betaTrCP- and Rsk1/2-mediated degradation of BimEL inhibits apoptosis

Mol Cell. 2009 Jan 16;33(1):109-16. doi: 10.1016/j.molcel.2008.12.020.


The BimEL tumor suppressor is a potent proapoptotic BH3-only protein. We found that, in response to survival signals, BimEL was rapidly phosphorylated on three serine residues in a conserved degron, facilitating binding and degradation via the F box protein betaTrCP. Phosphorylation of the BimEL degron was executed by Rsk1/2 and promoted by the Erk1/2-mediated phosphorylation of BimEL on Ser69. Compared to wild-type BimEL, a BimEL phosphorylation mutant unable to bind betaTrCP was stabilized and consequently potent at inducing apoptosis by the intrinsic mitochondrial pathway. Moreover, although non-small cell lung cancer (NSCLC) cells often become resistant to gefitinib (a clinically relevant tyrosine kinase inhibitor that induces apoptosis through BimEL), silencing of either betaTrCP or Rsk1/2 resulted in BimEL-mediated apoptosis of both gefitinib-sensitive and gefitinib-insensitive NSCLC cells. Our findings reveal that betaTrCP promotes cell survival in cooperation with the ERK-RSK pathway by targeting BimEL for degradation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins / metabolism*
  • Apoptosis*
  • Bcl-2-Like Protein 11
  • Cell Line
  • Humans
  • Membrane Proteins / metabolism*
  • Mice
  • Protein Processing, Post-Translational*
  • Protein Stability
  • Proto-Oncogene Proteins / metabolism*
  • Ribosomal Protein S6 Kinases, 90-kDa / metabolism*
  • beta-Transducin Repeat-Containing Proteins / metabolism*


  • Apoptosis Regulatory Proteins
  • BCL2L11 protein, human
  • Bcl-2-Like Protein 11
  • Bcl2l11 protein, mouse
  • Membrane Proteins
  • Proto-Oncogene Proteins
  • beta-Transducin Repeat-Containing Proteins
  • RPS6KA1 protein, human
  • Ribosomal Protein S6 Kinases, 90-kDa
  • ribosomal protein S6 kinase, 90kDa, polypeptide 3