1
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Cembran A, Fernandez-Funez P. Intrinsic determinants of prion protein neurotoxicity in Drosophila: from sequence to (dys)function. Front Mol Neurosci 2023; 16:1231079. [PMID: 37645703 PMCID: PMC10461008 DOI: 10.3389/fnmol.2023.1231079] [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: 06/23/2023] [Accepted: 08/02/2023] [Indexed: 08/31/2023] Open
Abstract
Prion diseases are fatal brain disorders characterized by deposition of insoluble isoforms of the prion protein (PrP). The normal and pathogenic structures of PrP are relatively well known after decades of studies. Yet our current understanding of the intrinsic determinants regulating PrP misfolding are largely missing. A 3D subdomain of PrP comprising the β2-α2 loop and helix 3 contains high sequence and structural variability among animals and has been proposed as a key domain regulating PrP misfolding. We combined in vivo work in Drosophila with molecular dynamics (MD) simulations, which provide additional insight to assess the impact of candidate substitutions in PrP from conformational dynamics. MD simulations revealed that in human PrP WT the β2-α2 loop explores multiple β-turn conformations, whereas the Y225A (rabbit PrP-like) substitution strongly favors a 310-turn conformation, a short right-handed helix. This shift in conformational diversity correlates with lower neurotoxicity in flies. We have identified additional conformational features and candidate amino acids regulating the high toxicity of human PrP and propose a new strategy for testing candidate modifiers first in MD simulations followed by functional experiments in flies. In this review we expand on these new results to provide additional insight into the structural and functional biology of PrP through the prism of the conformational dynamics of a 3D domain in the C-terminus. We propose that the conformational dynamics of this domain is a sensitive measure of the propensity of PrP to misfold and cause toxicity. This provides renewed opportunities to identify the intrinsic determinants of PrP misfolding through the contribution of key amino acids to different conformational states by MD simulations followed by experimental validation in transgenic flies.
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Affiliation(s)
- Alessandro Cembran
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN, United States
| | - Pedro Fernandez-Funez
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, United States
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2
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Avar M, Heinzer D, Thackray AM, Liu Y, Hruska‐Plochan M, Sellitto S, Schaper E, Pease DP, Yin J, Lakkaraju AKK, Emmenegger M, Losa M, Chincisan A, Hornemann S, Polymenidou M, Bujdoso R, Aguzzi A. An arrayed genome-wide perturbation screen identifies the ribonucleoprotein Hnrnpk as rate-limiting for prion propagation. EMBO J 2022; 41:e112338. [PMID: 36254605 PMCID: PMC9713719 DOI: 10.15252/embj.2022112338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/17/2022] [Accepted: 09/22/2022] [Indexed: 01/15/2023] Open
Abstract
A defining characteristic of mammalian prions is their capacity for self-sustained propagation. Theoretical considerations and experimental evidence suggest that prion propagation is modulated by cell-autonomous and non-autonomous modifiers. Using a novel quantitative phospholipase protection assay (QUIPPER) for high-throughput prion measurements, we performed an arrayed genome-wide RNA interference (RNAi) screen aimed at detecting cellular host-factors that can modify prion propagation. We exposed prion-infected cells in high-density microplates to 35,364 ternary pools of 52,746 siRNAs targeting 17,582 genes representing the majority of the mouse protein-coding transcriptome. We identified 1,191 modulators of prion propagation. While 1,151 modified the expression of both the pathological prion protein, PrPSc , and its cellular counterpart, PrPC , 40 genes selectively affected PrPSc . Of the latter 40 genes, 20 augmented prion production when suppressed. A prominent limiter of prion propagation was the heterogeneous nuclear ribonucleoprotein Hnrnpk. Psammaplysene A (PSA), which binds Hnrnpk, reduced prion levels in cultured cells and protected them from cytotoxicity. PSA also reduced prion levels in infected cerebellar organotypic slices and alleviated locomotor deficits in prion-infected Drosophila melanogaster expressing ovine PrPC . Hence, genome-wide QUIPPER-based perturbations can discover actionable cellular pathways involved in prion propagation. Further, the unexpected identification of a prion-controlling ribonucleoprotein suggests a role for RNA in the generation of infectious prions.
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Affiliation(s)
- Merve Avar
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Daniel Heinzer
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Alana M Thackray
- Department of Veterinary MedicineUniversity of CambridgeCambridgeUK
| | - Yingjun Liu
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | | | - Stefano Sellitto
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Elke Schaper
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Daniel P Pease
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Jiang‐An Yin
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | | | - Marc Emmenegger
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Marco Losa
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Andra Chincisan
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Simone Hornemann
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | | | - Raymond Bujdoso
- Department of Veterinary MedicineUniversity of CambridgeCambridgeUK
| | - Adriano Aguzzi
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
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3
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Thackray AM, Lam B, McNulty EE, Nalls AV, Mathiason CK, Magadi SS, Jackson WS, Andréoletti O, Marrero-Winkens C, Schätzl H, Bujdoso R. Clearance of variant Creutzfeldt-Jakob disease prions in vivo by the Hsp70 disaggregase system. Brain 2022; 145:3236-3249. [PMID: 35446941 PMCID: PMC9473358 DOI: 10.1093/brain/awac144] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 03/10/2022] [Accepted: 03/30/2022] [Indexed: 11/13/2022] Open
Abstract
The metazoan Hsp70 disaggregase protects neurons from proteotoxicity that arises from the accumulation of misfolded protein aggregates. Hsp70 and its co-chaperones disassemble and extract polypeptides from protein aggregates for refolding or degradation. The effectiveness of the chaperone system decreases with age and leads to accumulation rather than removal of neurotoxic protein aggregates. Therapeutic enhancement of the Hsp70 protein disassembly machinery is proposed to counter late-onset protein misfolding neurodegenerative disease that may arise. In the context of prion disease, it is not known whether stimulation of protein aggregate disassembly paradoxically leads to enhanced formation of seeding competent species of disease-specific proteins and acceleration of neurodegenerative disease. Here we have tested the hypothesis that modulation of Hsp70 disaggregase activity perturbs mammalian prion-induced neurotoxicity and prion seeding activity. To do so we used prion protein (PrP) transgenic Drosophila that authentically replicate mammalian prions. RNASeq identified that Hsp70, DnaJ-1 and Hsp110 gene expression was downregulated in prion-exposed PrP Drosophila. We demonstrated that RNAi knockdown of Hsp110 or DnaJ-1 gene expression in variant Creutzfeldt–Jakob disease prion-exposed human PrP Drosophila enhanced neurotoxicity, whereas overexpression mitigated toxicity. Strikingly, prion seeding activity in variant Creutzfeldt–Jakob disease prion-exposed human PrP Drosophila was ablated or reduced by Hsp110 or DnaJ-1 overexpression, respectively. Similar effects were seen in scrapie prion-exposed ovine PrP Drosophila with modified Hsp110 or DnaJ-1 gene expression. These unique observations show that the metazoan Hsp70 disaggregase facilitates the clearance of mammalian prions and that its enhanced activity is a potential therapeutic strategy for human prion disease.
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Affiliation(s)
- Alana M Thackray
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK
| | - Brian Lam
- Medical Research Council Metabolic Diseases Unit, Wellcome-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Erin E McNulty
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Amy V Nalls
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Candace K Mathiason
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Srivathsa Subramanya Magadi
- Wallenberg Center for Molecular Medicine, Department of Clinical and Experimental Medicine, Linköping University, 581 83 Linköping, Sweden
| | - Walker S Jackson
- Wallenberg Center for Molecular Medicine, Department of Clinical and Experimental Medicine, Linköping University, 581 83 Linköping, Sweden
| | - Olivier Andréoletti
- UMR INRA ENVT 1225 -Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, 31076 Toulouse, France
| | - Cristóbal Marrero-Winkens
- Calgary Prion Research Unit, Faculty of Veterinary Medicine, University of Calgary TRW 2D10, 3280 Hospital Drive NW, Calgary, AB, Canada T2N 4Z6
| | - Hermann Schätzl
- Calgary Prion Research Unit, Faculty of Veterinary Medicine, University of Calgary TRW 2D10, 3280 Hospital Drive NW, Calgary, AB, Canada T2N 4Z6
| | - Raymond Bujdoso
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK
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Myers RR, Sanchez-Garcia J, Leving DC, Melvin RG, Fernandez-Funez P. New Drosophila models to uncover the intrinsic and extrinsic factors that mediate the toxicity of the human prion protein. Dis Model Mech 2022; 15:dmm049184. [PMID: 35142350 PMCID: PMC9093039 DOI: 10.1242/dmm.049184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 02/01/2022] [Indexed: 11/20/2022] Open
Abstract
Misfolding of the prion protein (PrP) is responsible for devastating neurological disorders in humans and other mammals. An unresolved problem in the field is unraveling the mechanisms governing PrP conformational dynamics, misfolding, and the cellular mechanism leading to neurodegeneration. The variable susceptibility of mammals to prion diseases is a natural resource that can be exploited to understand the conformational dynamics of PrP. Here we present a new fly model expressing human PrP with new, robust phenotypes in brain neurons and the eye. By using comparable attP2 insertions, we demonstrated the heightened toxicity of human PrP compared to rodent PrP along with a specific interaction with the amyloid-β peptide. By using this new model, we started to uncover the intrinsic (sequence/structure) and extrinsic (interactions) factors regulating PrP toxicity. We described PERK (officially known as EIF2AK3 in humans) and activating transcription factor 4 (ATF4) as key in the cellular mechanism mediating the toxicity of human PrP and uncover a key new protective activity for 4E-BP (officially known as Thor in Drosophila and EIF4EBP2 in humans), an ATF4 transcriptional target. Lastly, mutations in human PrP (N159D, D167S, N174S) showed partial protective activity, revealing its high propensity to misfold into toxic conformations.
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Affiliation(s)
- Ryan R. Myers
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, Duluth, MN 55812, USA
| | | | - Daniel C. Leving
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, Duluth, MN 55812, USA
| | - Richard G. Melvin
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, Duluth, MN 55812, USA
| | - Pedro Fernandez-Funez
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, Duluth, MN 55812, USA
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5
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Bujdoso R, Smith A, Fleck O, Spiropoulos J, Andréoletti O, Thackray AM. Prion disease modelled in Drosophila. Cell Tissue Res 2022; 392:47-62. [PMID: 35092497 PMCID: PMC10113284 DOI: 10.1007/s00441-022-03586-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 01/17/2022] [Indexed: 11/02/2022]
Abstract
AbstractPrion diseases are fatal neurodegenerative conditions of humans and various vertebrate species that are transmissible between individuals of the same or different species. A novel infectious moiety referred to as a prion is considered responsible for transmission of these conditions. Prion replication is believed to be the cause of the neurotoxicity that arises during prion disease pathogenesis. The prion hypothesis predicts that the transmissible prion agent consists of PrPSc, which is comprised of aggregated misfolded conformers of the normal host protein PrPC. It is important to understand the biology of transmissible prions and to identify genetic modifiers of prion-induced neurotoxicity. This information will underpin the development of therapeutic and control strategies for human and animal prion diseases. The most reliable method to detect prion infectivity is by in vivo transmission in a suitable experimental host, which to date have been mammalian species. Current prion bioassays are slow, cumbersome and relatively insensitive to low titres of prion infectivity, and do not lend themselves to rapid genetic analysis of prion disease. Here, we provide an overview of our novel studies that have led to the establishment of Drosophila melanogaster, a genetically well-defined invertebrate host, as a sensitive, versatile and economically viable animal model for the detection of mammalian prion infectivity and genetic modifiers of prion-induced toxicity.
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6
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Transcriptional signature of prion-induced neurotoxicity in a Drosophila model of transmissible mammalian prion disease. Biochem J 2020; 477:833-852. [PMID: 32108870 PMCID: PMC7054746 DOI: 10.1042/bcj20190872] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/14/2020] [Accepted: 01/31/2020] [Indexed: 12/11/2022]
Abstract
Prion diseases are fatal transmissible neurodegenerative conditions of humans and animals that arise through neurotoxicity induced by PrP misfolding. The cellular and molecular mechanisms of prion-induced neurotoxicity remain undefined. Understanding these processes will underpin therapeutic and control strategies for human and animal prion diseases, respectively. Prion diseases are difficult to study in their natural hosts and require the use of tractable animal models. Here we used RNA-Seq-based transcriptome analysis of prion-exposed Drosophila to probe the mechanism of prion-induced neurotoxicity. Adult Drosophila transgenic for pan neuronal expression of ovine PrP targeted to the plasma membrane exhibit a neurotoxic phenotype evidenced by decreased locomotor activity after exposure to ovine prions at the larval stage. Pathway analysis and quantitative PCR of genes differentially expressed in prion-infected Drosophila revealed up-regulation of cell cycle activity and DNA damage response, followed by down-regulation of eIF2 and mTOR signalling. Mitochondrial dysfunction was identified as the principal toxicity pathway in prion-exposed PrP transgenic Drosophila. The transcriptomic changes we observed were specific to PrP targeted to the plasma membrane since these prion-induced gene expression changes were not evident in similarly treated Drosophila transgenic for cytosolic pan neuronal PrP expression, or in non-transgenic control flies. Collectively, our data indicate that aberrant cell cycle activity, repression of protein synthesis and altered mitochondrial function are key events involved in prion-induced neurotoxicity, and correlate with those identified in mammalian hosts undergoing prion disease. These studies highlight the use of PrP transgenic Drosophila as a genetically well-defined tractable host to study mammalian prion biology.
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7
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Thackray AM, Andréoletti O, Bujdoso R. Mammalian prion propagation in PrP transgenic Drosophila. Brain 2019; 141:2700-2710. [PMID: 29985975 PMCID: PMC6113635 DOI: 10.1093/brain/awy183] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/24/2018] [Indexed: 12/22/2022] Open
Abstract
Mammalian prions propagate by template-directed misfolding and aggregation of normal cellular prion related protein PrPC as it converts into disease-associated conformers collectively referred to as PrPSc. Mammalian species may be permissive for prion disease because these hosts have co-evolved specific co-factors that assist PrPC conformational change and prion propagation. We have tested this hypothesis by examining whether faithful prion propagation occurs in the normally PrPC-null invertebrate host Drosophila melanogaster. Ovine PrP transgenic Drosophila exposed at the larval stage to ovine scrapie showed a progressive accumulation of transmissible prions in adult flies. Strikingly, the biological properties of distinct ovine prion strains were maintained during their propagation in Drosophila. Our observations show that the co-factors necessary for strain-specific prion propagation are not unique to mammalian species. Our studies establish Drosophila as a novel host for the study of transmissible mammalian prions.
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Affiliation(s)
- Alana M Thackray
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 OES, UK
| | - Olivier Andréoletti
- UMR INRA ENVT 1225 -Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, Toulouse, France
| | - Raymond Bujdoso
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 OES, UK
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8
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Vorberg I, Chiesa R. Experimental models to study prion disease pathogenesis and identify potential therapeutic compounds. Curr Opin Pharmacol 2019; 44:28-38. [PMID: 30878006 DOI: 10.1016/j.coph.2019.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/13/2019] [Accepted: 02/13/2019] [Indexed: 01/02/2023]
Abstract
Prion diseases are devastating neurodegenerative disorders for which no drugs are available. The successful development of therapeutics depends on drug screening platforms and preclinical models that recapitulate key molecular and pathological features of the disease. Innovative experimental tools have been developed over the last few years that might facilitate drug discovery, including cell-free prion replication assays and prion-infected flies. However, there is still room for improvement. Animal models of genetic prion disease are few, and only partially recapitulate the complexity of the human disorder. Moreover, we still lack a human cell culture model suitable for high-content anti-prion drug screening. This review provides an overview of the models currently used in prion research, and discusses their promise and limitations for drug discovery.
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Affiliation(s)
- Ina Vorberg
- German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany; Rheinische Friedrich-Wilhelms-Universität Bonn, 53127 Bonn, Germany.
| | - Roberto Chiesa
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, 20156 Milan, Italy.
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9
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Younan ND, Chen KF, Rose RS, Crowther DC, Viles JH. Prion protein stabilizes amyloid-β (Aβ) oligomers and enhances Aβ neurotoxicity in a Drosophila model of Alzheimer's disease. J Biol Chem 2018; 293:13090-13099. [PMID: 29887525 DOI: 10.1074/jbc.ra118.003319] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/05/2018] [Indexed: 12/16/2022] Open
Abstract
The cellular prion protein (PrPC) can act as a cell-surface receptor for β-amyloid (Aβ) peptide; however, a role for PrPC in the pathogenesis of Alzheimer's disease (AD) is contested. Here, we expressed a range of Aβ isoforms and PrPC in the Drosophila brain. We found that co-expression of Aβ and PrPC significantly reduces the lifespan, disrupts circadian rhythms, and increases Aβ deposition in the fly brain. In contrast, under the same conditions, expression of Aβ or PrPC individually did not lead to these phenotypic changes. In vitro studies revealed that substoichiometric amounts of PrPC trap Aβ as oligomeric assemblies and fragment-preformed Aβ fibers. The ability of membrane-anchored PrPC to trap Aβ as cytotoxic oligomers at the membrane surface and fragment inert Aβ fibers suggests a mechanism by which PrPC exacerbates Aβ deposition and pathogenic phenotypes in the fly, supporting a role for PrPC in AD. This study provides a second animal model linking PrPC expression with Aβ toxicity and supports a role for PrPC in AD pathogenesis. Blocking the interaction of Aβ and PrPC represents a potential therapeutic strategy.
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Affiliation(s)
- Nadine D Younan
- From the School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, United Kingdom
| | - Ko-Fan Chen
- the Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London WC1N 3BG, United Kingdom, and
| | - Ruth-Sarah Rose
- From the School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, United Kingdom
| | - Damian C Crowther
- the Neuroscience IMED Biotech Unit, AstraZeneca, Cambridge CB21 6GH, United Kingdom
| | - John H Viles
- From the School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, United Kingdom,
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Thackray AM, Andréoletti O, Bujdoso R. The use of PrP transgenic Drosophila to replace and reduce vertebrate hosts in the bioassay of mammalian prion infectivity. F1000Res 2018; 7:595. [PMID: 29946445 PMCID: PMC5998032 DOI: 10.12688/f1000research.14753.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/27/2018] [Indexed: 11/24/2022] Open
Abstract
Prion diseases are fatal neurodegenerative conditions of humans and vertebrate species. The transmissible prion agent is a novel infectious particle composed principally of PrP Sc, an abnormal isomer of the normal host protein PrP C. The only reliable method to detect mammalian prion infectivity is by bioassay, invariably in a vertebrate host. The current prion bioassays typically involve intracerebral or peripheral inoculation of test material into the experimental host and subsequent euthanasia when clinical signs of terminal prion disease become evident. It may be months or years before the onset of clinical disease becomes evident and a pre-determined clinical end-point is reached. Consequently, bioassay of prion infectivity in vertebrate species is cumbersome, time consuming, expensive, and increasingly open to ethical debate because these animals are subjected to terminal neurodegenerative disease. Prions are a significant risk to public health through the potential for zoonotic transmission of animal prion diseases. Attention has focussed on the measurement of prion infectivity in different tissues and blood from prion-infected individuals in order to determine the distribution of infectious prions in diseased hosts. New animal models are required in order to replace or reduce, where possible, the dependency on the use of vertebrate species, including the 'gold standard' mouse prion bioassay, to assess prion infectivity levels. Here we highlight the development of a Drosophila-based prion bioassay, a highly sensitive and rapid invertebrate animal system that can efficiently detect mammalian prions. This novel invertebrate model system will be of considerable interest to biologists who perform prion bioassays as it will promote reduction and replacement in the number of sentient animals currently used for this purpose. This article is a composite of previous methods that provides an overview of the methodology of the model and discusses the experimental data to promote its viability for use instead of more sentient hosts.
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Affiliation(s)
- Alana M. Thackray
- Department of Veterinary Medicine, University of Cambridge, Cambridge, CB3 OES, UK
| | - Olivier Andréoletti
- UMR INRA ENVT 1225 -Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, Toulouse, 31076, France
| | - Raymond Bujdoso
- Department of Veterinary Medicine, University of Cambridge, Cambridge, CB3 OES, UK
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11
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Fraqueza MJR, Patarata LADSC. Constraints of HACCP Application on Edible Insect for Food and Feed. FUTURE FOODS 2017. [DOI: 10.5772/intechopen.69300] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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12
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Genetic human prion disease modelled in PrP transgenic Drosophila. Biochem J 2017; 474:3253-3267. [PMID: 28814578 PMCID: PMC5606059 DOI: 10.1042/bcj20170462] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/07/2017] [Accepted: 08/15/2017] [Indexed: 12/26/2022]
Abstract
Inherited human prion diseases, such as fatal familial insomnia (FFI) and familial Creutzfeldt–Jakob disease (fCJD), are associated with autosomal dominant mutations in the human prion protein gene PRNP and accumulation of PrPSc, an abnormal isomer of the normal host protein PrPC, in the brain of affected individuals. PrPSc is the principal component of the transmissible neurotoxic prion agent. It is important to identify molecular pathways and cellular processes that regulate prion formation and prion-induced neurotoxicity. This will allow identification of possible therapeutic interventions for individuals with, or at risk from, genetic human prion disease. Increasingly, Drosophila has been used to model human neurodegenerative disease. An important unanswered question is whether genetic prion disease with concomitant spontaneous prion formation can be modelled in Drosophila. We have used pUAST/PhiC31-mediated site-directed mutagenesis to generate Drosophila transgenic for murine or hamster PrP (prion protein) that carry single-codon mutations associated with genetic human prion disease. Mouse or hamster PrP harbouring an FFI (D178N) or fCJD (E200K) mutation showed mild Proteinase K resistance when expressed in Drosophila. Adult Drosophila transgenic for FFI or fCJD variants of mouse or hamster PrP displayed a spontaneous decline in locomotor ability that increased in severity as the flies aged. Significantly, this mutant PrP-mediated neurotoxic fly phenotype was transferable to recipient Drosophila that expressed the wild-type form of the transgene. Collectively, our novel data are indicative of the spontaneous formation of a PrP-dependent neurotoxic phenotype in FFI- or CJD-PrP transgenic Drosophila and show that inherited human prion disease can be modelled in this invertebrate host.
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13
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Fernandez-Funez P, Sanchez-Garcia J, Rincon-Limas DE. Drosophila models of prionopathies: insight into prion protein function, transmission, and neurotoxicity. Curr Opin Genet Dev 2017; 44:141-148. [PMID: 28415023 PMCID: PMC5474952 DOI: 10.1016/j.gde.2017.03.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 02/03/2017] [Accepted: 03/21/2017] [Indexed: 11/26/2022]
Abstract
Prion diseases (PrD) are unique neurodegenerative conditions with sporadic, genetic, and infectious etiologies. The agent responsible for these pathologies is a misfolded conformation of the prion protein (PrP). Although a process of autocatalytic "conversion" is known to mediate disease transmission, important gaps still remain regarding the physiological function of PrP and its relevance to pathogenesis, the molecular and cellular mechanisms mediating neurotoxicity and transmission, and the PrP conformations responsible for neurotoxicity. New Drosophila models expressing mammalian PrP have revealed physiological insight into PrP function and opened the door to significant progress in prion transmission and PrP neurotoxicity. Importantly, flies expressing human PrP showing a robust eye phenotype will allow performing genetic screens to uncover novel mechanisms mediating PrP neurotoxicity.
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Affiliation(s)
- Pedro Fernandez-Funez
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, Duluth, MN 55811, USA.
| | - Jonatan Sanchez-Garcia
- Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Diego E Rincon-Limas
- Departments of Neurology and Neuroscience, McKnight Brain Institute and Center for Translational Research on Neurodegenerative Diseases, University of Florida, Gainesville, FL 32611, USA
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14
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Bioassay of prion-infected blood plasma in PrP transgenic Drosophila. Biochem J 2016; 473:4399-4412. [PMID: 27733649 DOI: 10.1042/bcj20160417] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 10/03/2016] [Accepted: 10/11/2016] [Indexed: 01/27/2023]
Abstract
In pursuit of a tractable bioassay to assess blood prion infectivity, we have generated prion protein (PrP) transgenic Drosophila, which show a neurotoxic phenotype in adulthood after exposure to exogenous prions at the larval stage. Here, we determined the sensitivity of ovine PrP transgenic Drosophila to ovine prion infectivity by exposure of these flies to a dilution series of scrapie-infected sheep brain homogenate. Ovine PrP transgenic Drosophila showed a significant neurotoxic response to dilutions of 10-2 to 10-10 of the original scrapie-infected sheep brain homogenate. Significantly, we determined that this prion-induced neurotoxic response in ovine PrP transgenic Drosophila was transmissible to ovine PrP transgenic mice, which is indicative of authentic mammalian prion detection by these flies. As a consequence, we considered that PrP transgenic Drosophila were sufficiently sensitive to exogenous mammalian prions to be capable of detecting prion infectivity in the blood of scrapie-infected sheep. To test this hypothesis, we exposed ovine PrP transgenic Drosophila to scrapie-infected plasma, a blood fraction notoriously difficult to assess by conventional prion bioassays. Notably, pre-clinical plasma from scrapie-infected sheep induced neurotoxicity in PrP transgenic Drosophila and this effect was more pronounced after exposure to samples collected at the clinical phase of disease. The neurotoxic phenotype in ovine PrP transgenic Drosophila induced by plasma from scrapie-infected sheep was transmissible since head homogenate from these flies caused neurotoxicity in recipient flies during fly-to-fly transmission. Our data show that PrP transgenic Drosophila can be used successfully to bioassay prion infectivity in blood from a prion-diseased mammalian host.
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Bujdoso R, Landgraf M, Jackson WS, Thackray AM. Prion-induced neurotoxicity: Possible role for cell cycle activity and DNA damage response. World J Virol 2015; 4:188-197. [PMID: 26279981 PMCID: PMC4534811 DOI: 10.5501/wjv.v4.i3.188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 03/19/2015] [Accepted: 04/30/2015] [Indexed: 02/05/2023] Open
Abstract
Protein misfolding neurodegenerative diseases arise through neurotoxicity induced by aggregation of host proteins. These conditions include Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, motor neuron disease, tauopathies and prion diseases. Collectively, these conditions are a challenge to society because of the increasing aged population and through the real threat to human food security by animal prion diseases. It is therefore important to understand the cellular and molecular mechanisms that underlie protein misfolding-induced neurotoxicity as this will form the basis for designing strategies to alleviate their burden. Prion diseases are an important paradigm for neurodegenerative conditions in general since several of these maladies have now been shown to display prion-like phenomena. Increasingly, cell cycle activity and the DNA damage response are recognised as cellular events that participate in the neurotoxic process of various neurodegenerative diseases, and their associated animal models, which suggests they are truly involved in the pathogenic process and are not merely epiphenomena. Here we review the role of cell cycle activity and the DNA damage response in neurodegeneration associated with protein misfolding diseases, and suggest that these events contribute towards prion-induced neurotoxicity. In doing so, we highlight PrP transgenic Drosophila as a tractable model for the genetic analysis of transmissible mammalian prion disease.
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Fernández-Borges N, Eraña H, Venegas V, Elezgarai SR, Harrathi C, Castilla J. Animal models for prion-like diseases. Virus Res 2015; 207:5-24. [PMID: 25907990 DOI: 10.1016/j.virusres.2015.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/08/2015] [Accepted: 04/10/2015] [Indexed: 12/13/2022]
Abstract
Prion diseases or Transmissible Spongiform Encephalopathies (TSEs) are a group of fatal neurodegenerative disorders affecting several mammalian species being Creutzfeldt-Jacob Disease (CJD) the most representative in human beings, scrapie in ovine, Bovine Spongiform Encephalopathy (BSE) in bovine and Chronic Wasting Disease (CWD) in cervids. As stated by the "protein-only hypothesis", the causal agent of TSEs is a self-propagating aberrant form of the prion protein (PrP) that through a misfolding event acquires a β-sheet rich conformation known as PrP(Sc) (from scrapie). This isoform is neurotoxic, aggregation prone and induces misfolding of native cellular PrP. Compelling evidence indicates that disease-specific protein misfolding in amyloid deposits could be shared by other disorders showing aberrant protein aggregates such as Alzheimer's Disease (AD), Parkinson's Disease (PD), Amyotrophic lateral sclerosis (ALS) and systemic Amyloid A amyloidosis (AA amyloidosis). Evidences of shared mechanisms of the proteins related to each disease with prions will be reviewed through the available in vivo models. Taking prion research as reference, typical prion-like features such as seeding and propagation ability, neurotoxic species causing disease, infectivity, transmission barrier and strain evidences will be analyzed for other protein-related diseases. Thus, prion-like features of amyloid β peptide and tau present in AD, α-synuclein in PD, SOD-1, TDP-43 and others in ALS and serum α-amyloid (SAA) in systemic AA amyloidosis will be reviewed through models available for each disease.
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Affiliation(s)
| | - Hasier Eraña
- CIC bioGUNE, Parque tecnológico de Bizkaia, Derio 48160, Bizkaia, Spain
| | - Vanesa Venegas
- CIC bioGUNE, Parque tecnológico de Bizkaia, Derio 48160, Bizkaia, Spain
| | - Saioa R Elezgarai
- CIC bioGUNE, Parque tecnológico de Bizkaia, Derio 48160, Bizkaia, Spain
| | - Chafik Harrathi
- CIC bioGUNE, Parque tecnológico de Bizkaia, Derio 48160, Bizkaia, Spain
| | - Joaquín Castilla
- CIC bioGUNE, Parque tecnológico de Bizkaia, Derio 48160, Bizkaia, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao 48013, Bizkaia, Spain.
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