Mitochondrion at the crossroads between nutrients and the epigenome

The modulation of gene expression is a pivotal regulatory mechanism by which cells adapt to endogenous and exogenous stimuli, including nutrition. In this context, the epigenome (i.e., the collection of biochemical modifications to the genome that do not affect the DNA sequence but determine whether genes are switched on or off) represents a crucial modulator of gene expression, with epigenetic modifications being finely tuned by extracellular and intracellular signals. At the same time, cellular responses to environmental cues are mediated, at least in part, by the mitochondria, that regulate both energetic and redox homeostasis. Recently, a tight link between epigenetic and mitochondrial metabolism has been described. This relationship is further supported by the fact that mitochondria contain their own DNA, which is a circular double-stranded molecule, present in multiple copies in each mitochondrion and that also undergo epigenetic modifications. Moreover, a pivotal role of nutrition in affecting both epigenetic and mitochondrial dynamics and function has been highlighted. While the role of nutrition in modulating mitochondrial functions is extensively discussed in other sections of this book, this chapter will focus on the impact of nutrition in boosting epigenetic regulations and on the role of the mitochondria in mediating this complex relationship.