EFFECTS OF GBA1 MUTATIONS ON NEURONAL EXCITABILITY, ULTRASTRUCTURE, AND VGLUT2 AND CRYAB EXPRESSION IN PARKINSON’S DISEASE DOPAMINERGIC NEURONS

Mutations in the glucocerebrosidase 1 (GBA1) gene are major risk factors for Parkinson´s disease (PD), but their role in PD etiopathology is not fully understood. The impact of GBA1 mutations on neuronal maturation, function and degeneration was investigated in dopaminergic (DA) neurons obtained from induced pluripotent stem cells (iPS cells/iPSCs) derived from PD patients carrying the heterozygous N370S or L444P mutation in GBA1. DA neurons co-expressing TH and VGLUT2 were detected in the cultures, and their percentage was markedly reduced in L444P GBA1 cultures compared to controls. Remarkably, neurons carrying either GBA1 mutation accumulated abundant Lewy body-like inclusions, multilamellar bodies, and a vacuolated Golgi apparatus. Electrophysiological recordings revealed a significant increase in the firing rate of N370S but not L444P neurons; this phenotype correlated with a significant accumulation of α-synuclein and phospho-α-synuclein inclusions in N370S neurons. Notably, a significant upregulation of the molecular chaperone CRYAB was found early in N370S neuron differentiation and in the substantia nigra of PD patients. In conclusion, our cellular model allows clear features of neurodegeneration to be detected in neurons derived from PD patients. Our findings indicate that N370S and L444P GBA1 mutations produce common and distinct molecular, ultrastructural, and functional changes, possibly involved in PD etiopathology. They suggest that VGLUT2 and CRYAB may be investigated as potential early molecular targets and biomarkers in GBA1-PD. Finally, we will present an outline of our current study on the mechanisms of neurodegeneration and neurorepair in PD using brain organoid models.