Yang, Xue. Investigation of protein - protein interactions underlying alpha-synuclein aggregation in Parkinson's diseases. Retrieved from https://doi.org/doi:10.7282/t3-nqjb-vb61
DescriptionAlpha-synuclein (αSynuclein) accumulation and aggregation is related to many neurodegenerative diseases like Alzheimer's diseases, Parkinson’s diseases, and dementia with Lewy bodies. However, the mechanism of αSynuclein aggregation and the relationship between aggregation pathways and toxicity are still unclear. Beta-synuclein (βSynuclein) is a homologue protein of αSynuclein with high sequence similarity but plays a different role in neurodegenerative diseases. βSynuclein has shown anti-Parkinson capacity in mouse models. In this work, we used βSynuclein as a comparison to answer why αSynuclein fibrils are good templates for seeding aggregation and what kind of interactions promote aggregate formation or inhibition. The work in this thesis explores structure, toxicity, dynamic and seeding aggregation capacity of different αSynuclein oligomers and fibrils which provide critical information for therapeutic targets and designs.
By characterizing and comparing αSynuclein, βSynuclein and α/β co-incubated fibrils, we suggest that the stability and dynamics of the fibrils play an important role in controlling the fibril seeding aggregation ability. However, both αSynuclein and βSynuclein fibrils show similar cellular toxicity which suggest that seeding monomer aggregation is not the only contribution for fibril toxicity. Using solution NMR, we show that the initial step for fibril seeding is through interactions at the first 40 residues of the N-terminus. The interactions between αSynuclein stable oligomers and monomers are primarily located at the first 12 residues which results in inhibiting fibril seeding aggregation processes through competing interactions. Coupling these facts together suggests that peptides or small molecular targets that interact with the N-terminus of αSynuclein may be a good approach to inhibit αSynuclein seeding processes and increase the dynamics of fibril packing interfaces can be novel strategies to reduce amyloid toxicity.