Parkinson's disease (PD) is a common neurodegenerative disease caused by genetic and environmental factors. We analyzed induced pluripotent stem cell (iPSC)-derived neural cells from PD patients and presymptomatic individuals carrying mutations in the PINK1 and LRRK2 genes, and healthy control subjects. We measured several aspects of mitochondrial responses in the iPSC-derived neural cells including production of reactive oxygen species, mitochondrial respiration, proton leakage and intraneuronal movement of mitochondria. Cellular vulnerability associated with mitochondrial function in iPSC-derived neural cells from PD patients and at-risk individuals could be rescued with coenzyme Q10, rapamycin or the LRRK2 kinase inhibitor GW5074. Analysis of mitochondrial responses in iPSC-derived neural cells from PD patients carrying different mutations provides insights into convergence of cellular disease mechanisms between different familial forms of PD and highlights the importance of oxidative stress and mitochondrial dysfunction in PD.

Parkinson’s disease (PD) is a progressive neurodegenerative disease that causes a debilitating movement disorder. While most cases of PD appear to be sporadic, rare Mendelian forms have provided tremendous insight into disease pathogenesis. Accumulating evidence suggests that impaired mitochondria underpin PD pathology. In support of this theory, data from multiple PD models has linked PINK1 and parkin, two recessive PD genes, in a common pathway impacting mitochondrial health, prompting a flurry of research to identify their mitochondrial targets. Recent work has focused on the role of PINK1 and parkin in mediating mitochondrial autophagy (mitophagy), however, emerging evidence casts parkin and PINK1 as key players in multiple domains of mitochondrial health and quality control.

Mutations in PTEN-induced putative kinase 1 (PINK1) and parkin cause autosomal-recessive Parkinson’s disease through a common pathway involving mitochondrial quality control. Parkin inactivation leads to accumulation of the parkin interacting substrate (PARIS, ZNF746) that plays an important role in dopamine cell loss through repression of proliferator-activated receptor gamma coactivator-1α (PGC-1α) promoter activity. Here we show that PARIS, links PINK1 and parkin in a common pathway that regulates dopaminergic neuron survival. PINK1 interacts with and phosphorylates serines 322 and 613 of PARIS to control its ubiquitination and clearance by parkin. PINK1 phosphorylation of PARIS alleviates PARIS toxicity as well as repression of PGC-1α promoter activity. Conditional knockdown of PINK1 in adult mouse brains leads to a progressive loss of dopaminergic neurons in the substantia nigra that is dependent on PARIS. Together, these results uncover a function of PINK1 to direct parkin-PARIS regulated PGC-1α expression and dopaminergic neuronal survival.