(1A) receptors. Stimulation with the 5-HT(1A) receptor agonist 8-OH-DPAT and pharmacological agonists of AC induced PKA and protein phosphatase 2A (PP2A) activity, which in turn inhibited: Akt activity, IkappaBalpha degradation, nuclear translocation of NF-kappaB, and expression of X-linked inhibitor of apoptosis protein (XIAP/BIRC4). Pharmacological inhibition of PP2A with calyculin A potentiated Akt activity while attenuating ERK1/2 signaling via increased inhibitory phosphorylation of Raf (pSer259). In contrast, increased cAMP levels enhanced Bax translocation to the mitochondria, resulting in the release of cytochrome c, caspase-3 activation, and apoptosis induction. Our data suggest a central role of cAMP/PKA-dependent PP2A in shifting the homeostasis of intracellular signaling downstream of activated 5-HT(1A) receptor toward cell death in biological systems linked to neuropsychiatric disorders. (c) 2008 Wiley-Liss, Inc
— id: 78905, year: 2008, vol: 86, page: 2326, stat: Journal Article,

Astrocyte elevated gene-1 activates cell survival pathways through PI3K-Akt signaling
Lee, S-G; Su, Z-Z; Emdad, L; Sarkar, D; Franke, T F; Fisher, P B
2008 Feb 14;27(8):1114-1121, Oncogene
Astrocyte elevated gene-1 (AEG-1) displays oncogenic properties. Its expression is elevated in diverse neoplastic states and it cooperates with Ha-ras to promote cellular transformation. Overexpression of AEG-1 augments invasion and anchorage-independent growth of transformed cells, while AEG-1 siRNA inhibits Ha-ras-mediated colony formation, supporting a potential functional role in tumorigenesis. Additionally, oncogenic Ha-ras induces AEG-1 expression through the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. In the present study, we investigated whether AEG-1 could induce serum-independent cell growth, another property of oncogenes. Overexpression of AEG-1 inhibited serum starvation-induced apoptosis through activation of PI3K-Akt signaling, one of the effector pathways induced by activated Ras. AEG-1 also affected the phosphorylation state of Akt substrates that are implicated in apoptosis suppression, including glycogen synthase kinase 3beta, c-Myc, murine double minute 2, p53, p21/mda-6 and Bad. Additionally, AEG-1 blocked the activity of serum starvation-induced caspases. Taken together, these observations provide evidence that AEG-1 is an oncogene cooperating with Ha-ras as well as functioning as a downstream target gene of Ha-ras and may perform a central role in Ha-ras-mediated carcinogenesis. Activation of survival pathways may be one mechanism by which AEG-1 exerts its oncogenic properties
— id: 75862, year: 2008, vol: 27, page: 1114, stat: Journal Article,

Akt-interacting proteins: attractive opposites. focus on "Carboxy-terminal modulator protein induces Akt phosphorylation and activation, thereby enhancing antiapoptotic, glycogen synthetic, and glucose uptake pathways"
Franke, Thomas F
2007 Dec;293(6):C1768-C1770, American journal of physiology. Cell physiology
— id: 75987, year: 2007, vol: 293, page: C1768, stat: Journal Article,

Pl3K, Akt and PTEN
Franke TF; Berwick DC
Signalling pathways in liver diseases Berlin : Springer, 2005,
— id: 4636, year: 2005, vol: , page: 239, stat: Chapter,

Roles of extracellular signal-regulated kinase and Akt signaling in coordinating nuclear transcription factor-kappaB-dependent cell survival after serotonin 1A receptor activation
Hsiung, Shu-chi; Tamir, Hadassah; Franke, Thomas F; Liu, Kuo-peing
2005 Dec;95(6):1653-1666, Journal of neurochemistry
To investigate the functional consequences of cross-talk between multiple effectors of serotonin (5-HT) 1A receptor, we employed transfected Chinese hamster ovary cells. Activation of 5-HT 1A receptor stimulated extracellular signal-regulated kinase (ERK)1/2, Akt and nuclear transcription factor-kappaB (NF-kappaB). Stimulation of cells with 5-HT 1A receptor agonist induced a rapid but transient ERK1/2 phosphorylation followed by increased phosphorylation of Akt. Elevated Akt activity in turn suppressed Raf activity and induced a decline in ERK activation. The activation of ERK and Akt downstream of 5-HT 1A receptor was sensitive to inhibitors of Ras, Raf and phosphatidylinositol 3-kinase (PI3K). Stimulation of 5-HT 1A receptor also resulted in activation of NF-kappaB through a decrease in inhibitor of nuclear transcription factor-kappaB. In support of the importance of 5-HT 1A receptor signaling for cell survival, inhibition of NF-kappaB facilitated caspase 3 activation and cleavage of poly (ADP-ribose) polymerase, while treatment of cells with agonist inhibited caspase 3, DNA fragmentation and cell death. Both agonist-dependent NF-kappaB activation and cell survival were decreased by Akt Inhibitor II or by overexpression of dominant-negative Akt. These findings suggest a role for 5-HT 1A receptor signaling in the Ras/Raf-dependent regulation of multiple intracellular signaling pathways that include ERK and PI3K/Akt. Of these, only PI3K/Akt and NF-kappaB activation were required for 5-HT 1A receptor-dependent cell survival, implying that the relative distribution of signals between competing transduction pathways determines the functional outcome of 5-HT 1A receptor activation
— id: 74752, year: 2005, vol: 95, page: 1653, stat: Journal Article,

PI3K/Akt and apoptosis: size matters
Franke, Thomas F; Hornik, Christoph P; Segev, Lisa; Shostak, Grigoriy A; Sugimoto, Chizuru
2003 Dec 8;22(56):8983-8998, Oncogene
Recent research has examined Akt and Akt-related serine-threonine kinases in signaling cascades that regulate cell survival and are important in the pathogenesis of degenerative diseases and in cancer. We seek to recapitulate the research that has helped to define the current understanding of the role of the Akt pathway under normal and pathologic conditions, also in view of genetic models of Akt function. In particular, we will evaluate the mechanisms of Akt regulation and the role of Akt substrates in Akt-dependent biologic responses in the decisions of cell death and cell survival. Here, we hope to establish the mechanisms of apoptosis suppression by Akt kinase as a framework for a more general understanding of growth factor-dependent regulation of cell survival
— id: 74721, year: 2003, vol: 22, page: 8983, stat: Journal Article,

Calcium receptor-induced serotonin secretion by parafollicular cells: role of phosphatidylinositol 3-kinase-dependent signal transduction pathways
Liu, Kuo-peing; Russo, Andrew F; Hsiung, Shu-chi; Adlersberg, Mella; Franke, Thomas F; Gershon, Michael D; Tamir, Hadassah
2003 Mar 15;23(6):2049-2057, Journal of neuroscience
Elevation of extracellular Ca2+ (increase[Ca2+]e) stimulates the Ca2+ receptor (CaR) to induce secretion of 5-hydroxytryptamine (5-HT) from the calcium-sensing parafollicular (PF) cells. The CaR has been reported to couple to Galpha(q) with subsequent activation of protein kinase C-gamma (PKCgamma). We have identified a parallel transduction pathway in primary cultures of sheep PF cells by using a combinatorial approach in which we expressed adenoviral-encoded dominant-negative signaling proteins and performed in vitro kinase assays. The role of the CaR was established by expression of a dominant-negative CaR that eliminated calcium-induced 5-HT secretion but not secretion in response to KCl or phorbol esters. The calcium-induced secretion was inhibited by a dominant-negative p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3-K). PI3-K activity was also assayed using isoform-specific antibodies. The activity of p85/p110beta (PI3-Kbeta) immunocomplexes was elevated by increase[Ca2+]e and activated by Gbetagamma subunits. In addition, secretion of 5-HT was antagonized by the expression of a minigene encoding a peptide scavenger of Gbetagamma subunits (C-terminal fragment peptide of bovine beta-adrenergic receptor kinase). One target of PI3-K activity is phosphoinositide-dependent kinase-1 (PDK1), which in turn activated PKCzeta. Expression of a dominant-negative PKCzeta in PF cells reduced 5-HT secretion. Together, these observations establish that increase[Ca2+]e evokes 5-HT secretion from PF cells by stimulating both Galpha(q)- and Gbetagamma-signaling pathways downstream of the CaR. The betagamma cascade subsequently activates PI3-Kbeta-dependent signaling that is coupled to PDK1 and the downstream effector PKCzeta, and results in an increase in 5-HT release
— id: 74709, year: 2003, vol: 23, page: 2049, stat: Journal Article,

Roles of AKT substrates in caspase regulation
Sugimoto, C; Shostak, GA; Franke, TF
2003 ;9(16):6157S-6158S, Clinical cancer research
— id: 75990, year: 2003, vol: 9, page: 6157S, stat: Journal Article,

Epidermal growth factor receptor-dependent, NF-kappaB-independent activation of the phosphatidylinositol 3-kinase/Akt pathway inhibits ultraviolet irradiation-induced caspases-3, -8, and -9 in human keratinocytes
Wang, Hui Qin; Quan, Taihao; He, Tianyuan; Franke, Thomas F; Voorhees, John J; Fisher, Gary J
2003 Nov 14;278(46):45737-45745, Journal of biological chemistry
Both phosphatidylinositol 3-kinase (PI3K)/Akt and NF-kappaB pathways function to promote cellular survival following stress. Recent evidence indicates that the anti-apoptotic activity of these two pathways may be functionally dependent. Ultraviolet (UV) irradiation causes oxidative stress, which can lead to apoptotic cell death. Human skin cells (keratinocytes) are commonly exposed to UV irradiation from the sun. We have investigated activation of the PI3K/Akt and NF-kappaB pathways and their roles in protecting human keratinocytes (KCs) from UV irradiation-induced apoptosis. This activation of PI3K preceded increased levels (3-fold) of active/phosphorylated Akt. UV (50 mJ/cm2 from UVB source) irradiation caused rapid recruitment of PI3K to the epidermal growth factor receptor (EGFR). Pretreatment of KCs with EGFR inhibitor PD169540 abolished UV-induced Akt activation/phosphorylation, as did the PI3K inhibitors LY294002 or wortmannin. This inhibition of Akt activation was associated with a 3-4-fold increase of UV-induced apoptosis, as measured by flow cytometry and DNA fragmentation ELISA. In contrast to Akt, UV irradiation did not detectably increase nuclear localization of NF-kappaB, indicating that it was not strongly activated. Consistent with this observation, interference with NF-kappaB activation by adenovirus-mediated overexpression of dominant negative IKK-beta or IkappaB-alpha did not increase UV-induced apoptosis. However, adenovirus-mediated overexpression of constitutively active Akt completely blocked UV-induced apoptosis observed with PI3K inhibition by LY294002, whereas adenovirus mediated overexpression of dominant negative Akt increased UV-induced apoptosis by 2-fold. Inhibition of UV-induced activation of Akt increased release of mitochondrial cytochrome c 3.5-fold, and caused appearance of active forms of caspase-9, caspase-8, and caspase-3. Constitutively active Akt abolished UV-induced cytochrome c release and activation of caspases-9, -8, and -3. These data demonstrate that PI3K/Akt is essential for protecting human KCs against UV-induced apoptosis, whereas NF-kappaB pathway provides little, if any, protective role
— id: 74718, year: 2003, vol: 278, page: 45737, stat: Journal Article,

Survival signalling by phosphorylation: Pl3K/Akt sets the stage
Franke TF
Apoptosis : the molecular biology of programmed cell death Oxford UK: Oxford University Press, 2002,
— id: 4635, year: 2002, vol: , page: 235, stat: Chapter,

Determinants of AKT-dependent resistance to postmitochondrial apoptosis induction
Franke, T
2002 ;38(18):S166-S166, European journal of cancer
— id: 75992, year: 2002, vol: 38, page: S166, stat: Journal Article,

Role of the AKT kinase in expansion of multiple myeloma clones: effects on cytokine-dependent proliferative and survival responses
Hsu, Jung-hsin; Shi, Yijiang; Hu, Liping; Fisher, Myrna; Franke, Thomas F; Lichtenstein, Alan
2002 Feb 21;21(9):1391-1400, Oncogene
IL-6 is an established growth factor for multiple myeloma tumor cells, stimulating proliferative and survival responses. Recent work indicates that IL-6 can activate the AKT kinase in myeloma cells. Thus, to test a potential role for AKT in IL-6-induced cellular responses, we transfected myeloma cell lines with an active 'E40K' or dominant negative'PH AKT construct using an adenoviral vector. Transfection of the E40K into myeloma cells resulted in enhanced tumor cell growth and expression of the PH dominant negative AKT resulted in both inhibition of the IL-6-dependent proliferative response and a decrease in S phase distribution. While transfection of E40K protected myeloma cells from dexamethasone-induced apoptosis, the dominant negative PH had no effect on the ability of IL-6 to protect these cells from dexamethasone. These results clearly demonstrate that AKT activation is critical for the IL-6 proliferative response. In addition, although the level of AKT activation can regulate sensitivity to dexamethasone-induced apoptosis, additional cytokine-induced AKT-independent pathways can mediate IL-6 protection against dexamethasone. DOI: 10.1038/sj/onc/1205194
— id: 74693, year: 2002, vol: 21, page: 1391, stat: Journal Article,

Activation of ERK, controlled by Rac1 and Cdc42 via Akt, is required for anoikis
Rul, Wilfrid; Zugasti, Olivier; Roux, Pierre; Peyssonnaux, Carole; Eychene, Alain; Franke, Thomas F; Lenormand, Philippe; Fort, Philippe; Hibner, Ursula
2002 Nov;973:145-148, Annals of the New York Academy of Sciences
We have recently reported that two Rho family GTPases, Rac1 and Cdc42, are intimately involved in the control of cell survival of murine fibroblasts linked to adherence to the extracellular matrix. Inhibition of either Rac1 or Cdc42 signaling in adherent cells mimics the loss of anchorage and efficiently induces apoptosis in both immortalized and primary cells. In both cases cell death is dependent on the wild-type p53 tumor suppressor and is accompanied by activation of endogenous p53. Here, we describe that the inhibition of Rac1 or Cdc42 signaling leads to MAPK ERK activation via a pathway involving PI(3)K, Akt, Raf, and MEK, but not Ras. The moderate level of ERK activation that accompanies anoikis is an essential component of proapoptotic signaling; whereas sustained, high-intensity ERK signaling promotes survival in the same experimental system
— id: 74703, year: 2002, vol: 973, page: 145, stat: Journal Article,

Akt/protein kinase B promotes organ growth in transgenic mice
Shioi, Tetsuo; McMullen, Julie R; Kang, Peter M; Douglas, Pamela S; Obata, Toshiyuki; Franke, Thomas F; Cantley, Lewis C; Izumo, Seigo
2002 Apr;22(8):2799-2809, Molecular & cellular biology
One of the least-understood areas in biology is the determination of the size of animals and their organs. In Drosophila, components of the insulin receptor phosphoinositide 3-kinase (PI3K) pathway determine body, organ, and cell size. Several biochemical studies have suggested that Akt/protein kinase B is one of the important downstream targets of PI3K. To examine the role of Akt in the regulation of organ size in mammals, we have generated and characterized transgenic mice expressing constitutively active Akt (caAkt) or kinase-deficient Akt (kdAkt) specifically in the heart. The heart weight of caAkt transgenic mice was increased 2.0-fold compared with that of nontransgenic mice. The increase in heart size was associated with a comparable increase in myocyte cell size in caAkt mice. The kdAkt mutant protein attenuated the constitutively active PI3K-induced overgrowth of the heart, and the caAkt mutant protein circumvented cardiac growth retardation induced by a kinase-deficient PI3K mutant protein. Rapamycin attenuated caAkt-induced overgrowth of the heart, suggesting that the mammalian target of rapamycin (mTOR) or effectors of mTOR mediated caAkt-induced heart growth. In conclusion, Akt is sufficient to induce a marked increase in heart size and is likely to be one of the effectors of the PI3K pathway in mediating heart growth
— id: 74694, year: 2002, vol: 22, page: 2799, stat: Journal Article,

Characterization of a novel isoform of caspase-9 that inhibits apoptosis
Angelastro, J M; Moon, N Y; Liu, D X; Yang, A S; Greene, L A; Franke, T F
2001 Apr 13;276(15):12190-12200, Journal of biological chemistry
We have identified a novel isoform of rat caspase-9 in which the C terminus of full-length caspase-9 is replaced with an alternative peptide sequence. Casp-9-CTD (where CTD is carboxyl-terminal divergent) is expressed in multiple tissues, with the relative highest expression observed in ovary and heart. Casp-9-CTD was found primarily in the cytoplasm and was not detected in the nucleus. Structural predictions suggest that in contrast to full-length caspase-9, casp-9-CTD will not be processed. Our model is supported by reduced protease activity of casp-9-CTD preparations in vitro and by the lack of detectable processing of casp-9-CTD proenzyme or the induction of cell death following transfection into cells. Both neuronal and non-neuronal cell types transfected with casp-9-CTD were resistant to death evoked by trophic factor deprivation or DNA damage. In addition, cytosolic lysates prepared from cells permanently expressing exogenous casp-9-CTD were resistant to caspase induction by cytochrome c in reconstitution assays. Taken together, our observations indicate that casp-9-CTD acts as a dominant-negative variant. Its expression in various tissues indicates a physiological role in regulating cell death
— id: 75866, year: 2001, vol: 276, page: 12190, stat: Journal Article,

Overexpression of Akt inhibits NGF-induced growth arrest and neuronal differentiation of PC12 cells
Bang, O S; Park, E K; Yang, S I; Lee, S R; Franke, T F; Kang, S S
2001 Jan;114(Pt 1):81-88, Journal of cell science
To investigate the role of Akt in nerve growth factor (NGF)-induced neuronal differentiation, PC12 cells ectopically expressing wild-type or dominant-inhibitory forms of Akt were analyzed. NGF-induced neurite outgrowth was greatly accelerated in cells expressing dominant-inhibitory Akt, compared to parental PC12 cells, but was almost completely blocked in cells expressing wild-type Akt. Since neuronal differentiation requires an arrest of cell growth, several aspects of cell growth of the different cell lines were compared. Cells expressing wild-type Akt were not susceptible to the growth-arresting effect of NGF, whereas parental PC12 cells and notably cells expressing mutant Akt were so affected. Accompanying this, the expressions of CDKs and p21(WAF1) were down- and up-regulated, respectively, in both parental PC12 cells and cells expressing mutant Akt. When treated with some growth arrest-inducing agents such as sodium nitroprusside, forskolin and butyrolactone I, cells expressing wild-type Akt regained their responsiveness to the effects of NGF on differentiation. In summary, our results indicate that Akt overrides the growth-arresting effect of NGF and thereby, negatively regulates neuronal differentiation
— id: 75868, year: 2001, vol: 114, page: 81, stat: Journal Article,

The AKT kinase is activated in multiple myeloma tumor cells
Hsu, J; Shi, Y; Krajewski, S; Renner, S; Fisher, M; Reed, J C; Franke, T F; Lichtenstein, A
2001 Nov 1;98(9):2853-2855, Blood
Immunohistochemistry (IHC) was performed on archived bone marrow (BM) with a phosphospecific anti-AKT antibody. IHC on 26 BM biopsies from patients with multiple myeloma (MM) demonstrated phospho-AKT staining of malignant plasma cells in a cell membrane-specific pattern, whereas nonmalignant hematopoietic cells did not stain. Preabsorption of the antibody with phosphorylated AKT peptide, but not nonphosphorylated peptide, abrogated staining. Frequency of plasma cell staining in BMs of patients with stage I or smoldering MM was significantly less than that of stage III MM marrows. Plasma cells in 10 patients with monoclonal gammopathy of undetermined significance were not stained by the antibody. To investigate the significance of AKT activation, 2 cell lines initiated from cultures of primary MM cells were also studied. Both demonstrated constitutive AKT activation. Interruption of AKT activation and activity, achieved by either exposure to wortmannin or by ectopic expression of a dominant negative AKT mutant, resulted in inhibition of MM cell growth in vitro. These results indicate that activation of the AKT kinase is a characteristic of MM cells and suggest that AKT activity is important for MM cell expansion
— id: 75863, year: 2001, vol: 98, page: 2853, 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,

Akt activation preserves cardiac function and prevents injury after transient cardiac ischemia in vivo
Matsui, T; Tao, J; del Monte, F; Lee, K H; Li, L; Picard, M; Force, T L; Franke, T F; Hajjar, R J; Rosenzweig, A
2001 Jul 17;104(3):330-335, Circulation
BACKGROUND: The serine-threonine kinase Akt is activated by several ligand-receptor systems previously shown to be cardioprotective. Akt activation reduces cardiomyocyte apoptosis in models of transient ischemia. Its role in cardiac dysfunction or infarction, however, remains unclear. METHODS AND RESULTS: We examined the effects of a constitutively active Akt mutant (myr-Akt) in a rat model of cardiac ischemia-reperfusion injury. In vivo gene transfer of myr-Akt reduced infarct size by 64% and the number of apoptotic cells by 84% (P<0.005 for each). Ischemia-reperfusion injury decreased regional cardiac wall thickening as well as the maximal rate of left ventricular pressure rise and fall (+dP/dt and -dP/dt). Akt activation restored regional wall thickening and +dP/dt and -dP/dt to levels seen in sham-operated rats. To better understand this benefit, we examined the effects of myr-Akt on hypoxic cardiomyocyte dysfunction in vitro. myr-Akt prevented hypoxia-induced abnormalities in cardiomyocyte calcium transients and shortening. Akt activation also enhanced sarcolemmal expression of Glut-4 in vivo and increased glucose uptake in vitro to the level seen with insulin treatment. CONCLUSIONS: Akt activation exerts a powerful cardioprotective effect after transient ischemia that probably reflects its ability to both inhibit cardiomyocyte death and improve function of surviving cardiomyocytes. Akt may represent an important nodal target for therapy in ischemic and other heart disease
— id: 75865, year: 2001, vol: 104, page: 330, stat: Journal Article,

Raf-MEK-Erk cascade in anoikis is controlled by Rac1 and Cdc42 via Akt
Zugasti, O; Rul, W; Roux, P; Peyssonnaux, C; Eychene, A; Franke, T F; Fort, P; Hibner, U
2001 Oct;21(19):6706-6717, Molecular & cellular biology
Signals from the extracellular matrix are essential for the survival of many cell types. Dominant-negative mutants of two members of Rho family GTPases, Rac1 and Cdc42, mimic the loss of anchorage in primary mouse fibroblasts and are potent inducers of apoptosis. This pathway of cell death requires the activation of both the p53 tumor suppressor and the extracellular signal-regulated mitogen-activated protein kinases (Erks). Here we characterize the proapoptotic Erk signal and show that it differs from the classically observed survival-promoting one by the intensity of the kinase activation. The disappearance of the GTP-bound forms of Rac1 and Cdc42 gives rise to proapoptotic, moderate activation of the Raf-MEK-Erk cascade via a signaling pathway involving the kinases phosphatidlyinositol 3-kinase and Akt. Moreover, concomitant activation of p53 and inhibition of Akt are both necessary and sufficient to signal anoikis in primary fibroblasts. Our data demonstrate that the GTPases of the Rho family control three major components of cellular signal transduction, namely, p53, Akt, and Erks, which collaborate in the induction of apoptosis due to the loss of anchorage
— id: 75864, year: 2001, vol: 21, page: 6706, stat: Journal Article,

IGF-I promotes Schwann cell motility and survival via activation of Akt
Cheng, H L; Steinway, M; Delaney, C L; Franke, T F; Feldman, E L
2000 Dec 22;170(1-2):211-215, Molecular & cellular endocrinology
We previously reported insulin-like growth factor-I (IGF-I) promotes Schwann cell (SC) motility and rescues SC from apoptosis induced by serum deprivation. This effect is mediated by phosphatidylinositol-3 (PI-3) kinase. In the current study, we examined the role of Akt, a downstream kinase of PI-3K, in SC motility and IGF-I mediated protection from apoptosis. IGF-I induces Akt phosphorylation at Ser473, an event which may be blocked by pretreatment with a PI-3K inhibitor, LY294002. In dominant negative K179M Akt (K179M) transfected SC, however, Akt is not activated in response to IGF-I. In addition, IGF-I is unable to promote SC motility and survival in K179M SC. These results suggest a critical role for Akt in IGF-I mediated motility and survival in SC
— id: 75867, year: 2000, vol: 170, page: 211, stat: Journal Article,

Assays for Akt
Franke, T F
2000 ;322:400-410, Methods in enzymology
An increasing number of publications have underscored the importance of the serine/threonine kinase Akt in the regulation of cell survival, proliferation, and insulin-dependent metabolic cell responses. Critical to the understanding of Akt signaling in cells are experimental methods that assess its activation and phosphorylation state. In this chapter, we evaluate the most commonly used techniques to examine Akt activity. Immunocomplex kinase assays that utilize Akt-specific substrates are described, as is the use of phosphospecific antibodies directed against Akt phosphorylation sites. Furthermore, we introduce coupled enzyme assays that indirectly measure the activity of Akt by examining the activity of Akt substrates
— id: 75870, year: 2000, vol: 322, page: 400, stat: Journal Article,

Divergent regulation of Akt1 and Akt2 isoforms in insulin target tissues of obese Zucker rats
Kim, Y B; Peroni, O D; Franke, T F; Kahn, B B
2000 May;49(5):847-856, Diabetes
To determine whether impaired Akt (protein kinase B or rac) activation contributes to insulin resistance in vivo, we examined the expression, phosphorylation, and kinase activities of Akt1 and Akt2 isoforms in insulin target tissues of insulin-resistant obese Zucker rats. In lean rats, insulin (10 U/kg i.v. x 2.5 min) stimulated Akt1 activity 6.2-, 8.8-, and 4.4-fold and Akt2 activity 5.4-, 9.3-, and 1.8-fold in muscle, liver, and adipose tissue, respectively. In obese rats, insulin-stimulated Akt1 activity decreased 30% in muscle and 21% in adipose tissue but increased 37% in liver compared with lean littermates. Insulin-stimulated Akt2 activity decreased 29% in muscle and 37% in liver but increased 24% in adipose tissue. Akt2 protein levels were reduced 56% in muscle and 35% in liver of obese rats, but Akt1 expression was unaltered. Phosphoinositide 3-kinase (PI3K) activity associated with insulin receptor substrate (IRS)-1 or phosphotyrosine was reduced 67-86% in tissues of obese rats because of lower IRS-1 protein levels and reduced insulin receptor and IRS-1 phosphorylation. In adipose tissue of obese rats, in spite of an 86% reduction in insulin-stimulated PI3K activity, activation of Akt2 was increased. Maximal insulin-stimulated (100 nmol/l) glucose transport was reduced 70% in isolated adipocytes, with a rightward shift in the insulin dose response for transport and for Akt1 stimulation but normal sensitivity for Akt2. These findings suggest that PI3K-dependent effects on glucose transport in adipocytes are not mediated primarily by Akt2. Akt1 and Akt2 activations by insulin have a similar time course and are maximal by 2.5 min in adipocytes of both lean and obese rats. We conclude that 1) activation of Akt1 and Akt2 in vivo is much less impaired than activation of PI3K in this insulin-resistant state, and 2) the mechanisms for divergent alterations in insulin action on Akt1 and Akt2 activities in tissues of insulin-resistant obese rats involve tissue- and isoform-specific changes in both expression and activation
— id: 75871, year: 2000, vol: 49, page: 847, stat: Journal Article,

Caspase Phosphorylation, cell death, and species variability
Reed JC; Cardone MH; Roy N; Stennicke HR; Salvesen GS; Franke T; Stanbridge E
2000 ;287:1363a-1363a, Science
— id: 76005, year: 2000, vol: 287, page: 1363a, stat: Journal Article,

Epidermal growth factor receptor-dependent Akt activation by oxidative stress enhances cell survival
Wang, X; McCullough, K D; Franke, T F; Holbrook, N J
2000 May 12;275(19):14624-14631, Journal of biological chemistry
The serine/threonine kinase Akt (also known as protein kinase B) is activated in response to various stimuli by a mechanism involving phosphoinositide 3-kinase (PI3-K). Akt provides a survival signal that protects cells from apoptosis induced by growth factor withdrawal, but its function in other forms of stress is less clear. Here we investigated the role of PI3-K/Akt during the cellular response to oxidant injury. H(2)O(2) treatment elevated Akt activity in multiple cell types in a time- (5-30 min) and dose (400 microM-2 mm)-dependent manner. Expression of a dominant negative mutant of p85 (regulatory component of PI3-K) and treatment with inhibitors of PI3-K (wortmannin and LY294002) prevented H(2)O(2)-induced Akt activation. Akt activation by H(2)O(2) also depended on epidermal growth factor receptor (EGFR) signaling; H(2)O(2) treatment led to EGFR phosphorylation, and inhibition of EGFR activation prevented Akt activation by H(2)O(2). As H(2)O(2) causes apoptosis of HeLa cells, we investigated whether alterations of PI3-K/Akt signaling would affect this response. Wortmannin and LY294002 treatment significantly enhanced H(2)O(2)-induced apoptosis, whereas expression of exogenous myristoylated Akt (an activated form) inhibited cell death. Constitutive expression of v-Akt likewise enhanced survival of H(2)O(2)-treated NIH3T3 cells. These results suggest that H(2)O(2) activates Akt via an EGFR/PI3-K-dependent pathway and that elevated Akt activity confers protection against oxidative stress-induced apoptosis
— id: 75872, year: 2000, vol: 275, page: 14624, stat: Journal Article,

Akt-dependent potentiation of L channels by insulin-like growth factor-1 is required for neuronal survival
Blair, L A; Bence-Hanulec, K K; Mehta, S; Franke, T; Kaplan, D; Marshall, J
1999 Mar 15;19(6):1940-1951, Journal of neuroscience
The insulin-like growth factor-1 (IGF-1)/receptor tyrosine kinase recently has been shown to mediate neuronal survival and potentiate the activity of specific calcium channel subtypes; survival requires Akt, a serine/threonine kinase. We demonstrate here that Akt mediates the IGF-1-induced potentiation of L channel currents, but not that of N channels. Transient expression of wild-type, dominant-negative, and constitutively active forms of Akt in cerebellar granule neurons causes, respectively, no change in IGF-1/L channel potentiation, complete inhibition of potentiation, and a dramatic increase in basal L currents accompanied by the loss of ability to induce further increases. In no case is the IGF-1 potentiation of N currents affected. We additionally find that IGF-1 partially mediates granule neuron survival via L channel activity and that Akt-dependent L channel modulation is a necessary component. Interestingly, very brief exposure (1 min) to IGF-1 triggers nearly complete survival and requires L channel activity. These results strongly suggest that neuronal receptor tyrosine kinases can control long-term calcium-dependent processes via the rapid control of voltage-sensitive channels
— id: 75988, year: 1999, vol: 19, page: 1940, stat: Journal Article,

A difficult AKT to follow
Franke TF
1999 ;5:2-7, Neural notes
— id: 76006, year: 1999, vol: 5, page: 2, stat: Journal Article,

Regulation of endothelium-derived nitric oxide production by the protein kinase Akt
Fulton, D; Gratton, J P; McCabe, T J; Fontana, J; Fujio, Y; Walsh, K; Franke, T F; Papapetropoulos, A; Sessa, W C
1999 Jun 10;399(6736):597-601, Nature
Endothelial nitric oxide synthase (eNOS) is the nitric oxide synthase isoform responsible for maintaining systemic blood pressure, vascular remodelling and angiogenesis. eNOS is phosphorylated in response to various forms of cellular stimulation, but the role of phosphorylation in the regulation of nitric oxide (NO) production and the kinase(s) responsible are not known. Here we show that the serine/threonine protein kinase Akt (protein kinase B) can directly phosphorylate eNOS on serine 1179 and activate the enzyme, leading to NO production, whereas mutant eNOS (S1179A) is resistant to phosphorylation and activation by Akt. Moreover, using adenovirus-mediated gene transfer, activated Akt increases basal NO release from endothelial cells, and activation-deficient Akt attenuates NO production stimulated by vascular endothelial growth factor. Thus, eNOS is a newly described Akt substrate linking signal transduction by Akt to the release of the gaseous second messenger NO
— id: 75876, year: 1999, vol: 399, page: 597, stat: Journal Article,

Macrophage colony-stimulating factor promotes cell survival through Akt/protein kinase B
Kelley, T W; Graham, M M; Doseff, A I; Pomerantz, R W; Lau, S M; Ostrowski, M C; Franke, T F; Marsh, C B
1999 Sep 10;274(37):26393-26398, Journal of biological chemistry
The signaling pathways activated by the macrophage colony-stimulating factor (M-CSF) to promote survival of monocyte and macrophage lineage cells are not well established. In an effort to elucidate these pathways, we have used two cell types responsive to M-CSF: NIH 3T3 fibroblasts genetically engineered to express human M-CSF receptors (3T3-FMS cells) and human monocytes. M-CSF treatment induced M-CSF receptor tyrosine phosphorylation and recruitment of the p85 subunit of phosphatidylinositol 3-kinase (PI3K) to these receptors. These M-CSF receptor events correlated with activation of the serine/threonine kinase Akt. To clarify that PI3K products activate Akt in response to M-CSF, NIH 3T3 fibroblasts expressing mutant human M-CSF receptors (3T3-FMS(Y809F)) that fail to activate Ras in response to M-CSF also exhibit increased Akt kinase activity in response to M-CSF challenge. Furthermore, Akt appears to be the primary regulator of survival in 3T3-FMS cells, as transfection of genes encoding dominant-negative Akt isoforms into these fibroblasts blocked M-CSF-induced survival. In normal human monocytes, M-CSF increased the levels of tyrosine-phosphorylated proteins and induced Akt activation in a PI3K-dependent manner. The PI3K inhibitor LY294002 blocked M-CSF-mediated monocyte survival, an effect that was partially restored by caspase-9 inhibitors. These data suggest that M-CSF may induce cell survival through Akt-induced suppression of caspase-9 activation
— id: 75875, year: 1999, vol: 274, page: 26393, stat: Journal Article,

Divergent regulation of Akt1 and Akt2 in insulin target tissues of insulin resistant obese Zucker rats
Kim, YB; Peroni, OD; Franke, TF; Kahn, BB
1999 ;48(5):A273-A273, Diabetes
— id: 76003, year: 1999, vol: 48, page: A273, stat: Journal Article,

Protein kinase C-alpha overexpression stimulates Akt activity and suppresses apoptosis induced by interleukin 3 withdrawal
Li, W; Zhang, J; Flechner, L; Hyun, T; Yam, A; Franke, T F; Pierce, J H
1999 Nov 11;18(47):6564-6572, Oncogene
To investigate the role of protein kinase C (PKC) in apoptotic signaling induced by cytokine withdrawal, we expressed PKC-alpha, -delta and -epsilon individually in the 32D myeloid progenitor cells. The parental and PKC-delta- and PKC-epsilon-transfected 32D cells underwent apoptosis within 24 h in the absence of interleukin 3. In contrast, expression of PKC-alpha inhibited the onset of apoptosis as determined by genomic DNA fragmentation and flow cytometric analysis. Correlating with the inhibition of apoptosis, PKC-alpha transfectants exhibited increased activity of the endogenous Akt serine/threonine kinase. Furthermore, PKC-alpha, but not PKC-delta or -epsilon, specifically activated overexpressed Akt. PKC-alpha-induced Akt activity was partially dependent on phosphoinositol 3' kinase (PI 3'K) since a PI 3'K inhibitor was able to suppress PKC-alpha-induced Akt activation. Both basal and interleukin 3-stimulated phosphorylation of Akt on serine 473 was enhanced in the PKC-alpha and Akt contransfectants. Coexpression of wild type Akt and PKC-alpha resulted in greater suppression of apoptosis than PKC-alpha expression alone. Together, our results demonstrate that suppression of apoptosis by PKC-alpha correlates with its ability of activating endogenous Akt. Furthermore, activation of overexpressed Akt by PKC-alpha is consistent with their synergistic effect on suppressing apoptosis, providing the strong evidence of cross talk between Akt and PKC-alpha
— id: 75873, year: 1999, vol: 18, page: 6564, stat: Journal Article,

Protein kinase C-alpha overexpression stimulates Akt activity and suppresses apoptosis induced by interleukin 3 withdrawal
Li, WQ; Zhang, IC; Flechner, L; Hyun, T; Yarn, A; Franke, TF; Pierce, JH
1999 ;94(10):482A-482A, Blood
— id: 76002, year: 1999, vol: 94, page: 482A, stat: Journal Article,

Adenoviral gene transfer of activated phosphatidylinositol 3'-kinase and Akt inhibits apoptosis of hypoxic cardiomyocytes in vitro
Matsui, T; Li, L; Fukui, Y; Franke, T F; Hajjar, R J; Rosenzweig, A
1999 Dec 7;100(23):2373-2379, Circulation
BACKGROUND: The intracellular signaling pathways that control cardiomyocyte apoptosis have not been fully defined. Because insulin-like growth factor-1 (IGF-1) prevents cardiomyocyte apoptosis, we examined the role of its downstream signaling molecules in an in vitro model of hypoxia-induced cardiomyocyte apoptosis. METHODS AND RESULTS: Treatment of rat neonatal cardiomyocytes with IGF-1 increased activity of both phosphatidylinositol 3' (PI 3)-kinase and its downstream target, Akt (also known as protein kinase B or PKB). Cardiomyocytes were subjected to hypoxia for 24 hours, and apoptosis was assessed by DNA laddering, TUNEL staining, and ELISA for histone-associated DNA fragments. IGF-1 treatment (100 nmol/L) reduced cardiomyocyte apoptosis, and this effect was inhibited by simultaneous treatment with a PI 3-kinase inhibitor. Cardiomyocytes were infected with either a control adenovirus (Ad.EGFP) or adenoviruses carrying constitutively active forms of PI 3-kinase (Ad.BD110) or Akt (Ad. myr-Akt-HA). Ad.BD110 significantly inhibited apoptosis of hypoxic cardiomyocytes compared with Ad.EGFP (61.0+/-4.6% less DNA fragmentation than in Ad.EGFP-infected cells, P<0.0001). Ad. myr-Akt-HA even more dramatically inhibited apoptosis of hypoxic cardiomyocytes (90.9+/-1.4% less DNA fragmentation than in controls, P<0.0001). CONCLUSIONS: IGF-1 activates PI 3-kinase and Akt in cardiomyocytes. Activated PI 3-kinase and Akt are each sufficient to protect hypoxic cardiomyocytes against apoptosis in vitro. Adenoviral gene transfer provides a useful tool for investigating the role of these signaling pathways in cardiomyocyte apoptosis
— id: 75874, year: 1999, vol: 100, page: 2373, stat: Journal Article,

Ca2+-induced apoptosis through calcineurin dephosphorylation of BAD
Wang, H G; Pathan, N; Ethell, I M; Krajewski, S; Yamaguchi, Y; Shibasaki, F; McKeon, F; Bobo, T; Franke, T F; Reed, J C
1999 Apr 9;284(5412):339-343, Science
The Ca2+-activated protein phosphatase calcineurin induces apoptosis, but the mechanism is unknown. Calcineurin was found to dephosphorylate BAD, a pro-apoptotic member of the Bcl-2 family, thus enhancing BAD heterodimerization with Bcl-xL and promoting apoptosis. The Ca2+-induced dephosphorylation of BAD correlated with its dissociation from 14-3-3 in the cytosol and translocation to mitochondria where Bcl-xL resides. In hippocampal neurons, L-glutamate, an inducer of Ca2+ influx and calcineurin activation, triggered mitochondrial targeting of BAD and apoptosis, which were both suppressible by coexpression of a dominant-inhibitory mutant of calcineurin or pharmacological inhibitors of this phosphatase. Thus, a Ca2+-inducible mechanism for apoptosis induction operates by regulating BAD phosphorylation and localization in cells
— id: 75877, year: 1999, vol: 284, page: 339, stat: Journal Article,

Regulation of cell death protease caspase-9 by phosphorylation
Cardone, M H; Roy, N; Stennicke, H R; Salvesen, G S; Franke, T F; Stanbridge, E; Frisch, S; Reed, J C
1998 Nov 13;282(5392):1318-1321, Science
Caspases are intracellular proteases that function as initiators and effectors of apoptosis. The kinase Akt and p21-Ras, an Akt activator, induced phosphorylation of pro-caspase-9 (pro-Casp9) in cells. Cytochrome c-induced proteolytic processing of pro-Casp9 was defective in cytosolic extracts from cells expressing either active Ras or Akt. Akt phosphorylated recombinant Casp9 in vitro on serine-196 and inhibited its protease activity. Mutant pro-Casp9(Ser196Ala) was resistant to Akt-mediated phosphorylation and inhibition in vitro and in cells, resulting in Akt-resistant induction of apoptosis. Thus, caspases can be directly regulated by protein phosphorylation
— id: 75878, year: 1998, vol: 282, page: 1318, stat: Journal Article,

Role of Akt and c-Jun N-terminal kinase 2 in apoptosis induced by interleukin-4 deprivation
Cerezo, A; Martinez-A, C; Lanzarot, D; Fischer, S; Franke, T F; Rebollo, A
1998 Nov;9(11):3107-3118, Molecular biology of the cell
We have shown previously that interleukin-4 (IL-4) protects TS1alphabeta cells from apoptosis, but very little is known about the mechanism by which IL-4 exerts this effect. We found that Akt activity, which is dependent on phosphatidylinositol 3 kinase, is reduced in IL-4-deprived TS1alphabeta cells. Overexpression of wild-type Akt or a constitutively active Akt mutant protects cells from IL-4 deprivation-induced apoptosis. Readdition of IL-4 before the commitment point is able to restore Akt activity. We also show expression and c-Jun N-terminal kinase 2 activation after IL-4 deprivation. Overexpression of the constitutively activated Akt mutant in IL-4-deprived cells correlates with inhibition of c-Jun N-terminal kinase 2 activity. Finally, TS1alphabeta survival is independent of Bcl-2, Bcl-x, or Bax
— id: 75879, year: 1998, vol: 9, page: 3107, stat: Journal Article,

Phosphoinositide 3-kinase regulation of T cell receptor-mediated interleukin-2 gene expression in normal T cells
Eder, A M; Dominguez, L; Franke, T F; Ashwell, J D
1998 Oct 23;273(43):28025-28031, Journal of biological chemistry
Phosphoinositide (PI) 3-kinase has been implicated in T cell receptor (TCR) signaling, either as a positive or a negative regulatory molecule. Here, we show that for normal mouse lymph node T cells, PI 3-kinase activity is required for interleukin-2 (IL-2) production following TCR-mediated activation. Furthermore, in normal T cells, inhibition of PI 3-kinase prevented activation of enzymes in the extracellular signal-regulated protein kinase (ERK) signaling pathway (MEK-1 and ERK-2). Overexpression of a dominant-negative mutant of PI 3-kinase and pharmacological inhibitors of PI 3-kinase prevented transcriptional activation of AP-1 and NF-AT, transcription factors regulated by ERK-2 and pivotal for IL-2 gene expression. Although a constitutively active form of Akt kinase, a downstream mediator of PI 3-kinase function, enhanced TCR-induced IL-2 gene transcription, it could not bypass the requirement for PI 3-kinase activity. Therefore, PI 3-kinase is likely to be involved in signaling for IL-2 production in at least two steps in the TCR-initiated signaling pathway
— id: 75880, year: 1998, vol: 273, page: 28025, stat: Journal Article,

Regulation of neuronal survival by the serine-threonine protein kinase Akt
Dudek, H; Datta, S R; Franke, T F; Birnbaum, M J; Yao, R; Cooper, G M; Segal, R A; Kaplan, D R; Greenberg, M E
1997 Jan 31;275(5300):661-665, Science
A signaling pathway was delineated by which insulin-like growth factor 1 (IGF-1) promotes the survival of cerebellar neurons. IGF-1 activation of phosphoinositide 3-kinase (PI3-K) triggered the activation of two protein kinases, the serine-threonine kinase Akt and the p70 ribosomal protein S6 kinase (p70(S6K)). Experiments with pharmacological inhibitors, as well as expression of wild-type and dominant-inhibitory forms of Akt, demonstrated that Akt but not p70(S6K) mediates PI3-K-dependent survival. These findings suggest that in the developing nervous system, Akt is a critical mediator of growth factor-induced neuronal survival
— id: 75885, year: 1997, vol: 275, page: 661, stat: Journal Article,

Apoptosis. A Bad kinase makes good
Franke, T F; Cantley, L C
1997 Nov 13;390(6656):116-117, Nature
— id: 75881, year: 1997, vol: 390, page: 116, stat: Journal Article,

PI3K: downstream AKTion blocks apoptosis
Franke, T F; Kaplan, D R; Cantley, L C
1997 Feb 21;88(4):435-437, Cell
— id: 75883, year: 1997, vol: 88, page: 435, stat: Journal Article,

Direct regulation of the Akt proto-oncogene product by phosphatidylinositol-3,4-bisphosphate
Franke, T F; Kaplan, D R; Cantley, L C; Toker, A
1997 Jan 31;275(5300):665-668, Science
The regulation of the serine-threonine kinase Akt by lipid products of phosphoinositide 3-kinase (PI 3-kinase) was investigated. Akt activity was found to correlate with the amount of phosphatidylinositol-3,4-bisphosphate (PtdIns-3,4-P2) in vivo, and synthetic PtdIns-3,4-P2 activated Akt both in vitro and in vivo. Binding of PtdIns-3,4-P2 occurred within the Akt pleckstrin homology (PH) domain and facilitated dimerization of Akt. Akt mutated in the PH domain was not activated by PI 3-kinase in vivo or by PtdIns-3, 4-P2 in vitro, and it was impaired in binding to PtdIns-3,4-P2. Examination of the binding to other phosphoinositides revealed that they bound to the Akt PH domain with much lower affinity than did PtdIns-3,4-P2 and failed to increase Akt activity. Thus, Akt is apparently regulated by the direct interaction of PtdIns-3,4-P2 with the Akt PH domain
— id: 75884, year: 1997, vol: 275, page: 665, stat: Journal Article,

Interleukin 3-dependent survival by the Akt protein kinase
Songyang, Z; Baltimore, D; Cantley, L C; Kaplan, D R; Franke, T F
1997 Oct 14;94(21):11345-11350, Proceedings of the National Academy of Sciences of the United States of America
Interleukin 3 (IL-3)-dependent survival of hematopoietic cells is known to rely on the activity of multiple signaling pathways, including a pathway leading to activation of phosphoinositide 3-kinase (PI 3-kinase), and protein kinase Akt is a direct target of PI 3-kinase. We find that Akt kinase activity is rapidly induced by the cytokine IL-3, suggesting a role for Akt in PI 3-kinase-dependent signaling in hematopoetic cells. Dominant-negative mutants of Akt specifically block Akt activation by IL-3 and interfere with IL-3-dependent proliferation. Overexpression of Akt or oncogenic v-akt protects 32D cells from apoptosis induced by IL-3 withdrawal. Apoptosis after IL-3 withdrawal is accelerated by expression of dominant-negative mutants of Akt, indicating that a functional Akt signaling pathway is necessary for cell survival mediated by the cytokine IL-3. Thus Akt appears to be an important mediator of anti-apoptotic signaling in this system
— id: 75882, year: 1997, vol: 94, page: 11345, stat: Journal Article,

Molecular mechanisms of survival and apoptosis in cerebellar neurons
Dudek, H.; Datta, S. R.; Franke, T. F.; Kaplan, D. R.; Segal, R. A.; Greenberg, M. E.
1996 ;22(1-3):563-563, Abstracts (Society for Neuroscience)
— id: 92625, year: 1996, vol: 22, page: 563, stat: Journal Article,

The AKT proto-oncogene in NGF and PDGF signal transduction
Franke, Thomas F.; Dudek, Henryk T.; Toker, Alex; Cantley, Lewis C.; Greenberg, Michael E.; Kaplan, David R.
1996 ;22(1-3):556-556, Abstracts (Society for Neuroscience)
— id: 92626, year: 1996, vol: 22, page: 556, stat: Journal Article,

AH/PH domain-mediated interaction between Akt molecules and its potential role in Akt regulation
Datta, K; Franke, T F; Chan, T O; Makris, A; Yang, S I; Kaplan, D R; Morrison, D K; Golemis, E A; Tsichlis, P N
1995 Apr;15(4):2304-2310, Molecular & cellular biology
The cytoplasmic serine-threonine protein kinase coded for by the c-akt proto-oncogene features a protein kinase C-like catalytic domain and a unique NH2-terminal domain (AH domain). The AH domain is a member of a domain superfamily whose prototype was observed in pleckstrin (pleckstrin homology, or PH, domain). In this communication, we present evidence that the AH/PH domain is a domain of protein-protein interaction which mediates the formation of Akt protein complexes. The interaction between c-akt AH/PH domains is highly specific, as determined by the failure of this domain to bind AKT2. The AH/PH domain-mediated interactions depend on the integrity of the entire domain. Akt molecules with deletions of the NH2-terminal portion (amino acids 11 to 60) and AH/PH constructs with deletions of the C-terminal portion of this domain (amino acids 107 to 147) fail to interact with c-akt. To determine the significance of these findings, we carried out in vitro kinase assays using Akt immunoprecipitates from serum-starved and serum-starved, platelet-derived growth factor-stimulated NIH 3T3 cells. Addition of maltose-binding protein-AH/PH fusion recombinant protein, which is expected to bind Akt, to the immunoprecipitates from serum-starved cells induced the activation of the Akt kinase
— id: 75887, year: 1995, vol: 15, page: 2304, stat: Journal Article,

The protein kinase encoded by the Akt proto-oncogene is a target of the PDGF-activated phosphatidylinositol 3-kinase
Franke, T F; Yang, S I; Chan, T O; Datta, K; Kazlauskas, A; Morrison, D K; Kaplan, D R; Tsichlis, P N
1995 Jun 2;81(5):727-736, Cell
The serine/threonine protein kinase encoded by the Akt proto-oncogene is catalytically inactive in serum-starved primary and immortalized fibroblasts. Here we show that Akt and the Akt-related kinase AKT2 are activated by PDGF. The activation was rapid and specific, and it was abrogated by mutations in the Akt Pleckstrin homology (PH) domain. The Akt activation was also shown to depend on PDGFR beta tyrosines Y740 and Y751, which bind phosphatidylinositol 3-kinase (PI 3-kinase) upon phosphorylation. Moreover, Akt activation was blocked by the PI 3-kinase-specific inhibitor wortmannin and the dominant inhibitory N17Ras. Conversely, Akt activity was induced following the addition of phosphatidylinositol-3-phosphate to Akt immunoprecipitates from serum-starved cells in vitro. These results identify Akt as a novel target of PI 3-kinase and suggest that the Akt PH domain may be a mediator of PI 3-kinase signaling
— id: 75886, year: 1995, vol: 81, page: 727, stat: Journal Article,

The SH2-like Akt homology (AH) domain of c-akt is present in multiple copies in the genome of vertebrate and invertebrate eucaryotes. Cloning and characterization of the Drosophila melanogaster c-akt homolog Dakt1
Franke, T F; Tartof, K D; Tsichlis, P N
1994 Jan;9(1):141-148, Oncogene
The Akt proto-oncogene encodes a serine-threonine protein kinase whose carboxyterminal catalytic domain is closely related to the catalytic domains of all the known members of the protein kinase C (PKC) family. Akt, however, differs from PKC in its N-terminal region which contains a domain related distantly to the SH2 domain of cytoplasmic tyrosine kinases and other signalling proteins, which we have named Akt homology (AH) domain. Low stringency hybridization of a c-akt AH probe to a panel of genomic DNAs from vertebrate and invertebrate eucaryotes detected multiple DNA bands (perhaps multiple genes) in all tested species. Drosophila DNA contains at least three hybridizing DNA bands. One of them was cloned, and found by sequence analysis, to define an Akt related gene (Dakt1). Comparison between the coding regions of c-akt and Dakt1 revealed 64.6% identity at the nucleotide level and 76.5% similarity at the amino acid level. The highest degree of homology was detected in the AH domain (68.3% similarity at the amino acid level) and the catalytic domain (83.3% similarity). Additional sequence comparisons revealed that the amino acid similarity between the catalytic domains of Dkt1 and the three known members of the Drosophila protein kinase C (PKC) family, Dpkc1, Dpkc2 and Dpkc3, is 68%, 63.6% and 67.1%, respectively. Dakt1 was mapped to Drosophila chromosome 3R 89BC. Its expression is subject to developmental regulation with the highest levels detected within the fourth hour of embryonic development. These results confirm that the AH domain of Akt defines new protein families in both vertebrate and invertebrate eucaryotes. The high degree of homology between the catalytic domains of Dkt1 and the three known members of the Drosophila PKC family suggests an evolutionarily conserved functional relationship between the members of the two families
— id: 75888, year: 1994, vol: 9, page: 141, stat: Journal Article,

The proteins encoded by c-akt and v-akt differ in post-translational modification, subcellular localization and oncogenic potential
Ahmed, N N; Franke, T F; Bellacosa, A; Datta, K; Gonzalez-Portal, M E; Taguchi, T; Testa, J R; Tsichlis, P N
1993 Jul;8(7):1957-1963, Oncogene
The acute retrovirus AKT8, isolated from an AKR mouse T-cell lymphoma, transforms mink lung cells in culture and is oncogenic when inoculated into newborn mice. The oncogene carried by this virus, v-akt, arose by recombination between Gag and the 5' untranslated region of the cellular gene c-akt. v-akt encodes a 105 kilodalton (kd) Gag-Akt fusion protein which is phosphorylated on serine and threonine residues. c-akt encodes a 55 kd serine-threonine protein-kinase, which is related to members of the protein kinase C (PKC) family and contains an SH2-like domain. The SH2-like and catalytic domains of Akt were expressed in E. coli as fusions to the carboxy-terminus of the Maltose binding protein (MBP). Antibodies against these proteins were raised in rabbits and they were used to determine the potential myristylation and subcellular localization of the v-akt and c-akt protein products. Immunoprecipitation of v-akt and c-akt from lysates of [35S]methionine and [3H]myristic acid labeled AKT8 transformed mink lung cells revealed that only v-akt was myristylated. Fractionation of Dounce-homogenized cellular extracts from uninfected and v-akt-transformed mink lung and PA317 cells and from uninfected PC12 cells by differential centrifugation showed that while the c-akt protein was localized primarily in the cytosol (90%), the v-akt protein was dispersed among the cellular compartments with approximately 40% on the plasma membranes, approximately 30% in the nucleus and approximately 30% in the cytosol. To determine whether the differences in post-translational modification and subcellular distribution between c-akt and v-akt translated into oncogenicity differences between the two proteins, we used retrovirus based constructs to express them both in the nontumorigenic rat T cell lymphoma line 5675. Intraperitoneal (IP) inoculation of the parental and c-akt expressing 5675 cells in nude Balb/c mice revealed that neither was oncogenic. In sharp contrast to these results, v-akt expressing 5675 cells inoculated in nude Balb/c mice were found to be highly oncogenic
— id: 75889, year: 1993, vol: 8, page: 1957, stat: Journal Article,

Structure, expression and chromosomal mapping of c-akt: relationship to v-akt and its implications
Bellacosa, A; Franke, T F; Gonzalez-Portal, M E; Datta, K; Taguchi, T; Gardner, J; Cheng, J Q; Testa, J R; Tsichlis, P N
1993 Mar;8(3):745-754, Oncogene
Sequence analysis of a nearly full-length murine c-akt cDNA clone and comparison with v-akt revealed the following: (a) The entire coding region of c-akt is identical to that of v-akt with the exception of five G to A transitions that do not alter the reading frame. The 3' untranslated regions of v-akt and c-akt are also identical with the exception of three single-base differences. (b) The recombination event that gave rise to v-akt occurred between the virus at nucleotide 785 from the Gag ATG codon and the 5' untranslated region of c-akt to 60 bp 5' from the c-akt ATG codon. (c) Three nucleotides absent from both Gag and c-akt were inserted at the junction between the two genes. The outcome of these events was to place, in frame, a 63-bp fragment between Gag and Akt. The resulting v-akt oncogene is predicted to encode a tripartite Gag (p12, p15, delta p30)-X-c-akt protein product. The c-akt protein contains, starting from its amino terminus, a src homology 2-like (SH2-like) domain, a domain rich in glutamic acid residues, part of which is predicted to form an amphipathic helix, and a kinase domain encoding a serine-threonine kinase with high degree of homology to members of the protein kinase C (PKC) family. The mouse c-akt is 90% homologous to human AKT1/RAC at the nucleic acid level and 98% homologous at the amino acid level. c-akt in the mouse is composed of 13 exons. The first exon contains a 5' untranslated GC-rich region. Since the recombination that gave rise to v-akt occurred with the 5' untranslated region, we hypothesize that the transduction of c-akt was preceded by provirus insertion upstream from or within the 5' untranslated region and in the same transcriptional orientation as the gene. c-akt was mapped by fluorescence in situ hybridization (FISH) to mouse chromosome 12 and rat chromosome 6 in close proximity to the Igh locus
— id: 75890, year: 1993, vol: 8, page: 745, stat: Journal Article,

AKT2, a putative oncogene encoding a member of a subfamily of protein-serine/threonine kinases, is amplified in human ovarian carcinomas
Cheng, J Q; Godwin, A K; Bellacosa, A; Taguchi, T; Franke, T F; Hamilton, T C; Tsichlis, P N; Testa, J R
1992 Oct 1;89(19):9267-9271, Proceedings of the National Academy of Sciences of the United States of America
We isolated cDNA clones containing the entire coding region of the putative oncogene AKT2. Sequence analysis and in vitro translation demonstrated that AKT2 encodes a 56-kDa protein with homology to serine/threonine kinases; moreover, this protein contains a Src homology 2-like domain. AKT2 was shown to be amplified and overexpressed in 2 of 8 ovarian carcinoma cell lines and 2 of 15 primary ovarian tumors. AKT2 was mapped to chromosome region 19q13.1-q13.2 by fluorescence in situ hybridization. In the two ovarian carcinoma cell lines exhibiting amplification of AKT2, the amplified sequences were localized within homogeneously staining regions. We conclude that AKT2 belongs to a distinct subfamily of protein-serine/threonine kinases containing Src homology 2-like domains and that alterations of AKT2 may contribute to the pathogenesis of ovarian carcinomas
— id: 75891, year: 1992, vol: 89, page: 9267, stat: Journal Article,

AKT2, a putative oncogene encoding a member of a novel subfamily of serine-threonine protein kinases is amplified and overexpressed in human ovarian carcinomas
Testa JR; Cheng JQ; Godwin AK; Bellacosa A; Franke TF; Hamilton TC; Tsichlis PN; Taguchi T
1992 ;51:38-38, American journal of human genetics
— id: 115910, year: 1992, vol: 51, page: 38, stat: Journal Article,

A molecular basis for antigen homologies of thyroid epithelial cells and plasmid-encoded proteins of enteropathogenic Yersinia enterocolitica
Franke, T F; Wenzel, B E
1991 ;12:89-92, Contributions to microbiology & immunology
— id: 75892, year: 1991, vol: 12, page: 89, stat: Journal Article,

Enteropathogenic Yersinia enterocolitica and organ-specific autoimmune diseases in man
Wenzel, B E; Heesemann, J; Heufelder, A; Franke, T F; Grammerstorf, S; Stemerowicz, R; Hopf, U
1991 ;12:80-88, Contributions to microbiology & immunology
— id: 75893, year: 1991, vol: 12, page: 80, stat: Journal Article,

Autoimmune thyroid diseases and enteropathogenic Yersinia enterocolitica
Wenzel, B E; Franke, T F; Heufelder, A E; Heesemann, J
1990 ;7(4):295-303, Autoimmunity
— id: 75894, year: 1990, vol: 7, page: 295, stat: Journal Article,

Evidence for sequence homologies between antigens of thyroid epithelial cells (TEC) and plasmid encoded antigens (RP) of enteropathogenic Yersinia enterocolitica (YE)
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1989 ;122:T26-T26, Endocrinology
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