2. Academic Validation
  3. PRIMPOL-Mediated Adaptive Response Suppresses Replication Fork Reversal in BRCA-Deficient Cells

PRIMPOL-Mediated Adaptive Response Suppresses Replication Fork Reversal in BRCA-Deficient Cells

  • Mol Cell. 2020 Feb 6;77(3):461-474.e9. doi: 10.1016/j.molcel.2019.10.008.
Annabel Quinet 1,  Stephanie Tirman 2,  Jessica Jackson 1,  Saša Šviković 3,  Delphine Lemaçon 4,  Denisse Carvajal-Maldonado 4,  Daniel González-Acosta 5,  Alexandre T Vessoni 6,  Emily Cybulla 2,  Matthew Wood 2,  Steven Tavis 1,  Luis F Z Batista 6,  Juan Méndez 5,  Julian E Sale 3,  Alessandro Vindigni 7
Affiliations

Affiliations

  • 1 Division of Oncology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA.
  • 2 Division of Oncology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
  • 3 Division of Protein & Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
  • 4 Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
  • 5 Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain.
  • 6 Division of Hematology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
  • 7 Division of Oncology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA. Electronic address: [email protected].
PMID: 31676232 DOI: 10.1016/j.molcel.2019.10.008
Abstract

Acute treatment with replication-stalling chemotherapeutics causes reversal of replication forks. BRCA proteins protect reversed forks from nucleolytic degradation, and their loss leads to chemosensitivity. Here, we show that fork degradation is no longer detectable in BRCA1-deficient Cancer cells exposed to multiple cisplatin doses, mimicking a clinical treatment regimen. This effect depends on increased expression and chromatin loading of PRIMPOL and is regulated by ATR activity. Electron microscopy and single-molecule DNA fiber analyses reveal that PRIMPOL rescues fork degradation by reinitiating DNA synthesis past DNA lesions. PRIMPOL repriming leads to accumulation of ssDNA gaps while suppressing fork reversal. We propose that cells adapt to repeated cisplatin doses by activating PRIMPOL repriming under conditions that would otherwise promote pathological reversed fork degradation. This effect is generalizable to other conditions of impaired fork reversal (e.g., SMARCAL1 loss or PARP inhibition) and suggests a new strategy to modulate cisplatin chemosensitivity by targeting the PRIMPOL pathway.

Keywords

ATR; BRCA; DNA damage; DNA replication; PRIMPOL; adaptive response; replication fork repriming; replication fork reversal; replication stress response; ssDNA gaps.

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