Proteomic analysis of pathological α-synuclein in synucleinopathies in search for new therapeutic and biomarker approaches

This thesis focuses on the proteomic characterization of α-synuclein (α-syn), a central player in the development of synucleinopathies such as multiple system atrophy (MSA). The project explores the hypothesis that post-translational modifications (PTMs) influence α-syn's aggregation and contribute to disease progression. Utilizing mass spectrometry, we examined α-syn extracted from post-mortem brain tissues and from an in vitro mouse model, identifying key PTMs like serine 129 phosphorylation and specific ubiquitination patterns that correlate with pathological aggregation in MSA. The research extends to characterizing C-terminal truncations, highlighting residues like D119 as prevalent truncation sites in MSA samples. These truncations, along with the presence of acetylation and oxidation, indicate a complex interplay of PTMs that may influence α-syn's pathological behavior and highlight their potential as biomarkers. A detailed proteomic analysis of the pathological α-syn protein network in MSA identified numerous proteins within oligodendrocyte cells, and shed light on possibly disrupted cellular pathways, including synaptic vesicle and membrane trafficking, protein degradation systems, and transcriptional regulation, among others.

Efforts in methodological improvements emphasized optimizing α-syn detection through enrichment strategies, such as immunoprecipitation coupled with titanium dioxide (TiO2) enrichment, which yielded greater sensitivity and specificity in detecting α-syn modifications, particularly C-terminal truncation and phosphorylation. Despite these advancements, detecting α-syn in cerebrospinal fluid (CSF) remained challenging, suggesting the need for further development of targeted analytical techniques. Continued research into α-syn PTMs and their biological implications offer significant potential for the discovery of novel therapeutic and diagnostic approaches, ultimately improving clinical interventions and patient outcomes in synucleinopathies.