PARK2 Mutation Causes Metabolic Disturbances and Impaired Survival of Human iPSC-Derived Neurons.

Helle Bogetofte,Pia Jensen,Brent J Ryan,Sissel I Schmidt,Matias Ryding,Laurent Roybon,Martin R Larsen,Carla Azevedo,Justyna Okarmus,Helle Waagepetersen,Christina S Worm,Lasse K Bak,Louise Ritter,Morten Meyer,Richard Wade-Martins,Michaela C Hohnholt

doi:10.3389/fncel.2019.00297

Abstract

The protein parkin, encoded by the PARK2 gene, is vital for mitochondrial homeostasis, and although it has been implicated in Parkinson’s disease (PD), the disease mechanisms remain unclear. We have applied mass spectrometry-based proteomics to investigate the effects of parkin dysfunction on the mitochondrial proteome in human isogenic induced pluripotent stem cell-derived neurons with and without PARK2 knockout (KO). The proteomic analysis quantified nearly 60% of all mitochondrial proteins, 119 of which were dysregulated in neurons with PARK2 KO. The protein changes indicated disturbances in oxidative stress defense, mitochondrial respiration and morphology, cell cycle control, and cell viability. Structural and functional analyses revealed an increase in mitochondrial area and the presence of elongated mitochondria as well as impaired glycolysis and lactate-supported respiration, leading to an impaired cell survival in PARK2 KO neurons. This adds valuable insight into the effect of parkin dysfunction in human neurons and provides knowledge of disease-related pathways that can potentially be targeted for therapeutic intervention.

Highlights

Parkinson’s disease (PD) is an incurable neurodegenerative disorder characterized by the progressive loss of midbrain dopaminergic neurons and subsequent striatal dopamine depletion
We report for the first time the investigation of mitochondriaspecific proteomic and phospho-proteomic changes caused by parkin dysfunction in human induced pluripotent stem cells (iPSCs)-derived neurons
To explore the effects of parkin dysfunction, we utilized two isogenic iPSC lines created from a healthy control iPSC line, where deletions have been introduced in exon 2 on both alleles of the PARK2 gene by genome editing (Shaltouki et al, 2015)

Summary

Introduction

Parkinson’s disease (PD) is an incurable neurodegenerative disorder characterized by the progressive loss of midbrain dopaminergic neurons and subsequent striatal dopamine depletion. Key contributions to the pathogenesis of both sporadic and familial PD come from mitochondrial dysfunction and oxidative stress (Abou-Sleiman et al, 2006; Ryan et al, 2015). This is supported by studies demonstrating that toxins inhibiting the mitochondrial respiratory chain complex I produce PD pathogenesis in both humans and animal models by elevating the production of reactive. PARK2 encodes the ubiquitin E3 ligase, parkin, which is recruited to damage mitochondria by PINK1. The study of parkin dysfunction in PD pathogenesis is, impeded by the fact that genetic parkin knockout (KO) rodents show only minor disease phenotypes and limited pathology (Kitada et al, 2009; Oliveras-Salvá et al, 2011)

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Conclusion