Epigenetics can be explored at different levels and can be divided into two major areas: epigenetics of nuclear-encoded DNA and epigenetics of mitochondrial-encoded DNA. In epigenetics of nuclear-encoded DNA, the main roles are played by DNA methylation, changes in histone structure and several types of non-coding RNAs. Mitochondrial epigenetics seems to be similar in the aspect of DNA methylation and to some extent in the role of non-coding RNAs but differs significantly in changes in components coiling DNA. Nuclear DNA is coiled around histones, but mitochondrial DNA, together with associated proteins, is located in mitochondrial pseudocompartments called nucleoids. It has been shown that mitochondrial epigenetic mechanisms influence cell fate, transcription regulation, cell division, cell cycle, physiological homeostasis, bioenergetics and even pathologies, but not all of these mechanisms have been explored in stem cells. The main issue is that most of these mechanisms have only recently been discovered in mitochondria, while improvements in methodology, especially next-generation sequencing, have enabled in-depth studies. Because studies exploring mitochondria from other aspects show that mitochondria are crucial for the normal behavior of stem cells, it is suggested that precise mitochondrial epigenetics in stem cells should be studied more intensively.
Keywords: Epigenetics; Mitochondria; Mitochondrial DNA; Stem cell.