Tunicamycin-induced ER stress upregulates the expression of mitochondrial HtrA2 and promotes apoptosis through the cytosolic release of HtrA2

Chul Han, Min Kyung Nam, Hyo Jin Park, Young Mo Seong, Seongman Kang, Hyangshuk Rhim

Research output: Contribution to journalArticle

33 Citations (Scopus)


Recent studies provide some evidence that the HtrA2 protein is intimately associated with the pathogenesis of neurodegenerative disorders and that endoplasmic reticulum (ER) quality control and ER stress-associated cell death play critical roles in neuronal cell death. However, little is known about the intimate relationship between HtrA2 and ER stress-associated cellular responses. In the present study, we have demonstrated that the HtrA2 protein level was gradually and significantly increased by up to 10-fold in the mitochondria under tunicamycin (Tm)-induced ER stress, which eventually promoted cell death through the release of HtrA2 into the cytoplasm. Using an ecdysone-inducible mammalian expression system, we demonstrate that the extent of cell death in 293-HtrA2 cells was approximately 20 times higher under Tm-induced ER stress, indicating that the increase in the HtrA2 protein level in the mitochondria itself is necessary but not sufficient for the promotion of cell death. Taken together, these results suggest that HtrA2 may serve as a mediator of ER stress-induced apoptosis and ER-mitochondrial cross-talk in some cellular processes.

Original languageEnglish
Pages (from-to)1197-1202
Number of pages6
JournalJournal of microbiology and biotechnology
Issue number6
Publication statusPublished - 2008 Jun 1



  • Apoptosis
  • ER stress
  • HtrA2
  • Tunicamycin

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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