Seeding and structural varibility in α-synucleinopathies

Abstract

In the present work, we were interested in applying the Real-time quaking-induced conversion (RT-QuIC) for the detection of the seeding activity of Dementia with Lewy bodies (DLB) and Parkinson’s disease (PD) brain derived α-synuclein seeds. and analyzing the structure and morphology of the α-synuclein aggregates generated via RTQuIC. A different seeding and conversion ability support the existence of α-synuclein conformational variants in both α-synucleinopathies. To this aim, brain materials derived from neuropathologically well-characterised cases with DLB, PD and controls have been processed by filtration and centrifugation steps to obtain an α-synuclein seeding competent fraction, deployed as seed for the RT-QuIC. Biochemical and morphological analyses of RT-QuIC products were conducted by western blot, dot blot analysis, Raman spectroscopy, atomic force microscopy and transmission electron microscopy analyses. We observed a different seeding activity between DLB and PD, which resulted in the generation of a PK-resistant and fibrillary α- synuclein species in DLB seeded reactions, while PD and control seeds failed in the conversion of wild type α-synuclein substrate. The structural variance between DLB and PD seeding kinetics and products indicated the existence of different α-synuclein stains in these groups. Our study contributes to the understanding of the clinical heterogeneity observed among α-synucleinoèpathies and opens news avenues for the future development of strain-specific therapies. !