ABSTRACT

Abstract .................................................................................................................. 315 Introduction of Mitochondrial Genome Organization ........................................... 316 Epigenetics: A Brief Introduction of Epigenetic Regulation ................................. 317 Regulation of Mitochondrial Function: The Role of Epigenetic Changes ............. 319 Liver Epigenome of Human NAFLD: Epigenetic Marks in Nuclear Genes That Regulate Mitochondrial Function and Metabolism ....................................... 320 Methylation of Human Mitochondrial DNA and Its Role in NAFLD Disease Severity and Progression ........................................................................................ 321 Conclusion ............................................................................................................. 323 Acknowledgments .................................................................................................. 323 References .............................................................................................................. 324

Mitochondria have their own deoxyribonucleic acid (DNA), and this genetic material is known as mitochondrial DNA or mtDNA. In humans and most multicellular organisms in general, mtDNA is a circular DNA that spans about 16,500 base pairs and contains 37 genes, 13 of which are involved in oxidative phosphorylation [1]. A schematic of human mtDNA structure and coding genes is shown in Figure 13.1. The names of the mtDNA genes encoding proteins of the core subunit of the mitochondrial membrane respiratory chain nicotinamide adenine dinucleotide (NADH) dehydrogenase complex I are as follows: MT-ND1 (mitochondrially encoded NADH dehydrogenase 1), MT-ND2 (mitochondrially encoded NADH dehydrogenase 2), MT-ND3 (mitochondrially encoded NADH dehydrogenase 3), MT-ND4 (mitochondrially encoded NADH dehydrogenase 4), MT-ND4L (mitochondrially encoded

FIGURE 13.1 (See color insert.) Map of the human mitochondrial DNA. (From MITOWEB, MITOMAP: A human mitochondrial genome database, 2013, https://www.mitomap.org.)

NADH dehydrogenase 4L), MT-ND5 (mitochondrially encoded NADH dehydrogenase 5), and MT-ND6 (mitochondrially encoded NADH dehydrogenase 6).