101
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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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102
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Gunapala KM, Chang D, Hsu CT, Manaye K, Drenan RM, Switzer RC, Steele AD. Striatal pathology underlies prion infection-mediated hyperactivity in mice. Prion 2010; 4:302-15. [PMID: 20948312 DOI: 10.4161/pri.4.4.13721] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Although prion diseases are most commonly modeled using the laboratory mouse, the diversity of prion strains, behavioral testing and neuropathological assessments hamper our collective understanding of mouse models of prion disease. Here we compared several commonly used murine strains of prions in C57BL/6J female mice in a detailed home cage behavior detection system and a systematic study of pathological markers and neurotransmitter systems. We observed that mice inoculated with RML or 139A prions develop a severe hyperactivity phenotype in the home cage. A detailed assessment of pathology markers, such as microglial marker IBA1, astroglial marker GFAP and degeneration staining indicate early striatal pathology in mice inoculated with RML or 139A but not in those inoculated with 22L prions. An assessment of neuromodulatory systems including serotonin, dopamine, noradrenalin and acetylcholine showed surprisingly little decline in neuronal cell bodies or their innervations of regions controlling locomotor behavior, except for a small decrease in dopaminergic innervations of the dorsal striatum. These results implicate the dorsal striatum in mediating the major behavioral phenotype of 139A and RML prions. Further, they suggest that measurements of activity may be a sensitive manner in which to diagnose murine prion disease. With respect to neuropathology, our results indicate that pathological stains as opposed to neurotransmitter markers are much more informative and sensitive as markers of prion disease in mouse models.
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Affiliation(s)
- Keith M Gunapala
- Division of Biology, California Institute of Technology, Pasadena, CA, USA
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103
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Abstract
A shared neuropathological feature of idiopathic Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy is the development of intracellular aggregates of α-synuclein that gradually engage increasing parts of the nervous system. The pathogenetic mechanisms underlying these neurodegenerative disorders, however, are unknown. Several studies have highlighted similarities between classic prion diseases and these neurological proteinopathies. Specifically, identification of Lewy bodies in fetal mesencephalic neurons transplanted in patients with Parkinson's disease raised the hypothesis that α-synuclein, the main component of Lewy bodies, could be transmitted from the host brain to a graft of healthy neurons. These results and others have led to the hypothesis that a prion-like mechanism might underlie progression of synucleinopathy within the nervous system. We review experimental findings showing that misfolded α-synuclein can transfer between cells and, once transferred into a new cell, can act as a seed that recruits endogenous α-synuclein, leading to formation of larger aggregates. This model suggests that strategies aimed at prevention of cell-to-cell transfer of α-synuclein could retard progression of symptoms in Parkinson's disease and other synucleinopathies.
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Affiliation(s)
- Elodie Angot
- Wallenberg Neuroscience Centre, Lund University, Sweden
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104
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The hydrophobic core region governs mutant prion protein aggregation and intracellular retention. Biochem J 2010; 430:477-86. [DOI: 10.1042/bj20100615] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Approx. 15% of human prion diseases have a pattern of autosomal dominant inheritance, and are linked to mutations in the gene encoding PrP (prion protein), a GPI (glycosylphosphatidylinositol)-anchored protein whose function is not clear. The cellular mechanisms by which PrP mutations cause disease are also not known. Soon after synthesis in the ER (endoplasmic reticulum), several mutant PrPs misfold and become resistant to phospholipase cleavage of their GPI anchor. The biosynthetic maturation of the misfolded molecules in the ER is delayed and, during transit in the secretory pathway, they form detergent-insoluble and protease-resistant aggregates, suggesting that intracellular PrP aggregation may play a pathogenic role. We have investigated the consequence of deleting residues 114–121 within the hydrophobic core of PrP on the aggregation and cellular localization of two pathogenic mutants that accumulate in the ER and Golgi apparatus. Compared with their full-length counterparts, the deleted molecules formed smaller protease-sensitive aggregates and were more efficiently transported to the cell surface and released by phospholipase cleavage. These results indicate that mutant PrP aggregation and intracellular retention are closely related and depend critically on the integrity of the hydrophobic core. The discovery that Δ114–121 counteracts misfolding and improves the cellular trafficking of mutant PrP provides an unprecedented model for assessing the role of intracellular aggregation in the pathogenesis of prion diseases.
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105
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Cushman M, Johnson BS, King OD, Gitler AD, Shorter J. Prion-like disorders: blurring the divide between transmissibility and infectivity. J Cell Sci 2010; 123:1191-201. [PMID: 20356930 DOI: 10.1242/jcs.051672] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Prions are proteins that access self-templating amyloid forms, which confer phenotypic changes that can spread from individual to individual within or between species. These infectious phenotypes can be beneficial, as with yeast prions, or deleterious, as with mammalian prions that transmit spongiform encephalopathies. However, the ability to form self-templating amyloid is not unique to prion proteins. Diverse polypeptides that tend to populate intrinsically unfolded states also form self-templating amyloid conformers that are associated with devastating neurodegenerative disorders. Moreover, two RNA-binding proteins, FUS and TDP-43, which form cytoplasmic aggregates in amyotrophic lateral sclerosis, harbor a 'prion domain' similar to those found in several yeast prion proteins. Can these proteins and the neurodegenerative diseases to which they are linked become 'infectious' too? Here, we highlight advances that define the transmissibility of amyloid forms connected with Alzheimer's disease, Parkinson's disease and Huntington's disease. Collectively, these findings suggest that amyloid conformers can spread from cell to cell within the brains of afflicted individuals, thereby spreading the specific neurodegenerative phenotypes distinctive to the protein being converted to amyloid. Importantly, this transmissibility mandates a re-evaluation of emerging neuronal graft and stem-cell therapies. In this Commentary, we suggest how these treatments might be optimized to overcome the transmissible conformers that confer neurodegeneration.
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Affiliation(s)
- Mimi Cushman
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, 805b Stellar-Chance Laboratories, 422 Curie Boulevard, Philadelphia, PA 19104, USA
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106
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Abstract
Prions are responsible for a heterogeneous group of fatal neurodegenerative diseases. They occur in three forms - sporadic, genetic, or acquired - and involve non-covalent post-translational modifications of the cellular prion protein (PrPC). Prions (PrPSc) are characterized by their infectious properties and intrinsic ability to act as a template, converting the normal, physiological PrPC into the pathological form, PrPSc. The ‘protein-only’ hypothesis, postulated by Stanley B Prusiner, implies that the generation of de novo prions is possible. Exciting recent work, in vivo and in vitro, has further strengthened this postulate.
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Affiliation(s)
- Federico Benetti
- Laboratory of Prion Biology, Neurobiology Sector, Scuola Internazionale Superiore di Studi Avanzati - International School of Advanced Studies (SISSA-ISAS)via Bonomea 265, 34136 TriesteItaly
- Italian Institute of Technology, SISSA-ISAS Unitvia Bonomea 265, 34136 TriesteItaly
| | - Michael D Geschwind
- Memory and Aging Center, Department of Neurology, University of CaliforniaSan Francisco, Medical Center, Box 1207, San Francisco, CA 94117USA
| | - Giuseppe Legname
- Laboratory of Prion Biology, Neurobiology Sector, Scuola Internazionale Superiore di Studi Avanzati - International School of Advanced Studies (SISSA-ISAS)via Bonomea 265, 34136 TriesteItaly
- Italian Institute of Technology, SISSA-ISAS Unitvia Bonomea 265, 34136 TriesteItaly
- ELETTRA Laboratory, Sincrotrone Trieste S.C.p.A.S.S. 14 Km 163.5, 34012 Basovizza, TriesteItaly
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107
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Abstract
Prions are self-propagating proteinaceous infectious agents capable of transmitting disease in the absence of nucleic acids. The nature of the infectious agent in prion diseases has been at the center of passionate debate for the past 30 years. However, recent reports on the in vitro generation of prions have settled all doubts that the misfolded prion protein (PrP(Sc)) is the key component in propagating infectivity. However, we still do not understand completely the mechanism of prion replication and whether or not other cellular factors besides PrP(Sc) are required for infectivity. In this article, we discuss these recent reports under the context of the protein-only hypothesis and their implications.
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Affiliation(s)
- Rodrigo Diaz-Espinoza
- Mitchell Center for Alzheimer's disease and related brain disorders, Department of Neurology, The University of Texas Health Science Center, Houston, TX, USA
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108
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Colby DW, Giles K, Legname G, Wille H, Baskakov IV, DeArmond SJ, Prusiner SB. Design and construction of diverse mammalian prion strains. Proc Natl Acad Sci U S A 2009; 106:20417-22. [PMID: 19915150 PMCID: PMC2787151 DOI: 10.1073/pnas.0910350106] [Citation(s) in RCA: 169] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Indexed: 11/18/2022] Open
Abstract
Prions are infectious proteins that encipher biological information within their conformations; variations in these conformations dictate different prion strains. Toward elucidating the molecular language of prion protein (PrP) conformations, we produced an array of recombinant PrP amyloids with varying conformational stabilities. In mice, the most stable amyloids produced the most stable prion strains that exhibited the longest incubation times, whereas more labile amyloids generated less stable strains and shorter incubation times. The direct relationship between stability and incubation time of prion strains suggests that labile prions are more fit, in that they accumulate more rapidly and thus kill the host faster. Although incubation times can be changed by altering the PrP expression level, PrP sequence, prion dose, or route of inoculation, we report here the ability to modify the incubation time predictably in mice by modulating the prion conformation.
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Affiliation(s)
| | - Kurt Giles
- Institute for Neurodegenerative Diseases and
- Departments of Neurology and
| | - Giuseppe Legname
- Institute for Neurodegenerative Diseases and
- Departments of Neurology and
| | - Holger Wille
- Institute for Neurodegenerative Diseases and
- Departments of Neurology and
| | | | - Stephen J. DeArmond
- Institute for Neurodegenerative Diseases and
- Pathology, University of California, San Francisco, CA 94143
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109
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News updates. Lab Anim (NY) 2009. [DOI: 10.1038/laban1009-313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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110
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Whalley K. Proving the link. Nat Rev Neurosci 2009. [DOI: 10.1038/nrn2730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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