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，电离辐射（例如X射线，伽马射线和α粒子）产生一种独特的DNA损伤形式，称为“聚集损伤”，其中包含在一个或两个螺旋的DNA中诱导的两个或多个病变。电离辐射引起的许多病变在化学上与由氧化代谢副产品产生的活性氧诱导的病变无法区分。然而，与孤立病变相比，电离辐射引起的聚类损伤将不易修复。因此，聚集损伤可能具有生物学意义。在本报告中，我们表明，在核或线粒体中过表达HOGG1的HELAS3细胞比HELAS3细胞更敏感。我们已经确定了通过γ-H2AX焦点形成染色体双链断裂的水平，在尝试的基本惊喜修复期间，通过电离辐射产生的聚集损害可能会转换为致命的双链断裂。我们的结果是，线粒体蛋白中更多的HOGG1的过表达增强了对伽马射线的敏感性，这表明双链断裂也是通过线粒体基因组中流产的基础意外修复引起的双链断裂。（2）电离辐射和活性氧对DNA产生各种类型的氧化损伤，从而导致细胞突变。细菌和真核生物具有DNA修复系统以防止突变。氧化基本损坏主要通过基本惊喜修复（BER）机制来修复。但是，没有迹象表明氧化损伤直接在DNA链上反转。在这项研究中，我们检查了在DNA链上是否直接逆转氧化损伤。我们使用了用伽马射线和TSUBSUBABSUB辐照的Pub3质粒，并用还原剂Dithiolthreitol（DTT）处理。用pub3转化大肠杆菌细胞。结果，未经DTT处理，用DTT处理的PUB3的转化效率高于Pub3。我们目前正在研究Pub3的突变光谱。较少的