Investigations On Transcription Level Differences Of The DNA Damage-responsive Genes Rad9, Rad1 And Hus1 Among Various Mouse Tissues And Their Transcription Response To Gamma Ray Irradiation

Ionizing radiation could be found throughout the environment and is a potential hazard for human beings because it is both a mutagen and a carcinogen. So it is particularly important to study the biological effects of ionizing radiation and the mechanisms of damage repair that caused by ionizing radiation. These data will provide valuable information on the risk assessment and protection of ionizing radiation.Rad9, Rad1 and Hus1 are conserved from yeast to humans. They can form a heterotrimer complex (the 9-1-1 complex) that participates in the DNA damage repair, cell cycle checkpoint activation and apoptosis in eukaryotic cells. They play important roles in the maintenance of genome integrity and cellular responses to ionizing radiation.Purpose: It has been reported that in different human tissues, the expression levels of DNA damage repair genes are different. Furthermore, the expression level of DNA repair genes is different when DNA is damaged by radiation. But there is no report about the expression level of Rad9, Rad1 and Hus1 in normal tissues. Firstly, whether there was a correlation between three genes in transcriptional levels. Secondly, if the transcriptional level of each of them was same in different tissues. Thirdly, how they participate in the pathway of repair when suffering the ionizing radiation damage. Therefore, we systematically studied these questions using wild type mice as a model.Method: We mainly used real time quantitative PCR in our research. Firstly, we analyzed the transcriptional levels of Rad9, Rad1 and Hus1 in different normal mouse tissues of different sex. Secondly, the whole bodies of the mice were irradiated with 10 Gy gamma rays, and then their tissues were extracted at 2 h, 6 h, 12 h, 24 h and 48 h after irradiation. The sham-irradiated mice were used as controls. We then analyzed the changes of transcriptional level of Rad9, Rad1 and Hus1 in different tissues.Result: 1) The transcriptional levels of each of Rad9, Rad1 and Hus1 genes were different in various normal mouse tissues. But the transcriptional levels of Rad9, Rad1 and Hus1 genes showed a strong correlation, and the correlation relationship between Rad1 and Hus1 are strongest in all. Furthermore, there is no difference between the male mice and female mice. 2) After ionizing radiation, the transcriptional levels of Rad1 gene didn't have any change in the same tissue at different time points; the transcriptional levels of Rad9 and Hus1 were up-regulated in some time points, but they were not up-regulated in the same time point. The results show that the transcriptional levels among Rad9, Rad1 and Hus1 were not correlation in the same tissues after ionizing radiation. As a result, we supposed that there are some differences in the mechanisms of response to radiation among the three genes.