Cohesin promotes the repair of ionizing radiation-induced DNA double-strand breaks in replicated chromatin

Nucleic Acids Res. 2010 Jan;38(2):477-87. doi: 10.1093/nar/gkp976. Epub 2009 Nov 11.


The cohesin protein complex holds sister chromatids together after synthesis until mitosis. It also contributes to post-replicative DNA repair in yeast and higher eukaryotes and accumulates at sites of laser-induced damage in human cells. Our goal was to determine whether the cohesin subunits SMC1 and Rad21 contribute to DNA double-strand break repair in X-irradiated human cells in the G2 phase of the cell cycle. RNA interference-mediated depletion of SMC1 sensitized HeLa cells to X-rays. Repair of radiation-induced DNA double-strand breaks, measured by gammaH2AX/53BP1 foci analysis, was slower in SMC1- or Rad21-depleted cells than in controls in G2 but not in G1. Inhibition of the DNA damage kinase DNA-PK, but not ATM, further inhibited foci loss in cohesin-depleted cells in G2. SMC1 depletion had no effect on DNA single-strand break repair in either G1 or late S/G2. Rad21 and SMC1 were recruited to sites of X-ray-induced DNA damage in G2-phase cells, but not in G1, and only when DNA damage was concentrated in subnuclear stripes, generated by partially shielded ultrasoft X-rays. Our results suggest that the cohesin complex contributes to cell survival by promoting the repair of radiation-induced DNA double-strand breaks in G2-phase cells in an ATM-dependent pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle Proteins / antagonists & inhibitors
  • Cell Cycle Proteins / physiology*
  • Chromatin / radiation effects
  • Chromosomal Proteins, Non-Histone / antagonists & inhibitors
  • Chromosomal Proteins, Non-Histone / physiology*
  • Chromosome Aberrations
  • DNA Breaks, Double-Stranded*
  • DNA Breaks, Single-Stranded
  • DNA Repair*
  • DNA Replication
  • DNA-Activated Protein Kinase / antagonists & inhibitors
  • DNA-Binding Proteins / antagonists & inhibitors
  • G2 Phase
  • HeLa Cells
  • Humans
  • Mitosis
  • Nuclear Proteins / antagonists & inhibitors
  • Phosphoproteins / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • RNA Interference
  • Radiation Tolerance
  • Tumor Suppressor Proteins / antagonists & inhibitors


  • Cell Cycle Proteins
  • Chromatin
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • RAD21 protein, human
  • Tumor Suppressor Proteins
  • cohesins
  • structural maintenance of chromosome protein 1
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • DNA-Activated Protein Kinase
  • Protein Serine-Threonine Kinases