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Phosphorylation by the beta-catenin/MAPK complex promotes 14-3-3-mediated nuclear export of TCF/POP-1 in

Miao-Chia Lo1, Frédérique Gay, Raanan Odom

  • 1Department of Molecular Biology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA.

Cell
|April 7, 2004
PubMed

Insights

Wnt/MAPK signaling reduces POP-1 levels in C. elegans embryos by promoting its phosphorylation and nuclear export. This process involves the beta-catenin WRM-1 and MAP kinase LIT-1, ensuring proper cell fate.

Area of Science:

  • Developmental Biology
  • Cell Signaling
  • Molecular Genetics

Background:

  • Wnt/MAPK signaling regulates gene expression via transcription factors like TCF/LEF.
  • In C. elegans embryos, POP-1 (a TCF/LEF factor) levels are dynamically regulated.
  • Beta-catenin WRM-1 is known to be involved in POP-1 downregulation.

Purpose of the Study:

  • To elucidate the molecular mechanism by which WRM-1 downregulates POP-1.
  • To investigate the role of MAP kinase LIT-1 in POP-1 regulation.
  • To understand how Wnt/MAPK signaling controls POP-1 nuclear export.

Main Methods:

  • Genetic analysis in C. elegans.
  • Protein interaction studies.
  • Phosphorylation assays.
  • Subcellular localization studies (nuclear export).

Main Results:

  • WRM-1 mediates POP-1 downregulation by promoting its phosphorylation by LIT-1.
  • Phosphorylated POP-1 is exported from the nucleus via the 14-3-3 protein PAR-5.
  • Wnt/MAPK signaling increases nuclear LIT-1 levels in responsive cells.
  • The beta-catenin-interacting domain of POP-1 is not essential for its downregulation.

Conclusions:

  • Wnt/MAPK signaling downregulates POP-1 by increasing nuclear LIT-1, leading to POP-1 phosphorylation and PAR-5-mediated nuclear export.
  • This mechanism ensures precise control of transcription factor levels during embryonic development.
  • The findings provide a detailed molecular model for Wnt/MAPK-mediated gene regulation in C. elegans.

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