Sequential caspase-2 and caspase-8 activation upstream of mitochondria during ceramide- and etoposide-induced apoptosis

Chiou Feng Lin, Chia Ling Chen, Wen Tsan Chang, Ming Shiou Jan, Li Jin Hsu, Ren Huang Wu, Ming Jer Tang, Wen Chang Chang, Yee Shin Lin

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

Recently, caspase-2 was shown to act upstream of mitochondria in stress-induced apoptosis. Activation of caspase-8, a key event in death receptor-mediated apoptosis, also has been demonstrated in death receptor-independent apoptosis. The regulation of these initiator caspases, which trigger the mitochondrial apoptotic pathway, is unclear. Here we report a potential regulatory role of caspase-2 on caspase-8 during ceramide-induced apoptosis. Our results demonstrate the sequential events of initiator caspase-2 and caspase-8 activation, Bid cleavage and translocation, and mitochondrial damage followed by downstream caspase-9 and -3 activation and cell apoptosis after ceramide induction in T cell lines. The expression of truncated Bid (tBid) and the reduction in mitochondrial transmembrane potential were blocked by caspase-2 or caspase-8, but not caspase-3, knockdown using an RNA interference technique. Ceramide-induced caspase-8 activation, mitochondrial damage, and apoptosis were blocked in caspase-2 short interfering RNA-expressing cells. Therefore, caspase-2 acts upstream of caspase-8 during ceramide-induced mitochondrial apoptosis. Similarly, sequential caspase-2 and caspase-8 activation upstream of mitochondria was also observed in etoposide-induced apoptosis. These data suggest sequential initiator caspase-2 and caspase-8 activation in the mitochondrial apoptotic pathway induced by ceramide or etoposide.

Original languageEnglish
Pages (from-to)40755-40761
Number of pages7
JournalJournal of Biological Chemistry
Volume279
Issue number39
DOIs
Publication statusPublished - 2004 Sep 24

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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