BRCA2 prevents PARPi-mediated PARP1 retention to protect RAD51 filaments
成果类型：
Article
署名作者：
Lahiri, Sudipta; Hamilton, George; Moore, Gemma; Goehring, Liana; Huang, Tony T.; Jensen, Ryan B.; Rothenberg, Eli
署名单位：
New York University; Yale University
刊物名称：
Nature
ISSN/ISSBN：
0028-1803
DOI：
10.1038/s41586-025-08749-x
发表日期：
2025-04-24
关键词：
dna strand exchange
nucleoprotein filament
recombination
reca
gene
inhibition
interacts
DYNAMICS
olaparib
monomer
摘要：
The tumour-suppressor protein BRCA2 has a central role in homology-directed DNA repair by enhancing the formation of RAD51 filaments on resected single-stranded DNA generated at double-stranded DNA breaks and stimulating RAD51 activity1,2. Individuals with BRCA2 mutations are predisposed to cancer; however, BRCA2-deficient tumours are often responsive to targeted therapy with PARP inhibitors (PARPi)3, 4, 5-6. The mechanism by which BRCA2 deficiency renders cells sensitive to PARPi but with minimal toxicity in cells heterozygous for BRCA2 mutations remains unclear. Here we identify a previously unknown role of BRCA2 that is directly linked to the effect of PARP1 inhibition. Using biochemical and single-molecule approaches, we demonstrate that PARPi-mediated PARP1 retention on a resected DNA substrate interferes with RAD51 filament stability and impairs RAD51-mediated DNA strand exchange. Full-length BRCA2 protects RAD51 filaments and counteracts the instability conferred by PARPi-mediated retention by preventing the binding of PARP1 to DNA. Extending these findings to a cellular context, we use quantitative single-molecule localization microscopy to show that BRCA2 prevents PARPi-induced PARP1 retention at homologous-recombination repair sites. By contrast, BRCA2-deficient cells exhibit increased PARP1 retention at these lesions in response to PARPi. These results provide mechanistic insights into the role of BRCA2 in maintaining RAD51 stability and protecting homologous-recombination repair sites by mitigating PARPi-mediated PARP1 retention.