Abstract
In mammalian cells, it is speculated that low LET radiation induces transcriptional regulators via signal transductions by diverse kinds of radicals, and that the regulators contribute to decrease cellular damages. The analysis of molecular mechanisms of the cellular responses is useful to develop the methodology for regulation of the damages. Seveal radiation responsive genes have been identified in human fibroblast by HiCEP method. Their radiation responsiveness were examined in RAW267.7 mouse macrophage cells using quantitative real-time RT-PCR. We found that fra-2 mRNA was increased 2.3-fold after x-irradiation at 4Gy as similar to that in the human cells. It has been reported that Fra-2, a member of Fos family protein, is ubiquitously expressed during the embryogenesis and also required for the chondrogenesis. For further investigation, we constructed a reporter gene that possesses the upstream region of fra-2 gene. RAW264.7 cells with transient introduction of the reporter gene were irradiated and the expression levels of reporter gene were measeured. The enzymatic activity and transcript level were increased at 6-fold and 1.9-fold, respectively. We are now studying the nucleotide sequence essential for X-ray response of fra-2 gene and the results will be discussed.
