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Bcl-2 prolongs cell survival after Bax-induced release of cytochrome c.

Author	T Rossé, R Olivier, L Monney, M Rager, S Conus, I Fellay, B Jansen, C Borner, T Rossé, R Olivier, L Monney, M Rager, S Conus, I Fellay, B Jansen, C Borner
Citation Information	Nature, 391:496-9 (1998)
Keywords	Animals, Apoptosis, Caspase 3, Caspases, Cell Survival, Cells, Cultured, Cysteine Endopeptidases, Cysteine Proteinase Inhibitors, Cytochrome c Group, DNA Fragmentation, Enzyme Activation, Humans, Mitochondria, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Rats, Transfection, Tumor Cells, Cultured, bcl-2-Associated X Protein
Applications	Immunocytochemistry (cells)
Related Products	06-499
Pub Med ID	9461218

Following exposure of cells to stimuli that trigger programmed cell death (apoptosis), cytochrome c is rapidly released from mitochondria into the cytoplasm where it activates proteolytic molecules known as caspases that specifically cleave the amino-acid sequence DEVD and are crucial for the execution of apoptosis. The protein Bcl-2 interferes with this activation of caspases by preventing the release of cytochrome c. Here we study these molecular interactions during apoptosis induced by the protein Bax, a pro-apoptotic homologue of Bcl-2. We show that in cells transiently transfected with bax, Bax localizes to mitochondria and induces the release of cytochrome c, activation of caspase-3, membrane blebbing, nuclear fragmentation, and cell death. Caspase inhibitors do not affect Bax-induced cytochrome c release but block caspase-3 activation and nuclear fragmentation. Unexpectedly, Bcl-2 also fails to prevent Bax-induced cytochrome c release, although it co-localizes with Bax to mitochondria. Cells overexpressing both Bcl-2 and Bax show no signs of caspase activation and survive with significant amounts of cytochrome c in the cytoplasm. These findings indicate that Bcl-2 can interfere with Bax killing downstream of and independently of cytochrome c release.