Interaction between Hhex and SOX13 modulates Wnt/TCF activity

J Biol Chem. 2010 Feb 19;285(8):5726-37. doi: 10.1074/jbc.M109.046649. Epub 2009 Dec 22.

Abstract

Fine-tuning of the Wnt/TCF pathway is crucial for multiple embryological processes, including liver development. Here we describe how the interaction between Hhex (hematopoietically expressed homeobox) and SOX13 (SRY-related high mobility group box transcription factor 13), modulates Wnt/TCF pathway activity. Hhex is a homeodomain factor expressed in multiple endoderm-derived tissues, like the liver, where it is essential for proper development. The pleiotropic expression of Hhex during embryonic development and its dual role as a transcriptional repressor and activator suggest the presence of different tissue-specific partners capable of modulating its activity and function. While searching for developmentally regulated Hhex partners, we set up a yeast two-hybrid screening using an E9.5-10.5 mouse embryo library and the N-terminal domain of Hhex as bait. Among the putative protein interactors, we selected SOX13 for further characterization. We found that SOX13 interacts directly with full-length Hhex, and we delineated the interaction domains within the two proteins. SOX13 is known to repress Wnt/TCF signaling by interacting with TCF1. We show that Hhex is able to block the SOX13-dependent repression of Wnt/TCF activity by displacing SOX13 from the SOX13 x TCF1 complex. Moreover, Hhex de-repressed the Wnt/TCF pathway in the ventral foregut endoderm of cultured mouse embryos electroporated with a SOX13-expressing plasmid. We conclude that the interaction between Hhex and SOX13 may contribute to control Wnt/TCF signaling in the early embryo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autoantigens / genetics
  • Autoantigens / metabolism*
  • Cell Line
  • Embryo, Mammalian / embryology
  • Embryonic Development / physiology
  • Endoderm / embryology
  • Hepatocyte Nuclear Factor 1-alpha / genetics
  • Hepatocyte Nuclear Factor 1-alpha / metabolism*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Humans
  • Liver / embryology*
  • Mice
  • SOXD Transcription Factors / genetics
  • SOXD Transcription Factors / metabolism*
  • Saccharomyces cerevisiae
  • Signal Transduction / physiology*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Two-Hybrid System Techniques
  • Wnt Proteins / genetics
  • Wnt Proteins / metabolism*

Substances

  • Autoantigens
  • HHEX protein, human
  • HNF1A protein, human
  • Hepatocyte Nuclear Factor 1-alpha
  • Hhex protein, mouse
  • Hnf1a protein, mouse
  • Homeodomain Proteins
  • SOX13 protein, human
  • SOXD Transcription Factors
  • Sox13 protein, mouse
  • Transcription Factors
  • Wnt Proteins