KCTD1 suppresses canonical Wnt signaling pathway by enhancing β-catenin degradation

PLoS One. 2014 Apr 15;9(4):e94343. doi: 10.1371/journal.pone.0094343. eCollection 2014.

Abstract

The canonical Wnt signaling pathway controls normal embryonic development, cellular proliferation and growth, and its aberrant activity results in human carcinogenesis. The core component in regulation of this pathway is β-catenin, but molecular regulation mechanisms of β-catenin stability are not completely known. Here, our recent studies have shown that KCTD1 strongly inhibits TCF/LEF reporter activity. Moreover, KCTD1 interacted with β-catenin both in vivo by co-immunoprecipitation as well as in vitro through GST pull-down assays. We further mapped the interaction regions to the 1-9 armadillo repeats of β-catenin and the BTB domain of KCTD1, especially Position Ala-30 and His-33. Immunofluorescence analysis indicated that KCTD1 promotes the cytoplasmic accumulation of β-catenin. Furthermore, protein stability assays revealed that KCTD1 enhances the ubiquitination/degradation of β-catenin in a concentration-dependent manner in HeLa cells. And the degradation of β-catenin mediated by KCTD1 was alleviated by the proteasome inhibitor, MG132. In addition, KCTD1-mediated β-catenin degradation was dependent on casein kinase 1 (CK1)- and glycogen synthase kinase-3β (GSK-3β)-mediated phosphorylation and enhanced by the E3 ubiquitin ligase β-transducin repeat-containing protein (β-TrCP). Moreover, KCTD1 suppressed the expression of endogenous Wnt downstream genes and transcription factor AP-2α. Finally, we found that Wnt pathway member APC and tumor suppressor p53 influence KCTD1-mediated downregulation of β-catenin. These results suggest that KCTD1 functions as a novel inhibitor of Wnt signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't
  • Retracted Publication

MeSH terms

  • Adenomatous Polyposis Coli Protein / metabolism
  • Amino Acid Sequence
  • Casein Kinase I / metabolism
  • Co-Repressor Proteins
  • Down-Regulation
  • Genes, Reporter / genetics
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Molecular Sequence Data
  • Phosphorylation
  • Plasmids / genetics
  • Proteasome Endopeptidase Complex / metabolism
  • Proteolysis*
  • Repressor Proteins / chemistry
  • Repressor Proteins / metabolism*
  • Transcription, Genetic
  • Tumor Suppressor Protein p53 / metabolism
  • Wnt Signaling Pathway*
  • beta Catenin / metabolism*
  • beta-Transducin Repeat-Containing Proteins / metabolism

Substances

  • APC protein, human
  • Adenomatous Polyposis Coli Protein
  • Co-Repressor Proteins
  • KCTD1 protein, human
  • Repressor Proteins
  • Tumor Suppressor Protein p53
  • beta Catenin
  • beta-Transducin Repeat-Containing Proteins
  • Casein Kinase I
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Glycogen Synthase Kinase 3
  • Proteasome Endopeptidase Complex

Grants and funding

This work was supported by the 973 project of Ministry of Science and Technique of China (No. 2010CB529900), the National Natural Science Foundation of China (No. 81272318, No. 81272190), the Research Fund for the Doctoral Program of Higher Education of China (No. 20104306110005), the Science & Technology Department of Hunan Province (No. 13JJ6037, No. 2012RS4016), and the Scientific Research Fund of Hunan Provincial Education Department (No. 11A0 72, No. 13B068). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.