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The 37/67 kDa laminin receptor (LR) inhibitor, NSC47924, affects 37/67 kDa LR cell surface localization and interaction with the cellular prion protein. Sci Rep 2016; 6:24457. [PMID: 27071549 PMCID: PMC4829897 DOI: 10.1038/srep24457] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 03/22/2016] [Indexed: 12/17/2022] Open
Abstract
The 37/67 kDa laminin receptor (LR) is a non-integrin protein, which binds both laminin-1 of the extracellular matrix and prion proteins, that hold a central role in prion diseases. The 37/67 kDa LR has been identified as interactor for the prion protein (PrP(C)) and to be required for pathological PrP (PrP(Sc)) propagation in scrapie-infected neuronal cells, leading to the possibility that 37/67 kDa LR-PrP(C) interaction is related to the pathogenesis of prion diseases. A relationship between 37/67 kDa LR and PrP(C) in the presence of specific LR inhibitor compounds has not been investigated yet. We have characterized the trafficking of 37/67 kDa LR in both neuronal and non-neuronal cells, finding the receptor on the cell surface and nuclei, and identified the 67 kDa LR as the almost exclusive isoform interacting with PrP(C). Here, we show that the treatment with the 37/67 kDa LR inhibitor, NSC47924, affects both the direct 37/67 kDa LR-PrP(C) interaction in vitro and the formation of the immunocomplex in live cells, inducing a progressive internalization of 37/67 kDa LR and stabilization of PrP(C) on the cell surface. These data reveal NSC47924 as a useful tool to regulate PrP(C) and 37/67 kDa LR trafficking and degradation, representing a novel small molecule to be tested against prion diseases.
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Carneiro MV, Americo TA, Guimarães MZ, Linden R. The prion protein selectively binds to and modulates the content of purinergic receptor P2X4R. Biochem Biophys Res Commun 2016; 472:293-8. [DOI: 10.1016/j.bbrc.2016.02.122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 02/29/2016] [Indexed: 10/24/2022]
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da Luz MHM, Glezer I, Xavier AM, da Silva MAP, Pino JMV, Zamith TP, Vieira TF, Antonio BB, Antunes HKM, Martins VR, Lee KS. Expression of Tyrosine Hydroxylase is Negatively Regulated Via Prion Protein. Neurochem Res 2016; 41:1691-9. [DOI: 10.1007/s11064-016-1885-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/26/2016] [Accepted: 03/08/2016] [Indexed: 12/31/2022]
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Do prion protein gene polymorphisms induce apoptosis in non-mammals? J Biosci 2016; 41:97-107. [PMID: 26949092 DOI: 10.1007/s12038-015-9584-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Genetic variations such as single nucleotide polymorphisms (SNPs) in prion protein coding gene, Prnp, greatly affect susceptibility to prion diseases in mammals. Here, the coding region of Prnp was screened for polymorphisms in redeared turtle, Trachemys scripta. Four polymorphisms, L203V, N205I, V225A and M237V, were common in 15 out of 30 turtles; in one sample, three SNPs, L203V, N205I and M237V, and in the remaining 14 samples, only L203V and N205I polymorphisms, were investigated. Besides, C658T, C664T, C670A and C823A SNPs were silent mutations. To elucidate the relationship between the SNPs and apoptosis, TUNEL assays and active caspase-3 immunodetection techniques in brain sections of the polymorphic samples were performed. The results revealed that TUNEL-positive cells and active caspase-3-positive cells in the turtles with four polymorphisms were significantly increased compared with those of the turtles with two polymorphisms (P less than 0.01 and P less than 0.05, respectively). In conclusion, this study provides preliminary information about the possible relationship between SNPs within the Prnp locus and apoptosis in a non-mammalian species, Trachemys scripta, in which prion disease has never been reported.
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Milisav I, Šuput D, Ribarič S. Unfolded Protein Response and Macroautophagy in Alzheimer's, Parkinson's and Prion Diseases. Molecules 2015; 20:22718-56. [PMID: 26694349 PMCID: PMC6332363 DOI: 10.3390/molecules201219865] [Citation(s) in RCA: 27] [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: 10/30/2015] [Revised: 11/30/2015] [Accepted: 12/09/2015] [Indexed: 12/13/2022] Open
Abstract
Proteostasis are integrated biological pathways within cells that control synthesis, folding, trafficking and degradation of proteins. The absence of cell division makes brain proteostasis susceptible to age-related changes and neurodegeneration. Two key processes involved in sustaining normal brain proteostasis are the unfolded protein response and autophagy. Alzheimer’s disease (AD), Parkinson’s disease (PD) and prion diseases (PrDs) have different clinical manifestations of neurodegeneration, however, all share an accumulation of misfolded pathological proteins associated with perturbations in unfolded protein response and macroautophagy. While both the unfolded protein response and macroautophagy play an important role in the prevention and attenuation of AD and PD progression, only macroautophagy seems to play an important role in the development of PrDs. Macroautophagy and unfolded protein response can be modulated by pharmacological interventions. However, further research is necessary to better understand the regulatory pathways of both processes in health and neurodegeneration to be able to develop new therapeutic interventions.
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Affiliation(s)
- Irina Milisav
- Institute of Pathophysiology, Faculty of Medicine, Zaloška 4, Ljubljana SI-1000, Slovenia.
- Faculty of Health Sciences, Zdravstvena pot 5, SI-1000 Ljubljana, Slovenija.
| | - Dušan Šuput
- Institute of Pathophysiology, Faculty of Medicine, Zaloška 4, Ljubljana SI-1000, Slovenia.
| | - Samo Ribarič
- Institute of Pathophysiology, Faculty of Medicine, Zaloška 4, Ljubljana SI-1000, Slovenia.
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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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Katorcha E, Klimova N, Makarava N, Savtchenko R, Pan X, Annunziata I, Takahashi K, Miyagi T, Pshezhetsky AV, d’Azzo A, Baskakov IV. Loss of Cellular Sialidases Does Not Affect the Sialylation Status of the Prion Protein but Increases the Amounts of Its Proteolytic Fragment C1. PLoS One 2015; 10:e0143218. [PMID: 26569607 PMCID: PMC4646690 DOI: 10.1371/journal.pone.0143218] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 11/02/2015] [Indexed: 11/29/2022] Open
Abstract
The central molecular event underlying prion diseases involves conformational change of the cellular form of the prion protein (PrPC), which is a sialoglycoprotein, into the disease-associated, transmissible form denoted PrPSc. Recent studies revealed a correlation between the sialylation status of PrPSc and incubation time to disease and introduced a new hypothesis that progression of prion diseases could be controlled or reversed by altering the sialylation level of PrPC. Of the four known mammalian sialidases, the enzymes that cleave off sialic acid residues, only NEU1, NEU3 and NEU4 are expressed in the brain. To test whether cellular sialidases control the steady-state sialylation level of PrPC and to identify the putative sialidase responsible for desialylating PrPC, we analyzed brain-derived PrPC from knockout mice deficient in Neu1, Neu3, Neu4, or from Neu3/Neu4 double knockouts. Surprisingly, no differences in the sialylation of PrPC or its proteolytic product C1 were noticed in any of the knockout mice tested as compared to the age-matched controls. However, significantly higher amounts of the C1 fragment relative to full-length PrPC were detected in the brains of Neu1 knockout mice as compared to WT mice or to the other knockout mice. Additional experiments revealed that in neuroblastoma cell line the sialylation pattern of C1 could be changed by an inhibitor of sialylatransferases. In summary, this study suggests that targeting cellular sialidases is apparently not the correct strategy for altering the sialylation levels of PrPC, whereas modulating the activity of sialylatransferases might offer a more promising approach. Our findings also suggest that catabolism of PrPC involves its α-cleavage followed by desialylation of the resulting C1 fragments by NEU1 and consequent fast degradation of the desialylated products.
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Affiliation(s)
- Elizaveta Katorcha
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Nina Klimova
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Natallia Makarava
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Regina Savtchenko
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Xuefang Pan
- Division of Medical Genetics, Sainte-Justine University Hospital Research Center, University of Montreal, Montreal, QC, Canada
| | - Ida Annunziata
- Department of Genetics, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Kohta Takahashi
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai, Miyagi, Japan
| | - Taeko Miyagi
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai, Miyagi, Japan
| | - Alexey V. Pshezhetsky
- Division of Medical Genetics, Sainte-Justine University Hospital Research Center, University of Montreal, Montreal, QC, Canada
| | - Alessandra d’Azzo
- Department of Genetics, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Ilia V. Baskakov
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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Bate C, Nolan W, Williams A. Sialic Acid on the Glycosylphosphatidylinositol Anchor Regulates PrP-mediated Cell Signaling and Prion Formation. J Biol Chem 2015; 291:160-70. [PMID: 26553874 DOI: 10.1074/jbc.m115.672394] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Indexed: 01/24/2023] Open
Abstract
The prion diseases occur following the conversion of the cellular prion protein (PrP(C)) into disease-related isoforms (PrP(Sc)). In this study, the role of the glycosylphosphatidylinositol (GPI) anchor attached to PrP(C) in prion formation was examined using a cell painting technique. PrP(Sc) formation in two prion-infected neuronal cell lines (ScGT1 and ScN2a cells) and in scrapie-infected primary cortical neurons was increased following the introduction of PrP(C). In contrast, PrP(C) containing a GPI anchor from which the sialic acid had been removed (desialylated PrP(C)) was not converted to PrP(Sc). Furthermore, the presence of desialylated PrP(C) inhibited the production of PrP(Sc) within prion-infected cortical neurons and ScGT1 and ScN2a cells. The membrane rafts surrounding desialylated PrP(C) contained greater amounts of sialylated gangliosides and cholesterol than membrane rafts surrounding PrP(C). Desialylated PrP(C) was less sensitive to cholesterol depletion than PrP(C) and was not released from cells by treatment with glimepiride. The presence of desialylated PrP(C) in neurons caused the dissociation of cytoplasmic phospholipase A2 from PrP-containing membrane rafts and reduced the activation of cytoplasmic phospholipase A2. These findings show that the sialic acid moiety of the GPI attached to PrP(C) modifies local membrane microenvironments that are important in PrP-mediated cell signaling and PrP(Sc) formation. These results suggest that pharmacological modification of GPI glycosylation might constitute a novel therapeutic approach to prion diseases.
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Affiliation(s)
- Clive Bate
- From the Department of Pathology and Pathogen Biology, Royal Veterinary College, North Mymms, Hertfordshire AL9 7TA, United Kingdom and
| | - William Nolan
- From the Department of Pathology and Pathogen Biology, Royal Veterinary College, North Mymms, Hertfordshire AL9 7TA, United Kingdom and
| | - Alun Williams
- the Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 OES, United Kingdom
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59
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Trafficking and degradation pathways in pathogenic conversion of prions and prion-like proteins in neurodegenerative diseases. Virus Res 2015; 207:146-54. [DOI: 10.1016/j.virusres.2015.01.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 10/01/2014] [Accepted: 01/22/2015] [Indexed: 11/20/2022]
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Abstract
UNLABELLED Mammalian prions are unconventional infectious agents composed primarily of the misfolded aggregated host prion protein PrP, termed PrP(Sc). Prions propagate by the recruitment and conformational conversion of cellular prion protein into abnormal prion aggregates on the cell surface or along the endocytic pathway. Cellular glycosaminoglycans have been implicated as the first attachment sites for prions and cofactors for cellular prion replication. Glycosaminoglycan mimetics and obstruction of glycosaminoglycan sulfation affect prion replication, but the inhibitory effects on different strains and different stages of the cell infection have not been thoroughly addressed. We examined the effects of a glycosaminoglycan mimetic and undersulfation on cellular prion protein metabolism, prion uptake, and the establishment of productive infections in L929 cells by two mouse-adapted prion strains. Surprisingly, both treatments reduced endogenous sulfated glycosaminoglycans but had divergent effects on cellular PrP levels. Chemical or genetic manipulation of glycosaminoglycans did not prevent PrP(Sc) uptake, arguing against their roles as essential prion attachment sites. However, both treatments effectively antagonized de novo prion infection independently of the prion strain and reduced PrP(Sc) formation in chronically infected cells. Our results demonstrate that sulfated glycosaminoglycans are dispensable for prion internalization but play a pivotal role in persistently maintained PrP(Sc) formation independent of the prion strain. IMPORTANCE Recently, glycosaminoglycans (GAGs) became the focus of neurodegenerative disease research as general attachment sites for cell invasion by pathogenic protein aggregates. GAGs influence amyloid formation in vitro. GAGs are also found in intra- and extracellular amyloid deposits. In light of the essential role GAGs play in proteinopathies, understanding the effects of GAGs on protein aggregation and aggregate dissemination is crucial for therapeutic intervention. Here, we show that GAGs are dispensable for prion uptake but play essential roles in downstream infection processes. GAG mimetics also affect cellular GAG levels and localization and thus might affect prion propagation by depleting intracellular cofactor pools.
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61
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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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62
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Didonna A, Venturini AC, Hartman K, Vranac T, Čurin Šerbec V, Legname G. Characterization of four new monoclonal antibodies against the distal N-terminal region of PrP(c). PeerJ 2015; 3:e811. [PMID: 25802800 PMCID: PMC4369333 DOI: 10.7717/peerj.811] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Accepted: 02/11/2015] [Indexed: 12/15/2022] Open
Abstract
Prion diseases are a group of fatal neurodegenerative disorders that affect humans and animals. They are characterized by the accumulation in the central nervous system of a pathological form of the host-encoded prion protein (PrPC). The prion protein is a membrane glycoprotein that consists of two domains: a globular, structured C-terminus and an unstructured N-terminus. The N-terminal part of the protein is involved in different functions in both health and disease. In the present work we discuss the production and biochemical characterization of a panel of four monoclonal antibodies (mAbs) against the distal N-terminus of PrPC using a well-established methodology based on the immunization of Prnp0/0 mice. Additionally, we show their ability to block prion (PrPSc) replication at nanomolar concentrations in a cell culture model of prion infection. These mAbs represent a promising tool for prion diagnostics and for studying the physiological role of the N-terminal domain of PrPC.
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Affiliation(s)
- Alessandro Didonna
- Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Anja Colja Venturini
- Department for Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
| | - Katrina Hartman
- Department for Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
| | - Tanja Vranac
- Department for Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
| | - Vladka Čurin Šerbec
- Department for Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
| | - Giuseppe Legname
- Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy.,ELETTRA-Sincrotrone Trieste S.C.p.A, Trieste, Italy
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63
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Lau A, McDonald A, Daude N, Mays CE, Walter ED, Aglietti R, Mercer RCC, Wohlgemuth S, van der Merwe J, Yang J, Gapeshina H, Kim C, Grams J, Shi B, Wille H, Balachandran A, Schmitt-Ulms G, Safar JG, Millhauser GL, Westaway D. Octarepeat region flexibility impacts prion function, endoproteolysis and disease manifestation. EMBO Mol Med 2015; 7:339-56. [PMID: 25661904 PMCID: PMC4364950 DOI: 10.15252/emmm.201404588] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/31/2014] [Accepted: 01/08/2015] [Indexed: 12/21/2022] Open
Abstract
The cellular prion protein (PrP(C)) comprises a natively unstructured N-terminal domain, including a metal-binding octarepeat region (OR) and a linker, followed by a C-terminal domain that misfolds to form PrP(S) (c) in Creutzfeldt-Jakob disease. PrP(C) β-endoproteolysis to the C2 fragment allows PrP(S) (c) formation, while α-endoproteolysis blocks production. To examine the OR, we used structure-directed design to make novel alleles, 'S1' and 'S3', locking this region in extended or compact conformations, respectively. S1 and S3 PrP resembled WT PrP in supporting peripheral nerve myelination. Prion-infected S1 and S3 transgenic mice both accumulated similar low levels of PrP(S) (c) and infectious prion particles, but differed in their clinical presentation. Unexpectedly, S3 PrP overproduced C2 fragment in the brain by a mechanism distinct from metal-catalysed hydrolysis reported previously. OR flexibility is concluded to impact diverse biological endpoints; it is a salient variable in infectious disease paradigms and modulates how the levels of PrP(S) (c) and infectivity can either uncouple or engage to drive the onset of clinical disease.
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Affiliation(s)
- Agnes Lau
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Alex McDonald
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Nathalie Daude
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Charles E Mays
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Eric D Walter
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Robin Aglietti
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Robert C C Mercer
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Serene Wohlgemuth
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Jacques van der Merwe
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Jing Yang
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Hristina Gapeshina
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Chae Kim
- National Prion Disease Surveillance Center, Departments of Pathology and Neurology, School of Medicine Case Western Reserve University, Cleveland, OH, USA
| | - Jennifer Grams
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Beipei Shi
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada
| | - Holger Wille
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | | | - Gerold Schmitt-Ulms
- Tanz Centre for Research in Neurodegenerative Diseases, Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Jiri G Safar
- National Prion Disease Surveillance Center, Departments of Pathology and Neurology, School of Medicine Case Western Reserve University, Cleveland, OH, USA
| | - Glenn L Millhauser
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - David Westaway
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada Department of Medicine, University of Alberta, Edmonton, AB, Canada Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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64
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Puig B, Altmeppen H, Glatzel M. The GPI-anchoring of PrP: implications in sorting and pathogenesis. Prion 2015; 8:11-8. [PMID: 24509692 DOI: 10.4161/pri.27892] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The cellular prion protein (PrP(C)) is an N-glycosylated GPI-anchored protein usually present in lipid rafts with numerous putative functions. When it changes its conformation to a pathological isoform (then referred to as PrP(Sc)), it is an essential part of the prion, the agent causing fatal and transmissible neurodegenerative prion diseases. There is growing evidence that toxicity and neuronal damage on the one hand and propagation/infectivity on the other hand are two distinct processes of the disease and that the GPI-anchor attachment of PrP(C) and PrP(Sc) plays an important role in protein localization and in neurotoxicity. Here we review how the signal sequence of the GPI-anchor matters in PrP(C) localization, how an altered cellular localization of PrP(C) or differences in GPI-anchor composition can affect prion infection, and we discuss through which mechanisms changes on the anchorage of PrP(C) can modify the disease process.
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65
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Söderberg KL, Guterstam P, Langel U, Gräslund A. Targeting prion propagation using peptide constructs with signal sequence motifs. Arch Biochem Biophys 2014; 564:254-61. [PMID: 25447819 DOI: 10.1016/j.abb.2014.10.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 10/15/2014] [Accepted: 10/17/2014] [Indexed: 12/25/2022]
Abstract
Synthetic peptides with sequences derived from the cellular prion protein (PrP(C)) unprocessed N-terminus are able to counteract the propagation of proteinase K resistant prions (PrP(Res), indicating the presence of the prion isoform of the prion protein) in cell cultures (Löfgren et al., 2008). The anti-prion peptides have characteristics like cell penetrating peptides (CPPs) and consist of the prion protein hydrophobic signal sequence followed by a polycationic motif (residues KKRPKP), in mouse PrP(C) corresponding to residues 1-28. Here we analyze the sequence elements required for the anti-prion effect of KKRPKP-conjugates. Neuronal GT1-1 cells were infected with either prion strain RML or 22L. Variable peptide constructs originating from the mPrP1-28 sequence were analyzed for anti-prion effects, measured as disappearance of proteinase K resistant prions (PrP(Res)) in the infected cell cultures. We find that even a 5 amino acid N-terminal shortening of the signal peptide abolishes the anti-prion effect. We show that the signal peptide from PrP(C) can be replaced with the signal peptide from the Neural cell adhesion molecule-1; NCAM11-19, with a retained capacity to reduce PrP(Res) levels. The anti-prion effect is lost if the polycationic N-terminal PrP(C)-motif is conjugated to any conventional CPP, such as TAT48-60, transportan-10 or penetratin. We propose a mechanism by which a signal peptide from a secretory or cell surface protein acts to promote the transport of a prion-binding polycationic PrP(C)-motif to a subcellular location where prion conversion occurs (most likely the Endosome Recycling Compartment), thereby targeting prion propagation.
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Affiliation(s)
- Kajsa Löfgren Söderberg
- The Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
| | - Peter Guterstam
- The Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ulo Langel
- The Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Astrid Gräslund
- The Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
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Zhang QP, Zhang HY, Zhang XF, Zhao JH, Ma ZJ, Zhao D, Yi XN. srGAP3 promotes neurite outgrowth of dorsal root ganglion neurons by inactivating RAC1. ASIAN PAC J TROP MED 2014; 7:630-638. [DOI: 10.1016/s1995-7645(14)60106-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 05/15/2014] [Accepted: 07/15/2014] [Indexed: 11/30/2022] Open
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Rouvinski A, Karniely S, Kounin M, Moussa S, Goldberg MD, Warburg G, Lyakhovetsky R, Papy-Garcia D, Kutzsche J, Korth C, Carlson GA, Godsave SF, Peters PJ, Luhr K, Kristensson K, Taraboulos A. Live imaging of prions reveals nascent PrPSc in cell-surface, raft-associated amyloid strings and webs. ACTA ACUST UNITED AC 2014; 204:423-41. [PMID: 24493590 PMCID: PMC3912534 DOI: 10.1083/jcb.201308028] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mammalian prions refold host glycosylphosphatidylinositol-anchored PrP(C) into β-sheet-rich PrP(Sc). PrP(Sc) is rapidly truncated into a C-terminal PrP27-30 core that is stable for days in endolysosomes. The nature of cell-associated prions, their attachment to membranes and rafts, and their subcellular locations are poorly understood; live prion visualization has not previously been achieved. A key obstacle has been the inaccessibility of PrP27-30 epitopes. We overcame this hurdle by focusing on nascent full-length PrP(Sc) rather than on its truncated PrP27-30 product. We show that N-terminal PrP(Sc) epitopes are exposed in their physiological context and visualize, for the first time, PrP(Sc) in living cells. PrP(Sc) resides for hours in unexpected cell-surface, slow moving strings and webs, sheltered from endocytosis. Prion strings observed by light and scanning electron microscopy were thin, micrometer-long structures. They were firmly cell associated, resisted phosphatidylinositol-specific phospholipase C, aligned with raft markers, fluoresced with thioflavin, and were rapidly abolished by anti-prion glycans. Prion strings and webs are the first demonstration of membrane-anchored PrP(Sc) amyloids.
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Affiliation(s)
- Alexander Rouvinski
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Mays CE, Coomaraswamy J, Watts JC, Yang J, Ko KW, Strome B, Mercer RC, Wohlgemuth SL, Schmitt-Ulms G, Westaway D. Endoproteolytic processing of the mammalian prion glycoprotein family. FEBS J 2013; 281:862-76. [DOI: 10.1111/febs.12654] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 10/25/2013] [Accepted: 11/19/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Charles E. Mays
- Centre for Prions and Protein Folding Diseases; University of Alberta; Edmonton Canada
| | | | - Joel C. Watts
- Department of Biochemistry and Tanz Centre for Research in Neurodegenerative Diseases; University of Toronto; ON Canada
| | - Jing Yang
- Centre for Prions and Protein Folding Diseases; University of Alberta; Edmonton Canada
| | - Kerry W.S. Ko
- Centre for Prions and Protein Folding Diseases; University of Alberta; Edmonton Canada
| | - Bob Strome
- Department of Biochemistry and Tanz Centre for Research in Neurodegenerative Diseases; University of Toronto; ON Canada
| | - Robert C.C. Mercer
- Centre for Prions and Protein Folding Diseases; University of Alberta; Edmonton Canada
| | - Serene L. Wohlgemuth
- Centre for Prions and Protein Folding Diseases; University of Alberta; Edmonton Canada
| | - Gerold Schmitt-Ulms
- Department of Biochemistry and Tanz Centre for Research in Neurodegenerative Diseases; University of Toronto; ON Canada
| | - David Westaway
- Centre for Prions and Protein Folding Diseases; University of Alberta; Edmonton Canada
- Division of Neurology; Department of Biochemistry; University of Alberta; Edmonton Canada
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Pimenta J, Viegas A, Sardinha J, Martins IC, Cabrita EJ, Fontes CMGA, Prates JA, Pereira RMLN. NMR solution structure and SRP54M predicted interaction of the N-terminal sequence (1-30) of the ovine Doppel protein. Peptides 2013; 49:32-40. [PMID: 23973967 DOI: 10.1016/j.peptides.2013.08.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 08/12/2013] [Accepted: 08/13/2013] [Indexed: 01/29/2023]
Abstract
Prion protein (PrP(C)) biosynthesis involves a multi-step process that includes translation and post-translational modifications. While PrP has been widely investigated, for the homolog Doppel (Dpl), limited knowledge is available. In this study, we focused on a vital step of eukaryotic protein biosynthesis: targeting by the signal recognition particle (SRP). Taking the ovine Dpl (OvDpl(1-30)) peptide as a template, we studied its behavior in two different hydrophobic environments using CD and NMR spectroscopy. In both trifluoroethanol (TFE) and dihexanoyl-sn-glycero-3-phosphatidylcholine (DHPC), the OvDpl(1-30) peptide revealed to fold in an alpha-helical conformation with a well-defined central region extending from residue Cys8 until Ser22. The NMR structure was subsequently included in a computational docking complex with the conserved M-domain of SRP54 protein (SRP54M), and further compared with the N-terminal structures of mouse Dpl and bovine PrP(C) proteins. This allowed the determination of (i) common predicted N-terminal/SRP54M polar contacts (Asp331, Gln335, Glu365 and Lys432) and (ii) different N-C orientations between prion and Dpl peptides at the SRP54M hydrophobic groove, that are in agreement with each peptide electrostatic potential. Together, these findings provide new insights into the biosynthesis of prion-like proteins. Besides they also show the role of protein conformational switches in signalization toward the endoplasmic membrane, a key event of major significance in the cell cycle. They are thus of general applicability to the study of the biological function of prion-like as well as other proteins.
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Affiliation(s)
- Jorge Pimenta
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária, Quinta da Fonte Boa, Vale de Santarém, Portugal; CIISA, Faculdade de Medicina Veterinária (FMV), Universidade Técnica de Lisboa, Lisbon, Portugal
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Kretzschmar H, Tatzelt J. Prion disease: a tale of folds and strains. Brain Pathol 2013; 23:321-32. [PMID: 23587138 PMCID: PMC8029118 DOI: 10.1111/bpa.12045] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [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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Affiliation(s)
| | - Jörg Tatzelt
- NeurobiochemistryAdolf‐Butenandt‐InstituteLudwig‐Maximilians‐University MunichMunichGermany
- German Center for Neurodegenerative Diseases (DZNE)MunichGermany
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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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Kuznetsov I, Kuznetsov A. A two population model of prion transport through a tunnelling nanotube. Comput Methods Biomech Biomed Engin 2013; 17:1705-15. [DOI: 10.1080/10255842.2013.763938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Marzo L, Marijanovic Z, Browman D, Chamoun Z, Caputo A, Zurzolo C. 4-hydroxytamoxifen leads to PrPSc clearance by conveying both PrPC and PrPSc to lysosomes independently of autophagy. J Cell Sci 2013; 126:1345-54. [PMID: 23418355 DOI: 10.1242/jcs.114801] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Prion diseases are fatal neurodegenerative disorders involving the abnormal folding of a native cellular protein, named PrP(C), to a malconformed aggregation-prone state, enriched in beta sheet secondary structure, denoted PrP(Sc). Recently, autophagy has garnered considerable attention as a cellular process with the potential to counteract neurodegenerative diseases of protein aggregation such as Alzheimer's disease, Huntington's disease, and Parkinson's disease. Stimulation of autophagy by chemical compounds has also been shown to reduce PrP(Sc) in infected neuronal cells and prolong survival times in mouse models. Consistent with previous reports, we demonstrate that autophagic flux is increased in chronically infected cells. However, in contrast to recent findings we show that autophagy does not cause a reduction in scrapie burden. We report that in infected neuronal cells different compounds known to stimulate autophagy are ineffective in increasing autophagic flux and in reducing PrP(Sc). We further demonstrate that tamoxifen and its metabolite 4-hydroxytamoxifen lead to prion degradation in an autophagy-independent manner by diverting the trafficking of both PrP and cholesterol to lysosomes. Our data indicate that tamoxifen, a well-characterized, widely available pharmaceutical, may have applications in the therapy of prion diseases.
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Affiliation(s)
- Ludovica Marzo
- Institut Pasteur, Unité de Trafic Membranaire et Pathogenèse, 25 rue du Docteur Roux, 75015 Paris, France
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Schmidt C, Artjomova S, Hoeschel M, Zerr I. CSF prion protein concentration and cognition in patients with Alzheimer disease. Prion 2013; 7:229-34. [PMID: 23406922 DOI: 10.4161/pri.23904] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND/OBJECTIVE PrP (c) has been suggested to play a role in AD pathophysiology. CSF concentrations of PrP (c) have been shown to be reduced in AD compared with healthy controls. Furthermore, serum levels of PrP (c) have recently been reported to be associated with the cognitive status of healthy elderly subjects. Therefore, we hypothesized that CSF levels of PrP (c) could be associated with cognitive function of AD patients at the time of diagnosis. METHODS AD patients (n = 114) included into an observational study underwent CERAD testing and lumbar puncture at time of diagnosis / study inclusion. CSF PrP (c) was determined. Generalized linear models were fitted to assess the associations of PrP (c) plus a variety of possible confounding factors and CERAD subscale measures. RESULTS No association of CSF PrP (c) and cognitive status could be established, while other factors (i.e., use of antipsychotic drugs, use of anti-dementia drugs, female sex, pre-progression time) were related to worse cognitive function in some domains. CONCLUSION CSF PrP (c) appears not to be a useful biochemical surrogate of cognitive status in AD at the time of diagnosis. Follow-up analyses will examine possible associations with the speed of cognitive decline.
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Affiliation(s)
- Christian Schmidt
- Clinical Dementia Center, Department of Neurology, Georg-August-University, Goettingen, Germany.
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Cellular aspects of prion replication in vitro. Viruses 2013; 5:374-405. [PMID: 23340381 PMCID: PMC3564126 DOI: 10.3390/v5010374] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 01/07/2013] [Accepted: 01/16/2013] [Indexed: 12/19/2022] Open
Abstract
Prion diseases or transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative disorders in mammals that are caused by unconventional agents predominantly composed of aggregated misfolded prion protein (PrP). Prions self-propagate by recruitment of host-encoded PrP into highly ordered β-sheet rich aggregates. Prion strains differ in their clinical, pathological and biochemical characteristics and are likely to be the consequence of distinct abnormal prion protein conformers that stably replicate their alternate states in the host cell. Understanding prion cell biology is fundamental for identifying potential drug targets for disease intervention. The development of permissive cell culture models has greatly enhanced our knowledge on entry, propagation and dissemination of TSE agents. However, despite extensive research, the precise mechanism of prion infection and potential strain effects remain enigmatic. This review summarizes our current knowledge of the cell biology and propagation of prions derived from cell culture experiments. We discuss recent findings on the trafficking of cellular and pathologic PrP, the potential sites of abnormal prion protein synthesis and potential co-factors involved in prion entry and propagation.
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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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Machado CF, Beraldo FH, Santos TG, Bourgeon D, Landemberger MC, Roffé M, Martins VR. Disease-associated mutations in the prion protein impair laminin-induced process outgrowth and survival. J Biol Chem 2012; 287:43777-88. [PMID: 23132868 DOI: 10.1074/jbc.m112.428235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Prions, the agents of transmissible spongiform encephalopathies, require the expression of prion protein (PrP(C)) to propagate disease. PrP(C) is converted into an abnormal insoluble form, PrP(Sc), that gains neurotoxic activity. Conversely, clinical manifestations of prion disease may occur either before or in the absence of PrP(Sc) deposits, but the loss of normal PrP(C) function contribution for the etiology of these diseases is still debatable. Prion disease-associated mutations in PrP(C) represent one of the best models to understand the impact of PrP(C) loss-of-function. PrP(C) associates with various molecules and, in particular, the interaction of PrP(C) with laminin (Ln) modulates neuronal plasticity and memory formation. To assess the functional alterations associated with PrP(C) mutations, wild-type and mutated PrP(C) proteins were expressed in a neural cell line derived from a PrP(C)-null mouse. Treatment with the laminin γ1 chain peptide (Ln γ1), which mimics the Ln binding site for PrP(C), increased intracellular calcium in cells expressing wild-type PrP(C), whereas a significantly lower response was observed in cells expressing mutated PrP(C) molecules. The Ln γ1 did not promote process outgrowth or protect against staurosporine-induced cell death in cells expressing mutated PrP(C) molecules in contrast to cells expressing wild-type PrP(C). The co-expression of wild-type PrP(C) with mutated PrP(C) molecules was able to rescue the Ln protective effects, indicating the lack of negative dominance of PrP(C) mutated molecules. These results indicate that PrP(C) mutations impair process outgrowth and survival mediated by Ln γ1 peptide in neural cells, which may contribute to the pathogenesis of genetic prion diseases.
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Affiliation(s)
- Cleiton F Machado
- International Research Center, A. C. Camargo Hospital, and National Institute for Translational Neuroscience (CNPq/MCT/FAPESP), São Paulo 01508-010, Brazil
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Lau A, Mays CE, Genovesi S, Westaway D. RGG repeats of PrP-like Shadoo protein bind nucleic acids. Biochemistry 2012; 51:9029-31. [PMID: 23121093 DOI: 10.1021/bi301395w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Shadoo (Sho) is a central nervous system glycoprotein with characteristics similar to those of the cellular prion protein PrP(C), each containing a highly conserved hydrophobic domain (HD) and an N-terminal repeat region. Whereas PrP(C) includes histidine-containing octarepeats, the Sho region N-terminal to the HD includes tandem positively charged "RGG boxes", predicted to bind RNA. Here, we demonstrate that Sho binds DNA and RNA in vitro via this arginine-rich region.
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Affiliation(s)
- Agnes Lau
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta T6G 2M8, Canada
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80
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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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Abstract
Aggregation-prone proteins associated with neurodegenerative disease, such as α synuclein and β amyloid, now appear to share key prion-like features with mammalian prion protein, such as the ability to recruit normal proteins to aggregates and to translocate between neurons. These features may shed light on the genesis of stereotyped lesion development patterns in conditions such as Alzheimer disease and Lewy Body dementia. We discuss the qualifications of tau protein as a possible "prionoid" mediator of lesion spread based on recent characterizations of the secretion, uptake and transneuronal transfer of human tau isoforms in a variety of tauopathy models, and in human patients. In particular, we consider (1) the possibility that prionoid behavior of misprocessed tau in neurodegenerative disease may involve other aggregation-prone proteins, including PrP itself, and (2) whether "prionlike" tau lesion propagation might include mechanisms other than protein-protein templating.
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Affiliation(s)
- Garth F Hall
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA.
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Altmeppen HC, Puig B, Dohler F, Thurm DK, Falker C, Krasemann S, Glatzel M. Proteolytic processing of the prion protein in health and disease. AMERICAN JOURNAL OF NEURODEGENERATIVE DISEASE 2012; 1:15-31. [PMID: 23383379 PMCID: PMC3560451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 05/11/2012] [Indexed: 06/01/2023]
Abstract
A variety of physiological functions, not only restricted to the nervous system, are discussed for the cellular prion protein (PrP(C)). A prominent, non-physiological property of PrPC is the conversion into its pathogenic isoform (PrP(Sc)) during fatal, transmissible, and neurodegenerative prion diseases. The prion protein is subject to posttranslational proteolytic processing and these cleavage events have been shown i) to regulate its physiological functions, ii) to produce biologically active fragments, and iii) to potentially influence the course of prion disease. Here, we give an overview on the proteolytic processing under physiological and pathological conditions and critically review what is currently known about the three main cleavage events of the prion protein, namely α-cleavage, β-cleavage, and ectodomain shedding. The biological relevance of resulting fragments as well as controversies regarding candidate proteases, with special emphasis on members of the A-disintegrin-and-metalloproteinase (ADAM) family, will be discussed. In addition, we make suggestions aimed at facilitating clarity and progress in this important research field. The better understanding of this issue will not only answer basic questions in prion biology but will likely impact research on other neurodegenerative diseases as well.
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Affiliation(s)
- Hermann C Altmeppen
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf Hamburg, Germany
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84
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Alais S, Soto-Rifo R, Balter V, Gruffat H, Manet E, Schaeffer L, Darlix JL, Cimarelli A, Raposo G, Ohlmann T, Leblanc P. Functional mechanisms of the cellular prion protein (PrP(C)) associated anti-HIV-1 properties. Cell Mol Life Sci 2012; 69:1331-52. [PMID: 22076653 PMCID: PMC11114771 DOI: 10.1007/s00018-011-0879-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 10/15/2011] [Accepted: 10/24/2011] [Indexed: 12/22/2022]
Abstract
The cellular prion protein PrP(C)/CD230 is a GPI-anchor protein highly expressed in cells from the nervous and immune systems and well conserved among vertebrates. In the last decade, several studies suggested that PrP(C) displays antiviral properties by restricting the replication of different viruses, and in particular retroviruses such as murine leukemia virus (MuLV) and the human immunodeficiency virus type 1 (HIV-1). In this context, we previously showed that PrP(C) displays important similarities with the HIV-1 nucleocapsid protein and found that PrP(C) expression in a human cell line strongly reduced HIV-1 expression and virus production. Using different PrP(C) mutants, we report here that the anti-HIV-1 properties are mostly associated with the amino-terminal 24-KRPKP-28 basic domain. In agreement with its reported RNA chaperone activity, we found that PrP(C) binds to the viral genomic RNA of HIV-1 and negatively affects its translation. Using a combination of biochemical and cell imaging strategies, we found that PrP(C) colocalizes with the virus assembly machinery at the plasma membrane and at the virological synapse in infected T cells. Depletion of PrP(C) in infected T cells and microglial cells favors HIV-1 replication, confirming its negative impact on the HIV-1 life cycle.
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Affiliation(s)
- Sandrine Alais
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Ricardo Soto-Rifo
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Vincent Balter
- Université de Lyon, 69000 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
- CNRS UMR 5276 “Laboratoire de Géologie de Lyon”, Lyon, France
| | - Henri Gruffat
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Evelyne Manet
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Laurent Schaeffer
- Université de Lyon, 69000 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
- Laboratoire de Biologie Moléculaire de la Cellule (LBMC) UMR5239 CNRS/ENS/Université de Lyon/HCL, Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Jean Luc Darlix
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Andrea Cimarelli
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Graça Raposo
- Structure and Membrane Compartments and PICT-IBiSA, Institut Curie, CNRS-UMR144, 12 Rue Lhomond, 75005 Paris, France
| | - Théophile Ohlmann
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
| | - Pascal Leblanc
- Université de Lyon, 69000 Lyon, France
- Human virology department, INSERM U758, 69007 Lyon, France
- Ecole Normale Supérieure de Lyon, 69007 Lyon, France
- Laboratoire de Biologie Moléculaire de la Cellule (LBMC) UMR5239 CNRS/ENS/Université de Lyon/HCL, Ecole Normale Supérieure de Lyon, 69007 Lyon, France
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85
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Linden R, Cordeiro Y, Lima LMTR. Allosteric function and dysfunction of the prion protein. Cell Mol Life Sci 2012; 69:1105-24. [PMID: 21984610 PMCID: PMC11114699 DOI: 10.1007/s00018-011-0847-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 09/16/2011] [Accepted: 09/20/2011] [Indexed: 12/30/2022]
Abstract
Transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases associated with progressive oligo- and multimerization of the prion protein (PrP(C)), its conformational conversion, aggregation and precipitation. We recently proposed that PrP(C) serves as a cell surface scaffold protein for a variety of signaling modules, the effects of which translate into wide-range functional consequences. Here we review evidence for allosteric functions of PrP(C), which constitute a common property of scaffold proteins. The available data suggest that allosteric effects among PrP(C) and its partners are involved in the assembly of multi-component signaling modules at the cell surface, impose upon both physiological and pathological conformational responses of PrP(C), and that allosteric dysfunction of PrP(C) has the potential to entail progressive signal corruption. These properties may be germane both to physiological roles of PrP(C), as well as to the pathogenesis of the TSEs and other degenerative/non-communicable diseases.
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Affiliation(s)
- Rafael Linden
- Instituto de Biofísica Carlos Chagas Filho, UFRJ, CCS, Cidade Universitária, Rio de Janeiro, Brazil.
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86
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Chen LQ, Xiao SJ, Hu PP, Peng L, Ma J, Luo LF, Li YF, Huang CZ. Aptamer-mediated nanoparticle-based protein labeling platform for intracellular imaging and tracking endocytosis dynamics. Anal Chem 2012; 84:3099-110. [PMID: 22423600 DOI: 10.1021/ac202810b] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although nanoparticles have been widely used as optical contrasts for cell imaging, the complicated prefunctionalized steps and low labeling efficiency of nanoprobes greatly inhibit their applications in cellular protein imaging. In this study, we developed a novel and general strategy that employs an aptamer not only as a recognizer for protein recognition but also as a linker for nanoreporter targeting to specifically label membrane proteins of interest and track their endocytic pathway. With this strategy, three kinds of nanoparticles, including gold nanoparticles, silver nanoparticles, and quantum dots (QDs), have been successfully targeted to the membrane proteins of interest, such as nucleolin or prion protein (PrP(C)). The following investigations on the subcellular distribution with fluorescent immunocolocalization assay indicated that PrP(C)-aptamer-QD complexes most likely internalized into cytoplasm through a classical clathrin-dependent/receptor-mediated pathway. Further single-particle tracking and trajectory analysis demonstrated that PrP(C)-aptamer-QD complexes exhibited a complex dynamic process, which involved three types of movements, including membrane diffusion, vesicle transportation, and confined diffusion, and all types of these movements were associated with distinct phases of PrP(C) endocytosis. Compared with traditional multilayer methods, our proposed aptamer-mediated strategy is simple in procedure, avoiding any complicated probe premodification and purification. In particular, the new double-color labeling strategy is unique and significant due to its superior advantages of targeting two signal reporters simultaneously in a single protein using only one aptamer. What is more important, we have constructed a general and versatile aptamer-mediated protein labeling nanoplatform that has shown great promise for future biomedical labeling and intracellular protein dynamic analysis.
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Affiliation(s)
- Li Qiang Chen
- Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, College of Pharmaceutical Sciences, Southwest University, Chongqing 400054, People's Republic of China
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87
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da Fonseca A, Romão L, Amaral R, Assad Kahn S, Lobo D, Martins S, Marcondes de Souza J, Moura-Neto V, Lima F. Microglial stress inducible protein 1 promotes proliferation and migration in human glioblastoma cells. Neuroscience 2012; 200:130-41. [DOI: 10.1016/j.neuroscience.2011.10.025] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 10/10/2011] [Accepted: 10/14/2011] [Indexed: 12/26/2022]
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88
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89
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Abstract
Some prion protein mutations create anchorless molecules that cause Gerstmann-Sträussler-Scheinker (GSS) disease. To model GSS, we generated transgenic mice expressing cellular prion protein (PrP(C)) lacking the glycosylphosphatidyl inositol (GPI) anchor, denoted PrP(ΔGPI). Mice overexpressing PrP(ΔGPI) developed a late-onset, spontaneous neurologic dysfunction characterized by widespread amyloid deposition in the brain and the presence of a short protease-resistant PrP fragment similar to those found in GSS patients. In Tg(PrP,ΔGPI) mice, disease onset could be accelerated either by inoculation with brain homogenate prepared from spontaneously ill animals or by coexpression of membrane-anchored, full-length PrP(C). In contrast, coexpression of N-terminally truncated PrP(Δ23-88) did not affect disease progression. Remarkably, disease from ill Tg(PrP,ΔGPI) mice transmitted to mice expressing wild-type PrP(C), indicating the spontaneous generation of prions.
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90
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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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91
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Abstract
Transgenic mice expressing prion protein (PrP) molecules with several different internal deletions display spontaneous neurodegenerative phenotypes that can be dose-dependently suppressed by coexpression of wild-type PrP. Each of these deletions, including the largest one (Δ32-134), retains 9 aa immediately following the signal peptide cleavage site (residues 23-31; KKRPKPGGW). These residues have been implicated in several biological functions of PrP, including endocytic trafficking and binding of glycosaminoglycans. We report here on our experiments to test the role of this domain in the toxicity of deleted forms of PrP. We find that transgenic mice expressing Δ23-134 PrP display no clinical symptoms or neuropathology, in contrast to mice expressing Δ32-134 PrP, suggesting that residues 23-31 are essential for the toxic phenotype. Using a newly developed cell culture assay, we narrow the essential region to amino acids 23-26, and we show that mutant PrP toxicity is not related to the role of the N-terminal residues in endocytosis or binding to endogenous glycosaminoglycans. However, we find that mutant PrP toxicity is potently inhibited by application of exogenous glycosaminoglycans, suggesting that the latter molecules block an essential interaction between the N terminus of PrP and a membrane-associated target site. Our results demonstrate that a short segment containing positively charged amino acids at the N terminus of PrP plays an essential role in mediating PrP-related neurotoxicity. This finding identifies a protein domain that may serve as a drug target for amelioration of prion neurotoxicity.
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92
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Gomes MPB, Vieira TCRG, Cordeiro Y, Silva JL. The role of RNA in mammalian prion protein conversion. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 3:415-28. [PMID: 22095764 DOI: 10.1002/wrna.118] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Prion diseases remain a challenge to modern science in the 21st century because of their capacity for transmission without an encoding nucleic acid. PrP(Sc), the infectious and alternatively folded form of the PrP prion protein, is capable of self-replication, using PrP(C), the properly folded form of PrP, as a template. This process is associated with neuronal death and the clinical manifestation of prion-based diseases. Unfortunately, little is known about the mechanisms that drive this process. Over the last decade, the theory that a nucleic acid, such as an RNA molecule, might be involved in the process of prion structural conversion has become more widely accepted; such a nucleic acid would act as a catalyst rather than encoding genetic information. Significant amounts of data regarding the interactions of PrP with nucleic acids have created a new foundation for understanding prion conversion and the transmission of prion diseases. Our knowledge has been enhanced by the characterization of a large group of RNA molecules known as non-coding RNAs, which execute a series of important cellular functions, from transcriptional regulation to the modulation of neuroplasticity. The RNA-binding properties of PrP along with the competition with other polyanions, such as glycosaminoglycans and nucleic acid aptamers, open new avenues for therapy.
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Affiliation(s)
- Mariana P B Gomes
- Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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93
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Watts JC, Stöhr J, Bhardwaj S, Wille H, Oehler A, DeArmond SJ, Giles K, Prusiner SB. Protease-resistant prions selectively decrease Shadoo protein. PLoS Pathog 2011; 7:e1002382. [PMID: 22163178 PMCID: PMC3219722 DOI: 10.1371/journal.ppat.1002382] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 10/04/2011] [Indexed: 11/30/2022] Open
Abstract
The central event in prion diseases is the conformational conversion of the cellular prion protein (PrPC) into PrPSc, a partially protease-resistant and infectious conformer. However, the mechanism by which PrPSc causes neuronal dysfunction remains poorly understood. Levels of Shadoo (Sho), a protein that resembles the flexibly disordered N-terminal domain of PrPC, were found to be reduced in the brains of mice infected with the RML strain of prions [1], implying that Sho levels may reflect the presence of PrPSc in the brain. To test this hypothesis, we examined levels of Sho during prion infection using a variety of experimental systems. Sho protein levels were decreased in the brains of mice, hamsters, voles, and sheep infected with different natural and experimental prion strains. Furthermore, Sho levels were decreased in the brains of prion-infected, transgenic mice overexpressing Sho and in infected neuroblastoma cells. Time-course experiments revealed that Sho levels were inversely proportional to levels of protease-resistant PrPSc. Membrane anchoring and the N-terminal domain of PrP both influenced the inverse relationship between Sho and PrPSc. Although increased Sho levels had no discernible effect on prion replication in mice, we conclude that Sho is the first non-PrP marker specific for prion disease. Additional studies using this paradigm may provide insight into the cellular pathways and systems subverted by PrPSc during prion disease. Shadoo is a protein that resembles the prion protein, which causes prion diseases such as Creutzfeldt-Jakob disease in humans and “mad cow” disease. In this paper, we demonstrate that during prion disease in animals, levels of Shadoo were reduced in the brain and correlated with levels of infectious prions. This phenomenon occurred following infection with 14 different prion strains but was not observed following the accumulation of other aggregated proteins, including those that cause Alzheimer's disease and Parkinson's disease. Thus, Shadoo levels in the brain are a specific indicator of prion disease status, and it may be possible to exploit this observation for diagnostic purposes. Although we show that Shadoo itself is unlikely to influence prion disease, using Shadoo as a tool to probe the biology of prions may be a useful strategy for deciphering how prions damage the brain.
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Affiliation(s)
- Joel C. Watts
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, United States of America
| | - Jan Stöhr
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, United States of America
| | - Sumita Bhardwaj
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, United States of America
| | - Holger Wille
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, United States of America
- Department of Neurology, University of California, San Francisco, San Francisco, California, United States of America
| | - Abby Oehler
- Department of Pathology, University of California, San Francisco, San Francisco, California, United States of America
| | - Stephen J. DeArmond
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, United States of America
- Department of Pathology, University of California, San Francisco, San Francisco, California, United States of America
| | - Kurt Giles
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, United States of America
- Department of Neurology, University of California, San Francisco, San Francisco, California, United States of America
| | - Stanley B. Prusiner
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, United States of America
- Department of Neurology, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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94
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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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95
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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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96
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Anderson PJ, Watts H, Hille C, Philpott K, Clark P, Gentleman MCS, Jen LS. Glial and endothelial blood-retinal barrier responses to amyloid-beta in the neural retina of the rat. Clin Ophthalmol 2011; 2:801-16. [PMID: 19668434 PMCID: PMC2699783 DOI: 10.2147/opth.s3967] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The effects of an intravitreal or subretinal injection of soluble or aggregated forms of Abeta(1-42) on retinal nestin-immunoreactivity (-IR) and glial fibrillary acidic protein (GFAP)-IR in astrocytes and Müller glial cells and the integrity of the blood-retinal barrier (BRB) were tested in the in vivo rat vitreal-retinal model. Retinas were exposed for 1, 2, 3, 5 or 30 days. We present novel data demonstrating that aggregated Abeta(1-42) up-regulates nestin-IR in astrocytes and Müller cells, with a graded response directly related to the length of pre-injection aggregation time. Similar results were obtained with GFAP-IR, but the signal was weaker. An intravitreal injection of aggregated Abeta(1-42) led to VEGF-IR up-regulation, particularly in the GCL and to a lesser extent in the INL. VEGFR1-IR (Flt1) was also increased, particularly in Müller cells and this was accompanied by marked leakage of albumin into the retinal parenchyma of the injected eye, but not in the contralateral eye.
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97
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Caetano FA, Beraldo FH, Hajj GNM, Guimaraes AL, Jürgensen S, Wasilewska-Sampaio AP, Hirata PHF, Souza I, Machado CF, Wong DYL, De Felice FG, Ferreira ST, Prado VF, Rylett RJ, Martins VR, Prado MAM. Amyloid-beta oligomers increase the localization of prion protein at the cell surface. J Neurochem 2011; 117:538-53. [PMID: 21352228 DOI: 10.1111/j.1471-4159.2011.07225.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In Alzheimer's disease, the amyloid-β peptide (Aβ) interacts with distinct proteins at the cell surface to interfere with synaptic communication. Recent data have implicated the prion protein (PrP(C)) as a putative receptor for Aβ. We show here that Aβ oligomers signal in cells in a PrP(C)-dependent manner, as might be expected if Aβ oligomers use PrP(C) as a receptor. Immunofluorescence, flow cytometry and cell surface protein biotinylation experiments indicated that treatment with Aβ oligomers, but not monomers, increased the localization of PrP(C) at the cell surface in cell lines. These results were reproduced in hippocampal neuronal cultures by labeling cell surface PrP(C). In order to understand possible mechanisms involved with this effect of Aβ oligomers, we used live cell confocal and total internal reflection microscopy in cell lines. Aβ oligomers inhibited the constitutive endocytosis of PrP(C), but we also found that after Aβ oligomer-treatment PrP(C) formed more clusters at the cell surface, suggesting the possibility of multiple effects of Aβ oligomers. Our experiments show for the first time that Aβ oligomers signal in a PrP(C)-dependent way and that they can affect PrP(C) trafficking, increasing its localization at the cell surface.
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Affiliation(s)
- Fabiana A Caetano
- J. Allyn Taylor Centre for Cell Biology, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
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98
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Solomon IH, Khatri N, Biasini E, Massignan T, Huettner JE, Harris DA. An N-terminal polybasic domain and cell surface localization are required for mutant prion protein toxicity. J Biol Chem 2011; 286:14724-36. [PMID: 21385869 DOI: 10.1074/jbc.m110.214973] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
There is evidence that alterations in the normal physiological activity of PrP(C) contribute to prion-induced neurotoxicity. This mechanism has been difficult to investigate, however, because the normal function of PrP(C) has remained obscure, and there are no assays available to measure it. We recently reported that cells expressing PrP deleted for residues 105-125 exhibit spontaneous ionic currents and hypersensitivity to certain classes of cationic drugs. Here, we utilize cell culture assays based on these two phenomena to test how changes in PrP sequence and/or cellular localization affect the functional activity of the protein. We report that the toxic activity of Δ105-125 PrP requires localization to the plasma membrane and depends on the presence of a polybasic amino acid segment at the N terminus of PrP. Several different deletions spanning the central region as well as three disease-associated point mutations also confer toxic activity on PrP. The sequence domains identified in our study are also critical for PrP(Sc) formation, suggesting that common structural features may govern both the functional activity of PrP(C) and its conversion to PrP(Sc).
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Affiliation(s)
- Isaac H Solomon
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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99
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Marquer C, Devauges V, Cossec JC, Liot G, Lécart S, Saudou F, Duyckaerts C, Lévêque-Fort S, Potier MC. Local cholesterol increase triggers amyloid precursor protein-Bace1 clustering in lipid rafts and rapid endocytosis. FASEB J 2011; 25:1295-305. [PMID: 21257714 DOI: 10.1096/fj.10-168633] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Amyloid peptide (Aβ) is generated by sequential cleavage of the amyloid precursor protein (APP) by β-secretase (Bace1) and γ-secretase. Aβ production increases after plasma membrane cholesterol loading through unknown mechanisms. To determine how APP-Bace1 proximity affects this phenomenon, we developed a fluorescence lifetime imaging microscopy-Förster resonance energy transfer (FLIM-FRET) technique for visualization of these molecules either by epifluorescence or at the plasma membrane only using total internal reflection fluorescence. Further, we used fluorescence correlation spectroscopy to determine the lipid rafts partition of APP-yellow fluorescent protein (YFP) and Bace1-green fluorescent protein (GFP) molecules at the plasma membrane of neurons. We show that less than 10 min after cholesterol exposure, Bace1-GFP/APP-mCherry proximity increases selectively at the membrane and APP relocalizes to raft domains, preceded by rapid endocytosis. After longer cholesterol exposures, APP and Bace1 are found in proximity intracellularly. We demonstrate that cholesterol loading does not increase Aβ production by having a direct impact on Bace1 catalytic activity but rather by altering the accessibility of Bace1 to its substrate, APP. This change in accessibility is mediated by clustering in lipid rafts, followed by rapid endocytosis.
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Affiliation(s)
- Catherine Marquer
- Centre de Recherche de l'Institut du Cerveau et de la Moelle, UPMC, INSERM UMR-S975, Centre National de la Recherche Scientifique (CNRS) UMR7225, Hôpital de la Pitié-Salpêtrière, Paris, France
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van der Kamp MW, Daggett V. Influence of pH on the human prion protein: insights into the early steps of misfolding. Biophys J 2011; 99:2289-98. [PMID: 20923664 DOI: 10.1016/j.bpj.2010.07.063] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 07/22/2010] [Accepted: 07/27/2010] [Indexed: 01/02/2023] Open
Abstract
Transmissible spongiform encephalopathies, or prion diseases, are caused by misfolding and aggregation of the prion protein PrP. Conversion from the normal cellular form (PrP(C)) or recombinant PrP (recPrP) to a misfolded form is pH-sensitive, in that misfolding and aggregation occur more readily at lower pH. To gain more insight into the influence of pH on the dynamics of PrP and its potential to misfold, we performed extensive molecular-dynamics simulations of the recombinant PrP protein (residues 90-230) in water at three different pH regimes: neutral (or cytoplasmic) pH (∼7.4), middle (or endosomal) pH (∼5), and low pH (<4). We present five different simulations of 50 ns each for each pH regime, amounting to a total of 750 ns of simulation time. A detailed analysis and comparison with experiment validate the simulations and lead to new insights into the mechanism of pH-induced misfolding. The mobility of the globular domain increases with decreasing pH, through displacement of the first helix and instability of the hydrophobic core. At middle pH, conversion to a misfolded (PrP(Sc)-like) conformation is observed. The observed changes in conformation and stability are consistent with experimental data and thus provide a molecular basis for the initial steps in the misfolding process.
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