Isolation of Ich-1S (caspase-2S)-binding protein that partially inhibits caspase activity.
Members of the caspase family are essential executors of apoptosis. Caspase-2 has two messenger RNAs generated by alternative splicing, which encode caspase-2L and caspase-2S. Although caspase-2L induces apoptosis, caspase-2S also has the ability to antagonize cell death. Experiments in caspase-2-deficient mice showed that caspase-2 functions to delay cell death in some neuronal populations, suggesting that caspase-2S dominantly acts for cell survival in the brain. However, the mechanism of caspase-2S-mediated anti-apoptotic effect is still unclear. Here, we isolated a protein that interacts with caspase-2S, designated as Ich-1S (caspase-2S)-binding protein (ISBP), by yeast two-hybrid screening using full-length caspase-2S cDNA as a bait. ISBP is identical to the recently isolated calcium and integrin-binding protein, and a small molecule calcium-binding protein with two EF-hand motifs of its C-terminus. In vitro transcribed and translated ISBP interacts specifically with glutathione-S-transferase-fused caspase-2S. Moreover, the interaction between ISBP and caspase-2S was observed in cultured cells. Northern blot analysis indicated that ISBP may be a ubiquitous protein. Interestingly, ISBP can partially inhibit the processing of pro-caspase-2L induced by anti-Fas antibody-treated Jurkat cytosolic lysates. These results suggested that ISBP may be the mediator for the survival function of caspase-2S.
Ito
A
A
Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
Uehara
T
T
Nomura
Y
Y
D016475:3T3 Cells; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D053143:Caspase 2; D061945:Caspase Inhibitors; D020169:Caspases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002457:Cell Extracts; D002470:Cell Survival; D003001:Cloning, Molecular; D020832:EF Hand Motifs; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D008970:Molecular Weight; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
C109198:CIB1 protein, human; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D002457:Cell Extracts; C491605:Cib1 protein, mouse; D004792:Enzyme Precursors; D012333:RNA, Messenger; D053143:Caspase 2; D020169:Caspases