Evaluation of Induced Pluripotent Stem Cell-Derived Dopaminergic Neurons from Siblings with Gaucher Disease Discordant for Parkinsonism

Abstract

Background: In Gaucher disease (GD), glucocerebrosidase (GCase) deficiency results from biallelic pathogenic GBA1 variants. While GBA1 variants are a major risk factor for Parkinson's disease (PD), most patients with GD never develop parkinsonism.

Objectives: To understand factors impacting PD penetrance in patients with GD by comparing induced pluripotent stem cell (iPSC)-derived dopaminergic neurons (DANs) from GD siblings discordant for PD.

Methods: iPSCs, reprogrammed from two different sibling pairs where both siblings had GD but only one developed PD, were differentiated into DANs. In one family, DAN enrichment was achieved via geneticin selection and proteomic evaluations were performed.

Results: GCase and lipid substrate levels were similar in GD and GD/PD DANs. After geneticin selection, proteomic analysis of the enriched DANs showed upregulation of molecular chaperones in the GD/PD line.

Conclusion: PD discordance in both sets of GD siblings did not correlate with GCase or lipid substrate levels in DANs, implicating the involvement of other modifiers. Published 2025. This article is a U.S. Government work and is in the public domain in the USA. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Keywords: GBA1; Gaucher disease; Parkinson's disease; dopaminergic neuron differentiation; neurodegeneration.

FIG 1

Characterization of patient‐induced pluripotent stem cell (iPSC)‐derived dopaminergic neurons (DANs). (A) Summary of the clinical features of each iPSC donor. (B,C) Western blot showing levels of glucocerebrosidase (GCase), tyrosine hydroxylase (TH), and glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) in the five lines of DANs with quantification. (D) GCase activity levels in DANs from the five lines. (E) Glucosylceramide (GluCer) and glucosylsphingosine (GluSph) levels in HT707, HT708, and HT711 DANs. The indicated values are the average from three independent measurements from biological replicates (unit: ×10⁻¹ pmole/per nmole phosphate). DX, diagnosis; N/A, not applicable; M, male; F, female; ERT, enzyme replacement therapy. [Color figure can be viewed at wileyonlinelibrary.com]

FIG. 2

Phenotyping enriched dopaminergic neurons (DANs). (A) Western blotting analysis of enriched DANs from HT707 TH‐neo, HT708 TH‐neo, and HT711 TH‐neo showing tyrosine hydroxylase (TH), α‐synuclein (α‐syn), glucocerebrosidase (GCase), and glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) as the loading control. (B) Uniform Manifold Approximation and Projection (UMAP) clustering DAN cellular proteomics shows improved comparability after geneticin selection. (C) A network of lysosomal hydrolases that is downregulated in HT707 TH‐neo and HT708 TH‐neo DANs. (D) A network of molecular chaperones that is upregulated in HT708 TH‐neo DANs compared with HT707 TH‐neo. (E) Top 20 enriched gene ontology (GO) term pathways comparing HT708 TH‐neo and HT707 TH‐neo DANs. [Color figure can be viewed at wileyonlinelibrary.com]