title: Blocking caspase-3-mediated proteolysis of IKKbeta suppresses TNF-alpha-induced apoptosis.
abstract: The transcription factor NF-kappaB is essential for survival of many cell types. However, cells can undergo apoptosis despite the concurrent NF-kappaB activation. It is unknown how the protection conveyed by NF-kappaB is overridden during apoptosis. We report here that IkappaB kinase (IKK) beta was specifically proteolyzed by Caspase-3-related caspases at aspartic acid residues 78, 242, 373, and 546 during tumor necrosis factor (TNF)-alpha-induced apoptosis. Proteolysis of IKKbeta eliminated its enzymatic activity, interfered with IKK activation, and promoted TNF-alpha killing. Point mutations that abrogate IKKbeta proteolysis generated a caspase-resistant IKKbeta mutant, which suppressed TNF-alpha-induced apoptosis. Thus, our study demonstrates that TNF-alpha-induced apoptosis requires caspase-mediated proteolysis of IKKbeta.
authors.affiliation: Ben May Institute for Cancer Research, Committee on Cancer Biology, University of Chicago, 5841 South Maryland Avenue, MC 6027, Chicago, IL 60637, USA.
authors.forename: G
authors.initials: G
authors.lastname: Tang
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: Y
authors.initials: Y
authors.lastname: Minemoto
authors.forename: A
authors.initials: A
authors.lastname: Lin
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D006801:Humans; D051550:I-kappa B Kinase; D015151:Immunoblotting; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases