AMPK: a master regulator of mitochondrial quality and quantity

The AMP-activated protein kinase (AMPK) may have arisen soon after the endosymbiosis event that generated eukaryotes, perhaps to allow the archaeal host to communicate its requirements for ATP to the bacterial endosymbionts that became mitochondria. Consistent with this, AMPK is now known to regulate most aspects of the mitochondrial life cycle. It drives fragmentation of the network by promoting fission and inhibiting fusion, increasing mitochondrial number while allowing isolation of dysfunctional fragments from the network. It promotes the biogenesis of new mitochondrial components while also regulating mitophagy, promoting the degradation of dysfunctional mitochondria and inhibiting the removal of functional mitochondria. We will discuss these new findings and propose that the regulation of mitochondria was an ancient function of AMPK originating in the early eukaryote.