The mitochondrial serine protease HtrA2/Omi cleaves RIP1 during apoptosis of Ba/F3 cells induced by growth factor withdrawal

Cell Res. 2010 Apr;20(4):421-33. doi: 10.1038/cr.2010.18. Epub 2010 Feb 2.


Interleukin-3 (IL-3) deprivation of the mouse pro-B cell line Ba/F3 induces cell death that is abrogated by B-cell lymphoma 2 (Bcl-2) overexpression, but remains unaffected by the pan-caspase inhibitor carbobenzoxy-valyl-analyl-aspartyl-[O-methyl]-fluoromethylketone (zVAD-fmk). IL-3 withdrawal causes receptor-interacting protein (RIP)1 cleavage into C-terminal fragments of 30 and 25 kDa, and only cleavage leading to the former was prevented by zVAD-fmk. siRNA experiments demonstrated that generation of the 25-kDa fragment was due to a Bcl-2-modulated release of the mitochondrial serine protease high temperature requirement protein A2 (HtrA2)/Omi. Accordingly, recombinant HtrA2/Omi efficiently cleaved mouse RIP1 in vitro, generating fragments matching those observed in IL-3-deprived Ba/F3 cells. The HtrA2/Omi cleavage site in mouse RIP1 was mapped to the intermediate domain and the corresponding N- and C-terminal fragments were impaired in their ability to activate nuclear factor-kappaB, c-Jun N-terminal kinase and p38 mitogen-activated protein kinase. Interestingly, knockdown of HtrA2/Omi afforded protection against IL-3 withdrawal-induced death in the presence of zVAD-fmk, demonstrating a role for HtrA2/Omi in caspase-independent cell death during growth factor withdrawal by cleaving RIP1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Chloromethyl Ketones / pharmacology
  • Animals
  • Apoptosis*
  • Caspases / metabolism
  • Cell Line
  • High-Temperature Requirement A Serine Peptidase 2
  • Interleukin-3 / pharmacology
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Mice
  • Mitochondria / enzymology*
  • Mitochondrial Proteins / metabolism*
  • NF-kappa B / metabolism
  • Precursor Cells, B-Lymphoid / immunology
  • Precursor Cells, B-Lymphoid / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Receptor-Interacting Protein Serine-Threonine Kinases / metabolism*
  • Serine Endopeptidases / metabolism*
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Amino Acid Chloromethyl Ketones
  • Interleukin-3
  • Mitochondrial Proteins
  • NF-kappa B
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Serine Endopeptidases
  • High-Temperature Requirement A Serine Peptidase 2
  • Htra2 protein, mouse
  • Caspases