Pathways of DNA Double-Strand Break Repair during the Mammalian Cell Cycle
- 1 August 2003
- journal article
- research article
- Published by Taylor & Francis Ltd in Molecular and Cellular Biology
- Vol. 23 (16), 5706-5715
- https://doi.org/10.1128/mcb.23.16.5706-5715.2003
Abstract
Little is known about the quantitative contributions of nonhomologous end joining (NHEJ) and homologous recombination (HR) to DNA double-strand break (DSB) repair in different cell cycle phases after physiologically relevant doses of ionizing radiation. Using immunofluorescence detection of γ-H2AX nuclear foci as a novel approach for monitoring the repair of DSBs, we show here that NHEJ-defective hamster cells (CHO mutant V3 cells) have strongly reduced repair in all cell cycle phases after 1 Gy of irradiation. In contrast, HR-defective CHO irs1SF cells have a minor repair defect in G1, greater impairment in S, and a substantial defect in late S/G2. Furthermore, the radiosensitivity of irs1SF cells is slight in G1 but dramatically higher in late S/G2, while V3 cells show high sensitivity throughout the cell cycle. These findings show that NHEJ is important in all cell cycle phases, while HR is particularly important in late S/G2, where both pathways contribute to repair and radioresistance. In contrast to DSBs produced by ionizing radiation, DSBs produced by the replication inhibitor aphidicolin are repaired entirely by HR. irs1SF, but not V3, cells show hypersensitivity to aphidicolin treatment. These data provide the first evaluation of the cell cycle-specific contributions of NHEJ and HR to the repair of radiation-induced versus replication-associated DSBs.Keywords
This publication has 76 references indexed in Scilit:
- Efficient Rejoining of Radiation-induced DNA Double-strand Breaks in Centromeric DNA of Human CellsOnline Journal of Public Health Informatics, 2002
- Recombination at Double-Strand Breaks and DNA Ends: Conserved Mechanisms from Phage to HumansMolecular Cell, 2001
- Efficient rejoining of radiation-induced DNA double-strand breaks in vertebrate cells deficient in genes of the RAD52 epistasis groupOncogene, 2001
- DNA double-strand breaks associated with replication forks are predominantly repaired by homologous recombination involving an exchange mechanism in mammalian cellsJournal of Molecular Biology, 2001
- DNA double-strand break rejoining in xrs5 cells is more rapid in the G2 than in the G1 phase of the cell cycleMutation Research/DNA Repair, 1994
- Loss of S-phase-dependent radioresistance in irs-1 cells exposed to X-raysMutation Research/DNA Repair, 1994
- Radiation-sensitive irs mutants rejoin DNA double-strand breaks with efficiency similar to that of parental V79 cells but show altered response to radiation-induced G2 delayMutation Research/DNA Repair, 1992
- Cytogenetic characterization of the ionizing radiation-sensitive Chinese hamster mutant irs1Mutation Research/DNA Repair, 1991
- DNA-break repair, radioresistance of DNA synthesis, and camptothecin sensitivity in the radiation-sensitive irs mutants: Comparisons to ataxia-telangiectasia cellsMutation Research/DNA Repair, 1990
- Biochemical and genetic analysis of the Chinese hamster mutants irs1 and irs2 and their comparison to cultured ataxia telangiectasia cellsMutagenesis, 1990