After oral exposure, prions are thought to enter Peyer's patches via M cells and accumulate first upon follicular dendritic cells (FDCs) before spreading to the nervous system. How prions are ...actually initially acquired from the gut lumen is not known. Using high-resolution immunofluorescence and cryo-immunogold electron microscopy, we report the trafficking of the prion protein (PrP) toward Peyer's patches of wild-type and PrP-deficient mice. PrP was transiently detectable at 1 day post feeding (dpf) within large multivesicular LAMP1-positive endosomes of enterocytes in the follicle-associated epithelium (FAE) and at much lower levels within M cells. Subsequently, PrP was detected on vesicles in the late endosomal compartments of macrophages in the subepithelial dome. At 7-21 dpf, increased PrP labelling was observed on the plasma membranes of FDCs in germinal centres of Peyer's patches from wild-type mice only, identifying FDCs as the first sites of PrP conversion and replication. Detection of PrP on extracellular vesicles displaying FAE enterocyte-derived A33 protein implied transport towards FDCs in association with FAE-derived vesicles. By 21 dpf, PrP was observed on the plasma membranes of neurons within neighbouring myenteric plexi. Together, these data identify a novel potential M cell-independent mechanism for prion transport, mediated by FAE enterocytes, which acts to initiate conversion and replication upon FDCs and subsequent infection of enteric nerves.
The cerebrospinal fluid (CSF) real-time quaking-induced conversion assay (RT-QuIC) is an ultrasensitive prion amyloid seeding assay for diagnosis of sporadic Creutzfeldt-Jakob disease (CJD) but ...several prion strains remain unexplored or resistant to conversion with commonly used recombinant prion protein (rPrP) substrates. Here, bank vole (BV) rPrP was used to study seeding by a wide range of archived post-mortem human CSF samples from cases of sporadic, acquired and various inherited prion diseases in high throughput 384-well format. BV rPrP substrate yielded positive reactions in 70/79 cases of sporadic CJD Sensitivity 88.6% (95% CI 79.5-94.7%), 1/2 variant CJD samples, and 9/20 samples from various inherited prion diseases; 5/57 non-prion disease control CSFs had positive reactions, yielding an overall specificity of 91.2% (95% CI 80.1-97.1%). Despite limitations of using post-mortem samples and our results' discrepancy with other studies, we demonstrated for the first time that BV rPrP is susceptible to conversion by human CSF samples containing certain prion strains not previously responsive in conventional rPrPs, thus justifying further optimisation for wider diagnostic and prognostic use.
The most common neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease, are characterized by the misfolding of a small number of proteins that assemble into ordered ...aggregates in affected brain cells. For many years, the events leading to aggregate formation were believed to be entirely cell-autonomous, with protein misfolding occurring independently in many cells. Recent research has now shown that cell non-autonomous mechanisms are also important for the pathogenesis of neurodegenerative diseases with intracellular filamentous inclusions. The intercellular transfer of inclusions made of tau, α-synuclein, huntingtin and superoxide dismutase 1 has been demonstrated, revealing the existence of mechanisms reminiscent of those by which prions spread through the nervous system.
Highly infectious prions are not directly neurotoxic Benilova, Iryna; Reilly, Madeleine; Terry, Cassandra ...
Proceedings of the National Academy of Sciences - PNAS,
09/2020, Letnik:
117, Številka:
38
Journal Article
Recenzirano
Odprti dostop
Prions are infectious agents which cause rapidly lethal neurodegenerative diseases in humans and animals following long, clinically silent incubation periods. They are composed of multichain ...assemblies of misfolded cellular prion protein. While it has long been assumed that prions are themselves neurotoxic, recent development of methods to obtain exceptionally pure prions from mouse brain with maintained strain characteristics, and in which defined structures—paired rod-like double helical fibers—can be definitively correlated with infectivity, allowed a direct test of this assertion. Here we report that while brain homogenates from symptomatic prion-infected mice are highly toxic to cultured neurons, exceptionally pure intact high-titer infectious prions are not directly neurotoxic. We further show that treatment of brain homogenates from prion-infected mice with sodium lauroylsarcosine destroys toxicity without diminishing infectivity. This is consistent with models in which prion propagation and toxicity can be mechanistically uncoupled.
The prion's elusive reason for being Aguzzi, Adriano; Baumann, Frank; Bremer, Juliane
Annual review of neuroscience,
01/2008, Letnik:
31
Journal Article
Recenzirano
The protein-only hypothesis posits that the infectious agent causing transmissible spongiform encephalopathies consists of protein and lacks any informational nucleic acids. This agent, termed prion ...by Stanley Prusiner, is thought to consist partly of PrP(Sc), a conformational isoform of a normal cellular protein termed PrP(C). Scientists and lay persons have been fascinated by the prion concept, and it has been subjected to passionate critique and intense experimental scrutiny. As a result, PrP(C) and its isoforms rank among the most intensively studied proteins encoded by the mammalian genome. Despite all this research, both the physiological function of PrP(C) and the molecular pathways leading to neurodegeneration in prion disease remain unknown. Here we review the salient traits of those diseases ascribed to improper behavior of the prion protein and highlight how the physiological functions of PrP(C) may help explain the toxic phenotypes observed in prion disease.
Prion science has been on a rollercoaster for two decades. In the mid 1990s, the specter of mad cow disease (bovine spongiform encephalopathy, BSE) provoked an unprecedented public scare that was ...first precipitated by the realization that this animal prion disease could be transmitted to humans and then rekindled by the evidence that BSE-infected humans could pass on the infection through blood transfusions. Along with the gradual disappearance of BSE, the interest in prions has waned with the general public, funding agencies and prospective PhD students. In the past few years, however, a bewildering variety of diseases have been found to share features with prion infections, including cell-to-cell transmission. Here we review these developments and summarize those open questions that we currently deem most interesting in prion biology: how do prions damage their hosts, and how do hosts attempt to neutralize invading prions?
Prions are lethal mammalian pathogens composed of aggregated conformational isomers of a host-encoded glycoprotein and which appear to lack nucleic acids. Their unique biology, allied with the ...public-health risks posed by prion zoonoses such as bovine spongiform encephalopathy, has focused much attention on the molecular basis of prion propagation and the "species barrier" that controls cross-species transmission. Both are intimately linked to understanding how multiple prion "strains" are encoded by a protein-only agent. The underlying mechanisms are clearly of much wider importance, and analogous protein-based inheritance mechanisms are recognized in yeast and fungi. Recent advances suggest that prions themselves are not directly neurotoxic, but rather their propagation involves production of toxic species, which may be uncoupled from infectivity.
Prions are proteinaceous infectious particles that replicate by structural conversion of the host-encoded cellular prion protein (PrP
), causing fatal neurodegenerative diseases in mammals. ...Species-specific amino acid substitutions (AAS) arising from single nucleotide polymorphisms within the prion protein gene (
) modulate prion disease pathogenesis, and, in several instances, reduce susceptibility of homo- or heterozygous AAS carriers to prion infection. However, a mechanistic understanding of their protective effects against clinical disease is missing. We generated gene-targeted mouse infection models of chronic wasting disease (CWD), a highly contagious prion disease of cervids. These mice express wild-type deer or PrP
harboring the S138N substitution homo- or heterozygously, a polymorphism found exclusively in reindeer (
) and fallow deer (
). The wild-type deer PrP-expressing model recapitulated CWD pathogenesis including fecal shedding. Encoding at least one 138N allele prevented clinical CWD, accumulation of protease-resistant PrP (PrP
) and abnormal PrP deposits in the brain tissue. However, prion seeding activity was detected in spleens, brains, and feces of these mice, suggesting subclinical infection accompanied by prion shedding. 138N-PrP
was less efficiently converted to PrP
in vitro than wild-type deer (138SS) PrP
. Heterozygous coexpression of wild-type deer and 138N-PrP
resulted in dominant-negative inhibition and progressively diminished prion conversion over serial rounds of protein misfolding cyclic amplification. Our study indicates that heterozygosity at a polymorphic
codon can confer the highest protection against clinical CWD and highlights the potential role of subclinical carriers in CWD transmission.
Mechanisms of prion-induced toxicity Mercer, Robert C. C.; Harris, David A.
Cell and tissue research,
04/2023, Letnik:
392, Številka:
1
Journal Article
Recenzirano
Prion diseases are devastating neurodegenerative diseases caused by the structural conversion of the normally benign prion protein (PrP
C
) to an infectious, disease-associated, conformer, PrP
Sc
. ...After decades of intense research, much is known about the self-templated prion conversion process, a phenomenon which is now understood to be operative in other more common neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. In this review, we provide the current state of knowledge concerning a relatively poorly understood aspect of prion diseases: mechanisms of neurotoxicity. We provide an overview of proposed functions of PrP
C
and its interactions with other extracellular proteins in the central nervous system, in vivo and in vitro models used to delineate signaling events downstream of prion propagation, the application of omics technologies, and the emerging appreciation of the role played by non-neuronal cell types in pathogenesis.
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