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Nuclear localization signals of the E-cadherin transcriptional repressor Snail

Hyeonseok Ko1, Hyun Sil Kim, Nam Hee Kim

  • 1Department of Biochemistry and Molecular Biology, Brain Korea 21 Project for Medical Science of Yonsei University, College of Medicine, Seoul, Korea.

Cells, Tissues, Organs
|June 26, 2007
PubMed

Insights

Nuclear localization signals are essential for Snail protein function. Inactivating these signals decreases Snail levels and repressor activity, highlighting their role in regulating Snail

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Developmental Biology

Background:

  • Snail is a key transcriptional repressor regulating epithelial-mesenchymal transition (EMT).
  • GSK3-beta mediated phosphorylation of Snail leads to its ubiquitination and degradation.
  • Wnt signaling inhibits Snail phosphorylation, increasing Snail protein levels.

Purpose of the Study:

  • To investigate the function of nuclear localization signals (NLS) within the Snail sequence.
  • To determine the role of NLS motifs in Snail's subcellular localization and transcriptional activity.
  • To understand how NLS motifs interact with phosphorylation-dependent degradation pathways.

Main Methods:

  • Site-directed mutagenesis to inactivate Snail NLS motifs.
  • Western blotting to assess total and nuclear Snail protein levels.
  • Reporter assays to measure Snail repressor activity on the E-cadherin promoter.
  • Treatment with GSK3 inhibitor (LiCl) to analyze Snail stability.

Main Results:

  • Mutational inactivation of NLS motifs decreased nuclear and total Snail protein levels.
  • NLS mutants exhibited attenuated Snail repressor activity on the E-cadherin promoter.
  • Cytoplasmic levels of NLS mutants increased in the presence of GSK3 inhibitor, indicating rapid degradation.

Conclusions:

  • Nuclear localization signals are critical for Snail's proper function and stability.
  • Snail's subcellular localization and expression are regulated by NLS motifs and GSK3-beta-dependent phosphorylation.
  • These findings reveal a conserved mechanism for Snail regulation across species.

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