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MDM2 binds and ubiquitinates PARP1 to enhance DNA replication fork progression

Celeste Giansanti1, Valentina Manzini1, Antje Dickmanns1

  • 1Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.

Cell Reports
|June 1, 2022
PubMed

Insights

High MDM2 levels accelerate DNA replication fork progression by inhibiting poly(ADP-ribose) polymerase 1 (PARP1). This mimics PARP1 inhibition and may represent a cancer cell vulnerability.

Area of Science:

  • Molecular Biology
  • Cancer Biology
  • Genetics

Background:

  • The MDM2 oncoprotein inhibits the tumor suppressor p53.
  • MDM2 also promotes DNA replication fork progression, independent of p53.
  • The role of MDM2 in DNA replication fork dynamics requires further elucidation.

Purpose of the Study:

  • To investigate the interaction between MDM2 and poly(ADP-ribose) polymerase 1 (PARP1).
  • To determine the effect of MDM2 on DNA replication fork progression and stability.
  • To explore the potential of targeting MDM2 as a cancer therapy.

Main Methods:

  • Co-immunoprecipitation assays to detect MDM2-PARP1 interaction.
  • Electron microscopy to visualize DNA replication fork structures.
  • Depletion studies using siRNA to assess the roles of RECQ1 and PRIMPOL.

Main Results:

  • MDM2 binds, inhibits, ubiquitinates, and destabilizes PARP1.
  • Increased MDM2 levels accelerate DNA replication fork progression, mimicking PARP1 inhibition.
  • MDM2 reduces fork reversal frequency and exacerbates camptothecin-induced cell death.

Conclusions:

  • High MDM2 levels phenocopy PARP1 inhibition in modulating fork restart.
  • MDM2's effect on DNA replication forks presents a potential vulnerability in cancer cells.
  • Targeting MDM2 may offer a novel therapeutic strategy for cancer treatment.
Keywords:
CP: Molecular biologyDNA replicationMDM2PARP1PRIMPOLRECQ1p53poly ADP ribosereplication fork reversalubiquitin

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