Small C-terminal domain phosphatase enhances snail activity through dephosphorylation

J Biol Chem. 2009 Jan 2;284(1):640-648. doi: 10.1074/jbc.M806916200. Epub 2008 Nov 12.

Abstract

Down-regulation of E-cadherin plays an important role in epithelial-mesenchymal transition (EMT), which is critical in normal development and disease states such as tissue fibrosis and metastasis. Snail, a key transcription repressor of E-cadherin, is a labile protein with a short half-life and is regulated through phosphorylation, ubiquitination, and degradation. Previously, we showed that GSK-3beta phosphorylated two stretches of serine residues within the nuclear export signal and the destruction box of Snail, provoking its cytoplasmic export for ubiquitin-mediated proteasome degradation. However, the mechanism of Snail dephosphorylation and the identity of the Snail-specific phosphatase remain elusive. Using a functional genomic screening, we found that the small C-terminal domain phosphatase (SCP) is a specific phosphatase for Snail. SCP interacted and co-localized with Snail in the nucleus. We also found that SCP expression induced Snail dephosphorylation and stabilization in vitro and in vivo. However, a catalytically inactive mutant of SCP had no effect on Snail. Furthermore, we found that Snail stabilization induced by SCP enhanced snail activity in the suppression of E-cadherin and increased cell migration. Thus, our findings indicate that SCP functions as a Snail phosphatase to control its phosphorylation and stabilization, and our study provides novel insights for the regulation of Snail during EMT and cancer metastasis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / physiology
  • Cadherins / biosynthesis*
  • Cadherins / genetics
  • Cell Movement / physiology*
  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism*
  • Glycogen Synthase Kinase 3 / genetics
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • HeLa Cells
  • Humans
  • Neoplasm Metastasis
  • Neoplasms / genetics
  • Neoplasms / metabolism
  • Nuclear Export Signals / physiology
  • Phosphoprotein Phosphatases / genetics
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation / physiology
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / metabolism
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Snail Family Transcription Factors
  • Substrate Specificity / physiology
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Ubiquitin / genetics
  • Ubiquitin / metabolism

Substances

  • Cadherins
  • Nuclear Export Signals
  • Repressor Proteins
  • Snail Family Transcription Factors
  • Transcription Factors
  • Ubiquitin
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Glycogen Synthase Kinase 3
  • Phosphoprotein Phosphatases
  • Proteasome Endopeptidase Complex