neurodegenerative disorder, α-synuclein constructs, yeast strains, yeast expression, Western analysis, growth curve analysis, GFP microscopy
The neurodegeneration pathology in Parkinson’s disease patients predominantly targets dopaminergic neurons in the midbrain. These neurons accumulate aggregated alpha-synuclein, which may be linked to cell death. The misfolding and buildup of α-synuclein is thought to trigger its accumulation and aggregation. An attractive hypothesis states that excess amounts of α-synuclein are due to dysfunctional degradation of the protein. Until recently, the proteasome was considered the major site for degrading alpha-synuclein, but recent studies suggest that the lysosome may also be involved. To test this latter hypothesis, we employed a budding yeast model for α-synuclein aggregation and toxicity to genetically evaluate the role of the multivesicular body (MVB) pathway, which is a major route used by proteins to target the yeast vacuole for degradation. ESCRT-1 is a major protein complex in the MVB pathway. We asked whether alpha-synuclein would accumulate and increase toxicity in yeast that lacked important ESRCT-1 components, in this case vps28 or mvb12. We demonstrate that the absence of vps28 altered wildtype, A53T, and E46K α-synuclein localization. Specifically,ƒn α-synuclein shifted from being localized primarily on the plasma membrane to being diffuse and aggregated within the cytoplasm. In contrast, the mvb12∆ strain retained plasma membrane α-synuclein localization. Our preliminary data indicates that the MVB pathway is involved in α-synuclein degradation, but not all proteins within ESRCT-1 participate. Complete analysis of the remaining ESCRT-I proteins and other ESCRT complexes is needed to fully understand the role of sorting proteins and MVBs in the α-synuclein lysosome degradation pathway.
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