Research data has recently indicated that pathology in Parkinson’s disease (PD) starts at the synapse, the part of the neurons where the release of dopamine occurs, dysfunction of which leads to neuronal death via a “dying back” process. We aim to determine whether increased levels of cysteine string protein alpha (CSPalpha), a chaperon protein involved in the assembly of a protein complex called SNARE, involved in the release of neurotransmitters like dopamine, will be able to rescue the abnormal dopamine release observed in pre-clinical models of early stages of PD.
Alpha-synuclein, the main protein that forms the Lewy bodies that are the characteristic protein aggregate present in patients with PD, is accumulated at the site of connection between nerve cells, or synapses, in the striatum of our pre-clinical model, which represents early stages of PD pathology. This accumulation is associated with the re-distribution of components of the SNARE complex (proteins that are crucial in maintaining neurotransmitter release machinery), and progressive, age-dependent reduction of dopamine release from the striatum. Chaperon proteins (e.g. CSPalpha) regulate assembly of the SNARE complex, and alpha-synuclein rescues neurodegeneration due to lack of CSPalpha. We will examine whether virus-mediated over-expression of CSPalpha will restore the deficit in exocytosis in vitro in alpha-synuclein expressing cell lines and in vivo in the human 1-120 truncated alpha-synuclein transgenic mouse line. In particular, we will overexpress CSPalpha in cells over expressing alpha-synuclein and showing a deficit in exocytosis. Furthermore, we will produce viruses expressing the CSPalpha protein that will be injected in the brain of transgenic mice expressing human 1-120 alpha-synuclein to determine whether CSPalpha can also rescue exocytosis in vivo in pre-clinical models.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
Alpha-synuclein is a crucial protein, involved in the development of PD, however its function is not completely understood. Mounting evidence indicates the participation of alpha-synuclein in maintaining normal cell-to-cell communication by ensuring the proper function of synapses, where it participates in vesicle docking and the release of neurotransmitters. Our project will help to clarify whether CSPalpha overexpression could help to restore a normal release of neurotransmitters in a synapse damaged by alpha-synuclein accumulation, providing further insights into the early stages of PD and its possible treatment.
This study will reveal the relevance of alpha-synuclein aggregation at the synapse as a target for PD treatment. If preventing/correcting SNARE redistribution will restore a normal dopamine release, it will indicate a novel direction for therapeutic intervention for PD.