@misc{oai:repo.qst.go.jp:00068763,
 author = {Okayasu, Ryuichi and Okabe, Atsushi and Takakura, Kaoru and 岡安 隆一 and 岡部 篤史 and 高倉 かほる},
 month = {Nov},
 note = {Normal human and ataxia telangiectasia (AT) homozygote fibroblasts were irradiated with 2 Gy X-rays, 70 keV/um carbon (290MeV/n) and 200 keV/um iron ions (500MeV/n) at plateau phase cultures, and the kinetics of phosphorylation in various proteins associated with DNA double strand break (DSB) repair were compared. In normal cells, peaks of GammaH2AX foci formation were observed 30 to 60 min post-irradiation for three kinds of radiations, and the disappearance of gamma-H2AX foci was much faster for X-irradiated samples than that for samples irradiated with heavy ions. In AT cells, on the other hand, the peaks of gamma-H2AX phosphorylation for carbon and iron samples were delayed for one to two hours when compared to that for X-rays. The phosphorylation of DNA-PKcs (at threonine 2609) in normal cells was significantly delayed in carbon and iron irradiated cells when compared to X-irradiated cells. Disappearance of DNA-PKcs sites in normal cells was much faster in X-irradiated samples than carbon and iron samples as in the case of gamma-H2AX. However, we were not able to detect DNA-PKcs phosphorylation signals in AT cells irradiated with high LET heavy ions, although DNA-PKcs foci were observed with AT cells irradiated with X-rays. Moreover, in the case of ATM protein phosphorylation (serine 1981) in normal cells, iron irradiation alone caused a significant initial delay, but the kinetics of disappearance is similar for iron and carbon samples with much higher number of remaining foci in iron samples than those for X-rays and carbon ions. 
\nThese results indicate that 1) high LET irradiation induces complex and/or severe DNA DSB damage which affects the functions of crucial DSB repair proteins, 2) Both ATM and DNA-PKcs may recognize the complexity of DSBs, and 3) ATM may be critical in repairing the complex form of DSB damage such as the one induced by high LET radiation., Radiation Research Society 53rd Annual Meeting},
 title = {ATM protein plays a critical role in repairing the complex DNA double strand breaks induced by hogh LET radiation},
 year = {2006}
}