Double-strand breaks (DSBs) are critical DNA lesions that robustly activate the elaborate DNA damage response (DDR) network. We identified a critical player in DDR fine-tuning: the E3/E4 ubiquitin ligase UBE4A. UBE4A's recruitment to sites of DNA damage is dependent on primary E3 ligases in the DDR and promotes enhancement and sustainment of K48- and K63-linked ubiquitin chains at these sites. This step is required for timely recruitment of the RAP80 and BRCA1 proteins and proper organization of RAP80- and BRCA1-associated protein complexes at DSB sites. This pathway is essential for optimal end resection at DSBs, and its abrogation leads to upregulation of the highly mutagenic alternative end-joining repair at the expense of error-free homologous recombination repair. Our data uncover a critical regulatory level in the DSB response and underscore the importance of fine-tuning the complex DDR network for accurate and balanced execution of DSB repair. The DNA damage response is activated by DNA double-strand breaks (DSBs) and involves protein ubiquitylation. Baranes-Bachar et al. show that, following initial ubiquitylation at DSB sites by E3 ubiquitin ligases, ubiquitin chains require further modulation by an E3/E4 ligase, UBE4A, to achieve optimal DSB repair.
Bibliographical noteFunding Information:
We thank Kay Hofmann for valuable help with designing the siRNA libraries for the high-throughput screen, Thanos Halazonetis for the anti-53BP1 antibody, Ron Hay for the anti-RNF4 antibody, Daniel Durocher for the FLAG-53BP1 construct, Niels Mailand for the K63-UIM construct and technical advice, Aaron Ciechanover and Rachel Klevit for useful advice, Björn Schumacher, Thorsten Hoppe, and Xingzhi Xu for stimulating discussions and exchange of information, and Ron Jachimowicz for critical reading of the manuscript. Work in the Y.S. laboratory is funded by research grants from the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation, the A-T Children's Project, the Israel Science Foundation Joint ISF-NSFC Research Program (jointly funded by the Israel Science Foundation and the National Natural Science Foundation of China - Grant No. 998/14), and the Israel Cancer Research Fund (Professorship). T.M. and T.C.V. were supported by funding from the Intramural Research Program of the National Institutes of Health (NIH), National Cancer Institute, and the Center for Cancer Research. Work in the K.R. laboratory is supported by the Swiss National Science Foundation (31003A_141197) and the Medical Research Council, UK (MC_PC_12001/1). Work in the G.D. laboratory is supported by a discovery grant from the Natural Sciences and Engineering Research Council of Canada (RGPIN 05616). Work in the P.H. lab was supported by an R+D+I grant from the Spanish Ministry of Economy and Competitivity (SAF2013-43255-P) and an ERC starting grant (DSBRECA). Work in the E.R. laboratory is supported by NIH grants GM108119 and CA187612 and American Cancer Society grant ACS130304-RSG-16-241-01-DMC. I.S.-B. is the recipient of a Ph.D. fellowship from the University of Sevilla. D.C. was supported by a Nova Scotia graduate scholarship. K.B.B. is a Jack and Florence Berlin fellow. Y.S. is a Research Professor of the Israel Cancer Research Fund.
© 2018 Elsevier Inc.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology