DAP5 promotes cap-independent translation of Bcl-2 and CDK1 to facilitate cell survival during mitosis

Mol Cell. 2008 May 23;30(4):447-59. doi: 10.1016/j.molcel.2008.03.018. Epub 2008 May 1.

Abstract

DAP5 is an eIF4G protein previously implicated in mediating cap-independent translation in response to cellular stresses. Here we report that DAP5 is crucial for continuous cell survival in nonstressed cells. The knockdown of endogenous DAP5 induced M phase-specific caspase-dependent apoptosis. Bcl-2 and CDK1 were identified by two independent screens as DAP5 translation targets. Notably, the activity of the Bcl-2 IRES was reduced in DAP5 knockdown cells and a selective shift of Bcl-2 mRNA toward light polysomal fractions was detected. Furthermore, a functional IRES was identified in the 5'UTR of CDK1. At the cellular level, attenuated translation of CDK1 by DAP5 knockdown decreased the phosphorylation of its M phase substrates. Ectopic expression of Bcl-2 or CDK1 proteins partially reduced the extent of caspase activation caused by DAP5 knockdown. Thus, DAP5 is necessary for maintaining cell survival during mitosis by promoting cap-independent translation of at least two prosurvival proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions
  • Animals
  • Apoptosis / physiology
  • CDC2 Protein Kinase / genetics
  • CDC2 Protein Kinase / metabolism*
  • Cell Line
  • Cell Survival
  • Eukaryotic Initiation Factor-4G / genetics
  • Eukaryotic Initiation Factor-4G / metabolism*
  • Humans
  • Mice
  • Mitosis / physiology*
  • Peptide Initiation Factors
  • Polyribosomes / metabolism
  • Protein Biosynthesis*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • RNA Interference

Substances

  • 5' Untranslated Regions
  • EIF4G1 protein, human
  • EIF4G2 protein, human
  • Eukaryotic Initiation Factor-4G
  • Peptide Initiation Factors
  • Proto-Oncogene Proteins c-bcl-2
  • eukaryotic translational regulator p97
  • CDC2 Protein Kinase