hOGG1基因在Cr(Ⅵ)诱导线粒体DNA氧化损伤中的作用

目的探讨hOGG1基因在Cr(Ⅵ)诱导线粒体DNA氧化损伤中的修复作用。方法取不同浓度的Cr(Ⅵ)(0、2、8和32μmol/L)处理L-02肝细胞24h,分别测定细胞内活性氧簇(ROS)与hOGG1 mRNA表达水平和线粒体内8-羟基脱氧鸟苷(8-OHdG)与hOGG1基因表达的人类8-羟基鸟嘌呤DNA糖苷酶蛋白(hOGG1蛋白)水平。结果 8μmol/L和32μmol/L剂量组与对照组比较,细胞内ROS平均水平及线粒体内8-OhdG平均水平均明显增加(P<0.05),而hOGG1基因mRNA水平和线粒体内hOGG1蛋白水平,与对照组比较,2μmol/L剂量组两者水平均上升(P<0.05),32μmol/L剂量组两者水平均降低(P<0.05)。结论 Cr(Ⅵ)可诱导细胞内ROS水平增加,引起线粒体DNA氧化损伤,而hOGG1基因表达水平的改变,影响了线粒体DNA的修复能力。hOGG1基因在Cr(Ⅵ)诱导线粒体DNA氧化损伤中起到了重要的作用。

Effect of hOGG1 gene on the oxidative damage of mitochondrial DNA induced by hexavalent chromium

Objective To explore the effect of hOGG1 gene on the repair capability of oxidative damage in mitochondrial DNA induced by hexavalent chromium(Cr(Ⅵ)).Methods After incubating with Cr(Ⅵ)at the concentrations of 2,8,32 μmol/L for 24 hours,mitochondria from L-02 hepatocytes were collected.Cellular ROS and hOGG1 mRNA and mitochondrial 8-OHdG and hOGG1 protein in L-02 hepatocytes were examined by Fluorometric Assay Kit,RT-qPCR,8-OHdG ELISA Kit and western blot respectively.Results Compared with the control group,the levels of cellular ROS and mitochondrial 8-OHdG in 8 and 32μmol/L Cr(Ⅵ)treated groups were significantly increased(P<0.05).The levels of cellular hOGG1 mRNA and mitochondrial hOGG1 protein in 2μmol/L Cr(Ⅵ)treated group were increased significantly(P<0.05),but decreased in 32μmol/L group(P<0.05).Conclusion Overproduction of cellular ROS could be induced by Cr(Ⅵ)and could result in genomic DNA oxidative damage,and the lower expression of cellular hOGG1 gene could decrease the repair capability of mitochondrial DNA.Therefore,the cellular hOGG1 gene exerted important effect in the repair of mitochondrial DNA oxidative damage induced by Cr(Ⅵ).