Figure 4

ATP-dependent chromatin remodeling during mammalian double-strand break (DSB) repair. A variety of ATP-dependent chromatin-remodeling complexes slide, evict, and modify nucleosomes to assist DSB repair, by increasing accessibility to DNA and facilitating DNA end-resection. Recruitment of various NHEJ, HR and signaling factors, and induction and maintenance of histone modifications at the site of damage depend on the recruitment and activity of various remodeling complexes. ALC1, which regulates DSB repair, and the NuRD complex, which promotes DSB repair and aids checkpoint activation, are both recruited in a poly(ADP ribose) polymerase (PARP)-dependent manner, which may involve poly(ADP-ribos)ylation of histones. The TRRAP/Tip60 complex localizes to DSBs to acetylate histones, and promote subsequent repair and signaling events. The ACF and/or CHRAC complexes are recruited to sites of damage, and interact with KU70 to facilitate efficient NHEJ. The WICH complex phosphorylates histone H2AX in a non--canonical manner, and stimulates efficient damage signaling and recruitment of repair factors. Finally, SWI/SNF interacts with acetylated histones H3 and H4 at the site of damage and, together with INO80, facilitates phosphorylation of histone H2AX. Red dotted arrows depict chromatin recruitment and protein-protein interactions. See main text for more detail and references. *Sliding and eviction mechanisms are probably involved in both NHEJ and HR.