Ezrin is a Potent Modulator of Alpha-Synuclein Oligomerization

Abstract

Alpha-synuclein oligomers are associated with toxicity in Parkinson's disease. Different forms of alpha-synuclein (aS) have been described, some of which can destabilize lipid bilayers, and seed the formation of fibrillar assemblies. Therapeutic interventions such as molecular chaperones and small molecule inhibitors are sought to depopulate these transient intermediates and thus diminish their toxicity.We have identified ezrin, a microtubule-associated protein that belongs to the ezrin radixin moesin family, as a potent inhibitor of aS aggregation at sub-stoichiometric concentrations. Evidence showed that binding of ezrin to aS causes conformational rearrangements and sequesters the protein in amorphous aggregates thus preventing fibril formation and rescuing toxicity in primary neurons and yeast cells, thereby acting as a non-conventional chaperone.We have produced and characterized alternate aS oligomers by size exclusion chromatography, circular dichroism, TEM, dot blotting and ThT fluorescence. One group of oligomers is associated with a higher β-sheet content and can be internalized in human neuronal model cells. Following treatment with these oligomers prepared with incorporation of fluorescently labeled aS, we observed their uptake into human SH-EP cells. The other group of oligomers is A11 antibody reactive, mainly unstructured and result in significant cell death.We hypothesize that binding of ezrin may alter the biophysical, biological characteristics and aggregation properties of aS oligomers. Current efforts are concentrating on investigating the interaction of ezrin with these alternate oligomeric species.