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Sirohi PR, Kumari A, Admane N, Somvanshi P, Grover A. The polyphenolic phytoalexin polydatin inhibits amyloid aggregation of recombinant human prion protein. RSC Adv 2021; 11:25901-25911. [PMID: 35479435 PMCID: PMC9037109 DOI: 10.1039/d1ra01891d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/22/2021] [Indexed: 12/01/2022] Open
Abstract
Prion diseases involve misfolded and highly infectious aggregates of prion protein (PrPSc) which forms amyloid plaques leading to fatal neurodegeneration. The absence of clinically proven therapeutics makes the discovery of effective remedial interventions a prime concern. Herein, we report novel prion intervention by the polyphenolic phytoalexin, polydatin which binds with moderate affinity to the recombinant protease resistant core of human prion protein, encompassing the sequence 90–231 (rPrPres) and inhibits its conversion into the highly neurotoxic forms. An extensive evaluation using biophysical techniques revealed that polydatin incubated rPrPres samples generate off-pathway oligomers having reduced cross-β sheet signature, and relatively smaller in size than the native rPrPres oligomers. The detailed structural analysis using molecular dynamics simulations elucidated the induction of antagonistic mobilities in the β2–α2 loop, α3 helix and the N-terminal amyloidogenic region of prions. This study puts forward novel prion fibrillogenesis inhibitory potential of polydatin, specifically by stabilizing the N-terminal amyloidogenic region. Collectively our results affirm the importance of polydatin in crippling the prion pathogenesis and may serve as a structural scaffold for designing novel therapeutic agents targeting amyloidogenic transition in prions. Polydatin is found to be a pharmacologically-significant scaffold that can bind to the rPrPres repertoire and inhibit its conversion to the highly infectious and neurotoxic PrPSc-like form, thus acting like a promising anti-prion drug lead.![]()
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Affiliation(s)
- Preeti Rana Sirohi
- School of Biotechnology
- Jawaharlal Nehru University
- New Delhi
- India
- Department of Biotechnology
| | - Anchala Kumari
- School of Biotechnology
- Jawaharlal Nehru University
- New Delhi
- India
| | - Nikita Admane
- School of Biotechnology
- Jawaharlal Nehru University
- New Delhi
- India
| | - Pallavi Somvanshi
- School of Computational and Integrative Sciences
- Jawaharlal Nehru University
- New Delhi
- India
- Special Centre of Systems Medicine
| | - Abhinav Grover
- School of Biotechnology
- Jawaharlal Nehru University
- New Delhi
- India
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Thellung S, Scoti B, Corsaro A, Villa V, Nizzari M, Gagliani MC, Porcile C, Russo C, Pagano A, Tacchetti C, Cortese K, Florio T. Pharmacological activation of autophagy favors the clearing of intracellular aggregates of misfolded prion protein peptide to prevent neuronal death. Cell Death Dis 2018; 9:166. [PMID: 29416016 PMCID: PMC5833808 DOI: 10.1038/s41419-017-0252-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/13/2017] [Accepted: 12/19/2017] [Indexed: 12/22/2022]
Abstract
According to the “gain-of-toxicity mechanism”, neuronal loss during cerebral proteinopathies is caused by accumulation of aggregation-prone conformers of misfolded cellular proteins, although it is still debated which aggregation state actually corresponds to the neurotoxic entity. Autophagy, originally described as a variant of programmed cell death, is now emerging as a crucial mechanism for cell survival in response to a variety of cell stressors, including nutrient deprivation, damage of cytoplasmic organelles, or accumulation of misfolded proteins. Impairment of autophagic flux in neurons often associates with neurodegeneration during cerebral amyloidosis, suggesting a role in clearing neurons from aggregation-prone misfolded proteins. Thus, autophagy may represent a target for innovative therapies. In this work, we show that alterations of autophagy progression occur in neurons following in vitro exposure to the amyloidogenic and neurotoxic prion protein-derived peptide PrP90-231. We report that the increase of autophagic flux represents a strategy adopted by neurons to survive the intracellular accumulation of misfolded PrP90-231. In particular, PrP90-231 internalization in A1 murine mesencephalic neurons occurs in acidic structures, showing electron microscopy hallmarks of autophagosomes and autophagolysosomes. However, these structures do not undergo resolution and accumulate in cytosol, suggesting that, in the presence of PrP90-231, autophagy is activated but its progression is impaired; the inability to clear PrP90-231 via autophagy induces cytotoxicity, causing impairment of lysosomal integrity and cytosolic diffusion of hydrolytic enzymes. Conversely, the induction of autophagy by pharmacological blockade of mTOR kinase or trophic factor deprivation restored autophagy resolution, reducing intracellular PrP90-231 accumulation and neuronal death. Taken together, these data indicate that PrP90-231 internalization induces an autophagic defensive response in A1 neurons, although incomplete and insufficient to grant survival; the pharmacological enhancement of this process exerts neuroprotection favoring the clearing of the internalized peptide and could represents a promising neuroprotective tool for neurodegenerative proteinopathies.
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Affiliation(s)
- Stefano Thellung
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Beatrice Scoti
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Alessandro Corsaro
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Valentina Villa
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Mario Nizzari
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy
| | - Maria Cristina Gagliani
- Section of Human Anatomy, Department of Experimental Medicine (DIMES), School of Medicine, University of Genova, Genova, Italy
| | - Carola Porcile
- Department of Health Sciences, University of Molise, Campobasso, Italy
| | - Claudio Russo
- Department of Health Sciences, University of Molise, Campobasso, Italy
| | - Aldo Pagano
- Section of Human Anatomy, Department of Experimental Medicine (DIMES), School of Medicine, University of Genova, Genova, Italy.,Ospedale Policlinico San Martino, IRCCS per l'Oncologia, Genova, Italy
| | - Carlo Tacchetti
- Centro Imaging Sperimentale, IRCCS Istituto Scientifico San Raffaele, Milano, Italy.,Vita-Salute San Raffaele University, Milano, Italy
| | - Katia Cortese
- Section of Human Anatomy, Department of Experimental Medicine (DIMES), School of Medicine, University of Genova, Genova, Italy
| | - Tullio Florio
- Section of Pharmacology, Department of Internal Medicine (DiMI), and Centre of Excellence for Biomedical Research (CEBR), University of Genova, Genova, Italy.
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Charco JM, Eraña H, Venegas V, García-Martínez S, López-Moreno R, González-Miranda E, Pérez-Castro MÁ, Castilla J. Recombinant PrP and Its Contribution to Research on Transmissible Spongiform Encephalopathies. Pathogens 2017; 6:E67. [PMID: 29240682 PMCID: PMC5750591 DOI: 10.3390/pathogens6040067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/08/2017] [Accepted: 12/12/2017] [Indexed: 01/13/2023] Open
Abstract
The misfolding of the cellular prion protein (PrPC) into the disease-associated isoform (PrPSc) and its accumulation as amyloid fibrils in the central nervous system is one of the central events in transmissible spongiform encephalopathies (TSEs). Due to the proteinaceous nature of the causal agent the molecular mechanisms of misfolding, interspecies transmission, neurotoxicity and strain phenomenon remain mostly ill-defined or unknown. Significant advances were made using in vivo and in cellula models, but the limitations of these, primarily due to their inherent complexity and the small amounts of PrPSc that can be obtained, gave rise to the necessity of new model systems. The production of recombinant PrP using E. coli and subsequent induction of misfolding to the aberrant isoform using different techniques paved the way for the development of cell-free systems that complement the previous models. The generation of the first infectious recombinant prion proteins with identical properties of brain-derived PrPSc increased the value of cell-free systems for research on TSEs. The versatility and ease of implementation of these models have made them invaluable for the study of the molecular mechanisms of prion formation and propagation, and have enabled improvements in diagnosis, high-throughput screening of putative anti-prion compounds and the design of novel therapeutic strategies. Here, we provide an overview of the resultant advances in the prion field due to the development of recombinant PrP and its use in cell-free systems.
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Affiliation(s)
- Jorge M. Charco
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
| | - Hasier Eraña
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
| | - Vanessa Venegas
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
| | - Sandra García-Martínez
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
| | - Rafael López-Moreno
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
| | - Ezequiel González-Miranda
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
| | - Miguel Ángel Pérez-Castro
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
| | - Joaquín Castilla
- CIC bioGUNE, Parque Tecnológico de Bizkaia, 48160 Derio, Spain; (J.M.C.); (H.E.); (V.V.); (S.G.-M.); (R.L.-M.); (E.G.-M.); (M.Á.P.-C.)
- IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
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Different Molecular Mechanisms Mediate Direct or Glia-Dependent Prion Protein Fragment 90-231 Neurotoxic Effects in Cerebellar Granule Neurons. Neurotox Res 2017; 32:381-397. [PMID: 28540665 DOI: 10.1007/s12640-017-9749-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 12/16/2022]
Abstract
Glia over-stimulation associates with amyloid deposition contributing to the progression of central nervous system neurodegenerative disorders. Here we analyze the molecular mechanisms mediating microglia-dependent neurotoxicity induced by prion protein (PrP)90-231, an amyloidogenic polypeptide corresponding to the protease-resistant portion of the pathological prion protein scrapie (PrPSc). PrP90-231 neurotoxicity is enhanced by the presence of microglia within neuronal culture, and associated to a rapid neuronal [Ca++] i increase. Indeed, while in "pure" cerebellar granule neuron cultures, PrP90-231 causes a delayed intracellular Ca++ entry mediated by the activation of NMDA receptors; when neuron and glia are co-cultured, a transient increase of [Ca++] i occurs within seconds after treatment in both granule neurons and glial cells, then followed by a delayed and sustained [Ca++] i raise, associated with the induction of the expression of inducible nitric oxide synthase and phagocytic NADPH oxidase. [Ca++] i fast increase in neurons is dependent on the activation of multiple pathways since it is not only inhibited by the blockade of voltage-gated channel activity and NMDA receptors but also prevented by the inhibition of nitric oxide and PGE2 release from glial cells. Thus, Ca++ homeostasis alteration, directly induced by PrP90-231 in cerebellar granule cells, requires the activation of NMDA receptors, but is greatly enhanced by soluble molecules released by activated glia. In glia-enriched cerebellar granule cultures, the activation of inducible nitric oxide (iNOS) and NADPH oxidase represents the main mechanism of toxicity since their pharmacological inhibition prevented PrP90-231 neurotoxicity, whereas NMDA blockade by D(-)-2-amino-5-phosphonopentanoic acid is ineffective; conversely, in pure cerebellar granule cultures, NMDA blockade but not iNOS inhibition strongly reduced PrP90-231 neurotoxicity. These data indicate that amyloidogenic peptides induce neurotoxic signals via both direct neuron interaction and glia activation through different mechanisms responsible of calcium homeostasis disruption in neurons and potentiating each other: the activation of excitotoxic pathways via NMDA receptors and the release of radical species that establish an oxidative milieu.
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Villa V, Thellung S, Bajetto A, Gatta E, Robello M, Novelli F, Tasso B, Tonelli M, Florio T. Novel celecoxib analogues inhibit glial production of prostaglandin E2, nitric oxide, and oxygen radicals reverting the neuroinflammatory responses induced by misfolded prion protein fragment 90-231 or lipopolysaccharide. Pharmacol Res 2016; 113:500-514. [PMID: 27667770 DOI: 10.1016/j.phrs.2016.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/05/2016] [Accepted: 09/12/2016] [Indexed: 12/24/2022]
Abstract
We tested the efficacy of novel cyclooxygenase 2 (COX-2) inhibitors in counteracting glia-driven neuroinflammation induced by the amyloidogenic prion protein fragment PrP90-231 or lipopolysaccharide (LPS). In search for molecules with higher efficacy than celecoxib, we focused our study on its 2,3-diaryl-1,3-thiazolidin-4-one analogues. As experimental models, we used the immortalized microglial cell line N9, rat purified microglial primary cultures, and mixed cultures of astrocytes and microglia. Microglia activation in response to PrP90-231 or LPS was characterized by growth arrest, morphology changes and the production of reactive oxygen species (ROS). Moreover, PrP90-231 treatment caused the overexpression of the inducible nitric oxide synthase (iNOS) and COX-2, with the consequent nitric oxide (NO), and prostaglandin E2 (PGE2) accumulation. These effects were challenged by different celecoxib analogues, among which Q22 (3-[4-(sulfamoyl)phenyl]-2-(4-tolyl)thiazolidin-4-one) inhibited microglia activation more efficiently than celecoxib, lowering both iNOS and COX-2 activity and reducing ROS release. During neurodegenerative diseases, neuroinflammation induced by amyloidogenic peptides causes the activation of both astrocytes and microglia with these cell populations mutually regulating each other. Thus the effects of PrP90-231 and LPS were also studied on mixed glial cultures containing astrocytes and microglia. PrP90-231 treatment elicited different responses in the co-cultures induced astrocyte proliferation and microglia growth arrest, resulting in a differential ability to release proinflammatory molecules with the production of NO and ROS mainly attributable on microglia, while COX-2 expression was induced also in astrocytes. Q22 effects on both NO and PGE2 secretion were more significant in the mixed glial cultures than in purified microglia, demonstrating Q22 ability to revert the functional interaction between astrocytes and microglia. These results demonstrate that Q22 is a powerful drug able to revert glial neuroinflammatory responses and might represent a lead to explore the chemical space around celecoxib frameworks to design even more effective agents, paving the way to novel approaches to contrast the neuroinflammation-dependent toxicity.
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Affiliation(s)
- Valentina Villa
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy
| | - Stefano Thellung
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy
| | - Adriana Bajetto
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy
| | - Elena Gatta
- Department of Physics, University of Genova, Genoa, Italy
| | - Mauro Robello
- Department of Physics, University of Genova, Genoa, Italy
| | - Federica Novelli
- Department of Pharmacy, University of Genova, 16132 Genoa, Italy
| | - Bruno Tasso
- Department of Pharmacy, University of Genova, 16132 Genoa, Italy
| | - Michele Tonelli
- Department of Pharmacy, University of Genova, 16132 Genoa, Italy
| | - Tullio Florio
- Laboratory of Pharmacology, Department of Internal Medicine, and Center of Excellence for Biomedical Research (CEBR), University of Genova, 16132 Genoa, Italy.
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Celecoxib Inhibits Prion Protein 90-231-Mediated Pro-inflammatory Responses in Microglial Cells. Mol Neurobiol 2014; 53:57-72. [PMID: 25404089 DOI: 10.1007/s12035-014-8982-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/03/2014] [Indexed: 12/21/2022]
Abstract
Activation of microglia is a central event in the atypical inflammatory response occurring during prion encephalopathies. We report that the prion protein fragment encompassing amino acids 90-231 (PrP90-231), a model of the neurotoxic activity of the pathogenic prion protein (PrP(Sc)), causes activation of both primary microglia cultures and N9 microglial cells in vitro. This effect was characterized by cell proliferation arrest and induction of a secretory phenotype, releasing prostaglandin E2 (PGE2) and nitric oxide (NO). Conditioned medium from PrP90-231-treated microglia induced in vitro cytotoxicity of A1 mesencephalic neurons, supporting the notion that soluble mediators released by activated microglia contributes to the neurodegeneration during prion diseases. The neuroinflammatory role of COX activity, and its potential targeting for anti-prion therapies, was tested measuring the effects of ketoprofen and celecoxib (preferential inhibitors of COX1 and COX2, respectively) on PrP90-231-induced microglial activation. Celecoxib, but not ketoprofen significantly reverted the growth arrest as well as NO and PGE2 secretion induced by PrP90-231, indicating that PrP90-231 pro-inflammatory response in microglia is mainly dependent on COX2 activation. Taken together, these data outline the importance of microglia in the neurotoxicity occurring during prion diseases and highlight the potentiality of COX2-selective inhibitors to revert microglia as adjunctive pharmacological approach to contrast the neuroinflammation-dependent neurotoxicity.
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Larda ST, Simonetti K, Al-Abdul-Wahid MS, Sharpe S, Prosser RS. Dynamic Equilibria between Monomeric and Oligomeric Misfolded States of the Mammalian Prion Protein Measured by 19F NMR. J Am Chem Soc 2013; 135:10533-41. [DOI: 10.1021/ja404584s] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Sacha Thierry Larda
- Department of Chemistry, University of Toronto, Toronto, Ontario,
Canada M5S 3H6
| | - Karen Simonetti
- Molecular
Structure and Function
Program, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | | | - Simon Sharpe
- Molecular
Structure and Function
Program, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
- Department of Biochemistry, University of Toronto, Toronto, Ontario,
Canada M5S 1A8
| | - R. Scott Prosser
- Department of Chemistry, University of Toronto, Toronto, Ontario,
Canada M5S 3H6
- Department of Biochemistry, University of Toronto, Toronto, Ontario,
Canada M5S 1A8
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Thellung S, Gatta E, Pellistri F, Corsaro A, Villa V, Vassalli M, Robello M, Florio T. Excitotoxicity through NMDA receptors mediates cerebellar granule neuron apoptosis induced by prion protein 90-231 fragment. Neurotox Res 2012; 23:301-14. [PMID: 22855343 DOI: 10.1007/s12640-012-9340-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/13/2012] [Accepted: 07/18/2012] [Indexed: 10/28/2022]
Abstract
Prion diseases recognize, as a unique molecular trait, the misfolding of CNS-enriched prion protein (PrP(C)) into an aberrant isoform (PrP(Sc)). In this work, we characterize the in vitro toxicity of amino-terminally truncated recombinant PrP fragment (amino acids 90-231, PrP90-231), on rat cerebellar granule neurons (CGN), focusing on glutamatergic receptor activation and Ca(2+) homeostasis impairment. This recombinant fragment assumes a toxic conformation (PrP90-231(TOX)) after controlled thermal denaturation (1 h at 53 °C) acquiring structural characteristics identified in PrP(Sc) (enrichment in β-structures, increased hydrophobicity, partial resistance to proteinase K, and aggregation in amyloid fibrils). By annexin-V binding assay, and evaluation of the percentage of fragmented and condensed nuclei, we show that treatment with PrP90-231(TOX), used in pre-fibrillar aggregation state, induces CGN apoptosis. This effect was associated with a delayed, but sustained elevation of [Ca(2+)]i. Both CGN apoptosis and [Ca(2+)]i increase were not observed using PrP90-231 in PrP(C)-like conformation. PrP90-231(TOX) effects were significantly reduced in the presence of ionotropic glutamate receptor antagonists. In particular, CGN apoptosis and [Ca(2+)]i increase were largely reduced, although not fully abolished, by pre-treatment with the NMDA antagonists APV and memantine, while the AMPA antagonist CNQX produced a lower, although still significant, effect. In conclusion, we report that CGN apoptosis induced by PrP90-231(TOX) correlates with a sustained elevation of [Ca(2+)]i mediated by the activation of NMDA and AMPA receptors.
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Affiliation(s)
- Stefano Thellung
- Department of Internal Medicine, Section of Pharmacology and Centre of Excellence for Biomedical Research (CEBR) School of Medicine, University of Genova, Viale Benedetto XV, 2, 16132, Genoa, Italy
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Role of prion protein aggregation in neurotoxicity. Int J Mol Sci 2012; 13:8648-8669. [PMID: 22942726 PMCID: PMC3430257 DOI: 10.3390/ijms13078648] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 06/29/2012] [Accepted: 07/02/2012] [Indexed: 11/17/2022] Open
Abstract
In several neurodegenerative diseases, such as Parkinson, Alzheimer’s, Huntington, and prion diseases, the deposition of aggregated misfolded proteins is believed to be responsible for the neurotoxicity that characterizes these diseases. Prion protein (PrP), the protein responsible of prion diseases, has been deeply studied for the peculiar feature of its misfolded oligomers that are able to propagate within affected brains, inducing the conversion of the natively folded PrP into the pathological conformation. In this review, we summarize the available experimental evidence concerning the relationship between aggregation status of misfolded PrP and neuronal death in the course of prion diseases. In particular, we describe the main findings resulting from the use of different synthetic (mainly PrP106-126) and recombinant PrP-derived peptides, as far as mechanisms of aggregation and amyloid formation, and how these different spatial conformations can affect neuronal death. In particular, most data support the involvement of non-fibrillar oligomers rather than actual amyloid fibers as the determinant of neuronal death.
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