ER Stress and Autophagic Perturbations Lead to Elevated Extracellular α-Synuclein in GBA-N370S Parkinson's iPSC-Derived Dopamine Neurons

Abstract

SummaryHeterozygous mutations in the glucocerebrosidase gene (GBA) represent the strongest common genetic risk factor for Parkinson's disease (PD), the second most common neurodegenerative disorder. However, the molecular mechanisms underlying this association are still poorly understood. Here, we have analyzed ten independent induced pluripotent stem cell (iPSC) lines from three controls and three unrelated PD patients heterozygous for the GBA-N370S mutation, and identified relevant disease mechanisms. After differentiation into dopaminergic neurons, we observed misprocessing of mutant glucocerebrosidase protein in the ER, associated with activation of ER stress and abnormal cellular lipid profiles. Furthermore, we observed autophagic perturbations and an enlargement of the lysosomal compartment specifically in dopamine neurons. Finally, we found increased extracellular α-synuclein in patient-derived neuronal culture medium, which was not associated with exosomes. Overall, ER stress, autophagic/lysosomal perturbations, and elevated extracellular α-synuclein likely represent critical early cellular phenotypes of PD, which might offer multiple therapeutic targets.

A novel real time imaging platform to quantify macrophage phagocytosis

“…For this study, hiPSCs were thawed and cultured as described in [23]. Differentiation to macrophages via embryoid body formation and directed differentiation was as previously described [24].…”

Variant U1 snRNAs are implicated in human pluripotent stem cell maintenance and neuromuscular disease

“…After 4 days, neural induction was initiated as previously described (32,40). Briefly, EBs were plated onto Geltrex-coated plates in Neural Induction medium 1 (DMEM/F12 supplemented with L-Glutamine (2 mM), N2 supplement, bovine serum albumin (BSA) (1 mg/ml), Y27632 (10 μM; Tocris), SB431542 (10 μM, Tocris), Noggin (200 ng/ml) and antibiotic/antimycotic (1% v/v)).…”

The genetic architecture of mitochondrial dysfunction in Parkinson’s disease

“…Finally, Schöndorf and colleagues observed an increased level of cytosolic Ca2+ in neurons derived from iPSC of GBA mutation carriers (Schöndorf et al 2014). Accumulation of misfolded mutant GCase into the ER leads to dysfunction of the UPR (Kurzawa-Akanbi et al 2012; Fernandes et al 2016) and can perturb ER related Ca2+ homeostasis (Kilpatrick et al 2016). The fact that GBA mutations appear as a risk factor for PD in the heterozygous state shows that one healthy allele may be enough to ensure normal cellular function for a certain time; however, during ageing, mutant cells cannot cope anymore with lysosomal and mitochondrial dysfunctions associated to alpha-synuclein accumulation.…”