Presentation Role of Endoplasmic Reticulum and Mitochondrion in proton microbeam irradiation induced bystander effect

Dong, Chen  ,  Konishi, Teruaki  ,  Tu, Wenzhi  ,  Kobayashi, Alisa  ,  Furusawa, Yoshiya  ,  Uchihori, Yukio  ,  K. Hei, Tom

With the progress of international aeronautics and space undertakings, the risk of cosmic rays exposed to spacecraft and astronauts became a hot topic in the world. The space environment beyond low earth orbit (LEO) contains several types of ionizing radiation, in which proton is the most abundant species and hence is an important irradiation source in space. It is well known that mitochondria and endoplasmic reticulum (ER) playing an important role in radiation-induced cellular response, the interaction of mitochondria and ER after cell nuclear or cytoplasmic stimuli is still largely unknown. In our previous study we found that mitochondria take a clearly part in radiation induced bystander effect (RIBE). In this paper we applied normal human fetal lung fibroblast cell (MRC-5) to compare the functions of mitochondria and ER in RIBE between cell nuclear and cytoplasmic irradiation with a counted proton particles. The results showed that both nuclear and cytoplasmic traversal lead to the increasing of micronucleus (MN) in bystander MRC-5 cells, which also had an association with the increased mitochondrial and ER mass. The drug rotenone and Bip-siRNA was used to suppress the function of mitochondria or ER for further confirming their function in RIBE. Mito-track assay showed different alteration in nuclear or cytoplasmic traversal after Bip-siRNA pretreated, while there’s no similar response in ER-track assay in which cells pretreated with rotenone. Interestingly, MN formation was increased in the bystander cells when same number of protons were delivered to more target positions rather than one site, and reactive oxygen species (ROS) were involved in the RIBE. Taken together, our studies provides an information useful for verifying the role of mitochondria and ER in non-targeted effects of ionizing radiation.
The 12th International Workshop on Microbeam Probes of Cellular Radiation Response

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