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IAPs block apoptotic events induced by caspase‐8 and cytochrome c by direct inhibition of distinct caspases
Author(s) -
Deveraux Quinn L.,
Roy Natalie,
Stennicke Henning R.,
Van Arsdale Todd,
Zhou Qiao,
Srinivasula Srinivasa M.,
Alnemri Emad S.,
Salvesen Guy S.,
Reed John C.
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.8.2215
Subject(s) - xiap , caspase , biology , microbiology and biotechnology , cytochrome c , proteases , inhibitor of apoptosis , apoptosis , intrinsic apoptosis , inhibitor of apoptosis domain , nlrp1 , caspase 9 , apoptosome , caspase 2 , caspase 10 , caspase 8 , caspase 7 , caspase 3 , programmed cell death , biochemistry , mitochondrion , enzyme
Inhibitor of apoptosis (IAP) gene products play an evolutionarily conserved role in regulating programmed cell death in diverse species ranging from insects to humans. Human XIAP, cIAP1 and cIAP2 are direct inhibitors of at least two members of the caspase family of cell death proteases: caspase‐3 and caspase‐7. Here we compared the mechanism by which IAPs interfere with activation of caspase‐3 and other effector caspases in cytosolic extracts where caspase activation was initiated by caspase‐8, a proximal protease activated by ligation of TNF‐family receptors, or by cytochrome c , which is released from mitochondria into the cytosol during apoptosis. These studies demonstrate that XIAP, cIAP1 and cIAP2 can prevent the proteolytic processing of pro‐caspases ‐3, ‐6 and ‐7 by blocking the cytochrome c ‐induced activation of pro‐caspase‐9. In contrast, these IAP family proteins did not prevent caspase‐8‐induced proteolytic activation of pro‐caspase‐3; however, they subsequently inhibited active caspase‐3 directly, thus blocking downstream apoptotic events such as further activation of caspases. These findings demonstrate that IAPs can suppress different apoptotic pathways by inhibiting distinct caspases and identify pro‐caspase‐9 as a new target for IAP‐mediated inhibition of apoptosis.