1
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Johansson L, Reyes JF, Ali T, Schätzl H, Gilch S, Hallbeck M. Lack of cellular prion protein causes Amyloid β accumulation, increased extracellular vesicle abundance, and changes to exosome biogenesis proteins. Mol Cell Biochem 2024:10.1007/s11010-024-05059-0. [PMID: 38970706 DOI: 10.1007/s11010-024-05059-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Accepted: 06/29/2024] [Indexed: 07/08/2024]
Abstract
Alzheimer's disease (AD) progression is closely linked to the propagation of pathological Amyloid β (Aβ), a process increasingly understood to involve extracellular vesicles (EVs), namely exosomes. The specifics of Aβ packaging into exosomes remain elusive, although evidence suggests an ESCRT (Endosomal Sorting Complex Required for Transport)-independent origin to be responsible in spreading of AD pathogenesis. Intriguingly, PrPC, known to influence exosome abundance and bind oligomeric Aβ (oAβ), can be released in exosomes via both ESCRT-dependent and ESCRT-independent pathways, raising questions about its role in oAβ trafficking. Thus, we quantified Aβ levels within EVs, cell medium, and intracellularly, alongside exosome biogenesis-related proteins, following deletion or overexpression of PrPC. The same parameters were also evaluated in the presence of specific exosome inhibitors, namely Manumycin A and GW4869. Our results revealed that deletion of PrPC increases intracellular Aβ accumulation and amplifies EV abundance, alongside significant changes in cellular levels of exosome biogenesis-related proteins Vps25, Chmp2a, and Rab31. In contrast, cellular expression of PrPC did not alter exosomal Aβ levels. This highlights PrPC's influence on exosome biogenesis, albeit not in direct Aβ packaging. Additionally, our data confirm the ESCRT-independent exosome release of Aβ and we show a direct reduction in Chmp2a levels upon oAβ challenge. Furthermore, inhibition of opposite exosome biogenesis pathway resulted in opposite cellular PrPC levels. In conclusion, our findings highlight the intricate relationship between PrPC, exosome biogenesis, and Aβ release. Specifically, they underscore PrPC's critical role in modulating exosome-associated proteins, EV abundance, and cellular Aβ levels, thereby reinforcing its involvement in AD pathogenesis.
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Affiliation(s)
- Lovisa Johansson
- Department of Biomedical and Clinical Sciences and Department of Clinical Pathology, Linköping University, Linköping, Sweden.
| | - Juan F Reyes
- Department of Biomedical and Clinical Sciences and Department of Clinical Pathology, Linköping University, Linköping, Sweden
| | - Tahir Ali
- Calgary Prion Research Unit, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Hermann Schätzl
- Calgary Prion Research Unit, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Sabine Gilch
- Calgary Prion Research Unit, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Martin Hallbeck
- Department of Biomedical and Clinical Sciences and Department of Clinical Pathology, Linköping University, Linköping, Sweden.
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2
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Zheng X, Liu K, Xie Q, Xin H, Chen W, Lin S, Feng D, Zhu T. PHB2 Alleviates Neurotoxicity of Prion Peptide PrP 106-126 via PINK1/Parkin-Dependent Mitophagy. Int J Mol Sci 2023; 24:15919. [PMID: 37958902 PMCID: PMC10647768 DOI: 10.3390/ijms242115919] [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: 09/29/2023] [Revised: 10/29/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023] Open
Abstract
Prion diseases are a group of neurodegenerative diseases characterized by mitochondrial dysfunction and neuronal death. Mitophagy is a selective form of macroautophagy that clears injured mitochondria. Prohibitin 2 (PHB2) has been identified as a novel inner membrane mitophagy receptor that mediates mitophagy. However, the role of PHB2 in prion diseases remains unclear. In this study, we isolated primary cortical neurons from rats and used the neurotoxic prion peptide PrP106-126 as a cell model for prion diseases. We examined the role of PHB2 in PrP106-126-induced mitophagy using Western blotting and immunofluorescence microscopy and assessed the function of PHB2 in PrP106-126-induced neuronal death using the cell viability assay and the TUNEL assay. The results showed that PrP106-126 induced mitochondrial morphological abnormalities and mitophagy in primary cortical neurons. PHB2 was found to be indispensable for PrP106-126-induced mitophagy and was involved in the accumulation of PINK1 and recruitment of Parkin to mitochondria in primary neurons. Additionally, PHB2 depletion exacerbated neuronal cell death induced by PrP106-126, whereas the overexpression of PHB2 alleviated PrP106-126 neuronal toxicity. Taken together, this study demonstrated that PHB2 is indispensable for PINK1/Parkin-mediated mitophagy in PrP106-126-treated neurons and protects neurons against the neurotoxicity of the prion peptide.
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Affiliation(s)
- Xiaohui Zheng
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Kun Liu
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Qingqing Xie
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Hangkuo Xin
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wei Chen
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shengyu Lin
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Danqi Feng
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ting Zhu
- Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China (K.L.); (Q.X.)
- Key Laboratory of Animal Pathogen Infection and Immunology of Fujian Province, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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3
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Agamennone M, Storchi L, Marrone A, Paciotti R. Hampering the early aggregation of PrP-E200K protein by charge-based inhibitors: a computational study. J Comput Aided Mol Des 2021; 35:751-770. [PMID: 34110550 PMCID: PMC8213589 DOI: 10.1007/s10822-021-00393-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 06/04/2021] [Indexed: 11/25/2022]
Abstract
A multilayered computational workflow was designed to identify a druggable binding site on the surface of the E200K pathogenic mutant of the human prion protein, and to investigate the effect of the binding of small molecules in the inhibition of the early aggregation of this protein. At this purpose, we developed an efficient computational tool to scan the molecular interaction properties of a whole MD trajectory, thus leading to the characterization of plausible binding regions on the surface of PrP-E200K. These structural data were then employed to drive structure-based virtual screening and fragment-based approaches to the seeking of small molecular binders of the PrP-E200K. Six promising compounds were identified, and their binding stabilities were assessed by MD simulations. Therefore, analyses of the molecular electrostatic potential similarity between the bound complexes and unbound protein evidenced their potential activity as charged-based inhibitors of the PrP-E200K early aggregation.
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Affiliation(s)
| | - Loriano Storchi
- Department of Pharmacy, University "G d'Annunzio" of Chieti-Pescara, Chieti, Italy
- Molecular Discovery Limited, Middlesex, London, UK
| | - Alessandro Marrone
- Department of Pharmacy, University "G d'Annunzio" of Chieti-Pescara, Chieti, Italy
| | - Roberto Paciotti
- Department of Pharmacy, University "G d'Annunzio" of Chieti-Pescara, Chieti, Italy.
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4
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Oral administration of repurposed drug targeting Cyp46A1 increases survival times of prion infected mice. Acta Neuropathol Commun 2021; 9:58. [PMID: 33795005 PMCID: PMC8017635 DOI: 10.1186/s40478-021-01162-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 01/12/2023] Open
Abstract
Prion diseases are fatal, infectious, and incurable neurodegenerative disorders caused by misfolding of the cellular prion protein (PrPC) into the infectious isoform (PrPSc). In humans, there are sporadic, genetic and infectious etiologies, with sporadic Creutzfeldt-Jakob disease (sCJD) being the most common form. Currently, no treatment is available for prion diseases. Cellular cholesterol is known to impact prion conversion, which in turn results in an accumulation of cholesterol in prion-infected neurons. The major elimination of brain cholesterol is achieved by the brain specific enzyme, cholesterol 24-hydroxylase (CYP46A1). Cyp46A1 converts cholesterol into 24(S)-hydroxycholesterol, a membrane-permeable molecule that exits the brain. We have demonstrated for the first time that Cyp46A1 levels are reduced in the brains of prion-infected mice at advanced disease stage, in prion-infected neuronal cells and in post-mortem brains of sCJD patients. We have employed the Cyp46A1 activator efavirenz (EFV) for treatment of prion-infected neuronal cells and mice. EFV is an FDA approved anti-HIV medication effectively crossing the blood brain barrier and has been used for decades to chronically treat HIV patients. EFV significantly mitigated PrPSc propagation in prion-infected cells while preserving physiological PrPC and lipid raft integrity. Notably, oral administration of EFV treatment chronically at very low dosage starting weeks to months after intracerebral prion inoculation of mice significantly prolonged the lifespan of animals. In summary, our results suggest that Cyp46A1 as a novel therapeutic target and that its activation through repurposing the anti-retroviral medication EFV might be valuable treatment approach for prion diseases.
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5
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Hackl S, Ng XW, Lu D, Wohland T, Becker CFW. Cytoskeleton-dependent clustering of membrane-bound prion protein on the cell surface. J Biol Chem 2021; 296:100359. [PMID: 33539927 PMCID: PMC7988330 DOI: 10.1016/j.jbc.2021.100359] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 12/23/2022] Open
Abstract
Prion diseases are a group of neurodegenerative disorders that infect animals and humans with proteinaceous particles called prions. Prions consist of scrapie prion protein (PrPSc), a misfolded version of the cellular prion protein (PrPC). During disease progression, PrPSc replicates by interacting with PrPC and inducing its conversion to PrPSc. Attachment of PrPC to cellular membranes via a glycosylphosphatidylinositol (GPI) anchor is critical for the conversion of PrPC into PrPSc. However, the mechanisms governing PrPC conversion and replication on the membrane remain largely unclear. Here, a site-selectively modified PrP variant equipped with a fluorescent GPI anchor mimic (PrP-GPI) was employed to directly observe PrP at the cellular membrane in neuronal SH-SY5Y cells. PrP-GPI exhibits a cholesterol-dependent membrane accumulation and a cytoskeleton-dependent mobility. More specifically, inhibition of actin polymerization reduced the diffusion of PrP-GPI indicating protein clustering, which resembles the initial step of PrP aggregation and conversion into its pathogenic isoform. An intact actin cytoskeleton might therefore prevent conversion of PrPC into PrPSc and offer new therapeutic angles.
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Affiliation(s)
- Stefanie Hackl
- Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - Xue Wen Ng
- Departments of Biological Sciences and Chemistry and Centre for Bioimaging Sciences (CBIS), National University of Singapore (NUS), Singapore
| | - Danqin Lu
- Departments of Biological Sciences and Chemistry and Centre for Bioimaging Sciences (CBIS), National University of Singapore (NUS), Singapore; School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, China
| | - Thorsten Wohland
- Departments of Biological Sciences and Chemistry and Centre for Bioimaging Sciences (CBIS), National University of Singapore (NUS), Singapore
| | - Christian F W Becker
- Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria.
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6
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Mustazza C, Sbriccoli M, Minosi P, Raggi C. Small Molecules with Anti-Prion Activity. Curr Med Chem 2020; 27:5446-5479. [PMID: 31560283 DOI: 10.2174/0929867326666190927121744] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 08/08/2019] [Accepted: 09/05/2019] [Indexed: 01/20/2023]
Abstract
Prion pathologies are fatal neurodegenerative diseases caused by the misfolding of the physiological Prion Protein (PrPC) into a β-structure-rich isoform called PrPSc. To date, there is no available cure for prion diseases and just a few clinical trials have been carried out. The initial approach in the search of anti-prion agents had PrPSc as a target, but the existence of different prion strains arising from alternative conformations of PrPSc, limited the efficacy of the ligands to a straindependent ability. That has shifted research to PrPC ligands, which either act as chaperones, by stabilizing the native conformation, or inhibit its interaction with PrPSc. The role of transition-metal mediated oxidation processes in prion misfolding has also been investigated. Another promising approach is the indirect action via other cellular targets, like membrane domains or the Protein- Folding Activity of Ribosomes (PFAR). Also, new prion-specific high throughput screening techniques have been developed. However, so far no substance has been found to be able to extend satisfactorily survival time in animal models of prion diseases. This review describes the main features of the Structure-Activity Relationship (SAR) of the various chemical classes of anti-prion agents.
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Affiliation(s)
- Carlo Mustazza
- National Centre for Control and Evaluation of Medicines, Italian National Institute of Health, Viale Regina Elena 299, 00161 Rome, Italy
| | - Marco Sbriccoli
- Department of Neurosciences, Italian National Institute of Health, Viale Regina Elena 299, 00161 Rome, Italy
| | - Paola Minosi
- National Centre for Drug Research and Evaluation, Italian National Institute of Health, Viale Regina Elena 299, 00161 Rome, Italy
| | - Carla Raggi
- National Centre for Control and Evaluation of Medicines, Italian National Institute of Health, Viale Regina Elena 299, 00161 Rome, Italy
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7
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The Role of Vesicle Trafficking Defects in the Pathogenesis of Prion and Prion-Like Disorders. Int J Mol Sci 2020; 21:ijms21197016. [PMID: 32977678 PMCID: PMC7582986 DOI: 10.3390/ijms21197016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 11/26/2022] Open
Abstract
Prion diseases are fatal and transmissible neurodegenerative diseases in which the cellular form of the prion protein ‘PrPc’, misfolds into an infectious and aggregation prone isoform termed PrPSc, which is the primary component of prions. Many neurodegenerative diseases, like Alzheimer’s disease, Parkinson’s disease, and polyglutamine diseases, such as Huntington’s disease, are considered prion-like disorders because of the common characteristics in the propagation and spreading of misfolded proteins that they share with the prion diseases. Unlike prion diseases, these are non-infectious outside experimental settings. Many vesicular trafficking impairments, which are observed in prion and prion-like disorders, favor the accumulation of the pathogenic amyloid aggregates. In addition, many of the vesicular trafficking impairments that arise in these diseases, turn out to be further aggravating factors. This review offers an insight into the currently known vesicular trafficking defects in these neurodegenerative diseases and their implications on disease progression. These findings suggest that these impaired trafficking pathways may represent similar therapeutic targets in these classes of neurodegenerative disorders.
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Colini Baldeschi A, Vanni S, Zattoni M, Legname G. Novel regulators of PrP C expression as potential therapeutic targets in prion diseases. Expert Opin Ther Targets 2020; 24:759-776. [PMID: 32631090 DOI: 10.1080/14728222.2020.1782384] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Prion diseases are rare and fatal neurodegenerative disorders. The key molecular event in these disorders is the misfolding of the physiological form of the cellular prion protein, PrPC, leading to the accumulation of a pathological isoform, PrPSc, with unique features. Both isoforms share the same primary sequence, lacking detectable differences in posttranslational modification, a major hurdle for their biochemical or biophysical independent characterization. The mechanism underlying the conversion of PrPC to PrPSc is not completely understood, so finding an effective therapy to cure prion disorders is extremely challenging. AREAS COVERED This review discusses the strategies for decreasing prion replication and throws a spotlight on the relevance of PrPC in the prion accumulation process. EXPERT OPINION PrPC is the key substrate for prion pathology; hence, the most promising therapeutic approach appears to be the targeting of PrPC to block the production of the infectious isoform. The use of RNA interference and antisense oligonucleotide technologies may offer opportunities for treatment because of their success in clinical trials for other neurodegenerative diseases.
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Affiliation(s)
- Arianna Colini Baldeschi
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore Di Studi Avanzati (SISSA) , Trieste, Italy
| | - Silvia Vanni
- Osteoncology and Rare Tumors Center, Istituto Scientifico Romagnolo per Lo Studio E La Cura Dei Tumori (IRST) IRCCS , Meldola, Italy
| | - Marco Zattoni
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore Di Studi Avanzati (SISSA) , Trieste, Italy
| | - Giuseppe Legname
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore Di Studi Avanzati (SISSA) , Trieste, Italy
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9
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Tahir W, Abdulrahman B, Abdelaziz DH, Thapa S, Walia R, Schätzl HM. An astrocyte cell line that differentially propagates murine prions. J Biol Chem 2020; 295:11572-11583. [PMID: 32561641 PMCID: PMC7450132 DOI: 10.1074/jbc.ra120.012596] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 06/08/2020] [Indexed: 01/09/2023] Open
Abstract
Prion diseases are fatal infectious neurodegenerative disorders in human and animals caused by misfolding of the cellular prion protein (PrPC) into the pathological isoform PrPSc. Elucidating the molecular and cellular mechanisms underlying prion propagation may help to develop disease interventions. Cell culture systems for prion propagation have greatly advanced molecular insights into prion biology, but translation of in vitro to in vivo findings is often disappointing. A wider range of cell culture systems might help overcome these shortcomings. Here, we describe an immortalized mouse neuronal astrocyte cell line (C8D1A) that can be infected with murine prions. Both PrPC protein and mRNA levels in astrocytes were comparable with those in neuronal and non-neuronal cell lines permitting persistent prion infection. We challenged astrocytes with three mouse-adapted prion strains (22L, RML, and ME7) and cultured them for six passages. Immunoblotting results revealed that the astrocytes propagated 22L prions well over all six passages, whereas ME7 prions did not replicate, and RML prions replicated only very weakly after five passages. Immunofluorescence analysis indicated similar results for PrPSc. Interestingly, when we used prion conversion activity as a readout in real-time quaking-induced conversion assays with RML-infected cell lysates, we observed a strong signal over all six passages, comparable with that for 22L-infected cells. These data indicate that the C8D1A cell line is permissive to prion infection. Moreover, the propagated prions differed in conversion and proteinase K–resistance levels in these astrocytes. We propose that the C8D1A cell line could be used to decipher prion strain biology.
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Affiliation(s)
- Waqas Tahir
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Basant Abdulrahman
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Dalia H Abdelaziz
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Simrika Thapa
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Rupali Walia
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Hermann M Schätzl
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada .,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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10
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Thapa S, Abdelaziz DH, Abdulrahman BA, Schatzl HM. Sephin1 Reduces Prion Infection in Prion-Infected Cells and Animal Model. Mol Neurobiol 2020; 57:2206-2219. [PMID: 31981074 DOI: 10.1007/s12035-020-01880-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 01/15/2020] [Indexed: 02/05/2023]
Abstract
Prion diseases are fatal infectious neurodegenerative disorders in human and animals caused by misfolding of the cellular prion protein (PrPC) into the infectious isoform PrPSc. These diseases have the potential to transmit within or between species, and no cure is available to date. Targeting the unfolded protein response (UPR) as an anti-prion therapeutic approach has been widely reported for prion diseases. Here, we describe the anti-prion effect of the chemical compound Sephin1 which has been shown to protect in mouse models of protein misfolding diseases including amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) by selectively inhibiting the stress-induced regulatory subunit of protein phosphatase 1, thus prolonging eIF2α phosphorylation. We show here that Sephin1 dose and time dependently reduced PrPSc in different neuronal cell lines which were persistently infected with various prion strains. In addition, prion seeding activity was reduced in Sephin1-treated cells. Importantly, we found that Sephin1 significantly overcame the endoplasmic reticulum (ER) stress induced in treated cells, as measured by lower expression of stress-induced aberrant prion protein. In a mouse model of prion infection, intraperitoneal treatment with Sephin1 significantly prolonged survival of prion-infected mice. When combining Sephin1 with the neuroprotective drug metformin, the survival of prion-infected mice was also prolonged. These results suggest that Sephin1 could be a potential anti-prion drug selectively targeting one component of the UPR pathway.
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Affiliation(s)
- Simrika Thapa
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, TRW 2D10, 3280 Hospital Drive NW, Calgary, Alberta, T2N 4Z6, Canada.,Hotchkiss Brain Institute (HBI), University of Calgary, Calgary, Alberta, Canada
| | - Dalia H Abdelaziz
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, TRW 2D10, 3280 Hospital Drive NW, Calgary, Alberta, T2N 4Z6, Canada.,Hotchkiss Brain Institute (HBI), University of Calgary, Calgary, Alberta, Canada.,Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Basant A Abdulrahman
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada.,Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, TRW 2D10, 3280 Hospital Drive NW, Calgary, Alberta, T2N 4Z6, Canada.,Hotchkiss Brain Institute (HBI), University of Calgary, Calgary, Alberta, Canada.,Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Hermann M Schatzl
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, Canada. .,Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, TRW 2D10, 3280 Hospital Drive NW, Calgary, Alberta, T2N 4Z6, Canada. .,Hotchkiss Brain Institute (HBI), University of Calgary, Calgary, Alberta, Canada.
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11
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Hackl S, Becker CFW. Prion protein-Semisynthetic prion protein (PrP) variants with posttranslational modifications. J Pept Sci 2019; 25:e3216. [PMID: 31713950 PMCID: PMC6899880 DOI: 10.1002/psc.3216] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/23/2019] [Accepted: 08/23/2019] [Indexed: 12/16/2022]
Abstract
Deciphering the pathophysiologic events in prion diseases is challenging, and the role of posttranslational modifications (PTMs) such as glypidation and glycosylation remains elusive due to the lack of homogeneous protein preparations. So far, experimental studies have been limited in directly analyzing the earliest events of the conformational change of cellular prion protein (PrPC ) into scrapie prion protein (PrPSc ) that further propagates PrPC misfolding and aggregation at the cellular membrane, the initial site of prion infection, and PrP misfolding, by a lack of suitably modified PrP variants. PTMs of PrP, especially attachment of the glycosylphosphatidylinositol (GPI) anchor, have been shown to be crucially involved in the PrPSc formation. To this end, semisynthesis offers a unique possibility to understand PrP behavior invitro and invivo as it provides access to defined site-selectively modified PrP variants. This approach relies on the production and chemoselective linkage of peptide segments, amenable to chemical modifications, with recombinantly produced protein segments. In this article, advances in understanding PrP conversion using semisynthesis as a tool to obtain homogeneous posttranslationally modified PrP will be discussed.
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Affiliation(s)
- Stefanie Hackl
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Vienna, Austria
| | - Christian F W Becker
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Vienna, Austria
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12
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Walia R, Ho CC, Lee C, Gilch S, Schatzl HM. Gene-edited murine cell lines for propagation of chronic wasting disease prions. Sci Rep 2019; 9:11151. [PMID: 31371793 PMCID: PMC6673760 DOI: 10.1038/s41598-019-47629-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 07/18/2019] [Indexed: 01/28/2023] Open
Abstract
Prions cause fatal infectious neurodegenerative diseases in humans and animals. Cell culture models are essential for studying the molecular biology of prion propagation. Defining such culture models is mostly a random process, includes extensive subcloning, and for many prion diseases few or no models exist. One example is chronic wasting disease (CWD), a highly contagious prion disease of cervids. To extend the range of cell models propagating CWD prions, we gene-edited mouse cell lines known to efficiently propagate murine prions. Endogenous prion protein (PrP) was ablated in CAD5 and MEF cells, using CRISPR-Cas9 editing. PrP knock-out cells were reconstituted with mouse, bank vole and cervid PrP genes by lentiviral transduction. Reconstituted cells expressing mouse PrP provided proof-of-concept for re-established prion infection. Bank voles are considered universal receptors for prions from a variety of species. Bank vole PrP reconstituted cells propagated mouse prions and cervid prions, even without subcloning for highly susceptible cells. Cells reconstituted with cervid PrP and infected with CWD prions tested positive in prion conversion assay, whereas non-reconstituted cells were negative. This novel cell culture platform which is easily adjustable and allows testing of polymorphic alleles will provide important new insights into the biology of CWD prions.
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Affiliation(s)
- Rupali Walia
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | - Cheng Ching Ho
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | - Chi Lee
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | - Sabine Gilch
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada.,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | - Hermann M Schatzl
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada. .,Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada.
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13
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Quemé‐Peña M, Juhász T, Mihály J, Cs. Szigyártó I, Horváti K, Bősze S, Henczkó J, Pályi B, Németh C, Varga Z, Zsila F, Beke‐Somfai T. Manipulating Active Structure and Function of Cationic Antimicrobial Peptide CM15 with the Polysulfonated Drug Suramin: A Step Closer to in Vivo Complexity. Chembiochem 2019; 20:1578-1590. [PMID: 30720915 PMCID: PMC6618317 DOI: 10.1002/cbic.201800801] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Indexed: 12/11/2022]
Abstract
Antimicrobial peptides (AMPs) kill bacteria by targeting their membranes through various mechanisms involving peptide assembly, often coupled with disorder-to-order structural transition. However, for several AMPs, similar conformational changes in cases in which small organic compounds of both endogenous and exogenous origin have induced folded peptide conformations have recently been reported. Thus, the function of AMPs and of natural host defence peptides can be significantly affected by the local complex molecular environment in vivo; nonetheless, this area is hardly explored. To address the relevance of such interactions with regard to structure and function, we have tested the effects of the therapeutic drug suramin on the membrane activity and antibacterial efficiency of CM15, a potent hybrid AMP. The results provided insight into a dynamic system in which peptide interaction with lipid bilayers is interfered with by the competitive binding of CM15 to suramin, resulting in an equilibrium dependent on peptide-to-drug ratio and vesicle surface charge. In vitro bacterial tests showed that when CM15⋅suramin complex formation dominates over membrane binding, antimicrobial activity is abolished. On the basis of this case study, it is proposed that small-molecule secondary structure regulators can modify AMP function and that this should be considered and could potentially be exploited in future development of AMP-based antimicrobial agents.
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Affiliation(s)
- Mayra Quemé‐Peña
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Tünde Juhász
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Judith Mihály
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Imola Cs. Szigyártó
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Kata Horváti
- MTA-ELTE Research Group of Peptide ChemistryHungarian Academy of SciencesEötvös Loránd UniversityPázmány Péter sétány 1/A1117BudapestHungary
| | - Szilvia Bősze
- MTA-ELTE Research Group of Peptide ChemistryHungarian Academy of SciencesEötvös Loránd UniversityPázmány Péter sétány 1/A1117BudapestHungary
| | - Judit Henczkó
- National Biosafety LaboratoryNational Public Health CenterAlbert Flórián út 21097BudapestHungary
| | - Bernadett Pályi
- National Biosafety LaboratoryNational Public Health CenterAlbert Flórián út 21097BudapestHungary
| | - Csaba Németh
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Zoltán Varga
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Ferenc Zsila
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Tamás Beke‐Somfai
- Institute of Materials and Environmental ChemistryResearch Centre for Natural SciencesHungarian Academy of SciencesMagyar tudósok körútja 21117BudapestHungary
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14
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Abstract
Recent advances in understanding of the molecular biology of prion diseases and improved clinical diagnostic techniques might allow researchers to think about therapeutic trials in Creutzfeldt-Jakob disease (CJD) patients. Some attempts have been made in the past and various compounds have been tested in single case reports and patient series. Controlled trials are rare. However, in the past few years, it has been demonstrated that clinical trials are feasible. The clinicians might face several specific problems when evaluating the efficacy of the drug in CJD, such as rareness of the disease, lack of appropriate preclinical tests and heterogeneous clinical presentation in humans. These problems have to be carefully addressed in future.
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Affiliation(s)
- Saima Zafar
- Clinical Dementia Center and German Center for Neurodegenerative Diseases, Department of Neurology, Georg-August University, University Medical Center Göttingen, Göttingen, Germany; Biomedical Engineering and Sciences Department, School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology, Islamabad, Pakistan
| | - Aneeqa Noor
- Clinical Dementia Center and German Center for Neurodegenerative Diseases, Department of Neurology, Georg-August University, University Medical Center Göttingen, Göttingen, Germany
| | - Inga Zerr
- Clinical Dementia Center and German Center for Neurodegenerative Diseases, Department of Neurology, Georg-August University, University Medical Center Göttingen, Göttingen, Germany.
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15
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Thapa S, Abdulrahman B, Abdelaziz DH, Lu L, Ben Aissa M, Schatzl HM. Overexpression of quality control proteins reduces prion conversion in prion-infected cells. J Biol Chem 2018; 293:16069-16082. [PMID: 30154245 PMCID: PMC6187620 DOI: 10.1074/jbc.ra118.002754] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/09/2018] [Indexed: 11/06/2022] Open
Abstract
Prion diseases are fatal infectious neurodegenerative disorders in humans and other animals and are caused by misfolding of the cellular prion protein (PrPC) into the pathological isoform PrPSc. These diseases have the potential to transmit within or between species, including zoonotic transmission to humans. Elucidating the molecular and cellular mechanisms underlying prion propagation and transmission is therefore critical for developing molecular strategies for disease intervention. We have shown previously that impaired quality control mechanisms directly influence prion propagation. In this study, we manipulated cellular quality control pathways in vitro by stably and transiently overexpressing selected quality control folding (ERp57) and cargo (VIP36) proteins and investigated the effects of this overexpression on prion propagation. We found that ERp57 or VIP36 overexpression in persistently prion-infected neuroblastoma cells significantly reduces the amount of PrPSc in immunoblots and prion-seeding activity in the real-time quaking-induced conversion (RT-QuIC) assay. Using different cell lines infected with various prion strains confirmed that this effect is not cell type– or prion strain–specific. Moreover, de novo prion infection revealed that the overexpression significantly reduced newly formed PrPSc in acutely infected cells. ERp57-overexpressing cells significantly overcame endoplasmic reticulum stress, as revealed by expression of lower levels of the stress markers BiP and CHOP, accompanied by a decrease in PrP aggregates. Furthermore, application of ERp57-expressing lentiviruses prolonged the survival of prion-infected mice. Taken together, improved cellular quality control via ERp57 or VIP36 overexpression impairs prion propagation and could be utilized as a potential therapeutic strategy.
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Affiliation(s)
- Simrika Thapa
- From the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
| | - Basant Abdulrahman
- From the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, 11795 Cairo, Egypt, and
| | - Dalia H Abdelaziz
- From the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, 11795 Cairo, Egypt, and
| | - Li Lu
- From the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
| | - Manel Ben Aissa
- From the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
| | - Hermann M Schatzl
- From the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada, .,the Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Departments of Veterinary Sciences and of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071
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16
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Abdulrahman BA, Abdelaziz DH, Schatzl HM. Autophagy regulates exosomal release of prions in neuronal cells. J Biol Chem 2018; 293:8956-8968. [PMID: 29700113 PMCID: PMC5995502 DOI: 10.1074/jbc.ra117.000713] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 04/19/2018] [Indexed: 12/29/2022] Open
Abstract
Prions are protein-based infectious agents that autocatalytically convert the cellular prion protein PrPC to its pathological isoform PrPSc. Subsequent aggregation and accumulation of PrPSc in nervous tissues causes several invariably fatal neurodegenerative diseases in humans and animals. Prions can infect recipient cells when packaged into endosome-derived nanoparticles called exosomes, which are present in biological fluids such as blood, urine, and saliva. Autophagy is a basic cellular degradation and recycling machinery that also affects exosomal processing, but whether autophagy controls release of prions in exosomes is unclear. Our work investigated the effect of autophagy modulation on exosomal release of prions and how this interplay affects cellular prion infection. Exosomes isolated from cultured murine central neuronal cells (CAD5) and peripheral neuronal cells (N2a) contained prions as shown by immunoblotting for PrPSc, prion-conversion activity, and cell culture infection. We observed that autophagy stimulation with the mTOR inhibitor rapamycin strongly inhibited exosomal prion release. In contrast, inhibition of autophagy by wortmannin or CRISPR/Cas9-mediated knockout of the autophagy protein Atg5 (autophagy-related 5) greatly increased the release of exosomes and exosome-associated prions. We also show that a difference in exosomal prion release between CAD5 and N2a cells is related to differences at the level of basal autophagy. Taken together, our results indicate that autophagy modulation can control lateral transfer of prions by interfering with their exosomal release. We describe a novel role of autophagy in the prion life cycle, an understanding that may provide useful targets for containing prion diseases.
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Affiliation(s)
- Basant A Abdulrahman
- From the Department of Comparative Biology & Experimental Medicine and.,the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, 11795 Cairo, Egypt, and
| | - Dalia H Abdelaziz
- From the Department of Comparative Biology & Experimental Medicine and.,the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, 11795 Cairo, Egypt, and
| | - Hermann M Schatzl
- From the Department of Comparative Biology & Experimental Medicine and .,the Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada.,the Departments of Veterinary Sciences and of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071
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17
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Engelke AD, Gonsberg A, Thapa S, Jung S, Ulbrich S, Seidel R, Basu S, Multhaup G, Baier M, Engelhard M, Schätzl HM, Winklhofer KF, Tatzelt J. Dimerization of the cellular prion protein inhibits propagation of scrapie prions. J Biol Chem 2018; 293:8020-8031. [PMID: 29636413 DOI: 10.1074/jbc.ra117.000990] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 04/06/2018] [Indexed: 11/06/2022] Open
Abstract
A central step in the pathogenesis of prion diseases is the conformational transition of the cellular prion protein (PrPC) into the scrapie isoform, denoted PrPSc Studies in transgenic mice have indicated that this conversion requires a direct interaction between PrPC and PrPSc; however, insights into the underlying mechanisms are still missing. Interestingly, only a subfraction of PrPC is converted in scrapie-infected cells, suggesting that not all PrPC species are suitable substrates for the conversion. On the basis of the observation that PrPC can form homodimers under physiological conditions with the internal hydrophobic domain (HD) serving as a putative dimerization domain, we wondered whether PrP dimerization is involved in the formation of neurotoxic and/or infectious PrP conformers. Here, we analyzed the possible impact on dimerization of pathogenic mutations in the HD that induce a spontaneous neurodegenerative disease in transgenic mice. Similarly to wildtype (WT) PrPC, the neurotoxic variant PrP(AV3) formed homodimers as well as heterodimers with WTPrPC Notably, forced PrP dimerization via an intermolecular disulfide bond did not interfere with its maturation and intracellular trafficking. Covalently linked PrP dimers were complex glycosylated, GPI-anchored, and sorted to the outer leaflet of the plasma membrane. However, forced PrPC dimerization completely blocked its conversion into PrPSc in chronically scrapie-infected mouse neuroblastoma cells. Moreover, PrPC dimers had a dominant-negative inhibition effect on the conversion of monomeric PrPC Our findings suggest that PrPC monomers are the major substrates for PrPSc propagation and that it may be possible to halt prion formation by stabilizing PrPC dimers.
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Affiliation(s)
- Anna D Engelke
- Department of Biochemistry of Neurodegenerative Diseases, Ruhr University Bochum, D-44801 Bochum, Germany
| | - Anika Gonsberg
- Department of Biochemistry of Neurodegenerative Diseases, Ruhr University Bochum, D-44801 Bochum, Germany
| | - Simrika Thapa
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, and Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
| | - Sebastian Jung
- Department of Biochemistry of Neurodegenerative Diseases, Ruhr University Bochum, D-44801 Bochum, Germany
| | - Sarah Ulbrich
- Department of Biochemistry of Neurodegenerative Diseases, Ruhr University Bochum, D-44801 Bochum, Germany
| | - Ralf Seidel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Shaon Basu
- Department of Pharmacology and Therapeutics, McGill University, Montreal H3G 1Y6, Canada
| | - Gerd Multhaup
- Department of Pharmacology and Therapeutics, McGill University, Montreal H3G 1Y6, Canada
| | - Michael Baier
- Research Group Proteinopathies/Neurodegenerative Diseases, Centre for Biological Threats and Special Pathogens (ZBS6), Robert Koch-Institut, D-13353 Berlin, Germany
| | - Martin Engelhard
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Hermann M Schätzl
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, and Calgary Prion Research Unit, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
| | - Konstanze F Winklhofer
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44801 Bochum, Germany
| | - Jörg Tatzelt
- Department of Biochemistry of Neurodegenerative Diseases, Ruhr University Bochum, D-44801 Bochum, Germany.
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18
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Interaction of Peptide Aptamers with Prion Protein Central Domain Promotes α-Cleavage of PrP C. Mol Neurobiol 2018; 55:7758-7774. [PMID: 29460268 PMCID: PMC6132731 DOI: 10.1007/s12035-018-0944-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 01/31/2018] [Indexed: 11/03/2022]
Abstract
Prion diseases are infectious and fatal neurodegenerative diseases affecting humans and animals. Transmission is possible within and between species with zoonotic potential. Currently, no prophylaxis or treatment exists. Prions are composed of the misfolded isoform PrPSc of the cellular prion protein PrPC. Expression of PrPC is a prerequisite for prion infection, and conformational conversion of PrPC is induced upon its direct interaction with PrPSc. Inhibition of this interaction can abrogate prion propagation, and we have previously established peptide aptamers (PAs) binding to PrPC as new anti-prion compounds. Here, we mapped the interaction site of PA8 in PrP and modeled the complex in silico to design targeted mutations in PA8 which presumably enhance binding properties. Using these PA8 variants, we could improve PA-mediated inhibition of PrPSc replication and de novo infection of neuronal cells. Furthermore, we demonstrate that binding of PA8 and its variants increases PrPC α-cleavage and interferes with its internalization. This gives rise to high levels of the membrane-anchored PrP-C1 fragment, a transdominant negative inhibitor of prion replication. PA8 and its variants interact with PrPC at its central and most highly conserved domain, a region which is crucial for prion conversion and facilitates toxic signaling of Aβ oligomers characteristic for Alzheimer's disease. Our strategy allows for the first time to induce α-cleavage, which occurs within this central domain, independent of targeting the responsible protease. Therefore, interaction of PAs with PrPC and enhancement of α-cleavage represent mechanisms that can be beneficial for the treatment of prion and other neurodegenerative diseases.
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19
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Abdulrahman BA, Abdelaziz D, Thapa S, Lu L, Jain S, Gilch S, Proniuk S, Zukiwski A, Schatzl HM. The celecoxib derivatives AR-12 and AR-14 induce autophagy and clear prion-infected cells from prions. Sci Rep 2017; 7:17565. [PMID: 29242534 PMCID: PMC5730578 DOI: 10.1038/s41598-017-17770-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 11/30/2017] [Indexed: 01/05/2023] Open
Abstract
Prion diseases are fatal infectious neurodegenerative disorders that affect both humans and animals. The autocatalytic conversion of the cellular prion protein (PrPC) into the pathologic isoform PrPSc is a key feature in prion pathogenesis. AR-12 is an IND-approved derivative of celecoxib that demonstrated preclinical activity against several microbial diseases. Recently, AR-12 has been shown to facilitate clearance of misfolded proteins. The latter proposes AR-12 to be a potential therapeutic agent for neurodegenerative disorders. In this study, we investigated the role of AR-12 and its derivatives in controlling prion infection. We tested AR-12 in prion infected neuronal and non-neuronal cell lines. Immunoblotting and confocal microscopy results showed that AR-12 and its analogue AR-14 reduced PrPSc levels after only 72 hours of treatment. Furthermore, infected cells were cured of PrPSc after exposure of AR-12 or AR-14 for only two weeks. We partially attribute the influence of the AR compounds on prion propagation to autophagy stimulation, in line with our previous findings that drug-induced stimulation of autophagy has anti-prion effects in vitro and in vivo. Taken together, this study demonstrates that AR-12 and the AR-14 analogue are potential new therapeutic agents for prion diseases and possibly protein misfolding disorders involving prion-like mechanisms.
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Affiliation(s)
- Basant A Abdulrahman
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Department of Biochemistry & Molecular Biology, Faculty of Pharmacy, Helwan University, 11795, Cairo, Egypt
| | - Dalia Abdelaziz
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Department of Biochemistry & Molecular Biology, Faculty of Pharmacy, Helwan University, 11795, Cairo, Egypt
| | - Simrika Thapa
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | - Li Lu
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | - Shubha Jain
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | - Sabine Gilch
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Department of Ecosystem & Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada
| | | | | | - Hermann M Schatzl
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada.
- Calgary Prion Research Unit, University of Calgary, Calgary, Alberta, T2N 4Z6, Canada.
- Departments of Veterinary Sciences and of Molecular Biology, University of Wyoming, Laramie, Wyoming, 82071, USA.
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20
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Puig B, Altmeppen HC, Glatzel M. Misfolding leads the way to unraveling signaling pathways in the pathophysiology of prion diseases. Prion 2017; 10:434-443. [PMID: 27870599 DOI: 10.1080/19336896.2016.1244593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A misfolded version of the prion protein represents an essential component in the pathophysiology of fatal neurodegenerative prion diseases, which affect humans and animals alike. They may be of sporadic origin, acquired through exogenous introduction of infectious misfolded prion protein, or caused by genetic alterations in the prion protein coding gene. We have recently described a novel pathway linking retention of mutant prion protein in the early secretory pathway to activation p38-MAPK and a neurodegenerative phenotype in transgenic mice. Here we review the consequences that mutations in prion protein have on intracellular transport and stress responses focusing on protein quality control. We also discuss the neurotoxic signaling elicited by the accumulation of mutant prion protein in the endoplasmic reticulum and the Golgi apparatus. Improved knowledge about these processes will help us to better understand complex pathogenesis of prion diseases, a prerequisite for therapeutic strategies.
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Affiliation(s)
- Berta Puig
- a Institute of Neuropathology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Hermann C Altmeppen
- a Institute of Neuropathology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Markus Glatzel
- a Institute of Neuropathology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
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21
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Immunization of cervidized transgenic mice with multimeric deer prion protein induces self-antibodies that antagonize chronic wasting disease infectivity in vitro. Sci Rep 2017; 7:10538. [PMID: 28874781 PMCID: PMC5585258 DOI: 10.1038/s41598-017-11235-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/18/2017] [Indexed: 12/14/2022] Open
Abstract
Chronic wasting disease (CWD) is the most contagious prion disease. It is expanding rapidly in North America, was found recently in Europe, and the potential for transmission to humans cannot be excluded yet. We hypothesized that it is possible to prevent peripheral CWD infection and CWD prion shedding by inducing auto-antibodies against the cellular prion protein (PrPC) by active vaccination. Our objective is to overcome self-tolerance against PrP by using a multimeric recombinant PrP (recPrP) as an immunogen. We expressed in E. coli, purified and refolded four immunogens: cervid and murine recPrP in monomeric and dimeric form. Testing immunogenicity in sera of the vaccinated transgenic mice expressing cervid PrP revealed that all four immunogens effectively overcame self-tolerance against the prion protein as shown by high antibody titers. Confocal microscopy analysis revealed effective binding of post-immune sera to surface-located PrPC in both murine and cervid PrP expressing cultured cells. Remarkably, the post-immune auto-antibodies effectively inhibited CWD-induced prion conversion in RT-QuIC assay when incubated with either PrP substrate or CWD seed. Furthermore, they mitigated prion propagation in CWD-infected cervid-PrP expressing RK13 cells. Together, multimeric recombinant cervid PrP effectively overcomes self-tolerance to PrP and induces auto-antibodies that interfere with CWD conversion in vitro.
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22
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Fehlinger A, Wolf H, Hossinger A, Duernberger Y, Pleschka C, Riemschoss K, Liu S, Bester R, Paulsen L, Priola SA, Groschup MH, Schätzl HM, Vorberg IM. Prion strains depend on different endocytic routes for productive infection. Sci Rep 2017; 7:6923. [PMID: 28761068 PMCID: PMC5537368 DOI: 10.1038/s41598-017-07260-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/27/2017] [Indexed: 01/08/2023] Open
Abstract
Prions are unconventional agents composed of misfolded prion protein that cause fatal neurodegenerative diseases in mammals. Prion strains induce specific neuropathological changes in selected brain areas. The mechanism of strain-specific cell tropism is unknown. We hypothesised that prion strains rely on different endocytic routes to invade and replicate within their target cells. Using prion permissive cells, we determined how impairment of endocytosis affects productive infection by prion strains 22L and RML. We demonstrate that early and late stages of prion infection are differentially sensitive to perturbation of clathrin- and caveolin-mediated endocytosis. Manipulation of canonical endocytic pathways only slightly influenced prion uptake. However, blocking the same routes had drastic strain-specific consequences on the establishment of infection. Our data argue that prion strains use different endocytic pathways for infection and suggest that cell type-dependent differences in prion uptake could contribute to host cell tropism.
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Affiliation(s)
- Andrea Fehlinger
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Hanna Wolf
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - André Hossinger
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Yvonne Duernberger
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Catharina Pleschka
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Katrin Riemschoss
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Shu Liu
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Romina Bester
- Institut für Virologie, Technische Universität München, Trogerstr. 30, 81675, München, Germany
| | - Lydia Paulsen
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Suzette A Priola
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT, 59840, USA
| | - Martin H Groschup
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, 17493, Greifswald-Insel Riems, Germany
| | - Hermann M Schätzl
- Dept. of Comparative Biology & Experimental Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Ina M Vorberg
- Deutsches Zentrum für Neurodegenerative Erkrankungen e.V., Sigmund-Freud-Strasse 27, 53127, Bonn, Germany. .,Department of Neurology, Rheinische Friedrich-Wilhelms-Universität, 53127, Bonn, Germany.
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Exploring Anti-Prion Glyco-Based and Aromatic Scaffolds: A Chemical Strategy for the Quality of Life. Molecules 2017; 22:molecules22060864. [PMID: 28538692 PMCID: PMC6152669 DOI: 10.3390/molecules22060864] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 01/08/2023] Open
Abstract
Prion diseases are fatal neurodegenerative disorders caused by protein misfolding and aggregation, affecting the brain progressively and consequently the quality of life. Alzheimer’s is also a protein misfolding disease, causing dementia in over 40 million people worldwide. There are no therapeutics able to cure these diseases. Cellular prion protein is a high-affinity binding partner of amyloid β (Aβ) oligomers, the most toxic species in Alzheimer’s pathology. These findings motivate the development of new chemicals for a better understanding of the events involved. Disease control is far from being reached by the presently known therapeutics. In this review we describe the synthesis and mode of action of molecular entities with intervention in prion diseases’ biological processes and, if known, their role in Alzheimer’s. A diversity of structures is covered, based on glycans, steroids and terpenes, heterocycles, polyphenols, most of them embodying aromatics and a structural complexity. These molecules may be regarded as chemical tools to foster the understanding of the complex mechanisms involved, and to encourage the scientific community towards further developments for the cure of these devastating diseases.
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Ishibashi D, Nakagaki T, Ishikawa T, Atarashi R, Watanabe K, Cruz FA, Hamada T, Nishida N. Structure-Based Drug Discovery for Prion Disease Using a Novel Binding Simulation. EBioMedicine 2016; 9:238-249. [PMID: 27333028 PMCID: PMC4972544 DOI: 10.1016/j.ebiom.2016.06.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 05/25/2016] [Accepted: 06/06/2016] [Indexed: 12/22/2022] Open
Abstract
The accumulation of abnormal prion protein (PrP(Sc)) converted from the normal cellular isoform of PrP (PrP(C)) is assumed to induce pathogenesis in prion diseases. Therefore, drug discovery studies for these diseases have focused on the protein conversion process. We used a structure-based drug discovery algorithm (termed Nagasaki University Docking Engine: NUDE) that ran on an intensive supercomputer with a graphic-processing unit to identify several compounds with anti-prion effects. Among the candidates showing a high-binding score, the compounds exhibited direct interaction with recombinant PrP in vitro, and drastically reduced PrP(Sc) and protein-aggresomes in the prion-infected cells. The fragment molecular orbital calculation showed that the van der Waals interaction played a key role in PrP(C) binding as the intermolecular interaction mode. Furthermore, PrP(Sc) accumulation and microgliosis were significantly reduced in the brains of treated mice, suggesting that the drug candidates provided protection from prion disease, although further in vivo tests are needed to confirm these findings. This NUDE-based structure-based drug discovery for normal protein structures is likely useful for the development of drugs to treat other conformational disorders, such as Alzheimer's disease.
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Affiliation(s)
- Daisuke Ishibashi
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Japan.
| | - Takehiro Nakagaki
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Takeshi Ishikawa
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Ryuichiro Atarashi
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, Japan
| | - Ken Watanabe
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Felipe A Cruz
- Nagasaki Advanced Computing Center, Nagasaki University, Japan
| | - Tsuyoshi Hamada
- Nagasaki Advanced Computing Center, Nagasaki University, Japan
| | - Noriyuki Nishida
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Japan
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25
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Shim SY, Karri S, Law S, Schatzl HM, Gilch S. Prion infection impairs lysosomal degradation capacity by interfering with rab7 membrane attachment in neuronal cells. Sci Rep 2016; 6:21658. [PMID: 26865414 PMCID: PMC4749993 DOI: 10.1038/srep21658] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/28/2016] [Indexed: 11/24/2022] Open
Abstract
Prions are proteinaceous infectious particles which cause fatal neurodegenerative disorders in humans and animals. They consist of a mostly β-sheeted aggregated isoform (PrPSc) of the cellular prion protein (PrPc). Prions replicate autocatalytically in neurons and other cell types by inducing conformational conversion of PrPc into PrPSc. Within neurons, PrPSc accumulates at the plasma membrane and in vesicles of the endocytic pathway. To better understand the mechanisms underlying neuronal dysfunction and death it is critical to know the impact of PrPSc accumulation on cellular pathways. We have investigated the effects of prion infection on endo-lysosomal transport. Our study demonstrates that prion infection interferes with rab7 membrane association. Consequently, lysosomal maturation and degradation are impaired. Our findings indicate a mechanism induced by prion infection that supports stable prion replication. We suggest modulation of endo-lysosomal vesicle trafficking and enhancement of lysosomal maturation as novel targets for the treatment of prion diseases.
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Affiliation(s)
- Su Yeon Shim
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Srinivasarao Karri
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Sampson Law
- Dept. of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Hermann M Schatzl
- Dept. of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Sabine Gilch
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
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26
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Tewari R, Bachert C, Linstedt AD. Induced oligomerization targets Golgi proteins for degradation in lysosomes. Mol Biol Cell 2015; 26:4427-37. [PMID: 26446839 PMCID: PMC4666137 DOI: 10.1091/mbc.e15-04-0207] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 09/29/2015] [Indexed: 01/07/2023] Open
Abstract
Oligomerization or homotypic clustering diverts Golgi membrane proteins into the canonical GGA1/clathrin-dependent Golgi-to-lysosome pathway revealing the presence of cellular quality control that could be useful for therapies designed to down-regulate specific proteins in the secretory pathway. Manganese protects cells against forms of Shiga toxin by down-regulating the cycling Golgi protein GPP130. Down-regulation occurs when Mn binding causes GPP130 to oligomerize and traffic to lysosomes. To determine how GPP130 is redirected to lysosomes, we tested the role of GGA1 and clathrin, which mediate sorting in the canonical Golgi-to-lysosome pathway. GPP130 oligomerization was induced using either Mn or a self-interacting version of the FKBP domain. Inhibition of GGA1 or clathrin specifically blocked GPP130 redistribution, suggesting recognition of the aggregated GPP130 by the GGA1/clathrin-sorting complex. Unexpectedly, however, GPP130’s cytoplasmic domain was not required, and redistribution also occurred after removal of GPP130 sequences needed for its normal cycling. Therefore, to test whether aggregate recognition might be a general phenomenon rather than one involving a specific GPP130 determinant, we induced homo-oligomerization of two unrelated Golgi-targeted constructs using the FKBP strategy. These were targeted to the cis- and trans-Golgi, respectively, using domains from mannosidase-1 and galactosyltransferase. Significantly, upon oligomerization, each redistributed to peripheral punctae and was degraded. This occurred in the absence of detectable UPR activation. These findings suggest the unexpected presence of quality control in the Golgi that recognizes aggregated Golgi proteins and targets them for degradation in lysosomes.
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Affiliation(s)
- Ritika Tewari
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Collin Bachert
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Adam D Linstedt
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
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27
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Abstract
UNLABELLED Mammalian prions are unconventional infectious agents composed primarily of the misfolded aggregated host prion protein PrP, termed PrP(Sc). Prions propagate by the recruitment and conformational conversion of cellular prion protein into abnormal prion aggregates on the cell surface or along the endocytic pathway. Cellular glycosaminoglycans have been implicated as the first attachment sites for prions and cofactors for cellular prion replication. Glycosaminoglycan mimetics and obstruction of glycosaminoglycan sulfation affect prion replication, but the inhibitory effects on different strains and different stages of the cell infection have not been thoroughly addressed. We examined the effects of a glycosaminoglycan mimetic and undersulfation on cellular prion protein metabolism, prion uptake, and the establishment of productive infections in L929 cells by two mouse-adapted prion strains. Surprisingly, both treatments reduced endogenous sulfated glycosaminoglycans but had divergent effects on cellular PrP levels. Chemical or genetic manipulation of glycosaminoglycans did not prevent PrP(Sc) uptake, arguing against their roles as essential prion attachment sites. However, both treatments effectively antagonized de novo prion infection independently of the prion strain and reduced PrP(Sc) formation in chronically infected cells. Our results demonstrate that sulfated glycosaminoglycans are dispensable for prion internalization but play a pivotal role in persistently maintained PrP(Sc) formation independent of the prion strain. IMPORTANCE Recently, glycosaminoglycans (GAGs) became the focus of neurodegenerative disease research as general attachment sites for cell invasion by pathogenic protein aggregates. GAGs influence amyloid formation in vitro. GAGs are also found in intra- and extracellular amyloid deposits. In light of the essential role GAGs play in proteinopathies, understanding the effects of GAGs on protein aggregation and aggregate dissemination is crucial for therapeutic intervention. Here, we show that GAGs are dispensable for prion uptake but play essential roles in downstream infection processes. GAG mimetics also affect cellular GAG levels and localization and thus might affect prion propagation by depleting intracellular cofactor pools.
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28
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Goold R, McKinnon C, Tabrizi SJ. Prion degradation pathways: Potential for therapeutic intervention. Mol Cell Neurosci 2015; 66:12-20. [PMID: 25584786 PMCID: PMC4503822 DOI: 10.1016/j.mcn.2014.12.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 12/16/2014] [Indexed: 12/18/2022] Open
Abstract
Prion diseases are fatal neurodegenerative disorders. Pathology is closely linked to the misfolding of native cellular PrP(C) into the disease-associated form PrP(Sc) that accumulates in the brain as disease progresses. Although treatments have yet to be developed, strategies aimed at stimulating the degradation of PrP(Sc) have shown efficacy in experimental models of prion disease. Here, we describe the cellular pathways that mediate PrP(Sc) degradation and review possible targets for therapeutic intervention. This article is part of a Special Issue entitled 'Neuronal Protein'.
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Affiliation(s)
- Rob Goold
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, United Kingdom
| | - Chris McKinnon
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, United Kingdom
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, United Kingdom.
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29
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Oelschlegel AM, Geissen M, Lenk M, Riebe R, Angermann M, Schaetzl H, Groschup MH. A bovine cell line that can be infected by natural sheep scrapie prions. PLoS One 2015; 10:e0117154. [PMID: 25565633 PMCID: PMC4286239 DOI: 10.1371/journal.pone.0117154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 12/19/2014] [Indexed: 11/18/2022] Open
Abstract
Cell culture systems represent a crucial part in basic prion research; yet, cell lines that are susceptible to prions, especially to field isolated prions that were not adapted to rodents, are very rare. The purpose of this study was to identify and characterize a cell line that was susceptible to ruminant-derived prions and to establish a stable prion infection within it. Based on species and tissue of origin as well as PrP expression rate, we pre-selected a total of 33 cell lines that were then challenged with natural and with mouse propagated BSE or scrapie inocula. Here, we report the successful infection of a non-transgenic bovine cell line, a sub-line of the bovine kidney cell line MDBK, with natural sheep scrapie prions. This cell line retained the scrapie infection for more than 200 passages. Selective cloning resulted in cell populations with increased accumulation of PrPres, although this treatment was not mandatory for retaining the infection. The infection remained stable, even under suboptimal culture conditions. The resulting infectivity of the cells was confirmed by mouse bioassay (Tgbov mice, Tgshp mice). We believe that PES cells used together with other prion permissive cell lines will prove a valuable tool for ongoing efforts to understand and defeat prions and prion diseases.
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Affiliation(s)
- Anja M. Oelschlegel
- Institute of Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Greifswald—Isle of Riems, Germany
- Project Group Neuropharmacology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Markus Geissen
- Institute of Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Greifswald—Isle of Riems, Germany
- Department of Vascular Medicine, University Heart Centre Hamburg, UKE, Hamburg, Germany
| | - Matthias Lenk
- Department of Experimental Animal Facilities and Biorisk Management at the Friedrich-Loeffler-Institut, Greifswald—Isle of Riems, Germany
| | - Roland Riebe
- Department of Experimental Animal Facilities and Biorisk Management at the Friedrich-Loeffler-Institut, Greifswald—Isle of Riems, Germany
| | - Marlies Angermann
- Institute of Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Greifswald—Isle of Riems, Germany
- Administrative District Office Goerlitz, Goerlitz, Germany
| | - Hermann Schaetzl
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Martin H. Groschup
- Institute of Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Greifswald—Isle of Riems, Germany
- * E-mail:
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30
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Cholesterol balance in prion diseases and Alzheimer's disease. Viruses 2014; 6:4505-35. [PMID: 25419621 PMCID: PMC4246236 DOI: 10.3390/v6114505] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/08/2014] [Accepted: 11/14/2014] [Indexed: 12/16/2022] Open
Abstract
Prion diseases are transmissible and fatal neurodegenerative disorders of humans and animals. They are characterized by the accumulation of PrPSc, an aberrantly folded isoform of the cellular prion protein PrPC, in the brains of affected individuals. PrPC is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosyl-phosphatidyl-inositol (GPI) anchor. Specifically, it is associated with lipid rafts, membrane microdomains enriched in cholesterol and sphinoglipids. It has been established that inhibition of endogenous cholesterol synthesis disturbs lipid raft association of PrPC and prevents PrPSc accumulation in neuronal cells. Additionally, prion conversion is reduced upon interference with cellular cholesterol uptake, endosomal export, or complexation at the plasma membrane. Altogether, these results demonstrate on the one hand the importance of cholesterol for prion propagation. On the other hand, growing evidence suggests that prion infection modulates neuronal cholesterol metabolism. Similar results were reported in Alzheimer’s disease (AD): whereas amyloid β peptide formation is influenced by cellular cholesterol, levels of cholesterol in the brains of affected individuals increase during the clinical course of the disease. In this review, we summarize commonalities of alterations in cholesterol homeostasis and discuss consequences for neuronal function and therapy of prion diseases and AD.
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31
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Salta E, Kanata E, Ouzounis CA, Gilch S, Schätzl H, Sklaviadis T. Assessing proteinase K resistance of fish prion proteins in a scrapie-infected mouse neuroblastoma cell line. Viruses 2014; 6:4398-421. [PMID: 25402173 PMCID: PMC4246229 DOI: 10.3390/v6114398] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/23/2014] [Accepted: 11/06/2014] [Indexed: 11/16/2022] Open
Abstract
The key event in prion pathogenesis is the structural conversion of the normal cellular protein, PrP(C), into an aberrant and partially proteinase K resistant isoform, PrP(Sc). Since the minimum requirement for a prion disease phenotype is the expression of endogenous PrP in the host, species carrying orthologue prion genes, such as fish, could in theory support prion pathogenesis. Our previous work has demonstrated the development of abnormal protein deposition in sea bream brain, following oral challenge of the fish with natural prion infectious material. In this study, we used a prion-infected mouse neuroblastoma cell line for the expression of three different mature fish PrP proteins and the evaluation of the resistance of the exogenously expressed proteins to proteinase K treatment (PK), as an indicator of a possible prion conversion. No evidence of resistance to PK was detected for any of the studied recombinant proteins. Although not indicative of an absolute inability of the fish PrPs to structurally convert to pathogenic isoforms, the absence of PK-resistance may be due to supramolecular and conformational differences between the mammalian and piscine PrPs.
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Affiliation(s)
- Evgenia Salta
- Laboratory for the Research of Neurodegenerative Diseases, Center for Human Genetics, KU Leuven, O&N 4 Herestraat 49, PO Box 602, 3000 Leuven, Belgium.
| | - Eirini Kanata
- Department of Pharmacy, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
| | - Christos A Ouzounis
- Biological Computation & Process Laboratory (BCPL), Chemical Process Research Institute (CPERI), Centre for Research & Technology (CERTH), PO Box 361, GR-57001 Thessaloniki, Greece.
| | - Sabine Gilch
- Faculty of Veterinary Medicine, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
| | - Hermann Schätzl
- Faculty of Veterinary Medicine, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
| | - Theodoros Sklaviadis
- Department of Pharmacy, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
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Torrente MP, Castellano LM, Shorter J. Suramin inhibits Hsp104 ATPase and disaggregase activity. PLoS One 2014; 9:e110115. [PMID: 25299406 PMCID: PMC4192545 DOI: 10.1371/journal.pone.0110115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/17/2014] [Indexed: 12/16/2022] Open
Abstract
Hsp104 is a hexameric AAA+ protein that utilizes energy from ATP hydrolysis to dissolve disordered protein aggregates as well as amyloid fibers. Interestingly, Hsp104 orthologues are found in all kingdoms of life except animals. Thus, Hsp104 could represent an interesting drug target. Specific inhibition of Hsp104 activity might antagonize non-metazoan parasites that depend on a potent heat shock response, while producing little or no side effects to the host. However, no small molecule inhibitors of Hsp104 are known except guanidinium chloride. Here, we screen over 16,000 small molecules and identify 16 novel inhibitors of Hsp104 ATPase activity. Excluding compounds that inhibited Hsp104 activity by non-specific colloidal effects, we defined Suramin as an inhibitor of Hsp104 ATPase activity. Suramin is a polysulphonated naphthylurea and is used as an antiprotozoal drug for African Trypanosomiasis. Suramin also interfered with Hsp104 disaggregase, unfoldase, and translocase activities, and the inhibitory effect of Suramin was not rescued by Hsp70 and Hsp40. Suramin does not disrupt Hsp104 hexamers and does not effectively inhibit ClpB, the E. coli homolog of Hsp104, establishing yet another key difference between Hsp104 and ClpB behavior. Intriguingly, a potentiated Hsp104 variant, Hsp104A503V, is more sensitive to Suramin than wild-type Hsp104. By contrast, Hsp104 variants bearing inactivating sensor-1 mutations in nucleotide-binding domain (NBD) 1 or 2 are more resistant to Suramin. Thus, Suramin depends upon ATPase events at both NBDs to exert its maximal effect. Suramin could develop into an important mechanistic probe to study Hsp104 structure and function.
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Affiliation(s)
- Mariana P. Torrente
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Laura M. Castellano
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - James Shorter
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Pharmacology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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33
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Chu NK, Shabbir W, Bove-Fenderson E, Araman C, Lemmens-Gruber R, Harris DA, Becker CFW. A C-terminal membrane anchor affects the interactions of prion proteins with lipid membranes. J Biol Chem 2014; 289:30144-60. [PMID: 25217642 DOI: 10.1074/jbc.m114.587345] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Membrane attachment via a C-terminal glycosylphosphatidylinositol anchor is critical for conversion of PrP(C) into pathogenic PrP(Sc). Therefore the effects of the anchor on PrP structure and function need to be deciphered. Three PrP variants, including full-length PrP (residues 23-231, FL_PrP), N-terminally truncated PrP (residues 90-231, T_PrP), and PrP missing its central hydrophobic region (Δ105-125, ΔCR_PrP), were equipped with a C-terminal membrane anchor via a semisynthesis strategy. Analyses of the interactions of lipidated PrPs with phospholipid membranes demonstrated that C-terminal membrane attachment induces a different binding mode of PrP to membranes, distinct from that of non-lipidated PrPs, and influences the biochemical and conformational properties of PrPs. Additionally, fluorescence-based assays indicated pore formation by lipidated ΔCR_PrP, a variant that is known to be highly neurotoxic in transgenic mice. This finding was supported by using patch clamp electrophysiological measurements of cultured cells. These results provide new evidence for the role of the membrane anchor in PrP-lipid interactions, highlighting the importance of the N-terminal and the central hydrophobic domain in these interactions.
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Affiliation(s)
- Nam K Chu
- From the Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Waheed Shabbir
- the Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria, and
| | - Erin Bove-Fenderson
- the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Can Araman
- From the Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Rosa Lemmens-Gruber
- the Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria, and
| | - David A Harris
- the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Christian F W Becker
- From the Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria,
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Ludewigs H, Zuber C, Vana K, Nikles D, Zerr I, Weiss S. Therapeutic approaches for prion disorders. Expert Rev Anti Infect Ther 2014; 5:613-30. [PMID: 17678425 DOI: 10.1586/14787210.5.4.613] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Prion diseases are lethal for both humans and animals, and affected individuals die after several months following a rapid disease progression. Although researchers have attempted for decades to develop effective therapeutics for the therapy of human prion disorders, until now no efficient drug has been available on the market for transmissible spongiform encephalopathy (TSE) treatment or cure. Approximately 200 patients worldwide have died or suffer from variant Creutzfeldt-Jakob disease (CJD). Incidences for sporadic and familial CJD are approximately 1.5-2 per million per year and one per 10 million per year, respectively, in Europe. This review summarizes classical and modern trials for the development of effective anti-TSE drugs, introduces potential effective delivery systems, such as lentiviral and adeno-associated virus systems for antiprion components, including antibodies and siRNAs, and presents vaccination trials. Most of the antiprion drugs target prion protein PrP(c) and/or PrP(Sc). Alternative targets are receptors and coreceptors for PrP, that is, the 37/67-kDa laminin receptor and heparan sulfate proteoglycanes. We review clinical trials for the treatment of TSEs and describe hindrances and chances for a breakthrough in therapy of prion disorders.
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Affiliation(s)
- Heike Ludewigs
- Laboratorium für Molekulare Biologie, Genzentrum, Institut für Biochemie der LMU München, München, Germany.
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35
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Brazier MW, Wall VA, Brazier BW, Masters CL, Collins SJ. Therapeutic interventions ameliorating prion disease. Expert Rev Anti Infect Ther 2014; 7:83-105. [DOI: 10.1586/14787210.7.1.83] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Prions Ex Vivo: What Cell Culture Models Tell Us about Infectious Proteins. Int J Cell Biol 2013; 2013:704546. [PMID: 24282413 PMCID: PMC3825132 DOI: 10.1155/2013/704546] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/03/2013] [Indexed: 11/25/2022] Open
Abstract
Prions are unconventional infectious agents that are composed of misfolded aggregated prion protein. Prions replicate their conformation by template-assisted conversion of the endogenous prion protein PrP. Templated conversion of soluble proteins into protein aggregates is also a hallmark of other neurodegenerative diseases. Alzheimer's disease or Parkinson's disease are not considered infectious diseases, although aggregate pathology appears to progress in a stereotypical fashion reminiscent of the spreading behavior ofmammalian prions. While basic principles of prion formation have been studied extensively, it is still unclear what exactly drives PrP molecules into an infectious, self-templating conformation. In this review, we discuss crucial steps in the life cycle of prions that have been revealed in ex vivo models. Importantly, the persistent propagation of prions in mitotically active cells argues that cellular processes are in place that not only allow recruitment of cellular PrP into growing prion aggregates but also enable the multiplication of infectious seeds that are transmitted to daughter cells. Comparison of prions with other protein aggregates demonstrates that not all the characteristics of prions are equally shared by prion-like aggregates. Future experiments may reveal to which extent aggregation-prone proteins associated with other neurodegenerative diseases can copy the replication strategies of prions.
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Taguchi Y, Mistica AMA, Kitamoto T, Schätzl HM. Critical significance of the region between Helix 1 and 2 for efficient dominant-negative inhibition by conversion-incompetent prion protein. PLoS Pathog 2013; 9:e1003466. [PMID: 23825952 PMCID: PMC3694865 DOI: 10.1371/journal.ppat.1003466] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 05/13/2013] [Indexed: 01/01/2023] Open
Abstract
Prion diseases are fatal infectious neurodegenerative disorders in man and animals associated with the accumulation of the pathogenic isoform PrPSc of the host-encoded prion protein (PrPc). A profound conformational change of PrPc underlies formation of PrPSc and prion propagation involves conversion of PrPc substrate by direct interaction with PrPSc template. Identifying the interfaces and modalities of inter-molecular interactions of PrPs will highly advance our understanding of prion propagation in particular and of prion-like mechanisms in general. To identify the region critical for inter-molecular interactions of PrP, we exploited here dominant-negative inhibition (DNI) effects of conversion-incompetent, internally-deleted PrP (ΔPrP) on co-expressed conversion-competent PrP. We created a series of ΔPrPs with different lengths of deletions in the region between first and second α-helix (H1∼H2) which was recently postulated to be of importance in prion species barrier and PrP fibril formation. As previously reported, ΔPrPs uniformly exhibited aberrant properties including detergent insolubility, limited protease digestion resistance, high-mannose type N-linked glycans, and intracellular localization. Although formerly controversial, we demonstrate here that ΔPrPs have a GPI anchor attached. Surprisingly, despite very similar biochemical and cell-biological properties, DNI efficiencies of ΔPrPs varied significantly, dependant on location and inversely correlated with the size of deletion. This data demonstrates that H1∼H2 and the region C-terminal to it are critically important for efficient DNI. It also suggests that this region is involved in PrP-PrP interaction and conversion of PrPC into PrPSc. To reconcile the paradox of how an intracellular PrP can exert DNI, we demonstrate that ΔPrPs are subject to both proteasomal and lysosomal/autophagic degradation pathways. Using autophagy pathways ΔPrPs obtain access to the locale of prion conversion and PrPSc recycling and can exert DNI there. This shows that the intracellular trafficking of PrPs is more complex than previously anticipated. Prion diseases are deadly infectious diseases of the brain characterized by accumulation of a pathologic protein (PrPSc) which is derived from the normal prion protein (PrPc). Prions replicate by direct contact in a template-directed refolding process which involves conversion of PrPC into PrPSc. Identifying the modalities of this interaction can advance our molecular understanding of prion diseases. Like substrates and competitive inhibitors of enzymes, a conversion-incompetent PrP can inhibit conversion of normal PrPC, a phenomenon known as dominant-negative inhibition (DNI). Interestingly, some conversion-incompetent PrPs efficiently cause DNI but others do not, presumably depending on affinity for PrPSc and integrity of interaction interface. We utilized DNI to characterize the PrP-PrP interaction interface in cultured cells. We created a series of PrPs with internal deletions in the region between helix 1 and 2 and evaluated their DNI. We found an inverse correlation between deletion size and DNI which suggests that this region plays an important role in PrP-PrP interaction. We also found that such PrPs are subject to various cellular degradation pathways and that a fraction of them reaches the intracellular locale of prion conversion. Further investigation of such prion proteins might help elucidating the cellular mechanisms of the PrPC-PrPSc interaction.
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Affiliation(s)
- Yuzuru Taguchi
- Departments of Veterinary Sciences and of Molecular Biology, University of Wyoming, Laramie, Wyoming, United States of America.
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Goold R, McKinnon C, Rabbanian S, Collinge J, Schiavo G, Tabrizi SJ. Alternative fates of newly formed PrPSc upon prion conversion on the plasma membrane. J Cell Sci 2013; 126:3552-62. [PMID: 23813960 DOI: 10.1242/jcs.120477] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Prion diseases are fatal neurodegenerative diseases characterised by the accumulation of misfolded prion protein (PrP(Sc)) in the brain. They are caused by the templated misfolding of normal cellular protein, PrP(C), by PrP(Sc). We have recently generated a unique cell system in which epitope-tagged PrP(C) competent to produce bona fide PrP(Sc) is expressed in neuroblastoma cells. Using this system we demonstrated that PrP(Sc) forms on the cell surface within minutes of prion exposure. Here, we describe the intracellular trafficking of newly formed PrP(Sc). After formation in GM1-enriched lipid microdomains at the plasma membrane, PrP(Sc) is rapidly internalised to early endosomes containing transferrin and cholera toxin B subunit. Following endocytosis, PrP(Sc) intracellular trafficking diverges: some is recycled to the plasma membrane via Rab11-labelled recycling endosomes; the remaining PrP(Sc) is subject to retromer-mediated retrograde transport to the Golgi. This pathway leads to lysosomal degradation, and we show that this is the dominant PrP(Sc) degradative mechanism in the early stages of prion infection.
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Affiliation(s)
- Rob Goold
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
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Kuznetsov I, Kuznetsov A. A two population model of prion transport through a tunnelling nanotube. Comput Methods Biomech Biomed Engin 2013; 17:1705-15. [DOI: 10.1080/10255842.2013.763938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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McCarthy JM, Franke M, Resenberger UK, Waldron S, Simpson JC, Tatzelt J, Appelhans D, Rogers MS. Anti-prion drug mPPIg5 inhibits PrP(C) conversion to PrP(Sc). PLoS One 2013; 8:e55282. [PMID: 23383136 PMCID: PMC3557256 DOI: 10.1371/journal.pone.0055282] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 12/29/2012] [Indexed: 11/18/2022] Open
Abstract
Prion diseases, also known as transmissible spongiform encephalopathies, are a group of fatal neurodegenerative diseases that include scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle and Creutzfeldt-Jakob disease (CJD) in humans. The ‘protein only hypothesis’ advocates that PrPSc, an abnormal isoform of the cellular protein PrPC, is the main and possibly sole component of prion infectious agents. Currently, no effective therapy exists for these diseases at the symptomatic phase for either humans or animals, though a number of compounds have demonstrated the ability to eliminate PrPSc in cell culture models. Of particular interest are synthetic polymers known as dendrimers which possess the unique ability to eliminate PrPSc in both an intracellular and in vitro setting. The efficacy and mode of action of the novel anti-prion dendrimer mPPIg5 was investigated through the creation of a number of innovative bio-assays based upon the scrapie cell assay. These assays were used to demonstrate that mPPIg5 is a highly effective anti-prion drug which acts, at least in part, through the inhibition of PrPC to PrPSc conversion. Understanding how a drug works is a vital component in maximising its performance. By establishing the efficacy and method of action of mPPIg5, this study will help determine which drugs are most likely to enhance this effect and also aid the design of dendrimers with anti-prion capabilities for the future.
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Affiliation(s)
- James M McCarthy
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin, Ireland.
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41
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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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Severe acute respiratory syndrome coronavirus replication is severely impaired by MG132 due to proteasome-independent inhibition of M-calpain. J Virol 2012; 86:10112-22. [PMID: 22787216 DOI: 10.1128/jvi.01001-12] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The ubiquitin-proteasome system (UPS) is involved in the replication of a broad range of viruses. Since replication of the murine hepatitis virus (MHV) is impaired upon proteasomal inhibition, the relevance of the UPS for the replication of the severe acute respiratory syndrome coronavirus (SARS-CoV) was investigated in this study. We demonstrate that the proteasomal inhibitor MG132 strongly inhibits SARS-CoV replication by interfering with early steps of the viral life cycle. Surprisingly, other proteasomal inhibitors (e.g., lactacystin and bortezomib) only marginally affected viral replication, indicating that the effect of MG132 is independent of proteasomal impairment. Induction of autophagy by MG132 treatment was excluded from playing a role, and no changes in SARS-CoV titers were observed during infection of wild-type or autophagy-deficient ATG5(-/-) mouse embryonic fibroblasts overexpressing the human SARS-CoV receptor, angiotensin-converting enzyme 2 (ACE2). Since MG132 also inhibits the cysteine protease m-calpain, we addressed the role of calpains in the early SARS-CoV life cycle using calpain inhibitors III (MDL28170) and VI (SJA6017). In fact, m-calpain inhibition with MDL28170 resulted in an even more pronounced inhibition of SARS-CoV replication (>7 orders of magnitude) than did MG132. Additional m-calpain knockdown experiments confirmed the dependence of SARS-CoV replication on the activity of the cysteine protease m-calpain. Taken together, we provide strong experimental evidence that SARS-CoV has unique replication requirements which are independent of functional UPS or autophagy pathways compared to other coronaviruses. Additionally, this work highlights an important role for m-calpain during early steps of the SARS-CoV life cycle.
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Invernizzi G, Papaleo E, Sabate R, Ventura S. Protein aggregation: mechanisms and functional consequences. Int J Biochem Cell Biol 2012; 44:1541-54. [PMID: 22713792 DOI: 10.1016/j.biocel.2012.05.023] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/09/2012] [Accepted: 05/27/2012] [Indexed: 12/31/2022]
Abstract
Understanding the mechanisms underlying protein misfolding and aggregation has become a central issue in biology and medicine. Compelling evidence show that the formation of amyloid aggregates has a negative impact in cell function and is behind the most prevalent human degenerative disorders, including Alzheimer's Parkinson's and Huntington's diseases or type 2 diabetes. Surprisingly, the same type of macromolecular assembly is used for specialized functions by different organisms, from bacteria to human. Here we address the conformational properties of these aggregates, their formation pathways, their role in human diseases, their functional properties and how bioinformatics tools might be of help to study these protein assemblies.
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Affiliation(s)
- Gaetano Invernizzi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
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Iwamaru Y, Takenouchi T, Murayama Y, Okada H, Imamura M, Shimizu Y, Hashimoto M, Mohri S, Yokoyama T, Kitani H. Anti-prion activity of Brilliant Blue G. PLoS One 2012; 7:e37896. [PMID: 22693582 PMCID: PMC3365075 DOI: 10.1371/journal.pone.0037896] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 04/30/2012] [Indexed: 12/11/2022] Open
Abstract
Background Prion diseases are fatal neurodegenerative disorders with no effective therapy currently available. Accumulating evidence has implicated over-activation of P2X7 ionotropic purinergic receptor (P2X7R) in the progression of neuronal loss in several neurodegenerative diseases. This has led to the speculation that simultaneous blockade of this receptor and prion replication can be an effective therapeutic strategy for prion diseases. We have focused on Brilliant Blue G (BBG), a well-known P2X7R antagonist, possessing a chemical structure expected to confer anti-prion activity and examined its inhibitory effect on the accumulation of pathogenic isoforms of prion protein (PrPres) in a cellular and a mouse model of prion disease in order to determine its therapeutic potential. Principal Findings BBG prevented PrPres accumulation in infected MG20 microglial and N2a neural cells at 50% inhibitory concentrations of 14.6 and 3.2 µM, respectively. Administration of BBG in vivo also reduced PrPres accumulation in the brains of mice with prion disease. However, it did not appear to alleviate the disease progression compared to the vehicle-treated controls, implying a complex role of P2X7R on the neuronal degeneration in prion diseases. Significance These results provide novel insights into the pathophysiology of prion diseases and have important implications for the treatment.
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Affiliation(s)
- Yoshifumi Iwamaru
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Takato Takenouchi
- Animal Immune and Cell Biology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Yuichi Murayama
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Hiroyuki Okada
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Morikazu Imamura
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Yoshihisa Shimizu
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Makoto Hashimoto
- Division of Sensory and Motor Systems, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan
| | - Shirou Mohri
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Takashi Yokoyama
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Hiroshi Kitani
- Animal Immune and Cell Biology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
- * E-mail:
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Common healthcare challenges. PLASMA MEDICINE 2012. [DOI: 10.1017/cbo9780511902598.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Prion subcellular fractionation reveals infectivity spectrum, with a high titre-low PrPres level disparity. Mol Neurodegener 2012; 7:18. [PMID: 22534096 PMCID: PMC3355018 DOI: 10.1186/1750-1326-7-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 04/26/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Prion disease transmission and pathogenesis are linked to misfolded, typically protease resistant (PrPres) conformers of the normal cellular prion protein (PrPC), with the former posited to be the principal constituent of the infectious 'prion'. Unexplained discrepancies observed between detectable PrPres and infectivity levels exemplify the complexity in deciphering the exact biophysical nature of prions and those host cell factors, if any, which contribute to transmission efficiency. In order to improve our understanding of these important issues, this study utilized a bioassay validated cell culture model of prion infection to investigate discordance between PrPres levels and infectivity titres at a subcellular resolution. FINDINGS Subcellular fractions enriched in lipid rafts or endoplasmic reticulum/mitochondrial marker proteins were equally highly efficient at prion transmission, despite lipid raft fractions containing up to eight times the levels of detectable PrPres. Brain homogenate infectivity was not differentially enhanced by subcellular fraction-specific co-factors, and proteinase K pre-treatment of selected fractions modestly, but equally reduced infectivity. Only lipid raft associated infectivity was enhanced by sonication. CONCLUSIONS This study authenticates a subcellular disparity in PrPres and infectivity levels, and eliminates simultaneous divergence of prion strains as the explanation for this phenomenon. On balance, the results align best with the concept that transmission efficiency is influenced more by intrinsic characteristics of the infectious prion, rather than cellular microenvironment conditions or absolute PrPres levels.
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Nunziante M, Ackermann K, Dietrich K, Wolf H, Gädtke L, Gilch S, Vorberg I, Groschup M, Schätzl HM. Proteasomal dysfunction and endoplasmic reticulum stress enhance trafficking of prion protein aggregates through the secretory pathway and increase accumulation of pathologic prion protein. J Biol Chem 2011; 286:33942-53. [PMID: 21835918 DOI: 10.1074/jbc.m111.272617] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A conformational change of the cellular prion protein (PrP(c)) underlies formation of PrP(Sc), which is closely associated with pathogenesis and transmission of prion diseases. The precise conformational prerequisites and the cellular environment necessary for this post-translational process remain to be completely elucidated. At steady state, glycosylated PrP(c) is found primarily at the cell surface, whereas a minor fraction of the population is disposed of by the ER-associated degradation-proteasome pathway. However, chronic ER stress conditions and proteasomal dysfunctions lead to accumulation of aggregation-prone PrP molecules in the cytosol and to neurodegeneration. In this study, we challenged different cell lines by inducing ER stress or inhibiting proteasomal activity and analyzed the subsequent repercussion on PrP metabolism, focusing on PrP in the secretory pathway. Both events led to enhanced detection of PrP aggregates and a significant increase of PrP(Sc) in persistently prion-infected cells, which could be reversed by overexpression of proteins of the cellular quality control. Remarkably, upon proteasomal impairment, an increased fraction of misfolded, fully glycosylated PrP molecules traveled through the secretory pathway and reached the plasma membrane. These findings suggest a novel pathway that possibly provides additional substrate and template necessary for prion formation when protein clearance by the proteasome is impaired.
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Affiliation(s)
- Max Nunziante
- Institute of Virology, Prion Research Group, Technische Universität München, 81675 Munich, Germany
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Geissen M, Leidel F, Eiden M, Hirschberger T, Fast C, Bertsch U, Tavan P, Giese A, Kretzschmar H, Schatzl HM, Groschup MH. From high-throughput cell culture screening to mouse model: identification of new inhibitor classes against prion disease. ChemMedChem 2011; 6:1928-37. [PMID: 21755599 DOI: 10.1002/cmdc.201100119] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 06/21/2011] [Indexed: 11/10/2022]
Abstract
Transmissible spongiform encephalopathies (TSE) or prion diseases belong to a category of fatal and so far untreatable neurodegenerative conditions. All prion diseases are characterized by both degeneration in the central nervous system (CNS) in humans and animals and the deposition and accumulation of Proteinase K-resistant prion protein (PrP(res)). Until now, no pharmaceutical product has been available to cure these diseases or to alleviate their associated symptoms. Here, a cell-culture screening system is described that allows for the large-scale analysis of the PrP(res) inhibitory potential of a library of compounds and the identification of structural motifs leading potent compounds able to cause PrP(res) clearance at the cellular level. Based on different scrapie-infected cell lines, 10,000 substances were tested, out of which 530 potential inhibitors were identified. After re-screening and validation using a series of dilutions, 14 compounds were identified as the most effective. These 14 compounds were then used for therapeutic studies in a mouse bioassay to test and verify their in vivo potency. Two compounds exhibited therapeutic potential in the mouse model by significantly extending the survival time of intracerebrally infected mice, when treated 90 days after infection with scrapie.
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Affiliation(s)
- Markus Geissen
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute for Novel and Emerging Infectious Diseases, Suedufer 10, 17493 Greifswald-Insel Riems, Germany
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50
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Poncet-Montange G, St Martin SJ, Bogatova OV, Prusiner SB, Shoichet BK, Ghaemmaghami S. A survey of antiprion compounds reveals the prevalence of non-PrP molecular targets. J Biol Chem 2011; 286:27718-28. [PMID: 21610081 DOI: 10.1074/jbc.m111.234393] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prion diseases are fatal neurodegenerative diseases caused by the accumulation of the misfolded isoform (PrP(Sc)) of the prion protein (PrP(C)). Cell-based screens have identified several compounds that induce a reduction in PrP(Sc) levels in infected cultured cells. However, the molecular targets of most antiprion compounds remain unknown. We undertook a large-scale, unbiased, cell-based screen for antiprion compounds and then investigated whether a representative subset of the active molecules had measurable affinity for PrP, increased the susceptibility of PrP(Sc) to proteolysis, or altered the cellular localization or expression level of PrP(C). None of the antiprion compounds showed in vitro affinity for PrP or had the ability to disaggregate PrP(Sc) in infected brain homogenates. These observations suggest that most antiprion compounds identified in cell-based screens deploy their activity via non-PrP targets in the cell. Our findings indicate that in comparison to PrP conformers themselves, proteins that play auxiliary roles in prion propagation may be more effective targets for future drug discovery efforts.
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