| Autor: |
Nishi R; The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, United Kingdom. rnishi@fc.ritsumei.ac.jp.; Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Shiga, 525-8577, Japan. rnishi@fc.ritsumei.ac.jp., Wijnhoven PWG; The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, United Kingdom.; Bioscience Oncology, IMED Biotech Unit, AstraZeneca, Cambridge, United Kingdom., Kimura Y; Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Shiga, 525-8577, Japan., Matsui M; Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Shiga, 525-8577, Japan., Konietzny R; Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, United Kingdom., Wu Q; Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom., Nakamura K; Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Shiga, 525-8577, Japan., Blundell TL; Department of Biochemistry, University of Cambridge, Sanger Building, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom., Kessler BM; Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, United Kingdom. |
| Abstrakt: |
Non-homologous end-joining (NHEJ), which can promote genomic instability when dysfunctional, is a major DNA double-strand break (DSB) repair pathway. Although ubiquitylation of the core NHEJ factor, Ku (Ku70-Ku80), which senses broken DNA ends, is important for its removal from sites of damage upon completion of NHEJ, the mechanism regulating Ku ubiquitylation remains elusive. We provide evidence showing that the ubiquitin carboxyl-terminal hydrolase L3 (UCHL3) interacts with and directly deubiquitylates one of the Ku heterodimer subunits, Ku80. Additionally, depleting UCHL3 resulted in reduced Ku80 foci formation, Ku80 binding to chromatin after DSB induction, moderately sensitized cells to ionizing radiation and decreased NHEJ efficiencies. Mechanistically, we show that DNA damage induces UCHL3 phosphorylation, which is dependent on ATM, downstream NHEJ factors and UCHL3 catalytic activity. Furthermore, this phosphorylation destabilizes UCHL3, despite having no effect on its catalytic activity. Collectively, these data suggest that UCHL3 facilitates cellular viability after DSB induction by antagonizing Ku80 ubiquitylation to enhance Ku80 retention at sites of damage. |
