title: Execution of apoptosis signal-regulating kinase 1 (ASK1)-induced apoptosis by the mitochondria-dependent caspase activation.
abstract: ASK1 activates JNK and p38 mitogen-activated protein kinases and constitutes a pivotal signaling pathway in cytokine- and stress-induced apoptosis. However, little is known about the mechanism of how ASK1 executes apoptosis. Here we investigated the roles of caspases and mitochondria in ASK1-induced apoptosis. We found that benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD-fmk), a broad-spectrum caspase inhibitor, mostly inhibited ASK1-induced cell death, suggesting that caspases are required for ASK1-induced apoptosis. Overexpression of ASK1DeltaN, a constitutively active mutant of ASK1, induced cytochrome c release from mitochondria and activation of caspase-9 and caspase-3 but not of caspase-8-like proteases. Consistently, caspase-8-deficient (Casp8 (-/-)) cells were sensitive to ASK1-induced caspase-3 activation and apoptosis, suggesting that caspase-8 is dispensable for ASK1-induced apoptosis, whereas ASK1 failed to activate caspase-3 in caspase-9-dificient (Casp9 (-/-)) cells. Moreover, mitochondrial cytochrome c release, which was not inhibited by zVAD-fmk, preceded the onset of caspase-3 activation and cell death induced by ASK1. ASK1 thus appears to execute apoptosis mainly by the mitochondria-dependent caspase activation.
authors.affiliation: Laboratory of Cell Signaling, Department of Hard Tissue Engineering, Division of Bio-Matrix, the Maxillofacial Orthognathics, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hatai
authors.forename: A
authors.initials: A
authors.lastname: Matsuzawa
authors.forename: S
authors.initials: S
authors.lastname: Inoshita
authors.forename: Y
authors.initials: Y
authors.lastname: Mochida
authors.forename: T
authors.initials: T
authors.lastname: Kuroda
authors.forename: K
authors.initials: K
authors.lastname: Sakamaki
authors.forename: K
authors.initials: K
authors.lastname: Kuida
authors.forename: S
authors.initials: S
authors.lastname: Yonehara
authors.forename: H
authors.initials: H
authors.lastname: Ichijo
authors.forename: K
authors.initials: K
authors.lastname: Takeda
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death; D002478:Cells, Cultured; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D008907:Mink; D008928:Mitochondria / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D004791:Enzyme Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; D020169:Caspases