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Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
10:24

Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins

Published on: September 28, 2012

MDM2 and Fbw7 cooperate to induce p63 protein degradation following DNA damage and cell differentiation

Francesco Galli1, Mariangela Rossi, Yuri D'Alessandra

  • 1Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.

Journal of Cell Science
|June 24, 2010
PubMed

Insights

MDM2 and Fbw7 cooperate to degrade DeltaNp63alpha protein. This pathway regulates levels of the pro-proliferative DeltaNp63alpha protein during DNA damage and cellular differentiation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • p63 protein levels require tight control during differentiation and apoptosis.
  • DeltaNp63alpha is a pro-proliferative protein whose levels must be regulated.

Purpose of the Study:

  • To elucidate a novel regulatory pathway for DeltaNp63alpha protein degradation.
  • To identify the roles of MDM2 and Fbw7 in controlling DeltaNp63alpha levels.

Main Methods:

  • Co-immunoprecipitation assays to detect protein interactions.
  • Western blotting to assess protein levels.
  • Site-directed mutagenesis to identify functional domains.
  • Depletion studies using siRNA/shRNA.

Main Results:

  • MDM2 binds DeltaNp63alpha in the nucleus, promoting its cytoplasmic translocation and subsequent degradation.
  • Fbw7 (FBXW7) E3-ubiquitin ligase targets cytoplasmic DeltaNp63alpha for degradation, requiring GSK3 kinase activity.
  • A specific phosphodegron in DeltaNp63alpha is essential for Fbw7-mediated degradation.
  • MDM2 or Fbw7 depletion prevents DeltaNp63alpha degradation following UV irradiation, adriamycin treatment, or keratinocyte differentiation.

Conclusions:

  • MDM2 and Fbw7 collaborate to regulate DeltaNp63alpha protein levels.
  • This regulatory mechanism is crucial for cellular responses to DNA damage and differentiation.

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