Comparative analysis of human mitochondrial methylomes shows distinct patterns of epigenetic regulation in mitochondria

DNA methylation and histone modifications across the nuclear genome have been extensively analyzed, but the epigenetic modifications associated with the mitochondrial genome have not yet been analyzed at high resolutions. In the present work, we analyzed methyl-cytosine profiles from methylated DNA immunoprecipitation datasets from 39 different human cell and tissue types from the NIH Roadmap Epigenomics project and validated the data using an orthologous bisulfite sequencing dataset. We observe a distinct distribution of zmethyl-cytosine in mitochondrial genomes which are conserved across all cell and tissue types. This study thus describes the first comprehensive map of methyl cytosines across the human mitochondrial genome.