BRCA2 BRC missense variants disrupt RAD51-dependent DNA repair
- Yale University, United States
- New York University, United States
Abstract
Pathogenic mutations in the BRCA2 tumor suppressor gene predispose to breast, ovarian, pancreatic, prostate, and other cancers. BRCA2 maintains genome stability through homology-directed repair (HDR) of DNA double-strand breaks (DSBs) and replication fork protection. Nonsense or frameshift mutations leading to truncation of the BRCA2 protein are typically considered pathogenic, however, missense mutations resulting in single amino acid substitutions can be challenging to functionally interpret. The majority of missense mutations in BRCA2 have been classified as Variants of Uncertain Significance (VUS) with unknown functional consequences. In this study, we identified three BRCA2 VUS located within the BRC repeat region to determine their impact on canonical HDR and fork protection functions. We provide evidence that S1221P and T1980I, which map to conserved residues in the BRC2 and BRC7 repeats, compromise the cellular response to chemotherapeutics and ionizing radiation, and display deficits in fork protection. We further demonstrate biochemically that S1221P and T1980I disrupt RAD51 binding and diminish the ability of BRCA2 to stabilize RAD51-ssDNA complexes. The third variant, T1346I, located within the spacer region between BRC2 and BRC3 repeats, is fully functional. We conclude that T1346I is a benign allele whereas S1221P and T1980I are hypomorphic disrupting the ability of BRCA2 to fully engage and stabilize RAD51 nucleoprotein filaments. Our results underscore the importance of correctly classifying BRCA2 VUS as pathogenic variants can impact both future cancer risk and guide therapy selection during cancer treatment.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files.
Article and author information
Author details
Judit Jimenez-Sainz
Funding
National Cancer Institute (CA215990)
- Ryan B Jensen
Chavkin Philanthropic
- Eli Rothenberg
Women's Health Research at Yale
- Ryan B Jensen
The Gray Foundation
- Ryan B Jensen
Lion Heart Pilot Grant
- Judit Jimenez-Sainz
National Institutes of Health (R35 GM134947)
- Eli Rothenberg
National Institutes of Health (AI153040)
- Eli Rothenberg
National Institutes of Health (CA247773)
- Eli Rothenberg
The V Foundation BRCA Research
- Eli Rothenberg
Pfizer
- Eli Rothenberg
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Jimenez-Sainz et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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BRCA2 BRC missense variants disrupt RAD51-dependent DNA repair
eLife 11:e79183.
https://doi.org/10.7554/eLife.79183
