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EMBO J. 1999 Apr 15;18(8):2040-8.

Presence of a pre-apoptotic complex of pro-caspase-3, Hsp60 and Hsp10 in the mitochondrial fraction of jurkat cells.

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  • 1Institute of Environmental Medicine, Division of Toxicology, Karolinska Institutet, Box 210, S-171 77, Stockholm, Sweden. afshin.samali@imm.ki.se

Abstract

Activation of pro-caspase-3 is a central event in the execution phase of apoptosis and appears to serve as the convergence point of different apoptotic signaling pathways. Recently, mitochondria were found to play a central role in apoptosis through release of cytochrome c and activation of caspases. Moreover, a sub-population of pro-caspase-3 has been found to be localized to this organelle. In the present study, we demonstrate that pro-caspase-3 is present in the mitochondrial fraction of Jurkat T cells in a complex with the chaperone proteins Hsp60 and Hsp10. Induction of apoptosis with staurosporine led to the activation of mitochondrial pro-caspase-3 and its dissociation from the Hsps which were released from mitochondria. The release of Hsps occurred simultaneously with the release of other mitochondrial intermembrane space proteins including cytochrome c and adenylate kinase, prior to a loss of mitochondrial transmembrane potential. In in vitro systems, recombinant Hsp60 and Hsp10 accelerated the activation of pro-caspase-3 by cytochrome c and dATP in an ATP-dependent manner, consistent with their function as chaperones. This finding suggests that the release of mitochondrial Hsps may also accelerate caspase activation in the cytoplasm of intact cells.

PMID:
10205158
[PubMed - indexed for MEDLINE]
PMCID:
PMC1171288
Free PMC Article
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