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Transcriptional repressor NIR interacts with the p53-inhibiting ubiquitin ligase MDM2

Kristina Heyne1, Juliane Förster, Roland Schüle

  • 1José Carreras Research Center and Internal Medicine I, University of Saarland Medical Center, 66421 Homburg/Saar, Germany and Department of Urology, Center for Clinical Research, University of Freiburg, 79106 Freiburg, Germany.

Nucleic Acids Research
|January 14, 2014
PubMed

Insights

Novel INHAT repressor (NIR) binds p53 and MDM2, cooperating with MDM2 to suppress p53 transcriptional activity by inhibiting acetylation and stabilizing the p53:MDM2 complex.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Epigenetics

Background:

  • p53 is a tumor suppressor regulated by MDM2.
  • MDM2 inhibits p53 activity through ubiquitination and promoter binding.
  • Histone acetylation by p300/CBP is crucial for p53-mediated gene transactivation.

Purpose of the Study:

  • Investigate the interaction of NIR with p53 and MDM2.
  • Elucidate NIR's role in regulating p53 activity.
  • Determine the mechanism by which NIR influences the p53-MDM2 complex.

Main Methods:

  • Co-immunoprecipitation assays to detect protein-protein interactions.
  • Western blotting to assess protein levels and acetylation status.
  • Reporter assays to measure p53-mediated transactivation.

Main Results:

  • NIR binds directly to both p53 and MDM2.
  • NIR inhibits MDM2 ubiquitination and stabilizes MDM2.
  • NIR cooperates with MDM2 to repress p53 transactivation by blocking p53 and MDM2 acetylation.
  • NIR promotes the formation of a ternary complex involving p53, MDM2, and NIR.

Conclusions:

  • NIR acts as a co-repressor with MDM2 to suppress p53 transcriptional activity.
  • NIR's mechanism involves stabilizing the inhibitory p53:MDM2 complex through acetylation inhibition.
  • NIR represents a potential therapeutic target in cancers where p53 is functional.

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