重离子所致DNA双链断裂损伤修复的γH2AX焦点响应  

Response of γH2AX Foci in Repair of DNA Double Strand Breaks Induced by Heavy Ions

作　　者：隋丽[1,2] 王豫[1] 关华[1] 孔福全[2] 周平坤[1] 

机构地区：[1]中国人民解放军军事医学科学院放射与辐射医学研究所,北京100850 [2]中国原子能科学研究院,北京102413

出　　处：《载人航天》2017年第2期245-251,共7页Manned Spaceflight

基　　金：载人航天预先研究项目(040101)

摘　　要：DNA双链断裂(DSB)是电离辐射所致基因组DNA的主要和最严重的损伤类型,磷酸化组蛋白γH2AX能比较特异地在DSB处形成焦点,是DSB的分子标志物之一。比较了重离子~7Li、^(12)C与γ射线辐照小鼠MEF细胞诱发γH2AX焦点的规律特征。结果显示,诱发形成的平均每个细胞的γH2AX焦点数目与照后时间相关,表达峰值出现在照后2 h,但不同类型辐射高表达的持续时间不同。在相同剂量下,致焦点形成率与辐射的LET值相关,LET值越高,形成率越大。γ射线诱发的γH2AX焦点尺寸随照后时间无明显变化,高LET重离子诱发的γH2AX焦点尺寸随时间变化先增加后减小;与低LET的γ射线相比,高LET辐射诱发的焦点平均尺寸明显变大,LET越高焦点尺寸越大且保持时间越长。DNA double-strand break （ DSB） is a major and severe damage of genomic DNA induced by ionizing radiation. In case of the occurrence of DSB, the histone protein H2AX is phosphorylated and recruited at DSB site to form phosphorylated H2AX （γH2AX） foci as a DSB biomarker. The yield, size and dynamics of γH2AX foci in mouse MEF cells induced by different linear energy transfer （ LET） radiation including heavy ions ^7 Li,^12 C and ^60 Coγ-ray were investigated. The results indicated that the average number ofγH2 AX foci per cell was changed as a function of time post-ir-radiation for all the radiations, and the peak of γH2AX foci formation appeared at 2h after irradia-tion. The persistence of increased number of foci was depended on the radiation type. The frequency of γH2AX foci production was associated with the LET value, the higher the LET, the greater the production frequency. The average size ofγ-H2AX foci induced byγ-rays was not changed with the post-irradiation times. An increase in the size of γH2AX foci induced by high LET ion beams was found, as compared with γ-rays irradiation. Moreover, the foci size increased with elevated LET.

关 键 词：基因组稳定性 DNA双链断裂 DNA修复 磷酸化组蛋白H2AX聚焦点 重离子 γ射线 

分 类 号：Q691.5[生物学—生物物理学] Q789