Mitochondria Bound to Lipid Droplets: Where Mitochondrial Dynamics Regulate Lipid Storage and Utilization

The isolation and biochemical characterization of lipid droplet (LD)-associated mitochondria revealed the capacity of the cell to produce and maintain distinct mitochondrial populations carrying disparate proteome and dissimilar capacities to oxidize fatty acids and pyruvate. With mitochondrial motility being a central parameter determining mitochondrial fusion, adherence to LDs provides a mechanism by which peridroplet mitochondria (PDM) remain segregated from cytoplasmic mitochondria (CM). The existence of metabolically distinct subpopulations provides an explanation for the capacity of mitochondria within the individual cell to be involved simultaneously in fatty acid oxidation and LD formation. The mechanisms that deploy mitochondria to the LD and the dysfunctions that result from unbalanced proportions of PDM and CM remain to be explored. Understanding the roles and regulation of mitochondrial tethering to LDs offers new points of intervention in metabolic diseases. Benador et al. describe the arrest of mitochondrial motility and fusion as a mechanism by which mitochondria segregate and develop specialized proteome and metabolic capacity within the same cell. Specialized mitochondrial subpopulations explain how a single cell can be involved simultaneously in fatty acid oxidation and lipid droplet formation.