ER stress-induced apoptosis and caspase-12 activation occurs downstream of mitochondrial apoptosis involving Apaf-1

Hiroshi Shiraishi, Hideaki Okamoto, Akihiko Yoshimura, Hiroki Yoshida

Research output: Contribution to journalArticlepeer-review

125 Citations (Scopus)

Abstract

Accumulation of unfolded proteins induces endoplasmic reticulum (ER) stress. Excessive and prolonged stresses lead cells to apoptosis. However, the precise molecular mechanisms of ER stress-induced apoptosis have not been fully elucidated. We investigated the involvement of the apoptosome in ER stress-induced cell death pathway using mouse embryonic fibroblasts (MEFs) and mice deficient for Apaf-1. Apaf-1-deficient MEFs showed ore resistance to ER stress-inducing reagents as compared with wild type cells. Despite comparable induction of ER stress in both wild type and Apaf-1-deficient cells, activation of caspase-3 was only observed in wild type, but not Apaf-1-deficient, MEFs. Under ER stress conditions, BAX translocated to mitochondria and cytochrome c was released from mitochondria. We also demonstrated that caspase-12 was processed downstream of Apaf-1 and caspase-3, and neither overexpression nor knockdown of caspase-12 affected susceptibility of the cells to ER stress-induced cell death. Furthermore, in the kidneys of Apaf-1-deficient mice, apoptosis induced by in vivo administration of tunicamycin was remarkably suppressed as compared with wild type mice. These data collectively demonstrated that Apaf-1 and the mitochondrial pathway of apoptosis play significant roles in ER stress-induced apoptosis.

Original languageEnglish
Pages (from-to)3958-3966
Number of pages9
JournalJournal of Cell Science
Volume119
Issue number19
DOIs
Publication statusPublished - 2006 Oct 1
Externally publishedYes

Keywords

  • Apaf-1
  • Apoptosis
  • ER stress
  • Mitochondria

ASJC Scopus subject areas

  • Cell Biology

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