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Dab2 stabilizes Axin and attenuates Wnt/beta-catenin signaling by preventing protein phosphatase 1 (PP1)-Axin

Y Jiang1, W Luo, P H Howe

  • 1Department of Cancer Biology NB4, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.

Oncogene
|July 8, 2009
PubMed

Insights

Disabled-2 (Dab2) protein inhibits Wnt/beta-catenin signaling by blocking protein phosphatase 1 (PP1) interaction with Axin. This stabilizes Axin, preventing Wnt pathway activation crucial for embryonic development.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Molecular Signaling

Background:

  • Wnt/beta-catenin signaling is vital for cell proliferation, differentiation, and embryonic development.
  • The endocytic adaptor disabled-2 (Dab2) previously showed potential to attenuate Wnt signaling by stabilizing Axin.
  • Protein phosphatase 1 (PP1) dephosphorylates Axin, leading to its destabilization.

Purpose of the Study:

  • To elucidate the mechanism by which Dab2 inhibits Wnt/beta-catenin signaling.
  • To investigate the interaction between Dab2, Axin, and PP1.
  • To confirm the role of Dab2 in Wnt signaling regulation in vivo.

Main Methods:

  • Co-immunoprecipitation assays to study protein interactions.
  • Western blotting to assess protein levels and phosphorylation.
  • Expression of Dab2 and mutant forms in zebrafish embryos.
  • Analysis of embryonic patterning.

Main Results:

  • Dab2 acts upstream of PP1, preventing PP1-Axin interaction and subsequent Axin dephosphorylation.
  • Dab2 competitively inhibits PP1 binding to Axin by binding to the same Axin C-terminal domain.
  • Dab2 N-terminus binds both PP1 and Axin; a Dab2 N-terminal mutant inhibits PP1-Axin interaction.
  • Ectopic Dab2 expression in zebrafish embryos phenocopies Axin overexpression, altering embryonic patterning.

Conclusions:

  • Dab2 stabilizes Axin by preventing PP1-mediated dephosphorylation.
  • Dab2 attenuates Wnt/beta-catenin signaling through inhibition of the PP1-Axin interaction.
  • Dab2 plays a critical role in regulating Wnt signaling during embryonic development.

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