Sensor and effector kinases in DNA damage checkpoint regulate capacity for homologous recombination repair of fission yeast in G2 phase

• Published in: DNA repair Vol. 11; no. 8; pp. 666 - 675
• Main Authors: Yasuhira, Shinji, Saito, Takeshi, Maesawa, Chihaya, Masuda, Tomoyuki
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.2012; Elsevier
• Subjects: ATR kinase; Bacteriology; Biological and medical sciences; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell cycle, cell proliferation; Cell physiology; Checkpoint Kinase 1; Checkpoint Kinase 2; Chk1/2 kinases; DNA Breaks, Double-Stranded - radiation effects; DNA Damage - physiology; DNA damage checkpoint; DNA Helicases - metabolism; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; G2 arrest; G2 Phase Cell Cycle Checkpoints - physiology; Gamma Rays - adverse effects; Gene Deletion; Growth, nutrition, cell differenciation; Homologous recombination; Microbiology; Molecular and cellular biology; Molecular genetics; Mutagenesis. Repair; Protein Kinases - genetics; Protein Kinases - metabolism; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Recombinational DNA Repair - physiology; Schizosaccharomyces - physiology; Schizosaccharomyces - radiation effects; Schizosaccharomyces pombe Proteins - genetics; Schizosaccharomyces pombe Proteins - metabolism; DNA damage checkpoint; Chk1/2 kinases; G2 arrest; Homologous recombination; ATR kinase; Ascomycota; Enzyme; Transferases; Fungi; Regulation(control); Kinase; DNA; Cell cycle; G2 Phase; Schizosaccharomyces pombe; Lesion; Repair; Control point
• ISSN: 1568-7864; 1568-7856
• DOI: 10.1016/j.dnarep.2012.05.006

► Effect of checkpoint-deficiency on DSB repair was studied under forced G2 arrest. ► Repair defect was manifest only after high dose irradiation. ► DSB-induced foci formation by the repair proteins was not affected. ► Disappearance of the foci was markedly delayed. ► The checkpoint has a role downstream of, or in parallel to the core repair reaction. Although the G2/M DNA damage checkpoint is currently viewed as a set of coordinated cellular responses affecting both cell cycle progression and non-cell cycle targets, the relative contributions of the two target categories to DNA repair and cell survival after exposure to ionizing radiation have not been clearly addressed. We investigated how rad3 (ATR ortholog) or chk1/cds1 (CHK1/CHK2 orthologs) null mutations change the kinetics of double-strand break (DSB) repair in Schizosaccharomyces pombe cells under conditions of forced G2 arrest. After 200-Gy γ-ray irradiation, DSBs were repaired in rad3Δ cdc25-22 or chk1Δ cds1Δ cdc25-22 cells, almost as efficiently as in cdc25-22 cells at the restrictive temperature. In contrast, little repair was observed in the checkpoint-deficient cells up to 4h after higher-dose (500Gy) irradiation, whereas repair was still efficient in the control cdc25-22 cells. Immediate loss of viability appeared not be responsible for the repair defect after the higher dose, since both checkpoint-proficient and deficient cells with cdc25-22 allele synchronously resumed cycling with a similar time course when released to the permissive temperature 4h after irradiation. Recruitment of repair proteins Rad11 (Rpa1 ortholog), Rad22 (Rad52 ortholog), and Rhp54 (Rad54 ortholog) to the damage sites was not significantly impaired in the checkpoint-deficient cells, whereas their release was profoundly delayed. Our results suggest that sensor and effector kinases in the damage checkpoint machinery affect the efficiency of repair downstream of, or in parallel with the core repair reaction.