POLθ processes ssDNA gaps and promotes replication fork progression in BRCA1-deficient cells
- Author(s)
- Anna Schrempf, Sara Bernardo, Emili A Arasa Verge, Miguel A Ramirez Otero, Jordan Wilson, Dominik Kirchhofer, Gerald Timelthaler, Anna M Ambros, Atilla Kaya, Marcus Wieder, Gerhard F Ecker, Georg E Winter, Vincenzo Costanzo, Joanna I Loizou
- Abstract
Polymerase theta (POLθ) is an error-prone DNA polymerase whose loss is synthetically lethal in cancer cells bearing breast cancer susceptibility proteins 1 and 2 (BRCA1/2) mutations. To investigate the basis of this genetic interaction, we utilized a small-molecule inhibitor targeting the POLθ polymerase domain. We found that POLθ processes single-stranded DNA (ssDNA) gaps that emerge in the absence of BRCA1, thus promoting unperturbed replication fork progression and survival of BRCA1 mutant cells. A genome-scale CRISPR-Cas9 knockout screen uncovered suppressors of the functional interaction between POLθ and BRCA1, including NBN, a component of the MRN complex, and cell-cycle regulators such as CDK6. While the MRN complex nucleolytically processes ssDNA gaps, CDK6 promotes cell-cycle progression, thereby exacerbating replication stress, a feature of BRCA1-deficient cells that lack POLθ activity. Thus, ssDNA gap formation, modulated by cell-cycle regulators and MRN complex activity, underlies the synthetic lethality between POLθ and BRCA1, an important insight for clinical trials with POLθ inhibitors.
- Organisation(s)
- Department of Pharmaceutical Sciences
- External organisation(s)
- Medizinische Universität Wien, IFOM-FIRC Institute of Molecular Oncology, Österreichische Akademie der Wissenschaften (ÖAW), Universität Wien
- Journal
- Cell Reports
- Volume
- 41
- ISSN
- 2211-1247
- DOI
- https://doi.org/10.1016/j.celrep.2022.111716
- Publication date
- 11-2022
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 301207 Pharmaceutical chemistry, 301301 Human genetics
- Keywords
- ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Sustainable Development Goals
- SDG 3 - Good Health and Well-being
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/pol-processes-ssdna-gaps-and-promotes-replication-fork-progression-in-brca1deficient-cells(125bc53e-8b29-45a1-9a80-ef4b859d9914).html