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3554 KiB

Open AccessArticle

Assessing Proteinase K Resistance of Fish Prion Proteins in a Scrapie-Infected Mouse Neuroblastoma Cell Line

by Evgenia Salta, Eirini Kanata, Christos A. Ouzounis, Sabine Gilch, Hermann Schätzl and Theodoros Sklaviadis

Viruses 2014, 6(11), 4398-4421; https://doi.org/10.3390/v6114398 - 13 Nov 2014

Cited by 5 | Viewed by 7372

Abstract

The key event in prion pathogenesis is the structural conversion of the normal cellular protein, PrP^C, into an aberrant and partially proteinase K resistant isoform, PrP^Sc. Since the minimum requirement for a prion disease phenotype is the expression of [...] Read more.

The key event in prion pathogenesis is the structural conversion of the normal cellular protein, PrP^C, into an aberrant and partially proteinase K resistant isoform, PrP^Sc. Since the minimum requirement for a prion disease phenotype is the expression of endogenous PrP in the host, species carrying orthologue prion genes, such as fish, could in theory support prion pathogenesis. Our previous work has demonstrated the development of abnormal protein deposition in sea bream brain, following oral challenge of the fish with natural prion infectious material. In this study, we used a prion-infected mouse neuroblastoma cell line for the expression of three different mature fish PrP proteins and the evaluation of the resistance of the exogenously expressed proteins to proteinase K treatment (PK), as an indicator of a possible prion conversion. No evidence of resistance to PK was detected for any of the studied recombinant proteins. Although not indicative of an absolute inability of the fish PrPs to structurally convert to pathogenic isoforms, the absence of PK-resistance may be due to supramolecular and conformational differences between the mammalian and piscine PrPs. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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313 KiB

Open AccessArticle

Molecular Modeling of Prion Transmission to Humans

by Etienne Levavasseur, Nicolas Privat, Juan-Carlos Espinosa Martin, Steve Simoneau, Thierry Baron, Benoit Flan, Juan-Maria Torres and Stéphane Haïk

Viruses 2014, 6(10), 3766-3777; https://doi.org/10.3390/v6103766 - 2 Oct 2014

Cited by 12 | Viewed by 7534

Abstract

Using different prion strains, such as the variant Creutzfeldt-Jakob disease agent and the atypical bovine spongiform encephalopathy agents, and using transgenic mice expressing human or bovine prion protein, we assessed the reliability of protein misfolding cyclic amplification (PMCA) to model interspecies and genetic [...] Read more.

Using different prion strains, such as the variant Creutzfeldt-Jakob disease agent and the atypical bovine spongiform encephalopathy agents, and using transgenic mice expressing human or bovine prion protein, we assessed the reliability of protein misfolding cyclic amplification (PMCA) to model interspecies and genetic barriers to prion transmission. We compared our PMCA results with in vivo transmission data characterized by attack rates, i.e., the percentage of inoculated mice that developed the disease. Using 19 seed/substrate combinations, we observed that a significant PMCA amplification was only obtained when the mouse line used as substrate is susceptible to the corresponding strain. Our results suggest that PMCA provides a useful tool to study genetic barriers to transmission and to study the zoonotic potential of emerging prion strains. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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333 KiB

Open AccessCommunication

Low Copper and High Manganese Levels in Prion Protein Plaques

by Christopher J. Johnson, P.U.P.A. Gilbert, Mike Abrecht, Katherine L. Baldwin, Robin E. Russell, Joel A. Pedersen, Judd M. Aiken and Debbie McKenzie

Viruses 2013, 5(2), 654-662; https://doi.org/10.3390/v5020654 - 11 Feb 2013

Cited by 24 | Viewed by 7014

Abstract

Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal [...] Read more.

Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of copper and increased levels of manganese are associated with disease. The objectives of this study were to: (1) assess copper and manganese levels in healthy and TSE-infected Syrian hamster brain homogenates; (2) determine if the distribution of these metals can be mapped in TSE-infected brain tissue using X-ray photoelectron emission microscopy (X-PEEM) with synchrotron radiation; and (3) use X-PEEM to assess the relative amounts of copper and manganese in prion plaques in situ. In agreement with studies of other TSEs and species, we found reduced brain levels of copper and increased levels of manganese associated with disease in our hamster model. We also found that the in situ levels of these metals in brainstem were sufficient to image by X-PEEM. Using immunolabeled prion plaques in directly adjacent tissue sections to identify regions to image by X-PEEM, we found a statistically significant relationship of copper-manganese dysregulation in prion plaques: copper was depleted whereas manganese was enriched. These data provide evidence for prion plaques altering local transition metal distribution in the TSE-infected central nervous system. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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Review

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1226 KiB

Open AccessReview

The Standard Scrapie Cell Assay: Development, Utility and Prospects

by Jacques Van der Merwe, Judd Aiken, David Westaway and Debbie McKenzie

Viruses 2015, 7(1), 180-198; https://doi.org/10.3390/v7010180 - 16 Jan 2015

Cited by 11 | Viewed by 9288

Abstract

Prion diseases are a family of fatal neurodegenerative diseases that involve the misfolding of a host protein, PrP^C. Measuring prion infectivity is necessary for determining efficacy of a treatment or infectivity of a prion purification procedure; animal bioassays are, however, very [...] Read more.

Prion diseases are a family of fatal neurodegenerative diseases that involve the misfolding of a host protein, PrP^C. Measuring prion infectivity is necessary for determining efficacy of a treatment or infectivity of a prion purification procedure; animal bioassays are, however, very expensive and time consuming. The Standard Scrapie Cell Assay (SSCA) provides an alternative approach. The SSCA facilitates quantitative in vitro analysis of prion strains, titres and biological properties. Given its robust nature and potential for high throughput, the SSCA has substantial utility for in vitro characterization of prions and can be deployed in a number of settings. Here we provide an overview on establishing the SSCA, its use in studies of disease dissemination and pathogenesis, potential pitfalls and a number of remaining challenges. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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1067 KiB

Open AccessReview

Protein Folding Activity of the Ribosome (PFAR) –– A Target for Antiprion Compounds

by Debapriya Banerjee and Suparna Sanyal

Viruses 2014, 6(10), 3907-3924; https://doi.org/10.3390/v6103907 - 23 Oct 2014

Cited by 22 | Viewed by 8596

Abstract

Prion diseases are fatal neurodegenerative diseases affecting mammals. Prions are misfolded amyloid aggregates of the prion protein (PrP), which form when the alpha helical, soluble form of PrP converts to an aggregation-prone, beta sheet form. Thus, prions originate as protein folding problems. The [...] Read more.

Prion diseases are fatal neurodegenerative diseases affecting mammals. Prions are misfolded amyloid aggregates of the prion protein (PrP), which form when the alpha helical, soluble form of PrP converts to an aggregation-prone, beta sheet form. Thus, prions originate as protein folding problems. The discovery of yeast prion(s) and the development of a red-/white-colony based assay facilitated safe and high-throughput screening of antiprion compounds. With this assay three antiprion compounds; 6-aminophenanthridine (6AP), guanabenz acetate (GA), and imiquimod (IQ) have been identified. Biochemical and genetic studies reveal that these compounds target ribosomal RNA (rRNA) and inhibit specifically the protein folding activity of the ribosome (PFAR). The domain V of the 23S/25S/28S rRNA of the large ribosomal subunit constitutes the active site for PFAR. 6AP and GA inhibit PFAR by competition with the protein substrates for the common binding sites on the domain V rRNA. PFAR inhibition by these antiprion compounds opens up new possibilities for understanding prion formation, propagation and the role of the ribosome therein. In this review, we summarize and analyze the correlation between PFAR and prion processes using the antiprion compounds as tools. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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606 KiB

Open AccessReview

The Structure of Human Prions: From Biology to Structural Models—Considerations and Pitfalls

by Claudia Y. Acevedo-Morantes and Holger Wille

Viruses 2014, 6(10), 3875-3892; https://doi.org/10.3390/v6103875 - 20 Oct 2014

Cited by 39 | Viewed by 14130

Abstract

The Structure of Human Prions: From Biology to Structural Models — Considerations and Pitfalls Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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641 KiB

Open AccessReview

Prion Protein-Specific Antibodies-Development, Modes of Action and Therapeutics Application

by Tihana Lenac Rovis and Giuseppe Legname

Viruses 2014, 6(10), 3719-3737; https://doi.org/10.3390/v6103719 - 1 Oct 2014

Cited by 13 | Viewed by 9963

Abstract

Prion diseases or Transmissible Spongiform Encephalopathies (TSEs) are lethal neurodegenerative disorders involving the misfolding of the host encoded cellular prion protein, PrP^C. This physiological form of the protein is expressed throughout the body, and it reaches the highest levels in the [...] Read more.

Prion diseases or Transmissible Spongiform Encephalopathies (TSEs) are lethal neurodegenerative disorders involving the misfolding of the host encoded cellular prion protein, PrP^C. This physiological form of the protein is expressed throughout the body, and it reaches the highest levels in the central nervous system where the pathology occurs. The conversion into the pathogenic isoform denoted as prion or PrP^Sc is the key event in prion disorders. Prominent candidates for the treatment of prion diseases are antibodies and their derivatives. Anti-PrP^C antibodies are able to clear PrP^Sc from cell culture of infected cells. Furthermore, application of anti-PrP^C antibodies suppresses prion replication in experimental animal models. Major drawbacks of immunotherapy are immune tolerance, the risks of neurotoxic side effects, limited ability of compounds to cross the blood-brain barrier and their unfavorable pharmacokinetic. The focus of this review is to recapitulate the current understanding of the molecular mechanisms for antibody mediated anti-prion activity. Although relevant for designing immunotherapeutic tools, the characterization of key antibody parameters shaping the molecular mechanism of the PrP^C to PrP^Sc conversion remains elusive. Moreover, this review illustrates the various attempts towards the development of anti-PrP antibody compounds and discusses therapeutic candidates that modulate PrP expression. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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753 KiB

Open AccessReview

Cellular Aspects of Prion Replication In Vitro

by Andrea Grassmann, Hanna Wolf, Julia Hofmann, James Graham and Ina Vorberg

Viruses 2013, 5(1), 374-405; https://doi.org/10.3390/v5010374 - 22 Jan 2013

Cited by 50 | Viewed by 12634

Abstract

Prion diseases or transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative disorders in mammals that are caused by unconventional agents predominantly composed of aggregated misfolded prion protein (PrP). Prions self-propagate by recruitment of host-encoded PrP into highly ordered b-sheet rich aggregates. Prion strains [...] Read more.

Prion diseases or transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative disorders in mammals that are caused by unconventional agents predominantly composed of aggregated misfolded prion protein (PrP). Prions self-propagate by recruitment of host-encoded PrP into highly ordered b-sheet rich aggregates. Prion strains differ in their clinical, pathological and biochemical characteristics and are likely to be the consequence of distinct abnormal prion protein conformers that stably replicate their alternate states in the host cell. Understanding prion cell biology is fundamental for identifying potential drug targets for disease intervention. The development of permissive cell culture models has greatly enhanced our knowledge on entry, propagation and dissemination of TSE agents. However, despite extensive research, the precise mechanism of prion infection and potential strain effects remain enigmatic. This review summarizes our current knowledge of the cell biology and propagation of prions derived from cell culture experiments. We discuss recent findings on the trafficking of cellular and pathologic PrP, the potential sites of abnormal prion protein synthesis and potential co-factors involved in prion entry and propagation. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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1439 KiB

Open AccessReview

Prion Disease and the Innate Immune System

by Barry M. Bradford and Neil A. Mabbott

Viruses 2012, 4(12), 3389-3419; https://doi.org/10.3390/v4123389 - 28 Nov 2012

Cited by 38 | Viewed by 13720

Abstract

Prion diseases or transmissible spongiform encephalopathies are a unique category of infectious protein-misfolding neurodegenerative disorders. Hypothesized to be caused by misfolding of the cellular prion protein these disorders possess an infectious quality that thrives in immune-competent hosts. While much has been discovered about [...] Read more.

Prion diseases or transmissible spongiform encephalopathies are a unique category of infectious protein-misfolding neurodegenerative disorders. Hypothesized to be caused by misfolding of the cellular prion protein these disorders possess an infectious quality that thrives in immune-competent hosts. While much has been discovered about the routing and critical components involved in the peripheral pathogenesis of these agents there are still many aspects to be discovered. Research into this area has been extensive as it represents a major target for therapeutic intervention within this group of diseases. The main focus of pathological damage in these diseases occurs within the central nervous system. Cells of the innate immune system have been proven to be critical players in the initial pathogenesis of prion disease, and may have a role in the pathological progression of disease. Understanding how prions interact with the host innate immune system may provide us with natural pathways and mechanisms to combat these diseases prior to their neuroinvasive stage. We present here a review of the current knowledge regarding the role of the innate immune system in prion pathogenesis. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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745 KiB

Open AccessReview

Cellular Prion Protein: From Physiology to Pathology

by Sei-ichi Yusa, José B. Oliveira-Martins, Yoshiko Sugita-Konishi and Yutaka Kikuchi

Viruses 2012, 4(11), 3109-3131; https://doi.org/10.3390/v4113109 - 14 Nov 2012

Cited by 30 | Viewed by 25445

Abstract

The human cellular prion protein (PrP^C) is a glycosylphosphatidylinositol (GPI) anchored membrane glycoprotein with two N-glycosylation sites at residues 181 and 197. This protein migrates in several bands by Western blot analysis (WB). Interestingly, PNGase F treatment of human brain homogenates [...] Read more.

The human cellular prion protein (PrP^C) is a glycosylphosphatidylinositol (GPI) anchored membrane glycoprotein with two N-glycosylation sites at residues 181 and 197. This protein migrates in several bands by Western blot analysis (WB). Interestingly, PNGase F treatment of human brain homogenates prior to the WB, which is known to remove the N-glycosylations, unexpectedly gives rise to two dominant bands, which are now known as C-terminal (C1) and N-terminal (N1) fragments. This resembles the β-amyloid precursor protein (APP) in Alzheimer disease (AD), which can be physiologically processed by α-, β-, and γ-secretases. The processing of APP has been extensively studied, while the identity of the cellular proteases involved in the proteolysis of PrP^C and their possible role in prion biology has remained limited and controversial. Nevertheless, there is a strong correlation between the neurotoxicity caused by prion proteins and the blockade of their normal proteolysis. For example, expression of non-cleavable PrP^C mutants in transgenic mice generates neurotoxicity, even in the absence of infectious prions, suggesting that PrP^C proteolysis is physiologically and pathologically important. As many mouse models of prion diseases have recently been developed and the knowledge about the proteases responsible for the PrP^C proteolysis is accumulating, we examine the historical experimental evidence and highlight recent studies that shed new light on this issue. Full article

(This article belongs to the Special Issue Recent Developments in the Prion Field)

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