4-Oxo-2-nonenal-Induced -Synuclein Oligomers Interact with Membranes in the Cell, Leading to Mitochondrial Fragmentation

Oxidative stress and formation of cytotoxic oligomersby the nativelyunfolded protein & alpha;-synuclein (& alpha;-syn) are both connectedto the development of Parkinson's disease. This effect hasbeen linked to lipid peroxidation and membrane disruption, but thespecific mechanisms behind these phenomena remain unclear. To addressthis, we have prepared & alpha;-syn oligomers (& alpha;SOs) in vitro in the presence of the lipid peroxidation product4-oxo-2-nonenal and investigated their interaction with live cellsusing in-cell NMR as well as stimulated emission depletion (STED)super-resolution and confocal microscopy. We find that the & alpha;SOsinteract strongly with organellar components, leading to strong immobilizationof the protein's otherwise flexible C-terminus. STED microscopyreveals that the oligomers localize to small circular structures insidethe cell, while confocal microscopy shows mitochondrial fragmentationand association with both late endosome and retromer complex beforethe SOs interact with mitochondria. Our study provides direct evidencefor close contact between cytotoxic & alpha;-syn aggregates and membraneouscompartments in the cell.