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A two-step mechanism governing PARP1-DNA retention by PARP inhibitors

Huijun Xue1, Amit Bhardwaj1, Yandong Yin1

  • 1Department of Biochemistry and Molecular Pharmacology and Perlmutter Cancer Center, New York University Grossman School of Medicine, New York, NY 10016, USA.

Science Advances
|September 7, 2022
PubMed

Insights

Poly (ADP-ribose) polymerase inhibitors (PARPi) target DNA repair. This study reveals PARPi

Area of Science:

  • Molecular Biology
  • Cancer Therapeutics
  • DNA Repair Mechanisms

Background:

  • Poly (ADP-ribose) polymerase inhibitors (PARPi) are promising cancer drugs.
  • PARPi target DNA repair pathways, but their precise mechanism on PARP1-DNA retention is unclear.

Purpose of the Study:

  • To elucidate the real-time mechanism of PARP1 retention on DNA lesions modulated by PARPi.
  • To understand how different PARPi affect PARP1 retention dynamics.

Main Methods:

  • Development of single-molecule assays for real-time monitoring of PARP1-DNA interactions.
  • Direct observation of PARP1 retention dynamics in the presence of PARPi.

Main Results:

  • A two-step mechanism for PARPi-mediated PARP1 retention was identified.
  • PARPi primarily inhibit catalysis by competing with NAD+ binding.
  • PARPi also induce allosteric modulation, affecting PARP1 retention differently (increase or release).
  • The potency of PARPi is mainly determined by their ability to outcompete NAD+.

Conclusions:

  • Findings provide a mechanistic understanding of PARPi action on PARP1-DNA retention.
  • This knowledge can guide the selection of PARPi based on their specific activities.
  • Enables the development of more effective and potent PARP inhibitors for cancer therapy.

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