mtDNMT1介导线粒体表观遗传学调控在早衰中的作用及其干预机制

线粒体DNA甲基化和类核组装是新一代表观遗传学标志，申请者前期研究发现早衰中人胚肺成纤维细胞线粒体DNA甲基转移酶mtDNMT1表达随增龄降低，其缺陷导致线粒体转录调控因子上调，提示mtDNMT1可能介导早衰中mtDNA甲基化，但其介导mtDNA甲基化在早衰中作用未明。本项目拟应用线粒体免疫沉淀测序（mtIP-Seq）、亚硫酸氢盐修饰焦磷酸测序及5mC甲基化免疫沉淀芯片（mtMeDIP-chip）等线粒体表观遗传学技术分析早衰发生中线粒体DNA甲基化、羟甲基化及类核组装等其表观遗传学修饰的变化特征和规律；应用甲基化酶抑制剂并结合TALEN和TALEA技术干预mtDNMT1表达，探讨其介导mtDNA甲基化关键事件及在早衰中的作用。本项目不仅从线粒体表观遗传学这一崭新的视角探讨氧化应激诱导早衰的分子机制，而且为寻找线粒体早期表观遗传生物学标志及对早衰等相关疾患表观遗传靶向干预提供重要理论依据。

Mitochondrial DNA methylation and nucleoid package are the next-generation epigenetic biomarkers. Our pervious study demonstrated that the mRNA expression for mitochondria DNMT1 (mtDNMT1) decreased gradually with increased population doubling levels in human embryonic lung fibroblasts subjected to premature senescence and that the defective mtDNMT1 would up-regulate expression of mitochondrial transcriptional regulation factor for the first time, which implied that mtDNMT1 might mediate mitochondria DNA methylation in premature senescence. However, the role of mtDNA methylation mediated by mtDNMT1 in premature senescence is unclear. This proposed study will explore the epigenetic characteristics and change rules of mitochondria including mitochondrial DNA methylation, hydroxymethylation and the nucleoid package during premature senescence using specific mitochondria epigenetic methods, such as mitochondria immunoprecipitation combined sequencing (mtIP-Seq), bisulfite-PCR-pyrosequencing, 5mC mitochondria methylated DNA immunoprecipitation combined chip (mtMeDIP-chip), etc. This study is also intended to investigate the key events of mitochondrial DNA methylation mediated by mtDNMT1 and their potential role in premature senescence using the methyltransferase inhibitor, transcription activator-like effector nucleases (TALEN) and transcription activator-like effector activator (TALEA) techniques to intervene in the function of mtDNMT1. The project will not only explore the molecular mechanism underlying oxidative stress-induced premature senescence from the view point of mitochondria epigenetics, but will also help identify the early epigenetic biomarkers of mitochondrial damage, which can be exploited in the epigenetic targeted intervention of premature senescence and associated diseases.