Liu Jing, Fang Hongbo, Chi Zhenfen, Wu Zan, Wei Di, Mo Dongliang, Niu Kaifeng, Balajee Adayabalam S, Hei Tom K, Nie Linghu, Zhao Yongliang
Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.
Nucleic Acids Res. 2015 Jun 23;43(11):5476-88. doi: 10.1093/nar/gkv472. Epub 2015 May 12.
Xeroderma pigmentosum group D (XPD/ERCC2) encodes an ATP-dependent helicase that plays essential roles in both transcription and nucleotide excision repair of nuclear DNA, however, whether or not XPD exerts similar functions in mitochondria remains elusive. In this study, we provide the first evidence that XPD is localized in the inner membrane of mitochondria, and cells under oxidative stress showed an enhanced recruitment of XPD into mitochondrial compartment. Furthermore, mitochondrial reactive oxygen species production and levels of oxidative stress-induced mitochondrial DNA (mtDNA) common deletion were significantly elevated, whereas capacity for oxidative damage repair of mtDNA was markedly reduced in both XPD-suppressed human osteosarcoma (U2OS) cells and XPD-deficient human fibroblasts. Immunoprecipitation-mass spectrometry analysis was used to identify interacting factor(s) with XPD and TUFM, a mitochondrial Tu translation elongation factor was detected to be physically interacted with XPD. Similar to the findings in XPD-deficient cells, mitochondrial common deletion and oxidative damage repair capacity in U2OS cells were found to be significantly altered after TUFM knock-down. Our findings clearly demonstrate that XPD plays crucial role(s) in protecting mitochondrial genome stability by facilitating an efficient repair of oxidative DNA damage in mitochondria.
着色性干皮病D组（XPD/ERCC2）编码一种ATP依赖性解旋酶，该酶在核DNA的转录和核苷酸切除修复中均发挥重要作用，然而，XPD是否在线粒体中发挥类似功能仍不清楚。在本研究中，我们首次证明XPD定位于线粒体内膜，并且氧化应激下的细胞显示XPD向线粒体区室的募集增强。此外，XPD抑制的人骨肉瘤（U2OS）细胞和XPD缺陷的人成纤维细胞中线粒体活性氧的产生以及氧化应激诱导的线粒体DNA（mtDNA）常见缺失水平均显著升高，而mtDNA的氧化损伤修复能力则明显降低。采用免疫沉淀-质谱分析来鉴定与XPD相互作用的因子，检测到线粒体Tu翻译延伸因子TUFM与XPD存在物理相互作用。与XPD缺陷细胞中的发现相似，TUFM敲低后，U2OS细胞中的线粒体常见缺失和氧化损伤修复能力也发生了显著改变。我们的研究结果清楚地表明，XPD通过促进线粒体中氧化性DNA损伤的有效修复，在保护线粒体基因组稳定性方面发挥关键作用。
