title: Bcr-Abl-mediated protection from apoptosis downstream of mitochondrial cytochrome c release.
abstract: Bcr-Abl, activated in chronic myelogenous leukemias, is a potent cell death inhibitor. Previous reports have shown that Bcr-Abl prevents apoptosis through inhibition of mitochondrial cytochrome c release. We report here that Bcr-Abl also inhibits caspase activation after the release of cytochrome c. Bcr-Abl inhibited caspase activation by cytochrome c added to cell-free lysates and prevented apoptosis when cytochrome c was microinjected into intact cells. Bcr-Abl acted posttranslationally to prevent the cytochrome c-induced binding of Apaf-1 to procaspase 9. Although Bcr-Abl prevented interaction of endogenous Apaf-1 with the recombinant prodomain of caspase 9, it did not affect the association of endogenous caspase 9 with the isolated Apaf-1 caspase recruitment domain (CARD) or Apaf-1 lacking WD-40 repeats. These data suggest that Apaf-1 recruitment of caspase 9 is faulty in the presence of Bcr-Abl and that cytochrome c/dATP-induced exposure of the Apaf-1 CARD is likely defective. These data provide a novel locus of Bcr-Abl antiapoptotic action and suggest a distinct mechanism of apoptosomal inhibition.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Box 3813, Durham, NC 27710, USA.
authors.forename: Paula B
authors.initials: PB
authors.lastname: Deming
authors.forename: Zachary T
authors.initials: ZT
authors.lastname: Schafer
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Tashker
authors.forename: Malia B
authors.initials: MB
authors.lastname: Potts
authors.forename: Mohanish
authors.initials: M
authors.lastname: Deshmukh
authors.forename: Sally
authors.initials: S
authors.lastname: Kornbluth
mesh_terms: D000818:Animals; D017209:Apoptosis; D053477:Apoptotic Protease-Activating Factor 1; D015153:Blotting, Western; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D016044:Fusion Proteins, bcr-abl / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D047468:Immunoprecipitation; D020014:K562 Cells; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D019000:Phosphotyrosine / Q000737:chemistry; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014981:Xenopus
chemical_list: C506592:APAF1 protein, human; C506593:Apaf1 protein, mouse; C506594:Apaf1 protein, rat; D053477:Apoptotic Protease-Activating Factor 1; D011506:Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D019000:Phosphotyrosine; D045304:Cytochromes c; D016044:Fusion Proteins, bcr-abl; C506433:CASP9 protein, human; C506434:Casp9 protein, mouse; C506435:Casp9 protein, rat; D053453:Caspase 9; D020169:Caspases; D005978:Glutathione