Maintenance of the mitochondrial genome is essential for proper cellular function. For this purpose, mitochondrial DNA (mtDNA) needs to be faithfully replicated, transcribed, translated, and repaired in the face of constant onslaught from endogenous and environmental agents. Although only 13 polypeptides are encoded within mtDNA, the mitochondrial proteome comprises over 1500 proteins that are encoded by nuclear genes and translocated to the mitochondria for the purpose of maintaining mitochondrial function. Regulation of mtDNA and mitochondrial proteins by epigenetic changes and post-translational modifications facilitate crosstalk between the nucleus and the mitochondria and ultimately lead to the maintenance of cellular health and homeostasis. DNA methyl transferases have been identified in the mitochondria implicating that methylation occurs within this organelle; however, the extent to which mtDNA is methylated has been debated for many years. Mechanisms of demethylation within this organelle have also been postulated, but the exact mechanisms and their outcomes is still an active area of research. Mitochondrial dysfunction in the form of altered gene expression and ATP production, resulting from epigenetic changes, can lead to various conditions including aging-related neurodegenerative disorders, altered metabolism, changes in circadian rhythm, and cancer. Here, we provide an overview of the epigenetic regulation of mtDNA via methylation, long and short noncoding RNAs, and post-translational modifications of nucleoid proteins (as mitochondria lack histones). We also highlight the influence of xenobiotics such as airborne environmental pollutants, contamination from heavy metals, and therapeutic drugs on mtDNA methylation. Environ. Mol. Mutagen., 60:668-682, 2019. © 2019 Wiley Periodicals, Inc.

中文翻译：

---

线粒体DNA：表观遗传学和环境。

线粒体基因组的维持对于适当的细胞功能至关重要。为此，面对内源性和环境因素的不断冲击，必须忠实地复制，转录，翻译和修复线粒体DNA（mtDNA）。尽管mtDNA内仅编码13种多肽，但线粒体蛋白质组包含1500多种蛋白质，这些蛋白质由核基因编码并易位到线粒体，以维持线粒体功能。通过表观遗传学变化和翻译后修饰对mtDNA和线粒体蛋白质的调控促进了核与线粒体之间的串扰，最终导致维持细胞健康和体内平衡。已经在线粒体中鉴定出DNA甲基转移酶，暗示甲基化发生在该细胞器内。但是，mtDNA甲基化的程度已经争论了很多年。还假定了该细胞器内的脱甲基机制，但是确切的机制及其结果仍然是研究的活跃领域。由表观遗传改变导致的线粒体功能异常，其基因表达和ATP产生改变，可导致各种疾病，包括与衰老相关的神经退行性疾病，代谢改变，昼夜节律改变和癌症。在这里，我们提供了通过甲基化，长和短非编码RNA以及类核苷酸蛋白的翻译后修饰（由于线粒体缺乏组蛋白）对mtDNA进行表观遗传调控的概述。我们还强调了异种生物如空气传播的环境污染物，重金属的污染以及治疗药物对mtDNA甲基化的影响。环境。大声笑 Mutagen。，60：668-682，2019.©2019 Wiley Periodicals，Inc.