Early existence and biochemical evolution characterise acutely synaptotoxic PrPSc

Abstract

Although considerable evidence supports that misfolded prion protein (PrP Sc ) is the principal component of “prions”, underpinning both transmissibility and neurotoxicity, clear consensus around a number of fundamental aspects of pathogenesis has not been achieved, including the time of appearance of neurotoxic species during disease evolution. Utilizing a recently reported electrophysiology paradigm, we assessed the acute synaptotoxicity of ex vivo PrP Sc prepared as crude homogenates from brains of M1000 infected wild-type mice (cM1000) harvested at time-points representing 30%, 50%, 70% and 100% of the terminal stage of disease (TSD). Acute synaptotoxicity was assessed by measuring the capacity of cM1000 to impair hippocampal CA1 region long-term potentiation (LTP) and post-tetanic potentiation (PTP) in explant slices. Of particular note, cM1000 from 30% of the TSD was able to cause significant impairment of LTP and PTP, with the induced failure of LTP increasing over subsequent time-points while the capacity of cM1000 to induce PTP failure appeared maximal even at this early stage of disease progression. Evidence that the synaptotoxicity directly related to PrP species was demonstrated by the significant rescue of LTP dysfunction at each time-point through immuno-depletion of >50% of total PrP species from cM1000 preparations. Moreover, similar to our previous observations at the terminal stage of M1000 prion disease, size fractionation chromatography revealed that capacity for acute synpatotoxicity correlated with predominance of oligomeric PrP species in infected brains across all time points, with the profile appearing maximised by 50% of the TSD. Using enhanced sensitivity western blotting, modestly proteinase K (PK)-resistant PrP Sc was detectable at very low levels in cM1000 at 30% of the TSD, becoming robustly detectable by 70% of the TSD at which time substantial levels of highly PK-resistant PrP Sc was also evident. Further illustrating the biochemical evolution of acutely synaptotoxic species the synaptotoxicity of cM1000 from 30%, 50% and 70% of the TSD, but not at 100% TSD, was abolished by digestion of immuno-captured PrP species with mild PK treatment (5μg/ml for an hour at 37°C), demonstrating that the predominant synaptotoxic PrP Sc species up to and including 70% of the TSD were proteinase-sensitive. Overall, these findings in combination with our previous assessments of transmitting prions support that synaptotoxic and infectious M1000 PrP Sc species co-exist from at least 30% of the TSD, simultaneously increasing thereafter, albeit with eventual plateauing of transmitting conformers.

Pathogenic Prion Protein Isoforms Are Not Present in Cerebral Organoids Generated from Asymptomatic Donors Carrying the E200K Mutation Associated with Familial Prion Disease

“…The expression level of PrP is usually significantly increased during the clinical stages of mouse models of acquired prion diseases [ 2 , 13 ]. In transgenic mice expressing chimeric mouse/human PrP with the E200K mutation, the PrP protein level at the end stage of the disease was significantly increased as indicated by the increased PrP immunoreactivity [ 5 ].…”

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

“…As employed here, an in-line DLS detector allows a precise measurement of the size of the eluting particles. The combination of these points makes AF4 particularly useful for studying aggregated PrP species [33,[49][50][51].…”

Handling of endoscopic equipment after use in the case of a patient with suspected prion disease

“…In the prion infection protein the proportion of α-helical structures is smaller than in natural prion proteins, while the proportion of β-folding (β-fold) structures is larger than in natural prion proteins. The erroneous folding of a normal prion protein (PrP C ) into conformers (PrP SC ) with the accumulation of PrP SC in the brain supports the transmission process [18]. The mutated forms of proteins are able to survive in extreme conditions [19].…”

“…Conformation changes the properties of proteins, thus having a direct impact on the principles of tool reprocessing (Table 1) [23]. [18,24,25]. Major animal diseases include scrapie of sheep and goats, bovine spongiform encephalopathy, chronic debilitating disease of cervids and camel prion disease (identified in 2018) [25].…”

“…Major animal diseases include scrapie of sheep and goats, bovine spongiform encephalopathy, chronic debilitating disease of cervids and camel prion disease (identified in 2018) [25]. The debilitating disease of cervids has spread in North America and has recently appeared in Norway and Finland [18,26]. All diseases caused by prions, referred to as transmissible spongiform encephalopathies, are lethal.…”