title: The complexity of DNA double strand break is a crucial factor for activating ATR signaling pathway for G2/M checkpoint regulation regardless of ATM function.
abstract: DNA double strand break (DSB) repair pathway choice following ionizing radiation (IR) is currently an appealing research topic, which is still largely unclear. Our recent paper indicated that the complexity of DSBs is a critical factor that enhances DNA end resection. It has been well accepted that the RPA-coated single strand DNA produced by resection is a signaling structure for ATR activation. Therefore, taking advantage of high linear energy transfer (LET) radiation to effectively produce complex DSBs, we investigated how the complexity of DSB influences the function of ATR pathway on the G2/M checkpoint regulation. Human skin fibroblast cells with or without ATM were irradiated with X rays or heavy ion particles, and dual-parameter flow cytometry was used to quantitatively assess the mitotic entry at early period post radiation by detecting the cells positive for phosphor histone H3. In ATM-deficient cells, ATR pathway played a pivotal role and functioned in a dose- and LET-dependent way to regulate the early G2/M arrest even as low as 0.2Gy for heavy ion radiation, which indicated that ATR pathway could be rapidly activated and functioned in an ATM-independent, but DSB complexity-dependent manner following exposure to IR. Furthermore, ATR pathway also functioned more efficiently in ATM-proficient cells to block G2 to M transition at early period of particle radiation exposure. Accordingly, in contrast to ATM inhibitor, ATR inhibitor had a more effective radiosensitizing effect on survival fraction following heavy ion beams as compared with X ray radiation. Taken together, our results reveal that the complexity of DSBs is a crucial factor for the activation of ATR pathway for G2/M checkpoint regulation, and ATM-dependent end resection is not essential for the activation.
authors.affiliation: School of Public Health, Medical College of Soochow University, Suzhou, China; Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, School of Public Health, Soochow University, Suzhou, China.
authors.forename: Lian
authors.initials: L
authors.lastname: Xue
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Furusawa
authors.affiliation: International Open Laboratory, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okayasu
authors.affiliation: Oral Radiation Oncology, Department of Oral Restitution, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Miura
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Xing
authors.initials: X
authors.lastname: Cui
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Cuihua
authors.initials: C
authors.lastname: Liu
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Hirayama
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan. Electronic address: hyajima@nirs.go.jp.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Yajima
authors.affiliation: School of Radiological Medicine and Protection, Medical College of Soochow University, Suzhou, China. Electronic address: yudong@suda.edu.cn.
authors.forename: Dong
authors.initials: D
authors.lastname: Yu
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism* / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D016195:G2 Phase / Q000528:radiation effects; D059565:G2 Phase Cell Cycle Checkpoints / Q000235:genetics; D006801:Humans; D018499:Linear Energy Transfer; D010766:Phosphorylation; D011839:Radiation, Ionizing; D059767:Recombinational DNA Repair; D015398:Signal Transduction
chemical_list: D004247:DNA; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins
keywords: ATM; ATR; Complex DNA damage structure; DNA double strand breaks; DNA end resection; Early G2/M checkpoint