Abstract
Time changes (kinetics ) of gene in murine tissues expression after γ-ray irradiation with low-dose-rate (< 0.1 mGy/min) or middle-dose-rate (0.1 – 99mGy/min) remains to be elucidated. Based on the results of our previous microarray analyses using murine NIH3T3/PG13Luc cells, 5 genes, including Trp53-dependent genes (CyclinG1/Ccng1 and p21/Cdkn1a), extra-cellular matrix-related genes (Tnc, Col1a2 and Fbln5), were selected for markers to evaluate gene expressions in spleens of mice after irradiation. Female C3H mice were continuously irradiated for 1- 20 days at 400 mGy/22 hr/day. Time changes of the gene expression levels were analyzed by the real-time PCR method. The Trp53-dependent genes (Ccng1, Cdkn1a) were up-regulated earlier after the initiation of irradiation at the doses higher than 0.8 Gy. On the other hand, extra-cellular matrix related-genes (Col1a2, Tnc and Fbln5) were up-regulated later after the initiation of irradiation at the doses higher than 4.0 Gy. Such kinetics for cells of spleen cells from irradiated mice were quite similar to those in murine cell lines irradiated at middle-dose rates. On the other hands, any time changes of those gene expressions were not observed in 20 mGy/22hr/day. Because of the up- regulation pathways for Trp53-independent genes in murine tissues were different from those of extra-cellular matrix related genes after middle-dose- rate γ-ray irradiation, the regulation of these genes between Trp53-dependent and independent might be different. This study was supported by a grant from Aomori Prefecture, Japan.
