title: Protein kinase C regulates FADD recruitment and death-inducing signaling complex formation in Fas/CD95-induced apoptosis.
abstract: Activation of protein kinase C (PKC) triggers cellular signals that inhibit Fas/CD95-induced cell death in Jurkat T-cells by poorly defined mechanisms. Previously, we have shown that one effect of PKC on Fas/CD95-dependent cell death occurs through inhibition of cell shrinkage and K(+) efflux (Gómez-Angelats, M., Bortner, C. D., and Cidlowski, J. A. (2000) J. Biol. Chem. 275, 19609-19619). Here we report that PKC alters Fas/CD95 signaling from the plasma membrane to the activation of caspases by exerting a profound action on survival/cell death decisions. Specific activation of PKC with 12-O-tetradecanoylphorbol-13-acetate or bryostatin-1 induced translocation of PKC from the cytosol to the membrane and effectively inhibited cell shrinkage and cell death triggered by anti-Fas antibody in Jurkat cells. In contrast, inhibition of classical PKC isotypes with Gö6976 exacerbated the effect of Fas activation on both apoptotic volume decrease and cell death. PKC activation/inhibition did not affect anti-Fas antibody binding to the cell surface, intracellular levels of FADD (Fas-associated protein with death domain), or c-FLIP (cellular FLICE-like inhibitory protein) expression. However, processing/activation of both caspase-8 and caspase-3 and BID cleavage were markedly blocked upon PKC activation and, conversely, were augmented during PKC inhibition, suggesting a role for PKC upstream of caspase-8 processing and activation. Analysis of death-inducing signaling complex (DISC) formation was carried out to examine the influence of PKC on recruitment of both FADD and procaspase-8 to the Fas receptor. PKC activation blocked FADD recruitment and caspase-8 activation and thus DISC formation in both type I and II cells. In contrast, inhibition of classical PKCs promoted the opposite effect on the Fas pathway by rapidly increasing FADD recruitment, caspase-8 activation, and DISC formation. Together, these data show that PKC finely modulates Fas/CD95 signaling by altering the efficiency of DISC formation.
authors.affiliation: Laboratory of Signal Transduction, Molecular Endocrinology Group, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
authors.forename: M
authors.initials: M
authors.lastname: Gómez-Angelats
authors.forename: J A
authors.initials: JA
authors.lastname: Cidlowski
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D054713:Bryostatins; D002227:Carbazoles / Q000494:pharmacology; D002273:Carcinogens; D002352:Carrier Proteins / Q000378:metabolism*; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002469:Cell Separation; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053200:Fas-Associated Death Domain Protein; D005434:Flow Cytometry; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D019169:Jurkat Cells; D007783:Lactones / Q000494:pharmacology; D018942:Macrolides; D008934:Mitogens; D011233:Precipitin Tests; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism* / Q000502:physiology*; D021381:Protein Transport; D015398:Signal Transduction; D013347:Subcellular Fractions; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D054713:Bryostatins; D002227:Carbazoles; D002273:Carcinogens; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D007211:Indoles; D007783:Lactones; D018942:Macrolides; D008934:Mitogens; D019014:fas Receptor; C081021:Go 6976; C046785:bryostatin 1; D011493:Protein Kinase C; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D013755:Tetradecanoylphorbol Acetate