BackgroundThe accumulation of protease resistant conformers of the prion protein (PrPres) is a key pathological feature of prion diseases. Polyanions, including RNA and glycosaminoglycans have been identified as factors that contribute to the propagation, transmission and pathogenesis of prion disease. Recent studies have suggested that the contribution of these cofactors to prion propagation may be species specific.Methodology/Principal FindingIn this study a cell-free assay was used to investigate the molecular basis of polyanion stimulated PrPres formation using brain tissue or cell line derived murine PrP. Enzymatic depletion of endogenous nucleic acids or heparan sulphate (HS) from the PrPC substrate was found to specifically prevent PrPres formation seeded by mouse derived PrPSc. Modification of the negative charge afforded by the sulphation of glycosaminoglycans increased the ability of a familial PrP mutant to act as a substrate for PrPres formation, while having no effect on PrPres formed by wildtype PrP. This difference may be due to the observed differences in the binding of wild type and mutant PrP for glycosaminoglycans.Conclusions/SignificanceCofactor requirements for PrPres formation are host species and prion strain specific and affected by disease associated mutations of the prion protein. This may explain both species and strain dependent propagation characteristics and provide insights into the underlying mechanisms of familial prion disease. It further highlights the challenge of designing effective therapeutics against a disease which effects a range of mammalian species, caused by range of aetiologies and prion strains.
Prion diseases or transmissible spongiform encephalopathies are a group of fatal and transmissible disorders affecting the central nervous system of humans and animals. The principal agent of prion disease transmission and pathogenesis is proposed to be an abnormal protease-resistant isoform of the normal cellular prion protein. The microtubule-associated protein tau is elevated in patients with Creutzfeldt-Jakob disease. To determine whether tau expression contributes to prion disease pathogenesis, tau knockout and control wild-type mice were infected with the M1000 strain of mouse-adapted human prions. Immunohistochemical analysis for total tau expression in prion-infected wild-type mice indicated tau aggregation in the cytoplasm of a subpopulation of neurons in regions associated with spongiform change. Western immunoblot analysis of brain homogenates revealed a decrease in total tau immunoreactivity and epitope-specific changes in tau phosphorylation. No significant difference in incubation period or other disease features were observed between tau knockout and wild-type mice with clinical prion disease. These results demonstrate that, in this model of prion disease, tau does not contribute to the pathogenesis of prion disease and that changes in the tau protein profile observed in mice with clinical prion disease occurs as a consequence of the prion-induced pathogenesis.
This study aimed to explore the quality of life (QoL) of adult patients with epilepsy (PwE) in Australia and its relationship with comorbidities and adverse events (AEs) from antiepileptic drugs (AEDs). Methods: Cross-sectional surveys were completed by PwE, or carer proxies, recruited via the online pharmacy application MedAdvisor and Australian PwE Facebook groups from May to August 2018. Data were collected on demographics, epilepsy severity and management, AEs, comorbidities, and QoL (using the Patient-Weighted Quality of Life in Epilepsy Inventory [QOLIE-10-P] total score). Two linear regression models were constructed to explore associations between AEs or comorbidities and QOLIE-10-P score, with possible confounders determined using stepwise selection. Results: Nine hundred and seventy-eight of 1267 responses were eligible (mean age of respondents: 44.5 years, 64% female, 52% employed). Recent AED use was reported by 97%; 47% were on AED monotherapy, 35% had ≤2 lifetime AEDs, and 55% were seizure-free for N 1 year. After stepwise selection, control variables included in both models were time since diagnosis, employment status, seizure frequency, number of currently prescribed AEDs, and number of general practitioner (GP) visits per year. In the model for comorbidities, "psychiatric disorders" was associated with the largest QOLIE-10-P score decrease (−23.14, p b 0.001). In the model for AEs, which additionally controlled for depression and anxiety disorder, self-reported "memory problems" was associated with the largest decrease in QOLIE-10-P score (−14.27, p b 0.001). Conclusions: In this survey of Australian PwE, many of whom had relatively well-controlled epilepsy, psychiatric and self-reported memory problems were common and associated with the greatest detrimental impact on QoL. Further research is needed to better understand the underlying causes of impaired QoL and thereby improve its management.
Background: Sporadic Creutzfeldt-Jakob disease (CJD) encompasses a spectrum of clinical phenotypes, the origin of which has not been fully elucidated. Results: Cell-free prion protein misfolding by sporadic CJD subtypes was affected by brain tissue composition and not related to absolute levels of PrP C . Conclusion: Tissue environment contributes to CJD subtype-specific prion protein misfolding. Significance: Non-PrP C cofactors may contribute to the development of sporadic CJD.
Prion diseases are a group of invariably fatal and transmissible neurodegenerative disorders that are associated with the misfolding of the normal cellular prion protein, with the misfolded conformers constituting an infectious unit referred to as a "prion". Prions can spread within an affected organism by directly propagating this misfolding within and between cells and can transmit disease between animals of the same and different species. Prion diseases have a range of clinical phenotypes in humans and animals, with a principle determinant of this attributed to different conformations of the misfolded protein, referred to as prion strains. This chapter will describe the different clinical manifestations of prion diseases, the evidence that these diseases can be transmitted by an infectious protein and how the misfolding of this protein causes disease.
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