title: Single particle characterization of iron-induced pore-forming alpha-synuclein oligomers.
abstract: Aggregation of alpha-synuclein is a key event in several neurodegenerative diseases, including Parkinson disease. Recent findings suggest that oligomers represent the principal toxic aggregate species. Using confocal single-molecule fluorescence techniques, such as scanning for intensely fluorescent targets (SIFT) and atomic force microscopy, we monitored alpha-synuclein oligomer formation at the single particle level. Organic solvents were used to trigger aggregation, which resulted in small oligomers ("intermediate I"). Under these conditions, Fe(3+) at low micromolar concentrations dramatically increased aggregation and induced formation of larger oligomers ("intermediate II"). Both oligomer species were on-pathway to amyloid fibrils and could seed amyloid formation. Notably, only Fe(3+)-induced oligomers were SDS-resistant and could form ion-permeable pores in a planar lipid bilayer, which were inhibited by the oligomer-specific A11 antibody. Moreover, baicalein and N'-benzylidene-benzohydrazide derivatives inhibited oligomer formation. Baicalein also inhibited alpha-synuclein-dependent toxicity in neuronal cells. Our results may provide a potential disease mechanism regarding the role of ferric iron and of toxic oligomer species in Parkinson diseases. Moreover, scanning for intensely fluorescent targets allows high throughput screening for aggregation inhibitors and may provide new approaches for drug development and therapy.
authors.affiliation: CNS Research, Boehringer Ingelheim Pharma GmbH & Co. KG, CNS Research, Birkendorferstrasse 65, 88397 Biberach, Germany. Marcus.Kostka@boehringer-ingelheim.com
authors.forename: Marcus
authors.initials: M
authors.lastname: Kostka
authors.forename: Tobias
authors.initials: T
authors.lastname: Högen
authors.forename: Karin M
authors.initials: KM
authors.lastname: Danzer
authors.forename: Johannes
authors.initials: J
authors.lastname: Levin
authors.forename: Matthias
authors.initials: M
authors.lastname: Habeck
authors.forename: Andreas
authors.initials: A
authors.lastname: Wirth
authors.forename: Richard
authors.initials: R
authors.lastname: Wagner
authors.forename: Charles G
authors.initials: CG
authors.lastname: Glabe
authors.forename: Sabine
authors.initials: S
authors.lastname: Finger
authors.forename: Udo
authors.initials: U
authors.lastname: Heinzelmann
authors.forename: Patrick
authors.initials: P
authors.lastname: Garidel
authors.forename: Wenzhen
authors.initials: W
authors.lastname: Duan
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Ross
authors.forename: Hans
authors.initials: H
authors.lastname: Kretzschmar
authors.forename: Armin
authors.initials: A
authors.lastname: Giese
mesh_terms: D052160:Benzothiazoles; D004594:Electrophysiology / Q000379:methods; D044950:Flavanones / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D005786:Gene Expression Regulation; D006801:Humans; D007501:Iron / Q000737:chemistry*; D008051:Lipid Bilayers; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008954:Models, Biological; D010300:Parkinson Disease / Q000378:metabolism; D011485:Protein Binding; D012997:Solvents / Q000737:chemistry; D013844:Thiazoles / Q000737:chemistry; D051844:alpha-Synuclein / Q000737:chemistry*
chemical_list: D052160:Benzothiazoles; D044950:Flavanones; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D012997:Solvents; D013844:Thiazoles; D051844:alpha-Synuclein; C009462:thioflavin T; C006680:baicalein; D007501:Iron