Bcl-2 cleavages at two adjacent sites by different caspases promote cisplatin-induced apoptosis.
The protein encoded by bcl-2 proto-oncogene plays an important role in the mitochondria-mediated apoptotic pathway. Although the general role of Bcl-2 is anti-apoptotic, previous work showed that Bcl-2 fragments cleaved by caspases could promote apoptotic process. We report herein that Bcl-2 protein was cleaved to produce two fragments of around 23 kDa in human hepatocarcinoma BEL-7404 cells or in Bcl-2 overexpressing CHO cells induced by cisplatin. Treating cells with the general caspase inhibitor z-VAD-fmk blocked the induced cleavage of Bcl-2. Mutagenesis analyses showed that Bcl-2 was cleaved by caspases at two adjacent recognition sites in the loop domain (YEWD(31) decrease AGD(34) decrease V), which could be inhibited by caspase-8 and -3 inhibitors, respectively. Overexpression of the carboxyl terminal 23 kDa fragments increased the sensitivity of CHO cells to cisplatin-induced apoptosis. These results indicate that Bcl-2 can be cleaved into two close fragments by different caspases during cisplatin-induced apoptosis, both of which contribute to the acceleration of apoptotic process.
Zhu
Jianbei
J
Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
Yang
Ying
Y
Wu
Jiarui
J
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016466:CHO Cells; D053148:Caspase 3 / Q000378:metabolism*; D053181:Caspase 8 / Q000378:metabolism*; D061945:Caspase Inhibitors; D002945:Cisplatin / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D010446:Peptide Fragments / Q000494:pharmacology; D000090063:Proto-Oncogene Mas; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism* / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; C000715470:MAS1 protein, human; D010446:Peptide Fragments; D000090063:Proto-Oncogene Mas; D019253:Proto-Oncogene Proteins c-bcl-2; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D053148:Caspase 3; D053181:Caspase 8; D002945:Cisplatin