RNF168 binds and amplifies ubiquitin conjugates on damaged chromosomes to allow accumulation of repair proteins

Cell. 2009 Feb 6;136(3):435-46. doi: 10.1016/j.cell.2008.12.041.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Chromosomes / metabolism*
  • 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
  • Tumor Suppressor p53-Binding Protein 1
  • Ubiquitin / metabolism*
  • Ubiquitin-Protein Ligases / chemistry
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*

Substances

  • DNA-Binding Proteins
  • Histones
  • Intracellular Signaling Peptides and Proteins
  • RNF8 protein, human
  • TP53BP1 protein, human
  • Tumor Suppressor p53-Binding Protein 1
  • Ubiquitin
  • RNF168 protein, human
  • Ubiquitin-Protein Ligases