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Loh D, Reiter RJ. Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27030705. [PMID: 35163973 PMCID: PMC8839844 DOI: 10.3390/molecules27030705] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/11/2022] [Accepted: 01/17/2022] [Indexed: 12/13/2022]
Abstract
The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
- Correspondence: (D.L.); (R.J.R.)
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health San Antonio, San Antonio, TX 78229, USA
- Correspondence: (D.L.); (R.J.R.)
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2
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Bertoli A, Sorgato MC. Neuronal pathophysiology featuring PrP C and its control over Ca 2+ metabolism. Prion 2018; 12:28-33. [PMID: 29227178 DOI: 10.1080/19336896.2017.1412912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Calcium (Ca2+) is an intracellular second messenger that ubiquitously masters remarkably diverse biological processes, including cell death. Growing evidence substantiates an involvement of the prion protein (PrPC) in regulating neuronal Ca2+ homeostasis, which could rationalize most of the wide range of functions ascribed to the protein. We have recently demonstrated that PrPC controls extracellular Ca2+ fluxes, and mitochondrial Ca2+ uptake, in neurons stimulated with glutamate (De Mario et al., J Cell Sci 2017; 130:2736-46), suggesting that PrPC protects neurons from threatening Ca2+ overloads and excitotoxicity. In light of these results and of recent reports in the literature, here we review the connection of PrPC with Ca2+ metabolism and also provide some speculative hints on the physiologic outcomes of this link. In addition, because PrPC is implicated in neurodegenerative diseases, including prion disorders and Alzheimer's disease, we will also discuss possible ways by which disruption of PrPC-Ca2+ association could be mechanistically connected with these pathologies.
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Affiliation(s)
- Alessandro Bertoli
- a Department of Biomedical Sciences , University of Padova , Padova , Italy.,b Padova Neuroscience Center , and University of Padova , Padova , Italy.,c CNR - Neuroscience Institute, University of Padova , Padova , Italy
| | - M Catia Sorgato
- a Department of Biomedical Sciences , University of Padova , Padova , Italy.,c CNR - Neuroscience Institute, University of Padova , Padova , Italy
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Shim SY, Karri S, Law S, Schatzl HM, Gilch S. Prion infection impairs lysosomal degradation capacity by interfering with rab7 membrane attachment in neuronal cells. Sci Rep 2016; 6:21658. [PMID: 26865414 PMCID: PMC4749993 DOI: 10.1038/srep21658] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/28/2016] [Indexed: 11/24/2022] Open
Abstract
Prions are proteinaceous infectious particles which cause fatal neurodegenerative disorders in humans and animals. They consist of a mostly β-sheeted aggregated isoform (PrPSc) of the cellular prion protein (PrPc). Prions replicate autocatalytically in neurons and other cell types by inducing conformational conversion of PrPc into PrPSc. Within neurons, PrPSc accumulates at the plasma membrane and in vesicles of the endocytic pathway. To better understand the mechanisms underlying neuronal dysfunction and death it is critical to know the impact of PrPSc accumulation on cellular pathways. We have investigated the effects of prion infection on endo-lysosomal transport. Our study demonstrates that prion infection interferes with rab7 membrane association. Consequently, lysosomal maturation and degradation are impaired. Our findings indicate a mechanism induced by prion infection that supports stable prion replication. We suggest modulation of endo-lysosomal vesicle trafficking and enhancement of lysosomal maturation as novel targets for the treatment of prion diseases.
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Affiliation(s)
- Su Yeon Shim
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Srinivasarao Karri
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Sampson Law
- Dept. of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Hermann M Schatzl
- Dept. of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Sabine Gilch
- Dept. of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
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Cholesterol balance in prion diseases and Alzheimer's disease. Viruses 2014; 6:4505-35. [PMID: 25419621 PMCID: PMC4246236 DOI: 10.3390/v6114505] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/08/2014] [Accepted: 11/14/2014] [Indexed: 12/16/2022] Open
Abstract
Prion diseases are transmissible and fatal neurodegenerative disorders of humans and animals. They are characterized by the accumulation of PrPSc, an aberrantly folded isoform of the cellular prion protein PrPC, in the brains of affected individuals. PrPC is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosyl-phosphatidyl-inositol (GPI) anchor. Specifically, it is associated with lipid rafts, membrane microdomains enriched in cholesterol and sphinoglipids. It has been established that inhibition of endogenous cholesterol synthesis disturbs lipid raft association of PrPC and prevents PrPSc accumulation in neuronal cells. Additionally, prion conversion is reduced upon interference with cellular cholesterol uptake, endosomal export, or complexation at the plasma membrane. Altogether, these results demonstrate on the one hand the importance of cholesterol for prion propagation. On the other hand, growing evidence suggests that prion infection modulates neuronal cholesterol metabolism. Similar results were reported in Alzheimer’s disease (AD): whereas amyloid β peptide formation is influenced by cellular cholesterol, levels of cholesterol in the brains of affected individuals increase during the clinical course of the disease. In this review, we summarize commonalities of alterations in cholesterol homeostasis and discuss consequences for neuronal function and therapy of prion diseases and AD.
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Silvius D, Pitstick R, Ahn M, Meishery D, Oehler A, Barsh GS, DeArmond SJ, Carlson GA, Gunn TM. Levels of the Mahogunin Ring Finger 1 E3 ubiquitin ligase do not influence prion disease. PLoS One 2013; 8:e55575. [PMID: 23383230 PMCID: PMC3559536 DOI: 10.1371/journal.pone.0055575] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 01/03/2013] [Indexed: 01/30/2023] Open
Abstract
Prion diseases are rare but invariably fatal neurodegenerative disorders. They are associated with spongiform encephalopathy, a histopathology characterized by the presence of large, membrane-bound vacuolar structures in the neuropil of the brain. While the primary cause is recognized as conversion of the normal form of prion protein (PrPC) to a conformationally distinct, pathogenic form (PrPSc), the cellular pathways and mechanisms that lead to spongiform change, neuronal dysfunction and death are not known. Mice lacking the Mahogunin Ring Finger 1 (MGRN1) E3 ubiquitin ligase develop spongiform encephalopathy by 9 months of age but do not become ill. In cell culture, PrP aberrantly present in the cytosol was reported to interact with and sequester MGRN1. This caused endo-lysosomal trafficking defects similar to those observed when Mgrn1 expression is knocked down, implicating disrupted MGRN1-dependent trafficking in the pathogenesis of prion disease. As these defects were rescued by over-expression of MGRN1, we investigated whether reduced or elevated Mgrn1 expression influences the onset, progression or pathology of disease in mice inoculated with PrPSc. No differences were observed, indicating that disruption of MGRN1-dependent pathways does not play a significant role in the pathogenesis of transmissible spongiform encephalopathy.
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Affiliation(s)
- Derek Silvius
- McLaughlin Research Institute, Great Falls, Montana, United States of America
| | - Rose Pitstick
- McLaughlin Research Institute, Great Falls, Montana, United States of America
| | - Misol Ahn
- Institute for Neurodegenerative Diseases and Department of Pathology, University of California San Francisco, San Francisco, California, United States of America
| | - Delisha Meishery
- McLaughlin Research Institute, Great Falls, Montana, United States of America
| | - Abby Oehler
- Institute for Neurodegenerative Diseases and Department of Pathology, University of California San Francisco, San Francisco, California, United States of America
| | - Gregory S. Barsh
- Departments of Genetics and Pediatrics, Stanford University, Stanford, California, United States of America
| | - Stephen J. DeArmond
- Institute for Neurodegenerative Diseases and Department of Pathology, University of California San Francisco, San Francisco, California, United States of America
| | - George A. Carlson
- McLaughlin Research Institute, Great Falls, Montana, United States of America
| | - Teresa M. Gunn
- McLaughlin Research Institute, Great Falls, Montana, United States of America
- * E-mail:
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Pradines E, Hernandez-Rapp J, Villa-Diaz A, Dakowski C, Ardila-Osorio H, Haik S, Schneider B, Launay JM, Kellermann O, Torres JM, Mouillet-Richard S. Pathogenic prions deviate PrP(C) signaling in neuronal cells and impair A-beta clearance. Cell Death Dis 2013; 4:e456. [PMID: 23303130 PMCID: PMC3563983 DOI: 10.1038/cddis.2012.195] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The subversion of the normal function exerted by the cellular prion protein (PrPC) in neurons by pathogenic prions is assumed to have a central role in the pathogenesis of transmissible spongiform encephalopathies. Using two murine models of prion infection, the 1C11 neuronal cell line and neurospheres, we document that prion infection is associated with the constitutive activation of signaling targets normally coupled with PrPC, including the Fyn kinase, the mitogen-associated protein kinases ERK1/2 and the CREB transcription factor. PrPC-dependent signaling overactivation in infected cells is associated with the recruitment of p38 and JNK stress-associated kinases. Downstream from CREB, prion-infected cells exhibit reduced activity of the matrix metalloprotease (MMP)-9. As MMP-9 catalyzes the degradation of the amyloid A-beta peptide, the decrease in MMP-9 activity in prion-infected cells causes a significant impairment of the clearance of A-beta, leading to its accumulation. By exploiting two 1C11-infected clones accumulating high or moderate levels of prions, we show that the prion-induced changes are correlated with the level of infectivity. Of note, a dose-dependent increase in A-beta levels was also found in the cerebrospinal fluid of mice inoculated with these infected clones. By demonstrating that pathogenic prions trigger increases in A-beta levels through the deviation of PrPC signaling, our data argue that A-beta may exacerbate prion-induced toxicity.
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Affiliation(s)
- E Pradines
- Cellules Souches, Signalisation et Prions, INSERM UMR-S747, 75006, Paris, France
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Santos TG, Beraldo FH, Hajj GNM, Lopes MH, Roffe M, Lupinacci FCS, Ostapchenko VG, Prado VF, Prado MAM, Martins VR. Laminin-γ1 chain and stress inducible protein 1 synergistically mediate PrPC-dependent axonal growth via Ca2+ mobilization in dorsal root ganglia neurons. J Neurochem 2012; 124:210-23. [PMID: 23145988 DOI: 10.1111/jnc.12091] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 11/01/2012] [Accepted: 11/01/2012] [Indexed: 12/01/2022]
Abstract
Prion protein (PrP(C)) is a cell surface glycoprotein that is abundantly expressed in nervous system. The elucidation of the PrP(C) interactome network and its significance on neural physiology is crucial to understanding neurodegenerative events associated with prion and Alzheimer's diseases. PrP(C) co-opts stress inducible protein 1/alpha7 nicotinic acetylcholine receptor (STI1/α7nAChR) or laminin/Type I metabotropic glutamate receptors (mGluR1/5) to modulate hippocampal neuronal survival and differentiation. However, potential cross-talk between these protein complexes and their role in peripheral neurons has never been addressed. To explore this issue, we investigated PrP(C)-mediated axonogenesis in peripheral neurons in response to STI1 and laminin-γ1 chain-derived peptide (Ln-γ1). STI1 and Ln-γ1 promoted robust axonogenesis in wild-type neurons, whereas no effect was observed in neurons from PrP(C) -null mice. PrP(C) binding to Ln-γ1 or STI1 led to an increase in intracellular Ca(2+) levels via distinct mechanisms: STI1 promoted extracellular Ca(2+) influx, and Ln-γ1 released calcium from intracellular stores. Both effects depend on phospholipase C activation, which is modulated by mGluR1/5 for Ln-γ1, but depends on, C-type transient receptor potential (TRPC) channels rather than α7nAChR for STI1. Treatment of neurons with suboptimal concentrations of both ligands led to synergistic actions on PrP(C)-mediated calcium response and axonogenesis. This effect was likely mediated by simultaneous binding of the two ligands to PrP(C). These results suggest a role for PrP(C) as an organizer of diverse multiprotein complexes, triggering specific signaling pathways and promoting axonogenesis in the peripheral nervous system.
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Affiliation(s)
- Tiago G Santos
- International Research Center, A.C. Camargo Hospital, São Paulo, Brazil
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Majer A, Medina SJ, Niu Y, Abrenica B, Manguiat KJ, Frost KL, Philipson CS, Sorensen DL, Booth SA. Early mechanisms of pathobiology are revealed by transcriptional temporal dynamics in hippocampal CA1 neurons of prion infected mice. PLoS Pathog 2012; 8:e1003002. [PMID: 23144617 PMCID: PMC3493483 DOI: 10.1371/journal.ppat.1003002] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 09/13/2012] [Indexed: 12/23/2022] Open
Abstract
Prion diseases typically have long pre-clinical incubation periods during which time the infectious prion particle and infectivity steadily propagate in the brain. Abnormal neuritic sprouting and synaptic deficits are apparent during pre-clinical disease, however, gross neuronal loss is not detected until the onset of the clinical phase. The molecular events that accompany early neuronal damage and ultimately conclude with neuronal death remain obscure. In this study, we used laser capture microdissection to isolate hippocampal CA1 neurons and determined their pre-clinical transcriptional response during infection. We found that gene expression within these neurons is dynamic and characterized by distinct phases of activity. We found that a major cluster of genes is altered during pre-clinical disease after which expression either returns to basal levels, or alternatively undergoes a direct reversal during clinical disease. Strikingly, we show that this cluster contains a signature highly reminiscent of synaptic N-methyl-D-aspartic acid (NMDA) receptor signaling and the activation of neuroprotective pathways. Additionally, genes involved in neuronal projection and dendrite development were also altered throughout the disease, culminating in a general decline of gene expression for synaptic proteins. Similarly, deregulated miRNAs such as miR-132-3p, miR-124a-3p, miR-16-5p, miR-26a-5p, miR-29a-3p and miR-140-5p follow concomitant patterns of expression. This is the first in depth genomic study describing the pre-clinical response of hippocampal neurons to early prion replication. Our findings suggest that prion replication results in the persistent stimulation of a programmed response that is mediated, at least in part, by synaptic NMDA receptor activity that initially promotes cell survival and neurite remodelling. However, this response is terminated prior to the onset of clinical symptoms in the infected hippocampus, seemingly pointing to a critical juncture in the disease. Manipulation of these early neuroprotective pathways may redress the balance between degeneration and survival, providing a potential inroad for treatment. Neurodegenerative diseases affect an ever-increasing proportion of the population; therefore, there is an urgent need to develop treatments. Prion disorders belong to this group of diseases and although rare and uniquely transmissible, share many features on a sub-cellular level. Central to disease is progressive synaptic impairment that invariably leads to the irreversible loss of neurons. Understanding this process is undoubtedly essential for rational drug discovery. In this study we looked at neurons very early in disease, when prions are barely detectable and there are no clinical symptoms observed. Specifically, we performed a comprehensive analysis of transcriptional changes within a particularly dense area of neurons, the CA1 hippocampus region, from prion-infected and control mice. In this way we were able to enrich our data for molecular changes unique to neurons and minimize those changes characteristic of support cells such as astrocytes and microglia. We detected the activation of a transcriptional program indicative of a protective mechanism within these neurons early in disease. This mechanism diminished as disease progressed and was lost altogether, concurrently with the onset of clinical symptoms. These findings demonstrate the ability of neurons to mount an initial neuroprotective response to prions that could be exploited for therapy development.
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Affiliation(s)
- Anna Majer
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Sarah J. Medina
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Yulian Niu
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Bernard Abrenica
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Kathy J. Manguiat
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Kathy L. Frost
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Clark S. Philipson
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Debra L. Sorensen
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Stephanie A. Booth
- Molecular PathoBiology, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Brambilla L, Martorana F, Rossi D. Astrocyte signaling and neurodegeneration: new insights into CNS disorders. Prion 2012; 7:28-36. [PMID: 23093800 DOI: 10.4161/pri.22512] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Growing evidence indicates that astrocytes cannot be just considered as passive supportive cells deputed to preserve neuronal activity and survival, but rather they are involved in a striking number of active functions that are critical to the performance of the central nervous system (CNS). As a consequence, it is becoming more and more evident that the peculiar properties of these cells can actively contribute to the extraordinary functional complexity of the brain and spinal cord. This new perception of the functioning of the CNS opens up a wide range of new possibilities to interpret various physiological and pathological events, and moves the focus beyond the neuronal compartment toward astrocyte-neuron interactions. With this in mind, here we provide a synopsis of the activities astrocytes perform in normal conditions, and we try to discuss what goes wrong with these cells in specific pathological conditions, such as Alzheimer Disease, prion diseases and amyotrophic lateral sclerosis.
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Affiliation(s)
- Liliana Brambilla
- Laboratory for Research on Neurodegenerative Disorders, IRCCS Fondazione Salvatore Maugeri, Pavia, Italy
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Abstract
Transmissible spongiform encephalopathies, or prion diseases, are lethal neurodegenerative disorders caused by the infectious agent named prion, whose main constituent is an aberrant conformational isoform of the cellular prion protein, PrP(C) . The mechanisms of prion-associated neurodegeneration and the physiologic function of PrP(C) are still unclear, although it is now increasingly acknowledged that PrP(C) plays a role in cell differentiation and survival. PrP(C) thus exhibits dichotomic attributes, as it can switch from a benign function under normal conditions to the triggering of neuronal death during disease. By reviewing data from models of prion infection and PrP-knockout paradigms, here we discuss the possibility that Ca(2+) is the hidden factor behind the multifaceted behavior of PrP(C) . By featuring in almost all processes of cell signaling, Ca(2+) might explain diverse aspects of PrP(C) pathophysiology, including the recently proposed one in which PrP(C) acts as a mediator of synaptic degeneration in Alzheimer's disease.
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Dearmond SJ, Bajsarowicz K. PrPSc accumulation in neuronal plasma membranes links Notch-1 activation to dendritic degeneration in prion diseases. Mol Neurodegener 2010; 5:6. [PMID: 20205843 PMCID: PMC2825502 DOI: 10.1186/1750-1326-5-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 01/21/2010] [Indexed: 11/25/2022] Open
Abstract
Prion diseases are disorders of protein conformation in which PrPC, the normal cellular conformer, is converted to an abnormal, protease-resistant conformer rPrPSc. Approximately 80% of rPrPSc accumulates in neuronal plasma membranes where it changes their physical properties and profoundly affects membrane functions. In this review we explain how rPrPSc is transported along axons to presynaptic boutons and how we envision the conversion of PrPC to rPrPSc in the postsynaptic membrane. This information is a prerequisite to the second half of this review in which we present evidence that rPrPSc accumulation in synaptic regions links Notch-1 signaling with the dendritic degeneration. The hypothesis that the Notch-1 intracellular domain, NICD, is involved in prion disease was tested by treating prion-infected mice with the γ-secretase inhibitor (GSI) LY411575, with quinacrine (Qa), and with the combination of GSI + Qa. Surprisingly, treatment with GSI alone markedly decreased NICD but did not prevent dendritic degeneration. Qa alone produced near normal dendritic trees. The combined GSI + Qa treatment resulted in a richer dendritic tree than in controls. We speculate that treatment with GSI alone inhibited both stimulators and inhibitors of dendritic growth. With the combined GSI + Qa treatment, Qa modulated the effect of GSI perhaps by destabilizing membrane rafts. GSI + Qa decreased PrPSc in the neocortex and the hippocampus by 95%, but only by 50% in the thalamus where disease was begun by intrathalamic inoculation of prions. The results of this study indicate that GSI + Qa work synergistically to prevent dendrite degeneration and to block formation of PrPSc.
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Affiliation(s)
- Stephen J Dearmond
- Department of Pathology, University of California San Francisco, 1855 Folsom Street MCB 269, San Francisco, CA 94143-0803, USA.
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Hwang D, Lee IY, Yoo H, Gehlenborg N, Cho JH, Petritis B, Baxter D, Pitstick R, Young R, Spicer D, Price ND, Hohmann JG, Dearmond SJ, Carlson GA, Hood LE. A systems approach to prion disease. Mol Syst Biol 2009; 5:252. [PMID: 19308092 PMCID: PMC2671916 DOI: 10.1038/msb.2009.10] [Citation(s) in RCA: 211] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 01/20/2009] [Indexed: 01/10/2023] Open
Abstract
Prions cause transmissible neurodegenerative diseases and replicate by conformational conversion of normal benign forms of prion protein (PrPC) to disease-causing PrPSc isoforms. A systems approach to disease postulates that disease arises from perturbation of biological networks in the relevant organ. We tracked global gene expression in the brains of eight distinct mouse strain–prion strain combinations throughout the progression of the disease to capture the effects of prion strain, host genetics, and PrP concentration on disease incubation time. Subtractive analyses exploiting various aspects of prion biology and infection identified a core of 333 differentially expressed genes (DEGs) that appeared central to prion disease. DEGs were mapped into functional pathways and networks reflecting defined neuropathological events and PrPSc replication and accumulation, enabling the identification of novel modules and modules that may be involved in genetic effects on incubation time and in prion strain specificity. Our systems analysis provides a comprehensive basis for developing models for prion replication and disease, and suggests some possible therapeutic approaches.
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Affiliation(s)
- Daehee Hwang
- Institute for Systems Biology, Seattle, WA 98103, USA
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13
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Sorgato MC, Bertoli A. From cell protection to death: May Ca2+ signals explain the chameleonic attributes of the mammalian prion protein? Biochem Biophys Res Commun 2009; 379:171-4. [DOI: 10.1016/j.bbrc.2008.12.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2008] [Accepted: 12/08/2008] [Indexed: 11/26/2022]
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14
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Jang B, Kim E, Choi JK, Jin JK, Kim JI, Ishigami A, Maruyama N, Carp RI, Kim YS, Choi EK. Accumulation of citrullinated proteins by up-regulated peptidylarginine deiminase 2 in brains of scrapie-infected mice: a possible role in pathogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1129-42. [PMID: 18787103 DOI: 10.2353/ajpath.2008.080388] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Peptidylarginine deiminases (PADs), which are a group of posttranslational modification enzymes, are involved in protein citrullination (deimination) by the conversion of peptidylarginine to peptidylcitrulline in a calcium concentration-dependent manner. Among the PADs, PAD2 is widely distributed in various tissues and is the only type that is expressed in brain. To elucidate the involvement of protein citrullination by PAD2 in the pathogenesis of brain-specific prion diseases, we examined the profiles of citrullinated proteins using the brains of scrapie-infected mice as a prion disease model. We found that, compared with controls, increased levels of citrullinated proteins of various molecular weights were detected in different brain sections of scrapie-infected mice. In support of this data, expression levels of PAD2 protein as well as its enzyme activity were significantly increased in brain sections of scrapie-infected mice, including hippocampus, brain stem, and striatum. Additionally, the expression levels of PAD2 mRNA were increased during scrapie infection. Moreover, PAD2 immunoreactivity was increased in scrapie-infected brains, with staining detected primarily in reactive astrocytes. Using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry, various citrullinated proteins were identified in the brains of scrapie-infected mice, including glial fibrillary acidic protein, myelin basic protein, enolases, and aldolases. This study suggests that accumulated citrullinated proteins and abnormal activation of PAD2 may function in the pathogenesis of prion diseases and serve as potential therapeutic targets.
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Affiliation(s)
- Byungki Jang
- Ilsong Institute of Life Science, Hallym University, Anyang, Republic of Korea
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Aguib Y, Gilch S, Krammer C, Ertmer A, Groschup MH, Schätzl HM. Neuroendocrine cultured cells counteract persistent prion infection by down-regulation of PrPc. Mol Cell Neurosci 2008; 38:98-109. [DOI: 10.1016/j.mcn.2008.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 01/30/2008] [Accepted: 02/13/2008] [Indexed: 11/25/2022] Open
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16
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Bedecs K. Cell culture models to unravel prion protein function and aberrancies in prion diseases. Methods Mol Biol 2008; 459:1-20. [PMID: 18576144 DOI: 10.1007/978-1-59745-234-2_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
From an early stage of prion research, tissue cultures that could support and propagate the scrapie agent were sought after. The earliest attempts were explants from brains of infected mice, and their growth and morphological characteristics were compared with those from uninfected mice. Using the explant technique, several investigators reported increased cell growth in cultures established from scrapie-sick brain compared with cultures from normal mice. These are odd findings in the light of the massive neuronal cell death known to occur in scrapie-infected brains; however, the cell types responsible for the increased cell growth in the scrapie-explants most probably were not neuronal. The first successful cell culture established in this way, in which the scrapie agent was serially and continuously passaged beyond the initial explant, was in the scrapie mouse brain culture, which is still used today. This chapter describes the generation and use of chronically prion-infected cell lines as cell culture models of prion diseases. These cell lines have been crucial for the current understanding of the cell biology of both the normal (PrP(C)) and the pathogenic isoform (PrP(Sc)) of the prion protein. They also have been useful in the development of antiprion drugs, prospectively used for therapy of prion diseases, and they offer an alternative approach for transmission/infectivity assays normally performed by mouse bioassay. Cell culture models also have been used to study prion-induced cytopathological changes, which could explain the typical spongiform neurodegeneration in prion diseases.
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Affiliation(s)
- Katarina Bedecs
- Department of Biochemistry and Biophysics, Stockholm University, Sweden
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17
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Abstract
The prion diseases result from the generation and propagation of an abnormal conformer of the prion protein. It is unclear how this molecular event disrupts neuronal function and viability. Current evidence argues it is not due to loss of normal prion protein activity or direct toxic effects of the abnormal conformer. Both the normal and abnormal prion proteins are glycosylphosphatidylinositol-linked membrane proteins. Conversion to the abnormal isoform results in the formation and accumulation of prion protein aggregates. Because aggregation of glycosylphosphatidylinositol-linked proteins activates Src-family kinases, the activation status and levels of the Src-family kinases in prion disease were investigated. Elevations of Src-family kinases were found in a cell culture model and two separate animal models of prion disease. The elevations in Src kinases preceded the onset of symptoms and occurred concurrently with the appearance of detergent-insoluble prion protein. In addition, the total level of kinases phosphorylated at tyrosine residues associated with activation was increased. Similar alterations were not present in brain homogenates from presymptomatic animals early in the disease course, prion protein-ablated animals, or end-stage Tg2576 mice overexpressing mutant amyloid precursor protein. Identification of similar elevations in cell culture and animal model systems suggests the elevations are a specific response to the presence of the disease-associated conformer. Abnormal regulation of these signal transduction cascades may be a key element in the cellular pathology of the prion diseases.
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Affiliation(s)
- Randal R Nixon
- Department of Pathology, Oregon Health & Sciences University, Portland, Oregon 97201, USA
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Russelakis-Carneiro M, Hetz C, Maundrell K, Soto C. Prion replication alters the distribution of synaptophysin and caveolin 1 in neuronal lipid rafts. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 165:1839-48. [PMID: 15509552 PMCID: PMC1618653 DOI: 10.1016/s0002-9440(10)63439-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The main event in the pathogenesis of prion diseases is the conversion of the cellular prion protein (PrP(C)) into the abnormal, protease-resistant prion protein (PrP(res)). PrP(C) is a GPI-anchored protein located in lipid rafts or detergent-resistant membranes (DRMs). Here we describe the association of PrP with DRMs in neuronal cell bodies and axons during the course of murine scrapie and its relation with the distribution of the PrP-interacting proteins caveolin 1 and synaptophysin. Scrapie infection triggered the accumulation of PrP(res) in DRMs from retinas and optic nerves from early stages of the disease before evidence of neuronal cell loss. Most of the PrP(res) remained associated with lipid rafts throughout different stages in disease progression. In contrast to PrP(res), caveolin 1 and synaptophysin in retina and optic nerves shifted to non-DRM fractions during the course of scrapie infection. The accumulation of PrP(res) in DRMs was not associated with a general alteration in their composition, because no change in the total protein distribution across the sucrose gradient or in the flotation characteristics of the glycosphingolipid GM1 or Thy-1 were observed until advanced stages of the disease. However, an increase in total cholesterol levels was observed in optic nerve and retinas. Only during late stages of the disease was a decrease in the number of neuronal cell bodies observed, suggesting that synaptic abnormalities are the earliest sign of neuronal dysfunction that ultimately results in neuronal death. These results indicate that prion replication triggers an abnormal localization of caveolin 1 and synaptophysin, which in turn may alter neuronal function.
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19
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Bouzamondo-Bernstein E, Hopkins SD, Spilman P, Uyehara-Lock J, Deering C, Safar J, Prusiner SB, Ralston HJ, DeArmond SJ. The neurodegeneration sequence in prion diseases: evidence from functional, morphological and ultrastructural studies of the GABAergic system. J Neuropathol Exp Neurol 2004; 63:882-99. [PMID: 15330342 DOI: 10.1093/jnen/63.8.882] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Loss of the GABAergic system of neurons has been reported to be the first detectable neuropathological change in prion diseases, which features the accumulation of an aberrant isoform of the prion protein (PrP(Sc)). To determine the timing of GABAergic system dysfunction and degeneration and its relationship to PrP(Sc) accumulation during the course of prion disease in Syrian hamsters, we applied 3 approaches: i) quantifying GABA-immunopositive neurons and their processes by light and electron microscopy to test for selective loss; ii) measuring evoked [3H]-GABA release from synaptosomes to test for functional abnormalities; and iii) determining the kinetics of PrP(Sc) accumulation in subcellular fractions to correlate it with GABAergic dysfunction. At the terminal stages of disease, we found a significant increase in the number of GABA-positive and -negative presynaptic boutons with abnormally aggregated synaptic vesicles. At the same stage, we also found an equal degree of GABA-immunopositive and -immunonegative presynaptic bouton loss. In contrast, GABA-positive neocortical cell bodies increased, based on stereologic estimates in the terminal stage of scrapie. In the context of these abnormalities, evoked release of [3H]-GABA from cortical and thalamic synaptosomes was significantly decreased, which correlated well with the accumulation of PrP(Sc) in synaptosomes and cell membrane fractions.
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Affiliation(s)
- Essia Bouzamondo-Bernstein
- Institute for Neurodegenerative Diseases, and Department of Pathology, University of California San Francisco, San Francisco, California, USA
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20
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Szabó R, Hudecz F, Reig F. Interfacial interactions between poly[L-lysine]-based branched polypeptides and phospholipid model membranes. J Colloid Interface Sci 2004; 267:18-24. [PMID: 14554162 DOI: 10.1016/s0021-9797(03)00604-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The interaction of five poly[L-lysine]-derived branched chain polypeptides of poly[Lys(X(i))] (X(i)K) or poly[Lys(X(i)-DL-Ala(m))] (XAK) with lipid bilayers (DPPC and DPPC/PG, 8:2) was studied by fluorescence polarization techniques. Two fluorescent probes, DPH and TMA-DPH, were utilized to monitor changes of motion in the internal and/or in the polar head regions, respectively. Results indicate that the interaction of polypeptides with neutral (DPPC) bilayers is mainly dependent on the polarity and electrical charge of side chains. The amphoteric E(i)K shows the highest level of interaction. Polycationic polypeptides (H(i)K, P(i)K, TAK) have a relatively small effect on the transition temperature of the lipids, while the polyanionic Succ-EAK has no effect at the alkyl chain region of the bilayer. Data with TMA-DPH indicate the lack of pronounced interaction between the polypeptides and the outer surface of the liposome. Similar tendency was documented for DPPC/PG vesicles. Polypeptides, H(i)K, and P(i)K induce significant changes in the transition temperature, thus indicating their insertion into the hydrophobic core of the bilayer without marked effect on the polar head region. Results suggest that these polypeptides (except E(i)K) have no destabilizing effect on liposomes studied. These properties are considered as beneficial for their use as safe carriers for bioactive molecules.
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Affiliation(s)
- R Szabó
- Research Group Peptide Chemistry at Eötvös L. University, Hungarian Academy of Sciences, P.O. Box 32, H-1518 Budapest 112, Hungary
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21
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Sandberg MK, Wallén P, Wikström MA, Kristensson K. Scrapie-infected GT1-1 cells show impaired function of voltage-gated N-type calcium channels (Cav 2.2) which is ameliorated by quinacrine treatment. Neurobiol Dis 2004; 15:143-51. [PMID: 14751779 DOI: 10.1016/j.nbd.2003.09.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Prions are transmissible pathogens that cause neurodegenerative diseases, although the mechanisms behind the nervous system dysfunctions are unclear. To study the effects of a prion infection on voltage-gated calcium channels, scrapie-infected gonadotropin-releasing hormone neuronal cells (ScGT1-1) in culture were depolarized by KCl and calcium responses recorded. Lower calcium responses were observed in infected compared to uninfected cells. This effect was still observed when L-type calcium channels were blocked by nimodipine. After inhibition of N-type calcium channels with omega-conotoxin GVIA, there was no difference in calcium responses. The calcium responses after nimodipine treatment became progressively lower during infection, but there was no major loss of the cellular prion protein (PrP(C)) or marked increase in accumulation of the abnormal prion protein (PrP(Sc)) in the cultures. These results indicate that scrapie infection causes a dysfunction of voltage-gated N-type calcium channels, which is exacerbated slowly over time. Quinacrine treatment cleared PrP(Sc) and restored calcium responses in the ScGT1-1 cultures.
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Affiliation(s)
- Malin K Sandberg
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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22
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Vassallo N, Herms J. Cellular prion protein function in copper homeostasis and redox signalling at the synapse. J Neurochem 2003; 86:538-44. [PMID: 12859667 DOI: 10.1046/j.1471-4159.2003.01882.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The fundamental physiological function of native cellular prion (PrPC) remains unknown. Herein, the most salient observations as regards prion physiology are critically evaluated. These include: (i) the role of PrPC in copper homeostasis, particularly at the pre-synaptic membrane; (ii) involvement of PrPC in neuronal calcium disturbances; and (iii) the neuroprotective properties of PrPC in response to copper and oxidative stress. Ultimately, a tentative hypothesis of basic prion function is derived, namely that PrPC acts as a sensor for copper and/or free radical stimuli, thereby triggering intracellular calcium signals that finally translate into modulation of synaptic transmission and maintenance of neuronal integrity.
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Affiliation(s)
- Neville Vassallo
- Department of Physiology and Biochemistry, University of Malta, Msida, Germany
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23
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DeArmond SJ, Prusiner SB. Perspectives on prion biology, prion disease pathogenesis, and pharmacologic approaches to treatment. Clin Lab Med 2003; 23:1-41. [PMID: 12733423 DOI: 10.1016/s0272-2712(02)00041-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The main goals of this article have been to summarize our current understanding of the biology of PrP, the propagation of prions, and the etiology and pathogenesis of each form of prion disease (familial, sporadic, and infectious); and to review current rational pharmacologic strategies for treatment of prion diseases. Each of these subjects is presented primarily from the perspective of investigations performed by the prion disease research laboratories at the University of California in San Francisco and by its many collaborators in the United States and abroad. This review focuses on key results from the hundreds of transgenic mouse lines expressing different PrP constructs that have been used to determine the roles played by different PrPSc and PrPC domains in prion propagation and the prion disease phenotype.
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Affiliation(s)
- Stephen J DeArmond
- Department of Pathology (Neuropathology Unit), Institute for Neurodegenerative Diseases, University of California, 513 Parnassus Avenue, San Francisco, CA, USA.
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24
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Lindegren H, Ostlund P, Gyllberg H, Bedecs K. Loss of lipopolysaccharide-induced nitric oxide production and inducible nitric oxide synthase expression in scrapie-infected N2a cells. J Neurosci Res 2003; 71:291-9. [PMID: 12503093 DOI: 10.1002/jnr.10473] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In scrapie-infected cells, the conversion of the cellular prion protein to the pathogenic prion has been shown to occur in lipid rafts, which are suggested to function as signal transduction platforms. Neuronal cells may respond to bacterial lipopolysaccharide (LPS) treatment with a sustained and elevated nitric oxide (NO) release. Because prions and the major LPS receptor CD14 are colocalized in lipid rafts, the LPS-induced NO production in scrapie-infected neuroblastoma cells was studied. This study shows that LPS induces a dose- and time-dependent increase in NO release in the murine neuroblastoma cell line N2a, with a 50-fold increase in NO production at 1 microg/ml LPS after 96 hr, as measured by nitrite in the medium. This massive NO release was not caused by activation of the neuronal NO synthase (nNOS), but by increased expression of the inducible NOS (iNOS) mRNA and protein. However, in scrapie-infected N2a cells (ScN2a), the LPS-induced NO production was completely abolished. The absence of LPS-induced NO production in ScN2a was due not to abolished enzymatic activity of iNOS but to a complete inhibition of the LPS-induced iNOS gene expression as measured by Western blot and RT-PCR. These results indicate that scrapie infection inhibits the LPS-mediated signal transduction upstream of the transcriptional step in the signaling cascade and may reflect the important molecular and cellular changes induced by scrapie infection.
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Affiliation(s)
- Heléne Lindegren
- Department of Neurochemistry and Neurotoxicology, University of Stockholm, Stockholm, Sweden
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25
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Abstract
Cell cultures represent relevant and useful experimental models of transmissible spongiform encephalopathies (TSEs). They are able to promote, upon subpassaging, stable and persistent replication of PrP(Sc) as well as infectivity. To date, only a few cell culture models permissive to prion replication are available. Among them, mouse neuroblastoma cell lines (N2a) are most commonly used. While they correspond to homologous models supporting propagation of mouse-adapted scrapie strains, recent studies have reported heterologous models sensitive to natural occurring disease. Infected cell culture models have provided some valuable insights into the biogenesis of PrP(Sc) in terms of conversion, subcellular localisations, physiopathological consequences and species-barrier determinants. They have also contributed to the screening and the study of possible therapeutic compounds and to the development of new strategies for the investigation of TSE-specific diagnostic markers.
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Affiliation(s)
- Jérôme Solassol
- Institut de Génétique Humaine, CNRS UPR 1142, Montpellier, France
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26
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Kourie JI, Henry CL. Ion channel formation and membrane-linked pathologies of misfolded hydrophobic proteins: the role of dangerous unchaperoned molecules. Clin Exp Pharmacol Physiol 2002; 29:741-53. [PMID: 12165037 DOI: 10.1046/j.1440-1681.2002.03737.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Protein-membrane interaction includes the interaction of proteins with intrinsic receptors and ion transport pathways and with membrane lipids. Several hypothetical interaction models have been reported for peptide-induced membrane destabilization, including hydrophobic clustering, electrostatic interaction, electrostatic followed by hydrophobic interaction, wedge x type incorporation and hydrophobic mismatch. 2. The present review focuses on the hypothesis of protein interaction with lipid membranes of those unchaperoned positively charged and misfolded proteins that have hydrophobic regions. We advance the hypothesis that protein misfolding that leads to the exposure of hydrophobic regions of proteins renders them potentially cytotoxic. Such proteins include prion, amyloid beta protein (AbetaP), amylin, calcitonin, serum amyloid and C-type natriuretic peptides. These proteins have the ability to interact with lipid membranes, thereby inducing membrane damage and cell malfunction. 3. We propose that the most significant mechanism of membrane damage induced by hydrophobic misfolded proteins is mediated via the formation of ion channels. The hydrophobicity based toxicity of several proteins linked to neurodegenerative pathologies is similar to those observed for antibacterial toxins and viral proteins. 4. It is hypothesized that the membrane damage induced by amyloids, antibacterial toxins and viral proteins represents a common mechanism for cell malfunction, which underlies the associated pathologies and cytotoxicity of such proteins.
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Affiliation(s)
- Joseph I Kourie
- Membrane Transport Group, Department of Chemistry, The Faculties, The Australian National University, Science Road, Canberra, ACT 0200, Australia. joseph.kourie@@anu.edu.au
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27
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Harris DA. Biosynthesis and cellular processing of the prion protein. ADVANCES IN PROTEIN CHEMISTRY 2002; 57:203-28. [PMID: 11447691 DOI: 10.1016/s0065-3233(01)57023-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- D A Harris
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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28
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Kellermann O, Lafay-Chebassier C, Ermonval M, Lehmann S, Mouillet-Richard S. From stem cells to prion signalling. C R Biol 2002; 325:9-15. [PMID: 11862626 DOI: 10.1016/s1631-0691(02)01387-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
A strategy based upon the introduction of an adenovirus-SV40 plasmid into multipotential cells was designed to immortalize clones displaying properties of lineage stem cells. The murine 1C11 cell line behaves as a neuroepithelial progenitor. Upon appropriate induction, almost 100% of 1C11 precursor cells develop neurite extensions and convert into either serotonergic or noradrenergic neurons. The two mutually exclusive neuronal programs are autoregulated by serotonergic or adrenergic receptors. PrPc is constitutively expressed by 1C11 cells. Antibody-mediated cross-linking of PrPc promotes the dephosphorylation of the tyrosine kinase Fyn associated to a Fyn kinase activation. The coupling of PrPc to Fyn is dependent on caveolin-1. It is restricted to the fully differentiated serotonergic or noradrenergic cells and occurs mainly at neurites. Thus, PrPc may represent a signal transduction protein which may fine-tune neuronal functions. Since the 1C11 stem cell supports prion replication, it may provide a tool to investigate whether PrPSc accumulation interferes with PrPc signalling activity.
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Affiliation(s)
- Odile Kellermann
- Laboratoire de différenciation cellulaire et prions, CNRS UPR 1983-Institut Pasteur, BP 8, 94801 Villejuif, France.
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29
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Ostlund P, Lindegren H, Pettersson C, Bedecs K. Altered insulin receptor processing and function in scrapie-infected neuroblastoma cell lines. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 97:161-70. [PMID: 11750072 DOI: 10.1016/s0169-328x(01)00316-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The underlying neurochemical changes contributing to prion-induced neurodegeneration remain largely unknown. This study shows that scrapie infection induced a 2-fold increase of insulin receptor (IR) protein and aberrantly processed IR beta-chain in scrapie-infected N2a neuroblastoma cells (ScN2a) as measured by Western blot of immunoprecipitated IR, in the absence of increased IR mRNA. Elevated IR protein level was further confirmed in an independently scrapie-infected neuroblastoma cell line N1E-115 (ScN1E-115). Proliferation studies showed that the increased IR level in ScN2a did not result in an increased insulin-mediated cell growth compared to normal N2a cells. Binding studies indicated that this apparent paradox was due to a 65% decrease in specific [(125)I]insulin binding sites in ScN2a when compared to the amount of immunoreactive IR, although the IR binding affinity was unchanged. Analysis of insulin stimulated IR tyrosine phosphorylation showed a slight but not significant reduction in ScN2a, when related to the increased level of immunoreactive IR. However, comparing the IR tyrosine phosphorylation to the loss of binding sites in ScN2a, we demonstrated an increased IR tyrosine phosphorylation of the remaining functional IR. In addition to these differences in IR properties, the basal extracellular signal regulated kinase-2 (ERK2) phosphorylation detected by Western blot, was significantly elevated and the insulin stimulated ERK2 phosphorylation was subsequently decreased in ScN2a. Together, these data show that scrapie infection affects the level and processing of the IR and signal transduction mediated by the IR in neuroblastoma cells, as well as induces an elevated basal ERK2 phosphorylation. Aberrant regulation of neuroprotective receptors may contribute to neurodegeneration in prion diseases.
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Affiliation(s)
- P Ostlund
- Department of Neurochemistry and Neurotoxicology, University of Stockholm, Svante Arrhenius v. 21A, S-10691 Stockholm, Sweden
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30
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Kourie JI. Mechanisms of prion-induced modifications in membrane transport properties: implications for signal transduction and neurotoxicity. Chem Biol Interact 2001; 138:1-26. [PMID: 11640912 DOI: 10.1016/s0009-2797(01)00228-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Prion-related encephalopathies are associated with the conversion of a normal cellular isoform of prion protein (PrP(c)) to an abnormal pathologic scrapie isoform (PrP(Sc)). The conversion of this single polypeptide chain involves a reduction in the alpha-helices and an increase in beta-sheet content. This change in the content ratio of alpha-helices to beta-sheets may explain the diversity in the proposed mechanisms of action. Many of the pathogenic properties of PrP(Sc), such as neurotoxicity, proteinase-resistant properties and induction of hypertrophy and proliferation of astrocytes, have been attributed to the peptide fragment corresponding to residues 106-126 of prion (PrP[106-126]). In particular, the amyloidogenic and hydrophobic core AGAAAAGA has been implicated in modulation of neurotoxicity and the secondary structure of PrP[106-126]. Because of some similarities between the properties of PrP[106-126] and PrP(Sc), the former is used as a useful tool to characterize the pharmacological and biophysical properties of PrP(Sc) in general and of that domain in particular, by various laboratories. However, it is important to note that by no means can PrP[106-126] be considered a complete equivalent to PrP(Sc) in function. Several hypotheses have been proposed to explain prion-induced neurodegenerative diseases. These non-exclusive hypotheses include: (i) changes in the membrane microviscosity; (ii) changes in the intracellular Ca(2+) homeostasis; (iii) superoxide dismutase and Cu(2+) homeostasis; and (iv) changes in the immune system. The prion-induced modification in Ca(2+) homeostasis is the result of: (1) prion interaction with intrinsic ion transport proteins, e.g. L-type Ca(2+) channels in the surface membrane, and IP(3)-modulated Ca(2+) channels in the internal membranes, and/or (2) formation of cation channels. These two mechanisms of action lead to changes in Ca(2+) homeostasis that further augment the abnormal electrical activity and the distortion of signal transduction causing cell death. It is concluded that the hypothesis of the interaction of PrP[106-126] with membranes and formation of redox-sensitive and pH-modulated heterogeneous ion channels is consistent with: (a) PrP-induced changes in membrane fluidity and viscosity; (b) PrP-induced changes in Ca(2+) homeostasis (and does not exclude changes in endogenous Ca(2+) transport pathways and Cu(2+) homeostasis); (c) PrP role as an antioxidant; and (d) the PrP structural properties, i.e. beta sheets, protein aggregation, hydrophobicity, functional significance of specific amino acids (e.g. methionine, histidine) and regulation with low pH.
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Affiliation(s)
- J I Kourie
- Membrane Transport Group, Department of Chemistry, The Faculties, The Australian National University, ACT, 0200, Canberra, Australia.
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31
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Head MW, Farquhar CF, Mabbott NA, Fraser JR. The transmissible spongiform encephalopathies: pathogenic mechanisms and strategies for therapeutic intervention. Expert Opin Ther Targets 2001; 5:569-585. [PMID: 12540284 DOI: 10.1517/14728222.5.5.569] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Primary neurodegenerative diseases tend to be intractable and largely affect the elderly. There is rarely the opportunity to identify individuals at risk and the appearance of clinical symptoms usually signifies the occurrence of irreversible neurological damage. This situation describes sporadic Creutzfeldt-Jakob disease which occurs world-wide, affecting one person per million per annum. The epidemic of bovine spongiform encephalopathy in the UK in the 1980s and the subsequent causal appearance of variant Creutzfeldt-Jakob disease in young UK residents in the 1990s has refocused attention on this whole group of diseases, known as the transmissible spongiform encephalopathies or prion diseases. The potentially lengthy incubation period of variant Creutzfeldt-Jakob disease, including perhaps an obligate peripheral phase, prior to neuroinvasion, marks variant Creutzfeldt-Jakob disease out as different from sporadic Creutzfeldt-Jakob disease. The formal possibility of detecting individuals infected with the bovine spongiform encephalopathy agent during this asymptomatic peripheral phase provides a strong incentive for the development of therapies for transmissible spongiform encephalopathies. This review focuses on recent advances in the understanding of the pathogenesis of these diseases, with particular reference to in vitro and animal model systems. Such systems have proved invaluable in the identification of potential therapeutic strategies that either specifically target the prion protein or more generally target peripheral pathogenesis. Furthermore, recent experiments in animal models suggest that even after neuroinvasion there may be pharmacological avenues to explore that might retard or even halt the degenerative process.
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Affiliation(s)
- Mark W Head
- National Creutzfeldt-Jakob Disease Surveillance Unit and Department of Pathology of Edinburgh University, Western General Hospital, Edinburgh, EH4 2XU, UK.
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32
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Abstract
A great deal of effort has been devoted during the past 20 years to defining the chemical nature of prions, the infectious agents responsible for transmissible spongiform encephalopathies. In contrast, much less attention has been paid to elucidating how prions actually damage the central nervous system. Although it is commonly assumed that PrP(Sc), the protein constituent of infectious prions, is the primary culprit, increasing evidence indicates that this may not be the case. Several alternative molecular forms of PrP are reasonable candidates for the neurotoxic species in prion diseases, although it is still too early to tell whether these or other ones will turn out to be the true instigating factors. The cellular pathways activated by neurotoxic forms of PrP that ultimately result in neuronal death are also being investigated, and several possible mechanisms have been uncovered, including the operation of quality control processes in the endoplasmic reticulum. Elucidating the distinction between the infectious and neurotoxic forms of PrP has important implications for designing therapy of prion diseases, as well as for understanding pathogenic mechanisms operative in other neurodegenerative disorders and the role of prion-like states in biology.
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Affiliation(s)
- R Chiesa
- Istituto di Ricerche Farmacologiche Mario Negri, Milano, 20157, Italy
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33
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Ostlund P, Lindegren H, Pettersson C, Bedecs K. Up-regulation of functionally impaired insulin-like growth factor-1 receptor in scrapie-infected neuroblastoma cells. J Biol Chem 2001; 276:36110-5. [PMID: 11461928 DOI: 10.1074/jbc.m105710200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A growing body of evidence suggests that an altered level or function of the neurotrophic insulin-like growth factor-1 receptor (IGF-1R), which supports neuronal survival, may underlie neurodegeneration. This study has focused on the expression and function of the IGF-1R in scrapie-infected neuroblastoma cell lines. Our results show that scrapie infection induces a 4-fold increase in the level of IGF-1R in two independently scrapie-infected neuroblastomas, ScN2a and ScN1E-115 cells, and that the increased IGF-1R level was accompanied by increased IGF-1R mRNA levels. In contrast to the elevated IGF-1R expression in ScN2a, receptor binding studies revealed an 80% decrease in specific (125)I-IGF-1-binding sites compared with N2a cells. This decrease in IGF-1R-binding sites was shown to be caused by a 7-fold decrease in IGF-1R affinity. Furthermore, ScN2a showed no significant difference in IGF-1 induced proliferative response, despite the noticeable elevated IGF-1R expression, putatively explained by the reduced IGF-1R binding affinity. Additionally, IGF-1 stimulated IGF-1Rbeta tyrosine phosphorylation showed no major change in the dose-response between the cell types, possibly due to altered tyrosine kinase signaling in scrapie-infected neuroblastoma cells. Altogether these data indicate that scrapie infection affects the expression, binding affinity, and signal transduction mediated by the IGF-1R in neuroblastoma cells. Altered IGF-1R expression and function may weaken the trophic support in scrapie-infected neurons and thereby contribute to neurodegeneration in prion diseases.
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Affiliation(s)
- P Ostlund
- Department of Neurochemistry and Neurotoxicology, University of Stockholm, Svante Arrhenius v. 21A, S-10691 Stockholm, Sweden
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Diez M, DeArmond SJ, Groth D, Prusiner SB, Hökfelt T. Decreased MK-801 binding in discrete hippocampal regions of prion-infected mice. Neurobiol Dis 2001; 8:692-9. [PMID: 11493033 DOI: 10.1006/nbdi.2001.0404] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The neurochemical alterations associated with neurodegeneration in prion diseases are not well defined. It is therefore of interest to study the influence of prion infection on messenger molecules and their receptors. In the present study we have analyzed the possible involvement of NMDA receptors in prion-infected mice using ligand binding autoradiography and iodinated MK-801, a noncompetitive NMDA antagonist. The results show a reduced binding of MK-801 in discrete regions of hippocampus at 110 days after infection, that is before the appearance of behavioral symptoms. In addition, early transient increases in MK-801 binding were observed in several layers. The exact neuroanatomical correlate of these changes in MK-801 binding, as well as its functional significance in relation to prion symptomatology, remain to be analyzed.
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Affiliation(s)
- M Diez
- Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.
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35
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Abstract
Prion diseases are neurodegenerative disorders associated with a conformational change in the normal cellular isoform of the prion protein, PrP(C), to an abnormal scrapie isoform, PrP(SC). Unlike the alpha-helical PrP(C), the protease-resistant core of PrP(SC) is predominantly beta-sheet and possesses a tendency to polymerize into amyloid fibrils. We performed experiments with two synthetic human prion peptides, PrP(106-126) and PrP(127-147), to determine how peptide structure affects neurotoxicity and protein-membrane interactions. Peptide solutions possessing beta-sheet and amyloid structures were neurotoxic to PC12 cells in vitro and bound with measurable affinities to cholesterol-rich phospholipid membranes at ambient conditions, but peptide solutions lacking stable beta-sheet structures and amyloid content were nontoxic and possessed less than one tenth of the binding affinities of the amyloid-containing peptides. Regardless of structure, the peptide binding affinities to cholesterol-depleted membranes were greatly reduced. These results suggest that the beta-sheet and amyloid structures of the prion peptides give rise to their toxicity and membrane binding affinities and that membrane binding affinity, especially in cholesterol-rich environments, may be related to toxicity. Our results may have significance in understanding the role of the fibrillogenic cerebral deposits associated with some of the prion diseases in neurodegeneration and may have implications for other amyloidoses.
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Affiliation(s)
- D L Rymer
- Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA
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36
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Drieu K, Vranckx R, Benassayad C, Haourigi M, Hassid J, Yoa RG, Rapin JR, Nunez EA. Effect of the extract of Ginkgo biloba (EGb 761) on the circulating and cellular profiles of polyunsaturated fatty acids: correlation with the anti-oxidant properties of the extract. Prostaglandins Leukot Essent Fatty Acids 2000; 63:293-300. [PMID: 11090256 DOI: 10.1054/plef.2000.0217] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ginkgo biloba extract (EGb 761) has beneficial effects on cognitive functions in aging patients, and on various pathologies, including cardiovascular diseases. Although the extract is known to have antioxidant properties and improve membrane fluidity, the cellular mechanisms underlying these effects have not been determined. Here, we examined the in vivo effects of EGb 761 on circulating and cellular lipids. EGb 761 treatment induced significant increases in the levels of circulating polyunsaturated fatty acids (PUFAs), and a decrease in the saturation index SI (saturated/polyunsaturated species). Plasma triglycerides and cholesterol were not affected, while phospholipids were slightly increased at the higher dose of EGb 761. EGb 761 treatment also induced a significant increase in the levels of PUFAs in erythrocyte membranes, especially for the eicosapentaenoic acid (EPA omega 3), and a decrease in the saturation index. Moreover, the response of erythrocytes to oxidative stress was improved in EGb 761-treated animals (H(2)O(2)-induced cell lysis decreased by 50%). Considering that PUFAs are known to improve membrane fluidity and response to oxidative damage, and are precursors of signaling molecules such as prostaglandins, the effects of EGb 761 on circulating and cellular PUFAs may explain some of the pharmacological properties of Ginkgo biloba.
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Affiliation(s)
- K Drieu
- Institut Henri Beaufour-Ipsen, 24 rue Erlanger, 75781, Paris Cedex 16, France.
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37
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Herms JW, Korte S, Gall S, Schneider I, Dunker S, Kretzschmar HA. Altered intracellular calcium homeostasis in cerebellar granule cells of prion protein-deficient mice. J Neurochem 2000; 75:1487-92. [PMID: 10987828 DOI: 10.1046/j.1471-4159.2000.0751487.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies have indicated that recombinant cellular prion protein (PrP(C)), as well as a synthetic peptide of PrP(C), affects intracellular calcium homeostasis. To analyze whether calcium homeostasis in neurons is also affected by a loss of PrP(C), we performed microfluorometric calcium measurements on cultured cerebellar granule cells derived from prion protein-deficient (Prnp(0/0)) mice. The resting concentration of intracellular free calcium [Ca(2+)](i) was found to be slightly, but significantly, reduced in Prnp(0/0) mouse granule cell neurites. Moreover, we observed a highly significant reduction in the [Ca(2+)](i) increase after high potassium depolarization. Pharmacological studies further revealed that the L-type specific blocker nifedipine, which reduces the depolarization-induced [Ca(2+)](i) increase by 66% in wild-type granule cell somas, has no effect on [Ca(2+)](i) in Prnp(0/0) mouse granule cells. Patch-clamp measurements, however, did not reveal a reduced calcium influx through voltage-gated calcium channels in Prnp(0/0) mice. These data clearly indicate that loss of PrP(C) alters the intracellular calcium homeostasis of cultured cerebellar granule cells. There is no evidence, though, that this change is due to a direct alteration of voltage-gated calcium channels.
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Affiliation(s)
- J W Herms
- Department of Neuropathology, Georg-August Universität Göttingen, Göttingen, Germany
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Chiesa R, Harris DA. Nerve growth factor-induced differentiation does not alter the biochemical properties of a mutant prion protein expressed in PC12 cells. J Neurochem 2000; 75:72-80. [PMID: 10854249 DOI: 10.1046/j.1471-4159.2000.0750072.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Insertional and point mutations in the gene encoding the prion protein (PrP) are responsible for familial prion diseases. We have previously generated lines of Chinese hamster ovary cells that express PrP molecules carrying pathogenic mutations, and found that the mutant proteins display several biochemical properties reminiscent of PrP(Sc), the infectious isoform of PrP. To analyze the properties and effects of mutant PrP molecules expressed in cells with a neuronal phenotype, we have constructed stably transfected lines of PC12 cells that synthesize a PrP molecule carrying a nine-octapeptide insertion. We report here that this mutant PrP acquires scrapie-like properties, including detergent insolubility, protease resistance, and resistance to phospholipase cleavage of its glycolipid anchor. A detergent-insoluble and phospholipase-resistant form of the mutant protein is also released spontaneously into conditioned medium. These scrapie-like biochemical properties are quantitatively similar to those seen in Chinese hamster ovary cells and are not affected by differentiation of the PC12 cells into sympathetic neurons by nerve growth factor. Moreover, there is no detectable effect of mutant PrP expression on the morphology or viability of the cells in either the differentiated or undifferentiated state. These results indicate that conversion of mutant PrP into a PrP(Sc)-like form does not depend critically on the cellular context, and they suggest that mutant PrP expressed in cultured cells, even those having the phenotype of differentiated neurons, is not neurotoxic.
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Affiliation(s)
- R Chiesa
- Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri, USA
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Chapron Y, Peyrin JM, Crouzy S, Jaegly A, Dormont D. Theoretical analysis of the implication of PrP in neuronal death during transmissible subacute spongiform encephalopathies: hypothesis of a PrP oligomeric channel. J Theor Biol 2000; 204:103-11. [PMID: 10772851 DOI: 10.1006/jtbi.2000.1091] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transmissible subacute spongiform encephalopathies (TSE) are animal and human neurodegenerative diseases. The nature of the transmissible agent remains unknown. The specific molecular marker of these diseases is the abnormal isoform of the prion protein (PrP). This protein is encoded by a cellular gene and accumulates in a pathological isoform (PrPres) which is partially resistant to proteolysis. The tridimensional structure of this protein remains theoretical. F. Cohen proposed one of the most realistic models. According to this model and from molecular mechanics calculation, we suggest a PrP oligomeric ionic channel model that may be involved in TSE-induced neuronal apoptosis.
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Affiliation(s)
- Y Chapron
- CEA/DBMS/Biophysique Moléculaire et Cellulaire, URA/CNRS520, CEA/Grenoble, 17 Rue des Martyrs, Grenoble, 38054, France.
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40
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Abstract
Cultured cell lines infected with prions produce an abnormal isoform of the prion protein (PrP(Sc)). In order to derive cell lines producing sufficient quantities of PrP(Sc) for most studies, it has been necessary to subclone infected cultures and select the subclones producing the largest amounts of PrP(Sc). Since postinfection cloning can introduce differences between infected and uninfected cell lines, we sought an approach to generate prion-infected cell lines that would avoid clonal artifacts. Using an improved cell blot technique, which permits sensitive and rapid comparison of PrP(Sc) levels in multiple independent cell cultures, we discovered marked heterogeneity with regard to prion susceptibility in tumor cell sublines. We exploited this heterogeneity to derive sublines which are highly susceptible to prion infection and used these cells to generate prion-infected lines without further subcloning. These infected sublines can be compared to the cognate uninfected cultures without interference from cloning artifacts. We also used susceptible cell lines and our modified cell blot procedure to develop a sensitive and reproducible quantitative cell culture bioassay for prions. We found that the sublines were at least 100-fold more susceptible to strain RML prions than to strain ME7 prions. Comparisons between scrapie-susceptible and -resistant cell lines may reveal factors that modulate prion propagation.
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Affiliation(s)
- P J Bosque
- Institute for Neurodegenerative Diseases, University of California, San Francisco, California 94143-0518, USA
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Hegde RS, Tremblay P, Groth D, DeArmond SJ, Prusiner SB, Lingappa VR. Transmissible and genetic prion diseases share a common pathway of neurodegeneration. Nature 1999; 402:822-6. [PMID: 10617204 DOI: 10.1038/45574] [Citation(s) in RCA: 214] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Prion diseases can be infectious, sporadic and genetic. The infectious forms of these diseases, including bovine spongiform encephalopathy and Creutzfeldt-Jakob disease, are usually characterized by the accumulation in the brain of the transmissible pathogen, an abnormally folded isoform of the prion protein (PrP) termed PrPSc. However, certain inherited PrP mutations appear to cause neurodegeneration in the absence of PrPSc, working instead by favoured synthesis of CtmPrP, a transmembrane form of PrP. The relationship between the neurodegeneration seen in transmissible prion diseases involving PrPSc and that associated with ctmPrP has remained unclear. Here we find that the effectiveness of accumulated PrPSc in causing neurodegenerative disease depends upon the predilection of host-encoded PrP to be made in the ctmPrP form. Furthermore, the time course of PrPSc accumulation in transmissible prion disease is followed closely by increased generation of CtmPrP. Thus, the accumulation of PrPSc appears to modulate in trans the events involved in generating or metabolising CtmPrP. Together, these data suggest that the events of CtmPrP-mediated neurodegeneration may represent a common step in the pathogenesis of genetic and infectious prion diseases.
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Affiliation(s)
- R S Hegde
- Department of Physiology, University of California, San Francisco 94143, USA
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Abstract
Prion diseases are fatal neurodegenerative disorders of humans and animals that are important because of their impact on public health and because they exemplify a novel mechanism of infectivity and biological information transfer. These diseases are caused by conformational conversion of a normal host glycoprotein (PrPC) into an infectious isoform (PrPSc) that is devoid of nucleic acid. This review focuses on the current understanding of prion diseases at the cell biological level. The characteristics of the diseases are introduced, and a brief history and description of the prion hypothesis are given. Information is then presented about the structure, expression, biosynthesis, and possible function of PrPC, as well as its posttranslational processing, cellular localization, and trafficking. The latest findings concerning PrPSc are then discussed, including cell culture systems used to generate this pathogenic isoform, the subcellular distribution of the protein, its membrane attachment, proteolytic processing, and its kinetics and sites of synthesis. Information is also provided on molecular models of the PrPC-->PrPSc conversion reaction and the possible role of cellular chaperones. The review concludes with suggestions of several important avenues for future investigation.
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Affiliation(s)
- D A Harris
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Florio T, Thellung S, Amico C, Robello M, Salmona M, Bugiani O, Tagliavini F, Forloni G, Schettini G. Prion protein fragment 106-126 induces apoptotic cell death and impairment of L-type voltage-sensitive calcium channel activity in the GH3 cell line. J Neurosci Res 1998; 54:341-52. [PMID: 9819139 DOI: 10.1002/(sici)1097-4547(19981101)54:3<341::aid-jnr5>3.0.co;2-g] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The prion diseases are transmissible neurodegenerative pathologies characterized by the accumulation of altered forms of the prion protein (PrP), termed PrP(Sc), in the brain. Previous studies have shown that a synthetic peptide homologous to residues 106-126 of PrP (PrP 106-126) maintains many characteristics of PrP(Sc), i.e., the ability to form amyloid fibrils and to induce apoptosis in neurons. We have investigated the intracellular mechanisms involved in the cellular degeneration induced by PrP 106-126, using the GH3 cells as a model of excitable cells. When assayed in serum-deprived conditions (48 hr), PrP 106-126 (50 microM) induced cell death time-dependently, and this process showed the characteristics of the apoptosis. This effect was specific because a peptide with a scrambled sequence of PrP 106-126 was not effective. Then we performed microfluorimetric analysis of single cells to monitor intracellular calcium concentrations and showed that PrP 106-126 caused a complete blockade of the increase in the cytosolic calcium levels induced by K+ (40 mM) depolarization. Conversely, the scrambled peptide was ineffective. The L-type voltage-sensitive calcium channel blocker nicardipine (1 microM) also induced apoptosis in GH3 cells, suggesting that the blockade of Ca2+ entry through this class of calcium channels may cause GH3 apoptotic cell death. We thus analyzed, by means of electrophysiological studies, whether Prp 106-126 modulate L-type calcium channels activity and demonstrated that the apoptotic effect of PrP 106-126 was due to a dose-dependent inactivation of the L-type calcium channels. These data demonstrate that the prion protein fragment 106-126 induces a GH3 apoptotic cell death inducing a selective inhibition of the activity of the L-type voltage-sensitive calcium channels.
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Affiliation(s)
- T Florio
- Istituto di Farmacologia, Facoltà di Medicina, Università di Genova, Centro di Biotecnologie Avanzate, Servizio di Farmacologia Istituto Nazionale per la Ricerca sul Cancro (IST), Italy
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Lerner RA. A hypothesis about the endogenous analogue of general anesthesia. Proc Natl Acad Sci U S A 1997; 94:13375-7. [PMID: 9391028 PMCID: PMC33784 DOI: 10.1073/pnas.94.25.13375] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/1997] [Indexed: 02/05/2023] Open
Affiliation(s)
- R A Lerner
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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45
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DeArmond SJ, Sánchez H, Yehiely F, Qiu Y, Ninchak-Casey A, Daggett V, Camerino AP, Cayetano J, Rogers M, Groth D, Torchia M, Tremblay P, Scott MR, Cohen FE, Prusiner SB. Selective neuronal targeting in prion disease. Neuron 1997; 19:1337-48. [PMID: 9427256 DOI: 10.1016/s0896-6273(00)80424-9] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The pattern of scrapie prion protein (PrP(Sc)) accumulation in the brain is different for each prion strain. We tested whether the PrP(Sc) deposition pattern is influenced by the Asn-linked oligosaccharides of PrP(C) in transgenic mice. Deletion of the first oligosaccharide altered PrP(C) trafficking and prevented infection with two prion strains. Deletion of the second did not alter PrP(C) trafficking, permitted infection with one prion strain, and had a profound effect on the PrP(Sc) deposition pattern. Our data raise the possibility that glycosylation can modify the conformation of PrP(C). Glycosylation could affect the affinity of PrP(C) for a particular conformer of PrP(Sc), thereby determining the rate of nascent PrP(Sc) formation and the specific patterns of PrP(Sc) deposition.
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Affiliation(s)
- S J DeArmond
- Department of Pathology, University of California, San Francisco 94143, USA
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Schätzl HM, Laszlo L, Holtzman DM, Tatzelt J, DeArmond SJ, Weiner RI, Mobley WC, Prusiner SB. A hypothalamic neuronal cell line persistently infected with scrapie prions exhibits apoptosis. J Virol 1997; 71:8821-31. [PMID: 9343242 PMCID: PMC192348 DOI: 10.1128/jvi.71.11.8821-8831.1997] [Citation(s) in RCA: 234] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Neuronal death and vacuolation are characteristics of the CNS degeneration found in prion diseases. Relatively few cultured cell lines have been identified that can be persistently infected with scrapie prions, and none of these cells show cytopathologic changes reminiscent of prion neuropathology. The differentiated neuronal cell line GT1, established from gonadotropin hormone releasing-hormone neurons immortalized by genetically targeted tumorigenesis in transgenic mice (P. L. Mellon, JJ. Windle, P. C. Goldsmith, C. A. Padula, J. L. Roberts, and R. I. Weiner, Neuron 5:1-10, 1990), was examined for its ability to support prion formation. We found that GT1 cells could be persistently infected with mouse RML prions and that conditioned medium from infected cells could transfer prions to uninfected cells. In many but not all experiments, a subpopulation of cells showed reduced viability, morphological signs of neurodegeneration and vacuolation, and features of apoptosis. Subclones of GT1 cells that were stably transfected with the trk4 gene encoding the high-affinity nerve growth factor (NGF) receptor (GT1-trk) could also be persistently infected. NGF increased the viability of the scrapie-infected GT1-trk cells and reduced the morphological and biochemical signs of vacuolation and apoptosis. GT1 cells represent a novel system for studying the molecular mechanisms underlying prion infectivity and subsequent neurodegenerative changes.
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Affiliation(s)
- H M Schätzl
- Department of Neurology, University of California, San Francisco 94143, USA
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