RNF168 Binds and Amplifies Ubiquitin Conjugates on Damaged Chromosomes to Allow Accumulation of Repair Proteins

• Published in: Cell 2009-02, Vol.136 (3), p.435-446
• Main Authors: Doil, Carsten, Mailand, Niels, Bekker-Jensen, Simon, Menard, Patrice, Larsen, Dorthe Helena, Pepperkok, Rainer, Ellenberg, Jan, Panier, Stephanie, Durocher, Daniel, Bartek, Jiri, Lukas, Jiri, Lukas, Claudia
• Format: Article
• Language: English
• Subjects: Cell Line; Chromosomes - metabolism; DNA; DNA Breaks, Double-Stranded; DNA Repair; DNA-Binding Proteins - metabolism; Gene Knockdown Techniques; Histones - metabolism; Humans; Intracellular Signaling Peptides and Proteins - metabolism; Protein Structure, Tertiary; SIGNALING; Tumor Suppressor p53-Binding Protein 1; Ubiquitin - metabolism; Ubiquitin-Protein Ligases - chemistry; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/j.cell.2008.12.041

DNA double-strand breaks (DSBs) not only interrupt the genetic information, but also disrupt the chromatin structure, and both impairments require repair mechanisms to ensure genome integrity. We showed previously that RNF8-mediated chromatin ubiquitylation protects genome integrity by promoting the accumulation of repair factors at DSBs. Here, we provide evidence that, while RNF8 is necessary to trigger the DSB-associated ubiquitylations, it is not sufficient to sustain conjugated ubiquitin in this compartment. We identified RNF168 as a novel chromatin-associated ubiquitin ligase with an ability to bind ubiquitin. We show that RNF168 interacts with ubiquitylated H2A, assembles at DSBs in an RNF8-dependent manner, and, by targeting H2A and H2AX, amplifies local concentration of lysine 63-linked ubiquitin conjugates to the threshold required for retention of 53BP1 and BRCA1. Thus, RNF168 defines a new pathway involving sequential ubiquitylations on damaged chromosomes and uncovers a functional cooperation between E3 ligases in genome maintenance.