Drug repurposing screens identifies compounds that inhibit α-synuclein oligomers' membrane disruption and block antibody interactions

Abstract

Small soluble oligomers of the protein -synuclein (SO) have been linked to disruptions in neuronal homeostasis, contributing to the development of Parkinsons Disease (PD). While this makes SO an obvious drug target, the development of effective therapeutics against SO are challenged by its low abundance and structural and morphological complexity. Here we employ two different approaches to neutralize toxic interactions made by SOs with different cellular components. Firstly, we use available data to identify four neuronal proteins as likely candidates for SO interactions, namely Cfl1, Uchl1, Sirt2 and SerRS. However, despite promising results when immobilized, all 4 proteins only bind weakly to SO in solution in microfluidic assays, making them inappropriate for screening. In contrast, the formation of stable contacts formed between SO and vesicles consisting of anionic lipids not only mimics a likely biological role of SO but also provided a platform to screen two small molecule libraries for disruptors of these contacts. Of the 11 leads obtained in this way, 2 significantly impaired SO contacts with other proteins in a sandwich ELISA assay using SO-binding monoclonal antibodies and nanobodies. In addition, 5 of these leads suppressed -synuclein amyloid formation. Thus a repurposing screening that directly targets a key culprit in PD pathogenesis shows therapeutic potential. HighlightsO_LIThe toxic oligomer formed by -synuclein (SO) is an important drug target. C_LIO_LINeuronal proteins found by pull-down assays do not bind SOs in solution. C_LIO_LILiposome assay identifies 7 approved drugs reducing SO membrane disruption. C_LIO_LIWe identify different inhibitory mechanisms used by different compounds. C_LIO_LITwo top drug hits disrupt SO binding to oligomer-specific antibodies. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=123 SRC="FIGDIR/small/511078v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@184611aorg.highwire.dtl.DTLVardef@33049org.highwire.dtl.DTLVardef@1573ae4org.highwire.dtl.DTLVardef@1db6f38_HPS_FORMAT_FIGEXP M_FIG C_FIG