biostudies-literatureSchmidt CKCancer Research UKEuropean Research CouncilWellcome Trust1458-1470https://www.ebi.ac.uk/biostudies/studies/S-EPMC4894550biostudies-literatureUnknown17(11)Ubiquitylation is crucial for proper cellular responses to DNA double-strand breaks (DSBs). If unrepaired, these highly cytotoxic lesions cause genome instability, tumorigenesis, neurodegeneration or premature ageing. Here, we conduct a comprehensive, multilayered screen to systematically profile all human ubiquitin E2 enzymes for impacts on cellular DSB responses. With a widely applicable approach, we use an exemplary E2 family, UBE2Ds, to identify ubiquitylation-cascade components downstream of E2s. Thus, we uncover the nuclear E3 ligase RNF138 as a key homologous recombination (HR)-promoting factor that functions with UBE2Ds in cells. Mechanistically, UBE2Ds and RNF138 accumulate at DNA-damage sites and act at early resection stages by promoting CtIP ubiquitylation and accrual. This worNature cell biologySystematic E2 screening reveals a UBE2D-RNF138-CtIP axis promoting DNA repair.PMC489455018796268536WT092096C6946/A14492092096A1122411224C6/A11224Demir MBeli PGalanty YCornwell MJackson SPSczaniecka-Clift MCoates JSchmidt CKJhujh SfalseSystematic E2 screening reveals a UBE2D-RNF138-CtIP axis promoting DNA repair.Ubiquitylation is crucial for proper cellular responses to DNA double-strand breaks (DSBs). If unrepaired, these highly cytotoxic lesions cause genome instability, tumorigenesis, neurodegeneration or premature ageing. Here, we conduct a comprehensive, multilayered screen to systematically profile all human ubiquitin E2 enzymes for impacts on cellular DSB responses. With a widely applicable approach, we use an exemplary E2 family, UBE2Ds, to identify ubiquitylation-cascade components downstream of E2s. Thus, we uncover the nuclear E3 ligase RNF138 as a key homologous recombination (HR)-promoting factor that functions with UBE2Ds in cells. Mechanistically, UBE2Ds and RNF138 accumulate at DNA-damage sites and act at early resection stages by promoting CtIP ubiquitylation and accrual. This wor2015-01-01T00:00:00Z2015 Nov2025-04-19T15:01:38.255Z2019-03-27T02:15:23ZS-EPMC48945502650205710.1038/ncb3260