Table 1.
An overview of current studies of mitochondrial epigenetics in disease.
| Research question | Techniques | Main findings | Ref. |
|---|---|---|---|
| The effect of different environmental exposures (metal-rich particulate matter, air benzene levels and traffic-derived elemental carbon levels) on mitochondria | Pyrosequencing; qRT-PCR | Increased exposure to particulate matter increases MT-RNR1 and MT-TF gene methylation. Increased MT-RNR1 methylation is associated with a significant increase in mtDNA copy number | [52] |
| The effect of mtDNA methylation in the mitochondrial D-loop on gene expression in colorectal cancer cells | Methylation-specific PCR; western blotting | An increased level of demethylated sites in the D-loop of tumor cells is strongly associated with increased MT-ND2 expression and mtDNA copy number | [48] |
| The effect of methylation in the D-loop, MT-ND6 and MT-CO1 on disease progression in SS and NASH | Methylation-specific PCR; qRT-PCR | Increased MT-ND6 methylation and decreased MT-ND6 protein levels in NASH compared with SS. Physical activity reduced MT-ND6 methylation in NASH | [53] |
| The effect of decreased SAM on mtDNA methylation in Down's syndrome lymphoblastoid cells | LC-ESI-MS; LC-MS/MS | Decreased SAM availability in Down's syndrome lymphoblastoid cells reduce methyl uptake to mitochondria and lead to mtDNA hypomethylation | [54] |
| The tissue specificity of DNMTs and 5-mC in the mitochondria in relation to ALS models | IF; pyrosequencing | Increased methylation at six cytosine sites in the 16S rRNA gene in the spinal cord of an ALS mouse cell line. Reduced levels of mtDNMT3a protein in skeletal muscle and spinal cord early in disease | [55] |
| The effect of mtDNA methylation on mtDNA copy number in gastric cancer | qRT-PCR; pyrosequencing | Reduced mtDNA copy number levels in late clinicopathological stages. Demethylation of mtDNA increases mtDNA copy number | [56] |
ALS: Amyotrophic lateral sclerosis; IF: Immunofluorescence; LC–ESI-MS/MS: Liquid chromatography–electrospray ionization tandem mass spectrometry; LC–MS: Liquid chromatography mass spectrometry; mtDNA: Mitochondrial DNA; NASH: Nonalcoholic steatohepatitis; qRT-PCR: Quantitative real-time PCR; SAM: S-Adenosylmethionine; SS: Simple steatosis.