Give me a break, but not in mitosis: the mitotic DNA damage response marks DNA double-strand breaks with early signaling events

Cell Cycle. 2011 Apr 15;10(8):1215-21. doi: 10.4161/cc.10.8.15334. Epub 2011 Apr 15.


: DNA double-strand breaks (DSBs) are extremely cytotoxic with a single unrepaired DSB being sufficient to induce cell death. A complex signalling cascade, termed the DNA damage response (DDR), is in place to deal with such DNA lesions and maintain genome stability. Recent work by us and others has found that the signalling cascade activated by DSBs in mitosis is truncated, displaying apical, but not downstream, components of the DDR. The E3 Ubiquitin ligases RNF8, RNF168 and BRCA1, along with the DDR mediator 53BP1, are not recruited to DSB sites in mitosis, and activation of downstream checkpoint kinases is also impaired. Here, we show that RNF8 and RNF168 are recruited to DNA damage foci in late mitosis, presumably to prime sites for 53BP1 recruitment in early G1. Interestingly, we show that, although RNF8, RNF168 and 53BP1 are excluded from DSB sites during most of mitosis, they associate with mitotic structures such as the kinetochore, suggesting roles for these DDR factors during mitotic cell division. We discuss these and other recent findings and suggest how these novel data collectively contribute to our understanding of mitosis and how cells deal with DNA damage during this crucial cell cycle stage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • BRCA1 Protein / genetics
  • BRCA1 Protein / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Line, Tumor
  • DNA / genetics
  • DNA / metabolism
  • DNA Breaks, Double-Stranded
  • DNA Repair / physiology*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Female
  • Gene Expression Regulation
  • Genomic Instability
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Kinetochores / metabolism
  • Mitosis / genetics
  • Signal Transduction / genetics*
  • Tumor Suppressor p53-Binding Protein 1
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*
  • Ubiquitination


  • BRCA1 Protein
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • RNF8 protein, human
  • TP53BP1 protein, human
  • Tumor Suppressor p53-Binding Protein 1
  • DNA
  • RNF168 protein, human
  • Ubiquitin-Protein Ligases