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Banik P, Ray K, Kamps J, Chen QY, Luesch H, Winklhofer KF, Tatzelt J. VCP/p97 mediates nuclear targeting of non-ER-imported prion protein to maintain proteostasis. Life Sci Alliance 2024; 7:e202302456. [PMID: 38570188 PMCID: PMC10992997 DOI: 10.26508/lsa.202302456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024] Open
Abstract
Mistargeting of secretory proteins in the cytosol can trigger their aggregation and subsequent proteostasis decline. We have identified a VCP/p97-dependent pathway that directs non-ER-imported prion protein (PrP) into the nucleus to prevent the formation of toxic aggregates in the cytosol. Upon impaired translocation into the ER, PrP interacts with VCP/p97, which facilitates nuclear import mediated by importin-ß. Notably, the cytosolic interaction of PrP with VCP/p97 and its nuclear import are independent of ubiquitination. In vitro experiments revealed that VCP/p97 binds non-ubiquitinated PrP and prevents its aggregation. Inhibiting binding of PrP to VCP/p97, or transient proteotoxic stress, promotes the formation of self-perpetuating and partially proteinase resistant PrP aggregates in the cytosol, which compromised cellular proteostasis and disrupted further nuclear targeting of PrP. In the nucleus, RNAs keep PrP in a soluble and non-toxic conformation. Our study revealed a novel ubiquitin-independent role of VCP/p97 in the nuclear targeting of non-imported secretory proteins and highlights the impact of the chemical milieu in triggering protein misfolding.
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Affiliation(s)
- Papiya Banik
- https://ror.org/04tsk2644 Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Koustav Ray
- https://ror.org/04tsk2644 Department Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Janine Kamps
- https://ror.org/04tsk2644 Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
- Cluster of Excellence RESOLV, Bochum, Germany
| | - Qi-Yin Chen
- https://ror.org/02y3ad647 Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL, USA
| | - Hendrik Luesch
- https://ror.org/02y3ad647 Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL, USA
| | - Konstanze F Winklhofer
- https://ror.org/04tsk2644 Department Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
- Cluster of Excellence RESOLV, Bochum, Germany
| | - Jörg Tatzelt
- https://ror.org/04tsk2644 Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
- Cluster of Excellence RESOLV, Bochum, Germany
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2
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Polido SA, Stuani C, Voigt A, Banik P, Kamps J, Bader V, Grover P, Krause LJ, Zerr I, Matschke J, Glatzel M, Winklhofer KF, Buratti E, Tatzelt J. Cross-seeding by prion protein inactivates TDP-43. Brain 2024; 147:240-254. [PMID: 37669322 DOI: 10.1093/brain/awad289] [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: 01/30/2023] [Revised: 07/14/2023] [Accepted: 08/03/2023] [Indexed: 09/07/2023] Open
Abstract
A common pathological denominator of various neurodegenerative diseases is the accumulation of protein aggregates. Neurotoxic effects are caused by a loss of the physiological activity of the aggregating protein and/or a gain of toxic function of the misfolded protein conformers. In transmissible spongiform encephalopathies or prion diseases, neurodegeneration is caused by aberrantly folded isoforms of the prion protein (PrP). However, it is poorly understood how pathogenic PrP conformers interfere with neuronal viability. Employing in vitro approaches, cell culture, animal models and patients' brain samples, we show that misfolded PrP can induce aggregation and inactivation of TAR DNA-binding protein-43 (TDP-43). Purified PrP aggregates interact with TDP-43 in vitro and in cells and induce the conversion of soluble TDP-43 into non-dynamic protein assemblies. Similarly, mislocalized PrP conformers in the cytosol bind to and sequester TDP-43 in cytosolic aggregates. As a consequence, TDP-43-dependent splicing activity in the nucleus is significantly decreased, leading to altered protein expression in cells with cytosolic PrP aggregates. Finally, we present evidence for cytosolic TDP-43 aggregates in neurons of transgenic flies expressing mammalian PrP and Creutzfeldt-Jakob disease patients. Our study identified a novel mechanism of how aberrant PrP conformers impair physiological pathways by cross-seeding.
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Affiliation(s)
- Stella A Polido
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Cristiana Stuani
- International Centre for Genetic Engineering and Biotechnology (ICGEB), 34149 Trieste, Italy
| | - Aaron Voigt
- Department of Neurology, Medical Faculty, University Hospital, RWTH Aachen University, 52074 Aachen, Germany
| | - Papiya Banik
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Janine Kamps
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
| | - Verian Bader
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Prerna Grover
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Laura J Krause
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Inga Zerr
- Department of Neurology, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Jakob Matschke
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Markus Glatzel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Konstanze F Winklhofer
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology (ICGEB), 34149 Trieste, Italy
| | - Jörg Tatzelt
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
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Amyloid Cross-Seeding: Mechanism, Implication, and Inhibition. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27061776. [PMID: 35335141 PMCID: PMC8955620 DOI: 10.3390/molecules27061776] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 01/21/2023]
Abstract
Most neurodegenerative diseases such as Alzheimer’s disease, type 2 diabetes, Parkinson’s disease, etc. are caused by inclusions and plaques containing misfolded protein aggregates. These protein aggregates are essentially formed by the interactions of either the same (homologous) or different (heterologous) sequences. Several experimental pieces of evidence have revealed the presence of cross-seeding in amyloid proteins, which results in a multicomponent assembly; however, the molecular and structural details remain less explored. Here, we discuss the amyloid proteins and the cross-seeding phenomena in detail. Data suggest that targeting the common epitope of the interacting amyloid proteins may be a better therapeutic option than targeting only one species. We also examine the dual inhibitors that target the amyloid proteins participating in the cross-seeding events. The future scopes and major challenges in understanding the mechanism and developing therapeutics are also considered. Detailed knowledge of the amyloid cross-seeding will stimulate further research in the practical aspects and better designing anti-amyloid therapeutics.
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4
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Panes JD, Saavedra P, Pineda B, Escobar K, Cuevas ME, Moraga-Cid G, Fuentealba J, Rivas CI, Rezaei H, Muñoz-Montesino C. PrP C as a Transducer of Physiological and Pathological Signals. Front Mol Neurosci 2021; 14:762918. [PMID: 34880726 PMCID: PMC8648500 DOI: 10.3389/fnmol.2021.762918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/18/2021] [Indexed: 11/13/2022] Open
Abstract
After the discovery of prion phenomenon, the physiological role of the cellular prion protein (PrP C ) remained elusive. In the past decades, molecular and cellular analysis has shed some light regarding interactions and functions of PrP C in health and disease. PrP C , which is located mainly at the plasma membrane of neuronal cells attached by a glycosylphosphatidylinositol (GPI) anchor, can act as a receptor or transducer from external signaling. Although the precise role of PrP C remains elusive, a variety of functions have been proposed for this protein, namely, neuronal excitability and viability. Although many issues must be solved to clearly define the role of PrP C , its connection to the central nervous system (CNS) and to several misfolding-associated diseases makes PrP C an interesting pharmacological target. In a physiological context, several reports have proposed that PrP C modulates synaptic transmission, interacting with various proteins, namely, ion pumps, channels, and metabotropic receptors. PrP C has also been implicated in the pathophysiological cell signaling induced by β-amyloid peptide that leads to synaptic dysfunction in the context of Alzheimer's disease (AD), as a mediator of Aβ-induced cell toxicity. Additionally, it has been implicated in other proteinopathies as well. In this review, we aimed to analyze the role of PrP C as a transducer of physiological and pathological signaling.
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Affiliation(s)
- Jessica D Panes
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Paulina Saavedra
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Benjamin Pineda
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Kathleen Escobar
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Magdalena E Cuevas
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Gustavo Moraga-Cid
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Jorge Fuentealba
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Coralia I Rivas
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Human Rezaei
- Virologie et Immunologie Moléculaires (VIM), Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Jouy-en-Josas, France.,Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Versailles, France.,Université Paris-Saclay, Jouy-en-Josas, France
| | - Carola Muñoz-Montesino
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
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5
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Gielnik M, Taube M, Zhukova L, Zhukov I, Wärmländer SKTS, Svedružić Ž, Kwiatek WM, Gräslund A, Kozak M. Zn(II) binding causes interdomain changes in the structure and flexibility of the human prion protein. Sci Rep 2021; 11:21703. [PMID: 34737343 PMCID: PMC8568922 DOI: 10.1038/s41598-021-00495-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 10/05/2021] [Indexed: 12/31/2022] Open
Abstract
The cellular prion protein (PrPC) is a mainly α-helical 208-residue protein located in the pre- and postsynaptic membranes. For unknown reasons, PrPC can undergo a structural transition into a toxic, β-sheet rich scrapie isoform (PrPSc) that is responsible for transmissible spongiform encephalopathies (TSEs). Metal ions seem to play an important role in the structural conversion. PrPC binds Zn(II) ions and may be involved in metal ion transport and zinc homeostasis. Here, we use multiple biophysical techniques including optical and NMR spectroscopy, molecular dynamics simulations, and small angle X-ray scattering to characterize interactions between human PrPC and Zn(II) ions. Binding of a single Zn(II) ion to the PrPC N-terminal domain via four His residues from the octarepeat region induces a structural transition in the C-terminal α-helices 2 and 3, promotes interaction between the N-terminal and C-terminal domains, reduces the folded protein size, and modifies the internal structural dynamics. As our results suggest that PrPC can bind Zn(II) under physiological conditions, these effects could be important for the physiological function of PrPC.
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Affiliation(s)
- Maciej Gielnik
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614, Poznań, Poland
| | - Michał Taube
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614, Poznań, Poland
| | - Lilia Zhukova
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106, Warszawa, Poland
| | - Igor Zhukov
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106, Warszawa, Poland
| | | | - Željko Svedružić
- Department of Biotechnology, University of Rijeka, 51000, Rijeka, Croatia
| | - Wojciech M Kwiatek
- Institute of Nuclear Physics Polish Academy of Sciences, 31-342, Kraków, Poland
| | - Astrid Gräslund
- Department of Biochemistry and Biophysics, Stockholm University, 10691, Stockholm, Sweden
| | - Maciej Kozak
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, 61-614, Poznań, Poland.
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, 30-392, Kraków, Poland.
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6
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A New Take on Prion Protein Dynamics in Cellular Trafficking. Int J Mol Sci 2020; 21:ijms21207763. [PMID: 33092231 PMCID: PMC7589859 DOI: 10.3390/ijms21207763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/14/2020] [Accepted: 10/14/2020] [Indexed: 12/12/2022] Open
Abstract
The mobility of cellular prion protein (PrPC) in specific cell membrane domains and among distinct cell compartments dictates its molecular interactions and directs its cell function. PrPC works in concert with several partners to organize signaling platforms implicated in various cellular processes. The scaffold property of PrPC is able to gather a molecular repertoire to create heterogeneous membrane domains that favor endocytic events. Dynamic trafficking of PrPC through multiple pathways, in a well-orchestrated mechanism of intra and extracellular vesicular transport, defines its functional plasticity, and also assists the conversion and spreading of its infectious isoform associated with neurodegenerative diseases. In this review, we highlight how PrPC traffics across intra- and extracellular compartments and the consequences of this dynamic transport in governing cell functions and contributing to prion disease pathogenesis.
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7
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Gonsberg A, Jung S, Ulbrich S, Origi A, Ziska A, Baier M, Koch HG, Zimmermann R, Winklhofer KF, Tatzelt J. The Sec61/SecY complex is inherently deficient in translocating intrinsically disordered proteins. J Biol Chem 2017; 292:21383-21396. [PMID: 29084847 DOI: 10.1074/jbc.m117.788067] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 10/26/2017] [Indexed: 11/06/2022] Open
Abstract
About one-quarter to nearly one-third of the proteins synthesized in the cytosol of eukaryotic cells are integrated into the plasma membrane or are secreted. Translocation of secretory proteins into the lumen of the endoplasmic reticulum or the periplasm of bacteria is mediated by a highly conserved heterotrimeric membrane protein complex denoted Sec61 in eukaryotes and SecYEG in bacteria. To evaluate a possible modulation of the translocation efficiency by secondary structures of the nascent peptide chain, we performed a comparative analysis in bacteria, yeast, and mammalian cells. Strikingly, neither the bacterial SecY nor the eukaryotic Sec61 translocon was able to efficiently transport proteins entirely composed of intrinsically disordered domains (IDDs) or β-strands. However, translocation could be restored by α-helical domains in a position- and organism-dependent manner. In bacteria, we found that the α-helical domains have to precede the IDD or β-strands, whereas in mammalian cells, C-terminally located α-helical domains are sufficient to promote translocation. Our study reveals an evolutionarily conserved deficiency of the Sec61/SecY complex to translocate IDDs and β-strands in the absence of α-helical domains. Moreover, our results may suggest that adaptive pathways co-evolved with the expansion of IDDs in the proteome of eukaryotic cells to increase the transport capacity of the Sec61 translocon.
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Affiliation(s)
- Anika Gonsberg
- From the Departments of Biochemistry of Neurodegenerative Diseases and
| | - Sebastian Jung
- From the Departments of Biochemistry of Neurodegenerative Diseases and
| | - Sarah Ulbrich
- From the Departments of Biochemistry of Neurodegenerative Diseases and
| | - Andrea Origi
- the Institute of Biochemistry and Molecular Biology, Faculty of Medicine, Albert-Ludwigs-University Freiburg, D-79104 Freiburg im Breisgau, Germany
| | - Anke Ziska
- the Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66421 Homburg, Germany, and
| | - Michael Baier
- the Research Group Proteinopathies/Neurodegenerative Diseases, Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, D-13353 Berlin, Germany
| | - Hans-Georg Koch
- the Institute of Biochemistry and Molecular Biology, Faculty of Medicine, Albert-Ludwigs-University Freiburg, D-79104 Freiburg im Breisgau, Germany
| | - Richard Zimmermann
- the Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66421 Homburg, Germany, and
| | - Konstanze F Winklhofer
- Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44801 Bochum, Germany
| | - Jörg Tatzelt
- From the Departments of Biochemistry of Neurodegenerative Diseases and
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8
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Sarnataro D, Pepe A, Zurzolo C. Cell Biology of Prion Protein. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2017; 150:57-82. [PMID: 28838675 DOI: 10.1016/bs.pmbts.2017.06.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cellular prion protein (PrPC) is a mammalian glycoprotein which is usually found anchored to the plasma membrane via a glycosylphosphatidylinositol (GPI) anchor. The precise function of PrPC remains elusive but may depend upon its cellular localization. PrPC misfolds to a pathogenic isoform PrPSc, the causative agent of neurodegenerative prion diseases. Nonetheless some forms of prion disease develop in the apparent absence of infectious PrPSc, suggesting that molecular species of PrP distinct from PrPSc may represent the primary neurotoxic culprits. Indeed, in some inherited cases of human prion disease, the predominant form of PrP detectable in the brain is not PrPSc but rather CtmPrP, a transmembrane form of the protein. The relationship between the neurodegeneration occurring in prion diseases involving PrPSc and that associated with CtmPrP remains unclear. However, the different membrane topology of the PrP mutants, as well as the presence of the GPI anchor, could influence both the function and the intracellular localization and trafficking of the protein, all being potentially very important in the pathophysiological mechanism that ultimately causes the disease. Here, we review the latest findings on the fundamental aspects of prions biology, from the PrPC biosynthesis, function, and structure up to its intracellular traffic and analyze the possible roles of the different topological isoforms of the protein, as well as the GPI anchor, in the pathogenesis of the disease.
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Affiliation(s)
- Daniela Sarnataro
- University of Naples "Federico II", Naples, Italy; Ceinge-Biotecnologie avanzate, s.c.a r.l., Naples, Italy.
| | - Anna Pepe
- University of Naples "Federico II", Naples, Italy; Unité de Trafic Membranaire et Pathogenese, Institut Pasteur, Paris, France
| | - Chiara Zurzolo
- University of Naples "Federico II", Naples, Italy; Unité de Trafic Membranaire et Pathogenese, Institut Pasteur, Paris, France
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9
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Kretzschmar H, Tatzelt J. Prion disease: a tale of folds and strains. Brain Pathol 2013; 23:321-32. [PMID: 23587138 DOI: 10.1111/bpa.12045] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 02/04/2013] [Indexed: 12/31/2022] Open
Abstract
Research on prions, the infectious agents of devastating neurological diseases in humans and animals, has been in the forefront of developing the concept of protein aggregation diseases. Prion diseases are distinguished from other neurodegenerative diseases by three peculiarities. First, prion diseases, in addition to being sporadic or genetic like all other neurodegenerative diseases, are infectious diseases. Animal models were developed early on (a long time before the advent of transgenic technology), and this has made possible the discovery of the prion protein as the infectious agent. Second, human prion diseases have true equivalents in animals, such as scrapie, which has been the subject of experimental research for many years. Variant Creutzfeldt-Jakob disease (vCJD) is a zoonosis caused by bovine spongiform encephalopathy (BSE) prions. Third, they show a wide variety of phenotypes in humans and animals, much wider than the variants of any other sporadic or genetic neurodegenerative disease. It has now become firmly established that particular PrP(Sc) isoforms are closely related to specific human prion strains. The variety of human prion diseases, still an enigma in its own right, is a focus of this article. Recently, a series of experiments has shown that the concept of aberrant protein folding and templating, first developed for prions, may apply to a variety of neurodegenerative diseases. In the wake of these discoveries, the term prion has come to be used for Aβ, α-synuclein, tau and possibly others. The self-propagation of alternative conformations seems to be the common denominator of these "prions," which in future, in order to avoid confusion, may have to be specified either as "neurodegenerative prions" or "infectious prions."
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10
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Lin Z, Zhao D, Yang L. Interaction between misfolded PrP and the ubiquitin-proteasome system in prion-mediated neurodegeneration. Acta Biochim Biophys Sin (Shanghai) 2013; 45:477-84. [PMID: 23449072 DOI: 10.1093/abbs/gmt020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Prion diseases are associated with the conformational conversion of cellular prion protein (PrP(C)) to pathological β-sheet isoforms (PrP(Sc)), which is the infectious agent beyond comprehension. Increasing evidence indicated that an unknown toxic gain of function of PrP(sc) underlies neuronal death. Conversely, strong evidence indicated that cellular prion protein might be directly cytotoxic by mediating neurotoxic signaling of β-sheet-rich conformers independent of prion replication. Furthermore, the common properties of β-sheet-rich isoform such as PrP(Sc) and β amyloid protein become the lynchpin that interprets the general pathological mechanism of protein misfolding diseases. Dysfunction of the ubiquitin-proteasome system (UPS) has been implicated in various protein misfolding diseases. However, the mechanisms of this impairment remain unknown in many cases. In prion disease, prion-infected mouse brains have increased levels of ubiquitin conjugates, which correlate with decreased proteasome function. Both PrP(C) and PrP(Sc) accumulate in cells after proteasome inhibition, which leads to increased cell death. A direct interaction between 20S core particle and PrP isoforms was demonstrated. Here we review the ability of misfolded PrP and UPS to affect each other, which might contribute to the pathological features of prion-mediated neurodegeneration.
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Affiliation(s)
- Zhu Lin
- State Key Laboratories for Agrobiotechnology, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
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11
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Abstract
Prion diseases in humans and animals are characterized by progressive neurodegeneration and the formation of infectious particles called prions. Both features are intimately linked to a conformational transition of the cellular prion protein (PrP(C)) into aberrantly folded conformers with neurotoxic and self-replicating activities. Interestingly, there is increasing evidence that the infectious and neurotoxic properties of PrP conformers are not necessarily coupled. Transgenic mouse models revealed that some PrP mutants interfere with neuronal function in the absence of infectious prions. Vice versa, propagation of prions can occur without causing neurotoxicity. Consequently, it appears plausible that two partially independent pathways exist, one pathway leading to the propagation of infectious prions and another one that mediates neurotoxic signaling. In this review we will summarize current knowledge of neurotoxic PrP conformers and discuss the role of PrP(C) as a mediator of both stress-protective and neurotoxic signaling cascades.
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12
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Seidel R, Engelhard M. Chemical biology of prion protein: tools to bridge the in vitro/vivo interface. Top Curr Chem (Cham) 2011; 305:199-223. [PMID: 21769714 DOI: 10.1007/128_2011_201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Research on prion protein (PrP) and pathogenic prion has been very intensive because of its importance as model system for neurodegenerative diseases. One important aspect of this research has been the application of chemical biology tools. In this review we describe new developments like native chemical ligation (NCL) and expressed protein ligation (EPL) for the synthesis and semisynthesis of proteins in general and PrP in particular. These techniques allow the synthesis of designed tailor made analogs which can be used in conjunction with modern biophysical methods like fluorescence spectroscopy, solid state Nuclear Magnetic Resonance (ssNMR), and Electron Paramagnetic Resonance (EPR). Another aspect of prion research is concerned with the interaction of PrP with small organic molecules and metals. The results are critically reviewed and put into perspective of their implication for PrP function.
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Affiliation(s)
- Ralf Seidel
- Max Planck Institut für Molekulare Physiologie, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
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13
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Schumacher MC, Resenberger U, Seidel RP, Becker CFW, Winklhofer KF, Oesterhelt D, Tatzelt J, Engelhard M. Synthesis of a GPI anchor module suitable for protein post-translational modification. Biopolymers 2010; 94:457-64. [DOI: 10.1002/bip.21380] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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14
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Singh N, Singh A, Das D, Mohan ML. Redox control of prion and disease pathogenesis. Antioxid Redox Signal 2010; 12:1271-94. [PMID: 19803746 PMCID: PMC2864664 DOI: 10.1089/ars.2009.2628] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 09/22/2009] [Accepted: 10/03/2009] [Indexed: 11/12/2022]
Abstract
Imbalance of brain metal homeostasis and associated oxidative stress by redox-active metals like iron and copper is an important trigger of neurotoxicity in several neurodegenerative conditions, including prion disorders. Whereas some reports attribute this to end-stage disease, others provide evidence for specific mechanisms leading to brain metal dyshomeostasis during disease progression. In prion disorders, imbalance of brain-iron homeostasis is observed before end-stage disease and worsens with disease progression, implicating iron-induced oxidative stress in disease pathogenesis. This is an unexpected observation, because the underlying cause of brain pathology in all prion disorders is PrP-scrapie (PrP(Sc)), a beta-sheet-rich conformation of a normal glycoprotein, the prion protein (PrP(C)). Whether brain-iron dyshomeostasis occurs because of gain of toxic function by PrP(Sc) or loss of normal function of PrP(C) remains unclear. In this review, we summarize available evidence suggesting the involvement of oxidative stress in prion-disease pathogenesis. Subsequently, we review the biology of PrP(C) to highlight its possible role in maintaining brain metal homeostasis during health and the contribution of PrP(Sc) in inducing brain metal imbalance with disease progression. Finally, we discuss possible therapeutic avenues directed at restoring brain metal homeostasis and alleviating metal-induced oxidative stress in prion disorders.
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Affiliation(s)
- Neena Singh
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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15
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Miesbauer M, Pfeiffer NV, Rambold AS, Müller V, Kiachopoulos S, Winklhofer KF, Tatzelt J. alpha-Helical domains promote translocation of intrinsically disordered polypeptides into the endoplasmic reticulum. J Biol Chem 2009; 284:24384-93. [PMID: 19561072 DOI: 10.1074/jbc.m109.023135] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Co-translational import into the endoplasmic reticulum (ER) is primarily controlled by N-terminal signal sequences that mediate targeting of the ribosome-nascent chain complex to the Sec61/translocon and initiate the translocation process. Here we show that after targeting to the translocon the secondary structure of the nascent polypeptide chain can significantly modulate translocation efficiency. ER-targeted polypeptides dominated by unstructured domains failed to efficiently translocate into the ER lumen and were subjected to proteasomal degradation via a co-translocational/preemptive pathway. Productive ER import could be reinstated by increasing the amount of alpha-helical domains, whereas more effective ER signal sequences had only a minor effect on ER import efficiency of unstructured polypeptides. ER stress and overexpression of p58(IPK) promoted the co-translocational degradation pathway. Moreover polypeptides with unstructured domains at their N terminus were specifically targeted to proteasomal degradation under these conditions. Our study indicates that extended unstructured domains are signals to dispose ER-targeted proteins via a co-translocational, preemptive quality control pathway.
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Affiliation(s)
- Margit Miesbauer
- Neurobiochemistry, Deutsches Zentrum für Neurodegenerative Erkrankungen and Adolf-Butenandt-Institut, Ludwig-Maximilians-Universität München, D-80336 München, Germany
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16
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Lund C, Olsen CM, Skogtvedt S, Tveit H, Prydz K, Tranulis MA. Alternative translation initiation generates cytoplasmic sheep prion protein. J Biol Chem 2009; 284:19668-78. [PMID: 19451655 DOI: 10.1074/jbc.m109.003566] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cytoplasmic localization of the prion protein (PrP) has been observed in different species and cell types. We have investigated this poorly understood phenomenon by expressing fusion proteins of sheep prion protein and green fluorescent protein ((GFP)PrP) in N2a cells, with variable sequence context surrounding the start codon Met(1). (GFP)PrP expressed with the wild-type sequence was transported normally through the secretory pathway to the cell surface with acquisition of N-glycan groups, but two N-terminal fragments of (GFP)PrP were detected intracellularly, starting in frame from Met(17). When (GFP)PrP was expressed with a compromised Kozak sequence ((GFP)PrP*), dispersed intracellular fluorescence was observed. A similar switch from pericellular to intracellular PrP localization was seen when analogous constructs of sheep PrP, without inserted GFP, were expressed, showing that this phenomenon is not caused by the GFP tag. Western blotting revealed a reduction in glycosylated forms of (GFP)PrP*, whereas the N-terminal fragments starting from Met(17) were still present. Formation of these N-terminal fragments was completely abolished when Met(17) was replaced by Thr, indicating that leaky ribosomal scanning occurs for normal sheep PrP and that translation from Met(17) is the cause of the aberrant cytoplasmic localization observed for a fraction of the protein. In contrast, the same phenomenon was not detected upon expression of similar constructs for mouse PrP. Analysis of samples from sheep brain allowed immunological detection of N-terminal PrP fragments, indicating that sheep PrP is subject to similar processing mechanisms in vivo.
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Affiliation(s)
- Christoffer Lund
- Institute of Basic Sciences and Aquatic Medicine, Department of Biochemistry and Physiology, Norwegian School of Veterinary Science, 0033 Oslo, Norway
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17
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Gilch S, Krammer C, Schätzl HM. Targeting prion proteins in neurodegenerative disease. Expert Opin Biol Ther 2008; 8:923-40. [PMID: 18549323 DOI: 10.1517/14712598.8.7.923] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Spongiform neurodegeneration is the pathological hallmark of individuals suffering from prion disease. These disorders, whose manifestation is sporadic, familial or acquired by infection, are caused by accumulation of the aberrantly folded isoform of the cellular prion protein (PrP(c)), termed PrP(Sc). Although usually rare, prion disorders are inevitably fatal and transferrable by infection. OBJECTIVE Pathology is restricted to the central nervous system and premortem diagnosis is usually not possible. Yet, promising approaches towards developing therapeutic regimens have been made recently. METHODS The biology of prion proteins and current models of neurotoxicity are discussed and prophylactic and therapeutic concepts are introduced. RESULTS/CONCLUSIONS Although various promising drug candidates with antiprion activity have been identified, this proof-of-concept cannot be transferred into translational medicine yet.
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Affiliation(s)
- Sabine Gilch
- Technische Universität München, Institute of Virology, Prion Research Group, Trogerstreet 30, 81675 Munich, Germany
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18
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Deriziotis P, Tabrizi SJ. Prions and the proteasome. Biochim Biophys Acta Mol Basis Dis 2008; 1782:713-22. [PMID: 18644436 DOI: 10.1016/j.bbadis.2008.06.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 06/23/2008] [Accepted: 06/24/2008] [Indexed: 10/21/2022]
Abstract
Prion diseases are fatal neurodegenerative disorders that include Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in animals. They are unique in terms of their biology because they are caused by the conformational re-arrangement of a normal host-encoded prion protein, PrPC, to an abnormal infectious isoform, PrPSc. Currently the precise mechanism behind prion-mediated neurodegeneration remains unclear. It is hypothesised than an unknown toxic gain of function of PrPSc, or an intermediate oligomeric form, underlies neuronal death. Increasing evidence suggests a role for the ubiquitin proteasome system (UPS) in prion disease. Both wild-type PrPC and disease-associated PrP isoforms accumulate in cells after proteasome inhibition leading to increased cell death, and abnormal beta-sheet-rich PrP isoforms have been shown to inhibit the catalytic activity of the proteasome. Here we review potential interactions between prions and the proteasome outlining how the UPS may be implicated in prion-mediated neurodegeneration.
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Affiliation(s)
- Pelagia Deriziotis
- Department of Neurodegenerative Disease, Institute of Neurology, University College London, London, WC1N 3BG, UK
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19
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Gu Y, Singh A, Bose S, Singh N. Pathogenic mutations in the glycosylphosphatidylinositol signal peptide of PrP modulate its topology in neuroblastoma cells. Mol Cell Neurosci 2008; 37:647-56. [PMID: 18325785 DOI: 10.1016/j.mcn.2007.08.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 07/27/2007] [Accepted: 08/06/2007] [Indexed: 10/22/2022] Open
Abstract
Point mutations M232R (PrP(232R)), M232T (PrP(232T)), and P238S (PrP(238S)) in the glycosylphosphatidylinositol signal peptide (GPI-SP) of the prion protein (PrP(C)) segregate with familial Creutzfeldt-Jakob disease (CJD). However, the mechanism by which these mutations induce cytotoxicity is unclear since the GPI-SP is replaced by a GPI anchor within 5 min of PrP synthesis and translocation into the endoplasmic reticulum (ER). To examine if mutations in this region interfere with translocation of nascent PrP into the ER or anchor addition, the metabolism of PrP(232R) and PrP(232T) was investigated in transfected human neuroblastoma cells. In this report, we demonstrate that PrP mutations M232R and M232T do not interfere with GPI anchor addition. Instead, these mutations increase the stability and transport of GPI-SP mediated post-translationally translocated PrP to the plasma membrane, where it is linked to the lipid bilayer in a potentially neurotoxic C-transmembrane ((Ctm)PrP) orientation. Furthermore, we demonstrate that the GPI-SP of PrP functions as an efficient co-translational and inefficient post-translational ER translocation signal when tagged to an unrelated protein, underscoring the functional versatility of this peptide. These data uncover an alternate pathway of ER translocation for nascent PrP, and provide information on the possible mechanism(s) of neurotoxicity by mutations in the GPI-SP.
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Affiliation(s)
- Yaping Gu
- Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, Ohio 44106, USA
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20
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Krammer C, Suhre MH, Kremmer E, Diemer C, Hess S, Schätzl HM, Scheibel T, Vorberg I. Prion protein/protein interactions: fusion with yeast Sup35p-NM modulates cytosolic PrP aggregation in mammalian cells. FASEB J 2007; 22:762-73. [PMID: 17928365 DOI: 10.1096/fj.07-8733com] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In mammalian prion diseases, an abnormally folded, aggregated form of the prion protein (PrP(Sc)) appears to catalyze a conformational switch of its cellular isoform (PrP(C)) to an aggregated state. A similar prion-like phenomenon has been reported for the Saccharomyces cerevisiae translation termination factor Sup35p that can adopt a self-propagating conformation. We have compared aggregation propensities of chimeric proteins derived from the Sup35p prion domain NM and PrP in vitro and in the cytosol of mammalian cells. Sup35p-NM and PrP displayed strikingly different aggregation behaviors when expressed in mammalian cells, with NM remaining soluble and cytosolic PrP spontaneously aggregating due to the globular domain of PrP. When fused to PrP(90-230), Sup35p-M exhibited an inhibitory effect for nucleation but increased aggregate growth, potentially by facilitating recruitment of newly synthesized chimeric proteins into the growing aggregates. This effect, however, could, to some extent, be counteracted by the prion-forming region Sup35p-N, thereby increasing aggregate frequency. Interestingly, a lowered nucleation rate was also observed in the presence of the amino-terminal region of PrP, suggesting that Sup35p-M and PrP(23-90) share some biological function in prion protein assembly. Our results provide new insights into prion protein aggregation behaviors, demonstrating the impact of dynamic interactions between prion domains and suggesting that aggregation of yeast and mammalian prion proteins is strongly influenced by yet unidentified cellular conditions or factors.
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Affiliation(s)
- Carmen Krammer
- Institute of Virology, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany
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21
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Abstract
The biochemical nature and the replication of infectious prions have been intensively studied in recent years. Much less is known about the cellular events underlying neuronal dysfunction and cell death. As the cellular function of the normal cellular isoform of prion protein is not exactly known, the impact of gain of toxic function or loss of function, or a combination of both, in prion pathology is still controversial. There is increasing evidence that the normal cellular isoform of the prion protein is a key mediator in prion pathology. Transgenic models were instrumental in dissecting propagation of prions, disease-associated isoforms of prion protein and amyloid production, and induction of neurodegeneration. Four experimental avenues will be discussed here which address scenarios of inappropriate trafficking, folding, or targeting of the prion protein.
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Affiliation(s)
- Jörg Tatzelt
- Department of Biochemistry, Neurobiochemistry, Ludwig-Maximilians-University Munich, Germany.
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22
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Abstract
Neuronal vacuolation (spongiosis), neuronal death, and pronounced glial reactions are the hallmarks of transmissible spongiform encephalopathies (TSEs), or prion diseases. A wealth of physical, biochemical, and immunological evidence indicates that the TSE agent, termed prion, does not contain agent-specific nucleic acid encoding its own constituents, as is the case for all other infectious pathogens. Also, no adaptive immune responses are elicited upon infection. A defining feature of TSEs is the deposition, mainly in the brain and lymphoreticular tissues, of an aggregated and structurally abnormal protein, designated PrP(Sc) or PrP-res, which represents a conformational isomer of the ubiquitous surface protein PrP(C). Biochemical and genetic evidence link PrP and its gene to the disease. Although TSEs are by definition transmissible, a growing number of Prnp-associated non-infectious neurodegenerative proteinopathies are now being recognized.
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Affiliation(s)
- Adriano Aguzzi
- Institute of Neuropathology, Universitätsspital Zürich, Zürich, Switzerland.
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23
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Rambold AS, Miesbauer M, Rapaport D, Bartke T, Baier M, Winklhofer KF, Tatzelt J. Association of Bcl-2 with misfolded prion protein is linked to the toxic potential of cytosolic PrP. Mol Biol Cell 2006; 17:3356-68. [PMID: 16707568 PMCID: PMC1525242 DOI: 10.1091/mbc.e06-01-0083] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Revised: 04/17/2006] [Accepted: 05/10/2006] [Indexed: 01/07/2023] Open
Abstract
Protein misfolding is linked to different neurodegenerative disorders like Alzheimer's disease, polyglutamine, and prion diseases. We investigated the cytotoxic effects of aberrant conformers of the prion protein (PrP) and show that toxicity is specifically linked to misfolding of PrP in the cytosolic compartment and involves binding of PrP to the anti-apoptotic protein Bcl-2. PrP targeted to different cellular compartments, including the cytosol, nucleus, and mitochondria, adopted a misfolded and partially proteinase K-resistant conformation. However, only in the cytosol did the accumulation of misfolded PrP induce apoptosis. Apoptotic cell death was also induced by two pathogenic mutants of PrP, which are partially localized in the cytosol. A mechanistic analysis revealed that the toxic potential is linked to an internal domain of PrP (amino acids 115-156) and involves coaggregation of cytosolic PrP with Bcl-2. Increased expression of the chaperones Hsp70 and Hsp40 prevented the formation of PrP/Bcl-2 coaggregates and interfered with PrP-induced apoptosis. Our study reveals a compartment-specific toxicity of PrP misfolding that involves coaggregation of Bcl-2 and indicates a protective role of molecular chaperones.
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Affiliation(s)
- Angelika S. Rambold
- *Department of Biochemistry, Neurobiochemistry, Ludwig-Maximilians-Universität München, D-80336 München, Germany
| | - Margit Miesbauer
- *Department of Biochemistry, Neurobiochemistry, Ludwig-Maximilians-Universität München, D-80336 München, Germany
| | - Doron Rapaport
- Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Till Bartke
- Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom; and
| | | | - Konstanze F. Winklhofer
- *Department of Biochemistry, Neurobiochemistry, Ludwig-Maximilians-Universität München, D-80336 München, Germany
| | - Jörg Tatzelt
- *Department of Biochemistry, Neurobiochemistry, Ludwig-Maximilians-Universität München, D-80336 München, Germany
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24
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Apodaca J, Kim I, Rao H. Cellular tolerance of prion protein PrP in yeast involves proteolysis and the unfolded protein response. Biochem Biophys Res Commun 2006; 347:319-26. [PMID: 16808901 DOI: 10.1016/j.bbrc.2006.06.078] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Accepted: 06/15/2006] [Indexed: 11/28/2022]
Abstract
Secretory proteins undergo a stringent quality control process in the endoplasmic reticulum (ER). Misfolded ER proteins are returned to the cytosol and destroyed by the proteasome. Prion protein PrP is degraded by the proteasome in mammalian cells. However, the significance of proteolysis on PrP-induced cell death is controversial. Moreover, the specific pathway involved in PrP degradation remains unknown. Here, we demonstrate that the unglycosylated form of human PrP is subjected to the ER-associated protein degradation (ERAD) process in the yeast Saccharomyces cerevisiae. We also show that unglycosylated PrP is degraded by the Hrd1-Hrd3 pathway. Accumulation of misfolded proteins triggers the unfolded protein response (UPR), which promotes substrate refolding. Interestingly, we find that the expression of PrP leads to growth impairment in cells deficient in UPR and ERAD. These findings raise the possibility that decreased UPR activity and proteolysis may contribute to the pathogenesis of some prion-related diseases.
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Affiliation(s)
- Jennifer Apodaca
- Institute of Biotechnology, Department of Molecular Medicine, The University of Texas Health Science Center, San Antonio, 78245, USA
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25
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Gu Y, Luo X, Basu S, Fujioka H, Singh N. Cell-specific metabolism and pathogenesis of transmembrane prion protein. Mol Cell Biol 2006; 26:2697-715. [PMID: 16537913 PMCID: PMC1430324 DOI: 10.1128/mcb.26.7.2697-2715.2006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The C-transmembrane form of prion protein ((Ctm)PrP) has been implicated in prion disease pathogenesis, but the factors underlying its biogenesis and cyotoxic potential remain unclear. Here we show that (Ctm)PrP interferes with cytokinesis in cell lines where it is transported to the plasma membrane. These cells fail to separate following cell division, assume a variety of shapes and sizes, and contain multiple nuclei, some of which are pyknotic. Furthermore, the synthesis and transport of (Ctm)PrP to the plasma membrane are modulated through a complex interaction between cis- and trans-acting factors and the endoplasmic reticulum translocation machinery. Thus, insertion of eight amino acids before or within the N region of the N signal peptide (N-SP) of PrP results in the exclusive synthesis of (Ctm)PrP regardless of the charge conferred to the N region. Subsequent processing and transport of (Ctm)PrP are modulated by specific amino acids in the N region of the N-SP and by the cell line of expression. Although the trigger for (Ctm)PrP upregulation in naturally occurring prion disorders remains elusive, these data highlight the underlying mechanisms of (Ctm)PrP biogenesis and neurotoxicity and reinforce the idea that (Ctm)PrP may serve as the proximate cause of neuronal death in certain prion disorders.
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Affiliation(s)
- Yaping Gu
- Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, Ohio 44106, USA
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26
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Wang X, Wang F, Arterburn L, Wollmann R, Ma J. The interaction between cytoplasmic prion protein and the hydrophobic lipid core of membrane correlates with neurotoxicity. J Biol Chem 2006; 281:13559-13565. [PMID: 16537534 DOI: 10.1074/jbc.m512306200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prion protein (PrP), normally a cell surface protein, has been detected in the cytosol of a subset of neurons. The appearance of PrP in the cytosol could result from either retro-translocation of misfolded PrP from the endoplasmic reticulum (ER) or impaired import of PrP into the ER. Transgenic mice expressing cytoplasmic PrP (cyPrP) developed neurodegeneration in cerebellar granular neurons, although no detectable pathology was observed in other brain regions. In order to understand why granular neurons in the cerebellum were most susceptible to cyPrP-induced degeneration, we investigated the subcellular localization of cyPrP. Interestingly, we found that cyPrP is membrane-bound. In transfected cells, it binds to the ER and plasma/endocytic vesicular membranes. In transgenic mice, it is associated with synaptic and microsomal membranes. Furthermore, the cerebellar neurodegeneration in transgenic mice correlates with the interaction between cyPrP and the hydrophobic lipid core of the membrane but not with either the aggregation status or the dosage of cyPrP. These results suggest that lipid membrane perturbation could be a cellular mechanism for cyPrP-induced neurotoxicity and explain the seemingly conflicting results concerning cyPrP.
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Affiliation(s)
- Xinhe Wang
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210
| | - Fei Wang
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210
| | - Linnea Arterburn
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210
| | - Robert Wollmann
- Department of Pathology, University of Chicago, Chicago, Illinois 60637
| | - Jiyan Ma
- Department of Molecular and Cellular Biochemistry, Ohio State University, Columbus, Ohio 43210.
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27
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Abstract
The etiologies of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, polyglutamine diseases, or prion diseases may be diverse; however, aberrations in protein folding, processing, and/or degradation are common features of these entities, implying a role of quality control systems, such as molecular chaperones and the ubiquitin-proteasome pathway. There is substantial evidence for a causal role of protein misfolding in the pathogenic process coming from neuropathology, genetics, animal modeling, and biophysics. The presence of protein aggregates in all neurodegenerative diseases gave rise to the hypothesis that protein aggregates, be it intracellular or extracellular deposits, may perturb the cellular homeostasis and disintegrate neuronal function (Table 1). More recently, however, an increasing number of studies have indicated that protein aggregates are not toxic per se and might even serve a protective role by sequestering misfolded proteins. Specifically, experimental models of polyglutamine diseases, Alzheimer's disease, and Parkinson's disease revealed that the appearance of aggregates can be dissociated from neuronal toxicity, while misfolded monomers or oligomeric intermediates seem to be the toxic species. The unique features of molecular chaperones to assist in the folding of nascent proteins and to prevent stress-induced misfolding was the rationale to exploit their effects in different models of neurodegenerative diseases. This chapter concentrates on two neurodegenerative diseases, Parkinson's disease and prion diseases, with a special focus on protein misfolding and a possible role of molecular chaperones.
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Affiliation(s)
- K F Winklhofer
- Department of Cellular Biochemistry, Max-Planck-Institute for Biochemistry, Martinsried, Germany.
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28
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Mohan J, Hopkins J, Mabbott NA. Skin-derived dendritic cells acquire and degrade the scrapie agent following in vitro exposure. Immunology 2005; 116:122-33. [PMID: 16108824 PMCID: PMC1802412 DOI: 10.1111/j.1365-2567.2005.02207.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The accumulation of the scrapie agent in lymphoid tissues following inoculation via the skin is critical for efficient neuroinvasion, but how the agent is initially transported from the skin to the draining lymph node is not known. Langerhans cells (LCs) are specialized antigen-presenting cells that continually sample their microenvironment within the epidermis and transport captured antigens to draining lymph nodes. We considered LCs probable candidates to acquire and transport the scrapie agent after inoculation via the skin. XS106 cells are dendritic cells (DCs) isolated from mouse epidermis with characteristics of mature LC cells. To investigate the potential interaction of LCs with the scrapie agent XS106 cells were exposed to the scrapie agent in vitro. We show that XS106 cells rapidly acquire the scrapie agent following in vitro exposure. In addition, XS106 cells partially degrade the scrapie agent following extended cultivation. These data suggest that LCs might acquire and degrade the scrapie agent after inoculation via the skin, but data from additional experiments demonstrate that this ability could be lost in the presence of lipopolysaccharide or other immunostimulatory molecules. Our studies also imply that LCs would not undergo maturation following uptake of the scrapie agent in the skin, as the expression of surface antigens associated with LC maturation were unaltered following exposure. In conclusion, although LCs or DCs have the potential to acquire the scrapie agent within the epidermis our data suggest it is unlikely that they become activated and stimulated to transport the agent to the draining lymph node.
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29
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Abstract
Devising approaches to the therapy of transmissible spongiform encephalopathies, or prion diseases, is beset by many difficulties. For one, the nature of the infectious agent, the prion, is understood only in outline, and its composition, structure, and mode of replication are still shrouded in mystery. In addition, the mechanism of pathogenesis is not well understood. Because clinical disease affects mainly the brain parenchyme, therapeutic agents must be able to traverse the brain-blood barrier (BBB) or have to be introduced directly into the cerebrospinal fluid or brain tissue. And finally, because the disease is usually recognized only after onset of severe clinical symptoms, the question arises as to whether the neurodegenerative processes can be reversed to any extent after a successful eradication of the agent.
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Affiliation(s)
- Charles Weissmann
- Department of Neurodegenerative Disease/MRC Prion Unit, Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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30
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Henn IH, Gostner JM, Lackner P, Tatzelt J, Winklhofer KF. Pathogenic mutations inactivate parkin by distinct mechanisms. J Neurochem 2005; 92:114-22. [PMID: 15606901 DOI: 10.1111/j.1471-4159.2004.02854.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Loss of parkin function is the major cause of autosomal recessive Parkinson's disease (ARPD). A wide variety of parkin mutations have been identified in patients; however, the pathophysiological mechanisms leading to the inactivation of mutant parkin are poorly understood. In this study we characterized pathogenic C- and N-terminal parkin mutants and found distinct pathways of parkin inactivation. Deletion of the C terminus abrogated the association of parkin with cellular membranes and induced rapid misfolding and aggregation. Four N-terminal missense mutations, located within the ubiquitin-like domain (UBL), decrease the stability of parkin; as a consequence, these mutants are rapidly degraded by the proteasome. Furthermore, we present evidence that a smaller parkin species of 42 kDa, which is present in extracts prepared from human brain and cultured cells, originates from an internal start site and lacks the N-terminal UBL domain.
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Affiliation(s)
- Iris H Henn
- Department of Cellular Biochemistry, Max Planck Institute for Biochemistry, Martinsried, Germany
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31
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Kiachopoulos S, Bracher A, Winklhofer KF, Tatzelt J. Pathogenic mutations located in the hydrophobic core of the prion protein interfere with folding and attachment of the glycosylphosphatidylinositol anchor. J Biol Chem 2004; 280:9320-9. [PMID: 15591591 DOI: 10.1074/jbc.m412525200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Abnormal folding of the cellular prion protein (PrPC) is a key feature in prion diseases. Here we show that two pathogenic mutations linked to inherited prion diseases in humans severely affect folding and maturation of PrPC in the secretory pathway of neuronal cells. PrP-T183A and PrP-F198S adopt a misfolded and partially protease-resistant conformation, lack the glycosylphosphatidylinositol anchor, and are not complex glycosylated. These misfolded PrP mutants are not retained in the endoplasmic reticulum and are not subjected to the endoplasmic reticulum-associated degradation pathway. They rather are secreted, moreover, these mutants can be internalized by heterologous cells. Structural studies indicated that the side chains of Thr183 and Phe198 contribute to interactions between secondary structure elements in the C-terminal globular domain of PrPC. Consequently, we reasoned that a destabilized tertiary structure of these mutants could account for the defect in maturation. Indeed, mutations predicted to interfere selectively with the packing of the hydrophobic core of PrPC prevented the addition of the glycosylphosphatidylinositol anchor. Our study reveals that formation of the C-terminal globular domain of PrPC has an impact on membrane anchoring and indicates that misfolded secreted forms of the prion protein are linked to inherited prion diseases in humans.
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Affiliation(s)
- Sophia Kiachopoulos
- Department of Cellular Biochemistry, Max-Planck-Institute for Biochemie, D-82152 Martinsried, Germany
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Abstract
There is little doubt that the main component of the transmissible agent of spongiform encephalopathies - the prion - is a conformational variant of the ubiquitous host protein PrP(C), and that the differing properties of various prion strains are associated with different abnormal conformations of this protein. The precise structure of the prion is not yet known, nor are the mechanisms of infection, conformational conversion and pathogenesis understood.
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Affiliation(s)
- Charles Weissmann
- MRC Prion Unit, Department of Neurodegenerative Disease, Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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Roucou X, LeBlanc AC. Cellular prion protein neuroprotective function: implications in prion diseases. J Mol Med (Berl) 2004; 83:3-11. [PMID: 15645198 DOI: 10.1007/s00109-004-0605-5] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Accepted: 09/10/2004] [Indexed: 10/26/2022]
Abstract
Prion protein can display two conformations: a normal cellular conformation (PrP) and a pathological conformation associated with prion diseases (PrP(Sc)). Three complementary strategies are used by researchers investigating how PrP is involved in the pathogenesis of prion diseases: elucidation of the normal function of PrP, determination of how PrP(Sc) is toxic to neurons, and unraveling the mechanism for the conversion of PrP to PrP(Sc). We review the normal function of PrP as an antioxidant and an antiapoptotic protein in vivo and in vitro. This review also addresses contrasting evidence that PrP is cytotoxic. Finally, we discuss the implication of the neuroprotective role of PrP in prion diseases.
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Affiliation(s)
- Xavier Roucou
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, 3755 Ch. Cote Ste-Catherine, Montreal, QC, H3T 1E2, Canada
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Li A, Dong J, Harris DA. Cell Surface Expression of the Prion Protein in Yeast Does Not Alter Copper Utilization Phenotypes. J Biol Chem 2004; 279:29469-77. [PMID: 15090539 DOI: 10.1074/jbc.m402517200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Prion diseases are fatal neurodegenerative disorders that result from conversion of a normal, cell surface glycoprotein (PrP(C)) into a conformationally altered isoform (PrP(Sc)) that is thought to be infectious. Although a great deal is known about the role of PrP(Sc) in the disease process, the physiological function of PrP(C) has remained enigmatic. In this report, we have used the yeast Saccharomyces cerevisiae to test one hypothesized function of PrP(C), as a receptor for the uptake or efflux of copper ions. We first modified the PrP signal peptide by replacing its hydrophobic core with the signal sequence from the yeast protein dipeptidyl aminopeptidase B, so that the resulting protein was targeted cotranslationally to the secretory pathway when synthesized in yeast. PrP molecules with the modified signal peptide were efficiently glycosylated, glycolipid-anchored, and localized to the plasma membrane. We then tested whether PrP expression altered the growth deficiency phenotypes of yeast strains harboring deletions in genes that encode key components of copper utilization pathways, including transporters, chaperones, pumps, reductases, and cuproenzymes. We found that PrP did not rescue any of these mutant phenotypes, arguing against a direct role for the protein in copper utilization. Our results provide further clarification of the physiological function of PrP(C), and lay the groundwork for using PrP-expressing yeast to study other aspects of prion biology.
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Affiliation(s)
- Aimin Li
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri 63110, USA
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Kiachopoulos S, Heske J, Tatzelt J, Winklhofer KF. Misfolding of the Prion Protein at the Plasma Membrane Induces Endocytosis, Intracellular Retention and Degradation. Traffic 2004; 5:426-36. [PMID: 15117317 DOI: 10.1111/j.1398-9219.2004.00185.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Suramin induces misfolding of the cellular prion protein (PrP(C)) and interferes with the propagation of infectious scrapie prions. A mechanistic analysis of this effect revealed that suramin-induced misfolding occurs at the plasma membrane and is dependent on the proximal region of the C-terminal domain (aa 90-158) of PrP(C). The conformational transition induces rapid internalization, mediated by the unstructured N-terminal domain, and subsequent intracellular degradation of PrP(C). As a consequence, PrP Delta N adopts a misfolded conformation at the plasma membrane; however, internalization is significantly delayed. We also found that misfolding and intracellular retention of PrP(C) can be induced by copper and that, moreover, copper interferes with the propagation of the pathogenic prion protein (PrP(Sc)) in scrapie-infected N2a cells. Our study revealed a quality control pathway for aberrant PrP conformers present at the plasma membrane and identified distinct PrP domains involved.
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Affiliation(s)
- Sophia Kiachopoulos
- Department of Cellular Biochemistry, Max-Planck-Institut für Biochemie, Am Klopferspitz 18, D-82152 Martinsried, Germany
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Heske J, Heller U, Winklhofer KF, Tatzelt J. The C-terminal globular domain of the prion protein is necessary and sufficient for import into the endoplasmic reticulum. J Biol Chem 2003; 279:5435-43. [PMID: 14645231 DOI: 10.1074/jbc.m309570200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian prion protein (PrP) is composed of an unstructured flexible N-terminal region and a C-terminal globular domain. We examined the import of PrP into the endoplasmic reticulum (ER) of neuronal cells and show that information present in the C-terminal globular domain is required for ER import of the N terminus. N-terminal fragments of PrP, devoid of structural domains located in the C terminus, remained in the cytosol with an uncleaved signal peptide and were rapidly degraded by the proteasome. Conversely, the separate C-terminal domain of PrP, comprising the highly ordered helix 2-loop-helix 3 motif, was entirely imported into the ER. As a consequence, two PrP mutants linked to inherited prion disease in humans, PrP-W145Stop and PrP-Q160Stop, were partially retained in the cytosol. The cytosolic fraction was characterized by an uncleaved N-terminal signal peptide and was degraded by the proteasome. Our study identified a new regulatory element in the C-terminal globular domain of PrP necessary and sufficient to promote import of PrP into the ER.
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Affiliation(s)
- Johanna Heske
- Department of Cellular Biochemistry, Max-Planck-Institut für Biochemie, Am Klopferspitz 18, D-82152 Martinsried, Germany
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