title: BCL-2, BCL-X(L) sequester BH3 domain-only molecules preventing BAX- and BAK-mediated mitochondrial apoptosis.
abstract: Critical issues in apoptosis include the importance of caspases versus organelle dysfunction, dominance of anti- versus proapoptotic BCL-2 members, and whether commitment occurs upstream or downstream of mitochondria. Here, we show cells deficient for the downstream effectors Apaf-1, Caspase-9, or Caspase-3 display only transient protection from "BH3 domain-only" molecules and die a caspase-independent death by mitochondrial dysfunction. Cells with an upstream defect, lacking "multidomain" BAX, BAK demonstrate long-term resistance to all BH3 domain-only members, including BAD, BIM, and NOXA. Comparison of wild-type versus mutant BCL-2, BCL-X(L) indicates these antiapoptotics sequester BH3 domain-only molecules in stable mitochondrial complexes, preventing the activation of BAX, BAK. Thus, in mammals, BH3 domain-only molecules activate multidomain proapoptotic members to trigger a mitochondrial pathway, which both releases cytochrome c to activate caspases and initiates caspase-independent mitochondrial dysfunction.
authors.affiliation: Howard Hughes Medical Institute, Harvard Medical School, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
authors.forename: E H
authors.initials: EH
authors.lastname: Cheng
authors.forename: M C
authors.initials: MC
authors.lastname: Wei
authors.forename: S
authors.initials: S
authors.lastname: Weiler
authors.forename: R A
authors.initials: RA
authors.lastname: Flavell
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
authors.forename: T
authors.initials: T
authors.lastname: Lindsten
authors.forename: S J
authors.initials: SJ
authors.lastname: Korsmeyer
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D053477:Apoptotic Protease-Activating Factor 1; D051023:BH3 Interacting Domain Death Agonist Protein; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003574:Cytochrome c Group / Q000378:metabolism; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
chemical_list: C506592:APAF1 protein, human; D051017:Apoptosis Regulatory Proteins; D053477:Apoptotic Protease-Activating Factor 1; C000606775:BCL2L11 protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins; D003574:Cytochrome c Group; D004792:Enzyme Precursors; D008565:Membrane Proteins; C498702:PMAIP1 protein, human; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; D020169:Caspases