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Stepanchuk A, Tahir W, Nilsson KPR, Schatzl HM, Stys PK. Early detection of prion protein aggregation with a fluorescent pentameric oligothiophene probe using spectral confocal microscopy. J Neurochem 2020; 156:1033-1048. [PMID: 32799317 DOI: 10.1111/jnc.15148] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/14/2020] [Accepted: 07/31/2020] [Indexed: 11/30/2022]
Abstract
Misfolding of the prion protein (PrP) and templating of its pathological conformation onto cognate proteins causes a number of lethal disorders of central nervous system in humans and animals, such as Creutzfeldt-Jacob disease, chronic wasting disease and bovine spongiform encephalopathy. Structural rearrangement of PrPC into PrPSc promotes aggregation of misfolded proteins into β-sheet-rich fibrils, which can be visualized by conformationally sensitive fluorescent probes. Early detection of prion misfolding and deposition might provide useful insights into its pathophysiology. Pentameric formyl thiophene acetic acid (pFTAA) is a novel amyloid probe that was shown to sensitively detect various misfolded proteins, including PrP. Here, we compared sensitivity of pFTAA staining and spectral microscopy with conventional methods of prion detection in mouse brains infected with mouse-adapted 22L prions. pFTAA bound to prion deposits in mouse brain sections exhibited a red-shifted fluorescence emission spectrum, which quantitatively increased with disease progression. Small prion deposits were detected as early as 50 days post-inoculation, well before appearance of clinical signs. Moreover, we detected significant spectral shifts in the greater brain parenchyma as early as 25 days post-inoculation, rivaling the most sensitive conventional method (real-time quaking-induced conversion). These results showcase the potential of pFTAA staining combined with spectral imaging for screening of prion-infected tissue. Not only does this method have comparable sensitivity to established techniques, it is faster and technically simpler. Finally, this readout provides valuable information about the spatial distribution of prion aggregates across tissue in the earliest stages of infection, potentially providing valuable pathophysiological insight into prion transmission.
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Affiliation(s)
- Anastasiia Stepanchuk
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Waqas Tahir
- Calgary Prion Research Unit, Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - K Peter R Nilsson
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Hermann M Schatzl
- Calgary Prion Research Unit, Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Peter K Stys
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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2
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Fehlinger A, Wolf H, Hossinger A, Duernberger Y, Pleschka C, Riemschoss K, Liu S, Bester R, Paulsen L, Priola SA, Groschup MH, Schätzl HM, Vorberg IM. Prion strains depend on different endocytic routes for productive infection. Sci Rep 2017; 7:6923. [PMID: 28761068 PMCID: PMC5537368 DOI: 10.1038/s41598-017-07260-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/27/2017] [Indexed: 01/08/2023] Open
Abstract
Prions are unconventional agents composed of misfolded prion protein that cause fatal neurodegenerative diseases in mammals. Prion strains induce specific neuropathological changes in selected brain areas. The mechanism of strain-specific cell tropism is unknown. We hypothesised that prion strains rely on different endocytic routes to invade and replicate within their target cells. Using prion permissive cells, we determined how impairment of endocytosis affects productive infection by prion strains 22L and RML. We demonstrate that early and late stages of prion infection are differentially sensitive to perturbation of clathrin- and caveolin-mediated endocytosis. Manipulation of canonical endocytic pathways only slightly influenced prion uptake. However, blocking the same routes had drastic strain-specific consequences on the establishment of infection. Our data argue that prion strains use different endocytic pathways for infection and suggest that cell type-dependent differences in prion uptake could contribute to host cell tropism.
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Affiliation(s)
- Andrea Fehlinger
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Hanna Wolf
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - André Hossinger
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Yvonne Duernberger
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Catharina Pleschka
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Katrin Riemschoss
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Shu Liu
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Romina Bester
- Institut für Virologie, Technische Universität München, Trogerstr. 30, 81675, München, Germany
| | - Lydia Paulsen
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Suzette A Priola
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT, 59840, USA
| | - Martin H Groschup
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, 17493, Greifswald-Insel Riems, Germany
| | - Hermann M Schätzl
- Dept. of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Ina M Vorberg
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany. .,Department of Neurology, Rheinische Friedrich-Wilhelms-Universität, 53127, Bonn, Germany.
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3
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Moda F, T. Le TN, Aulić S, Bistaffa E, Campagnani I, Virgilio T, Indaco A, Palamara L, Andréoletti O, Tagliavini F, Legname G. Synthetic prions with novel strain-specified properties. PLoS Pathog 2015; 11:e1005354. [PMID: 26720726 PMCID: PMC4699842 DOI: 10.1371/journal.ppat.1005354] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/30/2015] [Indexed: 01/10/2023] Open
Abstract
Prions are infectious proteins that possess multiple self-propagating structures. The information for strains and structural specific barriers appears to be contained exclusively in the folding of the pathological isoform, PrPSc. Many recent studies determined that de novo prion strains could be generated in vitro from the structural conversion of recombinant (rec) prion protein (PrP) into amyloidal structures. Our aim was to elucidate the conformational diversity of pathological recPrP amyloids and their biological activities, as well as to gain novel insights in characterizing molecular events involved in mammalian prion conversion and propagation. To this end we generated infectious materials that possess different conformational structures. Our methodology for the prion conversion of recPrP required only purified rec full-length mouse (Mo) PrP and common chemicals. Neither infected brain extracts nor amplified PrPSc were used. Following two different in vitro protocols recMoPrP converted to amyloid fibrils without any seeding factor. Mouse hypothalamic GT1 and neuroblastoma N2a cell lines were infected with these amyloid preparations as fast screening methodology to characterize the infectious materials. Remarkably, a large number of amyloid preparations were able to induce the conformational change of endogenous PrPC to harbor several distinctive proteinase-resistant PrP forms. One such preparation was characterized in vivo habouring a synthetic prion with novel strain specified neuropathological and biochemical properties. Prions are infectious proteins capable of acquiring multiple self-propagating structures. The information for strains and structural specific barriers appears to be contained exclusively in the folding of the pathological isoform, designated as PrPSc. During propagation, disease-associated conformer PrPSc coerces the physiological form, denoted as PrPC, to adopt the pathological isoform conformation. We describe here the generation of an array of infectious materials with different structural, morphological, biochemical and cell biological characteristics. After producing purified recombinant prion protein of the wild-type mouse full-length sequence in Escherichia coli, we polymerized the protein into various amyloid fibril conformations based on different amyloid preparations. We also applied a build-in methodology for screening amyloid preparations and generate infectious materials using an amyloid-infected cell culture assay. Some of the amyloid fibrils preparations were able to efficiently amplify in PMCA (Protein Misfolding Cyclic Amplification), and to induce endogenous PrPC to convert into PrPSc in both murine hypothalamic GT1 and neuroblastoma N2a cell lines. One such protocol lead to the generation of a novel synthetic prion strain in mice.
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Affiliation(s)
- Fabio Moda
- Unit of Neuropathology and Neurology 5, IRCCS Foundation Carlo Besta Neurological Institute, Milano, Italy
| | - Thanh-Nhat T. Le
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Ital,y
| | - Suzana Aulić
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Ital,y
| | - Edoardo Bistaffa
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Ital,y
| | - Ilaria Campagnani
- Unit of Neuropathology and Neurology 5, IRCCS Foundation Carlo Besta Neurological Institute, Milano, Italy
| | - Tommaso Virgilio
- Unit of Neuropathology and Neurology 5, IRCCS Foundation Carlo Besta Neurological Institute, Milano, Italy
| | - Antonio Indaco
- Unit of Neuropathology and Neurology 5, IRCCS Foundation Carlo Besta Neurological Institute, Milano, Italy
| | - Luisa Palamara
- Unit of Neuropathology and Neurology 5, IRCCS Foundation Carlo Besta Neurological Institute, Milano, Italy
| | - Olivier Andréoletti
- UMR INRA-ENVT, Physiopathologie Infectieuse et Parasitaire des Ruminants, Ecole Nationale Vétérinaire de Toulouse, Toulouse, France
| | - Fabrizio Tagliavini
- Unit of Neuropathology and Neurology 5, IRCCS Foundation Carlo Besta Neurological Institute, Milano, Italy
| | - Giuseppe Legname
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Ital,y
- ELETTRA Laboratory, Sincrotrone Trieste S.C.p.A, Basovizza, Trieste, Italy
- * E-mail:
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Marijanovic Z, Caputo A, Campana V, Zurzolo C. Identification of an intracellular site of prion conversion. PLoS Pathog 2009; 5:e1000426. [PMID: 19424437 PMCID: PMC2673690 DOI: 10.1371/journal.ppat.1000426] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 04/13/2009] [Indexed: 01/01/2023] Open
Abstract
Prion diseases are fatal, neurodegenerative disorders in humans and animals and are characterized by the accumulation of an abnormally folded isoform of the cellular prion protein (PrPC), denoted PrPSc, which represents the major component of infectious scrapie prions. Characterization of the mechanism of conversion of PrPC into PrPSc and identification of the intracellular site where it occurs are among the most important questions in prion biology. Despite numerous efforts, both of these questions remain unsolved. We have quantitatively analyzed the distribution of PrPC and PrPSc and measured PrPSc levels in different infected neuronal cell lines in which protein trafficking has been selectively impaired. Our data exclude roles for both early and late endosomes and identify the endosomal recycling compartment as the likely site of prion conversion. These findings represent a fundamental step towards understanding the cellular mechanism of prion conversion and will allow the development of new therapeutic approaches for prion diseases. The misfolded form (PrPSc or prion) of the naturally occuring prion protein (PrPC or cellular PrP) is responsible for neurodegenerative diseases such as Creutzfeldt-Jakob disease (CJD), bovine spongiform encephalopathy (BSE) (also known as ‘mad cow disease’) and a new variant of CJD (vCJD), which is thought to be caused by ingestion of cattle-derived foodstuffs contaminated with prions. These diseases are characterized by the accumulation of protein deposits in the central nervous system (CNS). However, unlike other neurodegenerative diseases, prion diseases are infectious and prions are able to propagate in a chain reaction by imposing their malconformed state onto the properly folded cellular proteins. Understanding where the conversion of PrPC into PrPSc occurs in cells has been an unsolved question until now. By analysing the intracellular localization of PrPC and PrPSc and measuring the levels of PrPSc produced in infected neuronal cell lines under conditions in which intracellular trafficking of the protein is impaired, we found that prion conversion occurs in the endosomal recycling compartment (ERC) where it transits after being internalized from the cell surface. This study will help to clarify the cellular mechanism of the disease and it opens the way to new therapeutic strategies aimed at the conversion compartment.
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Affiliation(s)
- Zrinka Marijanovic
- Institut Pasteur, Unité Trafic Membranaire et Pathogénèse, Paris, France
| | - Anna Caputo
- Institut Pasteur, Unité Trafic Membranaire et Pathogénèse, Paris, France
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università degli Studi di Napoli ‘Federico II’, Naples, Italy
| | - Vincenza Campana
- Institut Pasteur, Unité Trafic Membranaire et Pathogénèse, Paris, France
| | - Chiara Zurzolo
- Institut Pasteur, Unité Trafic Membranaire et Pathogénèse, Paris, France
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università degli Studi di Napoli ‘Federico II’, Naples, Italy
- * E-mail: or
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5
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Godsave SF, Wille H, Kujala P, Latawiec D, DeArmond SJ, Serban A, Prusiner SB, Peters PJ. Cryo-immunogold electron microscopy for prions: toward identification of a conversion site. J Neurosci 2008; 28:12489-99. [PMID: 19020041 PMCID: PMC2796247 DOI: 10.1523/jneurosci.4474-08.2008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 10/05/2008] [Indexed: 11/21/2022] Open
Abstract
Prion diseases are caused by accumulation of an abnormally folded isoform (PrP(Sc)) of the cellular prion protein (PrP(C)). The subcellular distribution of PrP(Sc) and the site of its formation in brain are still unclear. We performed quantitative cryo-immunogold electron microscopy on hippocampal sections from mice infected with the Rocky Mountain Laboratory strain of prions. Two antibodies were used: R2, which recognizes both PrP(C) and PrP(Sc); and F4-31, which only detects PrP(C) in undenatured sections. At a late subclinical stage of prion infection, both PrP(C) and PrP(Sc) were detected principally on neuronal plasma membranes and on vesicles resembling early endocytic or recycling vesicles in the neuropil. The R2 labeling was approximately six times higher in the infected than the uninfected hippocampus and gold clusters were only evident in infected tissue. The biggest increase in labeling density (24-fold) was found on the early/recycling endosome-like vesicles of small-diameter neurites, suggesting these as possible sites of conversion. Trypsin digestion of infected hippocampal sections resulted in a reduction in R2 labeling of >85%, which suggests that a high proportion of PrP(Sc) may be oligomeric, protease-sensitive PrP(Sc).
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Affiliation(s)
- Susan F. Godsave
- Section of Tumor Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Holger Wille
- Institute for Neurodegenerative Diseases, and
- Departments of Neurology and
| | - Pekka Kujala
- Section of Tumor Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Diane Latawiec
- Institute for Neurodegenerative Diseases, and
- Departments of Neurology and
| | - Stephen J. DeArmond
- Institute for Neurodegenerative Diseases, and
- Departments of Neurology and
- Pathology, University of California, San Francisco, San Francisco, California 94143
| | - Ana Serban
- Institute for Neurodegenerative Diseases, and
| | | | - Peter J. Peters
- Section of Tumor Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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6
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Kretlow A, Wang Q, Beekes M, Naumann D, Miller LM. Changes in protein structure and distribution observed at pre-clinical stages of scrapie pathogenesis. Biochim Biophys Acta Mol Basis Dis 2008; 1782:559-65. [PMID: 18625306 DOI: 10.1016/j.bbadis.2008.06.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 06/02/2008] [Accepted: 06/03/2008] [Indexed: 01/19/2023]
Abstract
Scrapie is a neurodegenerative disorder that involves the misfolding, aggregation and accumulation of the prion protein (PrP). The normal cellular PrP (PrP(C)) is rich in alpha-helical secondary structure, whereas the disease-associated pathogenic form of the protein (PrP(Sc)) has an anomalously high beta-sheet content. In this study, protein structural changes were examined in situ in the dorsal root ganglia from perorally 263K scrapie-infected and mock-infected hamsters using synchrotron Fourier Transform InfraRed Microspectroscopy (FTIRM) at four time points over the course of the disease (pre-clinical, 100 and 130 days post-infection (dpi); first clinical signs ( approximately 145 dpi); and terminal ( approximately 170 dpi)). Results showed clear changes in the total protein content, structure, and distribution as the disease progressed. At pre-clinical time points, the scrapie-infected animals exhibited a significant increase in protein expression, but the beta-sheet protein content was significantly lower than controls. Based on these findings, we suggest that the pre-clinical stages of scrapie are characterized by an overexpression of proteins low in beta-sheet content. As the disease progressed, the beta-sheet content increased significantly. Immunostaining with a PrP-specific antibody, 3F4, confirmed that this increase was partly - but not solely - due to the formation of PrP(Sc) in the tissue and indicated that other proteins high in beta-sheet were produced, either by overexpression or misfolding. Elevated beta-sheet was observed near the cell membrane at pre-clinical time points and also in the cytoplasm of infected neurons at later stages of infection. At the terminal stage of the disease, the protein expression declined significantly, likely due to degeneration and death of neurons. These dramatic changes in protein content and structure, especially at pre-clinical time points, emphasize the possibility for identifying other proteins involved in early pathogenesis, which are important for a further understanding of the disease.
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Affiliation(s)
- Ariane Kretlow
- P25, Robert Koch-Institut, Nordufer 20, 13353 Berlin, Germany
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Molina-Holgado F, Hider RC, Gaeta A, Williams R, Francis P. Metals ions and neurodegeneration. Biometals 2007; 20:639-54. [PMID: 17294125 DOI: 10.1007/s10534-006-9033-z] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 07/20/2006] [Indexed: 10/23/2022]
Abstract
Neurodegenerative disorders include a variety of pathological conditions, which share similar critical metabolic processes such as protein aggregation and oxidative stress, both of which are associated with the involvement of metal ions. In this review Alzheimer's disease and Parkinson's disease are mainly discussed, with the aim of identifying common trends underlying these neurological conditions. Chelation therapy could be a valuable therapeutic approach, since metals are considered to be a pharmacological target for the rationale design of new therapeutic agents directed towards the treatment of neurodegeneration.
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8
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Gaeta A, Hider RC. The crucial role of metal ions in neurodegeneration: the basis for a promising therapeutic strategy. Br J Pharmacol 2005; 146:1041-59. [PMID: 16205720 PMCID: PMC1751240 DOI: 10.1038/sj.bjp.0706416] [Citation(s) in RCA: 270] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 07/28/2005] [Accepted: 07/30/2005] [Indexed: 11/09/2022] Open
Abstract
The variety of factors and events involved in neurodegeneration renders the subject a major challenge. Neurodegenerative disorders include a number of different pathological conditions, which share similar critical metabolic processes, such as protein aggregation and oxidative stress, both of which are associated with the involvement of metal ions. In this review, Alzheimer's disease, Parkinson's disease and prion disease are discussed, with the aim of identifying common trends underlying these devastating neurological conditions. Chelation therapy could be a valuable therapeutic approach, since metals are considered to be a pharmacological target for the rationale design of new therapeutic agents directed towards the treatment of neurodegeneration.
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Affiliation(s)
- Alessandra Gaeta
- Department of Pharmacy, King's College, Franklin-Wilkins Building, London.
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Kneipp J, Miller LM, Joncic M, Kittel M, Lasch P, Beekes M, Naumann D. In situ identification of protein structural changes in prion-infected tissue. Biochim Biophys Acta Mol Basis Dis 2003; 1639:152-8. [PMID: 14636946 DOI: 10.1016/j.bbadis.2003.08.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Transmissible spongiform encephalopathies (TSE) are fatal neurodegenerative disorders characterized by the conversion of the normal prion protein (PrP(C)) into aggregates of its pathological conformer (PrP(Sc)). The mechanism behind this structural conversion is unclear. We report the identification of disease-related protein structural differences directly within the tissue environment. Utilizing a synchrotron infrared (IR) light source, IR images of protein structure were obtained at a subcellular resolution, revealing regions of decreased alpha-helical content and elevated beta-sheet structure in and around infected neurons in the 263 K scrapie hamster model. PrP(Sc) immunostaining of the same tissue demonstrated that the elevated beta-sheet regions correspond to regions where the misfolded structure of PrP(Sc) is located. No evidence of these structural changes was observed in normal neurons.
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Affiliation(s)
- Janina Kneipp
- Robert-Koch-Institut, Nordufer 20, 13353 Berlin, Germany.
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Ersdal C, Simmons MM, Goodsir C, Martin S, Jeffrey M. Sub-cellular pathology of scrapie: coated pits are increased in PrP codon 136 alanine homozygous scrapie-affected sheep. Acta Neuropathol 2003; 106:17-28. [PMID: 12669239 DOI: 10.1007/s00401-003-0690-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2002] [Revised: 12/23/2002] [Accepted: 02/03/2003] [Indexed: 11/26/2022]
Abstract
Sub-cellular studies of transmissible spongiform encephalopathies (TSEs) have been carried out on several animal species and human beings. However, studies of optimal perfusion-fixed tissues have largely been confined to examination of rodents. Using a recently developed technique, heads of scrapie-affected sheep and controls were perfusion fixed with mixed aldehydes. The obexes were immunohistochemically labelled with PrP antibodies, and the dorsal motor nucleus of the vagal nerve was examined by electron microscopy. Irregular neuritic profiles with highly invaginated membranes, associated with coated pits were found in all scrapie-affected sheep, but not in controls. Interestingly, they were consistently more frequent in the homozygous A(136) sheep. This is the first report describing sub-cellular differences in pathology associated with different PrP genotypes. Rarely, amorphous material, or sparse fibrillar structures, were present in the extracellular space. The changes were often associated with irregular plasmalemma and frequent coated pits. Vacuolation typical of TSEs, dystrophic neurites and variable gliosis were present. Herniation of membranes and organelles from apparently healthy processes into adjacent vacuoles and dendrites was also observed. We suggest that the increase in coated pits and plasmalemma invagination is related to an attempted internalisation of aggregated disease-specific PrP, or protofilaments, from the extracellular space.
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Affiliation(s)
- Cecilie Ersdal
- Department of Sheep and Goat Research, The Norwegian School of Veterinary Science, PO Box 8146, Dep., 0033 Oslo, Norway.
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