451
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Non-esterified fatty acids generate distinct low-molecular weight amyloid-β (Aβ42) oligomers along pathway different from fibril formation. PLoS One 2011; 6:e18759. [PMID: 21526230 PMCID: PMC3079704 DOI: 10.1371/journal.pone.0018759] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Accepted: 03/09/2011] [Indexed: 12/13/2022] Open
Abstract
Amyloid-β (Aβ) peptide aggregation is known to play a central role in the etiology of Alzheimer’s disease (AD). Among various aggregates, low-molecular weight soluble oligomers of Aβ are increasingly believed to be the primary neurotoxic agents responsible for memory impairment. Anionic interfaces are known to influence the Aβ aggregation process significantly. Here, we report the effects of interfaces formed by medium-chain (C9–C12), saturated non-esterified fatty acids (NEFAs) on Aβ42 aggregation. NEFAs uniquely affected Aβ42 aggregation rates that depended on both the ratio of Aβ:NEFA as well the critical micelle concentration (CMC) of the NEFAs. More importantly, irrespective of the kind of NEFA used, we observed that two distinct oligomers, 12–18 mers and 4–5 mers were formed via different pathway of aggregation under specific experimental conditions: (i) 12–18 mers were generated near the CMC in which NEFAs augment the rate of Aβ42 aggregation towards fibril formation, and, (ii) 4–5 mers were formed above the CMC, where NEFAs inhibit fibril formation. The data indicated that both 12–18 mers and 4–5 mers are formed along an alternate pathway called ‘off-pathway’ that did not result in fibril formation and yet have subtle structural and morphological differences that distinguish their bulk molecular behavior. These observations, (i) reflect the possible mechanism of Aβ aggregation in physiological lipid-rich environments, and (ii) reiterate the fact that all oligomeric forms of Aβ need not be obligatory intermediates of the fibril formation pathway.
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452
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Saunders SE, Yuan Q, Bartz JC, Bartelt-Hunt S. Effects of solution chemistry and aging time on prion protein adsorption and replication of soil-bound prions. PLoS One 2011; 6:e18752. [PMID: 21526178 PMCID: PMC3079715 DOI: 10.1371/journal.pone.0018752] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 03/17/2011] [Indexed: 11/18/2022] Open
Abstract
Prion interactions with soil may play an important role in the transmission of chronic wasting disease (CWD) and scrapie. Prions are known to bind to a wide range of soil surfaces, but the effects of adsorption solution chemistry and long-term soil binding on prion fate and transmission risk are unknown. We investigated HY TME prion protein (PrP(Sc)) adsorption to soil minerals in aqueous solutions of phosphate buffered saline (PBS), sodium chloride, calcium chloride, and deionized water using western blotting. The replication efficiency of bound prions following adsorption in these solutions was also evaluated by protein misfolding cyclic amplification (PMCA). Aging studies investigated PrP(Sc) desorption and replication efficiency up to one year following adsorption in PBS or DI water. Results indicate that adsorption solution chemistry can affect subsequent prion replication or desorption ability, especially after incubation periods of 30 d or longer. Observed effects were minor over the short-term (7 d or less). Results of long-term aging experiments demonstrate that unbound prions or prions bound to a diverse range of soil surfaces can readily replicate after one year. Our results suggest that while prion-soil interactions can vary with solution chemistry, prions bound to soil could remain a risk for transmitting prion diseases after months in the environment.
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Affiliation(s)
- Samuel E. Saunders
- Department of Civil Engineering, University of Nebraska-Lincoln, Peter Kiewit Institute, Omaha, Nebraska, United States of America
| | - Qi Yuan
- Department of Civil Engineering, University of Nebraska-Lincoln, Peter Kiewit Institute, Omaha, Nebraska, United States of America
| | - Jason C. Bartz
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Shannon Bartelt-Hunt
- Department of Civil Engineering, University of Nebraska-Lincoln, Peter Kiewit Institute, Omaha, Nebraska, United States of America
- * E-mail:
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453
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El Moustaine D, Perrier V, Van Ba IAT, Meersman F, Ostapchenko VG, Baskakov IV, Lange R, Torrent J. Amyloid features and neuronal toxicity of mature prion fibrils are highly sensitive to high pressure. J Biol Chem 2011; 286:13448-59. [PMID: 21357423 PMCID: PMC3075691 DOI: 10.1074/jbc.m110.192872] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 02/24/2011] [Indexed: 12/22/2022] Open
Abstract
Prion proteins (PrP) can aggregate into toxic and possibly infectious amyloid fibrils. This particular macrostructure confers on them an extreme and still unexplained stability. To provide mechanistic insights into this self-assembly process, we used high pressure as a thermodynamic tool for perturbing the structure of mature amyloid fibrils that were prepared from recombinant full-length mouse PrP. Application of high pressure led to irreversible loss of several specific amyloid features, such as thioflavin T and 8-anilino-1-naphthalene sulfonate binding, alteration of the characteristic proteinase K digestion pattern, and a significant decrease in the β-sheet structure and cytotoxicity of amyloid fibrils. Partial disaggregation of the mature fibrils into monomeric soluble PrP was observed. The remaining amyloid fibrils underwent a change in secondary structure that led to morphologically different fibrils composed of a reduced number of proto-filaments. The kinetics of these reactions was studied by recording the pressure-induced dissociation of thioflavin T from the amyloid fibrils. Analysis of the pressure and temperature dependence of the relaxation rates revealed partly unstructured and hydrated kinetic transition states and highlighted the importance of collapsing and hydrating inter- and intramolecular cavities to overcome the high free energy barrier that stabilizes amyloid fibrils.
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Affiliation(s)
- Driss El Moustaine
- From the University of Montpellier 2 and
- INSERM, U710, Montpellier F-34095, France
- Ecole Pratique des Hautes Études, Paris F-75007, France
| | - Veronique Perrier
- From the University of Montpellier 2 and
- INSERM, U710, Montpellier F-34095, France
- Ecole Pratique des Hautes Études, Paris F-75007, France
| | - Isabelle Acquatella-Tran Van Ba
- From the University of Montpellier 2 and
- INSERM, U710, Montpellier F-34095, France
- Ecole Pratique des Hautes Études, Paris F-75007, France
| | - Filip Meersman
- the Department of Chemistry, Katholieke Universiteit Leuven, Leuven B-3001, Belgium, and
| | - Valeriy G. Ostapchenko
- the Center for Biomedical Engineering and Technology, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Ilia V. Baskakov
- the Center for Biomedical Engineering and Technology, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Reinhard Lange
- From the University of Montpellier 2 and
- INSERM, U710, Montpellier F-34095, France
- Ecole Pratique des Hautes Études, Paris F-75007, France
| | - Joan Torrent
- From the University of Montpellier 2 and
- INSERM, U710, Montpellier F-34095, France
- Ecole Pratique des Hautes Études, Paris F-75007, France
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454
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Somerville RA, Gentles N. Characterization of the effect of heat on agent strains of the transmissible spongiform encephalopathies. J Gen Virol 2011; 92:1738-1748. [PMID: 21471321 DOI: 10.1099/vir.0.030452-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The causal agents of the transmissible spongiform encephalopathy (TSE) diseases, sometimes called prion diseases, are characterized by high resistance to inactivation with heat. Results from thermal inactivation experiments on nine TSE strains, seven passaged in two PrP genotypes, showed differences in sensitivity to heat inactivation ranging over 17 °C. In addition, the rate of inactivation with increasing temperature varied between TSE models. In some cases passage in an alternative PrP genotype had little effect on the resulting inactivation properties, but for others the infectious agent was inactivated at lower temperatures. No strain with higher thermostability properties was selected. The effect of mixing two TSE strains, to see whether their properties were affected through interaction with each other, was also examined. The results showed that both strains behaved as expected from the behaviour of the unmixed controls, and that the strain responsible for inducing TSE disease could be identified. There was no evidence of a direct effect on intrinsic strain properties. Overall, the results illustrate the diversity in properties of TSE strains. They require intrinsic molecular properties of TSE agents to accommodate high resistance to inactivation and a mechanism, independent of the host, to directly encode these differences. These findings are more readily reconciled with models of TSE agents with two separate components, one of which is independent of the host and comprises a TSE-specific nucleic acid, than with models based solely on conformational changes to a host protein.
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Affiliation(s)
- Robert A Somerville
- Neuropathogenesis Division, The Roslin Institute and Royal (Dick) Veterinary School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian, EH25 9PS, Scotland, UK
| | - Nicola Gentles
- Neuropathogenesis Division, The Roslin Institute and Royal (Dick) Veterinary School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian, EH25 9PS, Scotland, UK
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455
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Hafner-Bratkovič I, Jerala R. Disulfide mapping reveals the domain swapping as the crucial process of the structural conversion of prion protein. Prion 2011; 5:56-9. [PMID: 21555920 DOI: 10.4161/pri.5.2.16232] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Prion diseases are infectious conformational diseases. Despite the determination of many native prion protein (PrP) structures and in vitro production of infectious prions from recombinant PrP the structural background of PrP conversion remains the largest unsolved problem. The aggregated state of PrP (Sc) makes it inaccessible to high resolution techniques, therefore indirect methods have to be used to investigate the conversion process. We engineered disulfide bridges into the structured domain of PrP in order to determine the secondary structure elements that remain conserved upon conversion. Rather surprisingly, introduction of disulfides into each or both of the subdomains B1-H1-B2 and H2-H3 of the C-terminal globular domain retained the robust ability to convert into fibrils with increased content of β-structure, indistinguishable from the wild-type PrP. On the other hand disulfide bridges tethering the two subdomains completely prevented conversion, while their reduction reversed their conversion ability. The same conversion propensity was replicated also in prion infected cell lines. Experiments with combinations of engineered cysteine residues further support that domain swapping, centered on the B2-H2 loop, previously associated to species barrier, leads to PrP swapped dimers as the building block of prion fibrils.
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Affiliation(s)
- Iva Hafner-Bratkovič
- Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia
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456
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Piro JR, Supattapone S. Photodegradation illuminates the role of polyanions in prion infectivity. Prion 2011; 5:49-51. [PMID: 21646861 DOI: 10.4161/pri.5.2.16155] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Understanding the mechanism by which prion infectivity is encoded by the misfolded protein PrP (Sc ) remains a high priority within the prion field. Work from several groups has indicated cellular cofactors may be necessary to form infectious prions in vitro. The identity of endogenous prion conversion cofactors is currently unknown, but may include polyanions and/or lipid molecules. In a recent study, we manufactured infectious hamster prions containing purified PrP (Sc) , co-purified lipid, and a synthetic photocleavable polyanion. The polyanion was incorporated into infectious PrP (Sc) complexes, and then specifically degraded by exposure to ultraviolet light. Light-induced in situ degradation of the incorporated polyanion had no effect on the specific infectivity of the samples as determined by end-point dilution sPMCA and scrapie incubation time assays. Furthermore, prion strain properties were not changed by polyanion degradation, suggesting that intact polyanions are not required to maintain the infectious properties of hamster prions. Here, we review these results and discuss the potential roles cofactors might play in encoding prion infectivity and/or strain properties.
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Affiliation(s)
- Justin R Piro
- Departments of Biochemistry, Dartmouth Medical School, Hanover, NH, USA
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457
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Bate C, Williams A. The cellular prion protein with a monoacylated glycosylphosphatidylinositol anchor modifies cell membranes, inhibits cell signaling and reduces prion formation. Prion 2011; 5:65-8. [PMID: 21738009 DOI: 10.4161/pri.5.2.16095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The prion diseases occur following the conversion of the cellular prion protein (PrPC) into a disease-related isoform (PrPSc). In this study a cell painting technique was used to examine the role of the glycosylphosphatidylinositol (GPI) anchor attached to PrPC in prion formation. The introduction of PrPC to infected neuronal cells increased the cholesterol content of cell membranes, increased activation of cytoplasmic phospholipase A2 (cPLA2) and increased PrPSc formation. In contrast, PrPC with a monoacylated GPI anchor did not alter the amount of cholesterol in cell membranes, was not found within lipid rafts and did not activate cPLA2. Although monoacylated PrPC remains within cells for longer than native PrPC it was not converted to PrPSc. Moreover, the presence of monoacylated PrPC displaced cPLA2 from PrPSc-containing lipid rafts, reducing the activation of cPLA2 and PrPSc formation. We conclude that acylation of the GPI anchor attached to PrPC modifies the local membrane microenvironments that control some cell signaling pathways, the trafficking of PrPC and PrPSc formation. In addition, such observations raise the possibility that the pharmacological modification of GPI anchors might constitute a novel therapeutic approach to prion diseases.
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Affiliation(s)
- Clive Bate
- Department of Pathology and Infectious Diseases, Royal Veterinary College, North Mymms, Herts, UK. on protein (PrP
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458
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Prigent S, Rezaei H. PrP assemblies: spotting the responsible regions in prion propagation. Prion 2011; 5:69-75. [PMID: 21788728 DOI: 10.4161/pri.5.2.16383] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The "protein only" hypothesis states that the key phenomenon in prion pathogenesis is the conversion of the host protein (PrPC) into a b-sheet enriched polymeric and pathogenic conformer (PrPSc). However the region of PrP bearing the information for structural transfer is still controversial. In a recent report, we highlighted the role of the C terminal part i.e. the helixes H2 and H3, using mutation approaches on recombinant PrP. The H2H3 was shown to be the minimal region necessary to reproduce the oligomerisation pattern of the full-length protein. The oligomers produced from isolated H2H3 domain presented the same structural characteristics as the oligomers formed from the full-length PrP. Combining other groups' results, this paper further discusses the relative, direct or indirect role of different PrP regions in assembly. The H2H3 region represents the core of PrP oligomers and fibrils, whereas the N terminus could explain divergences among different aggregates. Finally this review evocates the possibility to separate the domain involved in prion information transference (i.e. prion replication) from the domain bearing the cytotoxicity properties.
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459
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DiSalvo S, Serio TR. Insights into prion biology: integrating a protein misfolding pathway with its cellular environment. Prion 2011; 5:76-83. [PMID: 21654204 DOI: 10.4161/pri.5.2.16413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Protein misfolding and assembly into ordered, self-templating aggregates (amyloid) has emerged as a novel mechanism for regulating protein function. For a subclass of amyloidogenic proteins known as prions, this process induces transmissible changes in normal cellular physiology, ranging from neurodegenerative disease in animals and humans to new traits in fungi. The severity and stability of these altered phenotypic states can be attenuated by the conformation or amino-acid sequence of the prion, but in most of these cases, the protein retains the ability to form amyloid in vitro. Thus, our ability to link amyloid formation in vitro with its biological consequences in vivo remains a challenge. In two recent studies, we have begun to address this disconnect by assessing the effects of the cellular environment on traits associated with the misfolding of the yeast prion Sup35. Remarkably, the effects of quality control pathways and of limitations on protein transfer in vivo amplify the effects of even slight differences in the efficiency of Sup35 misfolding, leading to dramatic changes in the associated phenotype. Together, our studies suggest that the interplay between protein misfolding pathways and their cellular context is a crucial contributor to prion biology.
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Affiliation(s)
- Susanne DiSalvo
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA
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460
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Human PrP90-231-induced cell death is associated with intracellular accumulation of insoluble and protease-resistant macroaggregates and lysosomal dysfunction. Cell Death Dis 2011; 2:e138. [PMID: 21451573 PMCID: PMC3101817 DOI: 10.1038/cddis.2011.21] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To define the mechanisms by which hPrP90-231 induces cell death, we analyzed its interaction with living cells and monitored its intracellular fate. Treatment of SH-SY5Y cells with fluorescein-5-isothiocyanate (FITC)-conjugated hPrP90-231 caused the accumulation of cytosolic aggregates of the prion protein fragment that increased in number and size in a time-dependent manner. The formation of large intracellular hPrP90-231 aggregates correlated with the activation of apoptosis. hPrP90-231 aggregates occurred within lysotracker-positive vesicles and induced the formation of activated cathepsin D (CD), indicating that hPrP90-231 is partitioned into the endosomal-lysosomal system structures, activating the proteolytic machinery. Remarkably, the inhibition of CD activity significantly reduced hPrP-90-231-dependent apoptosis. Internalized hPrP90-231 forms detergent-insoluble and SDS-stable aggregates, displaying partial resistance to proteolysis. By confocal microscopy analysis of lucifer yellow (LY) intracellular partition, we show that hPrP90-231 accumulation induces lysosome destabilization and loss of lysosomal membrane impermeability. In fact, although control cells evidenced a vesicular pattern of LY fluorescence (index of healthy lysosomes), hPrP90-231-treated cells showed diffuse cytosolic fluorescence, indicating LY diffusion through damaged lysosomes. In conclusion, these data indicate that exogenously added hPrP90-231 forms intralysosomal deposits having features of insoluble, protease-resistant aggregates and could trigger a lysosome-mediated apoptosis by inducing lysosome membrane permeabilization, followed by the release of hydrolytic enzymes.
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461
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In vitro amplification of misfolded prion protein using lysate of cultured cells. PLoS One 2011; 6:e18047. [PMID: 21464935 PMCID: PMC3065467 DOI: 10.1371/journal.pone.0018047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 02/18/2011] [Indexed: 11/19/2022] Open
Abstract
Protein misfolding cyclic amplification (PMCA) recapitulates the prion protein (PrP) conversion process under cell-free conditions. PMCA was initially established with brain material and then with further simplified constituents such as partially purified and recombinant PrP. However, availability of brain material from some species or brain material from animals with certain mutations or polymorphisms within the PrP gene is often limited. Moreover, preparation of native PrP from mammalian cells and tissues, as well as recombinant PrP from bacterial cells, involves time-consuming purification steps. To establish a convenient and versatile PMCA procedure unrestricted to the availability of substrate sources, we attempted to conduct PMCA with the lysate of cells that express cellular PrP (PrPC). PrPSc was efficiently amplified with lysate of rabbit kidney epithelial RK13 cells stably transfected with the mouse or Syrian hamster PrP gene. Furthermore, PMCA was also successful with lysate of other established cell lines of neuronal or non-neuronal origins. Together with the data showing that the abundance of PrPC in cell lysate was a critical factor to drive efficient PrPSc amplification, our results demonstrate that cell lysate in which PrPC is present abundantly serves as an excellent substrate source for PMCA.
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462
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Smirnovas V, Baron GS, Offerdahl DK, Raymond GJ, Caughey B, Surewicz WK. Structural organization of brain-derived mammalian prions examined by hydrogen-deuterium exchange. Nat Struct Mol Biol 2011; 18:504-6. [PMID: 21441913 PMCID: PMC3379881 DOI: 10.1038/nsmb.2035] [Citation(s) in RCA: 186] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 01/20/2011] [Indexed: 12/18/2022]
Abstract
One of the mysteries in prion research is the structure of the infectious form of mammalian prion protein, PrPSc. We used MS analysis of H/D exchange to examine brain-derived PrPSc. Our data indicate that, contrary to popular models, prion protein conversion involves refolding of the entire region C-terminal to residue ~80–90, and that this region in PrPSc consists of ß-strands and relatively short turns/loops, with no native α-helices present.
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Affiliation(s)
- Vytautas Smirnovas
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, USA
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463
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Abstract
Prion sorption to soil is thought to play an important role in the transmission of scrapie and chronic wasting disease (CWD) via the environment. Sorption of PrP to soil and soil minerals is influenced by the strain and species of PrP(Sc) and by soil characteristics. However, the ability of soil-bound prions to convert PrP(c) to PrP(Sc) under these wide-ranging conditions remains poorly understood. We developed a semiquantitative protein misfolding cyclic amplification (PMCA) protocol to evaluate replication efficiency of soil-bound prions. Binding of the hyper (HY) strain of transmissible mink encephalopathy (TME) (hamster) prions to a silty clay loam soil yielded a greater-than-1-log decrease in PMCA replication efficiency with a corresponding 1.3-log reduction in titer. The increased binding of PrP(Sc) to soil over time corresponded with a decrease in PMCA replication efficiency. The PMCA efficiency of bound prions varied with soil type, where prions bound to clay and organic surfaces exhibited significantly lower replication efficiencies while prions bound to sand exhibited no apparent difference in replication efficiency compared to unbound controls. PMCA results from hamster and CWD agent-infected elk prions yielded similar findings. Given that PrP(Sc) adsorption affinity varies with soil type, the overall balance between prion adsorption affinity and replication efficiency for the dominant soil types of an area may be a significant determinant in the environmental transmission of prion diseases.
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464
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Ayers JI, Schutt CR, Shikiya RA, Aguzzi A, Kincaid AE, Bartz JC. The strain-encoded relationship between PrP replication, stability and processing in neurons is predictive of the incubation period of disease. PLoS Pathog 2011; 7:e1001317. [PMID: 21437239 PMCID: PMC3060105 DOI: 10.1371/journal.ppat.1001317] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 02/10/2011] [Indexed: 02/07/2023] Open
Abstract
Prion strains are characterized by differences in the outcome of disease, most notably incubation period and neuropathological features. While it is established that the disease specific isoform of the prion protein, PrPSc, is an essential component of the infectious agent, the strain-specific relationship between PrPSc properties and the biological features of the resulting disease is not clear. To investigate this relationship, we examined the amplification efficiency and conformational stability of PrPSc from eight hamster-adapted prion strains and compared it to the resulting incubation period of disease and processing of PrPSc in neurons and glia. We found that short incubation period strains were characterized by more efficient PrPSc amplification and higher PrPSc conformational stabilities compared to long incubation period strains. In the CNS, the short incubation period strains were characterized by the accumulation of N-terminally truncated PrPSc in the soma of neurons, astrocytes and microglia in contrast to long incubation period strains where PrPSc did not accumulate to detectable levels in the soma of neurons but was detected in glia similar to short incubation period strains. These results are inconsistent with the hypothesis that a decrease in conformational stability results in a corresponding increase in replication efficiency and suggest that glia mediated neurodegeneration results in longer survival times compared to direct replication of PrPSc in neurons. Prion diseases are a group of infectious fatal neurodegenerative diseases that affect animals including humans. This unique infectious agent is the result of a post-translational conformational change of the normal form of the prion protein, PrPC, to an infectious form of the prion protein, PrPSc. Different strains of the infectious agent result in characteristic incubation periods and neuropathological features within a single host species. These strain-specific differences in disease outcome are likely due to strain-specific conformations of PrPSc, though the mechanisms by which different conformation can affect prion strain properties are not understood. The aim of this study was to investigate the relationship between the biochemical properties of PrPSc to the corresponding neuropathological characteristics of eight hamster-adapted prion strains. Our findings indicate that PrPSc from short incubation period strains were more efficiently replicated, had a more stable conformation, and were observed to be more resistant to clearance from the soma of neurons compared to prion strains with a relatively long incubation period. These results suggest the progression of prion disease is influenced by the balance between replication and clearance of PrPSc in neurons.
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Affiliation(s)
- Jacob I. Ayers
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Charles R. Schutt
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Ronald A. Shikiya
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
| | - Adriano Aguzzi
- Institute of Neuropathology, University Hospital Zurich, Zurich, Switzerland
| | - Anthony E. Kincaid
- Department of Physical Therapy, Creighton University, Omaha, Nebraska, United States of America
| | - Jason C. Bartz
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska, United States of America
- * E-mail:
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465
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Wadsworth JDF, Asante EA, Collinge J. Review: contribution of transgenic models to understanding human prion disease. Neuropathol Appl Neurobiol 2011; 36:576-97. [PMID: 20880036 PMCID: PMC3017745 DOI: 10.1111/j.1365-2990.2010.01129.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Transgenic mice expressing human prion protein in the absence of endogenous mouse prion protein faithfully replicate human prions. These models reproduce all of the key features of human disease, including long clinically silent incubation periods prior to fatal neurodegeneration with neuropathological phenotypes that mirror human prion strain diversity. Critical contributions to our understanding of human prion disease pathogenesis and aetiology have only been possible through the use of transgenic mice. These models have provided the basis for the conformational selection model of prion transmission barriers and have causally linked bovine spongiform encephalopathy with variant Creutzfeldt-Jakob disease. In the future these models will be essential for evaluating newly identified potentially zoonotic prion strains, for validating effective methods of prion decontamination and for developing effective therapeutic treatments for human prion disease.
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Affiliation(s)
- J D F Wadsworth
- MRC Prion Unit and Department of Neurodegenerative Disease, Institute of Neurology, University College London, National Hospital for Neurology and Neurosurgery, London, UK.
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466
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Wisniewski T, Goñi F. Immunomodulation for prion and prion-related diseases. Expert Rev Vaccines 2011; 9:1441-52. [PMID: 21105779 DOI: 10.1586/erv.10.131] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Prion diseases are a unique category of illness, affecting both animals and humans, where the underlying pathogenesis is related to a conformational change of a normal self protein called cellular prion protein to a pathological and infectious conformer known as scrapie prion protein (PrP(Sc)). Currently, all prion diseases lack effective treatment and are universally fatal. Past experiences with bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease mainly in Europe, as well as the current epidemic of chronic wasting disease in North America, have highlighted the need to develop prophylactic and/or therapeutic approaches. In Alzheimer's disease that, like prion disease, is a conformational neurodegenerative disorder, both passive and active immunization has been shown to be highly effective in model animals at preventing disease and cognitive deficits, with emerging data from human trials suggesting that this approach is able to reduce amyloid-related pathology. However, any immunomodulatory approach aimed at a self-antigen has to finely balance an effective humoral immune response with potential autoimmune toxicity. The prion diseases most commonly acquired by infection typically have the alimentary tract as a portal of infectious agent entry. This makes mucosal immunization a potentially attractive method to produce a local immune response that partially or completely prevents prion entry across the gut barrier, while at the same time producing modulated systemic immunity that is unlikely to be associated with toxicity. Our results using an attenuated Salmonella vaccine strain expressing the prion protein showed that mucosal vaccination can protect against prion infection from a peripheral source, suggesting the feasibility of this approach. It is also possible to develop active and/or passive immunomodulatory approaches that more specifically target PrP(Sc) or target the shared pathological conformer found in numerous conformational disorders. Such approaches could have a significant impact on many of the common age-associated dementias.
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Affiliation(s)
- Thomas Wisniewski
- Department of Psychiatry, Millhauser Laboratories, Room HN419, New York University School of Medicine, 560 First Avenue, New York, NY 10016, USA.
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467
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Greenwald J, Riek R. Biology of amyloid: structure, function, and regulation. Structure 2011; 18:1244-60. [PMID: 20947013 DOI: 10.1016/j.str.2010.08.009] [Citation(s) in RCA: 427] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 08/18/2010] [Accepted: 08/30/2010] [Indexed: 01/23/2023]
Abstract
Amyloids are highly ordered cross-β sheet protein aggregates associated with many diseases including Alzheimer's disease, but also with biological functions such as hormone storage. The cross-β sheet entity comprising an indefinitely repeating intermolecular β sheet motif is unique among protein folds. It grows by recruitment of the corresponding amyloid protein, while its repetitiveness can translate what would be a nonspecific activity as monomer into a potent one through cooperativity. Furthermore, the one-dimensional crystal-like repeat in the amyloid provides a structural framework for polymorphisms. This review summarizes the recent high-resolution structural studies of amyloid fibrils in light of their biological activities. We discuss how the unique properties of amyloids gives rise to many activities and further speculate about currently undocumented biological roles for the amyloid entity. In particular, we propose that amyloids could have existed in a prebiotic world, and may have been the first functional protein fold in living cells.
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Affiliation(s)
- Jason Greenwald
- ETH Zurich, Physical Chemistry, ETH Honggerberg, 8093 Zurich, Switzerland
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468
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Gonzalez Nelson AC, Ross ED. Interactions between non-identical prion proteins. Semin Cell Dev Biol 2011; 22:437-43. [PMID: 21354317 DOI: 10.1016/j.semcdb.2011.02.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 02/16/2011] [Accepted: 02/17/2011] [Indexed: 11/24/2022]
Abstract
Prion formation involves the conversion of soluble proteins into an infectious amyloid form. This process is highly specific, with prion aggregates templating the conversion of identical proteins. However, in some cases non-identical prion proteins can interact to promote or inhibit prion formation or propagation. These interactions affect both the efficiency with which prion diseases are transmitted across species and the normal physiology of yeast prion formation and propagation. Here we examine two types of heterologous prion interactions: interactions between related proteins from different species (the species barrier) and interactions between unrelated prion proteins within a single species. Interestingly, although very subtle changes in protein sequence can significantly reduce or eliminate cross-species prion transmission, in Saccharomyces cerevisiae completely unrelated prion proteins can interact to affect prion formation and propagation.
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Affiliation(s)
- Aaron C Gonzalez Nelson
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
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469
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Wickner RB, Shewmaker F, Edskes H, Kryndushkin D, Nemecek J, McGlinchey R, Bateman D, Winchester CL. Prion amyloid structure explains templating: how proteins can be genes. FEMS Yeast Res 2011; 10:980-91. [PMID: 20726897 DOI: 10.1111/j.1567-1364.2010.00666.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The yeast and fungal prions determine heritable and infectious traits, and are thus genes composed of protein. Most prions are inactive forms of a normal protein as it forms a self-propagating filamentous β-sheet-rich polymer structure called amyloid. Remarkably, a single prion protein sequence can form two or more faithfully inherited prion variants, in effect alleles of these genes. What protein structure explains this protein-based inheritance? Using solid-state nuclear magnetic resonance, we showed that the infectious amyloids of the prion domains of Ure2p, Sup35p and Rnq1p have an in-register parallel architecture. This structure explains how the amyloid filament ends can template the structure of a new protein as it joins the filament. The yeast prions [PSI(+)] and [URE3] are not found in wild strains, indicating that they are a disadvantage to the cell. Moreover, the prion domains of Ure2p and Sup35p have functions unrelated to prion formation, indicating that these domains are not present for the purpose of forming prions. Indeed, prion-forming ability is not conserved, even within Saccharomyces cerevisiae, suggesting that the rare formation of prions is a disease. The prion domain sequences generally vary more rapidly in evolution than does the remainder of the molecule, producing a barrier to prion transmission, perhaps selected in evolution by this protection.
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Affiliation(s)
- Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
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470
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Wemheuer WM, Benestad SL, Wrede A, Wemheuer WE, Brenig B, Bratberg B, Schulz-Schaeffer WJ. PrPSc spreading patterns in the brain of sheep linked to different prion types. Vet Res 2011; 42:32. [PMID: 21324114 PMCID: PMC3050706 DOI: 10.1186/1297-9716-42-32] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 02/15/2011] [Indexed: 11/17/2022] Open
Abstract
Scrapie in sheep and goats has been known for more than 250 years and belongs nowadays to the so-called prion diseases that also include e.g. bovine spongiform encephalopathy in cattle (BSE) and Creutzfeldt-Jakob disease in humans. According to the prion hypothesis, the pathological isoform (PrPSc) of the cellular prion protein (PrPc) comprises the essential, if not exclusive, component of the transmissible agent. Currently, two types of scrapie disease are known - classical and atypical/Nor98 scrapie. In the present study we examine 24 cases of classical and 25 cases of atypical/Nor98 scrapie with the sensitive PET blot method and validate the results with conventional immunohistochemistry. The sequential detection of PrPSc aggregates in the CNS of classical scrapie sheep implies that after neuroinvasion a spread from spinal cord and obex to the cerebellum, diencephalon and frontal cortex via the rostral brainstem takes place. We categorize the spread of PrPSc into four stages: the CNS entry stage, the brainstem stage, the cruciate sulcus stage and finally the basal ganglia stage. Such a sequential development of PrPSc was not detectable upon analysis of the present atypical/Nor98 scrapie cases. PrPSc distribution in one case of atypical/Nor98 scrapie in a presumably early disease phase suggests that the spread of PrPSc aggregates starts in the di- or telencephalon. In addition to the spontaneous generation of PrPSc, an uptake of the infectious agent into the brain, that bypasses the brainstem and starts its accumulation in the thalamus, needs to be taken into consideration for atypical/Nor98 scrapie.
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Affiliation(s)
- Wiebke M Wemheuer
- Prion and Dementia Research Unit, Department of Neuropathology, University Medical Center, Georg-August University, Robert-Koch Str, 40, 37075 Goettingen, Germany.
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471
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Hafner-Bratkovic I, Bester R, Pristovsek P, Gaedtke L, Veranic P, Gaspersic J, Mancek-Keber M, Avbelj M, Polymenidou M, Julius C, Aguzzi A, Vorberg I, Jerala R. Globular domain of the prion protein needs to be unlocked by domain swapping to support prion protein conversion. J Biol Chem 2011; 286:12149-56. [PMID: 21324909 DOI: 10.1074/jbc.m110.213926] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Prion diseases are fatal transmissible neurodegenerative diseases affecting many mammalian species. The normal prion protein (PrP) converts into a pathological aggregated form, PrPSc, which is enriched in the β-sheet structure. Although the high resolution structure of the normal PrP was determined, the structure of the converted form of PrP remains inaccessible to high resolution techniques. To map the PrP conversion process we introduced disulfide bridges into different positions within the globular domain of PrP, tethering selected secondary structure elements. The majority of tethered PrP mutants exhibited increased thermodynamic stability, nevertheless, they converted efficiently. Only the disulfides that tether subdomain B1-H1-B2 to subdomain H2-H3 prevented PrP conversion in vitro and in prion-infected cell cultures. Reduction of disulfides recovered the ability of these mutants to convert, demonstrating that the separation of subdomains is an essential step in conversion. Formation of disulfide-linked proteinase K-resistant dimers in fibrils composed of a pair of single cysteine mutants supports the model based on domain-swapped dimers as the building blocks of prion fibrils. In contrast to previously proposed structural models of PrPSc suggesting conversion of large secondary structural segments, we provide evidence for the conservation of secondary structural elements of the globular domain upon PrP conversion. Previous studies already showed that dimerization is the rate-limiting step in PrP conversion. We show that separation and swapping of subdomains of the globular domain is necessary for conversion. Therefore, we propose that the domain-swapped dimer of PrP precedes amyloid formation and represents a potential target for therapeutic intervention.
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Affiliation(s)
- Iva Hafner-Bratkovic
- Department of Biotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
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472
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Highly efficient protein misfolding cyclic amplification. PLoS Pathog 2011; 7:e1001277. [PMID: 21347353 PMCID: PMC3037363 DOI: 10.1371/journal.ppat.1001277] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 01/07/2011] [Indexed: 01/13/2023] Open
Abstract
Protein misfolding cyclic amplification (PMCA) provides faithful replication of mammalian prions in vitro and has numerous applications in prion research. However, the low efficiency of conversion of PrP(C) into PrP(Sc) in PMCA limits the applicability of PMCA for many uses including structural studies of infectious prions. It also implies that only a small sub-fraction of PrP(C) may be available for conversion. Here we show that the yield, rate, and robustness of prion conversion and the sensitivity of prion detection are significantly improved by a simple modification of the PMCA format. Conducting PMCA reactions in the presence of Teflon beads (PMCAb) increased the conversion of PrP(C) into PrP(Sc) from ∼10% to up to 100%. In PMCAb, a single 24-hour round consistently amplified PrP(Sc) by 600-700-fold. Furthermore, the sensitivity of prion detection in one round (24 hours) increased by 2-3 orders of magnitude. Using serial PMCAb, a 10¹²-fold dilution of scrapie brain material could be amplified to the level detectible by Western blotting in 3 rounds (72 hours). The improvements in amplification efficiency were observed for the commonly used hamster 263K strain and for the synthetic strain SSLOW that otherwise amplifies poorly in PMCA. The increase in the amplification efficiency did not come at the expense of prion replication specificity. The current study demonstrates that poor conversion efficiencies observed previously have not been due to the scarcity of a sub-fraction of PrP(C) susceptible to conversion nor due to limited concentrations of essential cellular cofactors required for conversion. The new PMCAb format offers immediate practical benefits and opens new avenues for developing fast ultrasensitive assays and for producing abundant quantities of PrP(Sc)in vitro.
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473
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Piro JR, Harris BT, Supattapone S. In situ photodegradation of incorporated polyanion does not alter prion infectivity. PLoS Pathog 2011; 7:e1002001. [PMID: 21304885 PMCID: PMC3033378 DOI: 10.1371/journal.ppat.1002001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 12/13/2010] [Indexed: 01/03/2023] Open
Abstract
Single-stranded polyanions ≥40 bases in length facilitate the formation of hamster scrapie prions in vitro, and polyanions co-localize with PrPSc aggregates in vivo[1], [2]. To test the hypothesis that intact polyanionic molecules might serve as a structural backbone essential for maintaining the infectious conformation(s) of PrPSc, we produced synthetic prions using a photocleavable, 100-base oligonucleotide (PC-oligo). In serial Protein Misfolding Cyclic Amplification (sPMCA) reactions using purified PrPC substrate, PC-oligo was incorporated into physical complexes with PrPSc molecules that were resistant to benzonase digestion. Exposure of these nuclease-resistant prion complexes to long wave ultraviolet light (315 nm) induced degradation of PC-oligo into 5 base fragments. Light-induced photolysis of incorporated PC-oligo did not alter the infectivity of in vitro-generated prions, as determined by bioassay in hamsters and brain homogenate sPMCA assays. Neuropathological analysis also revealed no significant differences in the neurotropism of prions containing intact versus degraded PC-oligo. These results show that polyanions >5 bases in length are not required for maintaining the infectious properties of in vitro-generated scrapie prions, and indicate that such properties are maintained either by short polyanion remnants, other co-purified cofactors, or by PrPSc molecules alone. Prions are unorthodox infectious agents whose composition remains undetermined. Previous experiments have shown that long, negatively charged polymers such as nucleic acid and carbohydrate molecules promote the formation of purified prions in test tube chemical reactions. Various classes of negatively charged polymers have also been found to co-exist within prion complexes in the brains of infected animals. These observations suggest that negatively charged polymers might act as a structural support necessary for prion infectivity. We tested this possibility by chemically synthesizing a negatively charged polymer that can be degraded by exposure to ultraviolet light. Prions containing this light-sensitive polymer remained infectious after light exposure, indicating that negatively charged polymers are not necessary to maintain the structural shapes of infectious prions.
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Affiliation(s)
- Justin R. Piro
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Brent T. Harris
- Department of Pathology, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Surachai Supattapone
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire, United States of America
- Department of Medicine, Dartmouth Medical School, Hanover, New Hampshire, United States of America
- * E-mail:
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474
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475
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Bjorndahl TC, Zhou GP, Liu X, Perez-Pineiro R, Semenchenko V, Saleem F, Acharya S, Bujold A, Sobsey CA, Wishart DS. Detailed biophysical characterization of the acid-induced PrP(c) to PrP(β) conversion process. Biochemistry 2011; 50:1162-73. [PMID: 21189021 DOI: 10.1021/bi101435c] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Prions are believed to spontaneously convert from a native, monomeric highly helical form (called PrP(c)) to a largely β-sheet-rich, multimeric and insoluble aggregate (called PrP(sc)). Because of its large size and insolubility, biophysical characterization of PrP(sc) has been difficult, and there are several contradictory or incomplete models of the PrP(sc) structure. A β-sheet-rich, soluble intermediate, called PrP(β), exhibits many of the same features as PrP(sc) and can be generated using a combination of low pH and/or mild denaturing conditions. Studies of the PrP(c) to PrP(β) conversion process and of PrP(β) folding intermediates may provide insights into the structure of PrP(sc). Using a truncated, recombinant version of Syrian hamster PrP(β) (shPrP(90-232)), we used NMR spectroscopy, in combination with other biophysical techniques (circular dichroism, dynamic light scattering, electron microscopy, fluorescence spectroscopy, mass spectrometry, and proteinase K digestion), to characterize the pH-driven PrP(c) to PrP(β) conversion process in detail. Our results show that below pH 2.8 the protein oligomerizes and conversion to the β-rich structure is initiated. At pH 1.7 and above, the oligomeric protein can recover its native monomeric state through dialysis to pH 5.2. However, when conversion is completed at pH 1.0, the large oligomer "locks down" irreversibly into a stable, β-rich form. At pH values above 3.0, the protein is amenable to NMR investigation. Chemical shift perturbations, NOE, amide line width, and T(2) measurements implicate the putative "amylome motif" region, "NNQNNF" as the region most involved in the initial helix-to-β conversion phase. We also found that acid-induced PrP(β) oligomers could be converted to fibrils without the use of chaotropic denaturants. The latter finding represents one of the first examples wherein physiologically accessible conditions (i.e., only low pH) were used to achieve PrP conversion and fibril formation.
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Affiliation(s)
- Trent C Bjorndahl
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E8
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476
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Thackray AM, Hopkins L, Lockey R, Spiropoulos J, Bujdoso R. Emergence of multiple prion strains from single isolates of ovine scrapie. J Gen Virol 2011; 92:1482-1491. [PMID: 21270287 DOI: 10.1099/vir.0.028886-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The infectious agent associated with prion diseases such as ovine scrapie shows strain diversity. Ovine prion strains have typically been identified by their transmission properties in wild-type mice. However, strain typing of ovine scrapie isolates in wild-type mice may not reveal properties of the infectious prion agent as they exist in the original host. This could be circumvented if ovine scrapie isolates are passaged in ovine prion protein (PrP)-transgenic mice. This study used incubation time, lesion profile, immunohistochemistry of the disease-associated PrP (PrP(Sc)) and molecular profile to compare the range of ovine prion strains that emerged from sheep scrapie isolates following serial passage in wild-type and ovine PrP transgenic mice. It was found that a diverse range of ovine prion strains emerged from homozygous ARQ and VRQ scrapie isolates passaged in wild-type and ovine PrP transgenic mice. However, strain-specific PrP(Sc) deposition and PrP27-30 molecular profile patterns were identified in ovine PrP transgenic mice that were not detected in wild-type mice. Significantly, it was established that the individual mouse brain selected for transmission during prion strain typing had a significant influence on strain definition. Serial passage of short- and long-incubation-time animals from the same group of scrapie-inoculated mice revealed different prion strain phenotypes. These observations are consistent with the possibility that some scrapie isolates contain more than one prion strain.
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Affiliation(s)
- Alana M Thackray
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge CB3 0ES, UK
| | - Lee Hopkins
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge CB3 0ES, UK
| | - Richard Lockey
- Veterinary Laboratories Agency, Department of Pathology and Host Susceptibility, Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - John Spiropoulos
- Veterinary Laboratories Agency, Department of Pathology and Host Susceptibility, Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Raymond Bujdoso
- University of Cambridge, Department of Veterinary Medicine, Madingley Road, Cambridge CB3 0ES, UK
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477
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Jain S, Udgaonkar JB. Defining the Pathway of Worm-like Amyloid Fibril Formation by the Mouse Prion Protein by Delineation of the Productive and Unproductive Oligomerization Reactions. Biochemistry 2011; 50:1153-61. [DOI: 10.1021/bi101757x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Shweta Jain
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Jayant B. Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
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478
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Protein-only mechanism induces self-perpetuating changes in the activity of neuronal Aplysia cytoplasmic polyadenylation element binding protein (CPEB). Proc Natl Acad Sci U S A 2011; 108:2999-3004. [PMID: 21270333 DOI: 10.1073/pnas.1019368108] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuronal cytoplasmic polyadenylation element binding protein (CPEB) plays a critical role in maintaining the functional and morphological long-lasting synaptic changes that underlie learning and memory. It can undergo a prion switch, but it remains unclear if this self-templating change in protein conformation is alone sufficient to create a stable change in CPEB activity: a robust "protein-only" biochemical memory. To investigate, we take advantage of yeast cells wherein the neuronal CPEB of Aplysia is expressed in the absence of any neuronal factors and can stably adopt either an active or an inactive state. Reminiscent of well-characterized yeast prions, we find that CPEB can adopt several distinct activity states or "strains." These states are acquired at a much higher spontaneous rate than is typical of yeast prions, but they are extremely stable--perpetuating for years--and have all of the non-Mendelian genetic characteristics of bona fide yeast prions. CPEB levels are too low to allow direct physical characterization, but CPEB strains convert a fusion protein, which shares only the prion-like domain of CPEB, into amyloid in a strain-specific manner. Lysates of CPEB strains seed the purified prion domain to adopt the amyloid conformation with strain-specific efficiencies. Amyloid conformers generated by spontaneous assembly of the purified prion domain (and a more biochemically tractable derivative) transformed cells with inactive CPEB into the full range of distinct CPEB strains. Thus, CPEB employs a prion mechanism to create stable, finely tuned self-perpetuating biochemical memories. These biochemical memories might be used in the local homeostatic maintenance of long-term learning-related changes in synaptic morphology and function.
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479
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Joint Scientific Opinion on any possible epidemiological or molecular association between TSEs in animals and humans. EFSA J 2011. [DOI: 10.2903/j.efsa.2011.1945] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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480
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Glycosylphosphatidylinositol anchor-dependent stimulation pathway required for generation of baculovirus-derived recombinant scrapie prion protein. J Virol 2011; 85:2582-8. [PMID: 21228241 DOI: 10.1128/jvi.02098-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The pathogenic isoform (PrP(Sc)) of the host-encoded cellular prion protein (PrP(C)) is considered to be an infectious agent of transmissible spongiform encephalopathy (TSE). The detailed mechanism by which the PrP(Sc) seed catalyzes the structural conversion of endogenous PrP(C) into nascent PrP(Sc) in vivo still remains unclear. Recent studies reveal that bacterially derived recombinant PrP (recPrP) can be used as a substrate for the in vitro generation of protease-resistant recPrP (recPrP(res)) by protein-misfolding cyclic amplification (PMCA). These findings imply that PrP modifications with a glycosylphosphatidylinositol (GPI) anchor and asparagine (N)-linked glycosylation are not necessary for the amplification and generation of recPrP(Sc) by PMCA. However, the biological properties of PrP(Sc) obtained by in vivo transmission of recPrP(res) are unique or different from those of PrP(Sc) used as the seed, indicating that the mechanisms mediated by these posttranslational modifications possibly participate in reproductive propagation of PrP(Sc). In the present study, using baculovirus-derived recombinant PrP (Bac-PrP), we demonstrated that Bac-PrP is useful as a PrP(C) substrate for amplification of the mouse scrapie prion strain Chandler, and PrP(Sc) that accumulated in mice inoculated with Bac-PrP(res) had biochemical and pathological properties very similar to those of the PrP(Sc) seed. Since Bac-PrP modified with a GPI anchor and brain homogenate of Prnp knockout mice were both required to generate Bac-PrP(res), the interaction of GPI-anchored PrP with factors in brain homogenates is essential for reproductive propagation of PrP(Sc). Therefore, the Bac-PMCA technique appears to be extremely beneficial for the comprehensive understanding of the GPI anchor-mediated stimulation pathway.
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481
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Bate C, Williams A. Monoacylated cellular prion protein modifies cell membranes, inhibits cell signaling, and reduces prion formation. J Biol Chem 2011; 286:8752-8. [PMID: 21212283 DOI: 10.1074/jbc.m110.186833] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Prion diseases occur following the conversion of the cellular prion protein (PrP(C)) into a disease related, protease-resistant isoform (PrP(Sc)). In these studies, a cell painting technique was used to introduce PrP(C) to prion-infected neuronal cell lines (ScGT1, ScN2a, or SMB cells). The addition of PrP(C) resulted in increased PrP(Sc) formation that was preceded by an increase in the cholesterol content of cell membranes and increased activation of cytoplasmic phospholipase A(2) (cPLA(2)). In contrast, although PrP(C) lacking one of the two acyl chains from its glycosylphosphatidylinositol (GPI) anchor (PrP(C)-G-lyso-PI) bound readily to cells, it did not alter the amount of cholesterol in cell membranes, was not found within detergent-resistant membranes (lipid rafts), and did not activate cPLA(2). It remained within cells for longer than PrP(C) with a conventional GPI anchor and was not converted to PrP(Sc). Moreover, the addition of high amounts of PrP(C)-G-lyso-PI displaced cPLA(2) from PrP(Sc)-containing lipid rafts, reduced the activation of cPLA(2), and reduced PrP(Sc) formation in all three cell lines. In addition, ScGT1 cells treated with PrP(C)-G-lyso-PI did not transmit infection following intracerebral injection to mice. We propose that that the chemical composition of the GPI anchor attached to PrP(C) modified the local membrane microenvironments that control cell signaling, the fate of PrP(C), and hence PrP(Sc) formation. In addition, our observations raise the possibility that pharmacological modification of GPI anchors might constitute a novel therapeutic approach to prion diseases.
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Affiliation(s)
- Clive Bate
- Department of Pathology and Infectious Diseases, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire AL9 7TA, United Kingdom.
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482
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Gambetti P, Cali I, Notari S, Kong Q, Zou WQ, Surewicz WK. Molecular biology and pathology of prion strains in sporadic human prion diseases. Acta Neuropathol 2011; 121:79-90. [PMID: 21058033 PMCID: PMC3077936 DOI: 10.1007/s00401-010-0761-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 09/28/2010] [Accepted: 10/11/2010] [Indexed: 01/12/2023]
Abstract
Prion diseases are believed to propagate by the mechanism involving self-perpetuating conformational conversion of the normal form of the prion protein, PrP(C), to the misfolded, pathogenic state, PrP(Sc). One of the most intriguing aspects of these disorders is the phenomenon of prion strains. It is believed that strain properties are fully encoded in distinct conformations of PrP(Sc). Strains are of practical relevance to human prion diseases as their diversity may explain the unusual heterogeneity of these disorders. The first insight into the molecular mechanisms underlying heterogeneity of human prion diseases was provided by the observation that two distinct disease phenotypes and their associated PrP(Sc) conformers co-distribute with distinct PrP genotypes as determined by the methionine/valine polymorphism at codon 129 of the PrP gene. Subsequent studies identified six possible combinations of the three genotypes (determined by the polymorphic codon 129) and two common PrP(Sc) conformers (named types 1 and 2) as the major determinants of the phenotype in sporadic human prion diseases. This scenario implies that each 129 genotype-PrP(Sc) type combination would be associated with a distinct disease phenotype and prion strain. However, notable exceptions have been found. For example, two genotype-PrP(Sc) type combinations are linked to the same phenotype, and conversely, the same combination was found to be associated with two distinct phenotypes. Furthermore, in some cases, PrP(Sc) conformers naturally associated with distinct phenotypes appear, upon transmission, to lose their phenotype-determining strain characteristics. Currently it seems safe to assume that typical sporadic prion diseases are associated with at least six distinct prion strains. However, the intrinsic characteristics that distinguish at least four of these strains remain to be identified.
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Affiliation(s)
- Pierluigi Gambetti
- Department of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, OH, 44106, USA.
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483
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Jones M, Peden AH, Head MW, Ironside JW. The application of in vitro cell-free conversion systems to human prion diseases. Acta Neuropathol 2011; 121:135-43. [PMID: 20535485 DOI: 10.1007/s00401-010-0708-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 05/20/2010] [Accepted: 05/30/2010] [Indexed: 01/15/2023]
Abstract
A key event in the pathogenesis of prion diseases is the conversion of the normal cellular isoform of the prion protein into the disease-associated isoform, but the mechanisms operating in this critical event are not yet fully understood. A number of novel approaches have recently been developed to study factors influencing this process. One of these, the protein misfolding cyclical amplification (PMCA) technique, has been used to explore defined factors influencing the conversion of cellular prion protein in a cell-free model system. Although initially developed in animal models, this technique has been increasingly applied to human prion diseases. Recent studies have focused on the role of different isoforms of the disease-associated human prion protein and the effects of the naturally occurring polymorphism at codon 129 in the human prion protein gene on the conversion process, improving our understanding of the interaction between host and agent factors that influence the wide range of phenotypes in human prion diseases. This technique also allows a greatly enhanced sensitivity of detection of disease-associated prion protein in human tissues and fluids, which is potentially applicable to disease screening, particularly for variant Creutzfeldt-Jakob disease. The PMCA technique can also be used to model human susceptibility to a range of prions of non-human origin, which is likely to prove of considerable future interest as more novel and potentially pathogenic prion diseases are identified in animal species that form part of the human food chain.
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Affiliation(s)
- Michael Jones
- Components and vCJD Research, National Science Laboratories, Scottish National Blood Transfusion Service, Edinburgh, EH 17 7QT, UK
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484
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Abstract
Prion diseases in humans and animals are characterized by progressive neurodegeneration and the formation of infectious particles called prions. Both features are intimately linked to a conformational transition of the cellular prion protein (PrP(C)) into aberrantly folded conformers with neurotoxic and self-replicating activities. Interestingly, there is increasing evidence that the infectious and neurotoxic properties of PrP conformers are not necessarily coupled. Transgenic mouse models revealed that some PrP mutants interfere with neuronal function in the absence of infectious prions. Vice versa, propagation of prions can occur without causing neurotoxicity. Consequently, it appears plausible that two partially independent pathways exist, one pathway leading to the propagation of infectious prions and another one that mediates neurotoxic signaling. In this review we will summarize current knowledge of neurotoxic PrP conformers and discuss the role of PrP(C) as a mediator of both stress-protective and neurotoxic signaling cascades.
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485
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Abstract
The conversion of the normal prion protein (PrP(C)) into its misfolded, aggregation-prone and infectious (prion) isoform is central to the progression of transmissible spongiform encephalopathies (TSEs) or prion diseases. Since the initial development of a cell free PrP conversion reaction, striking progress has been made in the development of much more continuous prion-induced conversion and amplification reactions. These studies have provided major insights into the molecular underpinnings of prion propagation and enabled the development of ultra-sensitive tests for prions and prion disease diagnosis. This chapter will provide an overview of such reactions and the practical and fundamental consequences of their development.
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Affiliation(s)
- Christina D Orrú
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
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486
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Abstract
The discovery of infectious proteins, denoted prions, was unexpected. After much debate over the chemical basis of heredity, resolution of this issue began with the discovery that DNA, not protein, from pneumococcus was capable of genetically transforming bacteria (Avery et al. 1944). Four decades later, the discovery that a protein could mimic viral and bacterial pathogens with respect to the transmission of some nervous system diseases (Prusiner 1982) met with great resistance. Overwhelming evidence now shows that Creutzfeldt-Jakob disease (CJD) and related disorders are caused by prions. The prion diseases are characterized by neurodegeneration and lethality. In mammals, prions reproduce by recruiting the normal, cellular isoform of the prion protein (PrP(C)) and stimulating its conversion into the disease-causing isoform (PrP(Sc)). PrP(C) and PrP(Sc) have distinct conformations: PrP(C) is rich in α-helical content and has little β-sheet structure, whereas PrP(Sc) has less α-helical content and is rich in β-sheet structure (Pan et al. 1993). The conformational conversion of PrP(C) to PrP(Sc) is the fundamental event underlying prion diseases. In this article, we provide an introduction to prions and the diseases they cause.
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Affiliation(s)
- David W Colby
- Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California 94143, USA
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487
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Abstract
Although prion diseases, such as Creutzfeldt-Jakob disease (CJD) in humans and scrapie in sheep, have long been recognized, our understanding of their epidemiology and pathogenesis is still in its early stages. Progress is hampered by the lengthy incubation periods and the lack of effective ways of monitoring and characterizing these agents. Protease-resistant conformers of the prion protein (PrP), known as the "scrapie form" (PrP(Sc)), are used as disease markers, and for taxonomic purposes, in correlation with clinical, pathological, and genetic data. In humans, prion diseases can arise sporadically (sCJD) or genetically (gCJD and others), caused by mutations in the PrP-gene (PRNP), or as a foodborne infection, with the agent of bovine spongiform encephalopathy (BSE) causing variant CJD (vCJD). Person-to-person spread of human prion disease has only been known to occur following cannibalism (kuru disease in Papua New Guinea) or through medical or surgical treatment (iatrogenic CJD, iCJD). In contrast, scrapie in small ruminants and chronic wasting disease (CWD) in cervids behave as infectious diseases within these species. Recently, however, so-called atypical forms of prion diseases have been discovered in sheep (atypical/Nor98 scrapie) and in cattle, BSE-H and BSE-L. These maladies resemble sporadic or genetic human prion diseases and might be their animal equivalents. This hypothesis also raises the significant public health question of possible epidemiological links between these diseases and their counterparts in humans.
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488
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Park KW, Li L. Prion protein in Caenorhabditis elegans: Distinct models of anti-BAX and neuropathology. Prion 2011; 5:28-38. [PMID: 21084837 DOI: 10.4161/pri.5.1.14026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The infectious agent of prion diseases is believed to be nucleic acid-free particles composed of misfolded conformational isomers of a host protein known as prion protein (PrP). Although this "protein-only" concept is generally accepted, decades of extensive research have not been able to elucidate the mechanisms by which PrP misfolding leads to neurodegeneration and infectivity. The challenges in studying prion diseases relate in part to the limitations of mammalian prion models, which include the long incubation period post-infection until symptoms develop, the high expense of maintaining mammals for extended periods, as well as safety issues. In order to develop prion models incorporating a genetically tractable simple system with a well-defined neuronal system, we generated transgenic C. elegans expressing the mouse PrP behind the pan-neuronal ric-19 promoter (Pric-19). We show here that high expression of Pric-19::PrP in C. elegans can result in altered morphology, defective mobility, and shortened lifespan. Low expression of Pric-19::PrP, however, does not cause any detectable harm. Using the dopamine neuron specific promoter Pdat-1, we also show that expression of the murine BAX, a pro-apoptotic member of the Bcl-2 family, causes dopamine neuron destruction in the nematode. However, co-expression of PrP inhibits BAX-mediated dopamine neuron degeneration, demonstrating for the first time that PrP has anti-BAX activity in living animals. Thus, these distinct PrP-transgenic C. elegans lines recapitulate a number of functional and neuropathological features of mammalian prion models, and provide an opportunity for facile identification of genetic and environmental contributors to prion-associated pathology.
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Affiliation(s)
- Kyung-Won Park
- Department of Molecular Pharmacology and Biological Chemistry, The Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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489
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Prion protein and its conformational conversion: a structural perspective. Top Curr Chem (Cham) 2011; 305:135-67. [PMID: 21630136 DOI: 10.1007/128_2011_165] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The key molecular event in the pathogenesis of prion diseases is the conformational conversion of a cellular prion protein, PrP(C), into a misfolded form, PrP(Sc). In contrast to PrP(C) that is monomeric and α-helical, PrP(Sc) is oligomeric in nature and rich in β-sheet structure. According to the "protein-only" model, PrP(Sc) itself represents the infectious prion agent responsible for transmissibility of prion disorders. While this model is supported by rapidly growing experimental data, detailed mechanistic and structural aspects of prion protein conversion remain enigmatic. In this chapter we describe recent advances in understanding biophysical and biochemical aspects of prion diseases, with a special focus on structural underpinnings of prion protein conversion, the structural basis of prion strains, and generation of prion infectivity in vitro from bacterially-expressed recombinant PrP.
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490
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Guest WC, Silverman JM, Pokrishevsky E, O'Neill MA, Grad LI, Cashman NR. Generalization of the prion hypothesis to other neurodegenerative diseases: an imperfect fit. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:1433-1459. [PMID: 22043906 DOI: 10.1080/15287394.2011.618967] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Protein misfolding diseases have been classically understood as diffuse errors in protein folding, with misfolded protein arising autonomously throughout a tissue due to a pathologic stressor. The field of prion science has provided an alternative mechanism whereby a seed of pathologically misfolded protein, arising exogenously or through a rare endogenous structural fluctuation, yields a template to catalyze misfolding of the native protein. The misfolded protein may then spread intercellularly to communicate the misfold to adjacent areas and ultimately infect a whole tissue. Mounting evidence implicates a prion-like process in the propagation of several neurodegenerative diseases, including Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis, and the tauopathies. However, the parallels between the events observed in these conditions and those in prion disease are often incomplete. The aim of this review was to examine the current state of knowledge concerning the mechanisms of protein misfolding and aggregation for neurodegeneration-associated proteins. In addition, possible methods of intercellular spread are described that focus on the hypothesis that released microvesicles function as misfolded protein delivery vehicles, and the therapeutic options enabled by viewing these diseases from the prion perspective.
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Affiliation(s)
- Will C Guest
- Brain Research Centre, University of British Columbia, Vancouver, BC, Canada
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491
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Wang F, Wang X, Ma J. Conversion of bacterially expressed recombinant prion protein. Methods 2010; 53:208-13. [PMID: 21176786 DOI: 10.1016/j.ymeth.2010.12.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 12/10/2010] [Accepted: 12/15/2010] [Indexed: 10/18/2022] Open
Abstract
The infectivity associated with prion disease sets it apart from a large group of late-onset neurodegenerative disorders that shares the characteristics of protein aggregation and neurodegeneration. The unconventional infectious agent, PrP(Sc), is an aberrantly folded form of the normal prion protein (PrP(C)) and the PrP(C)-to-PrP(Sc) conversion is a critical pathogenic step in prion disease. Using the Protein Misfolding Cyclic Amplification technique, we converted folded bacterially expressed recombinant PrP into a proteinase K-resistant and aggregated conformation (rPrP-res) in the presence of anionic lipid and RNA molecules. Moreover, high prion infectivity was demonstrated by intracerebral inoculation of rPrP-res into wild-type mice, which caused prion disease with a short incubation period. The establishment of the in vitro recombinant PrP conversion assay makes it feasible for us to explore the molecular basis behind the intriguing properties associated with prion infectivity.
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Affiliation(s)
- Fei Wang
- Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210, USA
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492
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Affiliation(s)
- Jungsu Kim
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110, USA
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493
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Silva JL, Vieira TCRG, Gomes MPB, Rangel LP, Scapin SMN, Cordeiro Y. Experimental approaches to the interaction of the prion protein with nucleic acids and glycosaminoglycans: Modulators of the pathogenic conversion. Methods 2010; 53:306-17. [PMID: 21145399 DOI: 10.1016/j.ymeth.2010.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 12/02/2010] [Indexed: 11/17/2022] Open
Abstract
The concept that transmissible spongiform encephalopathies (TSEs) are caused only by proteins has changed the traditional paradigm that disease transmission is due solely to an agent that carries genetic information. The central hypothesis for prion diseases proposes that the conversion of a cellular prion protein (PrP(C)) into a misfolded, β-sheet-rich isoform (PrP(Sc)) accounts for the development of (TSE). There is substantial evidence that the infectious material consists chiefly of a protein, PrP(Sc), with no genomic coding material, unlike a virus particle, which has both. However, prions seem to have other partners that chaperone their activities in converting the PrP(C) into the disease-causing isoform. Nucleic acids (NAs) and glycosaminoglycans (GAGs) are the most probable accomplices of prion conversion. Here, we review the recent experimental approaches that have been employed to characterize the interaction of prion proteins with nucleic acids and glycosaminoglycans. A PrP recognizes many nucleic acids and GAGs with high affinities, and this seems to be related to a pathophysiological role for this interaction. A PrP binds nucleic acids and GAGs with structural selectivity, and some PrP:NA complexes can become proteinase K-resistant, undergoing amyloid oligomerization and conversion to a β-sheet-rich structure. These results are consistent with the hypothesis that endogenous polyanions (such as NAs and GAGs) may accelerate the rate of prion disease progression by acting as scaffolds or lattices that mediate the interaction between PrP(C) and PrP(Sc) molecules. In addition to a still-possible hypothesis that nucleic acids and GAGs, especially those from the host, may modulate the conversion, the recent structural characterization of the complexes has raised the possibility of developing new diagnostic and therapeutic strategies.
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Affiliation(s)
- Jerson L Silva
- Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Brazil.
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494
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Soto C. Prion hypothesis: the end of the controversy? Trends Biochem Sci 2010; 36:151-8. [PMID: 21130657 DOI: 10.1016/j.tibs.2010.11.001] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 11/03/2010] [Accepted: 11/04/2010] [Indexed: 01/25/2023]
Abstract
Forty-three years have passed since it was first proposed that a protein could be the sole component of the infectious agent responsible for the enigmatic prion diseases. Many discoveries have strongly supported the prion hypothesis, but only recently has this once heretical hypothesis been widely accepted by the scientific community. In the past 3 years, researchers have achieved the 'Holy Grail' demonstration that infectious material can be generated in vitro using completely defined components. These breakthroughs have proven that a misfolded protein is the active component of the infectious agent, and that propagation of the disease and its unique features depend on the self-replication of the infectious folding of the prion protein. In spite of these important discoveries, it remains unclear whether another molecule besides the misfolded prion protein might be an essential element of the infectious agent. Future research promises to reveal many more intriguing features about the rogue prions.
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Affiliation(s)
- Claudio Soto
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, The University of Texas Medical school at Houston, 6431 Fannin St, Houston, TX 77030, USA.
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495
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Mays CE, Ryou C. Plasminogen stimulates propagation of protease‐resistant prion protein
in vitro. FASEB J 2010. [DOI: 10.1096/fj.10.163600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Charles E. Mays
- Sanders‐Brown Center on AgingDepartment of MicrobiologyImmunology and Molecular GeneticsUniversity of Kentucky College of Medicine Lexington Kentucky USA
| | - Chongsuk Ryou
- Sanders‐Brown Center on AgingDepartment of MicrobiologyImmunology and Molecular GeneticsUniversity of Kentucky College of Medicine Lexington Kentucky USA
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496
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Wickner RB, Shewmaker F, Edskes H, Kryndushkin D, Nemecek J, McGlinchey R, Bateman D, Winchester CL. Prion amyloid structure explains templating: how proteins can be genes. FEMS Yeast Res 2010. [PMID: 20726897 DOI: 10.1111/j.1567-364.2010.00666.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The yeast and fungal prions determine heritable and infectious traits, and are thus genes composed of protein. Most prions are inactive forms of a normal protein as it forms a self-propagating filamentous β-sheet-rich polymer structure called amyloid. Remarkably, a single prion protein sequence can form two or more faithfully inherited prion variants, in effect alleles of these genes. What protein structure explains this protein-based inheritance? Using solid-state nuclear magnetic resonance, we showed that the infectious amyloids of the prion domains of Ure2p, Sup35p and Rnq1p have an in-register parallel architecture. This structure explains how the amyloid filament ends can template the structure of a new protein as it joins the filament. The yeast prions [PSI(+)] and [URE3] are not found in wild strains, indicating that they are a disadvantage to the cell. Moreover, the prion domains of Ure2p and Sup35p have functions unrelated to prion formation, indicating that these domains are not present for the purpose of forming prions. Indeed, prion-forming ability is not conserved, even within Saccharomyces cerevisiae, suggesting that the rare formation of prions is a disease. The prion domain sequences generally vary more rapidly in evolution than does the remainder of the molecule, producing a barrier to prion transmission, perhaps selected in evolution by this protection.
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Affiliation(s)
- Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
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497
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Appleby BS, Lyketsos CG. Rapidly progressive dementias and the treatment of human prion diseases. Expert Opin Pharmacother 2010; 12:1-12. [PMID: 21091283 DOI: 10.1517/14656566.2010.514903] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
IMPORTANCE OF THE FIELD Rapidly progressive dementia (RPD) has many possible etiologies and definitive treatment is reliant upon an accurate diagnosis from an appropriate diagnostic work-up. A large portion of the neurodegenerative causes of RPD are due to prion diseases (e.g., Creutzfeldt-Jakob disease). The study of prion diseases, for which there is no currently available treatment, has public health implications and is becoming increasingly more relevant to our understanding of other protein misfolding disorders including Alzheimer's disease, frontotemporal degeneration, and Parkinson's disease. AREAS COVERED IN THIS REVIEW This article begins with an overview of the etiologies and diagnostic work-up of RPD followed by a detailed review of the literature concerning the treatment of human prion diseases (1971 to present). WHAT THE READER WILL GAIN The reader will understand the differential diagnosis and work-up of RPD as it pertains to its treatment, as well as an in-depth understanding of treatments of human prion diseases. TAKE HOME MESSAGE An accurate diagnosis of the cause of RPD is of paramount importance when determining appropriate treatment. Most studies of the treatment for human prion diseases are case reports or case series, and results from only one randomized, placebo-controlled study have been reported in the literature (flupirtine). Studies have been hindered by disease heterogeneity and lack of standardized outcome measures. Although no effective prion disease treatment has been revealed through these studies, they provide important considerations for future studies.
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Affiliation(s)
- Brian S Appleby
- Johns Hopkins University School of Medicine, Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Meyer 279, 600 N. Wolfe St., Baltimore, MD 21287, USA.
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498
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Rossetti G, Giachin G, Legname G, Carloni P. Structural facets of disease-linked human prion protein mutants: A molecular dynamic study. Proteins 2010; 78:3270-80. [PMID: 20806222 DOI: 10.1002/prot.22834] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Giulia Rossetti
- Statistical and Biological Physics Sector, International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy
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499
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Choi YP, Gröner A, Ironside JW, Head MW. Correlation of polydispersed prion protein and characteristic pathology in the thalamus in variant Creutzfeldt-Jakob disease: implication of small oligomeric species. Brain Pathol 2010; 21:298-307. [PMID: 21029243 DOI: 10.1111/j.1750-3639.2010.00446.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The vacuolation, neuronal loss and gliosis that characterize human prion disease pathology are accompanied by the accumulation of an aggregated, insoluble and protease-resistant form (termed PrP(Sc)) of the host-encoded normal cellular prion protein (PrP(C)). In variant Creutzfeldt-Jakob disease the frontal cortex and cerebellum exhibit intense vacuolation and the accumulation of PrP(Sc) in the form of amyloid plaques and plaque-like structures. In contrast the posterior thalamus is characterized by intense gliosis and neuronal loss, but PrP(Sc) plaques are rare and vacuolation is patchy. We have used sucrose density gradient centrifugation coupled with conformation dependent immunoassay to examine the biochemical properties of the PrP(Sc) that accumulates in these different brain regions. The results show a greater degree of PrP(Sc) polydisperal in thalamus compared with frontal cortex or cerebellum, including a subpopulation PrP(Sc) molecules in the thalamus that have sedimentation properties resembling those of PrP(C). Much effort has focused on identifying aspects of PrP(Sc) biochemistry that distinguish between different forms of human prion disease and contribute to differential diagnosis. Here we show that PrP(Sc) sedimentation properties, which can depend on aggregation state, correlate with, and may underlie the distinct neurodegenerative processes occurring in different regions of the variant Creutzfeldt-Jakob disease brain.
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Affiliation(s)
- Young Pyo Choi
- National Creutzfeldt-Jakob Disease Surveillance Unit, School of Molecular and Clinical Medicine (Pathology), University of Edinburgh, Edinburgh, UK
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500
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Giraldo R. Amyloid Assemblies: Protein Legos at a Crossroads in Bottom-Up Synthetic Biology. Chembiochem 2010; 11:2347-57. [DOI: 10.1002/cbic.201000412] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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