posted on 2022-05-26, 13:22authored byRachel Bayley, Valerie Borel, Rhiannon J Moss, Ellie Sweatman, Philip Ruis, Alice Ormrod, Amalia Goula, Rachel MA Mottram, Tyler Stanage, Graeme Hewitt, Marco Saponaro, Grant S Stewart, Simon J Boulton, Martin R Higgs
The 53BP1-RIF1-shieldin pathway maintains genome stability by suppressing nucleolytic degradation of DNA ends at double-strand breaks (DSBs). Although RIF1 interacts with damaged chromatin via phospho-53BP1 and facilitates recruitment of the shieldin complex to DSBs, it is unclear whether other regulatory cues contribute to this response. Here, we implicate methylation of histone H3 at lysine 4 by SETD1A-BOD1L in the recruitment of RIF1 to DSBs. Compromising SETD1A or BOD1L expression or deregulating H3K4 methylation allows uncontrolled resection of DNA ends, impairs end-joining of dysfunctional telomeres, and abrogates class switch recombination. Moreover, defects in RIF1 localization to DSBs are evident in patient cells bearing loss-of-function mutations in SETD1A. Loss of SETD1A-dependent RIF1 recruitment in BRCA1-deficient cells restores homologous recombination and leads to resistance to poly(ADP-ribose)polymerase inhibition, reinforcing the clinical relevance of these observations. Mechanistically, RIF1 binds directly to methylated H3K4, facilitating its recruitment to, or stabilization at, DSBs.
Funding
Crick (Grant ID: 10048, Grant title: Boulton FC001048)
European Research Council (Grant ID: 742437 - TelMetab, Grant title: ERC 742437 - TelMetab)