Engrailed-1 negatively regulates beta-catenin transcriptional activity by destabilizing beta-catenin via a glycogen synthase kinase-3beta-independent pathway

Mol Biol Cell. 2006 Jun;17(6):2572-80. doi: 10.1091/mbc.e06-01-0052. Epub 2006 Mar 29.

Abstract

The Wnt signaling pathway plays a major role in development, and upon deregulation it is implicated in neoplasia. The hallmark of the canonical Wnt signal is the protection of beta-catenin from ubiquitination and proteasomal degradation induced by glycogen synthase kinase (GSK)-3beta inhibition. The stabilized beta-catenin translocates to the nucleus where it binds to T-cell factor/lymphoid enhancer factor (TCF/LEF) transcription factors, activating the expression of Wnt target genes. In the absence of Wnt signal, TCF/LEF bind to Groucho (Gro)/TLE corepressors and repress Wnt target genes. Gro/TLE bind also to Engrailed (En) transcription factors mediating En-repressive activity on En target genes. Here, we present data suggesting that En-1 serves also as a negative regulator of beta-catenin transcriptional activity; however, its repressive effect is independent of Gro/TLE. Our data suggest that En-1 acts by destabilizing beta-catenin via a proteasomal degradation pathway that is GSK-3beta-independent. Moreover, because En-1-mediated beta-catenin degradation is also Siah independent, our data imply that En-1 exerts its repressive effect by a novel mechanism negatively controlling the level of beta-catenin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Blotting, Northern
  • Cell Line
  • Cloning, Molecular
  • DNA Primers
  • Gene Expression Regulation
  • Glycogen Synthase Kinase 3 / metabolism*
  • Glycogen Synthase Kinase 3 beta
  • Homeodomain Proteins / physiology*
  • Humans
  • Molecular Sequence Data
  • Proteasome Endopeptidase Complex / metabolism
  • Recombinant Proteins / metabolism
  • Transcription, Genetic*
  • Ubiquitin / metabolism
  • beta Catenin / genetics*

Substances

  • DNA Primers
  • EN1 protein, human
  • Homeodomain Proteins
  • Recombinant Proteins
  • Ubiquitin
  • beta Catenin
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Glycogen Synthase Kinase 3
  • Proteasome Endopeptidase Complex