PERK-Mediated Unfolded Protein Response Activation and Oxidative Stress in PARK20 Fibroblasts.

Giuseppina Amodio,Lucrezia Zerillo,Giuseppe De Michele,Anna De Rosa,Marco Oliveti,Maurizio Renna,Maria Teresa Pellecchia,Lucio Nitsch,Giovanna Maria Pierantoni,Chiara Criscuolo,Roman Polishchuk,Paolo Barone,Ornella Moltedo,Simona Paladino,Raffaella Faraonio,Vincenzo Bonifati,Paola Di Pietro,Paolo Remondelli,Elena Polishchuk,D Fasano

doi:10.3389/fnins.2019.00673

Abstract

PARK20, an early onset autosomal recessive parkinsonism is due to mutations in the phosphatidylinositol-phosphatase Synaptojanin 1 (Synj1). We have recently shown that the early endosomal compartments are profoundly altered in PARK20 fibroblasts as well as the endosomal trafficking. Here, we report that PARK20 fibroblasts also display a drastic alteration of the architecture and function of the early secretory compartments. Our results show that the exit machinery from the Endoplasmic Reticulum (ER) and the ER-to-Golgi trafficking are markedly compromised in patient cells. As a consequence, PARK20 fibroblasts accumulate large amounts of cargo proteins within the ER, leading to the induction of ER stress. Interestingly, this stressful state is coupled to the activation of the PERK/eIF2α/ATF4/CHOP pathway of the Unfolded Protein Response (UPR). In addition, PARK20 fibroblasts reveal upregulation of oxidative stress markers and total ROS production with concomitant alteration of the morphology of the mitochondrial network. Interestingly, treatment of PARK20 cells with GSK2606414 (GSK), a specific inhibitor of PERK activity, restores the level of ROS, signaling a direct correlation between ER stress and the induction of oxidative stress in the PARK20 cells. All together, these findings suggest that dysfunction of early secretory pathway might contribute to the pathogenesis of the disease.

Highlights

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (Gao and Hong, 2011; Cannon and Greenamyre, 2013; Beitz, 2014; Feng et al, 2015)
To test whether membrane trafficking from the Endoplasmic Reticulum (ER) to the Golgi complex was affected by the p.R258Q mutation, we analyzed fibroblasts derived from homozygous R258Q/R258Q PARK20 patients and from healthy individuals
ERGIC53 vesicles redistribution pattern in the PARK20 cells overlapped with the membrane network of the ER, as shown by the fluorescence detected by the anti-KDEL antibody, which label ER resident proteins bearing the KDEL retrieval sequence (Figure 1B)

Summary

Introduction

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (Gao and Hong, 2011; Cannon and Greenamyre, 2013; Beitz, 2014; Feng et al, 2015). A combination of environmental and genetic factors has been considered to concur to the neuronal death. Among genetic PD, PARK20 is a rare autosomal recessive juvenile Parkinson’s form due to mutations in Synaptojanin (Synj1), a phosphatidylinositol phosphatase (PtdInsPP) (Krebs et al, 2013; Quadri et al, 2013; Olgiati et al, 2014). The homozygous R258Q mutation was almost simultaneously reported in three unrelated families from Iran and Italy (Krebs et al, 2013; Quadri et al, 2013; Olgiati et al, 2014). A frameshift mutation (p.S552Ffs∗5) in heterozygous state with the benign p.T1236M missense variant has been identified in one late onset PD patient from Moroccan consanguineous parents (Bouhouche et al, 2017), correlating Synj lesions to the risk of PD development

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