HectD1 E3 ligase modifies adenomatous polyposis coli (APC) with polyubiquitin to promote the APC-axin interaction

J Biol Chem. 2013 Feb 8;288(6):3753-67. doi: 10.1074/jbc.M112.415240. Epub 2012 Dec 31.

Abstract

The adenomatous polyposis coli (APC) protein functions as a negative regulator of the Wnt signaling pathway. In this capacity, APC forms a "destruction complex" with Axin, CK1α, and GSK3β to foster phosphorylation of the Wnt effector β-catenin earmarking it for Lys-48-linked polyubiquitylation and proteasomal degradation. APC is conjugated with Lys-63-linked ubiquitin chains when it is bound to Axin, but it is unclear whether this modification promotes the APC-Axin interaction or confers upon APC an alternative function in the destruction complex. Here we identify HectD1 as a candidate E3 ubiquitin ligase that modifies APC with Lys-63 polyubiquitin. Knockdown of HectD1 diminished APC ubiquitylation, disrupted the APC-Axin interaction, and augmented Wnt3a-induced β-catenin stabilization and signaling. These results indicate that HectD1 promotes the APC-Axin interaction to negatively regulate Wnt signaling.

MeSH terms

  • Adenomatous Polyposis Coli Protein / genetics
  • Adenomatous Polyposis Coli Protein / metabolism*
  • Animals
  • Axin Protein / genetics
  • Axin Protein / metabolism*
  • Gene Knockdown Techniques
  • HEK293 Cells
  • Humans
  • Mice
  • Polyubiquitin / genetics
  • Polyubiquitin / metabolism*
  • Protein Binding
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*
  • Ubiquitination / physiology*
  • Wnt Signaling Pathway / physiology*

Substances

  • APC protein, human
  • Adenomatous Polyposis Coli Protein
  • Axin Protein
  • Polyubiquitin
  • HectD1 protein, human
  • Ubiquitin-Protein Ligases