報告書番号

G03002

タイトル（和文）

低線量率放射線が遺伝子発現量の変動に与える影響 -cDNAマイクロアレイとリアルタイムRT-PCRによる解析-

タイトル（英文）

Analysis of effecs of low-dose-rate ionizing radiation on gene expression using cDNA microarray and realtime RT-PCR

概要 （図表や脚注は「報告書全文」に掲載しております）

低線量率放射線対する生物応答の機構解明の一環として、cDNAマイクロアレイおよびリアルタイムPCRといった最先端の手法を用いて遺伝子発現の挙動を検討した。cDNAマイクロアレイは、同時に多数の遺伝子について情報を得ることができる非常に強力な方法であったが、低線量率放射線の影響は検出できず、低線量率では変動が微妙であるためより高感度の手法が必要であると考えられた。リアルタイムRT-PCRは、少数の遺伝子に限定して高感度に解析を行ことができ、この方法を用いることにより低線量率放射線により発現誘導が見られる遺伝子を検出することができた。今回変動が見られた遺伝子は、放射線応答で重要な位置を占める遺伝子の一つであり、そのような遺伝子において変動を検出できたことは、細胞内情報伝達経路における上流や下流の探索を通じて、低線量率放射線に対する分子レベルの応答機構を解明する上での糸口を得たものと考えられる。

概要 （英文）

In these days many researchers are concerning on the difference of effects between high and low dose rate ionizing radiation. But molecular mechanism of response to low dose rate irradiation is still unknown.Recently, some powerful methods to investigate gene expression developed. cDNA microarray is a powerful method to be able to detect expression of hundreds or thousands of genes at once, and realtime RT-PCR is a sensitive method to analyze limited numbers of genes precisely. These two methods are complementary, and are used together in general. So we analyzed the effects of low dose rate radiation on gene expression with both methods. At first, we showed to be able to detect the difference of gene expression between two cell lines, rat liver epithelial cells WB-F344 and its mutant cell line WB-aB1. Next, we analyzed effects of high dose irradiation with yeast cDNA microarray and we confirmed to be able to detect the changes of expression of radiation responding genes reported. Then we analyzed low dose rate effect with mouse fibroblast cells, but we didn’t detect any significant change of gene expression. The change of gene expression by low dose rate irradiation might be too modest to detect under the limitation of the method of cDNA microarray.Then, we analyzed low dose rate effect using realtime RT-PCR. We analyzed the effect on cell cycle regulating gene p21waf1 which is reported to response to high dose rate irradiation. After more than 1 day irradiation with 1 mGy/hr, the expression of p21 was increased and the increase was observed at least 13 days irradiation.From these result, cDNA microarray is global but less sensitive method, and it isn’t suitable to the purpose to pick up expression modified genes by modest stimulation as low dose rate irradiation. On the other hand, realtime RT-PCR is not global but sensitive method, and we could detect low dose rate responsive gene. It would be expected to be a clue of the mechanism of response to low dose rate ionizing irradiation.

報告者

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