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EMBO J 1997 Aug 01;1615:4639-49. doi: 10.1093/emboj/16.15.4639.
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Cytochrome c activation of CPP32-like proteolysis plays a critical role in a Xenopus cell-free apoptosis system.

Kluck RM , Martin SJ , Hoffman BM , Zhou JS , Green DR , Newmeyer DD .

In a cell-free system based on Xenopus egg extracts, Bcl-2 blocks apoptotic activity by preventing cytochrome c release from mitochondria. We now describe in detail the crucial role of cytochrome c in this system. The mitochondrial fraction, when incubated with cytosol, releases cytochrome c. Cytochrome c in turn induces the activation of protease(s) resembling caspase-3 (CPP32), leading to downstream apoptotic events, including the cleavage of fodrin and lamin B1. CPP32-like protease activity plays an essential role in this system, as the caspase inhibitor, Ac-DEVD-CHO, strongly inhibited fodrin and lamin B1 cleavage, as well as nuclear morphology changes. Cytochrome c preparations from various vertebrate species, but not from Saccharomyces cerevisiae, were able to initiate all signs of apoptosis. Cytochrome c by itself was unable to process the precursor form of CPP32; the presence of cytosol was required. The electron transport activity of cytochrome c is not required for its pro-apoptotic function, as Cu- and Zn-substituted cytochrome c had strong pro-apoptotic activity, despite being redox-inactive. However, certain structural features of the molecule were required for this activity. Thus, in the Xenopus cell-free system, cytosol-dependent mitochondrial release of cytochrome c induces apoptosis by activating CPP32-like caspases, via unknown cytosolic factors.

PubMed ID: 9303308
PMC ID: PMC1170090
Article link: EMBO J
Grant support: [+]

Species referenced: Xenopus
Genes referenced: bcl2 casp3.2 lmnb1

References [+] :
Alnemri, Human ICE/CED-3 protease nomenclature. 1996, Pubmed