The Human SRCAP Chromatin Remodeling Complex Promotes DNA-End Resection

Background: Repair of DNA double-strand breaks (DSBs) by homologous recombination requires 5'-3' resection of the DSB ends. In vertebrates, DSB resection is initiated by the collaborative action of CtIP and the MRE11-RAD50-NBS1 (MRN) complex. However, how this process occurs within the context of chromatin is still not well understood. Results: Here we identify the human SRCAP chromatin remodeling complex as a factor that promotes CtIP-dependent DNA-end resection. We show that SRCAP, which is mutated in Floating-Harbor syndrome, confers resistance to DNA damage-inducing agents and is recruited to DSBs. Moreover, we demonstrate that SRCAP is required for DNA-end resection, and thereby for recruitment of RPA and RAD51 to DSBs, and for the ensuing homologous recombination. Finally, we reveal that SRCAP forms a complex with CtIP and promotes accumulation of CUP at DSBs through a mechanism involving its ATPase activity. Conclusions: Our study implicates the human SRCAP chromatin remodeling complex as a novel regulator of DNA damage responses that orchestrates proper signaling and repair of DSBs in the context of chromatin.