Basic Studies for JEM Space Experiments Using Human Neuron-like Cell Line, NB-1

Abstract

Our group of studies for JEM exploration experiment was selected and now is ready for operation. In space environment, 0.4 mSv/day of radiation exposure and microgravity condition will affect cellular metabolisms. In this study, a human neuron-like cell line, NB-1 was irradiated with 0.1 mGy or 1.0 mGy in single or 10 times fractionated treatment with 1 or 2 hour time-interval. Thirty minutes and 2 hours after the treatments, mRNA was isolated from the cells and DNA expression was studied with DNA microarray analysis. The results showed that change of the apoptosis related genes, such as apaf-1, cyt-c, caspase 3, 8, 9, p53, bax and MnSOD were shown. The genes of apaf-1, caspase 8, 9, p53 and MnSOD were upregulated, while those of cyt-c, caspase 3 and bax were downregulated. These results suggest that the low-dose irradiation induce intracellular oxidative stress, and may cause at least partial apoptosis-related gene expression changes.