Pathogenic protein aggregates are a hallmark neuropathologic finding in many neurodegenerative diseases. Most research has thus far focused on how these pathogenic aggregates are formed. However, little is known about the mechanism by which aggregates spread from cell to cell, a hallmark of neurodegenerative disease progression. Parkinson's disease (PD) is the second most common neurodegenerative disease. Mutations in the gene glucosidase beta acid 1 (GBA), which encodes a lysosomal enzyme producing ceramide, are the strongest genetic risk factor for PD. Recently, GBA mutations were also found to associate with accelerated cognitive and motor symptom progression, suggesting that GBA mutations influence the spread of protein aggregates within the brain. Recent work in PD and other neurodegenerative diseases suggest that dysregulation of lipid metabolism, and in particular ceramide, also has an important role in pathogenesis. Our recent work revealed a novel function for GBA in regulating extracellular vesicle (EVs) formation and cargo. I hypothesize that GBA deficiency mediates faster propagation of protein aggregates from cell to cell through dysregulation of EVs. To investigate the mechanisms by which GBA mutations influence the propagation of protein aggregates between tissues and between cells, I will use Drosophila, mouse and human neuronal cell culture models of GBA deficiency. I hypothesize that decreased ceramide levels due to GBA deficiency lead to dysregulation of EVs, which promotes the transfer of protein aggregates from cell to cell and leads to faster progression of neurodegeneration. Understanding the mechanisms underlying the prion-like propagation of protein aggregates has the potential to reveal novel therapeutic targets that could slow or halt PD and other neurodegenerative diseases characterized by the spread of pathogenic protein aggregation.
Pathogenic protein aggregates are present in most neurodegenerative diseases, and the spread of these aggregates within the brain correlates with disease progression. However, it remains poorly understood how these aggregates spread from neuron to neuron, and elucidating this process could reveal novel therapeutic targets to slow or halt neurodegeneration. This project investigates how mutations in GBA, a gene associated with faster progression of Parkinson's disease, influences propagation of protein aggregates from cell to cell in fruit fly, human neuron and mouse models of neurodegeneration.