Global DNA methylation levels are modulated by mitochondrial DNA variants

Aim: In the present study, we investigated whether global DNA methylation levels are affected by mitochondrial DNA (mtDNA) variants, which are known to modulate mitochondrial functions. Materials & methods: Global DNA methylation levels were evaluated in peripheral blood DNA collected from adult subjects and in vitro using the DNA of cybrid cells harboring mtDNAs of different haplogroups. In these cells, mRNA expression of genes involved in DNA methylation processes, and ATP and reactive oxygen species levels were also analyzed. Results: The analysis revealed that methylation levels were higher in the subjects carrying the 1 haplogroup than in non-1 carriers. Consistently, cybrids with 1 haplogroup mtDNA showed higher methylation levels than other cybrids. Interestingly, we observed overexpression of the MAT1A gene and low ATP and ROS levels in 1 cybrids. Conclusion: Our findings indicate that mtDNA-specific interactions between mitochondria and the nucleus regulate epigenetic changes, possibly by affecting oxidative phosphorylation efficiency.