Alpha-Synuclein: Insight into the Hallmark of Parkinson\u27s Disease as a Target for Quantitative Molecular Diagnostics and Therapeutics

Parkinson’s disease (PD) is the second-most common neurodegenerative disease after Alzheimer’s disease. With 500,000 individuals currently living with Parkinson’s and nearly 60,000 new cases diagnosed each year, this disease causes significant financial burden on the healthcare system - amassing to annual expenditures totaling 200 billion dollars; predicted to increase through 2050. The disease phenotype is characterized by a combination of a resting tremor, bradykinesia, muscular rigidity, and depression due to dopaminergic neuronal death in the midbrain. The cause of the neurotoxicity has been largely discussed, with strong evidence suggesting that the protein, alpha-Synuclein, is a key factor. Under native conditions, alpha-Synuclein can be found localized at synaptic terminals where it is hypothesized to be involved in vesicle trafficking and recycling. However, its biochemical profile reveals a hydrophobic region that, once subjected to insult, initiates an aggregation cascade. Oligomeric species—products of the aggregation cascade—demonstrate marked neurotoxicity in dopaminergic neurons and illustrate migratory potential to neighboring healthy neurons, thereby contributing to progressive neurodegeneration. The current golden standard for PD diagnostics is a highly qualitative system involving a process-by-elimination with accuracy that is contingent upon physician experience. This, and a lack of standardized clinical testing procedures, lends to a 25% misdiagnosis rate. Even under circumstances of an accurate PD diagnosis, the only treatment options are pharmacologics that have a wide range of adverse side effects and ultimately contribute to systemic metabolic dysfunction. Thus, the research presented in this thesis seeks to overcome these current challenges by providing (1) a quantitative diagnostic platform and (2) a biomolecular therapeutic, towards oligomeric alpha-Synuclein. Aim 1: serves as a proof-of-concept for the use of catalytic nucleic acid moieties, deoxyribozymes and aptamers, to quantify alpha-Synuclein in a novel manner and explore the ability to detect oligomeric cytotoxic species. The cost-effective nature of these sensors allows for continued optimization. Aim 2: serves to establish a potential therapy that can abrogate alpha-synuclein oligomerization and toxicity through use of a modified Protein Disulfide Isomerase (PDI) peptide when introduced to live cells treated to simulate pre-parkinsonian pathology