351
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Abstract
The aggregation and deposition of amyloid-β (Aβ) peptides are believed to be central events in the pathogenesis of Alzheimer's disease (AD). Inoculation of brain homogenates containing Aβ aggregates into susceptible transgenic mice accelerated Aβ deposition, suggesting that Aβ aggregates are capable of self-propagation and hence might be prions. Recently, we demonstrated that Aβ deposition can be monitored in live mice using bioluminescence imaging (BLI). Here, we use BLI to probe the ability of Aβ aggregates to self-propagate following inoculation into bigenic mice. We report compelling evidence that Aβ aggregates are prions by demonstrating widespread cerebral β-amyloidosis induced by inoculation of either purified Aβ aggregates derived from brain or aggregates composed of synthetic Aβ. Although synthetic Aβ aggregates were sufficient to induce Aβ deposition in vivo, they exhibited lower specific biological activity compared with brain-derived Aβ aggregates. Our results create an experimental paradigm that should lead to identification of self-propagating Aβ conformations, which could represent novel targets for interrupting the spread of Aβ deposition in AD patients.
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352
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Invernizzi G, Papaleo E, Sabate R, Ventura S. Protein aggregation: mechanisms and functional consequences. Int J Biochem Cell Biol 2012; 44:1541-54. [PMID: 22713792 DOI: 10.1016/j.biocel.2012.05.023] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/09/2012] [Accepted: 05/27/2012] [Indexed: 12/31/2022]
Abstract
Understanding the mechanisms underlying protein misfolding and aggregation has become a central issue in biology and medicine. Compelling evidence show that the formation of amyloid aggregates has a negative impact in cell function and is behind the most prevalent human degenerative disorders, including Alzheimer's Parkinson's and Huntington's diseases or type 2 diabetes. Surprisingly, the same type of macromolecular assembly is used for specialized functions by different organisms, from bacteria to human. Here we address the conformational properties of these aggregates, their formation pathways, their role in human diseases, their functional properties and how bioinformatics tools might be of help to study these protein assemblies.
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Affiliation(s)
- Gaetano Invernizzi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
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353
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Affiliation(s)
- Sven J Saupe
- IBGC, UMR 5095 CNRS Université de Bordeaux 2, Bordeaux, France.
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354
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Nwankiti OO, Ikeh EI, Asala O, Seuberlich T. A Pilot Study for Targeted Surveillance of Bovine Spongiform Encephalopathy in Nigeria. Transbound Emerg Dis 2012; 60:279-83. [DOI: 10.1111/j.1865-1682.2012.01340.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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355
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Schneider DA, Harrington RD, Zhuang D, Yan H, Truscott TC, Dassanayake RP, O'Rourke KI. Disease-associated prion protein in neural and lymphoid tissues of mink (Mustela vison) inoculated with transmissible mink encephalopathy. J Comp Pathol 2012; 147:508-21. [PMID: 22595634 DOI: 10.1016/j.jcpa.2012.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 03/13/2012] [Accepted: 03/31/2012] [Indexed: 11/18/2022]
Abstract
Transmissible spongiform encephalopathies (TSEs) are diagnosed by immunodetection of disease-associated prion protein (PrP(d)). The distribution of PrP(d) within the body varies with the time-course of infection and between species, during interspecies transmission, as well as with prion strain. Mink are susceptible to a form of TSE known as transmissible mink encephalopathy (TME), presumed to arise due to consumption of feed contaminated with a single prion strain of ruminant origin. After extended passage of TME isolates in hamsters, two strains emerge, HY and DY, each of which is associated with unique structural isoforms of PrP(TME) and of which only the HY strain is associated with accumulation of PrP(TME) in lymphoid tissues. Information on the structural nature and lymphoid accumulation of PrP(TME) in mink is limited. In this study, 13 mink were challenged by intracerebral inoculation using late passage TME inoculum, after which brain and lymphoid tissues were collected at preclinical and clinical time points. The distribution and molecular nature of PrP(TME) was investigated by techniques including blotting of paraffin wax-embedded tissue and epitope mapping by western blotting. PrP(TME) was detected readily in the brain and retropharyngeal lymph node during preclinical infection, with delayed progression of accumulation within other lymphoid tissues. For comparison, three mink were inoculated by the oral route and examined during clinical disease. Accumulation of PrP(TME) in these mink was greater and more widespread, including follicles of rectoanal mucosa-associated lymphoid tissue. Western blot analyses revealed that PrP(TME) accumulating in the brain of mink is structurally most similar to that accumulating in the brain of hamsters infected with the DY strain. Collectively, the results of extended passage in mink are consistent with the presence of only a single strain of TME, the DY strain, capable of inducing accumulation of PrP(TME) in the lymphoid tissues of mink but not in hamsters. Thus, mink are a relevant animal model for further study of this unique strain, which ultimately may have been introduced through consumption of a TSE of ruminant origin.
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Affiliation(s)
- D A Schneider
- Animal Disease Research Unit, Agricultural Research Service, US Department of Agriculture, Pullman, WA 99164-6630, USA.
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356
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Seuberlich T, Gsponer M, Drögemüller C, Polak MP, McCutcheon S, Heim D, Oevermann A, Zurbriggen A. Novel prion protein in BSE-affected cattle, Switzerland. Emerg Infect Dis 2012; 18:158-9. [PMID: 22261120 PMCID: PMC3310124 DOI: 10.3201/eid1801.111225] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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357
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Abstract
Amyloid fibers and oligomers are associated with a great variety of human diseases including Alzheimer's disease and the prion conditions. Here we attempt to connect recent discoveries on the molecular properties of proteins in the amyloid state with observations about pathological tissues and disease states. We summarize studies of structure and nucleation of amyloid and relate these to observations on amyloid polymorphism, prion strains, coaggregation of pathogenic proteins in tissues, and mechanisms of toxicity and transmissibility. Molecular studies have also led to numerous strategies for biological and chemical interventions against amyloid diseases.
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Affiliation(s)
- David Eisenberg
- Howard Hughes Medical Institute, Department of Biological Chemistry, University of California, Los Angeles, Los Angeles CA 90095-1570, USA.
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358
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Dunning CJ, Reyes JF, Steiner JA, Brundin P. Can Parkinson's disease pathology be propagated from one neuron to another? Prog Neurobiol 2012; 97:205-19. [DOI: 10.1016/j.pneurobio.2011.11.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 11/02/2011] [Accepted: 11/08/2011] [Indexed: 12/12/2022]
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359
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Differential activation of the ER stress factor XBP1 by oligomeric assemblies. Neurochem Res 2012; 37:1707-17. [PMID: 22528838 PMCID: PMC3387497 DOI: 10.1007/s11064-012-0780-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 03/23/2012] [Accepted: 04/04/2012] [Indexed: 12/25/2022]
Abstract
Several neurodegenerative disorders are characterized by protein misfolding, a phenomenon that results in perturbation of cellular homeostasis. We recently identified the protective activity of the ER stress response factor XBP1 (X-box binding protein 1) against Amyloid-ß1-42 (Aß42) neurotoxicity in cellular and Drosophila models of Alzheimer’s disease. Additionally, subtoxic concentrations of Aß42 soluble aggregates (oligomers) induced accumulation of spliced (active) XBP1 transcripts, supporting the involvement of the ER stress response in Aß42 neurotoxicity. Here, we tested the ability of three additional disease-related amyloidogenic proteins to induce ER stress by analyzing XBP1 activation at the RNA level. Treatment of human SY5Y neuroblastoma cells with homogeneous preparations of α-Synuclein (α-Syn), Prion protein (PrP106–126), and British dementia amyloid peptide (ABri1-34) confirmed the high toxicity of oligomers compared to monomers and fibers. Additionally, α-Syn oligomers, but not monomers or fibers, demonstrated potent induction of XBP1 splicing. On the other hand, PrP106–126 and ABri1-34 did not activate XBP1. These results illustrate the biological complexity of these structurally related assemblies and argue that oligomer toxicity depends on the activation of amyloid-specific cellular responses.
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360
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Hansen C, Li JY. Beyond α-synuclein transfer: pathology propagation in Parkinson's disease. Trends Mol Med 2012; 18:248-55. [PMID: 22503115 DOI: 10.1016/j.molmed.2012.03.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 02/29/2012] [Accepted: 03/05/2012] [Indexed: 02/08/2023]
Abstract
α-Synuclein (α-syn) is the most abundant protein found in Lewy bodies, a hallmark of Parkinson's disease (PD), and can aggregate to form toxic oligomers and fibrillar structures. Recent studies have shown that α-syn can be transmitted between neurons and can seed the formation of toxic aggregates in recipient neurons in a prion-like manner. In addition, it is known that Lewy body pathology may spread gradually and systematically from the peripheral or enteric nervous system or olfactory bulb to specific brain regions during progression of idiopathic PD. It is therefore conceivable that α-syn species could act as seeds that drive PD progression. Here, we review recent advances from studies of α-syn cell-to-cell transfer, the current understanding of α-syn toxicity, and how these relate to progression of PD pathology.
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Affiliation(s)
- Christian Hansen
- Neural Plasticity and Repair Unit, Wallenberg Neuroscience Center, Lund University, BMC A10 22184, Lund, Sweden
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361
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Miyazawa K, Emmerling K, Manuelidis L. High CJD infectivity remains after prion protein is destroyed. J Cell Biochem 2012; 112:3630-7. [PMID: 21793041 DOI: 10.1002/jcb.23286] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The hypothesis that host prion protein (PrP) converts into an infectious prion form rests on the observation that infectivity progressively decreases in direct proportion to the decrease of PrP with proteinase K (PK) treatment. PrP that resists limited PK digestion (PrP-res, PrP(sc)) has been assumed to be the infectious form, with speculative types of misfolding encoding the many unique transmissible spongiform encephalopathy (TSE) agent strains. Recently, a PK sensitive form of PrP has been proposed as the prion. Thus we re-evaluated total PrP (sensitive and resistant) and used a cell-based assay for titration of infectious particles. A keratinase (NAP) known to effectively digest PrP was compared to PK. Total PrP in FU-CJD infected brain was reduced to ≤0.3% in a 2 h PK digest, yet there was no reduction in titer. Remaining non-PrP proteins were easily visualized with colloidal gold in this highly infectious homogenate. In contrast to PK, NAP digestion left 0.8% residual PrP after 2 h, yet decreased titer by >2.5 log; few residual protein bands remained. FU-CJD infected cells with 10× the infectivity of brain by both animal and cell culture assays were also evaluated. NAP again significantly reduced cell infectivity (>3.5 log). Extreme PK digestions were needed to reduce cell PrP to <0.2%, yet a very high titer of 8 logs survived. Our FU-CJD brain results are in good accord with the only other report on maximal PrP destruction and titer. It is likely that one or more residual non-PrP proteins may protect agent nucleic acids in infectious particles.
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Affiliation(s)
- Kohtaro Miyazawa
- Department of Surgery, Yale Medical School, New Haven, Connecticut 06511, USA
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362
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Friedman-Levi Y, Hoftberger R, Budka H, Mayer-Sonnenfeld T, Abramsky O, Ovadia H, Gabizon R. Targeting of prion-infected lymphoid cells to the central nervous system accelerates prion infection. J Neuroinflammation 2012; 9:58. [PMID: 22436404 PMCID: PMC3347999 DOI: 10.1186/1742-2094-9-58] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 03/21/2012] [Indexed: 12/11/2022] Open
Abstract
Background Prions, composed of a misfolded protein designated PrPSc, are infectious agents causing fatal neurodegenerative diseases. We have shown previously that, following induction of experimental autoimmune encephalomyelitis, prion-infected mice succumb to disease significantly earlier than controls, concomitant with the deposition of PrPSc aggregates in inflamed white matter areas. In the present work, we asked whether prion disease acceleration by experimental autoimmune encephalomyelitis results from infiltration of viable prion-infected immune cells into the central nervous system. Methods C57Bl/6 J mice underwent intraperitoneal inoculation with scrapie brain homogenates and were later induced with experimental autoimmune encephalomyelitis by inoculation of MOG35-55 in complete Freund's adjuvant supplemented with pertussis toxin. Spleen and lymph node cells from the co-induced animals were reactivated and subsequently injected into naïve mice as viable cells or as cell homogenates. Control groups were infected with viable and homogenized scrapie immune cells only with complete Freund's adjuvant. Prion disease incubation times as well as levels and sites of PrPSc deposition were next evaluated. Results We first show that acceleration of prion disease by experimental autoimmune encephalomyelitis requires the presence of high levels of spleen PrPSc. Next, we present evidence that mice infected with activated prion-experimental autoimmune encephalomyelitis viable cells succumb to prion disease considerably faster than do mice infected with equivalent cell extracts or other controls, concomitant with the deposition of PrPSc aggregates in white matter areas in brains and spinal cords. Conclusions Our results indicate that inflammatory targeting of viable prion-infected immune cells to the central nervous system accelerates prion disease propagation. We also show that in the absence of such targeting it is the load of PrPSc in the inoculum that determines the infectivity titers for subsequent transmissions. Both of these conclusions have important clinical implications as related to the risk of prion disease contamination of blood products.
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Affiliation(s)
- Yael Friedman-Levi
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital, Jerusalem, Israel
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363
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Affiliation(s)
- Christopher D. Link
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309, USA
| | - Tassa K. Saldi
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309, USA
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364
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Spontaneous generation of rapidly transmissible prions in transgenic mice expressing wild-type bank vole prion protein. Proc Natl Acad Sci U S A 2012; 109:3498-503. [PMID: 22331873 DOI: 10.1073/pnas.1121556109] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Currently, there are no animal models of the most common human prion disorder, sporadic Creutzfeldt-Jakob disease (CJD), in which prions are formed spontaneously from wild-type (WT) prion protein (PrP). Interestingly, bank voles (BV) exhibit an unprecedented promiscuity for diverse prion isolates, arguing that bank vole PrP (BVPrP) may be inherently prone to adopting misfolded conformations. Therefore, we constructed transgenic (Tg) mice expressing WT BVPrP. Tg(BVPrP) mice developed spontaneous CNS dysfunction between 108 and 340 d of age and recapitulated the hallmarks of prion disease, including spongiform degeneration, pronounced astrogliosis, and deposition of alternatively folded PrP in the brain. Brain homogenates of ill Tg(BVPrP) mice transmitted disease to Tg(BVPrP) mice in ∼35 d, to Tg mice overexpressing mouse PrP in under 100 d, and to WT mice in ∼185 d. Our studies demonstrate experimentally that WT PrP can spontaneously form infectious prions in vivo. Thus, Tg(BVPrP) mice may be useful for studying the spontaneous formation of prions, and thus may provide insight into the etiology of sporadic CJD.
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365
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Buxbaum JN, Linke RP. A molecular history of the amyloidoses. J Mol Biol 2012; 421:142-59. [PMID: 22321796 DOI: 10.1016/j.jmb.2012.01.024] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 01/07/2012] [Accepted: 01/18/2012] [Indexed: 11/30/2022]
Abstract
The molecular investigation of the amyloidoses began in the mid-19th century with the observation of areas in human tissues obtained at autopsy that were homogeneous and eosinophilic with conventional stains but became blue when exposed to mixtures of iodine and sulfuric acid. The foci corresponded to regions formerly identified as "waxy" or lardaceous. Subsequent identification of the characteristic staining of the same tissues with metachromatic dyes such as crystal violet or with the cotton dye Congo red (particularly under polarized light) and thioflavins allowed the pathological classification of those tissues as belonging to a set of disorders known as the amyloidoses. Not unexpectedly, progress has reflected evolving technology and parallel advances in all fields of biological science. Investigation using contemporary methods has expanded our notions of amyloid proteins from being simply agents or manifestations of systemic, largely extracellular diseases to include "protein-only infection," the concept that "normal" functional amyloids might exist in eukaryotes and prokaryotes and that aggregatability may be an intrinsic structural price to be paid for some functional protein domains. We now distinguish between the amyloidoses, that is, diseases caused by the deposition of amyloid fibrils and amyloid proteins (i.e., purified or recombinant proteins that form amyloid fibrils in vitro), which may or may not be associated with disease in vivo.
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Affiliation(s)
- Joel N Buxbaum
- Department of Molecular and Experimental Medicine (MEM230), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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366
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Despa S, Margulies KB, Chen L, Knowlton AA, Havel PJ, Taegtmeyer H, Bers DM, Despa F. Hyperamylinemia contributes to cardiac dysfunction in obesity and diabetes: a study in humans and rats. Circ Res 2012; 110:598-608. [PMID: 22275486 DOI: 10.1161/circresaha.111.258285] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Hyperamylinemia is common in patients with obesity and insulin resistance, coincides with hyperinsulinemia, and results in amyloid deposition. Amylin amyloids are generally considered a pancreatic disorder in type 2 diabetes. However, elevated circulating levels of amylin may also lead to amylin accumulation and proteotoxicity in peripheral organs, including the heart. OBJECTIVE To test whether amylin accumulates in the heart of obese and type 2 diabetic patients and to uncover the effects of amylin accumulation on cardiac morphology and function. METHODS AND RESULTS We compared amylin deposition in failing and nonfailing hearts from lean, obese, and type 2 diabetic humans using immunohistochemistry and Western blots. We found significant accumulation of large amylin oligomers, fibrils, and plaques in failing hearts from obese and diabetic patients but not in normal hearts and failing hearts from lean, nondiabetic humans. Small amylin oligomers were even elevated in nonfailing hearts from overweight/obese patients, suggesting an early state of accumulation. Using a rat model of hyperamylinemia transgenic for human amylin, we observed that amylin oligomers attach to the sarcolemma, leading to myocyte Ca(2+) dysregulation, pathological myocyte remodeling, and diastolic dysfunction, starting from prediabetes. In contrast, prediabetic rats expressing the same level of wild-type rat amylin, a nonamyloidogenic isoform, exhibited normal heart structure and function. CONCLUSIONS Hyperamylinemia promotes amylin deposition in the heart, causing alterations of cardiac myocyte structure and function. We propose that detection and disruption of cardiac amylin buildup may be both a predictor of heart dysfunction and a novel therapeutic strategy in diabetic cardiomyopathy.
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Affiliation(s)
- Sanda Despa
- Department of Pharmacology, University of California-Davis, 451 Health Sciences Drive, Davis, CA 95616, USA.
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367
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Abskharon RNN, Ramboarina S, El Hassan H, Gad W, Apostol MI, Giachin G, Legname G, Steyaert J, Messens J, Soror SH, Wohlkonig A. A novel expression system for production of soluble prion proteins in E. coli. Microb Cell Fact 2012; 11:6. [PMID: 22233534 PMCID: PMC3283519 DOI: 10.1186/1475-2859-11-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 01/10/2012] [Indexed: 11/16/2022] Open
Abstract
Expression of eukaryotic proteins in Escherichia coli is challenging, especially when they contain disulfide bonds. Since the discovery of the prion protein (PrP) and its role in transmissible spongiform encephalopathies, the need to obtain large quantities of the recombinant protein for research purposes has been essential. Currently, production of recombinant PrP is achieved by refolding protocols. Here, we show that the co-expression of two different PrP with the human Quiescin Sulfhydryl OXidase (QSOX), a human chaperone with thiol/disulfide oxidase activity, in the cytoplasm of E. coli produces soluble recombinant PrP. The structural integrity of the soluble PrP has been confirmed by nuclear magnetic resonance spectroscopy, demonstrating that properly folded PrP can be easily expressed in bacteria. Furthermore, the soluble recombinant PrP produced with this method can be used for functional and structural studies.
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368
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Abstract
Cerebral β-amyloidosis and associated pathologies can be exogenously induced by the intracerebral injection of small amounts of pathogenic Aβ-containing brain extract into young β-amyloid precursor protein (APP) transgenic mice. The probable β-amyloid-inducing factor in the brain extract has been identified as a species of aggregated Aβ that is generated in its most effective conformation or composition in vivo. Here we report that Aβ in the brain extract is more proteinase K (PK) resistant than is synthetic fibrillar Aβ, and that this PK-resistant fraction of the brain extract retains the capacity to induce β-amyloid deposition upon intracerebral injection in young, pre-depositing APP23 transgenic mice. After ultracentrifugation of the brain extract, <0.05% of the Aβ remained in the supernatant fraction, and these soluble Aβ species were largely PK sensitive. However, upon intracerebral injection, this soluble fraction accounted for up to 30% of the β-amyloid induction observed with the unfractionated extract. Fragmentation of the Aβ seeds by extended sonication increased the seeding capacity of the brain extract. In summary, these results suggest that multiple Aβ assemblies, with various PK sensitivities, are capable of inducing β-amyloid aggregation in vivo. The finding that small and soluble Aβ seeds are potent inducers of cerebral β-amyloidosis raises the possibility that such seeds may mediate the spread of β-amyloidosis in the brain. If they can be identified in vivo, soluble Aβ seeds in bodily fluids also could serve as early biomarkers for cerebral β-amyloidogenesis and eventually Alzheimer's disease.
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369
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Li J, Mahal SP, Demczyk CA, Weissmann C. Mutability of prions. EMBO Rep 2011; 12:1243-50. [PMID: 21997293 PMCID: PMC3245691 DOI: 10.1038/embor.2011.191] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/06/2011] [Accepted: 09/08/2011] [Indexed: 11/17/2022] Open
Abstract
Prions are shown to be mutable, and prion substrains have distinct mutation capacity. However, even clones that seem virtually immutable change when the environmental conditions are altered. Mutability is thus a prion substrain-specific attribute. Murine prions transferred from brain to cultured cells gradually adapt to the new environment. Brain-derived 22L prions can infect neuroblastoma-derived PK1 cells in the presence of swainsonine (swa); that is, they are ‘swa resistant'. PK1 cell-adapted 22L prions are swa sensitive; however, propagation in swa results in selection of swa-resistant substrains. Cloned, PK1 cell-adapted 22L prions were initially unable to develop swa resistance (‘swa incompetent'); however, after serial propagation for 30–90 doublings, four of nine clones became swa competent, showing that swa-resistant ‘mutants' arose during replication. Mutations in the case of prions are attributed to heritable changes in PrPSc conformation. One clone remained swa incompetent even after 1035-fold expansion; surprisingly, after propagation in brain, it yielded swa-resistant prions, indistinguishable from the original 22L population. Thus, cell-adapted 22L prions assumed either mutable or virtually immutable conformations; however, when passaged through the brain all became mutable. Mutability is thus a substrain-specific attribute.
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Affiliation(s)
- Jiali Li
- Department of Infectology, Scripps Florida, 130 Scripps Way, Jupiter, Florida 33458, USA
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370
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Goldmann W, Ryan K, Stewart P, Parnham D, Xicohtencatl R, Fernandez N, Saunders G, Windl O, González L, Bossers A, Foster J. Caprine prion gene polymorphisms are associated with decreased incidence of classical scrapie in goat herds in the United Kingdom. Vet Res 2011; 42:110. [PMID: 22040234 PMCID: PMC3224758 DOI: 10.1186/1297-9716-42-110] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/31/2011] [Indexed: 12/31/2022] Open
Abstract
The application of genetic breeding programmes to eradicate transmissible spongiform encephalopathies in goats is an important aim for reasons of animal welfare as well as human food safety and food security. Based on the positive impact of Prnp genetics on sheep scrapie in Europe in the past decade, we have established caprine Prnp gene variation in more than 1100 goats from the United Kingdom and studied the association of Prnp alleles with disease phenotypes in 150 scrapie-positive goats. This investigation confirms the association of the Met142 encoding Prnp allele with increased resistance to preclinical and clinical scrapie. It reveals a novel association of the Ser127 encoding allele with a reduced probability to develop clinical signs of scrapie in goats that are already positive for the accumulation of disease-specific prion protein in brain or periphery. A United Kingdom survey of Prnp genotypes in eight common breeds revealed eleven alleles in over thirty genotypes. The Met142 encoding allele had a high overall mean allele frequency of 22.6%, whereas the Ser127 encoding allele frequency was considerably lower with 6.4%. In contrast, a well known resistance associated allele encoding Lys222 was found to be rare (0.9%) in this survey. The analysis of Prnp genotypes in Mexican Criollas goats revealed nine alleles, including a novel Phe to Leu substitution in codon 201, confirming that high genetic variability of Prnp can be found in scrapie-free populations. Our study implies that it should be feasible to lower scrapie prevalence in goat herds in the United Kingdom by genetic selection.
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Affiliation(s)
- Wilfred Goldmann
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK
| | - Kelly Ryan
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK
| | - Paula Stewart
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK
| | - David Parnham
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK
| | - Rosa Xicohtencatl
- Facultad de Medicina Veterinaria y Zootecnia, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Nora Fernandez
- Facultad de Medicina Veterinaria y Zootecnia, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Ginny Saunders
- Animal Health and Veterinary Laboratories Agency, Weybridge, New Haw, Addlestone, Surrey, UK
| | - Otto Windl
- Animal Health and Veterinary Laboratories Agency, Weybridge, New Haw, Addlestone, Surrey, UK
| | - Lorenzo González
- Animal Health and Veterinary Laboratories Agency, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, UK
| | - Alex Bossers
- Central Veterinary Institute of Wageningen UR, Lelystad, The Netherlands
| | - James Foster
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK
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371
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Stein KC, True HL. The [RNQ+] prion: a model of both functional and pathological amyloid. Prion 2011; 5:291-8. [PMID: 22052347 DOI: 10.4161/pri.18213] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The formation of fibrillar amyloid is most often associated with protein conformational disorders such as prion diseases, Alzheimer disease and Huntington disease. Interestingly, however, an increasing number of studies suggest that amyloid structures can sometimes play a functional role in normal biology. Several proteins form self-propagating amyloids called prions in the budding yeast Saccharomyces cerevisiae. These unique elements operate by creating a reversible, epigenetic change in phenotype. While the function of the non-prion conformation of the Rnq1 protein is unclear, the prion form, [RNQ+], acts to facilitate the de novo formation of other prions to influence cellular phenotypes. The [RNQ+] prion itself does not adversely affect the growth of yeast, but the overexpression of Rnq1p can form toxic aggregated structures that are not necessarily prions. The [RNQ+] prion is also involved in dictating the aggregation and toxicity of polyglutamine proteins ectopically expressed in yeast. Thus, the [RNQ+] prion provides a tractable model that has the potential to reveal significant insight into the factors that dictate how amyloid structures are initiated and propagated in both physiological and pathological contexts.
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Affiliation(s)
- Kevin C Stein
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
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372
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Abstract
The MAVS protein plays a critical role in the assembly of an antiviral signaling complex on mitochondrial membranes. Hou et al. (2011) now report that virus infection induces a conformational change in MAVS, leading to the prion-like formation of functional self-aggregates that provide a sensitive trigger for antiviral signaling.
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Affiliation(s)
- Junqiang Ye
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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373
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Abstract
Prions are self-replicating proteins that can cause neurodegenerative disorders such as bovine spongiform encephalopathy (also known as mad cow disease). Aberrant conformations of prion proteins accumulate in the central nervous system, causing spongiform changes in the brain and eventually death. Since the inception of the prion hypothesis - which states that misfolded proteins are the infectious agents that cause these diseases - researchers have sought to generate infectious proteins from defined components in the laboratory with varying degrees of success. Here, we discuss several recent studies that have produced an array of novel prion strains in vitro that exhibit increasingly high titres of infectivity. These advances promise unprecedented insight into the structure of prions and the mechanisms by which they originate and propagate.
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Affiliation(s)
- David W. Colby
- Department of Chemical Engineering, University of Delaware, USA
| | - Stanley B. Prusiner
- Institute for Neurodegenerative Diseases and Department of Neurology, University of California, San Francisco, USA
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374
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Gadotti VM, Zamponi GW. Cellular prion protein protects from inflammatory and neuropathic pain. Mol Pain 2011; 7:59. [PMID: 21843375 PMCID: PMC3170224 DOI: 10.1186/1744-8069-7-59] [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: 07/08/2011] [Accepted: 08/16/2011] [Indexed: 11/30/2022] Open
Abstract
Cellular prion protein (PrPC) inhibits N-Methyl-D-Aspartate (NMDA) receptors. Since NMDA receptors play an important role in the transmission of pain signals in the dorsal horn of spinal cord, we thus wanted to determine if PrPC null mice show a reduced threshold for various pain behaviours. We compared nociceptive thresholds between wild type and PrPC null mice in models of inflammatory and neuropathic pain, in the presence and the absence of a NMDA receptor antagonist. 2-3 months old male PrPC null mice exhibited an MK-801 sensitive decrease in the paw withdrawal threshold in response both mechanical and thermal stimuli. PrPC null mice also exhibited significantly longer licking/biting time during both the first and second phases of formalin-induced inflammation of the paw, which was again prevented by treatment of the mice with MK-801, and responded more strongly to glutamate injection into the paw. Compared to wild type animals, PrPC null mice also exhibited a significantly greater nociceptive response (licking/biting) after intrathecal injection of NMDA. Sciatic nerve ligation resulted in MK-801 sensitive neuropathic pain in wild-type mice, but did not further augment the basal increase in pain behaviour observed in the null mice, suggesting that mice lacking PrPC may already be in a state of tonic central sensitization. Altogether, our data indicate that PrPC exerts a critical role in modulating nociceptive transmission at the spinal cord level, and fit with the concept of NMDA receptor hyperfunction in the absence of PrPC.
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Affiliation(s)
- Vinicius M Gadotti
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary T2N 4N1, Canada
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375
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Abstract
Microtubule-associated protein tau is the most commonly misfolded protein in human neurodegenerative diseases, where it becomes hyperphosphorylated and filamentous. Mutations in MAPT, the tau gene, cause approximately 5% of cases of frontotemporal dementia. They are frequently accompanied by parkinsonism. The existence of MAPT mutations has established that dysfunction of tau protein is sufficient to cause neurodegeneration and dementia. However, most tauopathies are not inherited in a dominant manner. The hyperphosphorylated sites are similar between diseases, but filament morphologies and tau isoform compositions vary. This is consistent with the existence of multiple tau conformers and recent findings have provided experimental support for this concept.
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376
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Johnson CJ, Bennett JP, Biro SM, Duque-Velasquez JC, Rodriguez CM, Bessen RA, Rocke TE. Degradation of the disease-associated prion protein by a serine protease from lichens. PLoS One 2011; 6:e19836. [PMID: 21589935 PMCID: PMC3092769 DOI: 10.1371/journal.pone.0019836] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 04/18/2011] [Indexed: 11/19/2022] Open
Abstract
The disease-associated prion protein (PrPTSE), the probable
etiological agent of the transmissible spongiform encephalopathies (TSEs), is
resistant to degradation and can persist in the environment. Lichens,
mutualistic symbioses containing fungi, algae, bacteria and occasionally
cyanobacteria, are ubiquitous in the environment and have evolved unique
biological activities allowing their survival in challenging ecological niches.
We investigated PrPTSE inactivation by lichens and found acetone
extracts of three lichen species (Parmelia sulcata,
Cladonia rangiferina and Lobaria
pulmonaria) have the ability to degrade prion protein (PrP) from
TSE-infected hamsters, mice and deer. Immunoblots measuring PrP levels and
protein misfolding cyclic amplification indicated at least two logs of
reductions in PrPTSE. Degradative activity was not found in closely
related lichen species or in algae or a cyanobacterium that inhabit lichens.
Degradation was blocked by Pefabloc SC, a serine protease inhibitor, but not
inhibitors of other proteases or enzymes. Additionally, we found that PrP levels
in PrPTSE-enriched preps or infected brain homogenates are also
reduced following exposure to freshly-collected P. sulcata or
an aqueous extract of the lichen. Our findings indicate that these lichen
extracts efficiently degrade PrPTSE and suggest that some lichens
could have potential to inactivate TSE infectivity on the landscape or be a
source for agents to degrade prions. Further work to clone and characterize the
protease, assess its effect on TSE infectivity and determine which organism or
organisms present in lichens produce or influence the protease activity is
warranted.
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Affiliation(s)
- Christopher J Johnson
- Prion Research Laboratory, United States Geological Survey National Wildlife Health Center, Madison, Wisconsin, United States of America.
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Stein KC, True HL. The [RNQ+] prion: a model of both functional and pathological amyloid. Prion 2011; 5. [PMID: 22052347 PMCID: PMC4012398 DOI: 10.4161/pri.5.4.18213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The formation of fibrillar amyloid is most often associated with protein conformational disorders such as prion diseases, Alzheimer disease and Huntington disease. Interestingly, however, an increasing number of studies suggest that amyloid structures can sometimes play a functional role in normal biology. Several proteins form self-propagating amyloids called prions in the budding yeast Saccharomyces cerevisiae. These unique elements operate by creating a reversible, epigenetic change in phenotype. While the function of the non-prion conformation of the Rnq1 protein is unclear, the prion form, [RNQ+], acts to facilitate the de novo formation of other prions to influence cellular phenotypes. The [RNQ+] prion itself does not adversely affect the growth of yeast, but the overexpression of Rnq1p can form toxic aggregated structures that are not necessarily prions. The [RNQ+] prion is also involved in dictating the aggregation and toxicity of polyglutamine proteins ectopically expressed in yeast. Thus, the [RNQ+] prion provides a tractable model that has the potential to reveal significant insight into the factors that dictate how amyloid structures are initiated and propagated in both physiological and pathological contexts.
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