E1a gene expression blocks the ERK1/2 signaling pathway by promoting nuclear localization and MKP up-regulation: implication in v-H-Ras-induced senescence

J Biol Chem. 2008 May 9;283(19):13450-8. doi: 10.1074/jbc.M709230200. Epub 2008 Mar 3.

Abstract

In response to oncogenic signals, cells have developed safe mechanisms to avoid transformation through activation of a senescence program. Upon v-H-Ras overexpression, normal cells undergo senescence through several cellular processes, including activation of the ERK1/2 pathway. Interestingly, the E1a gene from adenovirus 5 has been shown to rescue cells from senescence by a yet unknown mechanism. We investigated whether E1a was able to interfere with the ERK1/2 signaling pathway to rescue cells from v-H-Ras-mediated senescence. Our results show that, E1a overexpression blocks v-H-Ras-mediated ERK1/2 activation by two different and concomitant mechanisms. E1a through its ability to interfere with PKB/Akt activation induces the down-regulation of the PEA15 protein, an ERK1/2 nuclear export factor, leading to nuclear accumulation of ERK1/2. In addition to this, we show that E1a increases the expression of the inducible ERK1/2 nuclear phosphatases (MAPK phosphatases) MKP1/DUSP1 and DUSP5, which leads to ERK1/2 dephosphorylation. We confirmed our observations in the human normal diploid fibroblasts IMR90, in which we could also show that an E1a mutant, unable to bind retinoblastoma protein (pRb), cannot rescue cells from v-H-Ras-induced senescence. In conclusion, E1a is able to rescue from Ras-induced senescence by affecting ERK1/2 localization and phosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Adenovirus E1A Proteins / genetics
  • Adenovirus E1A Proteins / metabolism*
  • Animals
  • Cell Line
  • Cell Nucleus / enzymology
  • Cellular Senescence / physiology
  • Chlorocebus aethiops
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Down-Regulation
  • Enzyme Activation
  • Gene Expression Regulation
  • Humans
  • MAP Kinase Signaling System*
  • Mitogen-Activated Protein Kinase 1 / genetics
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / genetics
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • Mitogen-Activated Protein Kinase Phosphatases / metabolism*
  • Oncogene Protein p21(ras) / genetics
  • Oncogene Protein p21(ras) / metabolism*
  • Protein Binding
  • Retinoblastoma Protein / metabolism
  • Serum
  • Up-Regulation*

Substances

  • Adenovirus E1A Proteins
  • Retinoblastoma Protein
  • Cyclic AMP-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinase Phosphatases
  • Oncogene Protein p21(ras)