@misc{oai:repo.qst.go.jp:00071383, author = {Katsube, Takanori and Mori, Masahiko and Tsuji, Hideo and Shiomi, Tadahiro and Bing, Wang and Nenoi, Mitsuru and Onoda, Makoto and 勝部 孝則 and 辻 秀雄 and 王 冰 and 根井 充 and 小野田 眞}, month = {Dec}, note = {Phosphorylated form of histone H2AX (γH2AX) is frequently used as a marker for DNA double-strand breaks (DSBs). It is, however, known that γH2AX foci do not necessarily correlate with DSBs in particular circumstances. We found a marked induction of γH2AX following oxidative stress induced by hydrogen peroxide (H2O2), although oxidative stress is thought to cause mostly base damages and single-strand breaks but hardly DSBs. γH2AX induced by H2O2 usually dispersed throughout the nucleus and did not necessarily represent distinct round shape foci. The immunoreactivity to γH2AX declined gradually with time but increased again at 24 h post-H2O2 treatment. While the removal of γH2AX foci induced by X-rays was hampered in non-homologous end joining (NHEJ)-deficient cells as compared to isogenic NHEJ-proficient cells, the kinetics of γH2AX foci formation and loss after H2O2 treatment were not affected by the potential of cells to repair DSBs. Analyses using specific inhibitors showed that ATR, rather than ATM, was a prominent kinase mediating the stress response to H2O2. These results suggest that induction of γH2AX by H2O2 does not necessarily depend on DSBs. γH2AX induction at early response to H2O2 was observed in both S- and non-S-phase cells. Some fraction of γH2AX within S-phase cells can be caused by stalled replication forks giving rise to long stretches of single-stranded DNA that activates ATR. Underlying mechanisms for γH2AX induction within non-S-phase cells were unclear. Reappearance of γH2AX at a later period might be correlated with cellular senescence, as this phenomenon was observed in the cells that were still being arrested without undergoing apoptosis, 第36回日本分子生物学会年会}, title = {Histone H2AX phosphorylation caused by oxidative stress is not dependent on DNA double-strand breaks and primarily mediated by ATR}, year = {2013} }