Metabolomic study of disease progression in scrapie prion infected mice; validation of a novel method for brain metabolite extraction

Fu, Ze-Lin; Mercier, Pascal; Eskandari-Sedighi, Ghazaleh; Yang, Jing; Westaway, David; Sykes, Brian D.

doi:10.1007/s11306-020-01690-2

Cited by 2 publications

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“…We used a longitudinal experimental design [ 5 , 6 , 26 ], with analyses at sequential 30-day intervals to follow steps in disease pathogenesis. With regard to determining the disease-related endpoint measure of cell loss, we used the isotropic fractionation technique; this is a non-stereological method to quantify different cell populations in the brain based on counting isolated nuclei following detergent lysis of cell membranes and its accuracy has been verified by cross-referencing to other techniques [ 27 – 31 ]; we took advantage of this method to determine the number of cells in the brain at different timepoints in RML inoculated animals, as well as in matched controls.…”

Section: Resultsmentioning

confidence: 99%

Quaternary Structure Changes for PrPSc Predate PrPC Downregulation and Neuronal Death During Progression of Experimental Scrapie Disease

et al. 2020

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Prion diseases are fatal neurodegenerative diseases in mammals with the unique characteristics of misfolding and aggregation of the cellular prion protein (PrPC) to the scrapie prion (PrPSc). Although neuroinflammation and neuronal loss feature within the disease process, the details of PrPC/PrPSc molecular transition to generate different aggregated species, and the correlation between each species and sequence of cellular events in disease pathogenesis are not fully understood. In this study, using mice inoculated with the RML isolate of mouse-adapted scrapie as a model, we applied asymmetric flow field-flow fractionation to monitor PrPC and PrPSc particle sizes and we also measured seeding activity and resistance to proteases. For cellular analysis in brain tissue, we measured inflammatory markers and synaptic damage, and used the isotropic fractionator to measure neuronal loss; these techniques were applied at different timepoints in a cross-sectional study of disease progression. Our analyses align with previous reports defining significant decreases in PrPC levels at pre-clinical stages of the disease and demonstrate that these decreases become significant before neuronal loss. We also identified the earliest PrPSc assemblies at a timepoint equivalent to 40% elapsed time for the disease incubation period; we propose that these assemblies, mostly composed of proteinase K (PK)–sensitive species, play an important role in triggering disease pathogenesis. Lastly, we show that the PK-resistant assemblies of PrPSc that appear at timepoints close to the terminal stage have similar biophysical characteristics, and hence that preparative use of PK-digestion selects for this specific subpopulation. In sum, our data argue that qualitative, as well as quantitative, changes in PrP conformers occur at the midpoint of subclinical phase; these changes affect quaternary structure and may occur at the threshold where adaptive responses become inadequate to deal with pathogenic processes.

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