Mitochondrial DNA Methylation: Existence, Localization, and Function

Epigenetic regulation of gene expression is an intensively studied area of molecular biology. It includes cytosine methylation, whose mechanism of action in nuclear DNA is relatively well understood. This process is mediated by enzymes from the DNA methyltransferase family. Hydroxymethylation is, considered both an intermediate step in cytosine demethylation and a potentially independent mechanism of regulation of gene expression. Functional significance—and even the presence—of methylation within mitochondrial DNA (mtDNA) remains a matter of debate. Accumulated evidence indicates that methylation and hydroxymethylation may play important role in mitochondria. Although epigenetic regulation of gene expression in mitochondria is not yet fully understood, the current state of knowledge suggests that it may influence proper cellular function and the pathogenesis of numerous diseases.