title: A JNK-dependent pathway is required for TNFalpha-induced apoptosis.
abstract: Tumor necrosis factor (TNFalpha) receptor signaling can simultaneously activate caspase 8, the transcription factor, NF-kappaB and the kinase, JNK. While activation of caspase 8 is required for TNFalpha-induced apoptosis, and induction of NF-kappaB inhibits cell death, the precise function of JNK activation in TNFalpha signaling is not clearly understood. Here, we report that TNFalpha-mediated caspase 8 cleavage and apoptosis require a sequential pathway involving JNK, Bid, and Smac/DIABLO. Activation of JNK induces caspase 8-independent cleavage of Bid at a distinct site to generate the Bid cleavage product jBid. Translocation of jBid to mitochondria leads to preferential release of Smac/DIABLO, but not cytochrome c. The released Smac/DIABLO then disrupts the TRAF2-cIAP1 complex. We propose that the JNK pathway described here is required to relieve the inhibition imposed by TRAF2-cIAP1 on caspase 8 activation and induction of apoptosis. Further, our findings define a mechanism for crosstalk between intrinsic and extrinsic cell death pathways.
authors.affiliation: Huffington Center on Aging and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 70030, USA.
authors.forename: Yibin
authors.initials: Y
authors.lastname: Deng
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Ren
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Yahong
authors.initials: Y
authors.lastname: Lin
authors.forename: Xiangwei
authors.initials: X
authors.lastname: Wu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase; D047908:Intracellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D051017:Apoptosis Regulatory Proteins; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; C494815:Bid protein, mouse; D002352:Carrier Proteins; C412403:DIABLO protein, human; C499605:Diablo protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases