Mitotic DNA synthesis is caused by transcription-replication conflicts in BRCA2-deficient cells

Aberrant replication causes cells lacking BRCA2 to enter mitosis with under-replicated DNA, which activates a repair mechanism known as mitotic DNA synthesis (MiDAS). Here, we identify genome-wide the sites where MiDAS reactions occur when BRCA2 is abrogated. High-resolution profiling revealed that...

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Bibliographic Details
Published in:Molecular cell Vol. 82; no. 18; p. 3382
Main Authors: Groelly, Florian J, Dagg, Rebecca A, Petropoulos, Michalis, Rossetti, Giacomo G, Prasad, Birbal, Panagopoulos, Andreas, Paulsen, Teressa, Karamichali, Angeliki, Jones, Samuel E, Ochs, Fena, Dionellis, Vasilis S, Puig Lombardi, Emilia, Miossec, Matthieu J, Lockstone, Helen, Legube, Gaëlle, Blackford, Andrew N, Altmeyer, Matthias, Halazonetis, Thanos D, Tarsounas, Madalena
Format: Journal Article
Language:English
Published: United States 15.09.2022
Subjects:
Aphidicolin - pharmacology
BRCA2 Protein - genetics
Chromosome Fragile Sites - genetics
DNA - genetics
DNA Damage
DNA Replication
Genomic Instability
Humans
Mitosis - genetics
genome stability
transcription-replication conflicts
MiDAS
TRCs
R-loops
mitotic DNA synthesis
BRCA2
ISSN:1097-4164, 1097-4164
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Summary:Aberrant replication causes cells lacking BRCA2 to enter mitosis with under-replicated DNA, which activates a repair mechanism known as mitotic DNA synthesis (MiDAS). Here, we identify genome-wide the sites where MiDAS reactions occur when BRCA2 is abrogated. High-resolution profiling revealed that these sites are different from MiDAS at aphidicolin-induced common fragile sites in that they map to genomic regions replicating in the early S-phase, which are close to early-firing replication origins, are highly transcribed, and display R-loop-forming potential. Both transcription inhibition in early S-phase and RNaseH1 overexpression reduced MiDAS in BRCA2-deficient cells, indicating that transcription-replication conflicts (TRCs) and R-loops are the source of MiDAS. Importantly, the MiDAS sites identified in BRCA2-deficient cells also represent hotspots for genomic rearrangements in BRCA2-mutated breast tumors. Thus, our work provides a mechanism for how tumor-predisposing BRCA2 inactivation links transcription-induced DNA damage with mitotic DNA repair to fuel the genomic instability characteristic of cancer cells.
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ISSN:1097-4164
1097-4164
DOI:10.1016/j.molcel.2022.07.011