Caenorhabditis elegans caspase homolog CSP-2 inhibits CED-3 autoactivation and apoptosis in germ cells

X. Geng, Q. H. Zhou, E. Kage-Nakadai, Y. Shi, N. Yan, S. Mitani, D. Xue

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


In Caenorhabditis elegans, apoptosis in germ cells is mediated by the same core apoptotic machinery that controls apoptosis in somatic cells. These include the CED-3 caspase, the CED-3 activator CED-4, and the cell death inhibitor CED-9. However, germline apoptosis also differs from somatic apoptosis in its regulation. We found that CSP-3, a caspase homolog that blocks CED-3 autoactivation and apoptosis in somatic cells, does not affect apoptosis in germ cells. Interestingly, the second C. elegans caspase homolog, CSP-2, shares sequence similarity to both catalytic subunits of the CED-3 caspase, and surprisingly, contains a stretch of sequence that is almost identical to that of CSP-3. Unlike CSP-3 that acts specifically in somatic cells, loss of CSP-2 causes increased apoptosis only in germ cells, suggesting that CSP-2 is a germ cell-specific apoptosis inhibitor. Moreover, like CSP-3, CSP-2 associates with the CED-3 zymogen and inhibits its autoactivation, but does not inhibit CED-4-induced CED-3 activation or the activity of the activated CED-3 protease. Thus, two different C. elegans caspase homologs use the same mechanism to prevent caspase autoactivation and apoptosis in different tissues, suggesting that this could be a generally applicable strategy for regulating caspase activation and apoptosis.

Original languageEnglish (US)
Pages (from-to)1385-1394
Number of pages10
JournalCell Death and Differentiation
Issue number10
StatePublished - 2009

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology


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