Tumor necrosis factor-alpha induction of endothelial ephrin A1 expression is mediated by a p38 MAPK- and SAPK/JNK-dependent but nuclear factor-kappa B-independent mechanism.
Tumor necrosis factor-alpha (TNF-alpha) is a multifunctional cytokine that induces a broad spectrum of responses including angiogenesis. Angiogenesis promoted by TNF-alpha is mediated, at least in part, by ephrin A1, a member of the ligand family for Eph receptor tyrosine kinases. Although TNF-alpha induces ephrin A1 expression in endothelial cells, the signaling pathways mediating ephrin A1 induction remain unknown. In this study, we investigated the signaling mechanisms of TNF-alpha-dependent induction of ephrin A1 in endothelial cells. Both TNFR1 and TNFR2 appear to be involved in regulating ephrin A1 expression in endothelial cells, because neutralizing antibodies to either TNFR1 or TNFR2 inhibited TNF-alpha-induced ephrin A1 expression. Inhibition of nuclear factor-kappaB (NF-kappaB) activation by a trans-dominant inhibitory isoform of mutant IkappaBalpha did not affect ephrin A1 induction, suggesting that NF-kappaB proteins are not major regulators of ephrin A1 expression. In contrast, ephrin A1 induction was blocked by inhibition of p38 mitogen-activated protein kinase (MAPK) or SAPK/JNK, but not p42/44 MAPK, using either selective chemical inhibitors or dominant-negative forms of p38 MAPK or TNF receptor-associated factor 2. These findings indicate that TNF-alpha-induced ephrin A1 expression is mediated through JNK and p38 MAPK signaling pathways. Taken together, the results of our study demonstrated that induction of ephrin A1 in endothelial cells by TNF-alpha is mediated through both p38 MAPK and SAPK/JNK, but not p42/44 MAPK or NF-kappaB, pathways.
Department of Cell Biology, Vanderbilt University Medical School, Nashville, Tennessee 37232, USA.
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D000256:Adenoviridae / Q000235:genetics; D015703:Antigens, CD / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D036382:Ephrin-A1; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D006801:Humans; D007700:Kinetics; D008024:Ligands; D048056:Mitogen-Activated Protein Kinase 9; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism; D014176:Protein Biosynthesis; D020033:Protein Isoforms; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D015398:Signal Transduction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*; D014470:Umbilical Cord / Q000166:cytology; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases
D015703:Antigens, CD; D004791:Enzyme Inhibitors; D036382:Ephrin-A1; D005419:Flavonoids; D008024:Ligands; D016328:NF-kappa B; D020033:Protein Isoforms; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D010770:Phosphotransferases; D048056:Mitogen-Activated Protein Kinase 9; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one