PINCH-1 promotes Bcl-2-dependent survival signalling and inhibits JNK-mediated apoptosis in the primitive endoderm

J Cell Sci. 2012 Nov 1;125(Pt 21):5233-40. doi: 10.1242/jcs.112029. Epub 2012 Sep 3.

Abstract

The focal adhesion (FA) protein PINCH-1 is required for the survival of primitive endoderm (PrE) cells. How PINCH-1 regulates this fundamental process is not known. Here, we use embryoid bodies (EBs) and isolated EB-derived PrE cells to investigate the mechanisms by which PINCH-1 promotes PrE survival. We report that loss of PINCH-1 in PrE cells leads to a sustained activity of JNK and the pro-apoptotic factor Bax. Mechanistically, the sustained JNK activation was due to diminished levels of the JNK inhibitory factor Ras suppressor protein-1 (RSU-1), whose stability was severely reduced upon loss of PINCH-1. Chemical inhibition of JNK attenuated apoptosis of PrE cells but failed to reduce Bax activity. The increased Bax activity was associated with reduced integrin signalling and diminished Bcl-2 levels, which were shown to inhibit Bax. Altogether our findings show that PINCH-1 is a pro-survival factor that prevents apoptosis of PrE cells by modulating two independent signalling pathways; PINCH-1 inhibits JNK-mediated apoptosis by stabilising the PINCH-1 binding protein RSU-1 and promotes Bcl-2-dependent pro-survival signalling downstream of integrins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Adaptor Proteins, Signal Transducing / physiology
  • Animals
  • Apoptosis*
  • Cell Differentiation
  • Cell Survival
  • Cells, Cultured
  • Embryoid Bodies / cytology
  • Embryoid Bodies / metabolism
  • Endoderm / cytology*
  • Endoderm / metabolism
  • Enzyme Activation
  • Gene Deletion
  • Integrins / metabolism
  • JNK Mitogen-Activated Protein Kinases / metabolism*
  • LIM Domain Proteins / genetics
  • LIM Domain Proteins / metabolism*
  • LIM Domain Proteins / physiology
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Membrane Proteins / physiology
  • Mice
  • Protein Stability
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Transcription Factors / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Integrins
  • LIM Domain Proteins
  • Lims1 protein, mouse
  • Membrane Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Rsu1 protein, mouse
  • Transcription Factors
  • JNK Mitogen-Activated Protein Kinases