Caspase-2-induced apoptosis requires bid cleavage: a physiological role for bid in heat shock-induced death.
The mechanisms through which Caspase-2 leads to cell death are controversial. Here we show, using a combination of cell-free and cell culture-based approaches, that cleavage of the Bcl-2-family protein Bid is required for the induction of apoptosis by Caspase-2. Caspase-2 promoted cytochrome c release from mitochondria in the presence of cytosol from wild-type, but not Bid-deficient, mouse embryonic fibroblasts (MEFs). Recombinant wild-type Bid, but not a noncleavable mutant (D59E), restored cytochrome c release. Similarly, Bid-null MEFs were relatively resistant to apoptosis triggered by active Caspase-2, and apoptosis was restored in Bid-null cells by the expression of wild-type, but not D59E, Bid. Finally, Bid-null MEFs were substantially more resistant to apoptosis induced by heat shock, which has been shown to be dependent on apical activation of Caspase-2. The data are consistent with a model in which Caspase-2 induces apoptosis via cleavage of Bid at D59 and the subsequent engagement of the mitochondrial (intrinsic) pathway.
Department of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, CA 92121, USA.
Christine
C
Bonzon
Lisa
L
Bouchier-Hayes
Lisa J
LJ
Pagliari
Douglas R
DR
Green
Donald D
DD
Newmeyer
D000818:Animals; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein / Q000235:genetics / Q000378:metabolism*; D053143:Caspase 2; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D006358:Hot Temperature; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D009154:Mutation
D051023:BH3 Interacting Domain Death Agonist Protein; C494815:Bid protein, mouse; D045304:Cytochromes c; D053143:Caspase 2; D020169:Caspases