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The prolyl isomerase Pin1 affects Che-1 stability in response to apoptotic DNA damage

Francesca De Nicola1, Tiziana Bruno, Simona Iezzi

  • 1Laboratory B, Experimental Research Center and Rome Oncogenomic Center, Regina Elena Cancer Institute, Via delle Messi d'Oro 156, 00158 Rome, Italy.

The Journal of Biological Chemistry
|May 1, 2007
PubMed

Insights

DNA damage stabilizes Che-1, but apoptosis triggers its degradation via HMD2 and Pin1. This interaction regulates Che-1 levels, impacting cellular response to genotoxic stress and apoptosis.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Che-1 is an RNA polymerase II-binding protein crucial for transcriptional activation of p53 and the G(2)/M checkpoint.
  • Previous studies showed DNA damage stabilizes and accumulates Che-1.

Purpose of the Study:

  • To investigate the regulation of Che-1 during apoptosis.
  • To identify proteins interacting with Che-1 in response to apoptotic stimuli.

Main Methods:

  • Co-immunoprecipitation to assess protein interactions.
  • Ubiquitin-proteasome system assays to study protein degradation.
  • Analysis of Che-1 mutant lacking Pin1 binding capacity.
  • Genotoxic stress induction and apoptosis assays.

Main Results:

  • Che-1 is down-regulated during apoptosis.
  • The E3 ligase HMD2 interacts with Che-1 and targets it for degradation via the ubiquitin-proteasome system.
  • Che-1 interacts with Pin1 upon apoptotic stimuli, and Pin1 binding is required for Che-1/HMD2 interaction.
  • A Che-1 mutant unable to bind Pin1 shows increased half-life and reduced apoptosis following genotoxic stress.

Conclusions:

  • Che-1 is a novel target of Pin1 and HMD2.
  • Pin1 and HMD2-mediated degradation of Che-1 is a key mechanism regulating cellular response to DNA damage and apoptosis.
  • Che-1 plays a significant role in the cellular response to genotoxic stress.

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