Objective: To characterize how GBA1 deficiency alters endolysosomal trafficking in astrocytes versus neurons.

Background: Mutations in the gene glucosidase, beta acid 1 (GBA1) not only increase risk for Parkinson’s Disease (PD) but also accelerate disease progression. Our Drosophila GBA1 deficient model suggests a mechanisms underlying the faster clnical progression whereby altered exosomes act as vehicles to accelerate pathogenic protein aggregate spread. Restoring wildtype glucocerebrosidase activity in glia reduced protein aggregation in brain, leading us to examine the endolysosomal pathway and exosome biogenesis in neurons versus astrocytes.

Method: Human induced pluripotent stem cells (iPSCs) were generated from an individual with PD carrying the IVS2+1G>A GBA mutation (GBA^IVS PD). Neurons and astrocytes were differentiated from GBA^IVS PD, isogenic GBA^WT PD, and age- and sex-matched healthy control iPSCs. Immunocytochemistry of different stages of endolysosomal trafficking were imaged in iPSC-derived astrocytes and neurons 14 days post differentiation by confocal microscopy. Imaris software was used to 3D reconstruct z-stacks and obtain volumetric measurements of stained endolysosomal vesicles.

Results: GBA^IVS PD dopaminergic neurons were found to have enlarged early endosome and lysosome compartments compared to controls, but no significant differen in late endosomes. There is no significant difference in early endosomes between GBA^IVS PD and control astrocytes. However, late endosomes and lysosomes are larger in size in GBA^IVS PD astrocytes compared to control, although the overall compartments of late endosomes and lysosomes are not significantly altered between GBA^IVS PD and control astrocytes.

Conclusion: Data from our iPSC-derived neurons and astrocytes indicate GBA1 deficiency influences endolysosomal trafficking differently in astrocytes versus neurons. We are now confirming these differential alterations in live imaging of astrocytes and neurons, and examining whether wildtype GBA1 function in astrocytes may be neuroprotective in slowing propagation of pathogenic protein aggregation in neurons, given the differential effects among cell types.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gba1-deficiency-differentially-affects-endolysosomal-trafficking-in-neurons-and-astrocytes/