IMR Press / FBL / Volume 26 / Issue 11 / DOI: 10.52586/5010
Open Access Article
Seed amplification assays for diagnosing synucleinopathies: the issue of influencing factors
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1 Laboratory of Clinical Neurochemistry, Section of Neurology, Department of Medicine and Surgery, University of Perugia, 06132 Perugia, Italy
2 Section of Physiology and Biochemistry, Department of Medicine and Surgery, University of Perugia, 06132 Perugia, Italy
3 Magnetic Resonance Center (CERM), University of Florence, 50019 Sesto Fiorentino, Italy
4 Department of Chemistry “Ugo Schiff”, University of Florence, 50019 Sesto Fiorentino, Italy
5 Consorzio Interuniversitario Risonanze Magnetiche MetalloProteine (CIRMMP), 50019 Sesto Fiorentino, Italy
Front. Biosci. (Landmark Ed) 2021, 26(11), 1075–1088; https://doi.org/10.52586/5010
Submitted: 6 August 2021 | Revised: 6 October 2021 | Accepted: 26 October 2021 | Published: 30 November 2021
Copyright: © 2021 The Author(s). Published by BRI.
This is an open access article under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/).
Abstract

Background: The prion-like misfolding and aggregation of α-synuclein (α-syn) is involved in the pathophysiology of Parkinson’s disease and other synucleinopathies. Seed amplification assays (SAAs) are biophysical tools that take advantage on the peculiar properties of prion proteins by amplifying small amounts of aggregates in biological fluids at the expense of recombinant monomeric protein added in solution. SAAs have emerged as the most promising tools for the diagnosis of synucleinopathies in vivo. However, the diagnostic outcome of SAAs depends on the aggregation kinetics of α-syn, which in turn is influenced by several experimental variables. Methods: In our work, we analysed the impact on SAAs of some of the most critical experimental factors by considering models that describe the aggregation kinetics of α-syn. Results: We started our analysis by making simulations to understand which kinetic models could explain the aggregation kinetics of α-syn during incubation/shaking cycles. Subsequently, under shaking/incubation cycles similar to the ones commonly used in SAAs, we tested the influence of some analytical variables such as monomer concentration, presence/absence of glass beads, pH, addition of human cerebrospinal fluid, and use of detergents on α-syn aggregation. Conclusions: Our investigation highlighted how optimization and standardization of experimental procedures for α-syn SAAs is of utmost relevance for the ultimate goal of applying these assays in clinical routine. Although these aspects have been evaluated with specific SAA protocols, most of the experimental variables considered influenced very general aggregation mechanisms of α-syn, thus making most of the results obtained from our analyses extendable to other protocols.

Keywords
α-synuclein
PMCA
RT-QuIC
SAAs
Influencing factors
Figures
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