@misc{oai:repo.qst.go.jp:00062652,
 author = {Sekine, Emiko and Yu, Dong and Ninomiya, Yasuharu and Fujimori, Akira and Anzai, Kazunori and Okayasu, Ryuichi and 関根 絵美子 and 于 冬 and 二宮 康晴 and 藤森 亮 and 安西 和紀 and 岡安 隆一},
 month = {Jul},
 note = {ATM (ataxia telangiectasia-mutated) protein responsible for a rare genetic disease with hyper-radiosensitivity, is the one of the earliest repair proteins sensing DNA double-strand breaks (DSB).  ATM is known to phosphorylate DNA repair proteins such as MRN complex (Mre11, Rad50 and NBS1), 53BP1, Artemis, Brca1, gamma-H2AX, and MDC. We studied the interactions between ATM and DNA-PKcs, a crucial NHEJ repair protein, after cells exposure to high and low LET irradiation. 
Normal human (HFL III, MRC5VA) and AT homozygote (AT2KY, AT5BIVA, AT3BIVA) cells were irradiated with X-rays and high LET radiation (carbon ions: 290MeV/n initial energy at 70 keV/um, and iron ions: 500MeV/n initial energy at 200KeV/um), and several critical end points were examined. AT cells with high LET irradiation showed a significantly higher radiosensitivity when compared with normal cells. The behavior of DNA DSB repair was monitored by immuno-fluorescence techniques using DNA-PKcs (pThr2609, pSer2056) and ATM (pSer1981) antibodies. In normal cells, the phosphorylation of DNA-PKcs was clearly detected after high LET irradiation, though the peak of phosphorylation was delayed when compared to X-irradiation. In contrast, almost no DNA-PKcs phosphorylation foci were detected in AT cells irradiated with high LET radiation. A similar result was also observed in normal cells treated with 10 uM ATM kinase specific inhibitor (KU55933) one hour before irradiation. These data suggest that the phosphorylation of DNA-PKcs with low LET X-rays is mostly ATM-independent, and the phosphorylation of DNA-PKcs with high LET radiation seems to require ATM probably due to its complex nature of DSB induced. Our study indicates that high LET heavy ion irradiation which we can observe in the space environment would provide a useful tool to study the fundamental mechanism associated with DNA DSB repair., 37th COSPAR Scientific Assembly},
 title = {ATM protein is indispensable to repair complex-type DNA double strand breaks induced by high LET heavy ion irradiation.},
 year = {2008}
}