A role for RNA and DNA:RNA hybrids in the modulation of DNA repair by homologous recombination

DNA double-strand breaks (DSBs) are toxic DNA lesions which, if not properly repaired, may lead to genomic instability, cell death and senescence. Damage-induced long non-coding RNAs (dilncRNAs) are transcribed from broken DNA ends and contribute to DNA damage response (DDR) signaling. Here we show that dilncRNAs play a role in DSB repair by homologous recombination (HR) by contributing to the recruitment of the HR proteins BRCA1, BRCA2, and RAD51, without affecting DNA-end resection. In S/G2-phase cells, dilncRNAs pair to the resected DNA ends and form DNA:RNA hybrids, which are recognized by BRCA1 and promote its recruitment to DSBs. We also show that RNase H2 is in a complex with the HR proteins BRCA1, PALB2, BRCA2, and RAD51, and that it localizes to DSBs in the S/G2 cell-cycle phase. BRCA2 controls DNA:RNA hybrid levels at DSBs by mediating RNase H2 recruitment and, therefore, hybrids degradation. These results demonstrate that regulated DNA:RNA hybrid levels at DSBs contribute to HR-mediated repair.