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Schwengler, Franziska. "Prion Diseases." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-36790.
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Apodaca, Jennifer J. "Regulation of prion protein in yeast and mammalian cells via ubiquitin mediated degradation a dissertation /." San Antonio : UTHSC, 2008. http://proquest.umi.com.libproxy.uthscsa.edu/pqdweb?did=1594496391&sid=6&Fmt=2&clientId=70986&RQT=309&VName=PQD.
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Chen, Buxin. "Prion species barrier at the short phylogenetic distances in the yeast model." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29762.
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Thesis (Ph.D)--Biology, Georgia Institute of Technology, 2009.Committee Chair: Chernoff, Yury; Committee Member: Bommarius, Andreas; Committee Member: Doyle, Donald; Committee Member: Lobachev, Kirill; Committee Member: Yi, Soojin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Pennington, Catherine Margaret. "Genetic aspects of human prion diseases." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/24216.
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Introduction: Human prion diseases are progressive, fatal neurological conditions linked to conformational changes in the structure of the prion protein. Prion diseases may be sporadic (sporadic Creutzfeldt-Jakob disease or sCJD, Sporadic Fatal Insomnia), acquired (variant CJD, iatrogenic CJD, kuru) or genetic (genetic prion disease, gPD). gPD is due to a disease-specific point or octapeptide repeat insertion (OPRI) mutation in the prion protein gene (PRNP). Numerous different PRNP mutations have been described. In some cases of gPD the phenotype may closely resemble that of sCJD, and it can be impossible to distinguish sporadic from genetic cases without genetic screening. The clinico-pathological phenotype of gPD is highly variable, both between different mutations and even within families carrying the same mutation. This variability can be partly explained by a polymorphism at codon 129 of PRNP. Codon 129 encodes either methionine or valine, and the status of both the mutated and wild-type alleles may influence disease susceptibility and phenotype. Codon 129 may also affect the manifestations of sporadic and acquired prion disease. Homozygosity for methionine at codon 129 is over-represented in both sporadic CJD (sCJD) and variant CJD (vCJD); indeed all definite or probable clinical cases of vCJD seen to date have been homozygous for methionine. Other polymorphisms of PRNP have been found in a small number of patients with sporadic and variant CJD. The significance of these polymorphisms has not been fully investigated. It is likely that other, as yet unidentified, genetic factors also play a role in influencing susceptibility to prion diseases and the clinico-pathological phenotype. A recent genome wide association study of vCJD patients found codon 129 to be the main genetic risk factor for vCJD, but did identify other candidate loci that may contribute to disease susceptibility. Work is in progress to carry out genomic screens for other, novel polymorphisms in 309 patients with sCJD and 118 patients with vCJD. Aims: The aims of the work described in this MD thesis are: 1) To review all cases of gPD on the database of the National Creutzfeldt-Jakob Disease Research and Surveillance Unit. The clinico-pathological phenotype, investigative findings and family history will be reviewed in detail. The findings will be compared with those cases of gPD previously described, in particular with cases seen in other European countries. The incidence and prevalence of these diseases in the UK will also be assessed. 2) To review cases of sCJD and vCJD with novel PRNP polymorphisms of uncertain significance. The clinico-pathological phenotype will be reviewed in detail to attempt to establish if these novel polymorphisms exert any influence over disease susceptibility or phenotype. Results: 159 cases of gPD were identified between 1970 and 2009, representing 7.8% of the prion disease (of any type) cases referred to the NCJDRSU over this time period. 17 different PRNP haplotypes were identified: P102L-129M, P105L-129V, A117V-129V, S132I-129M, Y163X, D167G-129M, D178N-129M, D178N-129V, E200K-129M, D202N-129V, V210I-129M, Q212P-129M, 2-OPRI, 4-OPRI, 5- OPRI, 6-OPRI, 7-OPRI. The clinicopathological phenotypes were highly variable and often difficult to distinguish from sCJD. The highest number of cases was caused by the 6-OPRI, most of which belonged to a single kindred. Several cases in the 4-OPRI group were found to share an additional risk allele, rsl029273C. In may be that this mutation is not pathogenic unless this risk allele is also present. This raises the possibility that other as yet unidentified genetic risk factors exist which influence gPD susceptibility and clinicopathological phenotype. Overall 61.4% of cases tested had a positive cerebrospinal fluid (CSF) 14-3-3, 90.0% an elevated SI00b, 23.1% had Magnetic Resonance Imaging (MRI) of the brain showing basal ganglia or cortical high signal, and 18.1% had an electroencephalogram (EEG) showing triphasic periodic complexes. A positive family history of prion disease was present in 57.9% of cases. Discussion: The range of point mutations and OPRI seen in the UK is considerable, but the majority of cases were due to 6-OPRI, E200K, or PI 02L. The UK differs from the rest of the world in that E200K is not the commonest mutation, due to the presence of a large British kindred with the 6-OPRI. Even within the larger kindreds, the clinicopathological phenotype remained very variable. Some distinctive features which may act as pointers towards gPD were found, such as a linear pattern of PrPSc deposition in the cerebellum seen in E200K-129M cases. Analysing the data in the smaller groups should be done with caution, and further large international studies are needed in order to truly determine the influence of factors such as codon 129 status. As with other forms of prion disease, there is an excess of individuals with methionine homozygosity at codon 129. It is unclear whether or not PRNP mutations in cis with valine at codon 129 will result in prion disease at an older age or with a different phenotype, or if these are not actually pathogenic in this genetic context. In the case of 4-OPRI, it appears that an additional risk allele is required for the development of disease, and it remains to be seen if other additional genetic factors will be found to influence disease susceptibility and phenotype. A relatively small percentage of cases had EEGs showing periodic triphasic waves, or basal ganglia or cortical high signal on MRI. CSF SI00b was more sensitive than 14-3-3, the reverse of the pattern seen in sCJD. A pattern of a negative 14-3-3 and a very high SI00b should lead to suspicions of gPD. The current diagnostic criteria for gPD are relatively strict, and may exclude some individuals who have neuropathologically confirmed prion disease (without PRNP genotyping) and several second degree relatives with gPD. This is a potential problem, especially as the neuropathological appearances cannot be relied upon to distinguish sporadic from genetic disease. Particular attention should be paid to the family history and any subtle unusual neuropathological appearances to try and reduce the risk of gPD cases being missed. In conclusion, gPD remains a difficult condition to diagnose and study. Large systematic collaborative studies are essential to increase our understanding of these rare conditions.
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Sanghera, Narinder. "The interaction of the prion protein with lipid membranes and implications for prion conversion." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247140.
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Glatzel, Markus. "Epidemiology and molecular pathology of prion diseases /." Zürich, 2003. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000253382.
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Jones, Daryl Rhys. "Treatment of prion diseases with camelid antibodies." Thesis, Royal Veterinary College (University of London), 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618290.
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Spagnolli, Giovanni. "Folding, Misfolding and Therapeutics in Prion Diseases." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/308935.
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Prion diseases are rare neurodegenerative disorders affecting humans and other animals, caused by a proteinaceous infectious agent named prion. The pivotal event in these pathologies is the conversion of PrPC, a physiologically expressed protein of poorly characterized function, into a misfolded conformer, named PrPSc, which is capable of replicating its conformationally-encoded information by inducing the conversion of its physiological counterpart. The aggregates resulting from this misfolding process accumulate in the central nervous system of affected organisms leading to neuronal death. Prion diseases are always fatal and no therapy is currently available. The lack of an effective therapeutic strategy to tackle such conditions is the result of the poor available information regarding many aspects of PrPSc, such as its structure, pathogenicity, and its replication mechanism. To complicate things further, PrPSc can appear as a set of distinct conformers, named strains, characterized by the capacity to evolve through modification and selection of their conformations, promoting resistance to treatments. In this work, we focus on two main aspects of prion biology, the elucidation of prion structure and propagation, and the development of a novel pharmacological strategy to tackle prion diseases. In both projects, we exploited the potential of integrative schemes combining computational methods and experimental data. Such approaches allowed us to build a plausible atomistic model of PrPSc and to propose a propagation mechanism describing the series of events underlying prion propagation. Moreover, the application of advanced computational schemes enabled us to identify a PrP folding intermediate displaying unique druggability properties. By exploiting the structural information of this protein conformer we identified a compound capable of acting as a pharmacological degrader for PrP by interfering with its folding pathway. Overall, this work highlights how the integration of computational and experimental methods is an extremely valuable scheme to answer complex biological questions, such as unraveling the mechanisms of protein misfolding and providing the tools to design pharmacological strategies for untreatable diseases.
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Spagnolli, Giovanni. "Folding, Misfolding and Therapeutics in Prion Diseases." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/308935.
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Prion diseases are rare neurodegenerative disorders affecting humans and other animals, caused by a proteinaceous infectious agent named prion. The pivotal event in these pathologies is the conversion of PrPC, a physiologically expressed protein of poorly characterized function, into a misfolded conformer, named PrPSc, which is capable of replicating its conformationally-encoded information by inducing the conversion of its physiological counterpart. The aggregates resulting from this misfolding process accumulate in the central nervous system of affected organisms leading to neuronal death. Prion diseases are always fatal and no therapy is currently available. The lack of an effective therapeutic strategy to tackle such conditions is the result of the poor available information regarding many aspects of PrPSc, such as its structure, pathogenicity, and its replication mechanism. To complicate things further, PrPSc can appear as a set of distinct conformers, named strains, characterized by the capacity to evolve through modification and selection of their conformations, promoting resistance to treatments. In this work, we focus on two main aspects of prion biology, the elucidation of prion structure and propagation, and the development of a novel pharmacological strategy to tackle prion diseases. In both projects, we exploited the potential of integrative schemes combining computational methods and experimental data. Such approaches allowed us to build a plausible atomistic model of PrPSc and to propose a propagation mechanism describing the series of events underlying prion propagation. Moreover, the application of advanced computational schemes enabled us to identify a PrP folding intermediate displaying unique druggability properties. By exploiting the structural information of this protein conformer we identified a compound capable of acting as a pharmacological degrader for PrP by interfering with its folding pathway. Overall, this work highlights how the integration of computational and experimental methods is an extremely valuable scheme to answer complex biological questions, such as unraveling the mechanisms of protein misfolding and providing the tools to design pharmacological strategies for untreatable diseases.
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Shi, Song. "Screening anti-prion compounds and diagnosing prion diseases by amplifying PrPSc in vitro." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-179963.
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Mahmoud, Mohamed Karmi Hussein. "Studies on pathogenic mechanisms of prion diseases and evaluation of prion strains properties." Diss., Munich Verl. Dr. Hut, 2009. http://d-nb.info/992892376/04.
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Klingeborn, Mikael. "The prion protein in normal cells and disease : studies on the cellular processing of bovine PrPC and molecular characterization of the Nor98 prion /." Uppsala : Department of Molecular Biosciences, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/2006105.pdf.
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Sun, Meng. "Development of the new yeast-based assays for prion properties." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45831.
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Prion is an infectious isoform of a normal cellular protein which is capable of converting the non-prion form of the same protein into the alternative prion form. Mammalian prion protein PrP is responsible for prion formation in mammals, causing a series of fatal and incurable prion diseases. (1) We constructed, for the first time, a two-component system to phenotypically monitor the conformational status of PrP in the yeast cells. In this system, the prion domain of Sup35 (Sup35N) was fused to PrP90-230, and the initial formation of the PrPSc-like conformation stimulated prion formation of Sup35N, which in turn converted soluble Sup35 into the prion isoform, leading to a detectable phenotype. Prion-like properties of PrP were studied in this novel yeast model system. Additionally, we employed this system to study amyloidogenic protein Aβ42 aggregation in the yeast model.
It has been suggested that the ability to form transmissible amyloids (prions) is widespread among yeast proteins and is likely intrinsic to proteins from other organisms. However, the distribution of yeast prions in natural conditions is not yet clear, which prevents us from understanding the relationship between prions and their adaptive roles in various environmental conditions. (2) We modified and developed sequence and phenotype-independent approaches for prion detection and monitoring. We employed these approaches for prion-profiling among yeast strains of various origins.
(3) Lastly, we found a prion-like state [MCS+] causing nonsense suppression in the absence of the Sup35 prion domain. Our results suggested that [MCS+] is determined by both a prion factor and a nuclear factor. The prion-related properties of [MCS+] were studied by genetic and biochemical approaches.
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Premzl, Marko, and Premzl@anu edu au premzl@excite com Marko. "Prion Protein Gene and Its Shadow." The Australian National University. The John Curtin School of Medical Research, 2004. http://thesis.anu.edu.au./public/adt-ANU20050328.164529.
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Prion protein (PrP) is best known for its involvement in prion diseases. A normal, dynamic isoform of prion protein (PrP^C) transforms into a pathogenic, compact isoform (PrP^Sc) during prion disease pathogenesis. The PrP^Sc, acting as a template upon which PrP^C molecules are refolded into a likeness of itself, accumulates in the brain neurones and causes disease. It is the only known component of prions, proteinaceous infectious particles. Both prion protein isoforms have the same primary amino acid structure and are encoded by the same prion protein gene (PRNP). PRNP determines susceptibility/disposition to prion diseases and their phenotypes.¶The normal function of PRNP is elusive. The Prnp knock-out mice with disrupted ORF show only very subtle phenotype. A number of hypotheses were proposed on the function of mammalian PRNP. The extracellular, GPI-anchored, glycosylated mammalian PrP^C expressed in a heterogenous set of cells could: transport copper from extracellular to intracellular milieu, buffer copper from synapse, contribute to redox signalling, act neuroprotectively, mediate cell-cell contacts, affect lymphocyte activation, participate in nucleic acid metabolism, be a memory molecule, and be a signal-transduction protein.¶ Experimental evidence demonstrated a redundancy between the PRNP and another, unknown gene. The critical issue therefore is to discover new genes homologous with PRNP, candidates for this redundancy. Using unpublished data, a sequence of zebrafish cDNA sequenced by Prof. Tatjana Simonics group (University of Milan, Italy), I discovered a new paralogue of PRNP. By searching manually, and in a targeted fashion, data deposited in public biological databases, I compiled support for the new human gene Shadow of prion protein (SPRN) including the direct evidence, homology-based evidence and ab initio gene prediction. The protein product called Shadoo (shadow in Japanese) is an extracellular, potentially glycosylated and GPI-anchored protein of a mature size of 100-odd amino acids. It is conserved from fish (zebrafish, Fugu, Tetraodon) to mammals (human, mouse, rat), and exhibits similarity of overall protein features with PrP. Most remarkably, the Sho is the first human/mammalian protein apart from PrP that contains the middle hydrophobic region that is essential for both normal and pathogenic properties of PrP. As this region is critical for heterodimerization of PrP, Sho may have potential to interact with PrP and is a likely candidate for the Protein X. Mammalian SPRN could be predominantly expressed in brain (Tatjana Simonic Lab, University of Milan, Italy).¶ Using the same approach to search public databases, I found, in addition, a fish duplicate of SPRN called SPRNB, and defined a new vertebrate SPRN gene family. Further, I also expanded a number of known fish genes from the PRNP gene family. The total number of the new genes that I discovered is 11. With the representatives of two vertebrate gene family datasets in hand, I conducted comparative genomic analysis in order to determine evolutionary trajectories of the SPRN and PRNP genes. This analysis, complemented with phylogenetic studies (Dr. Lars Jermiin, University of Sydney, Australia), demonstrated conservative evolution of the mammalian SPRN gene, and more relaxed evolutionary constraints acting on the mammalian PRNP gene. This evolutionary dialectic challenges widely adopted view on the highly conserved vertebrate PRNP and indicates that the SPRN gene may have more prominent function. More conserved Sprn could therefore substitute for the loss of less conserved, dispensable Prnp in the Prnp knock-out mice. Furthermore, the pathogenic potential of PRNP may be a consequence of relaxed evolutionary constraints.¶ Depth of comparative genomic analysis, strategy to understand biological function, depends on the number of species in comparison and their relative evolutionary distance. To understand better evolution and function of mammalian PRNP, I isolated and characterized the PRNP gene from Australian model marsupial tammar wallaby (Macropus eugenii). Marsupials are mammals separated from their eutherian relatives by roughly 180 million years. Comparison of the tammar wallaby and Brazilian opossum PrP with other vertebrate PrPs indicated patterns of evolution of the PrP regions. Whereas the repeat region is conserved within lineages but differs between lineages, the hydrophobic region is invariably conserved in all the PrPs. Conservation of PrP between marsupials and eutherians suggests that marsupial PrP could have the same pathogenic potential as eutherian PrPs. Using the marsupial PRNP gene in comparison with the PRNP genes from eutherian species in which prion diseases occur naturally (human, bovine, ovine) or experimentally (mouse), I defined gene regions that are conserved mammalian-wide and showed the utility of the marsupial genomic sequence for cross-species comparisons. These regions are potential regulatory elements that could govern gene expression and posttranscriptional control of mRNA activity. These findings shed new light on the normal function of mammalian PRNP supporting best the signal-transduction hypothesis. The normal function of PRNP may be triggering of signalling cascades which contribute to cell-cell interactions and may act anti-apoptotically. Yet, in the heterogenous set of cells expressing PrP^C these pathways will contribute to a number of cell-specific phenotypes, such as the synaptic plasticity and activation of lymphoid cells.
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Sidle, Kathleen Claire Louise. "Studies on the aetiology of human prion diseases." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307373.
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Come, Jon H. (Jon Harold). "Models for protein assembly in the prion diseases." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/17371.
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Wong, Edmond. "The role of PrP and Dpl in prion diseases." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614779.
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Taema, Maged M. "The in vitro characterisation of prion diseases of sheep." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12915/.
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One of the critical challenges in the transmissible spongiform encephalopathy (TSE) field is to understand the molecular basis of prion propagation and decipher the enigma of prion strains and their role in TSEs. The research approach adopted in this dissertation tackled different subjects of keen interest for prion characterisation and diagnostics. A high throughput enzyme-linked immunosorbent assay (ELISA) was developed for detection of disease-related prion protein (PrPSc) using the protease thermolysin. Thermolysin allowed isolation of protease resistant PrPSc in its full-length form, while cellular prion protein (PrPC) was digested. With further extraction and precipitation of PrPSc with sodium phosphotungstic acid (NaPTA) and in conjunction with using monoclonal antibodies that recognise distinct epitopes, PrPSc was detected and quantified successfully. Molecular strain typing of ruminant TSEs was investigated using Western blotting and depending on the resistance of PrPSc to digestion with proteinase-K (PK) and thermolysin. The methods discriminated clearly between classical ovine scrapie and experimental ovine BSE. In contrast, experimental CH1641-like isolates showed heterogenous molecular profiles. In addition, the findings from this study demonstrated the existence of thermolysin-sensitive PrP isoforms which are resistant to PK and their presence varied between individual sheep and brain regions. When studying prion propagation using the serial protein misfolding cyclic amplification (sPMCA) technique, different strains/isolates of ruminant prions were successfully amplified in vitro from as little as 0.01 ng of brain seed. Furthermore, ovine BSE was readily amplified in vitro in brain substrates from sheep with homozygous VRQ or AHQ Prnp genotype. In contrast, the CH1641 strain was refractory to such amplification. This method allowed for differentiation of experimental BSE from CH1641 prion strains within an ovine host, providing hope for the potential of sPMCA as a strain typing assay. The use of bacterially expressed recombinant PrPsen (rPrPsen) as substrate in PMCA reactions (rPrP-PMCA) was assessed. The use of the substrate improved the sensitivity, specificity, practicality and speed of sPMCA assays for detecting a range of ovine prion isolates. Expression and purification of recombinant Syrian hamster prion protein (Sha rPrP) and VRQ ovine PrP (VRQ rPrP) provided substrate for detecting PrPSc in scrapie affected brain samples. Although both substrates had the same level of sensitivity, rSha PrPsen had better specificity than VRQ rPrP. There were variations in amplification efficiency between different batches of the same rPrP. This study recommends further investigations looking at the use of a range of experimental CH1641 and BSE samples, as well as using panels of CH1641-like field isolates for sPMCA reaction to establish (such) strain typing methodology. Furthermore, applying the rPrP-PMCA assay to detect PrPSc in secreta and excreta of infected sheep in the pre-clinical phase of the disease may provide a non invasive ante-mortem test for scrapie.
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Fioriti, Luana. "The role of abnormal forms of the prion protein in the pathogenesis of inherited prion diseases." Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421998.
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Roostaee, Alireza. "Importance of dimerization in aggregation and neurotoxicity of Prion and [alpha]-Synuclein in prion and Parkinson's diseases." Thèse, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/6650.
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Abstract: Neurodegenerative diseases are associated with progressive loss of structure or function of neurons which results in cell death. Recent evidence indicate that all neurodegenerative disorders, sporadic or transmissible, may have a common pathological mechanism at the molecular level. This common feature consists of protein aggregation and accumulation of harmful aggregates in neuronal cells resulting in cellular apoptosis and neurotoxicity. Neurodegenerative diseases can affect abstract thinking, skilled movements, emotional feelings, cognition, memory and other abilities. This diverse group of diseases includes Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), prion diseases or transmissible spongiform encephalopathies (TSEs) and amyotrophic lateral sclerosis. In my project I worked on the molecular mechanism of protein aggregation, propagation and neurotoxicity in Parkinson's disease and prion disease. Prion disease and PD are associated with misfolding and aggregation of PrPc and a-Synuclein (a-Syn), respectively. Despite being two important neurodegenerative disorders, molecular mechanisms of a-Syn or PrPC aggregation and amyloidogenesis are still unclear in PD and prion disease. Furthermore, the toxic protein species in PD have not been characterized yet. In this study we characterize the mechanism of a-Syn and PrPc misfolding in a physiological-like cell free condition in the absence of a-Syn aggregates, PrPc ggregated isoform (Pre's), denaturants or acidic environment. A number of studies indicate that dimerization of PrPc or a-Syn may be a key step in the aggregation process. To test this hypothesis we verified if enforced dimerization of PrPc or a-Syn may induce a conformational change reminiscent of the conversion of PrPc or a-Syn to PrPR' or a-Syn aggregates, respectively. We used a well-described inducible dimerization strategy where a dimerizing domain called FK506-binding protein (Fv) was fused to PrPc or a-Syn in order to produce chimeric proteins Fv-PrP and a-SynF'''. A divalent ligand AP20187 was used to induce protein dimerization. Addition of AP20187 to recombinant Fv-PrP in physiological-like conditions resulted in a rapid conformational change characterized by an increase in beta-sheet (13-Sheet) structure and simultaneous aggregation of the proteins. However, non-dimerized PrP formed 13-Sheet conformation in very slower rates. In the presence of AP20187, we also report a rapid random coil into 13-sheet conformational transformation of a-SynF" within 24 h, whereas wild type a-Syn showed 24 h delay to achieve P-sheet structure after 48 h. Electron microscopy experiments demonstrated that dimerization induced amyloid fibril formation after 48 h for both Fv-PrP and a-Syr?", whereas in the absence of dimerizing ligand AP20187, PrP or a-Syn converted into amyloid fibrils after 3 days or even later. Dimerization-induced Fv-PrP aggregates were partially resistant to PK digestion which is a characteristics of the naturally occurring PrPR'. The rates of amyloidogenesis in the presence of dimerization was also characterized by Thioflavin T (ThT) fluorescence probing. Whereas the stable structure of Fv-PrP showed no ThT binding for over 60 h of incubation at 37°C, the addition of AP20187 to Fv-PrP resulted in a time-dependent increase in ThT binding. As for a-SynR, dimerization accelerated the rate of ThT binding and amyloid formation comparing to the slower amyloidogenesis rate of wild type a-Syn in the absence of dimerizer AP20187. The impact of dimerization on a-Syn aggregation was further determined by Fluorescence ANS probing, indicating a higher affinity of dimerization-induced a-SynF" aggregates for binding to ANS comparing to wild type a-Syn aggregates. These results indicate that dimerization increases the aggregation and amyloidogenesis processes for Fv-PrP and a-SynF". Both Fv-PrP and a-SynF" amyloids were successfully propagated in vitro by protein misfolding amplification (PMCA) cycle. These results ar in agreement with the theory that all protein aggregates in neurodegenerative diseases propagate with the same molecular mechanism. Neurotoxicity of recombinant Fv-PrP and a-SynF" aggregates was determined in cellulo and in vivo, respectively. Aggregates of Fv-PrP were toxic to cultured cells whilst soluble Fv-PrP and amyloid fibres were harmless to the cells. When injected to the mice brain, both a-Syni" and a-Syn pre-fibrillar aggregates internalized cells and induced neurotoxicity in the hippocampus of wild-type mice. These recombinant toxic aggregates further converted into non-toxic amyloids which were successfully amplified by PMCA method, providing the first evidence for the in vitro propagation of synthetic a-Syn aggregates. These results suggest an important role for protein dimerization in aggregation and amyloidogenesis, and therefore, in the pathology of PD and prion disease. The similarities between aggregation, amyloidogenesis and toxicity of PrPC and ct-Syn provide further evidence on the existance of a prion-like mechanism in all neurodegenerative disorders. // Résumé: Les maladies neurodégénératives sont associées à la perte progressive des propriétés structurales ou fonctionnelles des neurones, ce qui engendre la mort des cellules. De récentes études indiquent que tous les désordres neurodégénératifs, sporadiques ou transmissibles, peuvent avoir un mécanisme pathologique commun au niveau moléculaire. Ce dispositif commun se compose de l'agrégation de protéines, de la propagation des agrégats, et de l'accumulation d’agrégats toxiques dans les cellules neuronales, menant à l'apoptose et à la neurotoxicité cellulaire. Les maladies neurodégénératives peuvent affecter la pensée abstraite, les mouvements habiles, les sentiments émotifs, la connaissance, la Mémoire et d'autres capacités cognitives. Ce groupe divers de maladies inclut la maladie d'Alzheimer (AD), de Parkinson (PD), de Huntington (HD), les maladies à prions ou encéphalopathies spongiformes transmissibles (TSEs) et la sclérose latérale amyotrophique (ALS). [symboles non conformes]
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Workman, R. W. "The development candidate therapeutic and diagnostic ligands for prion diseases." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49078/.
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To date there are no effective treatments for prion diseases, and these diseases are always fatal in both humans and animals. Additionally, the gold standard for diagnosis of these disease remains to be the analysis of biopsied brain tissue obtained post mortem. Consequently, there is a continued demand for therapeutics and ante-mortem diagnostics for prion diseases. This project addresses these demands by investigating candidate therapeutic and diagnostic ligands for prion diseases. This study investigated recombinant prion proteins (rPrPs) as inhibitors in scrapie and bovine spongiform encephalopathy (BSE) in vitro amplification by protein misfolding cyclic amplification (PMCA). Three ovine rPrPs with the polymorphisms VRQ, ARQ and ARR and hamster rPrP were tested against scrapie PMCA in dilution series to calculate IC50 values. The two most potent inhibitors, VRQ and ARQ, were then similarly tested against bovine spongiform encephalopathy (BSE) amplification. The most potent inhibitor of both disease types, the ovine rPrP VRQ, was then observed to inhibit a range of different scrapie and BSE strains at a fixed concentration. It is recommended that further investigation into rPrP inhibitors is performed. Strain characterisation of scrapie was investigated using rPrP inhibitors, following observations that the rPrP inhibitors generate a pattern of inhibition at a set concentration. Although this pattern of inhibition was repeatable in scrapie amplification by PMCA, this was limited to a single round of PMCA. Ultimately, this limited the application of this method to only amplification efficient prion strains and isolates. It is recommended that this method be investigated further in combination with the amplification of different isolates in substrates of different genotypes over multiple rounds of PMCA, as well as the analysis of glycoform ratios by western blotting. Here it was also identified that the imidazole used in the elution buffer for immobilised metal affinity chromatography (IMAC) can inhibit prion amplification in a strain dependent manner. This inhibition could be used in combination with the proposed method as a multi-faceted assay of prion strain characterisation. The use of next generation phage display (NGPD) to map the epitopes of autoantibodies in the sera of scrapie infected sheep was also investigated. This was performed to identify peptides that were immunoreactive to autoantibodies specific to the disease state. The identification of diagnostic peptides would then enable the development of an ante-mortem serological diagnostic test for scrapie. NGPD successfully selected immunoreactive peptides, of which 39 were selected for validation by peptide enzyme-linked immunosorbent assays (ELISAs). Although none of the peptides demonstrated diagnostic specificity by peptide ELISA, an optimised ELISA methodology was developed for future use in the validation of NGPD selected peptides. Further variations in the NGPD method, as well as validation by immunoassay, can be investigated to identify diagnostic peptides immunoreactive to scrapie specific autoantibodies.
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Shi, Song [Verfasser], and Thomas [Akademischer Betreuer] Cremer. "Screening anti-prion compounds and diagnosing prion diseases by amplifying PrPSc in vitro / Song Shi. Betreuer: Thomas Cremer." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1068460733/34.
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Shi, Song Verfasser], and Thomas [Akademischer Betreuer] [Cremer. "Screening anti-prion compounds and diagnosing prion diseases by amplifying PrPSc in vitro / Song Shi. Betreuer: Thomas Cremer." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-179963.
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Lane, Fiona Mary. "Defining mechanisms of neurodegeneration associated with protein misfolding diseases." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/19542.
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Protein misfolding diseases (PMDs) are a broad group of disorders including Alzheimer’s, Parkinson’s and prion diseases. They are characterised by the presence of aggregated, misfolded host proteins which are thought to cause cell death. Prion diseases are associated with misfolded prion protein (PrPSc), which has a tendency to form fibrillar aggregates. By contrast, Alzheimer’s disease (AD) is associated with misfolded amyloid beta (Aβ), which aggregates to form characteristic Aβ plaques. A feature which is common across PMDs is that small assemblies (oligomers) of the misfolded proteins are thought to be the important neurotoxic species, and it has been proposed that there may be a shared mechanism leading to cell death across PMDs caused by oligomers. In this study, the toxicity of different misfolded forms of recombinant PrP (recPrP) and recombinant Aβ (recAβ) and the mechanisms leading to cell death were investigated using a primary cell culture model. In addition, the importance of the disulphide bond in recPrP in relation to oligomer formation was explored using size exclusion chromatography and mass spectrometry, the toxicity of the different resulting oligomer populations were also investigated. Both recPrP oligomers and fibrils were shown to cause toxicity to mouse primary cortical neurons. Interestingly, oligomers were shown to cause apoptotic cell death, while the fibrils did not, suggesting the activation of different pathways. By contrast, recAβ fibrils were shown to be non-toxic to cortical neurons, Aβ oligomers, however, were shown to cause toxicity. Similar to recPrP, my data showed that it is likely that recAβ 1-42 oligomers also cause apoptosis. However, by contrast this seemed to be caused by excitotoxicity, which was not found to be the case for recPrP. Additionally, I have shown that the presence or absence of the disulphide bond in PrP has a profound effect on the size of oligomers which form. RecPrP lacking a disulphide bond leads to the formation of larger oligomers which are highly toxic to primary neurons. Findings from this study suggest that structural properties such as the disulphide bond in PrP can affect the size and toxicity of oligomers, furthermore, whilst oligomers have been shown to be important in both AD and prion diseases, they may not trigger the same pathways leading to cell death.
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Zhang, Chang. "Mammalian prion toxicity studies in cytoplasmic ovine PrP transgenic Drosophila." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648399.
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Apetri, Constantin Adrian. "Folding of the Prion Protein." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1080747299.
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Allen, Charlotte Mary. "Effect of hypoxia on protein processing in Alzheimer's and prion diseases." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509820.
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Hyare, H. "Quantitative MRI in the diagnosis and monitoring of human prion diseases." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/133560/.
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This thesis examines the application of cerebral diffusion weighted imaging (DWI) and short echo time (TE) proton magnetic resonance spectroscopy (1H-MRS) for the evaluation of patients with different forms of human prion disease. Human prion diseases are progressive, uniformly fatal neurodegenerative diseases and as treatments are developed, early diagnosis is essential. Particularly important is the diagnosis of presymptomatic cases and prediction of disease onset in these individuals. In this thesis I demonstrate that MRI measures of Apparent Diffusion Coefficient (ADC) at low and high b-value and short TE 1H-MRS are potential neuroimaging biomarkers of prion disease activity. I show that ex-vivo MRI at high field provides important insights into the microstructural changes underlying the sensitivity of some of these quantitative MRI methods to prion disease pathology. The findings presented here exemplify the potential of quantitative MRI in both increasing our understanding of the pathophysiology of prion diseases and in providing neuroimaging biomarkers which will be of great importance for the future evaluation of treatment efficacy.
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Apostol, Marcin Izydor. "Towards a structural understanding of progression and transmission of prion diseases." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1590393231&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Tarozzi, Martina <1993>. "Integrating omics in prion diseases as a model to explore the strain paradigm in neurodegenerative diseases." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10204/1/MartinaTarozzi_PhDThesis.pdf.
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This project aims at deepening the understanding of the molecular basis of the phenotypic heterogeneity of prion diseases. Prion diseases represent the first and clearest example of “protein misfolding diseases”, that are all the neurodegenerative diseases caused by the accumulation of misfolded proteins in the central nervous system. In the field of protein misfolding diseases, the term “strain” describes the heterogeneity observed among the same disease in the clinical and pathologic progression, biochemical features of the aggregated protein, conformational memory and pattern of lesions. In this work, the two most common strains of Creutzfeldt-Jakob Disease (CJD), named MM1 and VV2, were analyzed. This thesis investigates the strain paradigm with the production of new multi omic data, and, on such data, appropriate computational analysis combining bioinformatics, data science and statistical approaches was performed. In this work, genomic and transcriptomic profiling allowed an improved characterization of the molecular features of the two most common strains of CJD, identifying multiple possible genetic contributors to the disease and finding several shared impaired pathways between the VV2 strain and Parkinson Disease. On the epigenomic level, the tridimensional chromatin folding in peripheral immune cells of CJD patients at onset and of healthy controls was investigated with Hi-C. While being the first application of this very advanced technology in prion diseases and one of the first in general in neurobiology, this work found a significant and diffuse loss of genomic interactions in immune cells of CJD patients at disease onset, particularly in the PRNP locus, suggesting a possible impairment of chromatin conformation in the disease. The results of this project represent a novelty in the state of the art in this field, both from a biomedical and technological point of view.
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Ghirardini, E. "THE INTERACTION BETWEEN MUTANT PRION PROTEIN AND GLUTAMATE RECEPTORS: A NOVEL MECHANISM FOR NEURONAL DYSFUNCTION IN GENETIC PRION DISEASES." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/468275.
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Genetic prion diseases are rare, invariably fatal neurodegenerative disorders linked to mutations in the PRNP gene encoding the prion protein (PrP). PRNP mutations favor the conformational conversion of PrP into a pathogenic, misfolded isoform that accumulates in the central nervous system of affected individuals and kills neurons through an unknown mechanism.
Evidence is emerging that neuronal loss in inherited prion diseases is preceded and possibly caused by synaptic dysfunctions. However, the ultimate link between synaptic dysfunction and neurodegeneration is yet to be found.
We previously demonstrated that mutant PrP is retained in the endoplasmic reticulum where it interacts with the α2-δ1 subunit of voltage-gated calcium channels. This impairs the correct delivery of the channel complex to the cell surface, impacting synaptic transmission. Nevertheless, this phenomenon alone does not account for neurodegeneration. It has been shown that PrPC engages functional interactions with other proteins that are important for synaptic function, such as glutamate receptors. Here, we aimed to explore whether intracellular retention of mutant PrP affected also the trafficking of glutamate receptors, thereby producing adverse effects on neuronal function and survival.
We found that mutant PrP impairs the membrane delivery of specific AMPA and NMDA receptor subunits, resulting in postsynaptic structural alterations and impaired basal glutamatergic transmission and synaptic plasticity. Moreover, retention of the GluA2 subunit of AMPA receptor results in exposure of GluA2-lacking, calcium-permeable AMPA receptors, leading to increased calcium permeability and enhanced sensitivity to excitotoxic cell death. Interestingly, distinct PrP mutations interact differently with glutamate receptors, altering their localization and function in different ways.
Our findings identify a new pathological mechanism for genetic prion diseases and may lead to novel therapeutic approaches for such incurable conditions.
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Stanton, James Brantly. "Identifying factors that enhance prion accumulation in cultured sheep microglial cells." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/j_stanton_082908.pdf.
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Almstedt, Karin. "Protein Misfolding in Human Diseases." Doctoral thesis, Linköpings universitet, Biokemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-21077.
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There are several diseases well known that are due to aberrant protein folding. These types of diseases can be divided into three main categories: Loss-of-function diseases Gain-of-toxic-function diseases Infectious misfolding diseases Most loss-of-function diseases are caused by aberrant folding of important proteins. These proteins often misfold due to inherited mutations. The rare disease marble brain disease (MBD) also known as carbonic anhydrase II deficiency syndrome (CADS) can manifest in carriers of point mutations in the human carbonic anhydrase II (HCA II) gene. We have over the past 10-15 years studied the folding, misfolding and aggregation of the enzyme human carbonic anhydrase II. In summary our HCA II folding studies have shown that the protein folds via an intermediate of molten-globule type, which lacks enzyme activity and the molten globule state of HCA II is prone to aggregation. One mutation associated with MBD entails the His107Tyr (H107Y) substitution. We have demonstrated that the H107Y mutation is a remarkably destabilizing mutation influencing the folding behavior of HCA II. A mutational survey of position H107 and a neighboring conserved position E117 has been performed entailing the mutants H107A, H107F, H107N, E117A and the double mutants H107A/E117A and H107N/E117A. All mutants were severely destabilized versus GuHCl and heat denaturation. Thermal denaturation and GuHCl phase diagram and ANS analyses showed that the mutants shifted HCA II towards populating ensembles of intermediates of molten globule type under physiological conditions. The enormously destabilizing effects of the H107Y mutation is not due to loss of specific interactions of H107 with residue E117, instead it is caused by long range sterical destabilizing effects of the bulky tyrosine residue. We also showed that the folding equilibrium can be shifted towards the native state by binding of the small-molecule drug acetazolamide, and we present a small molecule inhibitor assessment with select sulfonamide inhibitors of varying potency to investigate the effectiveness of these molecules to inhibit the misfolding of HCA II H107Y. We also demonstrate that high concentration of the activator compound L-His increases the enzyme activity of the mutant but without stabilizing the folded protein. The infectious misfolding diseases is the smallest group of misfolding diseases. The only protein known to have the ability to be infectious is the prion protein. The human prion diseases Kuru, Gerstmann-Sträussler-Scheinker disease (GSS) and variant Creutzfeldt-Jakob are characterized by depositions of amyloid plaque from misfolded prion protein (HuPrP) in various regions of the brain depending on disease. Amyloidogenesis of HuPrP is hence strongly correlated with prion disease. Our results show that amyloid formation of recHuPrP90-231 can be achieved starting from the native protein under gentle conditions without addition of denaturant or altered pH. The process is efficiently catalyzed by addition of preformed recHuPrP90-231 amyloid seeds. It is plausible that amyloid seeding reflect the mechanism of transmissibility of prion diseases. Elucidating the mechanism of PrP amyloidogenesis is therefore of interest for strategic prevention of prion infection.
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Edwards, Jane C. "Investigation of disease associated prion protein in blood from sheep naturally infected with scrapie." Thesis, Royal Veterinary College (University of London), 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559024.
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Farooq, Muhammad. "Use of Drosophila melanogaster to model ovine prion disease." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610654.
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Boudet-Devaud, François. "La protéine prion cellulaire : un relai de neurotoxicité commun aux protéines amyloïdes et aux nanoparticules Protective role of cellular prion protein against TNFα-mediated inlammation through TACE α-secretase PrPSc-induced PDK1 overactivation promotes the production of seedable Amyloid-β peptides in prion diseases Corruption of cellular prion protein signaling by titanium dioxide or carbon black nanoparticles promotes the accumulation of amyloid-β peptides." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCB127.
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La protéine prion cellulaire (PrPC) est une protéine majoritairement exprimée à la surface des neurones, dont la conversion transconformationnelle en prion pathogène PrPSc, est à l'origine des maladies à prions. Il est clairement établi que la neurodégénérescence induite par la PrPSc dépend de l'expression de la PrPC dans les neurones et résulte d'une déviation de la/des fonction(s) de la PrPC par la PrPSc. Identifier le rôle de la PrPC est donc un pré-requis pour aborder les mécanismes de neurodégénérescence dans les maladies à prions. Une partie de mes travaux de thèse a permis de montrer que la PrPC exerce un rôle cytoprotecteur vis-à-vis de la cytokine inflammatoire TNFalpha. L'extinction de la PrPC dans les neurones (neurones PrPnull) rend ces cellules hypersensibles au TNFalpha en raison de l'accumulation membranaire des récepteurs au TNFalpha (TNFR). Mes travaux démontrent que la perte de la fonction régulatrice de la PrPC sur l'agrégation et la signalisation des intégrines bêta 1 dans les neurones PrPnull provoque la suractivation de la kinase PDK1, l'internalisation subséquente de l'alpha-sécrétase TACE, et un découplage de TACE vis-à-vis de l'un de ses substrats, TNFR. Étant donné la proximité phénotypique entre les neurones PrPnull (Ezpeleta et al. 2017) et les neurones infectés par la PrPSc (Pietri et al. 2013 ; Alleaume-Butaux et al. 2015), mes travaux plaident en faveur d'une perte de fonction cytoprotectrice de la PrPC dans les maladies à prions. Concernant l'infection à prions, mes travaux montrent que TACE internalisée en réponse à la suractivation de PDK1 est découplée d'un autre substrat, la protéine précurseur des peptides amyloïdes (APP), ce qui mène à l'accumulation des peptides neurotoxiques Abêta 40 et Abêta 42 caractéristiques de la maladie d'Alzheimer. Dans un contexte « infection à prions », les peptides Abêta 40/42 sont présents majoritairement sous une forme monomérique, et de façon plus discrète sous forme trimérique et tétramérique. Par des approches in vitro et in vivo, nous montrons que les peptides Abêta générés par les cellules infectées par les prions ne modifient ni la réplication ni l'infectiosité des prions. Néanmoins, nous démontrons que les formes oligomérisées d'Abêta sont capables de se déposer sous forme de plaques amyloïdes dans le cerveau des souris transgéniques APP23 infectées par les prions. Dans ces souris, les dépôts d'Abêta accélèrent la pathogenèse des prions. Le dernier axe de mon travail de thèse concerne les nanoparticules, des matériaux de taille nanométrique couramment utilisés dans de nombreux produits et procédés industriels. Mes travaux mettent en évidence que, à l'instar de la PrPSc et d'Abêta, des assemblages de nanoparticules de dioxyde de titane ou de noir de carbone se lient à la PrPC exprimée à la surface des neurones et dévient sa fonction de signalisation. Cette interaction PrPC/nanoparticules provoque, entre autres, la suractivation de PDK1, l'internalisation de TACE, et l'accumulation membranaire de TNFR. Les cellules neuronales exposées aux nanoparticules deviennent alors hypersensibles au stress inflammatoire TNFalpha. Le découplage de TACE à APP induit par les nanoparticules augmente aussi la production de peptides Abêta par les neurones. Même si aucune donnée épidémiologique n'associe une exposition aux nanoparticules à la maladie d'Alzheimer, mes travaux suggèrent une implication causale des nanoparticules dans l'initiation voire l'amplification de cette maladieThe cellular prion protein (PrPC) is a protein mostly expressed at the plasma membrane of neurons. Its transconformation into the pathogenic prion PrPSc is at the root of prion diseases. It is clearly established that the PrPSc-induced neurodegeneration depends on the expression of PrPC in neurons and results from the corruption of PrPC function(s) by PrPSc. Unravelling the role of PrPC is thus a prerequisite to grasp neurodegeneration mechanisms in prion diseases. Part of my work shows that PrPC exerts a cytoprotective function against TNFalpha inflammatory cytokine. PrPC silencing in neurons (PrPnull-neurons) renders these cells highly sensitive to TNFalpha due to surface accumulation of TNFalpha receptor (TNFR). My work demonstrates that the loss of PrPC regulatory function on the clustering and signaling downstream of bêta 1 integrins in PrPnull neurons provokes the overactivation of the kinase PDK1, subsequent internalization of TACE alpha-secretase, and uncoupling of TACE from TNFR substrate. Because of the phenotypic proximity between PrPnull neurons (Ezpeleta et al. 2017) and PrPSc-infected neurons (Pietri et al. 2013; Alleaume-Butaux et al. 2015), my work supports the view of a loss of PrPC protective function in prion diseases. As concerns prion infection, my work shows that after PDK1 overactivation, internalized TACE is uncoupled from another substrate, the amyloid peptides precursor protein (APP), leading to the accumulation of neurotoxic peptides Abêta 40 and Abêta 42, hallmarks of Alzheimer's disease. Within a prion infectious context, Abêta 40/42 peptides are predominantly present as monomers, and to a lesser extent, as trimers and tetramers. By combining in vitro and in vivo approaches, we show that Abêta peptides produced by infected neurons do not alter replication nor the infectivity of prions. Nevertheless, we demonstrate that oligomerized Abêta is able to form amyloid plaques in the brain of transgenic APP23 mice infected by prions. In these mice, Abêta deposits accelerate prion pathogenesis. The last axis of my work deals with nanoparticles, that is, nanometric materials commonly found in manufactured products and industrial processes. My work shows that, as PrPSc and Abêta, titanium dioxide or carbon black assemblies interact with PrPC at the surface of neurons and deviate its signaling function, which leads, inter alia, to PDK1 overactivation, TACE internalization, TNFR accumulation at the plasma membrane, and neuronal cells hypersensitivity to TNFalpha inflammatory stress. We also found that nanoparticle-induced TACE uncoupling from APP increases Abêta peptide production by neurons. Even if no epidemiological study has demonstrated to date a link between nanoparticle exposure and Alzheimer's disease, my work suggests an causal implication of nanoparticles in the initiation or amplification of this disease
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Ezpeleta, Juliette. "Du rôle physiologique de la protéine prion cellulaire à l'infection par les prions : régulation/dérégulation du module de signalisation PDK1/TACE α-secrétase Protective role of cellular prion protein against TNFα-mediated inflammation trough TACE α-secretase Cerebellar compartmentation of prion pathogenesis Production of seedable Amyloid-β peptides in prion diseases upon PrPSc-induced PDK1 overactivation." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCB004.
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Les maladies à prions sont des maladies neurodégénératives caractérisées par l'accumulation dans le système nerveux central d'une protéine anormalement conformée et neurotoxique, la protéine prion Scrapie (PrPSc). La PrPSc est l'isoforme transconformationnelle d'une protéine normale de l'hôte, la protéine prion cellulaire (PrPC). Il est établi que la toxicité de la PrPSc est restreinte aux neurones et que la neurodégénérescence résulte d'une corruption de la/des fonction(s) physiologique(s) de la PrPC par la PrPSc. Néanmoins, nul ne sait s'il s'agit d'une perte de fonction protectrice ou d'un gain de fonction toxique de la PrPC, ou d'une combinaison des 2 événements, en partie parce que les fonctions de la PrPC restent difficiles à cerner. C'est pourquoi, identifier la/les fonction(s) de la PrPC est un prérequis pour comprendre comment la PrPSc exerce sa neurotoxicité. Mes travaux de thèse montrent pour la première fois une fonction protectrice de la PrPC vis-à-vis de la cytokine pro-inflammatoire sTNF-alpha Nous démontrons que la PrPC ajuste la sensibilité des cellules au sTNF-alpha en contrôlant le clivage des récepteurs au sTNF-alpha (TNFR1) par TACE. Au niveau mécanistique, la PrPC exerce un double contrôle sur TACE en gouvernant (i) son activité enzymatique, via le couplage de la PrPC à la NADPH oxydase/production de dérivés réactifs de l'oxygène, et (ii) sa localisation, en modulant négativement la voie de signalisation intégrines bêta-1/ROCK/PDK1, ce qui assure le maintien de TACE sous forme active à la membrane plasmique. La déplétion en PrPC provoque la micro-agrégation des intégrines bêta-1, la suractivation du duo de kinases ROCK/PDK1, et l'internalisation subséquente de l'alpha-secrétase TACE dans des microvésicules enrichies en Cavéoline-1. TACE est alors découplée de son substrat TNFR1, qui s'accumule à la membrane plasmique et rend les neurones déplétés en PrPC hypersensibles au stress inflammatoire de type sTNF-alpha. Ces mêmes défauts ont été retrouvés, avec des intensités comparables, dans les neurones infectés par les prions, ce qui appuie l'idée que la perte de la fonction cytoprotectrice de la PrPC dans les neurones vis-à-vis du sTNF-alpha participe à la progression des maladies à prions. Concernant l'infection à prions, un travail en collaboration révèle que les cellules de Purkinje du cervelet qui n'expriment pas les zébrines sont plus sensibles à la toxicité de 2 souches de prions, 22L et ME7, que celles qui expriment les zébrines. Cette étude suggère un rôle protecteur des zébrines vis-à-vis des prions. Un axe majeur de ma thèse identifie une nouvelle cible déréglée en aval du module de signalisation PDK1/TACE dans les maladies à prions, la protéine précurseur des amyloïdes (APP) avant tout connue pour son rôle dans la maladie d'Alzheimer. En abrogeant le clivage non-amyloïdogène d'APP par TACE, la PrPSc est à l'origine d'une surproduction d'Abêta40/42. Les peptides Abêta40/42 sont majoritairement sous forme monomérique, mais des formes multimériques (trimères et tétramères) d'Abêta40/42 sont aussi générées. Cette production d'Abêta40/42 dépend de la suractivation de PDK1 puisque l'inhibition pharmacologique de la kinase permet de réduire la production des peptides Abêta40/42 monomériques et rend les multimères indétectables. Il est à noter que les peptides Abêta produits ne modifient ni la réplication ni l'infectiosité de la PrPSc. Toutefois, l'Abêta40/42 généré par l'infection à prions est capable de former des dépôts dans les cerveaux de souris si, et seulement si un « seed » d'Abêta exogène a été co-transmis avec la PrPSc. De manière importante, la conjonction infection à prions/dépôts d'Abêta accélère la mort des souris infectées par les prions. Ces travaux définissent les conditions qui permettent la formation de plaques Abêta et mettent en exergue l'émergence d'une pathologie mixte causée par la présence de PrPSc et des dépôts d'Abêta dans un contexte infection à prionsPrion diseases are neurodegenerative disorders characterized by the accumulation into the central nervous system of an abnormally folded protein called Scrapie prion protein (PrPSc). PrPSc is the transconformational isoform of a ubiquitous protein of the host named cellular prion protein (PrPC). It is well established that the toxicity of PrPSc is restricted to neurons and arise from a corruption of the physiological function(s) of PrPC. However, the mechanisms by which PrPSc exerts its neurotoxicity remain poorly understood, partly because the physiological function(s) of PrPC is/are still elusive. Currently, no one knows if PrPC loses a protective role or acquires a toxic function upon its conversion into PrPSc, a combination of both events is also possible. Identifying PrPC-associated function(s) is thus a prerequisite to understand how PrPSc provokes neurodegeneration. The present work reports for the first time a protective role of PrPC towards the pro-inflammatory cytokine sTNF-alpha-associated toxicity. We show that PrPC adjusts cell sensitivity to sTNF-alpha by controlling TACE-dependent TNFR1 shedding. Mecanistically, PrPC governs both (i) TACE activity, through PrPC coupling to NADPH oxidase/Reactive Oxygen Species production, and (ii) TACE localization, by downregulating the beta-1 integrins/ROCK/PDK1 signaling pathway, thus PrPC ensures the bioavailability of an active TACE at the plasma membrane. PrPC depletion provokes the micro-aggregation of beta-1 integrins, the overactivation of ROCK and PDK1 kinases, and the subsequent internalization of TACE into Caveolin-1 enriched micro-vesicles. This leads to a defect of TNFR1 shedding, which accumulates at the plasma membrane and renders PrPC-depleted neurons highly vulnerable to sTNF-alpha insult. These alterations have also been reported in prion-infected neurons with the same intensities, supporting the view that a loss-of-the protective function of PrPC towards sTNF-alpha likely occur along prion diseases. Within a prion infectious context, a collaborative work revealed that the cerebellar Purkinje cells that do not express zebrins are highly vulnerable to the toxicity of two prion strains, 22L and ME7, compared to Purkinje cells that express zebrins. This suggest a protective role of zebrins against PrPSc-associated toxicity. A major part of my thesis identifies a new target deregulated downstream from the PDK1/TACE signaling module, the amyloid precursor protein (APP), well-known for its implication in Alzheimer's disease. By abrogating the non-amyloidogenic cleavage of APP by TACE, PrPSc provokes the overproduction of Abeta40/42 peptides. Abeta40/42 predominates as monomers but are also found as multimeric assemblies, i.e. trimers and tetramers. PrPSc-induced Abeta40/42 overproduction relates to PDK1 overactivation as pharmacological inhibition of PDK1 attenuates production of Abeta monomers and renders multimers undetectable. Of note, our work reveals that Abeta peptides do not impact on PrPSc replication nor infectivity. Nevertheless, Abeta40/42 peptides generated upon prion infection can deposit in mice brains only if an exogenous Abeta seed is co-transmitted with PrPSc. Importantly, Abeta deposition leads to early death of prion-infected mice. This work delineates the conditions that allow Abeta plaques formation and highlights the onset of a mixed-pathology caused by the co-occurrence of PrPSc and Abeta deposition within a prion infectious context
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Bamia, Aline. "Identification de nouvelles molécules anti-prions et caractérisation de leurs modes d'action." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0047.
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Le prion est un agent pathogène infectieux de nature protéique responsable de maladies neurodégénératives à la fois chez l’homme et les animaux. Le prion est responsable de la tremblante chez le mouton et la chèvre et de la maladie de Creutzfeldt-Jakob chez l’homme. Les maladies à prions sont fatales et il n’existe aucun traitement efficace de nos jours. C’est la raison pour laquelle dans mon laboratoire nous nous intéressons à l’identification de nouvelles molécules antiprions.La flunarizine a été identifiée comme étant active contre les prions [PSI+] et [URE3] de levure et contre PrPSc de mammifères in vitro, ex vivo et in vivo. L’efficacité de la flunarizine contre les prions sur tous ces modèles fait d’elle une bonne molécule candidate contre les maladies à prions. Une étude des relations structure-activité (RSA) autour de la flunarizine a été effectuée sur 47, dont 31 étaient actives contre PrPSc in vitro.Une étude des relations structure-activité (RSA) autour de la flunarizine a été effectuée sur 47, dont 31 étaient actives contre PrPSc in vitro. Six des molécules les plus actives en culture organotypique ont aussi montré leur efficacité contre PrPSc. L’effet de la flunarizine et de ses analogues contre le prion PrPSc ne dépendait pas de leurs modes d’actions connus.Les molécules les plus actives contre PrPSc inhibent la PFAR (protein folding activity of ribosome) une activité chaperon de protéines qui est impliquée dans la propagation du prion de levure [PSI+]. L’efficacité de ces molécules contre les prions fait d’elles de bons candidats pour un repositionnement thérapeutique pour les maladies à prions. Par ailleurs, nos travaux suggèrent que la PFAR pourrait être utilisée comme cible thérapeutique pour les maladies à prionsPrion is infectious protein responsible of neurodegenerative diseases in human and animal. Scrapie in goat and sheep and Creutzfeldt-Jakob disease in human are prion-related diseases. Prion diseases are fatal and to date there is no efficient treatment against these troubles. This is why in our lab we focus on identification of new compounds efficient against prions. Flunarizine was identified as new anti-prion compound efficient against yeast prion [PSI+] and [URE3], and against mammalian prion PrPSc in vitro, ex vivo and in vivo. Flunarizine may be good drug candidate against prion diseases due to its anti-prion potential in different model. Structure-activity relationship (SAR) around flunarizine hightlights 31 compounds out of 47 which inhibit prion PrPSc propagation in vitro. Six of most efficient compounds cleared prion PrPSc in organotypic slice culture. There were no relationship between flunarizine and related compound activities against prion PrPSc and their known mode of action. The most potent compounds against PrPSc inhibit PFAR (protein folding activity of ribosome). PFAR is a protein chaperon activity which is involved in yeast prion [PSI+] propagation. Many tested compounds are good candidates for drugs repurposing against prion diseases because of their important activity against PrPSc prion.Inhibition of PFAR by all the hightly effective flunarizine related compounds, suggest that PFAR may be consider as cellular target for prion related-diseases treatment
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Kissenpfennig, Adrien Nicolas. "PrP gene regulation in normal and transgenic animals." Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267442.
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Bongarzone, Salvatore. "Design, synthesis and molecular modeling studies of drug candidate compounds against prion diseases." Doctoral thesis, SISSA, 2011. http://hdl.handle.net/20.500.11767/4666.
Full textAbstract:
Prion diseases are a group of invariably fatal disorders, for which there is no cure. Despite their rare incidence in humans, prion diseases have captured very large attention from the scientific community due to the unconventional mechanism by which they are transmitted.1 The central feature of prion diseases is the accumulation in the brain and some other tissues of the diseaseassociated PrPSc, which is derived from the host-encoded cellular PrPC.1 The conversion from a normal form (PrPC) to an infectious isoform (scrapie, PrPSc) is triggered by the interaction between PrPC-PrPSc,2 as well as protein-protein interaction (PPI).3....
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Pan, Tao. "Genetic and physical interaction of Sgt2 protein with prion-chaperone machinery." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45765.
Full textAbstract:
The word "Prion" refers to self-perpetuating protein aggregates that cause neurodegenerative diseases in mammals. It is a protein isoform that has undergone a conformational change which converts the normal form of the protein into the infectious form with the same amino acid sequence.
Yeast [PSI+] prion is the prion isoform of Sup35 protein, a translation termination factor eRF3. It has been suggested that prion [PSI+] is controlled by the ensemble of chaperones with Hsp104 playing the major role. The previous work performed in the Chernoffs lab showed that the defective GET pathway caused by get led to the defect in [PSI+] curing by excess Hsp104. The GET pathway is a system responsible for transporting newly synthesized TA-protein to the ER membrane, and the components which have been proven to be involved in this pathway include: Get1, Get2, Get3, Get4, Get5 and Sgt2. In this study we describe the mechanism underlying the effect of the defective GET pathway on [PSI+]. We demonstrate that Sgt2, one of the components of GET pathway, interacts with Sup35 in both [PSI+] and [psi-] strains through its prion domain. Overproduction of Sgt2 and Hsp70-Ssa is triggered by the defective GET pathway and leads to the protection of [PSI+] aggregates from curing by excess Hsp104. We show that the direct interaction between Sgt2 and Hsp70-Ssa is not required for this protective effect.
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Sánchez, Quintero Alejandra. "Effect of congruent gastro-intestinal pathogen infection on oral prion disease susceptibility." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33225.
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Transmissible spongiform encephalopathies (TSEs) or prion diseases, are subacute neurodegenerative diseases that infect humans and animals. Many of these diseases are acquired by peripheral exposure (e.g. orally). After oral exposure prion replication within the Peyer's patches (PP) in the small intestine is necessary for the efficient spread of the disease to the brain. Within the intestine, bacteria and pathogenic microorganisms can affect the status of the gut associated lymphoid tissue (GALT). GALT consists of PP and isolated lymphoid follicles (ILF) that maintain homeostasis and protect from infections. Therefore, factors which modify GALT status, might dramatically affect oral prion disease pathogenesis by influencing the uptake of prions from the gut lumen or expanding their distribution within the host. Chronic intestinal helminth infections are common in animals and in man, and can cause significant pathology within the intestine. Little is known of the effects that intestinal helminth infections may have on oral prion diseases susceptibility. Therefore, in this study the influence that co-infection with Heligmosomoides polygyrus (a natural pathogen of the mouse small intestine) may have on oral prion disease pathogenesis and susceptibility was determined. The studies consisted of groups of 4 (for H. polygyrus characterization and for early prion detection) and 8 (for H. polygyrus-prion co-infection to terminal stage) mice infected with H. polygyrus (orally) alone or subsequently infected with ME7 scrapie prions (orally) at different time-points after parasitic infection. The effects of the H. polygyrus infection alone, and on oral prion disease pathogenesis and susceptibility were then determined. Initially the characterization of H. polygyrus infection on the host intestine revealed that this parasite caused significant pathology in the small intestine and affected the GALT microarchitecture. In the PP follicles, H. polygyrus infection increased the area of follicular dendritic cell expression, altered the positioning of mononuclear phagocytes and increased M cell density. H. polygyrus infection also reduced the number of ILF in both the small and large intestines. Additional studies in mice co-infected with a low dose of prions, revealed that these pathological changes affected the survival time and disease susceptibility. Data also show that the extent of the effects on prion disease pathogenesis and susceptibility were dependent on the stage of the helminth infection at which the mice were orally-exposed to prions. Data demonstrate that co-infection with the gastrointestinal helminth H. polygyrus can influence oral prion disease pathogenesis and susceptibility. Helminth infections can significantly modify the microarchitecture of the gut and the GALT. Data presented suggest the pathological changes that pathogens such as small intestinal helminths cause, may also influence the uptake of prions from the gut lumen after oral exposure.
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MODA, FABIO. "Engineered adeno associated-viruses expressing anti-prp molecules and polyelectrolyte gold nanoparticles as new therapeutic strategies for prion diseases in mouse models." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2010. http://hdl.handle.net/10281/19196.
Full textAbstract:
The prion diseases are neurodegenerative disorders of humans and animals that are
sporadic or inherited in origin and can be transmitted. Despite remarkable differences in phenotypic expression, these disorders share a similar pathogenic mechanism, i.e. a posttranslational modification of the prion protein from a normal cellular isoform (PrPC) to insoluble and protease-resistant disease-specific species (termed PrPSc). PrPSc accumulates in the brain and, according to prion hypothesis, is responsible for the propagation of the pathologic process and transmissibility of the disease, by converting PrPC into a likeness of itself. In a model of prion replication, direct interaction between
PrPSc template and the endogenous PrPC is proposed to drive the formation of nascent
infectious prions. For these reasons therapies to prevent prion diseases can be targeted towards the selective binding of PrPC or PrPSc and the process of conversion. Many compounds have been proposed as potential therapies in the treatment of prion diseases. With the development of novel gene delivery system and nanomedicine, it has been possible to design innovative in vitro therapies effective in cure chronically prion infected cells. ScFvD18, an antibody fragment composed by the variable regions of the heavy and light chains, already resulted in efficient clearing PrPSc in prion infected cells. Fo this reason, ScFvD18 was engineered in Adeno-Associated Viral vectors (AAVs) serotype 9
(AAV9-ScFvD18) and inoculated into the brain of prion infected mice to assess its effectiveness in modify disease progression. Also polyelectrolyte covered gold nanoparticles (AuNPs) are excellent therapeutic compounds due to the intrinsic properties as being non-toxic, inert to most chemical reactions and easy to prepare. In vitro experiments showed that even picomolar amount of AuNPs with layer-wise deposition of
oppositely charged synthetic polyelectrolytes, such as polyallylamine hydrochloride (PAH)and polystyrenesulfonate (PSS), were able to hamper the accumulation of PrPSc in cell culture. The efficacy of these nanogold particles was further assessed in prion infected
mice.
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Love, Charmaine. "PrP catabolites as determinants of TSE susceptibility." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5709.
Full textAbstract:
Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases that are characterised by long incubation periods, protein aggregation and vacuolation. During TSE pathogenesis the normal, cellular prion protein, (PrPC), which is encoded by the gene PRNP, misfolds and accumulates as abnormal disease associated prion protein, (PrPSc) within the central nervous system. Variants of the Prion protein gene are associated with susceptibility to TSE disease. For example sheep scrapie disease is modulated by several PRNP alleles, with certain alleles carried by susceptible animals being different from those carried by resistant animals. The mechanisms linking PRNP genetics and disease is poorly understood but may involve protein sequence, PrPC expression levels, and possibly differences in protein processing. Post-translational modification of PrPC leads to specific cleavage (alpha cleavage) between amino acids 115/116 of ovine PrP, producing two fragments C1 and N1. Cleavage of PrP may occur as a protective mechanism, as a response to changes in the cellular environment or as a feature of an as yet unknown biological function. In the context of TSEs, alpha cleavage may inadvertently provide a protective role by reducing available PrPC protein for conversion into PrPSc, assuming that the C1 fragment would be an inefficient substrate for conversion, the opposite theory was also proposed. The former hypothesis became the focus of this present study, with the idea that total full-length PrPC, total C1 or the ratio between full-length PrPC and C1 may be linked to differences in scrapie susceptibility. To investigate these aims the C1 fragment was measured as a percentage of total PrPC in different PRNP genotypes with varying degrees of susceptibility to scrapie and in different brain regions. This study found that PrPC alpha cleavage increased during development from the new born lamb to the adult sheep, which may have consequences for the susceptibility differences related to age. There are also variations in the amount of alpha cleavage between brain regions such as cortex and medulla that may influence scrapie strain targeting. Overall the amount of the C1 fragment in the different brain areas varied as much as 10x (range 5% to 60%). There was a significant difference in the ratio of C1 to the other PrPC forms between two PRNP genotype groups carrying the VRQ and ARQ allele but there was no correlation between C1 level and scrapie susceptibility or scrapie incubation period in our scrapie models. Alpha cleavage of PrPC also occurs in various transgenic mouse models expressing different ruminant PrP sequences. In PrPC over-expressing transgenic mouse models a higher ratio of C1 was observed, this may suggest a link between PrPC expression levels and alpha cleavage. Transgenic mice are therefore important models to further investigate the link between PrPC biology and scrapie disease phenotype. In conclusion, this thesis has shown for the first time that certain ovine PRNP alleles can influence alpha cleavage of the PrPC protein; however it appears not to be a significant indicator of TSE disease susceptibility in sheep.
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Urrea, Zazurca Laura. "Funciones de la proteína priónica celular, alfa-sinucleína y reelina en enfermedades neurodegenerativas." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/482168.
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Las enfermedades neurodegenerativas son una serie de trastornos del sistema nervioso caracterizadas por la pérdida de grupos neuronales específicos y por la presencia de cuerpos de inclusión proteicos, entre ellas las más frecuentes son la enfermedad de Alzheimer y la enfermedad de Parkinson, ambas asociadas a la edad. Su etiología, en la mayoría de los casos, aún se desconoce y su manifestación clínica es progresiva y crónica.
La enfermedad de Parkinson se caracteriza por la pérdida de neuronas dopaminérgicas de la sustancia nigra pars compacta y por la presencia de agregados intracitoplasmáticos, denominados cuerpos de Lewy (LB). Se ha identificado la α-sinucleína como el principal componente de los LB, su forma desplegada está involucrada en el proceso patológico de la EP. La α-sinucleína desplegada, se agrega para formar protofibrillas que finalmente darán lugar a los LB. La acumulación intracelular de proteínas anormales da lugar al concepto de proteinopatías. Se cree que estas proteínas anómalas son capaces de propagarse entre células. Varios mecanismos moleculares se han propuesto para la transmisión de α-sinucleína, en este caso estudiamos la proteína priónica celular (PrPc) como posible receptor de α-sinucleína.
PrPc es conocida por su participación en las enfermedades priónicas en su forma patológica, llamada PrPsc. Esta forma PrPsc se agrega y forma placas en el cerebro. Se ha demostrado que la PrPc es capaz de unirse a péptidos amiloides como los oligómeros β-amiloides que se encuentran en la enfermedad de Alzheimer. En esta tesis estudiamos el transporte de α-sinucleína según la dosis genética de PrPc. Después de realizar inoculaciones intracraneales con protofibrillas de α-sinucleína en animales con distintas dosis génica de PrPc, se observa que los animales sobreexpresantes de la PrPc presentan más agregados de α-sinucleína fosforilada que los animales deficientes de PrPc. Además, también identificamos la región de unión entre PrPc y α-sinucleína. Gracias a las construcciones delecionadas de PrPc detectamos que la región del dominio central cargada es esencial para la unión con α-sinucleína.
Además, en esta tesis hemos analizado los niveles de Reelina en distintas enfermedades neurodegenerativas. Reelina es una proteína secretable implicada en el neurodesarrollo. En el adulto, Reelina está involucrada en la plasticidad sináptica, aprendizaje y memoria. Se ha detectado que niveles bajos de Reelina da lugar a fallos en la sinapsis y neurodegeneración. Anteriormente, los niveles de Reelina se han analizado en muestras humanas, sobretodo, en la enfermedad de Alzheimer dando lugar a resultados contradictorios. En el presente estudio, determinamos los cambios del mRNA y proteicos de Reelina en la enfermedad de Alzheimer, la demencia por cuerpos de Lewy, la enfermedad de Parkinson y en la enfermedad Creutzfeldt-Jakob (CJD) esporádica. Mientras los niveles proteicos de Reelina descienden en la enfermedad de Alzheimer y en la demencia por cuerpos de Lewy, en la enfermedad de Parkinson se mantienen. Por otro lado, detectamos que los niveles de Reelina en CJD aumentan, sobretodo en los casos tipo 1. Animales sobreexpresantes de PrPc humana inoculados con extracto cerebral de CJD también presentan un aumento de sus niveles de Reelina. In vitro, se observa que la expresión de Reelina aumenta en presencia del prion sintético que imita la secuencia central de la PrPc humana. Además, el aumento de Reelina es dependiente de las especies reactivas de oxígeno (ROS), mediante el uso de inhibidores de ROS detectamos como los niveles de Reelina se mantienen.Many neurodegenerative diseases are characterized by the loss of neurons and intracellular accumulation of abnormal proteins, with the formation of inclusion bodies. Parkinson’s disease (PD) is the second most common form of neurodegenerative diseases. PD shows an abnormal accumulation of α-synuclein aggregates in neurons, called Lewy bodies (LB). Several groups have reported that abnormal form of α-synuclein can propagate through the cells and, consequently, form inclusions. Thus, it has been suggested different molecular mechanisms involved in α-synuclein propagation. It has been reported that cellular prion protein (PrPc) is a receptor of β-amyloid. In this study, we analyse whether the PrPc is a receptor for α-synuclein. Animals with different PrPc expression were intracranially injected with α-synuclein protofibrils. We observe that PrPc expression is not mandatory for α-synuclein propagation, but PrPc-overexpressing mice show more aggregates than in PrPc absence. Moreover, charge cluster domain of PrPc is essential for α-synuclein binding. In addition, we study Reelin levels in different neurodegenerative diseases. Reelin is a glycoprotein that is crucial for the correct cytoarchitectonic organization of the developing Central Nervous System. Decreased levels of Reelin lead to synaptic dysfunction or neurodegeneration. In the present study, we analyse the changes in Reelin and Reln mRNA in Alzheimer’s disease, Dementia with Lewy Bodies (DLB), Parkinson´s disease (PD) and sporadic Creutzfeldt-Jakob disease (sCJD). Meanwhile, inmunoblot results indicate decreased levels of Reelin in AD and DLB, PD do not show changes. In contrast, it has been detected an increase in sCJD(I). Reelin increased levels depends on reactive oxygen species (ROS). Using inhibitors of ROS production, as DPI and NAC, Reelin levels are maintained.
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Wooldridge, Marion Joan Anstee. "A study of the incubation period, or age at onset, of the transmissible spongiform encephalopathies/prion diseases." Thesis, London School of Hygiene and Tropical Medicine (University of London), 1995. http://researchonline.lshtm.ac.uk/682220/.
Full textAbstract:
In order to model epidemics of infectious diseases, particularly to estimate probable numbers of cases with onset at any particular time, it is necessaiy to incorporate a term for the incubation period frequency distribution. Sartwell's hypothesis states that the incubation period frequency distribution for infectious disease is generally a log-normal distribution, based on his examination of disease with short incubation periods. However, it may not apply to diseases with long incubation periods. During the course of an epidemic of a disease with a long incubation period, left and right censoring makes direct observation of the frequency distribution highly unreliable; in addition, time of infection is often unknown. Therefore, for a previously undescribed disease, methods other than direct observation must be employed. One method is to extrapolate from information available for other diseases. In evaluation of Sartwell's hypothesis as applied to diseases with long incubation periods, examination of transfijsion-associated AIDS data was inconclusive. Examination of data for experimental transmissible spongiform encephalopathy (TSE)/prion disease in several species suggests that it may not apply. For natural TSE/prion disease, age at onset is used generally as a 'proxy' for incubation period since infection time is rarely known; the validity of this may vary with the disease type and species being examined. Using this measure, again Sartwell's hypothesis was not confirmed. For both incubation period and age at onset, evidence presented suggests that observed frequency distribution coefficient of skewness is associated with modal age at onset (and thus indirectly with prior age at infection, where appropriate), an earlier modal age at onset resulting in a larger observed coefficient of skewness. The relationship of this association with Sartwell's findings is discussed; they are not incompatible. In addition, an association between observed coefficient of skewness and sample size is demonstrated and the implications discussed.
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Rey, Clémence. "Single chain antibodies against the 37 kDa/67 kDa laminin receptor as tools for prion diseases therapy." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-48326.
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Lenuzza, Natacha. "Modélisation de la réplications des Prions : Implication de la dépendance en taille des agrégats de PrP et de l'hétérogénéité des populations cellulaires." Phd thesis, Ecole Centrale Paris, 2009. http://tel.archives-ouvertes.fr/tel-00453321.
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Les maladies à Prions sont des maladies neurodégénératives fatales, touchant l'homme et l'animal. Même si le risque de transmission de la maladie de la vache folle à l'homme semble maîtrisé, il persiste actuellement un risque de santé publique lié à la transmission iatrogène de cette forme, notamment par transfusion sanguine. Pour contrôler cette transmission, il est donc essentiel de mieux comprendre les mécanismes moléculaires et cellulaires de réplication et de dissémination des Prions. Ces mécanismes de réplication se produisent à des échelles de temps et de taille difficilement accessibles expérimentalement, et ont ainsi fait l'objet de nombreuses modélisations théoriques utiles pour aider à la compréhension des mécanismes. L'objectif de cette thèse est de compléter ces modèles mathématiques, afin d'étudier plus spécifiquement les conséquences dynamiques sur la réplication des Prions, des propriétés de réplication taille-dépendante d'une part, et de l'hétérogénéité des cellules impliquées dans la réplication d'autre part. Dans un premier temps, nous avons généralisé un modèle de polymérisation nucléée pour prendre en compte un taux d'élongation des fibrilles dépendant de leur taille. Nous avons principalement déduit de cette étude que la distribution en taille des agrégats semble une donnée expérimentale très informative sur les mécanismes élémentaires de réplication, au contraire du profil cinétique d'accumulation de la PrPres peu sensibles aux propriétés de réplication taille-dépendantes. Dans un second temps, après une caractérisation expérimentale de l'hétérogénéité cellulaire de réplication, nous avons intégré le mécanisme de réplication intracellulaire à un modèle multicellulaire par automate cellulaire continu stochastique. De manière appliquée, cette étude nous a permis d'identifier des étapes du processus de culture cellulaire critiques pour l'établissement d'une infection chronique, et nous a permis de proposer plusieurs protocoles pour augmenter la sensibilité des cultures cellulaires aux infections à Prions.
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Mai, Phuong Thao. "The potential role of copper binding sites in prion propagation." Doctoral thesis, SISSA, 2014. http://hdl.handle.net/20.500.11767/3905.
Full textAbstract:
Transmissible spongiform encephalopathies (TSEs) or prion diseases are caused by a post-translational conversion of the normal cellular form of the prion protein (PrPC) into the pathological and infectious isoform denoted as prion or PrPSc. PrPC has been shown as a high-affinity copper-binding protein, and to a lesser extent binding to other divalent cations through the octarepeat region (OR) and the non-OR copper binding sites located in the disordered N-terminal domain. Studies on the role of copper in promoting prion conversion and infectivity yielded controversial results. In this work, we explored the role of histidine residues which are crucial for copper coordination in prion conversion using a combination of cell culture and cell-free approaches. The first evidence was derived from chronically prion-infected neuronal murine cells (ScN2a) transiently expressed in murine PrPC carrying artificial mutations at histidines located both at the OR and non-OR regions. We found that the lack of each histidine in the OR has neither effect on prion replication nor protein maturation and trafficking. Intriguingly, mutagenesis of histidine 95 (H95Y) does enhance prion conversion leading to de novo infectious material formation and cause aberrant accumulation during protein trafficking. Thus, we hypothesize that H95 could function as molecular switch for prion conversion, and copper bound to this residue may function in protein conformation stabilization. We also propose a cellular model for prion formation in cells expressing the H95Y mutant. Interestingly, our data may establish a platform for rationally designed experiments aimed at elucidating whether the H95Y mutation may cause de novo prion diseases in transgenic mice.
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Brown, Karen L. "Influence of the immune system on peripherally acquired transmissible spongiform encephalopathy infection with special reference to the role of the follicular dendritic cell." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4376.
Full textAbstract:
The Transmissible Spongiform Encephalopathies (TSEs) or “prion” diseases are a group of fatal neurodegenerative diseases the aetiology of which is not fully understood. These diseases are characterised by a number of pathological changes in the central nervous system (CNS) including; vacuolation of the neuropil, gliosis and deposition of PrPSc; the abnormal form of the host glycoprotein PrP. Although the major pathology in these diseases is associated with the CNS the immune system is central to the pathogenesis of many natural and experimental TSEs including natural scrapie in sheep, chronic wasting disease in free ranging and captive deer and variant CJD (vCJD) in humans. Unlike many infectious diseases where deficiencies in immune function are opportunistic for the invading pathogen a competent immune system is required for efficient TSE infection via peripheral routes. As infection of the lymphoid tissues in many TSEs can occur many months before the detection of infectivity in the CNS, the determination of those cells in the lymphoid system has been the focus of much research and a number of studies now point towards the importance of the follicular dendritic cell (FDC), a long-lived radio resistant cell, in TSE pathogenesis. The involvement of FDCs in peripheral TSE pathogenesis relates to the inability of ionising radiation to influence pathogenesis, the association of PrP protein with FDCs in both uninfected and infected lymphoid tissues, and the demonstration that TSE pathogenesis is severely impaired in mice devoid of these cells. The aims of this thesis were to further understand the role of FDCs in the pathogenesis of a range of mouse-adapted experimental TSE strains and to determine if peripherally acquired TSE infections are influenced by host age or by stimulation of the immune system. Using chimaeric mouse models where a mismatch in the expression of PrP protein between FDCs and lymphoid/myeloid cells was produced, further evidence for a critical role for in the pathogenesis of the ME7 TSE strain was produced. Although these findings produced strong evidence that FDCs were important for the ME7 strain the possibility that different TSE strains may target different cell types in the peripheral lymphoid system was explored using a range of mice with specific immunological defects. Infection of these mice with several experimental TSE strains showed that the presence of mature FDCs was also important for the pathogenesis of the strains tested. Clinical cases of vCJD have been confined almost exclusively to young adults, although the reasons behind this apparent age-related susceptibility are not fully understood. The capacity of the immune system to mediate immune responses to pathogens declines with age as a result of impaired lymphocyte and FDC function. As FDCs are critically involved in the pathogenesis of many TSEs, including vCJD, it was hypothesised that an aging immune system may impair disease pathogenesis. Peripheral infection of senescent mice failed to produce clinical disease during lifespan, although evidence of disease transmission, was detected in a proportion of aged mice. These findings demonstrate that this inefficient disease transmission, as a consequence of age, may lead to considerable levels of sub-clinical disease within the population. Finally the influence of immune system stimulation, by the generation of a humoral immune response, on peripheral TSE pathogenesis was investigated. These findings demonstrated that immunisation can influence pathogenesis, but only during the early stages of infection prior to spread to the CNS. These data imply that modulation of the immune system does not alter TSE pathogenesis once disease has been initiated in the CNS. Finally, these studies have found some preliminary evidence that TSE infection may induce FDC activation suggesting that TSE infection may influence the immune response. Together, these data show that a functional immune system and specifically, the presence of mature FDCs, are central to the pathogenesis of peripherally acquired TSE infections.