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Constitutively active Ras negatively regulates Erk MAP kinase through induction of MAP kinase phosphatase 3 (MKP3) in

Young Jae Park1, Jong Min Lee2, Soon Young Shin2

  • 1Laboratory of Immunobiology, School of Life Science and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Korea.

BMB Reports
|March 8, 2014
PubMed

Insights

Active Ras signaling can paradoxically inhibit Erk1/2 phosphorylation by upregulating MKP3, a negative regulator. This inhibition is mediated by the PI3K/Akt pathway, highlighting a novel feedback loop in cell signaling.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • The Ras/Raf/MEK/Erk pathway regulates critical cellular processes like growth and apoptosis.
  • Erk MAPK activation is often dysregulated in cancer, but the role of active Ras in modulating Erk activity is not fully understood.

Purpose of the Study:

  • To investigate how active Ras influences Erk1/2 phosphorylation.
  • To elucidate the molecular mechanisms underlying the modulation of Erk activity by Ras.

Main Methods:

  • Overexpression of active H-Ras (H-RasG12R) in NIH3T3 fibroblasts.
  • Analysis of FGF2-induced Erk1/2 phosphorylation.
  • Northern blot analysis to assess MAP kinase phosphatase 3 (MKP3) mRNA expression.
  • Inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway.

Main Results:

  • Overexpression of active H-Ras impaired FGF2-induced Erk1/2 phosphorylation.
  • Prolonged active Ras expression led to increased MKP3 mRNA levels.
  • Inhibition of PI3K/Akt rescued Erk1/2 phosphorylation by abrogating MKP3 up-regulation.

Conclusions:

  • Active Ras negatively regulates the Ras/Raf/MEK/Erk pathway via PI3K/Akt-dependent transcriptional activation of MKP3.
  • MKP3 acts as a crucial mediator in the Ras-induced suppression of Erk MAPK activity.

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