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Molecular association between beta-catenin degradation complex and Rac guanine exchange factor DOCK4 is essential for

G Upadhyay1, W Goessling, T E North

  • 1Department of Medicine, Gastrointestinal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. gu6@georgetown.edu

Oncogene
|July 22, 2008
PubMed

Insights

DOCK4, a Rac GEF, acts as a scaffold protein in the Wnt/beta-catenin pathway. It regulates beta-catenin stability by interacting with the degradation complex, enhancing Wnt signaling in development and disease.

Area of Science:

  • Cellular and Molecular Biology
  • Developmental Biology
  • Cancer Biology

Background:

  • The canonical Wnt/beta-catenin pathway is crucial for development and stem cell renewal.
  • Deregulation of this pathway is linked to increased cell growth and neoplasia.
  • The small GTPase Rac influences Wnt signaling, but the mechanism is unclear.

Purpose of the Study:

  • To investigate the role of DOCK4 in mediating Wnt-induced Rac activation.
  • To elucidate the molecular mechanism by which DOCK4 influences beta-catenin stability.
  • To confirm DOCK4's function in Wnt/beta-catenin signaling in vivo.

Main Methods:

  • Biochemical studies to analyze DOCK4 interaction with the beta-catenin degradation complex.
  • In vitro experiments assessing DOCK4's effect on cellular beta-catenin levels.
  • In vivo studies using a T-cell factor reporter zebrafish model.

Main Results:

  • DOCK4 mediates Wnt-induced Rac activation and regulates cellular beta-catenin levels.
  • DOCK4 interacts with the adenomatosis polyposis coli, Axin, and GSK3beta complex, enhancing beta-catenin stability and Axin degradation.
  • DOCK4 phosphorylation by GSK3beta boosts Wnt-induced Rac activation.
  • DOCK4 is essential for Wnt/beta-catenin activity in zebrafish.

Conclusions:

  • DOCK4 acts as a novel scaffold protein in the Wnt/beta-catenin pathway.
  • DOCK4 links Rac signaling to beta-catenin regulation, providing a new target for therapeutic intervention.
  • This study reveals a novel intracellular signaling mechanism involving DOCK4 in Wnt pathway regulation.

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