Energetic and Dynamic: How Mitochondria Meet Neuronal Energy Demands

Mitochondria are the power houses of the cell, but unlike the static structures portrayed in textbooks, they are dynamic organelles that move about the cell to deliver energy to locations in need. These organelles fuse with each other then split apart; some appear anchored and others more free to move around, and when damaged they are engulfed by autophagosomes. Together, these processes—mitochondrial trafficking, fusion and fission, and mitophagy—are best described by the term “mitochondrial dynamics”. The molecular machineries behind these events are relatively well known yet the precise dynamics in neurons remains under debate. Neurons pose a peculiar logistical challenge to mitochondria; how do these energy suppliers manage to traffic down long axons to deliver the requisite energy supply to distant parts of the cell? To date, the majority of neuronal mitochondrial dynamics studies have used cultured neurons, Drosophila larvae, zebrafish embryos, with occasional experiments in resting mouse nerves. However, a new study in this issue of PLOS Biology from Marija Sajic and colleagues provides an in vivo look at mitochondrial dynamics along resting and electrically active neurons of live anaesthetized mice.