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Fremuntova Z, Hanusova ZB, Soukup J, Mosko T, Matej R, Holada K. Simple 3D spheroid cell culture model for studies of prion infection. Eur J Neurosci 2024; 60:4437-4452. [PMID: 38887188 DOI: 10.1111/ejn.16444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 05/15/2024] [Accepted: 06/03/2024] [Indexed: 06/20/2024]
Abstract
Mouse neuronal CAD 5 cell line effectively propagates various strains of prions. Previously, we have shown that it can also be differentiated into the cells morphologically resembling neurons. Here, we demonstrate that CAD 5 cells chronically infected with prions undergo differentiation under the same conditions. To make our model more realistic, we triggered the differentiation in the 3D culture created by gentle rocking of CAD 5 cell suspension. Spheroids formed within 1 week and were fully developed in less than 3 weeks of culture. The mature spheroids had a median size of ~300 μm and could be cultured for up to 12 weeks. Increased expression of differentiation markers GAP 43, tyrosine hydroxylase, β-III-tubulin and SNAP 25 supported the differentiated status of the spheroid cells. The majority of them were found in the G0/G1 phase of the cell cycle, which is typical for differentiated cells. Moreover, half of the PrPC on the cell membrane was N-terminally truncated, similarly as in differentiated CAD 5 adherent cells. Finally, we demonstrated that spheroids could be created from prion-infected CAD 5 cells. The presence of prions was verified by immunohistochemistry, western blot and seed amplification assay. We also confirmed that the spheroids can be infected with the prions de novo. Our 3D culture model of differentiated CAD 5 cells is low cost, easy to produce and cultivable for weeks. We foresee its possible use in the testing of anti-prion compounds and future studies of prion formation dynamics.
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Affiliation(s)
- Zuzana Fremuntova
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Zdenka Backovska Hanusova
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jakub Soukup
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Tibor Mosko
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Radoslav Matej
- Department of Pathology and Molecular Medicine, Third Faculty of Medicine, Charles University and Thomayer University Hospital, Prague, Czech Republic
| | - Karel Holada
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
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2
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Walters RO, Haigh CL. Organoids for modeling prion diseases. Cell Tissue Res 2023; 392:97-111. [PMID: 35088182 PMCID: PMC9329493 DOI: 10.1007/s00441-022-03589-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/19/2022] [Indexed: 11/25/2022]
Abstract
Human cerebral organoids are an exciting and novel model system emerging in the field of neurobiology. Cerebral organoids are spheres of self-organizing, neuronal lineage tissue that can be differentiated from human pluripotent stem cells and that present the possibility of on-demand human neuronal cultures that can be used for non-invasively investigating diseases affecting the brain. Compared with existing humanized cell models, they provide a more comprehensive replication of the human cerebral environment. The potential of the human cerebral organoid model is only just beginning to be elucidated, but initial studies have indicated that they could prove to be a valuable model for neurodegenerative diseases such as prion disease. The application of the cerebral organoid model to prion disease, what has been learned so far and the future potential of this model are discussed in this review.
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Affiliation(s)
- Ryan O Walters
- Prion Cell Biology Unit, 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
| | - Cathryn L Haigh
- Prion Cell Biology Unit, 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.
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3
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Nikolić L, Ferracin C, Legname G. Recent advances in cellular models for discovering prion disease therapeutics. Expert Opin Drug Discov 2022; 17:985-996. [PMID: 35983689 DOI: 10.1080/17460441.2022.2113773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Prion diseases are a group of rare and lethal rapidly progressive neurodegenerative diseases arising due to conversion of the physiological cellular prion protein into its pathological counterparts, denoted as "prions". These agents are resistant to inactivation by standard decontamination procedures and can be transmitted between individuals, consequently driving the irreversible brain damage typical of the diseases. AREAS COVERED Since its infancy, prion research has mainly depended on animal models for untangling the pathogenesis of the disease as well as for the drug development studies. With the advent of prion-infected cell lines, relevant animal models have been complemented by a variety of cell-based models presenting a much faster, ethically acceptable alternative. EXPERT OPINION To date, there are still either no effective prophylactic regimens or therapies for human prion diseases. Therefore, there is an urgent need for more relevant cellular models that best approximate in vivo models. Each cellular model presented and discussed in detail in this review has its own benefits and limitations. Once embarking in a drug screening campaign for the identification of molecules that could interfere with prion conversion and replication, one should carefully consider the ideal cellular model.
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Affiliation(s)
- Lea Nikolić
- PhD Student in Functional and Structural Genomics, Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy,
| | - Chiara Ferracin
- PhD Student in Functional and Structural Genomics, Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Giuseppe Legname
- D.Phil., Full Professor of Biochemistry, Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
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4
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Arshad H, Watts JC. Genetically engineered cellular models of prion propagation. Cell Tissue Res 2022; 392:63-80. [PMID: 35581386 DOI: 10.1007/s00441-022-03630-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/26/2022] [Indexed: 11/02/2022]
Abstract
For over three decades, cultured cells have been a useful tool for dissecting the molecular details of prion replication and the identification of candidate therapeutics for prion disease. A major issue limiting the translatability of these studies has been the inability to reliably propagate disease-relevant, non-mouse strains of prions in cells relevant to prion pathogenesis. In recent years, fueled by advances in gene editing technology, it has become possible to propagate prions from hamsters, cervids, and sheep in immortalized cell lines originating from the central nervous system. In particular, the use of CRISPR-Cas9-mediated gene editing to generate versions of prion-permissive cell lines that lack endogenous PrP expression has provided a blank canvas upon which re-expression of PrP leads to species-matched susceptibility to prion infection. When coupled with the ability to propagate prions in cells or organoids derived from stem cells, these next-generation cellular models should provide an ideal paradigm for identifying small molecules and other biological therapeutics capable of interfering with prion replication in animal and human prion disorders. In this review, we summarize recent advances that have widened the spectrum of prion strains that can be propagated in cultured cells and cutting-edge tissue-based models.
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Affiliation(s)
- Hamza Arshad
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Tower Rm. 4KD481, 60 Leonard Ave, Toronto, ON, M5T 0S8, Canada.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Medical Sciences Building Rm. 5207, Toronto, ON, M5S 1A8, Canada
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Tower Rm. 4KD481, 60 Leonard Ave, Toronto, ON, M5T 0S8, Canada. .,Department of Biochemistry, University of Toronto, 1 King's College Circle, Medical Sciences Building Rm. 5207, Toronto, ON, M5S 1A8, Canada.
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5
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Pineau H, Sim VL. From Cell Culture to Organoids-Model Systems for Investigating Prion Strain Characteristics. Biomolecules 2021; 11:biom11010106. [PMID: 33466947 PMCID: PMC7830147 DOI: 10.3390/biom11010106] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/05/2021] [Accepted: 01/11/2021] [Indexed: 02/06/2023] Open
Abstract
Prion diseases are the hallmark protein folding neurodegenerative disease. Their transmissible nature has allowed for the development of many different cellular models of disease where prion propagation and sometimes pathology can be induced. This review examines the range of simple cell cultures to more complex neurospheres, organoid, and organotypic slice cultures that have been used to study prion disease pathogenesis and to test therapeutics. We highlight the advantages and disadvantages of each system, giving special consideration to the importance of strains when choosing a model and when interpreting results, as not all systems propagate all strains, and in some cases, the technique used, or treatment applied, can alter the very strain properties being studied.
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Affiliation(s)
- Hailey Pineau
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2B7, Canada;
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Valerie L. Sim
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2B7, Canada;
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB T6G 2R3, Canada
- Correspondence:
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6
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Krance SH, Luke R, Shenouda M, Israwi AR, Colpitts SJ, Darwish L, Strauss M, Watts JC. Cellular models for discovering prion disease therapeutics: Progress and challenges. J Neurochem 2020; 153:150-172. [PMID: 31943194 DOI: 10.1111/jnc.14956] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/22/2022]
Abstract
Prions, which cause fatal neurodegenerative disorders such as Creutzfeldt-Jakob disease, are misfolded and infectious protein aggregates. Currently, there are no treatments available to halt or even delay the progression of prion disease in the brain. The infectious nature of prions has resulted in animal paradigms that accurately recapitulate all aspects of prion disease, and these have proven to be instrumental for testing the efficacy of candidate therapeutics. Nonetheless, infection of cultured cells with prions provides a much more powerful system for identifying molecules capable of interfering with prion propagation. Certain lines of cultured cells can be chronically infected with various types of mouse prions, and these models have been used to unearth candidate anti-prion drugs that are at least partially efficacious when administered to prion-infected rodents. However, these studies have also revealed that not all types of prions are equal, and that drugs active against mouse prions are not necessarily effective against prions from other species. Despite some recent progress, the number of cellular models available for studying non-mouse prions remains limited. In particular, human prions have proven to be particularly challenging to propagate in cultured cells, which has severely hindered the discovery of drugs for Creutzfeldt-Jakob disease. In this review, we summarize the cellular models that are presently available for discovering and testing drugs capable of blocking the propagation of prions and highlight challenges that remain on the path towards developing therapies for prion disease.
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Affiliation(s)
- Saffire H Krance
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Russell Luke
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Marc Shenouda
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.,Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
| | - Ahmad R Israwi
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Sarah J Colpitts
- Department of Immunology, University of Toronto, Toronto, ON, Canada
| | - Lina Darwish
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Maximilian Strauss
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.,Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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7
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Relaño-Ginés A, Lehmann S, Crozet C. Cell-based therapy against prion diseases. Curr Opin Pharmacol 2018; 44:8-14. [PMID: 30472550 DOI: 10.1016/j.coph.2018.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 10/13/2018] [Accepted: 11/05/2018] [Indexed: 01/01/2023]
Abstract
Despite multiple efforts to find treatments, prion diseases are still incurable. The currently available therapeutic strategies are mostly based on compounds to inhibit pathological PrP (PrPSc) accumulation, and cellular PrP (PrPC) conversion into PrPSc. However, they cannot reverse the pathological changes already present in the brain. Cell-based therapeutic strategies could promote the repair of the pre-existing brain damage. The few available data come mostly from preclinical studies using neural stem cells, bone marrow-derived microglia and mesenchymal stem cells, as cell sources. Moreover, the benefits of cell-based therapeutic strategies could be linked not only to the replacement of damaged cells, but also to the secretion of trophic factors by the grafted cells that might modulate inflammation, cell death, or endogenous neurogenesis.
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Affiliation(s)
- Aroa Relaño-Ginés
- Institute for Regenerative Medicine and Biotherapies (IRMB), Neural Stem Cell, MSC and Neurodegenerative Diseases - U1183 INSERM (Institut National de la Santé et de la Recherche Médicale), 80 rue Augustin Fliche, 34295 Montpellier, France; Université de Montpellier, 163 rue Auguste Broussonet, 34090 Montpellier, France
| | - Sylvain Lehmann
- Institute for Regenerative Medicine and Biotherapies (IRMB), Neural Stem Cell, MSC and Neurodegenerative Diseases - U1183 INSERM (Institut National de la Santé et de la Recherche Médicale), 80 rue Augustin Fliche, 34295 Montpellier, France; Université de Montpellier, 163 rue Auguste Broussonet, 34090 Montpellier, France; Centre Hospitalo-Universitaire de Montpellier, 191 Av. du Doyen Gaston Giraud, 34295 Montpellier, France
| | - Carole Crozet
- Institute for Regenerative Medicine and Biotherapies (IRMB), Neural Stem Cell, MSC and Neurodegenerative Diseases - U1183 INSERM (Institut National de la Santé et de la Recherche Médicale), 80 rue Augustin Fliche, 34295 Montpellier, France.
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8
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Abstract
The development of multiple cell culture models of prion infection over the last two decades has led to a significant increase in our understanding of how prions infect cells. In particular, new techniques to distinguish exogenous from endogenous prions have allowed us for the first time to look in depth at the earliest stages of prion infection through to the establishment of persistent infection. These studies have shown that prions can infect multiple cell types, both neuronal and nonneuronal. Once in contact with the cell, they are rapidly taken up via multiple endocytic pathways. After uptake, the initial replication of prions occurs almost immediately on the plasma membrane and within multiple endocytic compartments. Following this acute stage of prion replication, persistent prion infection may or may not be established. Establishment of a persistent prion infection in cells appears to depend upon the achievement of a delicate balance between the rate of prion replication and degradation, the rate of cell division, and the efficiency of prion spread from cell to cell. Overall, cell culture models have shown that prion infection of the cell is a complex and variable process which can involve multiple cellular pathways and compartments even within a single cell.
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Affiliation(s)
- Suzette A Priola
- Laboratory of Persistent Viral Diseases, National Institute of Allergy and Infectious Diseases, Hamilton, MT, United States.
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9
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Hirsch TZ, Martin-Lannerée S, Reine F, Hernandez-Rapp J, Herzog L, Dron M, Privat N, Passet B, Halliez S, Villa-Diaz A, Lacroux C, Klein V, Haïk S, Andréoletti O, Torres JM, Vilotte JL, Béringue V, Mouillet-Richard S. Epigenetic Control of the Notch and Eph Signaling Pathways by the Prion Protein: Implications for Prion Diseases. Mol Neurobiol 2018; 56:2159-2173. [PMID: 29998397 DOI: 10.1007/s12035-018-1193-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 06/26/2018] [Indexed: 12/12/2022]
Abstract
Among the ever-growing number of self-replicating proteins involved in neurodegenerative diseases, the prion protein PrP remains the most infamous for its central role in transmissible spongiform encephalopathies (TSEs). In these diseases, pathogenic prions propagate through a seeding mechanism, where normal PrPC molecules are converted into abnormally folded scrapie isoforms termed PrPSc. Since its discovery over 30 years ago, much advance has contributed to define the host-encoded cellular prion protein PrPC as a critical relay of prion-induced neuronal cell demise. A current consensual view is that the conversion of PrPC into PrPSc in neuronal cells diverts the former from its normal function with subsequent molecular alterations affecting synaptic plasticity. Here, we report that prion infection is associated with reduced expression of key effectors of the Notch pathway in vitro and in vivo, recapitulating changes fostered by the absence of PrPC. We further show that both prion infection and PrPC depletion promote drastic alterations in the expression of a defined set of Eph receptors and their ephrin ligands, which represent important players in synaptic function. Our data indicate that defects in the Notch and Eph axes can be mitigated in response to histone deacetylase inhibition in PrPC-depleted as well as prion-infected cells. We thus conclude that infectious prions cause a loss-of-function phenotype with respect to Notch and Eph signaling and that these alterations are sustained by epigenetic mechanisms.
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Affiliation(s)
- Théo Z Hirsch
- INSERM UMR 1124, 75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, 75006, Paris, France
- INSERM U1162, 75010, Paris, France
| | - Séverine Martin-Lannerée
- INSERM UMR 1124, 75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, 75006, Paris, France
| | - Fabienne Reine
- INRA, Université Paris-Saclay, UR 892 Virologie Immunologie Moléculaires, 78350, Jouy-en-Josas, France
| | - Julia Hernandez-Rapp
- INSERM UMR 1124, 75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, 75006, Paris, France
- Centre de Recherche du CHU de Québec, Université Laval, Québec, G1V4G2, Québec, Canada
| | - Laetitia Herzog
- INRA, Université Paris-Saclay, UR 892 Virologie Immunologie Moléculaires, 78350, Jouy-en-Josas, France
| | - Michel Dron
- INRA, Université Paris-Saclay, UR 892 Virologie Immunologie Moléculaires, 78350, Jouy-en-Josas, France
| | - Nicolas Privat
- INSERM UMR 1127, CNRS UMR 7225, 75013, Paris, France
- Institut du Cerveau et de la Moelle épinière, ICM, Inserm U 1127, CNRS UMR 7225, Sorbonne Université, F-75013, Paris, France
| | - Bruno Passet
- INRA UMR1313, Génétique Animale et Biologie Intégrative, 78350, Jouy-en-Josas, France
| | - Sophie Halliez
- INRA, Université Paris-Saclay, UR 892 Virologie Immunologie Moléculaires, 78350, Jouy-en-Josas, France
- INSERM, UMR-S1172, Lille University, 59045, Lille, France
| | - Ana Villa-Diaz
- Centro de Investigación en Sanidad Animal-INIA, 28130, Madrid, Spain
| | | | - Victor Klein
- INSERM UMR 1124, 75006, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, 75006, Paris, France
| | - Stéphane Haïk
- INSERM UMR 1127, CNRS UMR 7225, 75013, Paris, France
- Institut du Cerveau et de la Moelle épinière, ICM, Inserm U 1127, CNRS UMR 7225, Sorbonne Université, F-75013, Paris, France
| | | | - Juan-Maria Torres
- Centro de Investigación en Sanidad Animal-INIA, 28130, Madrid, Spain
| | - Jean-Luc Vilotte
- INRA UMR1313, Génétique Animale et Biologie Intégrative, 78350, Jouy-en-Josas, France
| | | | - Sophie Mouillet-Richard
- INSERM UMR 1124, 75006, Paris, France.
- Université Paris Descartes, Sorbonne Paris Cité, UMR 1124, 75006, Paris, France.
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10
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Autologous neural progenitor cell transplantation into newborn mice modeling for E200K genetic prion disease delays disease progression. Neurobiol Aging 2018; 65:192-200. [DOI: 10.1016/j.neurobiolaging.2018.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 12/18/2017] [Accepted: 01/08/2018] [Indexed: 01/04/2023]
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11
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Abstract
In this issue of JEM, Krejciova et al. (https://doi.org/10.1084/jem.20161547) report that astrocytes derived from human iPSCs can replicate human CJD prions. These observations provide a new, potentially very valuable model for studying human prions in cellula and for identifying antiprion compounds that might serve as clinical candidates. Furthermore, they add to the evidence that astrocytes may not be just innocent bystanders in prion diseases.
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Affiliation(s)
- Adriano Aguzzi
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Yingjun Liu
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
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12
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Iwamaru Y, Mathiason CK, Telling GC, Hoover EA. Chronic wasting disease prion infection of differentiated neurospheres. Prion 2017; 11:277-283. [PMID: 28762865 DOI: 10.1080/19336896.2017.1336273] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
A possible strategy to develop more diverse cell culture systems permissive to infection with naturally occurring prions is to exploit culture of neurospheres from transgenic mice expressing the normal prion protein (PrP) of the native host species. Accordingly, we developed differentiated neurosphere cultures from the cervid PrP-expressing mice to investigate whether this in vitro system would support replication of non-adapted cervid-origin chronic wasting disease (CWD) prions. Here we report the successful amplification of disease-associated PrP in differentiated neurosphere cultures within 3 weeks after exposure to CWD prions from both white-tailed deer or elk. This neurosphere culture system provides a new in vitro tool that can be used to assess non-adapted CWD prion propagation and transmission.
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Affiliation(s)
- Yoshifumi Iwamaru
- a Prion Research Center, Department of Microbiology, Immunology and Pathology , College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins , CO , USA.,b Prion Disease Research Unit , National Institute of Animal Health , Tsukuba , Ibaraki , Japan
| | - Candace K Mathiason
- a Prion Research Center, Department of Microbiology, Immunology and Pathology , College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins , CO , USA
| | - Glenn C Telling
- a Prion Research Center, Department of Microbiology, Immunology and Pathology , College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins , CO , USA
| | - Edward A Hoover
- a Prion Research Center, Department of Microbiology, Immunology and Pathology , College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins , CO , USA
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13
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Abstract
Traditional primary and secondary cell cultures have been used for the investigation of prion biology and disease for many years. While both types of cultures produce highly valid and immensely valuable results, they also have their limitations; traditional cell lines are often derived from cancers, therefore subject to numerous DNA changes, and primary cultures are labor-intensive and expensive to produce requiring sacrifice of many animals. Neural stem cell (NSC) cultures are a relatively new technology to be used for the study of prion biology and disease. While NSCs are subject to their own limitations-they are generally cultured ex vivo in environments that artificially force their growth-they also have their own unique advantages. NSCs retain the ability for self-renewal and can therefore be propagated in culture similarly to secondary cultures without genetic manipulation. In addition, NSCs are multipotent; they can be induced to differentiate into mature cells of central nervous system (CNS) linage. The combination of self-renewal and multipotency allows NSCs to be used as a primary cell line over multiple generations saving time, costs, and animal harvests, thus providing a valuable addition to the existing cell culture repertoire used for investigation of prion biology and disease. Furthermore, NSC cultures can be generated from mice of any genotype, either by embryonic harvest or harvest from adult brain, allowing gene expression to be studied without further genetic manipulation. This chapter describes a standard method of culturing adult NSCs and assays for monitoring NSC growth, migration, and differentiation and revisits basic reactive oxygen species detection in the context of NSC cultures.
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Affiliation(s)
- Cathryn L Haigh
- Department of Medicine, Melbourne Brain Centre, Royal Melbourne Hospital, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3010, Australia. .,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.
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14
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Collins SJ, Haigh CL. Simplified Murine 3D Neuronal Cultures for Investigating Neuronal Activity and Neurodegeneration. Cell Biochem Biophys 2016; 75:3-13. [PMID: 27796787 DOI: 10.1007/s12013-016-0768-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/17/2016] [Indexed: 12/28/2022]
Abstract
The ability to model brain tissue in three-dimensions offers new potential for elucidating functional cellular interactions and corruption of such functions during pathogenesis. Many protocols now exist for growing neurones in three-dimensions and these vary in complexity and cost. Herein, we describe a straight-forward method for generating three-dimensional, terminally differentiated central nervous system cultures from adult murine neural stem cells. The protocol requires no specialist equipment, is not labour intensive or expensive and produces mature cultures within 10 days that can survive beyond a month. Populations of functional glutamatergic neurones could be identified within cultures. Additionally, the three dimensional neuronal cultures can be used to investigate tissue changes during the development of neurodegenerative disease where demonstration of hallmark features, such as plaque generation, has not previously been possible using two-dimensional cultures of neuronal cells. Using a prion model of acquired neurodegenerative disease, biochemical changes indicative of prion pathology were induced within 2-3 weeks in the three dimensional cultures. Our findings show that tissue differentiated in this simplified three dimensional culture model is physiologically competent to model central nervous system cellular behaviour as well as manifest the functional failures and pathological changes associated with neurodegenerative disease.
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Affiliation(s)
- Steven J Collins
- Department of Medicine (Royal Melbourne Hospital), Melbourne Brain Centre, The University of Melbourne, 30 Royal Parade, Parkville, Melbourne, VIC, 3010, Australia
| | - Cathryn L Haigh
- Department of Medicine (Royal Melbourne Hospital), Melbourne Brain Centre, The University of Melbourne, 30 Royal Parade, Parkville, Melbourne, VIC, 3010, Australia.
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15
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Martin-Lannerée S, Hirsch TZ, Hernandez-Rapp J, Halliez S, Vilotte JL, Launay JM, Mouillet-Richard S. PrP(C) from stem cells to cancer. Front Cell Dev Biol 2014; 2:55. [PMID: 25364760 PMCID: PMC4207012 DOI: 10.3389/fcell.2014.00055] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/11/2014] [Indexed: 12/23/2022] Open
Abstract
The cellular prion protein PrP(C) was initially discovered as the normal counterpart of the pathological scrapie prion protein PrP(Sc), the main component of the infectious agent of Transmissible Spongiform Encephalopathies. While clues as to the physiological function of this ubiquitous protein were greatly anticipated from the development of knockout animals, PrP-null mice turned out to be viable and to develop without major phenotypic abnormalities. Notwithstanding, the discovery that hematopoietic stem cells from PrP-null mice have impaired long-term repopulating potential has set the stage for investigating into the role of PrP(C) in stem cell biology. A wealth of data have now exemplified that PrP(C) is expressed in distinct types of stem cells and regulates their self-renewal as well as their differentiation potential. A role for PrP(C) in the fate restriction of embryonic stem cells has further been proposed. Paralleling these observations, an overexpression of PrP(C) has been documented in various types of tumors. In line with the contribution of PrP(C) to stemness and to the proliferation of cancer cells, PrP(C) was recently found to be enriched in subpopulations of tumor-initiating cells. In the present review, we summarize the current knowledge of the role played by PrP(C) in stem cell biology and discuss how the subversion of its function may contribute to cancer progression.
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Affiliation(s)
- Séverine Martin-Lannerée
- Toxicology, Pharmacology and Cellular Signaling, INSERM UMR-S1124 Paris, France ; Toxicology, Pharmacology and Cellular Signaling, Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Théo Z Hirsch
- Toxicology, Pharmacology and Cellular Signaling, INSERM UMR-S1124 Paris, France ; Toxicology, Pharmacology and Cellular Signaling, Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
| | - Julia Hernandez-Rapp
- Toxicology, Pharmacology and Cellular Signaling, INSERM UMR-S1124 Paris, France ; Toxicology, Pharmacology and Cellular Signaling, Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France ; Université Paris Sud 11, ED419 Biosigne Orsay, France
| | - Sophie Halliez
- U892 Virologie et Immunologie Moléculaires, INRA Jouy-en-Josas, France
| | - Jean-Luc Vilotte
- UMR1313 Génétique Animale et Biologie Intégrative, INRA Jouy-en-Josas, France
| | - Jean-Marie Launay
- AP-HP Service de Biochimie, Fondation FondaMental, INSERM U942 Hôpital Lariboisière Paris, France ; Pharma Research Department, F. Hoffmann-La-Roche Ltd. Basel, Switzerland
| | - Sophie Mouillet-Richard
- Toxicology, Pharmacology and Cellular Signaling, INSERM UMR-S1124 Paris, France ; Toxicology, Pharmacology and Cellular Signaling, Université Paris Descartes, Sorbonne Paris Cité, UMR-S1124 Paris, France
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Mediano DR, Sanz-Rubio D, Ranera B, Bolea R, Martín-Burriel I. The potential of mesenchymal stem cell in prion research. Zoonoses Public Health 2014; 62:165-78. [PMID: 24854140 DOI: 10.1111/zph.12138] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Indexed: 01/09/2023]
Abstract
Scrapie and bovine spongiform encephalopathy are fatal neurodegenerative diseases caused by the accumulation of a misfolded protein (PrP(res)), the pathological form of the cellular prion protein (PrP(C)). For the last decades, prion research has greatly progressed, but many questions need to be solved about prion replication mechanisms, cell toxicity, differences in genetic susceptibility, species barrier or the nature of prion strains. These studies can be developed in murine models of transmissible spongiform encephalopathies, although development of cell models for prion replication and sample titration could reduce economic and timing costs and also serve for basic research and treatment testing. Some murine cell lines can replicate scrapie strains previously adapted in mice and very few show the toxic effects of prion accumulation. Brain cell primary cultures can be more accurate models but are difficult to develop in naturally susceptible species like humans or domestic ruminants. Stem cells can be differentiated into neuron-like cells and be infected by prions. However, the use of embryo stem cells causes ethical problems in humans. Mesenchymal stem cells (MSCs) can be isolated from many adult tissues, including bone marrow, adipose tissue or even peripheral blood. These cells differentiate into neuronal cells, express PrP(C) and can be infected by prions in vitro. In addition, in the last years, these cells are being used to develop therapies for many diseases, including neurodegenerative diseases. We review here the use of cell models in prion research with a special interest in the potential use of MSCs.
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Affiliation(s)
- D R Mediano
- Facultad de Veterinaria, Laboratorio de Genética Bioquímica, Universidad de Zaragoza, Zaragoza, Spain
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Development of a novel cellular model of Alzheimer's disease utilizing neurosphere cultures derived from B6C3-Tg(APPswe,PSEN1dE9)85Dbo/J embryonic mouse brain. SPRINGERPLUS 2014; 3:161. [PMID: 25140287 PMCID: PMC4137416 DOI: 10.1186/2193-1801-3-161] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 03/07/2014] [Indexed: 12/29/2022]
Abstract
Increased production, oligomerization and aggregation of amyloid-β (Aβ) peptides are hallmark pathologies of Alzheimer’s disease (AD). Expressing familial AD mutations (amyloid precursor protein and/or presenilins mutations), the Aβ-pathologies of AD has been recapitulated in animal models of AD. Very few primary cell culture-based models of AD are available and they exhibit very weak Aβ-pathologies compared to what is seen in AD patients and animal models of AD. CNS stem/progenitor cells are present in both embryonic and adult brains. They can be isolated, grown as neurospheres and differentiated into neurons, astrocytes and oligodendrocytes. It is not yet known whether CNS stem/progenitor cells can support the production of Aβ peptides in culture. In this report, we have established Aβ-pathologies such as production, secretion, oligomerization and aggregation of Aβ peptides utilizing neurosphere cultures to create a new cellular model of AD. These cultures were developed from E15 embryonic brains of transgenic mice carrying the Swedish mutations in humanized mouse APP cDNA and the exon-9 deleted human presenilin 1 cDNA both regulated by mouse prion protein gene (Prnp) promoter. Results demonstrated the expression of transgene transcripts, APPswe protein and its processed products only in transgene positive neurosphere cultures. These cultures generate and secrete both Aβ40 and Aβ42 peptides into culture medium at levels comparable to the Aβ load in the brain of AD patients and animal models of AD, and produce pathogenic oligomers of Aβ peptides. The Aβ42/Aβ40 ratio in the medium of transgene positive neurosphere cultures is higher than any known cellular models of AD. Conformation dependent immunocytochemistry demonstrated the possible presence of intracellular and extracellular aggregation of Aβ peptides in neurosphere cultures, which are also seen in AD brain and animal models of AD. Collectively, our neurosphere cultures provide robust Aβ-pathologies of AD better than existing cellular model of Alzheimer’s disease.
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Abstract
We have demonstrated that prions accumulate to high levels in non-proliferative C2C12 myotubes. C2C12 cells replicate as myoblasts but can be differentiated into myotubes. Earlier studies indicated that C2C12 myoblasts are not competent for prion replication. (1) We confirmed that observation and demonstrated, for the first time, that while replicative myoblasts do not accumulate PrP(Sc), differentiated post-mitotic myotube cultures replicate prions robustly. Here we extend our observations and describe the implication and utility of this system for replicating prions.
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Affiliation(s)
- Allen Herbst
- Centre for Prions and Protein Folding Diseases; Department of Agricultural, Food and Nutritional Sciences; University of Alberta; Edmonton, AB Canada
| | - Judd M Aiken
- Centre for Prions and Protein Folding Diseases; Department of Agricultural, Food and Nutritional Sciences; University of Alberta; Edmonton, AB Canada
| | - Debbie McKenzie
- Centre for Prions and Protein Folding Diseases; Department of Biological Sciences; University of Alberta; Edmonton, AB Canada
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Prion replication elicits cytopathic changes in differentiated neurosphere cultures. J Virol 2013; 87:8745-55. [PMID: 23740992 DOI: 10.1128/jvi.00572-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The molecular mechanisms of prion-induced cytotoxicity remain largely obscure. Currently, only a few cell culture models have exhibited the cytopathic changes associated with prion infection. In this study, we introduced a cell culture model based on differentiated neurosphere cultures isolated from the brains of neonatal prion protein (PrP)-null mice and transgenic mice expressing murine PrP (dNP0 and dNP20 cultures). Upon exposure to mouse Chandler prions, dNP20 cultures supported the de novo formation of abnormal PrP and the resulting infectivity, as assessed by bioassays. Furthermore, this culture was susceptible to various prion strains, including mouse-adapted scrapie, bovine spongiform encephalopathy, and Gerstmann-Sträussler-Scheinker syndrome prions. Importantly, a subset of the cells in the infected culture that was mainly composed of astrocyte lineage cells consistently displayed late-occurring, progressive signs of cytotoxicity as evidenced by morphological alterations, decreased cell viability, and increased lactate dehydrogenase release. These signs of cytotoxicity were not observed in infected dNP0 cultures, suggesting the requirement of endogenous PrP expression for prion-induced cytotoxicity. Degenerated cells positive for glial fibrillary acidic protein accumulated abnormal PrP and exhibited features of apoptotic death as assessed by active caspase-3 and terminal deoxynucleotidyltransferase nick-end staining. Furthermore, caspase inhibition provided partial protection from prion-mediated cell death. These results suggest that differentiated neurosphere cultures can provide an in vitro bioassay for mouse prions and permit the study of the molecular basis for prion-induced cytotoxicity at the cellular level.
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20
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Cellular aspects of prion replication in vitro. Viruses 2013; 5:374-405. [PMID: 23340381 PMCID: PMC3564126 DOI: 10.3390/v5010374] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 01/07/2013] [Accepted: 01/16/2013] [Indexed: 12/19/2022] Open
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 β-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.
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Pradines E, Hernandez-Rapp J, Villa-Diaz A, Dakowski C, Ardila-Osorio H, Haik S, Schneider B, Launay JM, Kellermann O, Torres JM, Mouillet-Richard S. Pathogenic prions deviate PrP(C) signaling in neuronal cells and impair A-beta clearance. Cell Death Dis 2013; 4:e456. [PMID: 23303130 PMCID: PMC3563983 DOI: 10.1038/cddis.2012.195] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The subversion of the normal function exerted by the cellular prion protein (PrPC) in neurons by pathogenic prions is assumed to have a central role in the pathogenesis of transmissible spongiform encephalopathies. Using two murine models of prion infection, the 1C11 neuronal cell line and neurospheres, we document that prion infection is associated with the constitutive activation of signaling targets normally coupled with PrPC, including the Fyn kinase, the mitogen-associated protein kinases ERK1/2 and the CREB transcription factor. PrPC-dependent signaling overactivation in infected cells is associated with the recruitment of p38 and JNK stress-associated kinases. Downstream from CREB, prion-infected cells exhibit reduced activity of the matrix metalloprotease (MMP)-9. As MMP-9 catalyzes the degradation of the amyloid A-beta peptide, the decrease in MMP-9 activity in prion-infected cells causes a significant impairment of the clearance of A-beta, leading to its accumulation. By exploiting two 1C11-infected clones accumulating high or moderate levels of prions, we show that the prion-induced changes are correlated with the level of infectivity. Of note, a dose-dependent increase in A-beta levels was also found in the cerebrospinal fluid of mice inoculated with these infected clones. By demonstrating that pathogenic prions trigger increases in A-beta levels through the deviation of PrPC signaling, our data argue that A-beta may exacerbate prion-induced toxicity.
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Affiliation(s)
- E Pradines
- Cellules Souches, Signalisation et Prions, INSERM UMR-S747, 75006, Paris, France
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22
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A brain aggregate model gives new insights into the pathobiology and treatment of prion diseases. J Neuropathol Exp Neurol 2012; 71:449-66. [PMID: 22507918 DOI: 10.1097/nen.0b013e3182544680] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Brain aggregates (BrnAggs) derived from fetal mouse brains contain mature neurons and glial cells. We determined that BrnAggs are consistently infected with Rocky Mountain Laboratory scrapie strain prions and produce increasing levels of the pathogenic form of the prion protein (PrP). Their abundant dendrites undergo degeneration shortly after prion infection. Treatment of prion-infected BrnAggs with drugs, such as a γ-secretase inhibitors and quinacrine (Qa), which stop PrP formation and dendritic degeneration, mirrors the results from rodent studies. Because PrP is trafficked into lysosomes by endocytosis and autophagosomes by phagocytosis in neurons of prion strain-infected BrnAggs, we studied the effects of drugs that modulate subcellular trafficking. Rapamycin (Rap), which activates autophagy, markedly increased light-chain 3-II (LC3-II)-positive autophagosomes and cathepsin D-positive lysosomes in BrnAggs but could not eliminate the intracellular PrP within them. Adding Qa to Rap markedly reduced the number of LC3-II-positive autolysosomes. Rap + Qa created a competition between Rap increasing and Qa decreasing LC3-II. Rapamycin + Qa decreased total PrP by 56% compared with that of Qa alone, which reduced PrP by 37% relative to Rap alone. We conclude that the decrease was dominated by the ability of Qa to decrease the formation of PrP. Therefore, BrnAggs provide an efficient in vitro tool for screening drug therapies and studying the complex biology of prions.
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Herva ME, Weissman C. Cell-specific susceptibility to prion strains is a property of the intact cell. Prion 2012; 6:371-4. [PMID: 22561192 DOI: 10.4161/pri.20198] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Prions consist of PrP (Sc), a misfolded version of the cellular protein PrP (C). They occur in a variety of strains that share the amino acid sequence of PrP but differ in phenotypic properties, such as cell tropism and pathogenicity; strain-ness is attributed to the conformation of PrP (Sc). To gain insight as to how susceptibility of cells to a given prion strain comes about, we compared amplification of RML prions by PMCA, using cell lysates from related, RML-resistant and RML-susceptible cell lines as substrate. We found that both lysates supported amplification of RML PrP (Sc) equally well, despite a 280-fold difference in the susceptibility of the cells from which they were derived. Thus, susceptibility is an attribute of the intact cell.
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Affiliation(s)
- Maria E Herva
- Department of Infectology, Scripps Florida, Jupiter, FL, USA
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Relaño-Ginés A, Lehmann S, Bencsik A, Herva ME, Torres JM, Crozet CA. Stem Cell Therapy Extends Incubation and Survival Time in Prion-Infected Mice in a Time Window–Dependant Manner. J Infect Dis 2011; 204:1038-45. [DOI: 10.1093/infdis/jir484] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Haigh CL, McGlade AR, Lewis V, Masters CL, Lawson VA, Collins SJ. Acute exposure to prion infection induces transient oxidative stress progressing to be cumulatively deleterious with chronic propagation in vitro. Free Radic Biol Med 2011; 51:594-608. [PMID: 21466851 DOI: 10.1016/j.freeradbiomed.2011.03.035] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2010] [Revised: 03/03/2011] [Accepted: 03/28/2011] [Indexed: 01/01/2023]
Abstract
Neuronal loss is a pathological feature of prion diseases for which increased reactive oxygen species (ROS) and consequent oxidative stress is one proposed mechanism. The processes underlying ROS production in prion disease and the precise relationship to misfolding of the prion protein remain obscure. Using cell culture models of prion infection we found that cells demonstrate a rapid, prion protein (PrP) dependent, increase in intracellular ROS following exposure to infectious inoculum. ROS production correlated with internalisation and increased intracellular protease resistant PrP (PrP(Res)). The ROS increase was predominantly lysosomal in origin but not sustained, with cells adapting within 48 hours. Overall ROS levels remained normal in the chronically prion infected cell population; however a subpopulation characterised by loss of membrane phosphatidylserine asymmetry exhibited highly peroxidised intracellular aggregates that localised with PrP and intense caspase activation. These apoptotic cells showed increased ROS closely correlating with increased PrP(Res). Our findings demonstrate that a PrP-dependent, transient, increase in intracellular ROS is characteristic of acute cellular prion infection, while chronic phases of prion infection in vitro are associated with a significant subpopulation manifesting apoptosis accompanying heightened oxidative stress and increased PrP(Res) burden. Such observations strengthen the direct links between heightened ROS and ongoing prion propagation with eventual cellular demise.
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Affiliation(s)
- Cathryn L Haigh
- Department of Pathology, The University of Melbourne, Parkville, 3010, Australia
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