Protein phosphatase PTC7 homolog
protein serine/threonine phosphatase activity
The mitochondrial phosphatase PPTC7 orchestrates mitochondrial metabolism regulating coenzyme Q<sub>10</sub> biosynthesis.
Coenzyme Q<sub>10</sub> (CoQ<sub>10</sub>) is a redox molecule critical for the proper function of energy metabolism and antioxidant defenses. Despite its essential role in cellular metabolism, the regulation of CoQ<sub>10</sub> biosynthesis in humans remains mostly unknown. Herein, we determined that PPTC7 is a regulatory protein of CoQ<sub>10</sub> biosynthesis required for human cell survival. We demonstrated by in vitro approaches that PPTC7 is a bona fide protein phosphatase that dephosphorylates the human COQ7. Expression modulation experiments determined that human PPTC7 dictates cellular CoQ<sub>10</sub> content. Using two different approaches (PPTC7 over-expression and caloric restriction), we demonstrated that PPTC7 facilitates and improves the human cell adaptation to respiratory conditions. Moreover, we determined that the physiological role of PPTC7 takes place in the adaptation to starvation and pro-oxidant conditions, facilitating the induction of mitochondrial metabolism while preventing the accumulation of ROS. Here we unveil the first post-translational mechanism regulating CoQ<sub>10</sub> biosynthesis in humans and propose targeting the induction of PPTC7 activity/expression for the treatment of CoQ<sub>10</sub>-related mitochondrial diseases.