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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
Summary
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.
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