RT-QuIC Using C-Terminally Truncated α-Synuclein Forms Detects Differences in Seeding Propensity of Different Brain Regions from Synucleinopathies

Ilaria Poggiolini,Daniel Erskine,Janarthanan Ponraj,Said Mansour,Nishant N Vaikath,Omar M A El-Agnaf,Christopher M Morris

doi:10.3390/biom11060820

Ilaria Poggiolini, Daniel Erskine + Show 5 more

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https://doi.org/10.3390/biom11060820

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Abstract

Aggregated α-synuclein (αSyn) protein is a core pathological feature of Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). Both PD and DLB demonstrate the presence of diverse intracellular α-synuclein (αSyn) species, including C-terminally truncated αSyn (C-αSyn), although it is unknown how C-αSyn species contribute to disease progression. Using recombinant C-αSyn and PD and DLB brain lysates as seeds in the real-time quaking-induced conversion (RT-QuIC) assay, we explored how C-αSyn may be involved in disease stratification. Comparing the seeding activity of aqueous-soluble fractions to detergent-soluble fractions, and using αSyn 1-130 as substrate for the RT-QuIC assay, the temporal cortex seeds differentiated PD and DLB from healthy controls. In contrast to the temporal cortex, where PD and DLB could not be distinguished, αSyn 1-130 seeded by the detergent-soluble fractions from the PD frontal cortex demonstrated greater seeding efficiency compared to the DLB frontal cortex. Moreover, proteinase K-resistant (PKres) fragments from the RT-QuIC end products using C-αSyn 1-130 or C-αSyn 1-115 were more obvious in the frontal cortex compared to the temporal cortex. Morphological examinations of RT-QuIC end products showed differences in the size of the fibrils between C-αSyn 1-130 and C-αSyn 1-115, in agreement with the RT-QuIC results. These data show that C-αSyn species can distinguish PD from DLB and suggest diversity in αSyn species across these synucleinopathies, which could play a role in disease progression.

Highlights

There isto currently increasing theclinical potential role of distinct species of αSyn contributing the diverse clinical interest featuresin and phenotypes of synucleinopathies, contributing to the diverse clinical features and clinical phenotypes of synucleinopathies, but relatively little is known about whether such species differ in terms of their expression but relatively little is known about whether such differ in terms of of their expression and abundance across different brain regions andspecies between distinct forms synucleinop‐
We report that temporal cortex tissue differentiated cases from controls in RT‐QuIC, no differences in the seed‐propensity of differentiated cases from controls in real-time quaking-induced conversion (RT-QuIC), no differences in the seed-propensity of αSyn were observed across tissue fractions or between Parkinson’s disease (PD) and dementia with Lewy bodies (DLB)
Frontal αSyn were observed across tissue fractions or between PD and DLB

Summary

Introduction

Lewy bodies (LBs) and Lewy neurites (LNs) in subcortical and cortical neurons, while in MSA, αSyn inclusions mainly manifest in glial cells and are referred to as glial cytoplasmic. Biomolecules 2021, 11, 820 inclusions (GCIs) [2,3]. The presence of αSyn aggregates in specific cell types is thought to underlie the phenotypic differences between MSA and the other synucleinopathies. These differences in presentation are potentially due to variable solubilities of αSyn species in specific synucleinopathies and have been proposed to account for the existence of different αSyn strains able to spread from cell to cell in a prion-like manner [4,5,6]. Different synucleinopathies show regional variation in the brain of both the initiation and progression of αSyn pathology, which might in turn affect the intrinsic structure of αSyn aggregates [7,8]

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