Quantitative Measurement of the Affinity of Toxic and Nontoxic Misfolded Protein Oligomers for Lipid Bilayers and of its Modulation by Lipid Composition and Trodusquemine

Year: 2021

Authors: Errico S., Ramshini H., Capitini C., Canale C., Spaziano M., Barbut D., Calamai M., Zasloff M., Oropesa-Nusez R., Vendruscolo M., Chiti F.

Autors Affiliation: Univ Florence, Dept Expt & Clin Biomed Sci, Sect Biochem, I-50134 Florence, Italy; Univ Cambridge, Ctr Misfolding Dis, Yusuf Hamied Dept Chem, Cambridge CB2 1EW, England; Payame Noor Univ, Dept Biol, Tehran 193954697, Iran; European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy; Univ Florence, Dept Phys & Astron, I-50019 Sesto Fiorentino, Italy; Univ Genoa, Dept Phys, I-16146 Genoa, Italy; Enterin Inc, Philadelphia, PA 19103 USA; Natl Res Council Italy CNR, Natl Inst Opt, I-50125 Florence, Italy; Georgetown Univ, MedStar Georgetown Transplant Inst, Sch Med, Washington, DC 20007 USA; Uppsala Univ, Dept Mat Sci & Engn, SE-75103 Uppsala, Sweden.

Abstract: Many neurodegenerative diseases are associated with the self-assembly of peptides and proteins into fibrillar aggregates. Soluble misfolded oligomers formed during the aggregation process, or released by mature fibrils, play a relevant role in neurodegenerative processes through their interactions with neuronal membranes. However, the determinants of the cytotoxicity of these oligomers are still unclear. Here we used liposomes and toxic and nontoxic oligomers formed by the same protein to measure quantitatively the affinity of the two oligomeric species for lipid membranes. To this aim, we quantified the perturbation to the lipid membranes caused by the two oligomers by using the fluorescence quenching of two probes embedded in the polar and apolar regions of the lipid membranes and a well-defined protein-oligomer binding assay using fluorescently labeled oligomers to determine the Stern-Volmer and dissociation constants, respectively. With both approaches, we found that the toxic oligomers have a membrane affinity 20-25 times higher than that of nontoxic oligomers. Circular dichroism, intrinsic fluorescence, and FRET indicated that neither oligomer type changes its structure upon membrane interaction. Using liposomes enriched with trodusquemine, a potential small molecule drug known to penetrate lipid membranes and make them refractory to toxic oligomers, we found that the membrane affinity of the oligomers was remarkably lower. At protective concentrations of the small molecule, the binding of the oligomers to the lipid membranes was fully prevented. Furthermore, the affinity of the toxic oligomers for the lipid membranes was found to increase and slightly decrease with GM1 ganglioside and cholesterol content, respectively, indicating that physicochemical properties of lipid membranes modulate their affinity for misfolded oligomeric species.

Journal/Review: ACS CHEMICAL NEUROSCIENCE

Volume: 12 (17)      Pages from: 3189  to: 3202

More Information: This research was funded by the Regione Toscana (FAS-Salute 2018, Project PRAMA), the University of Florence (Fondi di Ateneo), the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 654148 Laserlab-Europe, the MIUR-Italy Progetto Dipartimenti di Eccellenza 2018-2022 allocated to Department of Experimental and Clinical Biomedical Sciences Mario Serio (Florence) and Department of Physics (Genoa).
KeyWords: Alzheimerīs disease; Parkinsonīs disease; protein misfolding neurodegeneration; aminosterols; squalamine; Alzheimerīs disease; Parkinsonīs disease; protein misfolding; neurodegeneration; aminosterols; squalamine
DOI: 10.1021/acschemneuro.1c00327

ImpactFactor: 5.780
Citations: 16
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