title: Relative contribution of four nucleases, CtIP, Dna2, Exo1 and Mre11, to the initial step of DNA double-strand break repair by homologous recombination in both the chicken DT40 and human TK6 cell lines.
abstract: Homologous recombination (HR) is initiated by double-strand break (DSB) resection, during which DSBs are processed by nucleases to generate 3' single-strand DNA. DSB resection is initiated by CtIP and Mre11 followed by long-range resection by Dna2 and Exo1 in Saccharomyces cerevisiae. To analyze the relative contribution of four nucleases, CtIP, Mre11, Dna2 and Exo1, to DSB resection, we disrupted genes encoding these nucleases in chicken DT40 cells. CtIP and Dna2 are required for DSB resection, whereas Exo1 is dispensable even in the absence of Dna2, which observation agrees with no developmental defect in Exo1-deficient mice. Despite the critical role of Mre11 in DSB resection in S. cerevisiae, loss of Mre11 only modestly impairs DSB resection in DT40 cells. To further test the role of CtIP and Mre11 in other species, we conditionally disrupted CtIP and MRE11 genes in the human TK6 B cell line. As with DT40 cells, CtIP contributes to DSB resection considerably more significantly than Mre11 in TK6 cells. Considering the critical role of Mre11 in HR, this study suggests that Mre11 is involved in a mechanism other than DSB resection. In summary, CtIP and Dna2 are sufficient for DSB resection to ensure efficient DSB repair by HR.
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Nguyen Ngoc
authors.initials: NN
authors.lastname: Hoa
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Remi
authors.initials: R
authors.lastname: Akagawa
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Yamasaki
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Hirota
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Sasa
authors.affiliation: Centre for Frontier Research, National Institute of Genetics, ROIS, Yata 1111, Mishima, Shizuoka, 411-8540, Japan.
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Natsume
authors.affiliation: Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Junya
authors.initials: J
authors.lastname: Kobayashi
authors.affiliation: Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan.
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Sakuma
authors.affiliation: Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Kenshi
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Centre for Frontier Research, National Institute of Genetics, ROIS, Yata 1111, Mishima, Shizuoka, 411-8540, Japan.|Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka, 411-8540, Japan.|JST, PREST, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Masato T
authors.initials: MT
authors.lastname: Kanemaki
authors.affiliation: Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
authors.forename: Yves
authors.initials: Y
authors.lastname: Pommier
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sasanuma
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002645:Chickens; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000378:metabolism; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D003851:Deoxyribonucleases / Q000235:genetics* / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000378:metabolism; D059765:Homologous Recombination; D006801:Humans
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D003851:Deoxyribonucleases; D005090:Exodeoxyribonucleases; D004265:DNA Helicases