151
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Park SJ, Kim YY, Lim JY, Seo GJ, Kim J, Park SI, Park BJ. Opposite role of Ras in tumor necrosis factor-alpha-induced cell cycle regulation: competition for Raf kinase. Biochem Biophys Res Commun 2001; 287:1140-7. [PMID: 11587542 DOI: 10.1006/bbrc.2001.5713] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ras, a well-known oncogene, induces cell cycle stimulation through the Raf/Erk pathway and leads to cellular transformation, accompanied by other oncogenes such as c-myc and viral oncogenic protein. Here we suggest the interfering role of Ras in tumor necrosis factor (TNF)-alpha-induced cell cycle regulation. In TSU-Pr1 and T24 (oncogenic Ras cell lines), TNF-alpha suppresses cell cycle progression without induction of apoptosis, whereas AGS (wild-type Ras) is stimulated in its cell cycle by TNF-alpha coupled with activation of Erk. However, in TSU-Pr1 and T24, TNF-alpha leads to dephosphorylation of Erk1/2. Inhibition or activation of Ras can restore or convert TNF-alpha-induced cell cycle regulation in the cell lines containing the oncogenic Ras (TSU-Pr1 and T24) or AGS, respectively. Regulation of Erk also shows the coincidental pattern. We suggest the competition between the Ras pathway and TNF signaling for the binding to Raf, a common downstream target, as the cause of such reciprocal response, based on co-immunoprecipitation (co-IP) with antibodies against Raf and Ras or cellular Flice-inhibitory protein (c-FLIP), which have been recently identified upstream of Raf in death-ligand-induced cell cycle stimulation. Overexpression of Raf in TSU-Pr1, to reduce the competition, overcomes TNF-induced cell cycle arrest, also supporting our hypotheses.
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Affiliation(s)
- S J Park
- Department of Cancer Research, National Institute of Health, Seoul, Republic of Korea
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152
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O'toole A, Moule SK, Lockyer PJ, Halestrap AP. Tumour necrosis factor-alpha activation of protein kinase B in WEHI-164 cells is accompanied by increased phosphorylation of Ser473, but not Thr308. Biochem J 2001; 359:119-27. [PMID: 11563975 PMCID: PMC1222127 DOI: 10.1042/0264-6021:3590119] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Tumour necrosis factor-alpha (TNF-alpha) may activate both cell survival and cell death pathways. In the murine fibrosarcoma cell line WEHI-164, physiological concentrations (1 ng/ml) of TNF-alpha induced wortmannin-sensitive cell ruffling characteristic of the phosphoinositide 3-kinase (PI3-kinase) activation associated with cell survival. Wortmannin also enhanced cell death induced by TNF-alpha in the presence of actinomycin D, confirming that TNF-alpha activates a transcription-independent survival pathway requiring PI3-kinase activity. Both TNF-alpha and insulin-like growth factor 1 (IGF-1) caused a 6-10-fold wortmannin-sensitive increase in protein kinase B (PKB) activity within 5 min. For IGF-1, this was associated with an increase in phosphorylation of both Thr(308) and Ser(473), whereas for TNF-alpha only phosphorylation of Ser(473) was increased, even in the presence of okadaic acid to inhibit protein phosphatases 1 and 2A. TNF-alpha did not decrease the phosphorylation of Thr(308) induced by IGF-1, implying that TNF-alpha neither inhibits phosphoinositide-dependent kinase 1 (PDK1) nor activates an opposing phosphatase. In WEHI cells overexpressing a form of PKB, IGF-1 increased phosphorylation of Ser(473) on PKB, but not its kinase activity, whereas TNF-alpha failed to induce Ser(473) phosphorylation or kinase activation of either overexpressed T308A or wild-type PKB (where T308A is the mutant bearing the substitution Thr(308)-->A). IGF-1 caused translocation of green-fluorescent-protein-tagged ADP-ribosylation factor nucleotide-binding site opener (ARNO) to the plasma membrane of WEHI cells, but this was not detected with TNF-alpha. We conclude that, at physiological concentrations, TNF-alpha activates endogenous PKB by stimulating PDK2 (increase in Ser(473) phosphorylation) in a PI3-kinase-dependent (wortmannin-sensitive) manner, without causing detectable stimulation of PDK1 (no increase in Thr(308) phosphorylation) or ARNO translocation. Possible explanations of these observations are discussed.
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Affiliation(s)
- A O'toole
- Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
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153
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Blum S, Issbrüker K, Willuweit A, Hehlgans S, Lucerna M, Mechtcheriakova D, Walsh K, von der Ahe D, Hofer E, Clauss M. An inhibitory role of the phosphatidylinositol 3-kinase-signaling pathway in vascular endothelial growth factor-induced tissue factor expression. J Biol Chem 2001; 276:33428-34. [PMID: 11445586 DOI: 10.1074/jbc.m105474200] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) is not only essential for vasculogenesis and angiogenesis but is also capable of inducing tissue factor, the prime initiator of coagulation, in endothelial cells. In this study we have analyzed the VEGF-elicited pathways involved in the induction of tissue factor in human umbilical cord vein endothelial cells. Using specific low molecular weight inhibitors we could demonstrate a crucial role of the p38 and Erk-1/2 mitogen-activated protein (MAP) kinases. In contrast, treatment with wortmannin or LY294002, inhibitors of phosphatidylinositol 3 (PI3)-kinase, resulted in a strong enhancement of the VEGF-induced tissue factor production, indicating a negative regulatory role of the PI3-kinase on tissue factor-inducing pathways. Accordingly, transduction with constitutively active Akt led to a reduction of VEGF-induced tissue factor production. Western blot analyses using antibodies specific for phosphorylated p38 showed an enhanced activation of this MAP kinase in human umbilical cord vein endothelial cells when stimulated with VEGF in the presence of wortmannin in comparison to either agent alone. Thus, the negative regulation of the PI3-kinase pathway on endothelial tissue factor activity can be explained at least in part by a suppression of this MAP kinase-signaling pathway. This is the first demonstration of a reciprocal relationship between procoagulant activity and the PI3-kinase-Akt signaling pathway, and it reveals a novel mechanism by which tissue factor expression can be controlled in endothelial cells.
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Affiliation(s)
- S Blum
- Department of Molecular Cell Biology, Max Planck Institute for Physiological and Clinical Research, 61231 Bad Nauheim, Germany
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154
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Bauvy C, Gane P, Arico S, Codogno P, Ogier-Denis E. Autophagy delays sulindac sulfide-induced apoptosis in the human intestinal colon cancer cell line HT-29. Exp Cell Res 2001; 268:139-49. [PMID: 11478840 DOI: 10.1006/excr.2001.5285] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Autophagy is a major catabolic process allowing the renewal of intracellular organelles by which cells maintain their homeostasis. We have previously shown that autophagy is controlled by two transduction pathways mediated by a heterotrimeric Gi3 protein and phosphatidylinositol 3-kinase activities in the human colon cancer cell line HT-29. Here, we show that 3-methyladenine, an inhibitor of autophagy, increases the sensitivity of HT-29 cells to apoptosis induced by sulindac sulfide, a nonsteroidal anti-inflammatory drug which inhibits the cyclooxygenases. Similarly, HT-29 cells overexpressing a GTPase-deficient mutant of the G(alpha i3) protein (Q204L), which have a low rate of autophagy, were more sensitive to sulindac sulfide-induced apoptosis than parental HT-29 cells. In both cell populations we did not observe differences in the expression patterns of COX-2, Bcl-2, Bcl(XL), Bax, and Akt/PKB activity. However, the rate of cytochrome c release was higher in Q204L-overexpressing cells than in HT-29 cells. These results suggest that autophagy could retard apoptosis in colon cancer cells by sequestering mitochondrial death-promoting factors such as cytochrome c.
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Affiliation(s)
- C Bauvy
- INSERM U504 Glycobiologie et Signalisation Cellulaire, 16, Avenue Paul-Vaillant Couturier, 94807 Villejuif Cedex, France
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155
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Gratton JP, Morales-Ruiz M, Kureishi Y, Fulton D, Walsh K, Sessa WC. Akt down-regulation of p38 signaling provides a novel mechanism of vascular endothelial growth factor-mediated cytoprotection in endothelial cells. J Biol Chem 2001; 276:30359-65. [PMID: 11387313 DOI: 10.1074/jbc.m009698200] [Citation(s) in RCA: 236] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) utilizes a phosphoinositide 3-kinase (PI 3-kinase)/Akt signaling pathway to protect endothelial cells from apoptotic death. Here we show that PI 3-kinase/Akt signaling promotes endothelial cell survival by inhibiting p38 mitogen-activated protein kinase (MAPK)-dependent apoptosis. Blockade of the PI 3-kinase or Akt pathways in conjunction with serum withdrawal stimulates p38-dependent apoptosis. Blockade of PI 3-kinase/Akt also led to enhanced VEGF activation of p38 and apoptosis. In this context, the pro-apoptotic effect of VEGF is attenuated by the p38 MAPK inhibitor SB203580. VEGF stimulation of endothelial cells or infection with an adenovirus expressing constitutively active Akt causes MEKK3 phosphorylation, which is associated with decreased MEKK3 kinase activity and down-regulation of MKK3/6 and p38 MAPK activation. Conversely, activation-deficient Akt decreases VEGF-stimulated MEKK3 phosphorylation and increases MKK/p38 activation. Activation of MKK3/6 is not dependent on Rac activation since dominant negative Rac does not decrease p38 activation triggered by inhibition of PI 3-kinase. Thus, cross-talk between the Akt and p38 MAPK pathways may regulate the level of cytoprotection versus apoptosis and is a new mechanism to explain the cytoprotective actions of Akt.
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Affiliation(s)
- J P Gratton
- Department of Pharmacology and Molecular Cardiobiology Program, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA
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156
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Perlman H, Pagliari LJ, Nguyen N, Bradley K, Liu H, Pope RM. The Fas-FasL death receptor and PI3K pathways independently regulate monocyte homeostasis. Eur J Immunol 2001; 31:2421-30. [PMID: 11500826 DOI: 10.1002/1521-4141(200108)31:8<2421::aid-immu2421>3.0.co;2-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Peripheral blood-derived monocytes spontaneously undergo apoptosis mediated by Fas-Fas ligand (FasL) interactions. Activation of monocytes by LPS or TNF-alpha prevents spontaneous monocyte apoptosis through an unknown mechanism. Here, we demonstrate that LPS and TNF-alpha up-regulate Flip and suppress spontaneous Fas-FasL mediated monocyte apoptosis and caspase 8 and 3 activation. Flip was responsible for this protection, since inhibition of Flip by antisense oligonucleotides in the presence of LPS or TNF-alpha restored monocyte sensitivity to spontaneous apoptosis. We also investigated whether the PI3K pathway contributes to the suppression of spontaneous monocyte apoptosis mediated by LPS and TNF-alpha. Monocytes treated with a reversible PI3K inhibitor (LY294002) displayed enhanced apoptosis, while LPS and TNF-alpha partially protected against apoptosis mediated by LY294002. However, direct suppression of Fas-FasL interactions by addition of neutralizing anti-FasL antibody did not further suppress LY294002-induced apoptosis in the presence of LPS or TNF-alpha. Collectively, these data demonstrate that LPS or TNF-alpha protect monocytes from death receptor-mediated apoptosis through the up-regulation of Flip, but not apoptosis initiated by inhibition of the PI3K pathway.
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Affiliation(s)
- H Perlman
- Northwestern University Medical School and the Veterans Administration Chicago Healthcare System, Lakeside Division, Division of Rheumatology, Chicago, IL 60611, USA
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157
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Osawa Y, Banno Y, Nagaki M, Brenner DA, Naiki T, Nozawa Y, Nakashima S, Moriwaki H. TNF-alpha-induced sphingosine 1-phosphate inhibits apoptosis through a phosphatidylinositol 3-kinase/Akt pathway in human hepatocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:173-80. [PMID: 11418646 DOI: 10.4049/jimmunol.167.1.173] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Human hepatocytes usually are resistant to TNF-alpha cytotoxicity. In mouse or rat hepatocytes, repression of NF-kappaB activation is sufficient to induce TNF-alpha-mediated apoptosis. However, in both Huh-7 human hepatoma cells and Hc human normal hepatocytes, when infected with an adenovirus expressing a mutated form of IkappaBalpha (Ad5IkappaB), which almost completely blocks NF-kappaB activation, >80% of the cells survived 24 h after TNF-alpha stimulation. Here, we report that TNF-alpha activates other antiapoptotic factors, such as sphingosine kinase (SphK), phosphatidylinositol 3-kinase (PI3K), and Akt kinase. Pretreatment of cells with N,N-dimethylsphingosine (DMS), an inhibitor of SphK, or LY 294002, an inhibitor of PI3K that acts upstream of Akt, increased the number of apoptotic cells induced by TNF-alpha in Ad5IkappaB-infected Huh-7 and Hc cells. TNF-alpha-induced activations of PI3K and Akt were inhibited by DMS. In contrast, exogenous sphingosine 1-phosphate, a product of SphK, was found to activate Akt and partially rescued the cells from TNF-alpha-induced apoptosis. Although Akt has been reported to activate NF-kappaB, DMS and LY 294002 failed to prevent TNF-alpha-induced NF-kappaB activation, suggesting that the antiapoptotic effects of SphK and Akt are independent of NF-kappaB. Furthermore, apoptosis mediated by Fas ligand (FasL) involving Akt activation also was potentiated by DMS pretreatment in Hc cells. Sphingosine 1-phosphate administration partially protected cells from FasL-mediated apoptosis. These results indicate that not only NF-kappaB but also SphK and PI3K/Akt are involved in the signaling pathway(s) for protection of human hepatocytes from the apoptotic action of TNF-alpha and probably FasL.
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Affiliation(s)
- Y Osawa
- First Department of Internal Medicine and Department of Biochemistry, Gifu University School of Medicine, Gifu, Japan
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158
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Abstract
Vascular endothelium is a major target of actions of the proinflammatory cytokine tumor necrosis factor (TNF). Increasingly, the intracellular pathways that are activated in response to TNF have been elucidated. Many of these pathways have proven to be cell type-specific, requiring that observations made in other cell types be confirmed or ruled out in endothelial cells (EC). In this review the authors will summarize the state of the field, emphasizing studies in cultured human EC.
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Affiliation(s)
- L A Madge
- Department of Pathology and the Interdepartmental Program in Vascular Biology and Transplantation, Yale University School of Medicine, New Haven, Connecticut, 06520, USA
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159
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Gustin JA, Maehama T, Dixon JE, Donner DB. The PTEN tumor suppressor protein inhibits tumor necrosis factor-induced nuclear factor kappa B activity. J Biol Chem 2001; 276:27740-4. [PMID: 11356844 DOI: 10.1074/jbc.m102559200] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nuclear factor kappaB (NF-kappaB) transcriptionally activates genes that promote immunity and cell survival. Activation of NF-kappaB is induced by an IkappaB kinase (IKK) complex that phosphorylates and promotes dissociation of IkappaB from NF-kappaB, which then translocates into the nucleus. Activation of phosphatidylinositol (PI) 3-kinase/Akt signaling by tumor necrosis factor (TNF) activates IKK and NF-kappaB. The present study shows that PTEN, a tumor suppressor that inhibits PI 3-kinase function, impairs TNF activation of Akt and the IKK complex in 293 cells. Transient expression of PTEN suppressed IKK activation and TNF-induced NF-kappaB DNA binding and transactivation. Studies were conducted with PC-3 prostate cancer cells that do not express PTEN and DU145 prostate cancer cells that express PTEN. TNF activated Akt in PC-3 cells, but not in DU145 cells, and the ability of TNF to activate NF-kappaB was blocked by pharmacological inhibition of PI 3-kinase activity in PC-3 cells, but not in DU145 cells. Expression of PTEN in PC-3 cells to a level comparable with that endogenously present in DU145 cells inhibited TNF activation of NF-kappaB. The cell type-specific ability of PTEN to negatively regulate the PI 3-kinase/AKT/NF-kappaB pathway may be important to its tumor suppressor activity.
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Affiliation(s)
- J A Gustin
- Department of Microbiology and Immunology and Walther Oncology Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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160
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Bannerman DD, Tupper JC, Ricketts WA, Bennett CF, Winn RK, Harlan JM. A constitutive cytoprotective pathway protects endothelial cells from lipopolysaccharide-induced apoptosis. J Biol Chem 2001; 276:14924-32. [PMID: 11279137 DOI: 10.1074/jbc.m100819200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipopolysaccharide (LPS) has been implicated as the bacterial component responsible for much of the endothelial cell injury/dysfunction associated with Gram-negative bacterial infections. Protein synthesis inhibition is required to sensitize the endothelium to lipopolysaccharide-induced apoptosis, suggesting that a constitutive or inducible cytoprotective protein(s) is required for endothelial survival. We have identified two known endothelial anti-apoptotic proteins, c-FLIP and Mcl-1, the expression of which is decreased markedly in the presence of cycloheximide. Decreased expression of both proteins preceded apoptosis evoked by lipopolysaccharide + cycloheximide. Caspase inhibition protected against apoptosis, but not the decreased expression of c-FLIP and Mcl-1, suggesting that they exert protection upstream of caspase activation. Inhibition of the degradation of these two proteins with the proteasome inhibitor, lactacystin, prevented lipopolysaccharide + cycloheximide-induced apoptosis. Similarly, lactacystin protected against endothelial apoptosis induced by either tumor necrosis factor-alpha or interleukin-1beta in the presence of cycloheximide. That apoptosis could be blocked in the absence of new protein synthesis by inhibition of the proteasome degradative pathway implicates the requisite involvement of a constitutively expressed protein(s) in the endothelial cytoprotective pathway. Finally, reduction of FLIP expression with antisense oligonucleotides sensitized endothelial cells to LPS killing, demonstrating a definitive role for FLIP in the protection of endothelial cells from LPS-induced apoptosis.
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Affiliation(s)
- D D Bannerman
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington 98104, USA.
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161
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Zhang L, Himi T, Morita I, Murota S. Inhibition of phosphatidylinositol-3 kinase/Akt or mitogen-activated protein kinase signaling sensitizes endothelial cells to TNF-alpha cytotoxicity. Cell Death Differ 2001; 8:528-36. [PMID: 11423913 DOI: 10.1038/sj.cdd.4400838] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2000] [Revised: 11/27/2000] [Accepted: 12/14/2000] [Indexed: 11/09/2022] Open
Abstract
Bovine carotid artery endothelial (BAE) cells are resistant to tumor necrosis factor-alpha (TNF), like most other cells. We examined if mitogen-activated protein (MAP) kinase and phosphatidylinositol-3 (PI3) kinase/Akt pathways are involved in this effect. In BAE cells, TNF activates MAP kinase in a MAP kinase kinase 1 (MEK1) manner and Akt in PI3-kinase-dependent manner. Pretreatment with either the MEK1 inhibitor U0126 or PI3-kinase inhibitor LY294002 sensitized BAE cells to TNF-induced apoptosis. Neither U0126 nor LY294002 pretreatment affected TNF-induced activation of NF-kappaB, suggesting that the MAP kinase or PI3-kinase/Akt-mediated anti-apoptotic effect induced by TNF was not relevant to NF-kappaB activation. Both MAP kinase and PI3-kinase/Akt -mediated signaling could prevent cytochrome c release and mitochondrial transmembrane potential (Deltapsi) decrease. PI3-kinase/Akt signaling attenuated caspase-8 activity, whereas MAP kinase signaling impaired caspase-9 activity. These results suggest that TNF-induced MAP kinase and PI3-kinase/Akt signaling play important roles in protecting BAE cells from TNF cytotoxicity.
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Affiliation(s)
- L Zhang
- Department of Cellular Physiological Chemistry, Graduate School, Tokyo Medical and Dental University 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
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162
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Annerén C, Welsh M. Increased Cytokine-Induced Cytotoxicity of Pancreatic Islet Cells from Transgenic Mice Expressing the Src-like Tyrosine Kinase GTK. Mol Med 2001. [DOI: 10.1007/bf03402213] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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163
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Kim F, Gallis B, Corson MA. TNF-alpha inhibits flow and insulin signaling leading to NO production in aortic endothelial cells. Am J Physiol Cell Physiol 2001; 280:C1057-65. [PMID: 11287317 DOI: 10.1152/ajpcell.2001.280.5.c1057] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelial cells release nitric oxide (NO) acutely in response to increased "flow" or fluid shear stress (FSS), and the increase in NO production is correlated with enhanced phosphorylation and activation of endothelial nitric oxide synthase (eNOS). Both vascular endothelial growth factor and FSS activate endothelial protein kinase B (PKB) by way of incompletely understood pathway(s), and, in turn, PKB phosphorylates eNOS at Ser-1179, causing its activation. In this study, we found that either FSS or insulin stimulated insulin receptor substrate-1 (IRS-1) tyrosine and serine phosphorylation and increased IRS-1-associated phosphatidylinositol 3-kinase activity, phosphorylation of PKB Ser-473, phosphorylation of eNOS Ser-1179, and NO production. Brief pretreatment of bovine aortic endothelial cells with tumor necrosis factor-alpha (TNF-alpha) inhibited the above described FSS- or insulin-stimulated protein phosphorylation events and almost totally inhibited FSS- or insulin-stimulated NO production. These data indicate that FSS and insulin regulate eNOS phosphorylation and NO production by overlapping mechanisms. This study suggests one potential mechanism for the development of endothelial dysfunction in disease states with alterations in insulin regulation and increased TNF-alpha levels.
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Affiliation(s)
- F Kim
- Department of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington, Seattle, Washington 98104, USA.
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164
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Uranishi H, Tetsuka T, Yamashita M, Asamitsu K, Shimizu M, Itoh M, Okamoto T. Involvement of the pro-oncoprotein TLS (translocated in liposarcoma) in nuclear factor-kappa B p65-mediated transcription as a coactivator. J Biol Chem 2001; 276:13395-401. [PMID: 11278855 DOI: 10.1074/jbc.m011176200] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we have demonstrated that translocated in liposarcoma (TLS), also termed FUS, is an interacting molecule of the p65 (RelA) subunit of the transcription factor nuclear factor kappaB (NF-kappaB) using a yeast two-hybrid screen. We confirmed the interaction between TLS and p65 by the pull-down assay in vitro and by a coimmunoprecipitation experiment followed by Western blot of the cultured cell in vivo. TLS was originally identified as part of a fusion protein with CHOP arising from chromosomal translocation in human myxoid liposarcomas. TLS has been shown to be involved in TFIID complex formation and associated with RNA polymerase II. However, the role of TLS in transcriptional regulation has not yet been clearly elucidated. We found that TLS enhanced the NF-kappaB-mediated transactivation induced by physiological stimuli such as tumor necrosis factor alpha, interleukin-1beta, and overexpression of NF-kappaB-inducing kinase. TLS augmented NF-kappaB-dependent promoter activity of the intercellular adhesion molecule-1 gene and interferon-beta gene. These results suggest that TLS acts as a coactivator of NF-kappaB and plays a pivotal role in the NF-kappaB-mediated transactivation.
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Affiliation(s)
- H Uranishi
- Department of Molecular Genetics and First Department of Internal Medicine, Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8601, Japan
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165
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Chiang SH, Baumann CA, Kanzaki M, Thurmond DC, Watson RT, Neudauer CL, Macara IG, Pessin JE, Saltiel AR. Insulin-stimulated GLUT4 translocation requires the CAP-dependent activation of TC10. Nature 2001; 410:944-8. [PMID: 11309621 DOI: 10.1038/35073608] [Citation(s) in RCA: 428] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The stimulation of glucose uptake by insulin in muscle and adipose tissue requires translocation of the GLUT4 glucose transporter protein from intracellular storage sites to the cell surface. Although the cellular dynamics of GLUT4 vesicle trafficking are well described, the signalling pathways that link the insulin receptor to GLUT4 translocation remain poorly understood. Activation of phosphatidylinositol-3-OH kinase (PI(3)K) is required for this trafficking event, but it is not sufficient to produce GLUT4 translocation. We previously described a pathway involving the insulin-stimulated tyrosine phosphorylation of Cbl, which is recruited to the insulin receptor by the adapter protein CAP. On phosphorylation, Cbl is translocated to lipid rafts. Blocking this step completely inhibits the stimulation of GLUT4 translocation by insulin. Here we show that phosphorylated Cbl recruits the CrkII-C3G complex to lipid rafts, where C3G specifically activates the small GTP-binding protein TC10. This process is independent of PI(3)K, but requires the translocation of Cbl, Crk and C3G to the lipid raft. The activation of TC10 is essential for insulin-stimulated glucose uptake and GLUT4 translocation. The TC10 pathway functions in parallel with PI(3)K to stimulate fully GLUT4 translocation in response to insulin.
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Affiliation(s)
- S H Chiang
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, Michigan 48105, USA
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166
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Weaver SA, Russo MP, Wright KL, Kolios G, Jobin C, Robertson DA, Ward SG. Regulatory role of phosphatidylinositol 3-kinase on TNF-alpha-induced cyclooxygenase 2 expression in colonic epithelial cells. Gastroenterology 2001; 120:1117-27. [PMID: 11266376 DOI: 10.1053/gast.2001.23257] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND AIMS Cyclooxygenase (COX)-2 is up-regulated in most colonic cancers and in inflammatory bowel disease in which tumor necrosis factor (TNF)-alpha is believed to play a central role. There has been recent speculation on the activation of phosphatidylinositol 3-kinase (PI 3-kinase) by TNF-alpha and its role in the regulation of genes controlled by NF-kappaB. We investigated the regulatory role of PI 3-kinase on COX-2 expression in colonic epithelial cells. METHODS In HT-29 and Caco-2 colonic epithelial cells, COX-2 expression was induced by either TNF-alpha or interleukin (IL)-1alpha as observed by Northern and Western analyses. COX-2 activity was assessed by measuring prostaglandin E(2) (PGE2) production by enzyme-linked immunosorbent assay. NF-kappaB binding activity was assessed by electrophoretic mobility shift assay. PI 3-kinase activity was measured by quantifying the accumulation of PI 3-kinase-dependent D-3 lipid products by high-performance liquid chromatography. RESULTS The PI 3-kinase inhibitor wortmannin up-regulated induced COX-2 expression in a concentration-dependent manner in both HT-29 and Caco-2 cells. An alternative PI 3-kinase inhibitor, LY294002, caused up-regulation of induced COX-2 messenger RNA (mRNA) in HT-29 cells at concentrations of < or =1 micromol/L. IL-4 and IL-13, which are known to activate PI 3-kinase, down-regulated HT-29 COX-2 mRNA, protein, and PGE2 production. NF-kappaB binding activity was unaltered by PI 3-kinase inhibition in HT-29 cells, in which TNF-alpha was shown to activate PI 3-kinase directly. CONCLUSIONS COX-2 is negatively regulated by PI 3-kinase; we propose that the inhibitory effect of IL-4 and IL-13 is mediated via a PI 3-kinase-dependent pathway. This mechanism does not appear to involve NF-kappaB because PI 3-kinase inhibition did not alter NF-kappaB binding activity. TNF-alpha can activate PI 3-kinase directly in addition to inducing COX-2.
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Affiliation(s)
- S A Weaver
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, England.
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167
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Habib AA, Chatterjee S, Park SK, Ratan RR, Lefebvre S, Vartanian T. The epidermal growth factor receptor engages receptor interacting protein and nuclear factor-kappa B (NF-kappa B)-inducing kinase to activate NF-kappa B. Identification of a novel receptor-tyrosine kinase signalosome. J Biol Chem 2001; 276:8865-74. [PMID: 11116146 DOI: 10.1074/jbc.m008458200] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcription factor nuclear factor-kappaB (NF-kappaB) is activated by a diverse number of stimuli including tumor necrosis factor-alpha, interleukin-1, UV irradiation, viruses, as well as receptor tyrosine kinases such as the epidermal growth factor receptor (EGFR). NF-kappaB activation by the tumor necrosis factor receptor (TNFR) involves the formation of a multiprotein complex termed a signalosome. Although previous studies have shown that the activated EGFR can induce NF-kappaB, the mechanism of this activation remains unknown. In this study, we identify components of the signalosome formed by the activated EGFR required to activate NF-kappaB and show that, although the activated EGFR uses mechanisms similar to the TNFR, it recruits a distinct signalosome. We show the EGFR forms a complex with a TNFR-interacting protein (RIP), which plays a key role in TNFR-induced NF-kappaB activation, but not with TRADD, an adaptor protein which serves to recruit RIP to the TNFR. Furthermore, we show that the EGFR associates with NF-kappaB-inducing kinase (NIK) and provide evidence suggesting multiprotein complex formation between the EGFR, RIP, and NIK. Using a dominant negative NIK mutant, we show that NIK activation is required for EGFR-mediated NF-kappaB induction. We also show that a S32/36 IkappaBalpha mutant blocks EGFR-induced NF-kappaB activation. Our studies also suggest that a high level of EGFR expression, a frequent occurrence in human tumors, is optimal for epidermal growth factor-induced NF-kappaB activation. Finally, although protein kinase B/Akt has been implicated in tumor necrosis factor and PDGF-induced NF-kappaB activation, our studies do not support a role for this protein in EGFR-induced NF-kappaB activation.
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Affiliation(s)
- A A Habib
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA.
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168
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Bui NT, Livolsi A, Peyron JF, Prehn JH. Activation of nuclear factor kappaB and Bcl-x survival gene expression by nerve growth factor requires tyrosine phosphorylation of IkappaBalpha. J Cell Biol 2001; 152:753-64. [PMID: 11266466 PMCID: PMC2195773 DOI: 10.1083/jcb.152.4.753] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
NGF has been shown to support neuron survival by activating the transcription factor nuclear factor-kappaB (NFkappaB). We investigated the effect of NGF on the expression of Bcl-xL, an anti-apoptotic Bcl-2 family protein. Treatment of rat pheochromocytoma PC12 cells, human neuroblastoma SH-SY5Y cells, or primary rat hippocampal neurons with NGF (0.1-10 ng/ml) increased the expression of bcl-xL mRNA and protein. Reporter gene analysis revealed a significant increase in NFkappaB activity after treatment with NGF that was associated with increased nuclear translocation of the active NFkappaB p65 subunit. NGF-induced NFkappaB activity and Bcl-xL expression were inhibited in cells overexpressing the NFkappaB inhibitor, IkappaBalpha. Unlike tumor necrosis factor-alpha (TNF-alpha), however, NGF-induced NFkappaB activation occurred without significant degradation of IkappaBs determined by Western blot analysis and time-lapse imaging of neurons expressing green fluorescent protein-tagged IkappaBalpha. Moreover, in contrast to TNF-alpha, NGF failed to phosphorylate IkappaBalpha at serine residue 32, but instead caused significant tyrosine phosphorylation. Overexpression of a Y42F mutant of IkappaBalpha potently suppressed NFG-, but not TNF-alpha-induced NFkappaB activation. Conversely, overexpression of a dominant negative mutant of TNF receptor-associated factor-6 blocked TNF-alpha-, but not NGF-induced NFkappaB activation. We conclude that NGF and TNF-alpha induce different signaling pathways in neurons to activate NFkappaB and bcl-x gene expression.
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Affiliation(s)
- Nguyen Truc Bui
- Interdisciplinary Center for Clinical Research, Research Group “Apoptosis and Cell Death,”, D-48149 Münster, Germany
| | - Antonia Livolsi
- Institut National de la Santé et de la Recherche Médicale U526 “Hematopoietic Cell Activation, ” Faculte de Medecine Pasteur, 06107 Nice, France
| | - Jean-Francois Peyron
- Institut National de la Santé et de la Recherche Médicale U526 “Hematopoietic Cell Activation, ” Faculte de Medecine Pasteur, 06107 Nice, France
| | - Jochen H.M. Prehn
- Interdisciplinary Center for Clinical Research, Research Group “Apoptosis and Cell Death,”, D-48149 Münster, Germany
- Department of Pharmacology and Toxicology, Faculty of Medicine, Westphalian Wilhelms-University, D-48149 Münster, Germany
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169
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Krutzik SR, Sieling PA, Modlin RL. The role of Toll-like receptors in host defense against microbial infection. Curr Opin Immunol 2001; 13:104-8. [PMID: 11154925 DOI: 10.1016/s0952-7915(00)00189-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Toll family of proteins is central to Drosophila host defense against microbial infection. Maintained throughout evolution, mammalian Toll-like receptors (TLRs) are proteins that participate in innate immunity to bacteria in at least four ways. First, TLRs participate in the recognition of molecular patterns present on microorganisms. Second, TLRs are expressed at the interface with the environment, the site of microbial invasion. Third, activation of TLRs induces expression of co-stimulatory molecules and the release of cytokines that instruct the adaptive immune response. Fourth, activation of TLRs leads to direct antimicrobial effector pathways that can result in elimination of the foreign invader. The recent investigation of TLRs in these areas has provided new insights into mechanisms of innate immunity.
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Affiliation(s)
- S R Krutzik
- Division of Dermatology, Department of Medicine, University of California (Los Angeles) School of Medicine, Los Angeles, CA 90095, USA
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170
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Abstract
The programmed form of cell death (apoptosis) is essential for normal development of multicellular organisms. In the past few years, compelling evidence accumulated that dysregulation of apoptosis can lead to embryonal death and is involved in the pathophysiology of various inflammatory and degenerative diseases. Specifically, the occurrence of endothelial cell apoptosis has deleterious effects on the development of the cardiovascular system leading to embryonal death. Moreover, endothelial cell apoptosis counteracts neovascularization in the adult organism. On the basis of these findings, one may consider the regulation of endothelial cell apoptosis as a potential therapeutic target. The induction of endothelial cell apoptosis may limit unwanted neovascularization of tumors. In contrast, the prevention of endothelial cell apoptosis may improve angiogenesis and vasculogenesis in patients with ischemia. The present work critically reviews the existing data that supports a role of endothelial cell apoptosis for vascular growth and remodeling and provides insights into the mechanisms and the potential therapeutic consequences.
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Affiliation(s)
- S Dimmeler
- Molecular Cardiology, Department of Internal Medicine IV, University of Frankfurt, Germany.
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