title: Combined action of ERK and NF kappa B mediates the protective effect of phorbol ester on Fas-induced apoptosis in Jurkat cells.
abstract: The mechanisms whereby phorbol esters antagonize Fas-induced apoptosis in Jurkat T cells are poorly defined. In the present study, we report that protection from Fas-induced apoptosis by 12-O-tetradecanoylphorbol 13-acetate (TPA) is dependent on both ERK and NF kappa B activation. First, we showed that two specific mitogen-activated protein kinase/ERK kinase-inhibitors, PD98059 and U0126, both counteracted TPA-mediated suppression of Fas-induced apoptosis. Moreover, the dose-dependence of U0126-mediated inhibition of ERK phosphorylation correlated with that of reversion of the anti-apoptotic effect of TPA. Second, we observed an excellent correlation between repression of TPA-induced NF kappa B activation by an irreversible inhibitor of I kappa B alpha phosphorylation, BAY11-7082, and its ability to abrogate TPA-induced suppression of Fas-mediated apoptosis. Furthermore, we located the anti-apoptotic effect of both ERK and NF kappa B to lie upstream of the mitochondrial membrane potential depolarization event. Finally, although each inhibitor at optimal, non-toxic concentration by itself only partly reversed TPA-mediated repression of apoptosis, the combination of U0126 and BAY11-7082 completely abolished the anti-apoptotic effect of TPA. Together these findings suggest that TPA-induced activation of ERK and NF kappa B are parallel events that are both required for maximal inhibition of Fas-induced apoptosis in Jurkat T cells.
authors.affiliation: Institute of Medical Biochemistry, University of Oslo, P. O. Box 1112, Blindern, N-0317 Oslo, Norway.
authors.forename: Nikolai
authors.initials: N
authors.lastname: Engedal
authors.forename: Heidi Kiil
authors.initials: HK
authors.lastname: Blomhoff
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002070:Butadienes / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D020287:In Situ Nick-End Labeling; D019169:Jurkat Cells; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D019014:fas Receptor / Q000502:physiology*
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D005419:Flavonoids; D016328:NF-kappa B; D009570:Nitriles; C113580:U 0126; D019014:fas Receptor; D003208:Concanavalin A; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one