Resistance to Fas-mediated apoptosis: activation of caspase 3 is regulated by cell cycle regulator p21WAF1 and IAP gene family ILP.
The death receptor Fas transduces apoptotic death signaling mediated by caspases. In the present study, human hepatoma HepG2 cells showed the Fas-mediated apoptosis mediated by caspase, especially caspase 3, only in the presence of actinomycin D. Interestingly, cytosolic proteins extracted from intact HepG2 cells induced caspase 3 inactivation. Our results reveal that this inactivation was triggered by the direct inhibition of activated caspase 3 by IAP gene family ILP. In addition, a 53 kDa protein was co-immunoprecipitated with anti-human caspase 3 antibody from intact HepG2 cells. This protein was a complex-protein of procaspase 3 and the cell cycle regulator p21WAF1 (p21). P21 bound to only procaspase 3, but not to activated caspase 3. We also demonstrate that p21 protein-loaded HepG2 cells resist to Fas-mediated apoptosis even in the presence of actinomycin D. Here we report that caspase 3 inactivation for the resistance to Fas-mediated apoptosis is induced by a procaspase 3/p21 complex formation and direct inhibition of activated caspase 3 by ILP.
Suzuki
A
A
Drug Safety Research Laboratory, Daiichi Pharmaceutical Co., Ltd., Tokyo R&D Center, Japan.
Tsutomi
Y
Y
Akahane
K
K
Araki
T
T
Miura
M
M
D000911:Antibodies, Monoclonal / Q000502:physiology; D017209:Apoptosis / Q000276:immunology / Q000502:physiology*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000473:pathology; D053148:Caspase 3; D020169:Caspases; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D003546:Cysteine Endopeptidases / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000276:immunology / Q000378:metabolism / Q000502:physiology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D005810:Multigene Family; D011233:Precipitin Tests; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D014407:Tumor Cells, Cultured; D051636:X-Linked Inhibitor of Apoptosis Protein; D019014:fas Receptor / Q000276:immunology / Q000502:physiology*
D000911:Antibodies, Monoclonal; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D015853:Cysteine Proteinase Inhibitors; D004792:Enzyme Precursors; D051034:Inhibitor of Apoptosis Proteins; D011506:Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D019014:fas Receptor; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases