In vivo evidence that caspase-3 is required for Fas-mediated apoptosis of hepatocytes.
Caspase-3 is essential for Fas-mediated apoptosis in vitro. We investigated the role of caspase-3 in Fas-mediated cell death in vivo by injecting caspase-3-deficient mice with agonistic anti-Fas Ab. Wild-type controls died rapidly of fulminant hepatitis, whereas the survival of caspase-3-/- mice was increased due to a delay in hepatocyte cell death. Bcl-2 expression in the liver was dramatically decreased in wild-type mice following anti-Fas injection, but was unchanged in caspase-3-/- mice. Hepatocytes from anti-Fas-injected wild-type, but not caspase-3-/-, mice released cytochrome c into the cytoplasm. Western blotting confirmed the lack of caspase-3-mediated cleavage of Bcl-2. Presumably the presence of intact Bcl-2 in caspase-3-/- hepatocytes prevents the release of cytochrome c from the mitochondria, a required step for the mitochondrial death pathway. We also show by Western blot that Bcl-xL, caspase-9, caspase-8, and Bid are processed by caspase-3 in injected wild-type mice but that this processing does not occur in caspase-3-/- mice. This study thus provides novel in vivo evidence that caspase-3, conventionally known for its downstream effector function in apoptosis, also modifies Bcl-2 and other upstream proteins involved in the regulation of Fas-mediated apoptosis.
Woo
M
M
Amgen Institute, Ontario Cancer Institute, University of Toronto, Canada.
Hakem
A
A
Elia
A J
AJ
Hakem
R
R
Duncan
G S
GS
Patterson
B J
BJ
Mak
T W
TW
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D017209:Apoptosis / Q000276:immunology*; D053148:Caspase 3; D020169:Caspases / Q000235:genetics / Q000502:physiology*; D003574:Cytochrome c Group / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D007274:Injections, Intraperitoneal; D008099:Liver / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011499:Protein Processing, Post-Translational / Q000276:immunology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D013194:Staining and Labeling; D016019:Survival Analysis; D019014:fas Receptor / Q000276:immunology / Q000502:physiology*
D000911:Antibodies, Monoclonal; D003574:Cytochrome c Group; D019253:Proto-Oncogene Proteins c-bcl-2; D019014:fas Receptor; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases