Loss of ATP13A2 impairs glycolytic function in Kufor-Rakeb syndrome patient-derived cell models

Abstract

Background: Kufor-Rakeb syndrome (KRS) is an autosomal recessive, juvenile-onset Parkinson's disease (PD) caused by loss-of-function mutations in ATP13A2 (PARK9). Impaired energy metabolism is considered a pathogenic mechanism in PD and mitochondrial dysfunction resulting from Zn(2+) dyshomeostasis has been found in KRS patient-derived cells. In addition to mitochondrial energy production, glycolysis plays an important role in cellular energy metabolism and glucose hypometabolism has been reported in PD. However, glycolytic status in KRS remains undetermined despite its potential importance.

Methods: We assessed glycolytic function in ATP13A2-deficient KRS patient-derived human olfactory neurosphere cells and fibroblasts and determined the effect of pyruvate supplementation on improving cellular energy production.

Results: We found impaired extracellular acidification, reduction in pyruvate production and a decrease in the NAD(+)/NADH ratio, indicative of glycolytic dysfunction. In addition, gene expression analysis revealed an altered expression profile for several glycolytic enzymes. Glycolytic dysfunction was aggravated when the intracellular Zn(2+) concentration was increased, while ATP13A2 overexpression and pyruvate supplementation blocked the observed Zn(2+)-mediated toxicity. Moreover, supplementation with pyruvate significantly increased basal mitochondrial ATP production and abolished Zn(2+)-induced cell death.

Conclusions: These findings indicate that glycolytic dysfunction contributes to pathogenesis and pyruvate supplementation improves overall cellular bioenergetics in our KRS patient-derived cell model, highlighting a therapeutic potential.

Keywords: ATP13A2; Glycolysis; Kufor-Rakeb syndrome; Pyruvate; Zinc.