@misc{oai:repo.qst.go.jp:00076612,
 author = {Konishi, Teruaki and Kobayashi, Alisa and Ohsawa, Daisuke and Autsavapormporn, Narongchai and Ahbrizal Farizal Tengku Ahmad, Tengku and Oikawa, Masakazu and Wang, Jun and Konishi, Teruaki and Kobayashi, Alisa and Ohsawa, Daisuke and Oikawa, Masakazu},
 month = {Aug},
 note = {Background: Direct exposure of the nucleus to radiation, is the primary cause of various radio-biological effects. However, the cytoplasm is equally exposed to radiation during treatments that result in activation of intra-cellular response. Underlying mechanisms of cytoplasmic damage response are not clearly understood.
Aim: The aim of this study is to clarify 1) whether cytoplasmic irradiation affect DSB repair, when the cytoplasm and nucleus is irradiated sequentially, and 2) whether the cytoplasmic irradiation alone is sufficient to induce DNA double strand breaks (DSB) in the nucleus. 
Material and Methods: To distinguish the radiobiological effects between nuclear and cytoplasmic irradiation, all the experiments were conducted using the SPICE-NIRS microbeam, that can target precisely the nucleus (N) and/or (C) with desired number of 3.4 MeV protons. We examined the kinetics of DSB repair in WI-38 normal human fibroblast cells that were precisely targeted to the N, C, or N+C. Cells were fixed at 1, 4, 8, 16, and 24 hours post-irradiation. In addition, we examined the activation of Keap1-Nrf2 oxidative stress response, and upregulation of DSB repair by XRCC4 and RAD51 expression after cytoplasmic irradiation by image analysis of immuno-fluorescently stained cells.
Results/Conclusion: Microbeam irradiation induced significant γ-H2AX, directly proportional to the number of protons delivered per N. In the C-targeted cells, γ-H2AX levels increase significantly at 4 hours post-irradiation, and not at 1 hr post-irradiation, and the increase was proportional to the delivered number of protons. Cells irradiated with 500 protons per N, showed lowered residual γ-H2AX levels in N+C cells additionally irradiated with 500 or 1000 protons targeted to the C, 16 hours and 24 hours post-irradiation, respectively. In addition, increase of RAD51 and XRCC4 expression and activation of NRF2 was observed by cytoplasmic irradiation. Our results suggest that cytoplasmic damage triggers enhanced defensive cellular response against nuclear irradiation., 16th International Congress of Radiation Research},
 title = {Activation of defensive cellular response triggered by microbeam induced cytoplasmic damage.},
 year = {2019}
}