Oxygen-induced DNA damage and its repair mechamism

氧诱导的DNA损伤及其修复机制

基本信息

批准号：
10044304
负责人：
TSUZUKI Teruhisa
金额：
$ 4.48万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10044304/
关键词：
Reactive oxygen Oxidative stress Mutation Carcinogenesis 8-oxo-guanine Tumor suppressor gene DNA repair 2-OH-dATP 8ーオキソグアニン DNA修飾 2ーOH-dATP 活性酵素 β-オキソグアニンアポトーシス神経細胞死

项目摘要

Oxygen radicals, which can be produced through normal cellular metabolism, are thought to play an important role in mutagenesis and tumorigenesis. Among various classes of oxidative DNA damage, 8-oxo-7,8-dihydroguanine (8-oxoG) is most important because of its abundance and mutagenicity.The MTH1 gene encodes an enzyme that hydrolyzes 8-oxo-dGTP to monophosphate in the nucleotide pool, thereby preventing occurrence of transversion mutations. By means of gene targeting, we have established MTH1 gene-knockout cell lines and mice. When examined 18 months after birth, a greater number of tumors were formed in the lungs, livers and stomachs of MTH1-deficient mice, as compared with wild-type mice. The MTH1-deficient mouse will provide a useful model for investigating the role of the MTH1 protein in normal conditions and under oxidative stress.Recent studies showed that the human MTH1 protein hydrolyzed 2-hydroxy-dATP more efficiently and with higher affinity than 8-oxo-dGTP.Current studies on mutagenesis with MTH1-null mutant mice will provide more insight into the role of the sanitizing enzyme, MTH1.We found a single nucleotide polymorphism in human MTH1 gene which alters splicing patterns of its transcripts, and that a novel MTH1 polypeptide with an additional mitochondrial targeting signal is produced from the altered MTH1 mRNA.We further characterized expression and intracellular localization of 8-oxoG DNA glycosylase (OGG1) and 2-OH-A/adenine DNA DNA glycosylase (MYH) in human cells. The authentic OGG1 and MYH proteins present in mitochondria as well as in nuclei, and their intracellular localization were found to be regulated by alternative splicing of each transcript.

氧自由基可以通过正常细胞代谢产生，被认为在诱变和肿瘤发生中发挥重要作用。在各种类型的氧化性 DNA 损伤中，8-oxo-7,8-二氢鸟嘌呤 (8-oxoG) 由于其丰度和致突变性而最为重要。MTH1 基因编码一种酶，可将核苷酸中的 8-oxo-dGTP 水解为单磷酸盐库，从而防止颠换突变的发生。通过基因打靶，我们建立了MTH1基因敲除细胞系和小鼠。出生后 18 个月进行检查时发现，与野生型小鼠相比，MTH1 缺陷小鼠的肺、肝和胃中形成了更多的肿瘤。 MTH1缺陷小鼠将为研究MTH1蛋白在正常条件下和氧化应激下的作用提供有用的模型。最近的研究表明，人类MTH1蛋白比8-oxo更有效地水解2-羟基-dATP，并且具有更高的亲和力-dGTP。目前对 MTH1 缺失突变小鼠的诱变研究将提供对消毒酶 MTH1 作用的更多见解。我们在人类中发现了单核苷酸多态性MTH1 基因改变其转录物的剪接模式，并且从改变的 MTH1 mRNA 产生具有额外线粒体靶向信号的新型 MTH1 多肽。我们进一步表征了 8-oxoG DNA 糖基化酶 (OGG1) 和 2-OH 的表达和细胞内定位-A/人类细胞中的腺嘌呤 DNA DNA 糖基化酶 (MYH)。真正的 OGG1 和 MYH 蛋白存在于线粒体和细胞核中，并且发现它们的细胞内定位受到每个转录物的选择性剪接的调节。