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Updated: Aug 22, 2025

Strand-Specific Analysis of Proteins at Replicating DNA Strands by Enrichment and Sequencing of Protein-Associated Nascent DNA Method
08:53

Strand-Specific Analysis of Proteins at Replicating DNA Strands by Enrichment and Sequencing of Protein-Associated Nascent DNA Method

Published on: May 2, 2025

466

PARP1 proximity proteomics reveals interaction partners at stressed replication forks

Thorsten Mosler1, H Irem Baymaz1, Justus F Gräf1

  • 1Institute of Molecular Biology (IMB), Mainz 55128, Germany.

Nucleic Acids Research
|November 9, 2022
PubMed

Insights

TPX2 directly binds PARP1 (poly-ADP-ribose polymerase 1), regulating its activity during DNA replication stress. This interaction is crucial for cancer cells, particularly those with BRCA1/2 mutations, enhancing sensitivity to PARP inhibitors.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Genetics

Background:

  • PARP1 (poly-ADP-ribose polymerase 1) is crucial for DNA repair and targeted in BRCA1/2-deficient cancers.
  • The role of PARP1 regulation at stressed replication forks is not well understood.
  • BRCA1/2-deficient cells are vulnerable to PARP inhibitors due to loss of replication fork protection.

Purpose of the Study:

  • To identify regulators of PARP1 activity at stressed replication forks.
  • To investigate the role of TPX2 in DNA damage response and PARP1 regulation.

Main Methods:

  • Proximity proteomics of PARP1.
  • Isolation of proteins at stressed replication forks.
  • Analysis of TPX2 expression in cancer patient data.

Main Results:

  • TPX2 was identified as a direct PARP1-binding protein.
  • TPX2 regulates PARP1 auto-ADP-ribosylation activity.
  • TPX2 promotes homology-directed DNA repair and interacts with DNA damage response proteins.
  • Increased TPX2 mRNA levels correlate with BRCA1/2 mutations and PARP inhibitor sensitivity in cancers.

Conclusions:

  • TPX2 plays a mitosis-independent role in response to replication stress by interacting with PARP1.
  • TPX2 is a potential therapeutic target for enhancing PARP inhibitor efficacy in BRCA1/2-deficient cancers.

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