1
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Woerman AL, Bartz JC. Effect of host and strain factors on α-synuclein prion pathogenesis. Trends Neurosci 2024; 47:538-550. [PMID: 38806297 PMCID: PMC11236502 DOI: 10.1016/j.tins.2024.05.004] [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: 02/27/2024] [Revised: 04/19/2024] [Accepted: 05/04/2024] [Indexed: 05/30/2024]
Abstract
Prion diseases are a group of neurodegenerative disorders caused by misfolding of proteins into pathogenic conformations that self-template to spread disease. Although this mechanism is largely associated with the prion protein (PrP) in classical prion diseases, a growing literature indicates that other proteins, including α-synuclein, rely on a similar disease mechanism. Notably, α-synuclein misfolds into distinct conformations, or strains, that cause discrete clinical disorders including multiple system atrophy (MSA) and Parkinson's disease (PD). Because the recognized similarities between PrP and α-synuclein are increasing, this review article draws from research on PrP to identify the host and strain factors that impact disease pathogenesis, predominantly in rodent models, and focuses on key considerations for future research on α-synuclein prions.
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Affiliation(s)
- Amanda L Woerman
- Department of Microbiology, Immunology, and Pathology, Prion Research Center, Colorado State University, Fort Collins, CO, USA.
| | - Jason C Bartz
- Department of Microbiology, Immunology, and Pathology, Prion Research Center, Colorado State University, Fort Collins, CO, USA; Department of Medical Microbiology and Immunology, School of Medicine, Creighton University, Omaha, NE, USA.
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2
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Wu J, Wang X, Lakkaraju A, Sternke-Hoffmann R, Qureshi BM, Aguzzi A, Luo J. Channel Activities of the Full-Length Prion and Truncated Proteins. ACS Chem Neurosci 2024; 15:98-107. [PMID: 38096481 DOI: 10.1021/acschemneuro.3c00412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024] Open
Abstract
Prion diseases are fatal neurodegenerative disorders characterized by the conversion of the cellular prion protein (PrPC) into a misfolded prion form, which is believed to disrupt the cellular membranes. However, the exact mechanisms underlying prion toxicity, including the formation of membrane pores, are not fully understood. The prion protein consists of two domains: a globular domain (GD) and a flexible N-terminus (FT) domain. Although a proximal polybasic amino acid (FT(23-31) sequence of FT is a prerequisite for cellular membrane permeabilization, other functional domain regions may modulate its effects. Through single-channel electrical recordings and cryo-electron microscopy (cryo-EM), we discovered that the FT(23-50) fragment forms pore-shaped oligomers and plays a dominant role in membrane permeabilization within the full-length mouse prion protein (mPrP(23-230)). In contrast, the FT(51-110) domain or the C-terminal domain downregulate the channel activity of FT(23-50) and mPrP(23-230). The addition of prion mimetic antibody, POM1 significantly amplifies mPrP(23-230) membrane permeabilization, whereas POM1_Y104A, a mutant that binds to PrP but cannot elicit toxicity, has a negligible effect on membrane permeabilization. Additionally, the anti-N-terminal antibody POM2 or Cu2+ binds to the FT domain, subsequently enhancing the FT(23-110) channel activity. Importantly, our setup provides a novel approach without an external fused protein to examine the channel activity of truncated PrP in the lipid membranes. We therefore propose that the primary N-terminal residues are essential for membrane permeabilization, while other functional segments of PrP play a vital role in modulating the pathological effects of PrP-mediated neurotoxicity.
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Affiliation(s)
- Jinming Wu
- Department of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Xue Wang
- Department of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Asvin Lakkaraju
- Institute of Neuropathology, University of Zurich and University Hospital Zurich, Zurich 8091, Switzerland
| | | | - Bilal M Qureshi
- Scientific Center for Optical and Electron Microscopy (ScopeM), ETH Zurich, Zurich 8093, Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology, University of Zurich and University Hospital Zurich, Zurich 8091, Switzerland
| | - Jinghui Luo
- Department of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
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3
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Beta-endoproteolysis of the cellular prion protein by dipeptidyl peptidase-4 and fibroblast activation protein. Proc Natl Acad Sci U S A 2023; 120:e2209815120. [PMID: 36574660 PMCID: PMC9910601 DOI: 10.1073/pnas.2209815120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The cellular prion protein (PrPC) converts to alternatively folded pathogenic conformations (PrPSc) in prion infections and binds neurotoxic oligomers formed by amyloid-β α-synuclein, and tau. β-Endoproteolysis, which splits PrPC into N- and C-terminal fragments (N2 and C2, respectively), is of interest because a protease-resistant, C2-sized fragment (C2Sc) accumulates in the brain during prion infections, seemingly comprising the majority of PrPSc at disease endpoint in mice. However, candidates for the underlying proteolytic mechanism(s) remain unconfirmed in vivo. Here, a cell-based screen of protease inhibitors unexpectedly linked type II membrane proteins of the S9B serine peptidase subfamily to PrPC β-cleavage. Overexpression experiments in cells and assays with recombinant proteins confirmed that fibroblast activation protein (FAP) and its paralog, dipeptidyl peptidase-4 (DPP4), cleave directly at multiple sites within PrPC's N-terminal domain. For wild-type mouse and human PrPC substrates expressed in cells, the rank orders of activity were human FAP ~ mouse FAP > mouse DPP4 > human DPP4 and human FAP > mouse FAP > mouse DPP4 >> human DPP4, respectively. C2 levels relative to total PrPC were reduced in several tissues from FAP-null mice, and, while knockout of DPP4 lacked an analogous effect, the combined DPP4/FAP inhibitor linagliptin, but not the FAP-specific inhibitor SP-13786, reduced C2Sc and total PrPSc levels in two murine cell-based models of prion infections. Thus, the net activity of the S9B peptidases FAP and DPP4 and their cognate inhibitors/modulators affect the physiology and pathogenic potential of PrPC.
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4
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Reimann RR, Puzio M, Rosati A, Emmenegger M, Schneider BL, Valdés P, Huang D, Caflisch A, Aguzzi A. Rapid ex vivo reverse genetics identifies the essential determinants of prion protein toxicity. Brain Pathol 2022; 33:e13130. [PMID: 36329611 PMCID: PMC10041163 DOI: 10.1111/bpa.13130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
The cellular prion protein PrPC mediates the neurotoxicity of prions and other protein aggregates through poorly understood mechanisms. Antibody-derived ligands against the globular domain of PrPC (GDL) can also initiate neurotoxicity by inducing an intramolecular R208 -H140 hydrogen bond ("H-latch") between the α2-α3 and β2-α2 loops of PrPC . Importantly, GDL that suppresses the H-latch prolong the life of prion-infected mice, suggesting that GDL toxicity and prion infections exploit convergent pathways. To define the structural underpinnings of these phenomena, we transduced 19 individual PrPC variants to PrPC -deficient cerebellar organotypic cultured slices using adenovirus-associated viral vectors (AAV). We report that GDL toxicity requires a single N-proximal cationic residue (K27 or R27 ) within PrPC . Alanine substitution of K27 also prevented the toxicity of PrPC mutants that induce Shmerling syndrome, a neurodegenerative disease that is suppressed by co-expression of wild-type PrPC . K27 may represent an actionable target for compounds aimed at preventing prion-related neurodegeneration.
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Affiliation(s)
| | - Martina Puzio
- Institute of Neuropathology University of Zurich Zurich Switzerland
| | - Antonella Rosati
- Institute of Neuropathology University of Zurich Zurich Switzerland
| | - Marc Emmenegger
- Institute of Neuropathology University of Zurich Zurich Switzerland
| | - Bernard L. Schneider
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne Lausanne Switzerland
| | - Pamela Valdés
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne Lausanne Switzerland
| | - Danzhi Huang
- Department of Biochemistry University of Zürich Zürich Switzerland
| | - Amedeo Caflisch
- Department of Biochemistry University of Zürich Zürich Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology University of Zurich Zurich Switzerland
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5
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Mercer RCC, Harris DA. Mechanisms of prion-induced toxicity. Cell Tissue Res 2022; 392:81-96. [PMID: 36070155 DOI: 10.1007/s00441-022-03683-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/30/2022] [Indexed: 11/02/2022]
Abstract
Prion diseases are devastating neurodegenerative diseases caused by the structural conversion of the normally benign prion protein (PrPC) to an infectious, disease-associated, conformer, PrPSc. After decades of intense research, much is known about the self-templated prion conversion process, a phenomenon which is now understood to be operative in other more common neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In this review, we provide the current state of knowledge concerning a relatively poorly understood aspect of prion diseases: mechanisms of neurotoxicity. We provide an overview of proposed functions of PrPC and its interactions with other extracellular proteins in the central nervous system, in vivo and in vitro models used to delineate signaling events downstream of prion propagation, the application of omics technologies, and the emerging appreciation of the role played by non-neuronal cell types in pathogenesis.
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Affiliation(s)
- Robert C C Mercer
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
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6
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Roy M, Nath AK, Pal I, Dey SG. Second Sphere Interactions in Amyloidogenic Diseases. Chem Rev 2022; 122:12132-12206. [PMID: 35471949 DOI: 10.1021/acs.chemrev.1c00941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloids are protein aggregates bearing a highly ordered cross β structural motif, which may be functional but are mostly pathogenic. Their formation, deposition in tissues and consequent organ dysfunction is the central event in amyloidogenic diseases. Such protein aggregation may be brought about by conformational changes, and much attention has been directed toward factors like metal binding, post-translational modifications, mutations of protein etc., which eventually affect the reactivity and cytotoxicity of the associated proteins. Over the past decade, a global effort from different groups working on these misfolded/unfolded proteins/peptides has revealed that the amino acid residues in the second coordination sphere of the active sites of amyloidogenic proteins/peptides cause changes in H-bonding pattern or protein-protein interactions, which dramatically alter the structure and reactivity of these proteins/peptides. These second sphere effects not only determine the binding of transition metals and cofactors, which define the pathology of some of these diseases, but also change the mechanism of redox reactions catalyzed by these proteins/peptides and form the basis of oxidative damage associated with these amyloidogenic diseases. The present review seeks to discuss such second sphere modifications and their ramifications in the etiopathology of some representative amyloidogenic diseases like Alzheimer's disease (AD), type 2 diabetes mellitus (T2Dm), Parkinson's disease (PD), Huntington's disease (HD), and prion diseases.
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Affiliation(s)
- Madhuparna Roy
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Arnab Kumar Nath
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Ishita Pal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Somdatta Ghosh Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B, Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
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7
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Polido SA, Kamps J, Tatzelt J. Biological Functions of the Intrinsically Disordered N-Terminal Domain of the Prion Protein: A Possible Role of Liquid-Liquid Phase Separation. Biomolecules 2021; 11:1201. [PMID: 34439867 PMCID: PMC8391301 DOI: 10.3390/biom11081201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/06/2021] [Accepted: 08/09/2021] [Indexed: 12/26/2022] Open
Abstract
The mammalian prion protein (PrPC) is composed of a large intrinsically disordered N-terminal and a structured C-terminal domain, containing three alpha-helical regions and a short, two-stranded beta-sheet. Traditionally, the activity of a protein was linked to the ability of the polypeptide chain to adopt a stable secondary/tertiary structure. This concept has been extended when it became evident that intrinsically disordered domains (IDDs) can participate in a broad range of defined physiological activities and play a major functional role in several protein classes including transcription factors, scaffold proteins, and signaling molecules. This ability of IDDs to engage in a variety of supramolecular complexes may explain the large number of PrPC-interacting proteins described. Here, we summarize diverse physiological and pathophysiological activities that have been described for the unstructured N-terminal domain of PrPC. In particular, we focus on subdomains that have been conserved in evolution.
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Affiliation(s)
- Stella A. Polido
- Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany; (S.A.P.); (J.K.)
| | - Janine Kamps
- Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany; (S.A.P.); (J.K.)
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
| | - Jörg Tatzelt
- Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany; (S.A.P.); (J.K.)
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
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8
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Overduin M, Wille H, Westaway D. Multisite interactions of prions with membranes and native nanodiscs. Chem Phys Lipids 2021; 236:105063. [PMID: 33600804 DOI: 10.1016/j.chemphyslip.2021.105063] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/29/2021] [Accepted: 02/12/2021] [Indexed: 02/05/2023]
Abstract
Although prions are known as protein-only infectious particles, they exhibit lipid specificities, cofactor dependencies and membrane-dependent activities. Such membrane interactions play key roles in how prions are processed, presented and regulated, and hence have significant functional consequences. The expansive literature related to prion protein interactions with lipids and native nanodiscs is discussed, and provides a unique opportunity to re-evaluate the molecular composition and mechanisms of its infectious and cellular states. A family of crystal and solution structures of prions are analyzed here for the first time using the membrane optimal docking area (MODA) program, revealling the presence of structured binding elements that could mediate specific lipid recognition. A set of motifs centerred around W99, L125, Y169 and Y226 are consistently predicted as being membrane interactive and form an exposed surface which includes α helical, β strand and loop elements involving the prion protein (PrP) structural domain, while the scrapie form is radically different and doubles the size of the membrane interactive site into an extensible surface. These motifs are highly conserved throughout mammalian evolution, suggesting that prions have long been intrinsically attached to membranes at central and N- and C-terminal points, providing several opportunities for stable and specific bilayer interactions as well as multiple complexed orientations. Resistance or susceptibility to prion disease correlates with increased or decreased membrane binding propensity by mutant forms, respectively, indicating a protective role by lipids. The various prion states found in vivo are increasingly resolvable using native nanodiscs formed by styrene maleic acid (SMA) and stilbene maleic acid (STMA) copolymers rather than classical detergents, allowing the endogenous states to be tackled. These copolymers spontaneously fragment intact membranes into water-soluble discs holding a section of native bilayer, and can accommodate prion multimers and mini-fibrils. Such nanodiscs have also proven useful for understanding how β amyloid and α synuclein proteins contribute to Alzheimer's and Parkinson's diseases, providing further biomedical applications. Structural and functional insights of such proteins in styrene maleic acid lipid particles (SMALPs) can be resolved at high resolution by methods including cryo-electron microscopy (cEM), motivating continued progress in polymer design to resolve biological and pathological mechanisms.
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Affiliation(s)
- Michael Overduin
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.
| | - Holger Wille
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada; Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada
| | - David Westaway
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada; Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada
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9
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Kim SY, Zhang F, Harris DA, Linhardt RJ. Structural Features of Heparin and Its Interactions With Cellular Prion Protein Measured by Surface Plasmon Resonance. Front Mol Biosci 2020; 7:594497. [PMID: 33324681 PMCID: PMC7726446 DOI: 10.3389/fmolb.2020.594497] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/14/2020] [Indexed: 01/13/2023] Open
Abstract
Self-propagating form of the prion protein (PrP Sc ) causes many neurodegenerative diseases, such as Creutzfeldt-Jakob disease (CJD) and Gerstmann-Straussler-Scheinker syndrome (GSS). Heparin is a highly sulfated linear glycosaminoglycan (GAG) and is composed of alternating D-glucosamine and L-iduronic acid or D-glucuronic acid sugar residues. The interactions of heparin with various proteins in a domain-specific or charged-dependent manner provide key roles on many physiological and pathological processes. While GAG-PrP interactions had been previously reported, the specific glycan structures that facilitate interactions with different regions of PrP and their binding kinetics have not been systematically investigated. In this study, we performed direct binding surface plasmon resonance (SPR) assay to characterize the kinetics of heparin binding to four recombinant murine PrP constructs including full length (M23-230), a deletion mutant lacking the four histidine-containing octapeptide repeats (M23-230 Δ59-90), the isolated N-terminal domain (M23-109), and the isolated C-terminal domain (M90-230). Additionally, we found the specific structural determinants required for GAG binding to the four PrP constructs with chemically defined derivatives of heparin and other GAGs by an SPR competition assay. Our findings may be instrumental in developing designer GAGs for specific targets within the PrP to fine-tune biological and pathophysiological activities of PrP.
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Affiliation(s)
- So Young Kim
- Division of Pulmonary and Critical Care, Department of Medicine, University of California, San Diego, San Diego, CA, United States.,VA San Diego Healthcare System, Medical and Research Sections, San Diego, CA, United States
| | - Fuming Zhang
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, United States
| | - Robert J Linhardt
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, United States.,Department of Chemistry and Chemical Biology, Biological Science and Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
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10
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Hara H, Sakaguchi S. N-Terminal Regions of Prion Protein: Functions and Roles in Prion Diseases. Int J Mol Sci 2020; 21:ijms21176233. [PMID: 32872280 PMCID: PMC7504422 DOI: 10.3390/ijms21176233] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 01/30/2023] Open
Abstract
The normal cellular isoform of prion protein, designated PrPC, is constitutively converted to the abnormally folded, amyloidogenic isoform, PrPSc, in prion diseases, which include Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. PrPC is a membrane glycoprotein consisting of the non-structural N-terminal domain and the globular C-terminal domain. During conversion of PrPC to PrPSc, its 2/3 C-terminal region undergoes marked structural changes, forming a protease-resistant structure. In contrast, the N-terminal region remains protease-sensitive in PrPSc. Reverse genetic studies using reconstituted PrPC-knockout mice with various mutant PrP molecules have revealed that the N-terminal domain has an important role in the normal function of PrPC and the conversion of PrPC to PrPSc. The N-terminal domain includes various characteristic regions, such as the positively charged residue-rich polybasic region, the octapeptide repeat (OR) region consisting of five repeats of an octapeptide sequence, and the post-OR region with another positively charged residue-rich polybasic region followed by a stretch of hydrophobic residues. We discuss the normal functions of PrPC, the conversion of PrPC to PrPSc, and the neurotoxicity of PrPSc by focusing on the roles of the N-terminal regions in these topics.
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11
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Senatore A, Frontzek K, Emmenegger M, Chincisan A, Losa M, Reimann R, Horny G, Guo J, Fels S, Sorce S, Zhu C, George N, Ewert S, Pietzonka T, Hornemann S, Aguzzi A. Protective anti-prion antibodies in human immunoglobulin repertoires. EMBO Mol Med 2020; 12:e12739. [PMID: 32776637 PMCID: PMC7506995 DOI: 10.15252/emmm.202012739] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/10/2020] [Accepted: 07/10/2020] [Indexed: 01/09/2023] Open
Abstract
Prion immunotherapy may hold great potential, but antibodies against certain PrP epitopes can be neurotoxic. Here, we identified > 6,000 PrP-binding antibodies in a synthetic human Fab phage display library, 49 of which we characterized in detail. Antibodies directed against the flexible tail of PrP conferred neuroprotection against infectious prions. We then mined published repertoires of circulating B cells from healthy humans and found antibodies similar to the protective phage-derived antibodies. When expressed recombinantly, these antibodies exhibited anti-PrP reactivity. Furthermore, we surveyed 48,718 samples from 37,894 hospital patients for the presence of anti-PrP IgGs and found 21 high-titer individuals. The clinical files of these individuals did not reveal any enrichment of specific pathologies, suggesting that anti-PrP autoimmunity is innocuous. The existence of anti-prion antibodies in unbiased human immunological repertoires suggests that they might clear nascent prions early in life. Combined with the reported lack of such antibodies in carriers of disease-associated PRNP mutations, this suggests a link to the low incidence of spontaneous prion diseases in human populations.
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Affiliation(s)
- Assunta Senatore
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Karl Frontzek
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Marc Emmenegger
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Andra Chincisan
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Marco Losa
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Regina Reimann
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Geraldine Horny
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Jingjing Guo
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Sylvie Fels
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Silvia Sorce
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Caihong Zhu
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Nathalie George
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Stefan Ewert
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | | | - Simone Hornemann
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
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12
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Roseman GP, Wu B, Wadolkowski MA, Harris DA, Millhauser GL. Intrinsic toxicity of the cellular prion protein is regulated by its conserved central region. FASEB J 2020; 34:8734-8748. [PMID: 32385908 DOI: 10.1096/fj.201902749rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 04/08/2020] [Accepted: 04/20/2020] [Indexed: 11/11/2022]
Abstract
The conserved central region (CR) of PrPC has been hypothesized to serve as a passive linker connecting the protein's toxic N-terminal and globular C-terminal domains. Yet, deletion of the CR causes neonatal fatality in mice, implying the CR possesses a protective function. The CR encompasses the regulatory α-cleavage locus, and additionally facilitates a regulatory metal ion-promoted interaction between the PrPC N- and C-terminal domains. To elucidate the role of the CR and determine why CR deletion generates toxicity, we designed PrPC constructs wherein either the cis-interaction or α-cleavage are selectively prevented. These constructs were interrogated using nuclear magnetic resonance, electrophysiology, and cell viability assays. Our results demonstrate the CR is not a passive linker and the native sequence is crucial for its protective role over the toxic N-terminus, irrespective of α-cleavage or the cis-interaction. Additionally, we find that the CR facilitates homodimerization of PrPC , attenuating the toxicity of the N-terminus.
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Affiliation(s)
- Graham P Roseman
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Bei Wu
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Mark A Wadolkowski
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Glenn L Millhauser
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
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13
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Structural Consequences of Copper Binding to the Prion Protein. Cells 2019; 8:cells8080770. [PMID: 31349611 PMCID: PMC6721516 DOI: 10.3390/cells8080770] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 12/24/2022] Open
Abstract
Prion, or PrPSc, is the pathological isoform of the cellular prion protein (PrPC) and it is the etiological agent of transmissible spongiform encephalopathies (TSE) affecting humans and animal species. The most relevant function of PrPC is its ability to bind copper ions through its flexible N-terminal moiety. This review includes an overview of the structure and function of PrPC with a focus on its ability to bind copper ions. The state-of-the-art of the role of copper in both PrPC physiology and in prion pathogenesis is also discussed. Finally, we describe the structural consequences of copper binding to the PrPC structure.
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14
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McDonald AJ, Leon DR, Markham KA, Wu B, Heckendorf CF, Schilling K, Showalter HD, Andrews PC, McComb ME, Pushie MJ, Costello CE, Millhauser GL, Harris DA. Altered Domain Structure of the Prion Protein Caused by Cu 2+ Binding and Functionally Relevant Mutations: Analysis by Cross-Linking, MS/MS, and NMR. Structure 2019; 27:907-922.e5. [PMID: 30956132 DOI: 10.1016/j.str.2019.03.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 01/17/2019] [Accepted: 03/14/2019] [Indexed: 12/24/2022]
Abstract
The cellular isoform of the prion protein (PrPC) serves as precursor to the infectious isoform (PrPSc), and as a cell-surface receptor, which binds misfolded protein oligomers as well as physiological ligands such as Cu2+ ions. PrPC consists of two domains: a flexible N-terminal domain and a structured C-terminal domain. Both the physiological and pathological functions of PrP depend on intramolecular interactions between these two domains, but the specific amino acid residues involved have proven challenging to define. Here, we employ a combination of chemical cross-linking, mass spectrometry, NMR, molecular dynamics simulations, and functional assays to identify residue-level contacts between the N- and C-terminal domains of PrPC. We also determine how these interdomain contacts are altered by binding of Cu2+ ions and by functionally relevant mutations. Our results provide a structural basis for interpreting both the normal and toxic activities of PrP.
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Affiliation(s)
- Alex J McDonald
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Deborah R Leon
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA; Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Kathleen A Markham
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Bei Wu
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Christian F Heckendorf
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA; Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Kevin Schilling
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Hollis D Showalter
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA
| | - Philip C Andrews
- Department of Biological Chemistry, Department of Chemistry, Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Mark E McComb
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA; Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA 02118, USA
| | - M Jake Pushie
- Department of Surgery, Division of Neurosurgery, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Catherine E Costello
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA; Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA 02118, USA.
| | - Glenn L Millhauser
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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15
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Mercer RC, Harris DA. Identification of anti-prion drugs and targets using toxicity-based assays. Curr Opin Pharmacol 2019; 44:20-27. [PMID: 30684854 DOI: 10.1016/j.coph.2018.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/18/2018] [Accepted: 12/20/2018] [Indexed: 01/24/2023]
Abstract
Prion diseases are untreatable and invariably fatal, making the discovery of effective therapeutic interventions a priority. Most candidate molecules have been discovered based on their ability to reduce the levels of PrPSc, the infectious form of the prion protein, in cultured neuroblastoma cells. We have employed an alternative assay, based on an abnormal cellular phenotype associated with a mutant prion protein, to discover a novel class of anti-prion compounds, the phenethyl piperidines. Using an assay that monitors the acute toxic effects of PrPSc on the synapses of cultured hippocampal neurons, we have identified p38 MAPK as a druggable pharmacological target that is already being pursued for the treatment of other human diseases. Organotypic brain slices, which can propagate prions and mimic several neuropathological features of the disease, have also been used to test inhibitory compounds. An effective anti-prion regimen will involve synergistic combination of drugs acting at multiple steps of the pathogenic process, resulting not only in reduction in prion levels but also suppression of neurotoxic signaling.
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Affiliation(s)
- Robert Cc Mercer
- Boston University School of Medicine, Boston, MA 02118, United States
| | - David A Harris
- Boston University School of Medicine, Boston, MA 02118, United States.
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16
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Le NTT, Wu B, Harris DA. Prion neurotoxicity. Brain Pathol 2019; 29:263-277. [PMID: 30588688 DOI: 10.1111/bpa.12694] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 11/28/2018] [Indexed: 01/04/2023] Open
Abstract
Although the mechanisms underlying prion propagation and infectivity are now well established, the processes accounting for prion toxicity and pathogenesis have remained mysterious. These processes are of enormous clinical relevance as they hold the key to identification of new molecular targets for therapeutic intervention. In this review, we will discuss two broad areas of investigation relevant to understanding prion neurotoxicity. The first is the use of in vitro experimental systems that model key events in prion pathogenesis. In this context, we will describe a hippocampal neuronal culture system we developed that reproduces the earliest pathological alterations in synaptic morphology and function in response to PrPSc . This system has allowed us to define a core synaptotoxic signaling pathway involving the activation of NMDA and AMPA receptors, stimulation of p38 MAPK phosphorylation and collapse of the actin cytoskeleton in dendritic spines. The second area concerns a striking and unexpected phenomenon in which certain structural manipulations of the PrPC molecule itself, including introduction of N-terminal deletion mutations or binding of antibodies to C-terminal epitopes, unleash powerful toxic effects in cultured cells and transgenic mice. We will describe our studies of this phenomenon, which led to the recognition that it is related to the induction of large, abnormal ionic currents by the structurally altered PrP molecules. Our results suggest a model in which the flexible N-terminal domain of PrPC serves as a toxic effector which is regulated by intramolecular interactions with the globular C-terminal domain. Taken together, these two areas of study have provided important clues to underlying cellular and molecular mechanisms of prion neurotoxicity. Nevertheless, much remains to be done on this next frontier of prion science.
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Affiliation(s)
- Nhat T T Le
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Bei Wu
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
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17
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Castle AR, Daude N, Gilch S, Westaway D. Application of high-throughput, capillary-based Western analysis to modulated cleavage of the cellular prion protein. J Biol Chem 2018; 294:2642-2650. [PMID: 30578300 DOI: 10.1074/jbc.ra118.006367] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/20/2018] [Indexed: 12/21/2022] Open
Abstract
The cellular prion protein (PrPC) is a glycoprotein that is processed through several proteolytic pathways. Modulators of PrPC proteolysis are of interest because full-length PrPC and its cleavage fragments differ in their propensity to misfold, a process that plays a key role in the pathogenesis of prion diseases. PrPC may also act as a receptor for neurotoxic, oligomeric species of other proteins that are linked to neurodegeneration. Importantly, the PrPC C-terminal fragment C1 does not contain the reported binding sites for these oligomers. Western blotting would be a simple end point detection method for cell-based screening of compound libraries for effects on PrPC proteolysis or overall expression level. However, traditional Western blotting methods provide unreliable quantification and have only low throughput. Consequently, we explored capillary-based Western technology as a potential alternative; we believe that this study is the first to report analysis of PrPC using such an approach. We successfully optimized the detection and quantification of the deglycosylated forms of full-length PrPC and its C-terminal cleavage fragments C1 and C2, including simultaneous quantification of β-tubulin levels to control for loading error. We also developed and tested a method for performing all cell culture, lysis, and deglycosylation steps in 96-well microplates prior to capillary Western analysis. These advances represent steps along the way to the development of an automated, high-throughput screening pipeline to identify modulators of PrPC expression levels or proteolysis.
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Affiliation(s)
- Andrew R Castle
- From the Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2M8, Canada.,Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
| | - Nathalie Daude
- From the Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2M8, Canada
| | - Sabine Gilch
- Department of Ecosystem and Public Health, Calgary Prion Research Unit, Faculty of Veterinary Medicine and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 1N4, Canada, and
| | - David Westaway
- From the Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2M8, Canada .,Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2G3, Canada.,Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
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18
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Prion protein inhibits fast axonal transport through a mechanism involving casein kinase 2. PLoS One 2017; 12:e0188340. [PMID: 29261664 PMCID: PMC5737884 DOI: 10.1371/journal.pone.0188340] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 11/06/2017] [Indexed: 12/13/2022] Open
Abstract
Prion diseases include a number of progressive neuropathies involving conformational changes in cellular prion protein (PrPc) that may be fatal sporadic, familial or infectious. Pathological evidence indicated that neurons affected in prion diseases follow a dying-back pattern of degeneration. However, specific cellular processes affected by PrPc that explain such a pattern have not yet been identified. Results from cell biological and pharmacological experiments in isolated squid axoplasm and primary cultured neurons reveal inhibition of fast axonal transport (FAT) as a novel toxic effect elicited by PrPc. Pharmacological, biochemical and cell biological experiments further indicate this toxic effect involves casein kinase 2 (CK2) activation, providing a molecular basis for the toxic effect of PrPc on FAT. CK2 was found to phosphorylate and inhibit light chain subunits of the major motor protein conventional kinesin. Collectively, these findings suggest CK2 as a novel therapeutic target to prevent the gradual loss of neuronal connectivity that characterizes prion diseases.
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19
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McDonald AJ, Wu B, Harris DA. An inter-domain regulatory mechanism controls toxic activities of PrP C. Prion 2017; 11:388-397. [PMID: 28960140 DOI: 10.1080/19336896.2017.1384894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The normal function of PrPC, the cellular prion protein, has remained mysterious since its first description over 30 years ago. Amazingly, although complete deletion of the gene encoding PrPC has little phenotypic consequence, expression in transgenic mice of PrP molecules carrying certain internal deletions produces dramatic neurodegenerative phenotypes. In our recent paper, 1 we have demonstrated that the flexible, N-terminal domain of PrPC possesses toxic effector functions, which are regulated by a docking interaction with the structured, C-terminal domain. Disruption of this inter-domain interaction, for example by deletions of the hinge region or by binding of antibodies to the C-terminal domain, results in abnormal ionic currents and degeneration of dendritic spines in cultured neuronal cells. This mechanism may contribute to the neurotoxicity of PrPSc and possibly other protein aggregates, and could play a role in the physiological activity of PrPC. These results also provide a warning about the potential toxic side effects of PrP-directed antibody therapies for prion and Alzheimer's diseases.
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Affiliation(s)
- Alex J McDonald
- a Department of Biochemistry , Boston University School of Medicine , Boston , MA , USA
| | - Bei Wu
- a Department of Biochemistry , Boston University School of Medicine , Boston , MA , USA
| | - David A Harris
- a Department of Biochemistry , Boston University School of Medicine , Boston , MA , USA
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20
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Copper- and Zinc-Promoted Interdomain Structure in the Prion Protein: A Mechanism for Autoinhibition of the Neurotoxic N-Terminus. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 150:35-56. [PMID: 28838668 DOI: 10.1016/bs.pmbts.2017.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
The function of the cellular prion protein (PrPC), while still poorly understood, is increasingly linked to its ability to bind physiological metal ions at the cell surface. PrPC binds divalent forms of both copper and zinc through its unstructured N-terminal domain, modulating interactions between PrPC and various receptors at the cell surface and ultimately tuning downstream cellular processes. In this chapter, we briefly discuss the molecular features of copper and zinc uptake by PrPC and summarize evidence implicating these metal ions in PrP-mediated physiology. We then focus our review on recent biophysical evidence revealing a physical interaction between the flexible N-terminal and globular C-terminal domains of PrPC. This interdomain cis interaction is electrostatic in nature and is promoted by the binding of Cu2+ and Zn2+ to the N-terminal octarepeat domain. These findings, along with recent cellular studies, suggest a mechanism whereby NC interactions serve to regulate the activity and/or toxicity of the PrPC N-terminus. We discuss this potential mechanism in relation to familial prion disease mutations, lethal deletions of the PrPC central region, and neurotoxicity induced by certain globular domain ligands, including bona fide prions and toxic amyloid-β oligomers.
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21
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Sabareesan AT, Singh J, Roy S, Udgaonkar JB, Mathew MK. The Pathogenic A116V Mutation Enhances Ion-Selective Channel Formation by Prion Protein in Membranes. Biophys J 2017; 110:1766-1776. [PMID: 27119637 DOI: 10.1016/j.bpj.2016.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/23/2016] [Accepted: 03/07/2016] [Indexed: 11/19/2022] Open
Abstract
Prion diseases are a group of fatal neurodegenerative disorders that afflict mammals. Misfolded and aggregated forms of the prion protein (PrP(Sc)) have been associated with many prion diseases. A transmembrane form of PrP favored by the pathogenic mutation A116V is associated with Gerstmann-Sträussler-Scheinker syndrome, but no accumulation of PrP(Sc) is detected. However, the role of the transmembrane form of PrP in pathological processes leading to neuronal death remains unclear. This study reports that the full-length mouse PrP (moPrP) significantly increases the permeability of living cells to K(+), and forms K(+)- and Ca(2+)-selective channels in lipid membranes. Importantly, the pathogenic mutation A116V greatly increases the channel-forming capability of moPrP. The channels thus formed are impermeable to sodium and chloride ions, and are blocked by blockers of voltage-gated ion channels. Hydrogen-deuterium exchange studies coupled with mass spectrometry (HDX-MS) show that upon interaction with lipid, the central hydrophobic region (109-132) of the protein is protected against exchange, making it a good candidate for inserting into the membrane and lining the channel. HDX-MS also shows a dramatic increase in the protein-lipid stoichiometry for A116V moPrP, providing a rationale for its increased channel-forming capability. The results suggest that ion channel formation may be a possible mechanism of PrP-mediated neurodegeneration by the transmembrane forms of PrP.
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Affiliation(s)
- Ambadi Thody Sabareesan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Jogender Singh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Samrat Roy
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India; Biocon Bristol Myers Squibb Research Center, Bengaluru, India; School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.
| | - M K Mathew
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.
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22
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Wu B, McDonald AJ, Markham K, Rich CB, McHugh KP, Tatzelt J, Colby DW, Millhauser GL, Harris DA. The N-terminus of the prion protein is a toxic effector regulated by the C-terminus. eLife 2017; 6:e23473. [PMID: 28527237 PMCID: PMC5469617 DOI: 10.7554/elife.23473] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/17/2017] [Indexed: 12/23/2022] Open
Abstract
PrPC, the cellular isoform of the prion protein, serves to transduce the neurotoxic effects of PrPSc, the infectious isoform, but how this occurs is mysterious. Here, using a combination of electrophysiological, cellular, and biophysical techniques, we show that the flexible, N-terminal domain of PrPC functions as a powerful toxicity-transducing effector whose activity is tightly regulated in cis by the globular C-terminal domain. Ligands binding to the N-terminal domain abolish the spontaneous ionic currents associated with neurotoxic mutants of PrP, and the isolated N-terminal domain induces currents when expressed in the absence of the C-terminal domain. Anti-PrP antibodies targeting epitopes in the C-terminal domain induce currents, and cause degeneration of dendrites on murine hippocampal neurons, effects that entirely dependent on the effector function of the N-terminus. NMR experiments demonstrate intramolecular docking between N- and C-terminal domains of PrPC, revealing a novel auto-inhibitory mechanism that regulates the functional activity of PrPC.
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Affiliation(s)
- Bei Wu
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Alex J McDonald
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Kathleen Markham
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, United States
| | - Celeste B Rich
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
| | - Kyle P McHugh
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, United States
| | - Jörg Tatzelt
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
- Neurobiochemistry, Adolf Butenandt Institute, Ludwig Maximilians University, Munich, Germany
| | - David W Colby
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, United States
| | - Glenn L Millhauser
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, United States
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, United States
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23
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Imberdis T, Heeres JT, Yueh H, Fang C, Zhen J, Rich CB, Glicksman M, Beeler AB, Harris DA. Identification of Anti-prion Compounds using a Novel Cellular Assay. J Biol Chem 2016; 291:26164-26176. [PMID: 27803163 DOI: 10.1074/jbc.m116.745612] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/19/2016] [Indexed: 11/06/2022] Open
Abstract
Prion diseases are devastating neurodegenerative disorders with no known cure. One strategy for developing therapies for these diseases is to identify compounds that block conversion of the cellular form of the prion protein (PrPC) into the infectious isoform (PrPSc). Most previous efforts to discover such molecules by high-throughput screening methods have utilized, as a read-out, a single kind of cellular assay system: neuroblastoma cells that are persistently infected with scrapie prions. Here, we describe the use of an alternative cellular assay based on suppressing the spontaneous cytotoxicity of a mutant form of PrP (Δ105-125). Using this assay, we screened 75,000 compounds, and identified a group of phenethyl piperidines (exemplified by LD7), which reduces the accumulation of PrPSc in infected neuroblastoma cells by >90% at low micromolar doses, and inhibits PrPSc-induced synaptotoxicity in hippocampal neurons. By analyzing the structure-activity relationships of 35 chemical derivatives, we defined the pharmacophore of LD7, and identified a more potent derivative. Active compounds do not alter total or cell-surface levels of PrPC, and do not bind to recombinant PrP in surface plasmon resonance experiments, although at high concentrations they inhibit PrPSc-seeded conversion of recombinant PrP to a misfolded state in an in vitro reaction (RT-QuIC). This class of small molecules may provide valuable therapeutic leads, as well as chemical biological tools to identify cellular pathways underlying PrPSc metabolism and PrPC function.
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Affiliation(s)
- Thibaut Imberdis
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - James T Heeres
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Han Yueh
- the Department of Chemistry, Boston University, Boston, Massachusetts 02115, and
| | - Cheng Fang
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Jessie Zhen
- the Department of Chemistry, Boston University, Boston, Massachusetts 02115, and
| | - Celeste B Rich
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Marcie Glicksman
- the Laboratory for Drug Discovery in Neurodegeneration, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139
| | - Aaron B Beeler
- the Department of Chemistry, Boston University, Boston, Massachusetts 02115, and
| | - David A Harris
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118,
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24
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Baskakov IV, Katorcha E. Multifaceted Role of Sialylation in Prion Diseases. Front Neurosci 2016; 10:358. [PMID: 27551257 PMCID: PMC4976111 DOI: 10.3389/fnins.2016.00358] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 07/18/2016] [Indexed: 11/13/2022] Open
Abstract
Mammalian prion or PrP(Sc) is a proteinaceous infectious agent that consists of a misfolded, self-replicating state of a sialoglycoprotein called the prion protein, or PrP(C). Sialylation of the prion protein N-linked glycans was discovered more than 30 years ago, yet the role of sialylation in prion pathogenesis remains poorly understood. Recent years have witnessed extraordinary growth in interest in sialylation and established a critical role for sialic acids in host invasion and host-pathogen interactions. This review article summarizes current knowledge on the role of sialylation of the prion protein in prion diseases. First, we discuss the correlation between sialylation of PrP(Sc) glycans and prion infectivity and describe the factors that control sialylation of PrP(Sc). Second, we explain how glycan sialylation contributes to the prion replication barrier, defines strain-specific glycoform ratios, and imposes constraints for PrP(Sc) structure. Third, several topics, including a possible role for sialylation in animal-to-human prion transmission, prion lymphotropism, toxicity, strain interference, and normal function of PrP(C), are critically reviewed. Finally, a metabolic hypothesis on the role of sialylation in the etiology of sporadic prion diseases is proposed.
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Affiliation(s)
- Ilia V. Baskakov
- Department of Anatomy and Neurobiology, Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimore, MD, USA
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25
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A Neuronal Culture System to Detect Prion Synaptotoxicity. PLoS Pathog 2016; 12:e1005623. [PMID: 27227882 PMCID: PMC4881977 DOI: 10.1371/journal.ppat.1005623] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/19/2016] [Indexed: 12/02/2022] Open
Abstract
Synaptic pathology is an early feature of prion as well as other neurodegenerative diseases. Although the self-templating process by which prions propagate is well established, the mechanisms by which prions cause synaptotoxicity are poorly understood, due largely to the absence of experimentally tractable cell culture models. Here, we report that exposure of cultured hippocampal neurons to PrPSc, the infectious isoform of the prion protein, results in rapid retraction of dendritic spines. This effect is entirely dependent on expression of the cellular prion protein, PrPC, by target neurons, and on the presence of a nine-amino acid, polybasic region at the N-terminus of the PrPC molecule. Both protease-resistant and protease-sensitive forms of PrPSc cause dendritic loss. This system provides new insights into the mechanisms responsible for prion neurotoxicity, and it provides a platform for characterizing different pathogenic forms of PrPSc and testing potential therapeutic agents. Prion diseases are fatal neurodegenerative disorders that cause memory loss, impaired coordination, and abnormal movements. The molecular culprit in prion diseases is PrPSc, an infectious isoform of a host-encoded glycoprotein (PrPC) that can propagate itself by a self-templating mechanism. Whether PrPSc itself is toxic to neurons, and if so, the cellular mechanisms by which it produces neuronal pathology are largely unknown, in part because of the absence of suitable cell culture models. We describe here a hippocampal neuronal cultural system to detect the toxic effect of PrPSc on dendritic spines, which are postsynaptic elements responsible for excitatory synaptic transmission, and which are implicated in learning, memory, and the earliest stages of neurodegenerative diseases. We found that purified, exogenously applied PrPSc causes acute retraction of dendritic spines, an effect that is entirely dependent on expression of PrPC by target neurons, and on the on the presence of a nine-amino acid, polybasic region at the N-terminus of the PrPC molecule. Both protease-resistant and protease-sensitive forms of PrPSc cause dendritic retraction. This system provides new insights into the mechanisms responsible for prion neurotoxicity, and it provides a platform for characterizing different pathogenic forms of PrPSc and testing potential therapeutic agents.
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26
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Nyeste A, Bencsura P, Vida I, Hegyi Z, Homolya L, Fodor E, Welker E. Expression of the Prion Protein Family Member Shadoo Causes Drug Hypersensitivity That Is Diminished by the Coexpression of the Wild Type Prion Protein. J Biol Chem 2016; 291:4473-86. [PMID: 26721882 DOI: 10.1074/jbc.m115.679035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Indexed: 11/06/2022] Open
Abstract
The prion protein (PrP) seems to exert both neuroprotective and neurotoxic activities. The toxic activities are associated with the C-terminal globular parts in the absence of the flexible N terminus, specifically the hydrophobic domain (HD) or the central region (CR). The wild type prion protein (PrP-WT), having an intact flexible part, exhibits neuroprotective qualities by virtue of diminishing many of the cytotoxic effects of these mutant prion proteins (PrPΔHD and PrPΔCR) when coexpressed. The prion protein family member Doppel, which possesses a three-dimensional fold similar to the C-terminal part of PrP, is also harmful to neuronal and other cells in various models, a phenotype that can also be eliminated by the coexpression of PrP-WT. In contrast, another prion protein family member, Shadoo (Sho), a natively disordered protein possessing structural features similar to the flexible N-terminal tail of PrP, exhibits PrP-WT-like protective properties. Here, we report that, contrary to expectations, Sho expression in SH-SY5Y or HEK293 cells induces the same toxic phenotype of drug hypersensitivity as PrPΔCR. This effect is exhibited in a dose-dependent manner and is also counteracted by the coexpression of PrP-WT. The opposing effects of Shadoo in different model systems revealed here may be explored to help discern the relationship of the various toxic activities of mutant PrPs with each other and the neurotoxic effects seen in neurodegenerative diseases, such as transmissible spongiform encephalopathy and Alzheimer disease.
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Affiliation(s)
- Antal Nyeste
- From the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Petra Bencsura
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
| | - István Vida
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and the Institute of Chemistry, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Zoltán Hegyi
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
| | - László Homolya
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
| | - Elfrieda Fodor
- From the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Ervin Welker
- From the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary, the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
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Sempou E, Biasini E, Pinzón-Olejua A, Harris DA, Málaga-Trillo E. Activation of zebrafish Src family kinases by the prion protein is an amyloid-β-sensitive signal that prevents the endocytosis and degradation of E-cadherin/β-catenin complexes in vivo. Mol Neurodegener 2016; 11:18. [PMID: 26860872 PMCID: PMC4748561 DOI: 10.1186/s13024-016-0076-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 01/18/2016] [Indexed: 11/25/2022] Open
Abstract
Background Prions and amyloid-β (Aβ) oligomers trigger neurodegeneration by hijacking a poorly understood cellular signal mediated by the prion protein (PrP) at the plasma membrane. In early zebrafish embryos, PrP-1-dependent signals control cell-cell adhesion via a tyrosine phosphorylation-dependent mechanism. Results Here we report that the Src family kinases (SFKs) Fyn and Yes act downstream of PrP-1 to prevent the endocytosis and degradation of E-cadherin/β-catenin adhesion complexes in vivo. Accordingly, knockdown of PrP-1 or Fyn/Yes cause similar zebrafish gastrulation phenotypes, whereas Fyn/Yes expression rescues the PrP-1 knockdown phenotype. We also show that zebrafish and mouse PrPs positively regulate the activity of Src kinases and that these have an unexpected positive effect on E-cadherin-mediated cell adhesion. Interestingly, while PrP knockdown impairs β-catenin adhesive function, PrP overexpression enhances it, thereby antagonizing its nuclear, wnt-related signaling activity and disturbing embryonic dorsoventral specification. The ability of mouse PrP to influence these events in zebrafish embryos requires its neuroprotective, polybasic N-terminus but not its neurotoxicity-associated central region. Remarkably, human Aβ oligomers up-regulate the PrP-1/SFK/E-cadherin/β-catenin pathway in zebrafish embryonic cells, mimicking a PrP gain-of-function scenario. Conclusions Our gain- and loss-of-function experiments in zebrafish suggest that PrP and SFKs enhance the cell surface stability of embryonic adherens junctions via the same complex mechanism through which they over-activate neuroreceptors that trigger synaptic damage. The profound impact of this pathway on early zebrafish development makes these embryos an ideal model to study the cellular and molecular events affected by neurotoxic PrP mutations and ligands in vivo. In particular, our finding that human Aβ oligomers activate the zebrafish PrP/SFK/E-cadherin pathway opens the possibility of using fish embryos to rapidly screen for novel therapeutic targets and compounds against prion- and Alzheimer's-related neurodegeneration. Altogether, our data illustrate PrP-dependent signals relevant to embryonic development, neuronal physiology and neurological disease. Electronic supplementary material The online version of this article (doi:10.1186/s13024-016-0076-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Emily Sempou
- Department of Biology, University of Konstanz, Constance, 78457, Germany. .,Present address: Department of Pediatrics, Yale University School of Medicine, New Haven, CT, 06520, USA.
| | - Emiliano Biasini
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, 02118, USA. .,Present address: Dulbecco Telethon Institute, Laboratory of Prions and Amyloids, Centre for Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy.
| | - Alejandro Pinzón-Olejua
- Department of Biology, University of Konstanz, Constance, 78457, Germany. .,Present address: Max PIanck Institute for Brain Research, Department of Synaptic Plasticity, 60438, Frankfurt/Main, Germany.
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, 02118, USA.
| | - Edward Málaga-Trillo
- Department of Biology, University of Konstanz, Constance, 78457, Germany. .,Department of Biology, Universidad Peruana Cayetano Heredia, Lima 31, Perú.
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Mutated but Not Deleted Ovine PrP(C) N-Terminal Polybasic Region Strongly Interferes with Prion Propagation in Transgenic Mice. J Virol 2015; 90:1638-46. [PMID: 26608316 DOI: 10.1128/jvi.02805-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 11/18/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Mammalian prions are proteinaceous infectious agents composed of misfolded assemblies of the host-encoded, cellular prion protein (PrP). Physiologically, the N-terminal polybasic region of residues 23 to 31 of PrP has been shown to be involved in its endocytic trafficking and interactions with glycosaminoglycans or putative ectodomains of membrane-associated proteins. Several recent reports also describe this PrP region as important for the toxicity of mutant prion proteins and the efficiency of prion propagation, both in vitro and in vivo. The question remains as to whether the latter observations made with mouse PrP and mouse prions would be relevant to other PrP species/prion strain combinations given the dramatic impact on prion susceptibility of minimal amino acid substitutions and structural variations in PrP. Here, we report that transgenic mouse lines expressing ovine PrP with a deletion of residues 23 to 26 (KKRP) or mutated in this N-terminal region (KQHPH instead of KKRPK) exhibited a variable, strain-dependent susceptibility to prion infection with regard to the proportion of affected mice and disease tempo relative to findings in their wild-type counterparts. Deletion has no major effect on 127S scrapie prion pathogenesis, whereas mutation increased by almost 3-fold the survival time of the mice. Deletion marginally affected the incubation time of scrapie LA19K and ovine bovine spongiform encephalopathy (BSE) prions, whereas mutation caused apparent resistance to disease. IMPORTANCE Recent reports suggested that the N-terminal polybasic region of the prion protein could be a therapeutic target to prevent prion propagation or toxic signaling associated with more common neurodegenerative diseases such as Alzheimer's disease. Mutating or deleting this region in ovine PrP completes the data previously obtained with the mouse protein by identifying the key amino acid residues involved.
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Iraci N, Stincardini C, Barreca ML, Biasini E. Decoding the function of the N-terminal tail of the cellular prion protein to inspire novel therapeutic avenues for neurodegenerative diseases. Virus Res 2015; 207:62-8. [DOI: 10.1016/j.virusres.2014.10.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/18/2014] [Accepted: 10/14/2014] [Indexed: 01/13/2023]
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Vilches S, Vergara C, Nicolás O, Mata Á, Del Río JA, Gavín R. Domain-Specific Activation of Death-Associated Intracellular Signalling Cascades by the Cellular Prion Protein in Neuroblastoma Cells. Mol Neurobiol 2015; 53:4438-48. [PMID: 26250617 DOI: 10.1007/s12035-015-9360-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/13/2015] [Indexed: 10/23/2022]
Abstract
The biological functions of the cellular prion protein remain poorly understood. In fact, numerous studies have aimed to determine specific functions for the different protein domains. Studies of cellular prion protein (PrP(C)) domains through in vivo expression of molecules carrying internal deletions in a mouse Prnp null background have provided helpful data on the implication of the protein in signalling cascades in affected neurons. Nevertheless, understanding of the mechanisms underlying the neurotoxicity induced by these PrP(C) deleted forms is far from complete. To better define the neurotoxic or neuroprotective potential of PrP(C) N-terminal domains, and to overcome the heterogeneity of results due to the lack of a standardized model, we used neuroblastoma cells to analyse the effects of overexpressing PrP(C) deleted forms. Results indicate that PrP(C) N-terminal deleted forms were properly processed through the secretory pathway. However, PrPΔF35 and PrPΔCD mutants led to death by different mechanisms sharing loss of alpha-cleavage and activation of caspase-3. Our data suggest that both gain-of-function and loss-of-function pathogenic mechanisms may be associated with N-terminal domains and may therefore contribute to neurotoxicity in prion disease. Dissecting the molecular response induced by PrPΔF35 may be the key to unravelling the physiological and pathological functions of the prion protein.
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Affiliation(s)
- Silvia Vilches
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Cristina Vergara
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Oriol Nicolás
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Ágata Mata
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - José A Del Río
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain. .,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain.
| | - Rosalina Gavín
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain. .,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain.
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31
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Haigh CL, McGlade AR, Collins SJ. MEK1 transduces the prion protein N2 fragment antioxidant effects. Cell Mol Life Sci 2015; 72:1613-29. [PMID: 25391659 PMCID: PMC11114014 DOI: 10.1007/s00018-014-1777-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 10/13/2014] [Accepted: 11/06/2014] [Indexed: 10/24/2022]
Abstract
The prion protein (PrP(C)) when mis-folded is causally linked with a group of fatal neurodegenerative diseases called transmissible spongiform encephalopathies or prion diseases. PrP(C) normal function is still incompletely defined with such investigations complicated by PrP(C) post-translational modifications, such as internal cleavage, which feasibly could change, activate, or deactivate the function of this protein. Oxidative stress induces β-cleavage and the N-terminal product of this cleavage event, N2, demonstrates a cellular protective response against oxidative stress. The mechanisms by which N2 mediates cellular antioxidant protection were investigated within an in vitro cell model. N2 protection was regulated by copper binding to the octarepeat domain, directing the route of internalisation, which stimulated MEK1 signalling. Precise membrane interactions of N2, determined by copper saturation, and involving both the copper-co-ordinating octarepeat region and the structure conferred upon the N-terminal polybasic region by the proline motif, were essential for the correct engagement of this pathway. The phenomenon of PrP(C) post-translational modification, such as cleavage and copper co-ordination, as a molecular "switch" for activation or deactivation of certain functions provides new insight into the apparent multi-functionality of PrP(C).
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Affiliation(s)
- C. L. Haigh
- Department of Pathology, Melbourne Brain Centre, The University of Melbourne, Parkville, Melbourne, 3010 Australia
| | - A. R. McGlade
- Department of Pathology, Melbourne Brain Centre, The University of Melbourne, Parkville, Melbourne, 3010 Australia
- Mental Health Research Institute, The University of Melbourne, Parkville, Melbourne, 3010 Australia
| | - S. J. Collins
- Department of Pathology, Melbourne Brain Centre, The University of Melbourne, Parkville, Melbourne, 3010 Australia
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC 3010 Australia
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32
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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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33
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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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Abstract
Mutations within the central region of prion protein (PrP) have been shown to be associated with severe neurotoxic activity similar to that observed with Dpl, a PrP-like protein. To further investigate this neurotoxic effect, we generated lines of transgenic (Tg) mice expressing three different chimeric PrP-Dpl proteins. Chi1 (amino acids 1-57 of Dpl replaced by amino acids 1-125 of PrP) and Chi2 (amino acids 1-66 of Dpl replaced by amino acids 1-134 of PrP) abrogated the pathogenicity of Dpl indicating that the presence of a N-terminal domain of PrP (23-134) reduced the toxicity of Dpl, as reported. However, when the amino acids 1-24 of Dpl were replaced by amino acids 1-124 of PrP, Chi3 Tg mice, which express the chimeric protein at a very low level, start developing ataxia at the age of 5-7 weeks. This phenotype was not counteracted by a single copy of full-length-PrP(c) but rather by its overexpression, indicating the strong toxicity of the chimeric protein Chi3. Chi3 Tg mice exhibit severe cerebellar atrophy with a significant loss of granule cells. We concluded that aa25 to aa57 of Dpl, which are not present in Chi1 and Chi2 constructs, confer toxicity to the protein. We tested this possibility by using the 25-57 Dpl peptide in primary culture of mouse embryo cortical neurons and found a significant neurotoxic effect. This finding identifies a protein domain that plays a role in mediating Dpl-related toxicity.
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35
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Abstract
The events leading to the degradation of the endogenous PrP(C) (normal cellular prion protein) have been the subject of numerous studies. Two cleavage processes, α-cleavage and β-cleavage, are responsible for the main C- and N-terminal fragments produced from PrP(C). Both cleavage processes occur within the N-terminus of PrP(C), a region that is significant in terms of function. α-Cleavage, an enzymatic event that occurs at amino acid residues 110 and 111 on PrP(C), interferes with the conversion of PrP(C) into the prion disease-associated isoform, PrP(Sc) (abnormal disease-specific conformation of prion protein). This processing is seen as a positive event in terms of disease development. The study of β-cleavage has taken some surprising turns. β-Cleavage is brought about by ROS (reactive oxygen species). The C-terminal fragment produced, C2, may provide the seed for the abnormal conversion process, as it resembles in size the fragments isolated from prion-infected brains. There is, however, strong evidence that β-cleavage provides an essential process to reduce oxidative stress. β-Cleavage may act as a double-edged sword. By β-cleavage, PrP(C) may try to balance the ROS levels produced during prion infection, but the C2 produced may provide a PrP(Sc) seed that maintains the prion conversion process.
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Abstract
The human cellular prion protein (PrP(C)) is a glycosylphosphatidylinositol (GPI) anchored membrane glycoprotein with two N-glycosylation sites at residues 181 and 197. This protein migrates in several bands by Western blot analysis (WB). Interestingly, PNGase F treatment of human brain homogenates prior to the WB, which is known to remove the N-glycosylations, unexpectedly gives rise to two dominant bands, which are now known as C-terminal (C1) and N-terminal (N1) fragments. This resembles the β-amyloid precursor protein (APP) in Alzheimer disease (AD), which can be physiologically processed by α-, β-, and γ-secretases. The processing of APP has been extensively studied, while the identity of the cellular proteases involved in the proteolysis of PrP(C) and their possible role in prion biology has remained limited and controversial. Nevertheless, there is a strong correlation between the neurotoxicity caused by prion proteins and the blockade of their normal proteolysis. For example, expression of non-cleavable PrP(C) mutants in transgenic mice generates neurotoxicity, even in the absence of infectious prions, suggesting that PrP(C) proteolysis is physiologically and pathologically important. As many mouse models of prion diseases have recently been developed and the knowledge about the proteases responsible for the PrP(C) proteolysis is accumulating, we examine the historical experimental evidence and highlight recent studies that shed new light on this issue.
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The N-terminal, polybasic region of PrP(C) dictates the efficiency of prion propagation by binding to PrP(Sc). J Neurosci 2012; 32:8817-30. [PMID: 22745483 DOI: 10.1523/jneurosci.1103-12.2012] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Prion propagation involves a templating reaction in which the infectious form of the prion protein (PrP(Sc)) binds to the cellular form (PrP(C)), generating additional molecules of PrP(Sc). While several regions of the PrP(C) molecule have been suggested to play a role in PrP(Sc) formation based on in vitro studies, the contribution of these regions in vivo is unclear. Here, we report that mice expressing PrP deleted for a short, polybasic region at the N terminus (residues 23-31) display a dramatically reduced susceptibility to prion infection and accumulate greatly reduced levels of PrP(Sc). These results, in combination with biochemical data, demonstrate that residues 23-31 represent a critical site on PrP(C) that binds to PrP(Sc) and is essential for efficient prion propagation. It may be possible to specifically target this region for treatment of prion diseases as well as other neurodegenerative disorders due to β-sheet-rich oligomers that bind to PrP(C).
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Nakamura Y, Nakazawa K, Hamasaki K. Host–Guest-bridge Induces Irreversible Helix Folding in a Short Peptide. CHEM LETT 2012. [DOI: 10.1246/cl.2012.908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yuki Nakamura
- Department of Applied Chemistry, Shibaura Institute of Technology
| | - Kazuya Nakazawa
- Department of Applied Chemistry, Shibaura Institute of Technology
| | - Keita Hamasaki
- Department of Applied Chemistry, Shibaura Institute of Technology
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Wisniewski T, Goñi F. Could immunomodulation be used to prevent prion diseases? Expert Rev Anti Infect Ther 2012; 10:307-17. [PMID: 22397565 DOI: 10.1586/eri.11.177] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
All prion diseases are currently without effective treatment and are universally fatal. The underlying pathogenesis of prion diseases (prionoses) is related to an autocatalytic conformational conversion of PrP(C) (C for cellular) to a pathological and infectious conformer known as PrP(Sc) (Sc for scrapie) or PrP(Res) (Res for proteinase K resistant). The past experience with variant Creutzfeldt-Jakob disease, which originated from bovine spongiform encephalopathy, as well as the ongoing epidemic of chronic wasting disease has highlighted the necessity for effective prophylactic and/or therapeutic approaches. Human prionoses are most commonly sporadic, and hence therapy is primarily directed to stop progression; however, in animals the majority of prionoses are infectious and, as a result, the emphasis is on prevention of transmission. These infectious prionoses are most commonly acquired via the alimentary tract as a major portal of infectious agent entry, making mucosal immunization a potentially attractive method to produce a local immune response that can partially or completely prevent prion entry across the gut barrier, while at the same time producing a modulated systemic immunity that is unlikely to be associated with toxicity. A critical factor in any immunomodulatory methodology that targets a self-antigen is the need to delicately balance an effective humoral immune response with potential autoimmune inflammatory toxicity. The ongoing epidemic of chronic wasting disease affecting the USA and Korea, with the potential to spread to human populations, highlights the need for such immunomodulatory approaches.
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Affiliation(s)
- Thomas Wisniewski
- New York University School of Medicine, 560 First Avenue, New York, NY 10016, USA.
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Affiliation(s)
- Adriano Aguzzi
- Institute of Neuropathology, University Hospital of Zürich, Switzerland.
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Biasini E, Turnbaugh JA, Massignan T, Veglianese P, Forloni G, Bonetto V, Chiesa R, Harris DA. The toxicity of a mutant prion protein is cell-autonomous, and can be suppressed by wild-type prion protein on adjacent cells. PLoS One 2012; 7:e33472. [PMID: 22428057 PMCID: PMC3299791 DOI: 10.1371/journal.pone.0033472] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 02/09/2012] [Indexed: 12/25/2022] Open
Abstract
Insight into the normal function of PrPC, and how it can be subverted to produce neurotoxic effects, is provided by PrP molecules carrying deletions encompassing the conserved central region. The most neurotoxic of these mutants, Δ105–125 (called ΔCR), produces a spontaneous neurodegenerative illness when expressed in transgenic mice, and this phenotype can be dose-dependently suppressed by co-expression of wild-type PrP. Whether the toxic activity of ΔCR PrP and the protective activity or wild-type PrP are cell-autonomous, or can be exerted on neighboring cells, is unknown. To investigate this question, we have utilized co-cultures of differentiated neural stem cells derived from mice expressing ΔCR or wild-type PrP. Cells from the two kinds of mice, which are marked by the presence or absence of GFP, are differentiated together to yield neurons, astrocytes, and oligodendrocytes. As a surrogate read-out of ΔCR PrP toxicity, we assayed sensitivity of the cells to the cationic antibiotic, Zeocin. In a previous study, we reported that cells expressing ΔCR PrP are hypersensitive to the toxic effects of several cationic antibiotics, an effect that is suppressed by co-expression of wild type PrP, similar to the rescue of the neurodegenerative phenotype observed in transgenic mice. Using this system, we find that while ΔCR-dependent toxicity is cell-autonomous, the rescuing activity of wild-type PrP can be exerted in trans from nearby cells. These results provide important insights into how ΔCR PrP subverts a normal physiological function of PrPC, and the cellular mechanisms underlying the rescuing process.
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Affiliation(s)
- Emiliano Biasini
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Dulbecco Telethon Institute, Milan, Italy
- Department of Neuroscience, Mario Negri Institute, Milan, Italy
- * E-mail: (EB); (DAH)
| | - Jessie A. Turnbaugh
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Tania Massignan
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Dulbecco Telethon Institute, Milan, Italy
- Department of Biochemistry and Molecular Pharmacology, Mario Negri Institute, Milan, Italy
| | | | | | - Valentina Bonetto
- Dulbecco Telethon Institute, Milan, Italy
- Department of Biochemistry and Molecular Pharmacology, Mario Negri Institute, Milan, Italy
| | - Roberto Chiesa
- Dulbecco Telethon Institute, Milan, Italy
- Department of Neuroscience, Mario Negri Institute, Milan, Italy
| | - David A. Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail: (EB); (DAH)
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Watt NT, Taylor DR, Kerrigan TL, Griffiths HH, Rushworth JV, Whitehouse IJ, Hooper NM. Prion protein facilitates uptake of zinc into neuronal cells. Nat Commun 2012; 3:1134. [PMID: 23072804 PMCID: PMC3493655 DOI: 10.1038/ncomms2135] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/14/2012] [Indexed: 12/30/2022] Open
Abstract
Zinc is released into the synaptic cleft upon exocytotic stimuli, although the mechanism for its reuptake into neurons is unresolved. Here we show that the cellular prion protein enhances the uptake of zinc into neuronal cells. This prion-protein-mediated zinc influx requires the octapeptide repeats and amino-terminal polybasic region in the prion protein, but not its endocytosis. Selective antagonists of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors block the prion protein-mediated zinc uptake, and the prion protein co-immunoprecipitates with both GluA1 and GluA2 AMPA receptor subunits. Zinc-sensitive intracellular tyrosine phosphatase activity is decreased in cells expressing prion protein and increased in the brains of prion-protein-null mice, providing evidence of a physiological consequence of this process. Prion protein-mediated zinc uptake is ablated in cells expressing familial associated mutants of the protein and in prion-infected cells. These data suggest that alterations in the cellular prion protein-mediated zinc uptake may contribute to neurodegeneration in prion and other neurodegenerative diseases.
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Affiliation(s)
- Nicole T. Watt
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - David R. Taylor
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Talitha L. Kerrigan
- Division of Cardiovascular and Neuronal Remodelling, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds LS2 9JT, UK
- Present address: Faculty of Medicine and Dentistry, Henry Wellcome LINE and MRC Centre for Synaptic Plasticity, University of Bristol, Bristol BS1 3NY, UK
| | - Heledd H. Griffiths
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Jo V. Rushworth
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Isobel J. Whitehouse
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Nigel M. Hooper
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
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Prion protein at the crossroads of physiology and disease. Trends Neurosci 2011; 35:92-103. [PMID: 22137337 DOI: 10.1016/j.tins.2011.10.002] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 10/20/2011] [Accepted: 10/20/2011] [Indexed: 11/23/2022]
Abstract
The presence of the cellular prion protein (PrP(C)) on the cell surface is critical for the neurotoxicity of prions. Although several biological activities have been attributed to PrP(C), a definitive demonstration of its physiological function remains elusive. In this review, we discuss some of the proposed functions of PrP(C), focusing on recently suggested roles in cell adhesion, regulation of ionic currents at the cell membrane and neuroprotection. We also discuss recent evidence supporting the idea that PrP(C) may function as a receptor for soluble oligomers of the amyloid β peptide and possibly other toxic protein aggregates. These data suggest surprising new connections between the physiological function of PrP(C) and its role in neurodegenerative diseases beyond those caused by prions.
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Westergard L, Turnbaugh JA, Harris DA. A naturally occurring C-terminal fragment of the prion protein (PrP) delays disease and acts as a dominant-negative inhibitor of PrPSc formation. J Biol Chem 2011; 286:44234-44242. [PMID: 22025612 DOI: 10.1074/jbc.m111.286195] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cellular prion protein (PrPC) undergoes constitutive proteolytic cleavage between residues 111/112 to yield a soluble N-terminal fragment (N1) and a membrane-anchored C-terminal fragment (C1). The C1 fragment represents the major proteolytic fragment of PrPC in brain and several cell types. To explore the role of C1 in prion disease, we generated Tg(C1) transgenic mice expressing this fragment (PrP(Δ23-111)) in the presence and absence of endogenous PrP. In contrast to several other N-terminally deleted forms of PrP, the C1 fragment does not cause a spontaneous neurological disease in the absence of endogenous PrP. Tg(C1) mice inoculated with scrapie prions remain healthy and do not accumulate protease-resistant PrP, demonstrating that C1 is not a substrate for conversion to PrPSc (the disease-associated isoform). Interestingly, Tg(C1) mice co-expressing C1 along with wild-type PrP (either endogenous or encoded by a second transgene) become ill after scrapie inoculation, but with a dramatically delayed time course compared with mice lacking C1. In addition, accumulation of PrPSc was markedly slowed in these animals. Similar effects were produced by a shorter C-terminal fragment of PrP(Δ23-134). These results demonstrate that C1 acts as dominant-negative inhibitor of PrPSc formation and accumulation of neurotoxic forms of PrP. Thus, C1, a naturally occurring fragment of PrPC, might play a modulatory role during the course of prion diseases. In addition, enhancing production of C1, or exogenously administering this fragment, represents a potential therapeutic strategy for the treatment of prion diseases.
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Affiliation(s)
- Laura Westergard
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jessie A Turnbaugh
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118.
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Turnbaugh JA, Westergard L, Unterberger U, Biasini E, Harris DA. The N-terminal, polybasic region is critical for prion protein neuroprotective activity. PLoS One 2011; 6:e25675. [PMID: 21980526 PMCID: PMC3183058 DOI: 10.1371/journal.pone.0025675] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/09/2011] [Indexed: 11/19/2022] Open
Abstract
Several lines of evidence suggest that the normal form of the prion protein, PrP(C), exerts a neuroprotective activity against cellular stress or toxicity. One of the clearest examples of such activity is the ability of wild-type PrP(C) to suppress the spontaneous neurodegenerative phenotype of transgenic mice expressing a deleted form of PrP (Δ32-134, called F35). To define domains of PrP involved in its neuroprotective activity, we have analyzed the ability of several deletion mutants of PrP (Δ23-31, Δ23-111, and Δ23-134) to rescue the phenotype of Tg(F35) mice. Surprisingly, all of these mutants displayed greatly diminished rescue activity, although Δ23-31 PrP partially suppressed neuronal loss when expressed at very high levels. Our results pinpoint the N-terminal, polybasic domain as a critical determinant of PrP(C) neuroprotective activity, and suggest that identification of molecules interacting with this region will provide important clues regarding the normal function of the protein. Small molecule ligands targeting this region may also represent useful therapeutic agents for treatment of prion diseases.
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Affiliation(s)
- Jessie A. Turnbaugh
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Department of Cell Biology and Physiology Washington University School of Medicine St. Louis, St. Louis, Missouri, United States of America
| | - Laura Westergard
- Department of Cell Biology and Physiology Washington University School of Medicine St. Louis, St. Louis, Missouri, United States of America
| | - Ursula Unterberger
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Emiliano Biasini
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - David A. Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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