Generation and characterization of Smac/DIABLO-deficient mice.
The mitochondrial proapoptotic protein Smac/DIABLO has recently been shown to potentiate apoptosis by counteracting the antiapoptotic function of the inhibitor of apoptosis proteins (IAPs). In response to apoptotic stimuli, Smac is released into the cytosol and promotes caspase activation by binding to IAPs, thereby blocking their function. These observations have suggested that Smac is a new regulator of apoptosis. To better understand the physiological function of Smac in normal cells, we generated Smac-deficient (Smac(-/-)) mice by using homologous recombination in embryonic stem (ES) cells. Smac(-/-) mice were viable, grew, and matured normally and did not show any histological abnormalities. Although the cleavage in vitro of procaspase-3 was inhibited in lysates of Smac(-/-) cells, all types of cultured Smac(-/-) cells tested responded normally to all apoptotic stimuli applied. There were also no detectable differences in Fas-mediated apoptosis in the liver in vivo. Our data strongly suggest the existence of a redundant molecule or molecules capable of compensating for a loss of Smac function.
Okada
Hitoshi
H
Amgen Institute and Ontario Cancer Institute, University of Toronto, Toronto, Ontario, Canada M5G 2C1.
Suh
Woong-Kyung
WK
Jin
Jianping
J
Woo
Minna
M
Du
Chunying
C
Elia
Andrew
A
Duncan
Gordon S
GS
Wakeham
Andrew
A
Itie
Annick
A
Lowe
Scott W
SW
Wang
Xiaodong
X
Mak
Tak W
TW
D000818:Animals; D000906:Antibodies / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D001402:B-Lymphocytes / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000502:physiology; D004789:Enzyme Activation; D018390:Gene Targeting; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018345:Mice, Knockout; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D015996:Survival Rate; D013601:T-Lymphocytes / Q000502:physiology; D019014:fas Receptor / Q000378:metabolism
D000906:Antibodies; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C412403:DIABLO protein, human; C499605:Diablo protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D019014:fas Receptor; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; C505409:Casp3 protein, mouse; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases