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Epitope scanning indicates structural differences in brain-derived monomeric and aggregated mutant prion proteins related to genetic prion diseases. Biochem J 2013; 454:417-25. [PMID: 23808898 DOI: 10.1042/bj20130563] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Genetic Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia and prion protein cerebral amyloid angiopathy are clinically and neuropathologically distinct neurodegenerative diseases linked to mutations in the PRNP gene encoding the cellular prion protein (PrPC). How sequence variants of PRNP encode the information to specify these disease phenotypes is not known. It is suggested that each mutation produces a misfolded variant of PrPC with specific neurotoxic properties. However, structural studies of recombinant PrP did not detect major differences between wild-type and mutant molecules, pointing to the importance of investigating mutant PrPs from mammalian brains. We used surface plasmon resonance and a slot-blot immunoassay to analyse the antibody-binding profiles of soluble and insoluble PrP molecules extracted from the brains of transgenic mice modelling different prion diseases. By measuring the reactivity of monoclonal antibodies against different PrP epitopes, we obtained evidence of conformational differences between wild-type and mutant PrPs, and among different mutants. We detected structural heterogeneity in both monomeric and aggregated PrP, supporting the hypothesis that the phenotype of genetic prion diseases is encoded by mutant PrP conformation and assembly state.
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52
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Huang VJ, Stein KC, True HL. Spontaneous variants of the [RNQ+] prion in yeast demonstrate the extensive conformational diversity possible with prion proteins. PLoS One 2013; 8:e79582. [PMID: 24205387 PMCID: PMC3808357 DOI: 10.1371/journal.pone.0079582] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/02/2013] [Indexed: 11/26/2022] Open
Abstract
Prion strains (or variants) are structurally distinct amyloid conformations arising from a single polypeptide sequence. The existence of prion strains has been well documented in mammalian prion diseases. In many cases, prion strains manifest as variation in disease progression and pathology, and in some cases, these prion strains also show distinct biochemical properties. Yet, the underlying basis of prion propagation and the extent of conformational possibilities available to amyloidogenic proteins remain largely undefined. Prion proteins in yeast that are also capable of maintaining multiple self-propagating structures have provided much insight into prion biology. Here, we explore the vast structural diversity of the yeast prion [RNQ+] in Saccharomyces cerevisiae. We screened for the formation of [RNQ+] in vivo, allowing us to calculate the rate of spontaneous formation as ~2.96x10-6, and successfully isolate several different [RNQ+] variants. Through a comprehensive set of biochemical and biological analyses, we show that these prion variants are indeed novel. No individual property or set of properties, including aggregate stability and size, was sufficient to explain the physical basis and range of prion variants and their resulting cellular phenotypes. Furthermore, all of the [RNQ+] variants that we isolated were able to facilitate the de novo formation of the yeast prion [PSI+], an epigenetic determinant of translation termination. This supports the hypothesis that [RNQ+] acts as a functional amyloid in regulating the formation of [PSI+] to produce phenotypic diversity within a yeast population and promote adaptation. Collectively, this work shows the broad spectrum of available amyloid conformations, and thereby expands the foundation for studying the complex factors that interact to regulate the propagation of distinct aggregate structures.
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Affiliation(s)
- Vincent J. Huang
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Kevin C. Stein
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Heather L. True
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
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Miller MB, Wang DW, Wang F, Noble GP, Ma J, Woods VL, Li S, Supattapone S. Cofactor molecules induce structural transformation during infectious prion formation. Structure 2013; 21:2061-8. [PMID: 24120764 DOI: 10.1016/j.str.2013.08.025] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 08/30/2013] [Accepted: 08/30/2013] [Indexed: 12/12/2022]
Abstract
The spread of misfolded proteins may occur in many neurodegenerative diseases. Mammalian prions are currently the only misfolded proteins in which high specific biological infectivity can be produced in vitro. Using a system that generates infectious prions de novo from purified recombinant PrP and conversion cofactors palmitoyl-oleoyl-phosphatidylglycerol (POPG) and RNA, we examined by deuterium exchange mass spectrometry (DXMS) the stepwise protein conformational changes that occur during prion formation. We found that initial incubation with POPG causes major structural changes in PrP involving all three α helices and one β strand, with subsequent addition of RNA rendering the N terminus highly exposed. Final conversion into the infectious PrP(Sc) form was accompanied by globally decreased solvent exposure, with persistence of the major cofactor-induced conformational features. Thus, we report that cofactor molecules appear to induce major structural rearrangements during prion formation, initiating a dynamic sequence of conformational changes resulting in biologically active prions.
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Affiliation(s)
- Michael B Miller
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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54
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Haldiman T, Kim C, Cohen Y, Chen W, Blevins J, Qing L, Cohen ML, Langeveld J, Telling GC, Kong Q, Safar JG. Co-existence of distinct prion types enables conformational evolution of human PrPSc by competitive selection. J Biol Chem 2013; 288:29846-61. [PMID: 23974118 DOI: 10.1074/jbc.m113.500108] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The unique phenotypic characteristics of mammalian prions are thought to be encoded in the conformation of pathogenic prion proteins (PrP(Sc)). The molecular mechanism responsible for the adaptation, mutation, and evolution of prions observed in cloned cells and upon crossing the species barrier remains unsolved. Using biophysical techniques and conformation-dependent immunoassays in tandem, we isolated two distinct populations of PrP(Sc) particles with different conformational stabilities and aggregate sizes, which frequently co-exist in the most common human prion disease, sporadic Creutzfeldt-Jakob disease. The protein misfolding cyclic amplification replicates each of the PrP(Sc) particle types independently and leads to the competitive selection of those with lower initial conformational stability. In serial propagation with a nonglycosylated mutant PrP(C) substrate, the dominant PrP(Sc) conformers are subject to further evolution by natural selection of the subpopulation with the highest replication rate due to its lowest stability. Cumulatively, the data show that sporadic Creutzfeldt-Jakob disease PrP(Sc) is not a single conformational entity but a dynamic collection of two distinct populations of particles. This implies the co-existence of different prions, whose adaptation and evolution are governed by the selection of progressively less stable, faster replicating PrP(Sc) conformers.
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55
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Vrentas CE, Greenlee JJ, Baron T, Caramelli M, Czub S, Nicholson EM. Stability properties of PrP(Sc) from cattle with experimental transmissible spongiform encephalopathies: use of a rapid whole homogenate, protease-free assay. BMC Vet Res 2013; 9:167. [PMID: 23945217 PMCID: PMC3751458 DOI: 10.1186/1746-6148-9-167] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 08/12/2013] [Indexed: 12/01/2022] Open
Abstract
Background Transmissible Spongiform Encephalopathies (TSEs), including scrapie in sheep, chronic wasting disease (CWD) in cervids, transmissible mink encephalopathy (TME), and bovine spongiform encephalopathy (BSE), are fatal diseases of the nervous system associated with accumulation of misfolded prion protein (PrPSc). Different strains of TSEs exist, associated with different PrPSc conformations that can be probed by the stability assay, in which PrPSc is treated with increasing concentrations of the denaturant guanidine hydrochloride (GdnHCl). Results Here, we provide the first comprehensive application of a rapid, protease-free version of the GdnHCl stability assay to brain tissue from cattle experimentally infected with various TSE isolates. Consistent with previous findings from a single Japanese isolate, the L-type isolates of BSE are not distinguishable from classical BSE in this assay. In contrast, H-type isolates of BSE, including our unique isolate of E211K BSE, exhibit higher stability than classical BSE, suggesting that its increased protection against protease digestion at the BSE N-terminus is associated with a higher stability in GdnHCl. While the difference in stability in our version of the assay is likely not large enough for effective use in a diagnostic laboratory setting, the use of alternative experimental conditions may enhance this effect. TSEs from other natural host species that have been passaged in cattle, including CWD and TME, were not distinguishable from classical BSE, while isolates of cattle passaged scrapie exhibited a slight increase in stability as compared to classical BSE. Conclusions These results suggest that the core of PrPSc, as probed in this assay, has similar stability properties among cattle-passaged TSE isolates and that the conformational differences that lead to changes in the proteinase K cleavage site do not cause large changes in the stability of PrPSc from TSE-affected cattle. However, the stability differences observed here will provide a basis of comparison for new isolates of atypical BSE observed in the future and in other geographic locations, especially in the case of H-type BSE.
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Affiliation(s)
- Catherine E Vrentas
- Virus and Prion Disease Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA
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56
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Saverioni D, Notari S, Capellari S, Poggiolini I, Giese A, Kretzschmar HA, Parchi P. Analyses of protease resistance and aggregation state of abnormal prion protein across the spectrum of human prions. J Biol Chem 2013; 288:27972-85. [PMID: 23897825 DOI: 10.1074/jbc.m113.477547] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Prion diseases are characterized by tissue accumulation of a misfolded, β-sheet-enriched isoform (scrapie prion protein (PrP(Sc))) of the cellular prion protein (PrP(C)). At variance with PrP(C), PrP(Sc) shows a partial resistance to protease digestion and forms highly aggregated and detergent-insoluble polymers, two properties that have been consistently used to distinguish the two proteins. In recent years, however, the idea that PrP(Sc) itself comprises heterogeneous species has grown. Most importantly, a putative proteinase K (PK)-sensitive form of PrP(Sc) (sPrP(Sc)) is being increasingly investigated for its possible role in prion infectivity, neurotoxicity, and strain variability. The study of sPrP(Sc), however, remains technically challenging because of the need of separating it from PrP(C) without using proteases. In this study, we have systematically analyzed both PK resistance and the aggregation state of purified PrP(Sc) across the whole spectrum of the currently characterized human prion strains. The results show that PrP(Sc) isolates manifest significant strain-specific differences in their PK digestion profile that are only partially explained by differences in the size of aggregates, suggesting that other factors, likely acting on PrP(Sc) aggregate stability, determine its resistance to proteolysis. Fully protease-sensitive low molecular weight aggregates were detected in all isolates but in a limited proportion of the overall PrP(Sc) (i.e. <10%), arguing against a significant role of slowly sedimenting PK-sensitive PrP(Sc) in the biogenesis of prion strains. Finally, we highlight the limitations of current operational definitions of sPrP(Sc) and of the quantitative analytical measurements that are not based on the isolation of a fully PK-sensitive PrP(Sc) form.
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Affiliation(s)
- Daniela Saverioni
- From the Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto delle Scienze Neurologiche di Bologna, 40139 Bologna, Italy
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57
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PrP(ST), a soluble, protease resistant and truncated PrP form features in the pathogenesis of a genetic prion disease. PLoS One 2013; 8:e69583. [PMID: 23922744 PMCID: PMC3724911 DOI: 10.1371/journal.pone.0069583] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/12/2013] [Indexed: 12/29/2022] Open
Abstract
While the conversion of PrP(C) into PrP(Sc) in the transmissible form of prion disease requires a preexisting PrP(Sc) seed, in genetic prion disease accumulation of disease related PrP could be associated with biochemical and metabolic modifications resulting from the designated PrP mutation. To investigate this possibility, we looked into the time related changes of PrP proteins in the brains of TgMHu2ME199K/wt mice, a line modeling for heterozygous genetic prion disease linked to the E200K PrP mutation. We found that while oligomeric entities of mutant E199KPrP exist at all ages, aggregates of wt PrP in the same brains presented only in advanced disease, indicating a late onset conversion process. We also show that most PK resistant PrP in TgMHu2ME199K mice is soluble and truncated (PrP(ST)), a pathogenic form never before associated with prion disease. We next looked into brain samples from E200K patients and found that both PK resistant PrPs, PrP(ST) as in TgMHu2ME199K mice, and "classical" PrP(Sc) as in infectious prion diseases, coincide in the patient's post mortem brains. We hypothesize that aberrant metabolism of mutant PrPs may result in the formation of previously unknown forms of the prion protein and that these may be central for the fatal outcome of the genetic prion condition.
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58
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Pirisinu L, Nonno R, Esposito E, Benestad SL, Gambetti P, Agrimi U, Zou WQ. Small ruminant nor98 prions share biochemical features with human gerstmann-sträussler-scheinker disease and variably protease-sensitive prionopathy. PLoS One 2013; 8:e66405. [PMID: 23826096 PMCID: PMC3691246 DOI: 10.1371/journal.pone.0066405] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 05/06/2013] [Indexed: 01/08/2023] Open
Abstract
Prion diseases are classically characterized by the accumulation of pathological prion protein (PrPSc) with the protease resistant C-terminal fragment (PrPres) of 27–30 kDa. However, in both humans and animals, prion diseases with atypical biochemical features, characterized by PK-resistant PrP internal fragments (PrPres) cleaved at both the N and C termini, have been described. In this study we performed a detailed comparison of the biochemical features of PrPSc from atypical prion diseases including human Gerstmann-Sträussler-Scheinker disease (GSS) and variably protease-sensitive prionopathy (VPSPr) and in small ruminant Nor98 or atypical scrapie. The kinetics of PrPres production and its cleavage sites after PK digestion were analyzed, along with the PrPSc conformational stability, using a new method able to characterize both protease-resistant and protease-sensitive PrPSc components. All these PrPSc types shared common and distinctive biochemical features compared to PrPSc from classical prion diseases such as sporadic Creutzfeldt-Jakob disease and scrapie. Notwithstanding, distinct biochemical signatures based on PrPres cleavage sites and PrPSc conformational stability were identified in GSS A117V, GSS F198S, GSS P102L and VPSPr, which allowed their specific identification. Importantly, the biochemical properties of PrPSc from Nor98 and GSS P102L largely overlapped, but were distinct from the other human prions investigated. Finally, our study paves the way towards more refined comparative approaches to the characterization of prions at the animal–human interface.
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Affiliation(s)
- Laura Pirisinu
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
- * E-mail: (LP); (WQZ)
| | - Romolo Nonno
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | - Elena Esposito
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | | | - Pierluigi Gambetti
- Department of Pathology, National Prion Disease Pathology Surveillance Center, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Umberto Agrimi
- Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy
| | - Wen-Quan Zou
- Department of Pathology, National Prion Disease Pathology Surveillance Center, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- * E-mail: (LP); (WQZ)
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59
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Vrentas CE, Greenlee JJ, Tatum TL, Nicholson EM. Relationships between PrPSc stability and incubation time for United States scrapie isolates in a natural host system. PLoS One 2012; 7:e43060. [PMID: 22916207 PMCID: PMC3419241 DOI: 10.1371/journal.pone.0043060] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 07/18/2012] [Indexed: 11/23/2022] Open
Abstract
Transmissible spongiform encephalopathies (TSEs), including scrapie in sheep (Ovis aries), are fatal neurodegenerative diseases caused by the misfolding of the cellular prion protein (PrPC) into a â-rich conformer (PrPSc) that accumulates into higher-order structures in the brain and other tissues. Distinct strains of TSEs exist, characterized by different pathologic profiles upon passage into rodents and representing distinct conformations of PrPSc. One biochemical method of distinguishing strains is the stability of PrPSc as determined by unfolding in guanidine hydrochloride (GdnHCl), which is tightly and positively correlated with the incubation time of disease upon passage into mice. Here, we utilize a rapid, protease-free version of the stability assay to characterize naturally occurring scrapie samples, including a fast-acting scrapie inoculum for which incubation time is highly dependent on the amino acid at codon 136 of the prion protein. We utilize the stability methodology to identify the presence of two distinct isolates in the inoculum, and compare isolate properties to those of a host-stabilized reference scrapie isolate (NADC 13-7) in order to assess the stability/incubation time correlation in a natural host system. We demonstrate the utility of the stability methodology in characterizing TSE isolates throughout serial passage in livestock, which is applicable to a range of natural host systems, including strains of bovine spongiform encephalopathy and chronic wasting disease.
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Affiliation(s)
- Catherine E. Vrentas
- National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, United States of America
| | - Justin J. Greenlee
- National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, United States of America
| | - Trudy L. Tatum
- National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, United States of America
| | - Eric M. Nicholson
- National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, United States of America
- * E-mail:
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60
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Kim C, Haldiman T, Surewicz K, Cohen Y, Chen W, Blevins J, Sy MS, Cohen M, Kong Q, Telling GC, Surewicz WK, Safar JG. Small protease sensitive oligomers of PrPSc in distinct human prions determine conversion rate of PrP(C). PLoS Pathog 2012; 8:e1002835. [PMID: 22876179 PMCID: PMC3410855 DOI: 10.1371/journal.ppat.1002835] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
The mammalian prions replicate by converting cellular prion protein (PrPC) into pathogenic conformational isoform (PrPSc). Variations in prions, which cause different disease phenotypes, are referred to as strains. The mechanism of high-fidelity replication of prion strains in the absence of nucleic acid remains unsolved. We investigated the impact of different conformational characteristics of PrPSc on conversion of PrPC in vitro using PrPSc seeds from the most frequent human prion disease worldwide, the Creutzfeldt-Jakob disease (sCJD). The conversion potency of a broad spectrum of distinct sCJD prions was governed by the level, conformation, and stability of small oligomers of the protease-sensitive (s) PrPSc. The smallest most potent prions present in sCJD brains were composed only of∼20 monomers of PrPSc. The tight correlation between conversion potency of small oligomers of human sPrPSc observed in vitro and duration of the disease suggests that sPrPSc conformers are an important determinant of prion strain characteristics that control the progression rate of the disease. Mammalian prion diseases were originally characterized by accumulation of protease-resistant prion protein (PrPSc), often forming large amyloid deposits and fibrils. However, the apparent absence of protease-resistant PrPSc or amyloid fibrils in growing number of prion diseases raised several fundamental questions; specifically, whether presumably protease-sensitive forms of PrPSc exist as distinct conformers; and whether they comprise the initial steps in prion replication or are related to the alternative misfolding pathway generating noninfectious aggregates. We investigated the conformational characteristics of protease sensitive conformers of PrPSc and their role in the pathogenesis of sporadic Creutzfeldt-Jakob disease (sCJD). Using two different in vitro prion protein (PrPC) conversion techniques in tandem with biophysical methods, we identified small oligomers of protease sensitive PrPSc present in sCJD brains as the most potent initiators of PrPC conversion. Their concentration and conformational stability determine the distinctly different replication potency of PrPSc in individual isolates of sCJD and each of these characteristics correlates tightly with duration of the disease. These features argue for a broad range of distinct prion strains causing the sCJD and imply that small oligomers of protease sensitive conformers of pathogenic prion protein are encoding incubation time and progression rate of the disease.
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Affiliation(s)
- Chae Kim
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Tracy Haldiman
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Krystyna Surewicz
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Yvonne Cohen
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Wei Chen
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Janis Blevins
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Man-Sun Sy
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Mark Cohen
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Qingzhong Kong
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Glenn C. Telling
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Witold K. Surewicz
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Jiri G. Safar
- National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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61
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Abstract
The yeast, fungal and mammalian prions determine heritable and infectious traits that are encoded in alternative conformations of proteins. They cause lethal sporadic, familial and infectious neurodegenerative conditions in man, including Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), kuru, sporadic fatal insomnia (SFI) and likely variable protease-sensitive prionopathy (VPSPr). The most prevalent of human prion diseases is sporadic (s)CJD. Recent advances in amplification and detection of prions led to considerable optimism that early and possibly preclinical diagnosis and therapy might become a reality. Although several drugs have already been tested in small numbers of sCJD patients, there is no clear evidence of any agent’s efficacy. Therefore, it remains crucial to determine the full spectrum of sCJD prion strains and the conformational features in the pathogenic human prion protein governing replication of sCJD prions. Research in this direction is essential for the rational development of diagnostic as well as therapeutic strategies. Moreover, there is growing recognition that fundamental processes involved in human prion propagation – intercellular induction of protein misfolding and seeded aggregation of misfolded host proteins – are of far wider significance. This insight leads to new avenues of research in the ever-widening spectrum of age-related human neurodegenerative diseases that are caused by protein misfolding and that pose a major challenge for healthcare.
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Affiliation(s)
- Jiri G Safar
- Department of Pathology, National Prion Disease Surveillance Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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62
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Biochemical properties of highly neuroinvasive prion strains. PLoS Pathog 2012; 8:e1002522. [PMID: 22319450 PMCID: PMC3271082 DOI: 10.1371/journal.ppat.1002522] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 12/21/2011] [Indexed: 11/24/2022] Open
Abstract
Infectious prions propagate from peripheral entry sites into the central nervous system (CNS), where they cause progressive neurodegeneration that ultimately leads to death. Yet the pathogenesis of prion disease can vary dramatically depending on the strain, or conformational variant of the aberrantly folded and aggregated protein, PrPSc. Although most prion strains invade the CNS, some prion strains cannot gain entry and do not cause clinical signs of disease. The conformational basis for this remarkable variation in the pathogenesis among strains is unclear. Using mouse-adapted prion strains, here we show that highly neuroinvasive prion strains primarily form diffuse aggregates in brain and are noncongophilic, conformationally unstable in denaturing conditions, and lead to rapidly lethal disease. These neuroinvasive strains efficiently generate PrPSc over short incubation periods. In contrast, the weakly neuroinvasive prion strains form large fibrillary plaques and are stable, congophilic, and inefficiently generate PrPSc over long incubation periods. Overall, these results indicate that the most neuroinvasive prion strains are also the least stable, and support the concept that the efficient replication and unstable nature of the most rapidly converting prions may be a feature linked to their efficient spread into the CNS. Prion diseases are fatal neurodegenerative disorders that are also infectious. Prions are composed of a misfolded, aggregated form of a normal cellular protein that is highly expressed in neurons. Prion- infected individuals show variability in the clinical signs and brain regions that selectively accumulate prions, even within the same species expressing the same prion protein sequence. The basis of these divergent disease phenotypes is unclear, but is thought to be due to different conformations of the misfolded prion protein, known as strains. Here we characterized the neuropathology and biochemical properties of prion strains that efficiently or poorly invade the CNS from their peripheral entry site. We show that prion strains that efficiently invade the CNS also cause a rapidly terminal disease after an intracerebral exposure. These rapidly lethal strains were unstable when exposed to denaturants or high temperatures, and efficiently accumulated misfolded prion protein over a short incubation period in vivo. Our findings indicate that the most invasive, rapidly spreading strains are also the least conformationally stable.
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