title: Cohesin promotes the repair of ionizing radiation-induced DNA double-strand breaks in replicated chromatin.
abstract: 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.
authors.affiliation: Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford OX3 7DQ, UK.
authors.forename: Christina
authors.initials: C
authors.lastname: Bauerschmidt
authors.forename: Cecilia
authors.initials: C
authors.lastname: Arrichiello
authors.forename: Susanne
authors.initials: S
authors.lastname: Burdak-Rothkamm
authors.forename: Michael
authors.initials: M
authors.lastname: Woodcock
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hill
authors.forename: David L
authors.initials: DL
authors.lastname: Stevens
authors.forename: Kai
authors.initials: K
authors.lastname: Rothkamm
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D002843:Chromatin / Q000528:radiation effects; D002868:Chromosomal Proteins, Non-Histone / Q000037:antagonists & inhibitors / Q000502:physiology*; D002869:Chromosome Aberrations; D053903:DNA Breaks, Double-Stranded; D053904:DNA Breaks, Single-Stranded; D004260:DNA Repair; D004261:DNA Replication; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors; D016195:G2 Phase; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors; D010750:Phosphoproteins / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D034622:RNA Interference; D011836:Radiation Tolerance; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors; D000097722:Cohesins; D000098550:Structural Maintenance of Chromosome Protein 1
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D025521:Tumor Suppressor Proteins; D000097722:Cohesins; D000098550:Structural Maintenance of Chromosome Protein 1; C429022:RAD21 protein, human; C576324:ATM protein, human