title: Phorbol 12-myristate 13-acetate protects against tumor necrosis factor (TNF)-induced necrotic cell death by modulating the recruitment of TNF receptor 1-associated death domain and receptor-interacting protein into the TNF receptor 1 signaling complex: Implication for the regulatory role of protein kinase C.
abstract: Protein kinase C (PKC) triggers cellular signals that regulate proliferation or death in a cell- and stimulus-specific manner. Although previous studies have demonstrated that activation of PKC with phorbol 12-myristate 13-acetate (PMA) protects cells from apoptosis induced by a number of mechanisms, including death receptor ligation, little is known about the effect or mechanism of PMA in the necrotic cell death. Here, we demonstrate that PMA-mediated activation of PKC protects against tumor necrosis factor (TNF)-induced necrosis by disrupting formation of the TNF receptor (TNFR)1 signaling complex. Pretreatment with PMA protected L929 cells from TNF-induced necrotic cell death in a PKC-dependent manner, but it did not protect against DNA-damaging agents, including doxorubicin (Adriamycin) and camptothecin. Analysis of the upstream signaling events affected by PMA revealed that it markedly inhibited the TNF-induced recruitment of TNFR1-associated death domain protein (TRADD) and receptor-interacting protein (RIP) to TNFR1, subsequently inhibiting TNF-induced activation of nuclear factor-kappaB and c-Jun NH2-terminal kinase (JNK). However, JNK inhibitors do not significantly affect TNF-induced necrosis, suggesting that the inhibition of JNK activation by PMA is not part of the antinecrotic mechanism. In addition, PMA acted as an antagonist of TNF-induced reactive oxygen species (ROS) production, thereby suppressing activation of ROS-mediated poly(ADP-ribose)polymerase (PARP), and thus inhibiting necrotic cell death. Furthermore, during TNF-induced necrosis, PARP was significantly activated in wild-type mouse embryonic fibroblast (MEF) cells but not in RIP-/- or TNFR-associated factor 2-/-MEF cells. Taken together, these results suggest that PKC activation ensures effective shutdown of the death receptor-mediated necrotic cell death pathway by modulating formation of the death receptor signaling complex.
authors.affiliation: Department of Pharmacology, College of Medicine, Chungnam National University, 6 Munhwa-dong, Jung-gu, Daejeon 301-131, Korea.
authors.forename: Hee Sun
authors.initials: HS
authors.lastname: Byun
authors.forename: Kyeong Ah
authors.initials: KA
authors.lastname: Park
authors.forename: Minho
authors.initials: M
authors.lastname: Won
authors.forename: Keum-Jin
authors.initials: KJ
authors.lastname: Yang
authors.forename: Sanghee
authors.initials: S
authors.lastname: Shin
authors.forename: Longzhen
authors.initials: L
authors.lastname: Piao
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
authors.forename: Zee-Won
authors.initials: ZW
authors.lastname: Lee
authors.forename: Jongsun
authors.initials: J
authors.lastname: Park
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Seok
authors.forename: Zheng-Gang
authors.initials: ZG
authors.lastname: Liu
authors.forename: Gang Min
authors.initials: GM
authors.lastname: Hur
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis; D009687:Nuclear Proteins / Q000378:metabolism*; D000078723:Nuclear Receptor Interacting Protein 1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D053199:TNF Receptor-Associated Death Domain Protein; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016328:NF-kappa B; D009687:Nuclear Proteins; D000078723:Nuclear Receptor Interacting Protein 1; D017382:Reactive Oxygen Species; D047888:Receptors, Tumor Necrosis Factor, Type I; D053199:TNF Receptor-Associated Death Domain Protein; C481226:Tradd protein, mouse; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D014409:Tumor Necrosis Factor-alpha; D011065:Poly(ADP-ribose) Polymerases; D011493:Protein Kinase C; D048031:JNK Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate