Journal
JOURNAL OF CELL SCIENCE
Volume 125, Issue 15, Pages 3529-3534Publisher
COMPANY OF BIOLOGISTS LTD
DOI: 10.1242/jcs.105353
Keywords
DNA double-strand breaks; BRCA1; 53BP1; gamma H2AX; DNA damage; IRIF; Structured Illumination; Super-resolution microscopy
Categories
Funding
- Sir Henry Wellcome Postdoctoral Fellowship
- Cancer Research UK
- ERC
- European Advanced Investigator Grant (DDREAM)
- European Community [HEALTH-F2-2012-259893]
- Wellcome Trust
- University of Cambridge
- Cancer Research UK [11224, 11581] Funding Source: researchfish
Ask authors/readers for more resources
Following irradiation, numerous DNA-damage-responsive proteins rapidly redistribute into microscopically visible subnuclear aggregates, termed ionising-radiation-induced foci (IRIF). How the enrichment of proteins on damaged chromatin actually relates to DNA repair remains unclear. Here, we use super-resolution microscopy to examine the spatial distribution of BRCA1 and 53BP1 proteins within single IRIF at subdiffraction-limit resolution, yielding an unprecedented increase in detail that was not previously apparent by conventional microscopy. Consistent with a role for 53BP1 in promoting DNA double-strand break repair by non-homologous end joining, 53BP1 enrichment in IRIF is most prominent in the G0/G1 cell cycle phases, where it is enriched in dense globular structures. By contrast, as cells transition through S phase, the recruitment of BRCA1 into the core of IRIF is associated with an exclusion of 53BP1 to the focal periphery, leading to an overall reduction of 53BP1 occupancy at DNA damage sites. Our data suggest that the BRCA1-associated IRIF core corresponds to chromatin regions associated with repair by homologous recombination, and the enrichment of BRCA1 in IRIF represents a temporal switch in the DNA repair program. We propose that BRCA1 antagonises 53BP1-dependent DNA repair in S phase by inhibiting its interaction with chromatin proximal to damage sites. Furthermore, the genomic instability exhibited by BRCA1-deficient cells might result from a failure to efficiently exclude 53BP1 from such regions during S phase.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available