To investigate if GBA has a neuroprotective role in astrocytes.  

Mutations in the gene glucosidase, beta acid 1 (GBA) are the strongest genetic risk factor for Parkinson's Disease (PD) and accelerate disease progression. Our work using a Drosophila GBA deficient model revealed altered EVs that may accelerate spread of protein aggregates. We hypothesize that GBA may have a neuroprotective role in astrocytes in degrading pathogenic neuronal EVs that could seed and propagate Lewy pathology. 

We developed a Drosophila model of GBA deficiency (GBA^del) manifesting neurodegeneration and accelerated protein aggregation. We also generated human induced pluripotent stem cells (iPSCs) from an individual with PD carrying the IVS2+1G>A GBA mutation (GBA^IVS PD). Astrocytes were differentiated from GBA^IVS PD, isogenic GBA^WT PD, and age- and sex-matched healthy control iPSCs using StemCell Technologies reagents and protocol. Confirmation of mature astrocytes was performed by qPCR, immunocytochemistry and Fluo-4 AM calcium transience assay. Astrocytes will be exposed to neuronal EV’s isolated by size exclusion chromatography from conditioned media of GBA^IVS PD and control neurons expressing a-syn-GFP. 

Expression of wildtype dGBA1b in glia of GBA^del mutant flies rescued protein aggregation in brain. Astrocytes differentiated from GBA^IVS PD and control iPSCs express S100b, GFAP, GLAST and Aquaporin4. We are currently characterizing endocytosis and endolysosomal-trafficking in GBA^IVS PD and control astrocytes using the DQ-Red-BSA assay and immunocytochemistry for markers of endolysosomal-trafficking. 

We differentiated GBA^IVS PD and control iPSCs into mature astrocytes with similar expression profile to human primary fetal astrocytes. We anticipate that GBA^IVS PD astrocytes will have reduced neuronal EV uptake compared to controls. We also expect neurons co-cultured with GBA^IVS PD astrocytes to have increased protein aggregation and decreased survival compared to neurons co-cultured with control astrocytes. This study could reveal a novel neuroprotective role for GBA in glia to reduce propagation of pathology in neurodegeneration.