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H-Ras is degraded by Wnt/beta-catenin signaling via beta-TrCP-mediated polyubiquitylation

Sung-Eun Kim1, Ju-Yong Yoon, Woo-Jeong Jeong

  • 1National Research Laboratory of Molecular Complex Control and Department of Biotechnology, BK21 project for Medical Science, Yonsei University, Seoul 120-749, Korea.

Journal of Cell Science
|February 26, 2009
PubMed

Insights

This study reveals a new way H-Ras protein levels are controlled through ubiquitylation and degradation, influenced by the Wnt/beta-catenin pathway. This discovery offers insights into cancer development and signaling pathway crosstalk.

Area of Science:

  • Molecular Biology
  • Cellular Signaling
  • Oncology

Background:

  • Ras proteins are crucial proto-oncogenes regulated by GDP/GTP exchange.
  • Understanding Ras protein regulation is key to deciphering cellular transformation and cancer.
  • The Wnt/beta-catenin pathway is frequently dysregulated in various cancers.

Purpose of the Study:

  • To elucidate a novel regulatory mechanism controlling H-Ras protein turnover.
  • To investigate the role of beta-TrCP-mediated ubiquitylation and proteasomal degradation in H-Ras stability.
  • To determine the interplay between the Wnt/beta-catenin signaling pathway and Ras protein regulation.

Main Methods:

  • Investigated H-Ras protein turnover using ubiquitylation and proteasomal degradation assays.
  • Utilized co-immunoprecipitation to study H-Ras interaction with beta-TrCP.
  • Employed in vivo studies in mice to assess Ras stability regulation by Wnt3a stimulation.

Main Results:

  • Identified beta-TrCP-mediated ubiquitylation and proteasomal degradation as a novel H-Ras regulatory mechanism.
  • Demonstrated that Axin and adenomatous polyposis coli (Apc) stimulate H-Ras degradation, while Wnt3a inhibits it.
  • Showed that H-Ras-mediated cellular transformation is suppressed by beta-TrCP and/or Axin expression.
  • Confirmed in vivo regulation of Ras stability by Wnt/beta-catenin signaling in mouse intestines.

Conclusions:

  • H-Ras protein stability is dynamically regulated by the Wnt/beta-catenin signaling pathway via beta-TrCP.
  • This regulation provides a mechanistic link between Wnt/beta-catenin and Ras-ERK pathway crosstalk in cellular transformation.
  • The findings offer potential therapeutic targets for cancers involving these signaling pathways.

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