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.
- MeSH
- buněčné linie MeSH
- chromozomy * metabolismus MeSH
- DNA vazebné proteiny metabolismus MeSH
- dvouřetězcové zlomy DNA * MeSH
- genový knockdown MeSH
- histony metabolismus MeSH
- intracelulární signální peptidy a proteiny metabolismus MeSH
- lidé MeSH
- oprava DNA * MeSH
- terciární struktura proteinů MeSH
- ubikvitin * metabolismus MeSH
- ubikvitinligasy * chemie genetika metabolismus MeSH
- Check Tag
- lidé MeSH