Molecular mechanisms of cellular responses to ionizing radiation and reactive oxygen species

细胞对电离辐射和活性氧反应的分子机制

基本信息

批准号：
15310037
负责人：
YONEI Shuji
金额：
$ 10.05万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15310037/
关键词：
Ionizing radiation Oxidative stress response DNA repair Base excision repair DNA glycosylase Regulation of gene expression Oxidative base damage Clustered DNA damage 放射線感受性活性酸素 APエンドヌクレアーゼ 8-オキソグアニンストレス応答過剰発現放射線塩基損傷二重

项目摘要

(1)It is well-known that ionizing radiation such as X-rays, gamma-rays and alpha-particles, produces a unique form of DNA damage called "clustered damage", which contains two or more lesions induced within the one or two helical turns of DNA. Many of the lesions induced by ionizing radiation are chemically indistinguishable from those induced by reactive oxygen species produced as by-products of oxidative metabolism. However, clustered damage induced by ionizing radiation would be less readily repaired than isolated lesions. Therefore clustered damage might be biologically significant. In this report we showed that HeLaS3 cells overexpressing hOGG1 in nucleus or mitochondria were more sensitive to gamma-rays than HeLaS3 cells. We have determined the level of chromosomal double strand breaks by gamma-H2AX foci formation, clustered damages produced by ionizing radiation might be converted to lethal double-strand breaks during attempted base excision repair. Our results that overexpressio … More n of hOGG1 in mitochondria protein enhanced the sensitivity to gamma-rays suggest that double-strand breaks are also induced by abortive base excision repair in mitochondrial genome. (2)Ionizing radiation and reactive oxygen species produce various types of oxidative damage to DNA, which cause mutations in cells. Bacteria and eukaryotes have DNA repair systems to prevent mutations. Oxidative base damages are principally repaired by base excision repair (BER) mechanisms. However, there are no indications that oxidative damages are directly reversed on the DNA strand. In this study, we examined whether oxidative damages are directly reversed on the DNA strand. We used pUB3 plasmid irradiated with gamma-rays and tsubsequently treated with a reducing agent, dithiolthreitol (DTT). E.coli cells were transformed with the pUB3. As a result, the transformation efficiency of pUB3 treated with DTT was higher than that of pUB3 without DTT treatment. We are currently investigating the mutation spectra of the pUB3. Less

(1)众所周知，X射线、伽马射线和α粒子等电离辐射会产生一种独特形式的DNA损伤，称为“簇状损伤”，其中包含在一个或两个损伤内诱发两个或多个损伤。许多由电离辐射引起的损伤在化学上与由氧化代谢副产物产生的活性氧引起的损伤是无法区分的。与孤立的损伤相比，聚集性损伤可能具有生物学意义，在本报告中，我们表明，在细胞核或线粒体中过度表达 hOGG1 的 HeLaS3 细胞比 HeLaS3 细胞对伽马射线更敏感。由于伽玛-H2AX焦点形成而断裂，电离辐射产生的聚集损伤可能在尝试碱基切除修复期间转化为致命的双链。线粒体蛋白中的hOGG1增强了对伽马射线的敏感性，这表明双链断裂也是由线粒体基因组中的碱基切除修复失败引起的。(2)电离辐射和活性氧对DNA产生各种类型的氧化损伤，从而引起突变。细菌和真核生物具有防止突变的 DNA 修复系统，主要通过碱基切除修复 (BER) 机制进行修复。在本研究中，我们检查了 DNA 链上的氧化损伤是否直接逆转，我们使用经过伽马射线照射并随后用还原剂二硫苏糖醇 (DTT) 处理的 pUB3 质粒。结果，经DTT处理的pUB3的转化效率高于未经DTT处理的pUB3。研究 pUB3 的突变谱。