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Abstract
Introduction: Prion diseases are a class of rare and fatal neurodegenerative diseases for which no cure is currently available. They are characterized by conformational conversion of cellular prion protein (PrPC) into the disease-associated 'scrapie' isoform (PrPSc). Under an etiological point of view, prion diseases can be divided into acquired, genetic, and idiopathic form, the latter of which are the most frequent.Areas covered: Therapeutic approaches targeting prion diseases are based on the use of chemical and nature-based compounds, targeting either PrPC or PrPSc or other putative player in pathogenic mechanism. Other proposed anti-prion treatments include passive and active immunization strategies, peptides, aptamers, and PrPC-directed RNA interference techniques. The treatment efficacy has been mainly assessed in cell lines or animal models of the disease testing their ability to reduce prion accumulation.Expert opinion: The assessed strategies focussing on the identification of an efficient anti-prion therapy faced various issues, which go from permeation of the blood brain barrier to immunological tolerance of the host. Indeed, the use of combinatory approaches, which could boost a synergistic anti-prion effect and lower the potential side effects of single treatments and may represent an extreme powerful and feasible way to tackle prion disease.
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Affiliation(s)
- Marco Zattoni
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore Di Studi Avanzati (SISSA), Trieste, Italy
| | - Giuseppe Legname
- Laboratory of Prion Biology, Department of Neuroscience, Scuola Internazionale Superiore Di Studi Avanzati (SISSA), Trieste, Italy
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2
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Krance SH, Luke R, Shenouda M, Israwi AR, Colpitts SJ, Darwish L, Strauss M, Watts JC. Cellular models for discovering prion disease therapeutics: Progress and challenges. J Neurochem 2020; 153:150-172. [PMID: 31943194 DOI: 10.1111/jnc.14956] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/22/2022]
Abstract
Prions, which cause fatal neurodegenerative disorders such as Creutzfeldt-Jakob disease, are misfolded and infectious protein aggregates. Currently, there are no treatments available to halt or even delay the progression of prion disease in the brain. The infectious nature of prions has resulted in animal paradigms that accurately recapitulate all aspects of prion disease, and these have proven to be instrumental for testing the efficacy of candidate therapeutics. Nonetheless, infection of cultured cells with prions provides a much more powerful system for identifying molecules capable of interfering with prion propagation. Certain lines of cultured cells can be chronically infected with various types of mouse prions, and these models have been used to unearth candidate anti-prion drugs that are at least partially efficacious when administered to prion-infected rodents. However, these studies have also revealed that not all types of prions are equal, and that drugs active against mouse prions are not necessarily effective against prions from other species. Despite some recent progress, the number of cellular models available for studying non-mouse prions remains limited. In particular, human prions have proven to be particularly challenging to propagate in cultured cells, which has severely hindered the discovery of drugs for Creutzfeldt-Jakob disease. In this review, we summarize the cellular models that are presently available for discovering and testing drugs capable of blocking the propagation of prions and highlight challenges that remain on the path towards developing therapies for prion disease.
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Affiliation(s)
- Saffire H Krance
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Russell Luke
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Marc Shenouda
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.,Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
| | - Ahmad R Israwi
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Sarah J Colpitts
- Department of Immunology, University of Toronto, Toronto, ON, Canada
| | - Lina Darwish
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Maximilian Strauss
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.,Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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Dar KB, Bhat AH, Amin S, Reshi BA, Zargar MA, Masood A, Ganie SA. Elucidating Critical Proteinopathic Mechanisms and Potential Drug Targets in Neurodegeneration. Cell Mol Neurobiol 2019; 40:313-345. [PMID: 31584139 DOI: 10.1007/s10571-019-00741-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/06/2019] [Indexed: 12/18/2022]
Abstract
Neurodegeneration entails progressive loss of neuronal structure as well as function leading to cognitive failure, apathy, anxiety, irregular body movements, mood swing and ageing. Proteomic dysregulation is considered the key factor for neurodegeneration. Mechanisms involving deregulated processing of proteins such as amyloid beta (Aβ) oligomerization; tau hyperphosphorylation, prion misfolding; α-synuclein accumulation/lewy body formation, chaperone deregulation, acetylcholine depletion, adenosine 2A (A2A) receptor hyperactivation, secretase deregulation, leucine-rich repeat kinase 2 (LRRK2) mutation and mitochondrial proteinopathies have deeper implications in neurodegenerative disorders. Better understanding of such pathological mechanisms is pivotal for exploring crucial drug targets. Herein, we provide a comprehensive outlook about the diverse proteomic irregularities in Alzheimer's, Parkinson's and Creutzfeldt Jakob disease (CJD). We explicate the role of key neuroproteomic drug targets notably Aβ, tau, alpha synuclein, prions, secretases, acetylcholinesterase (AchE), LRRK2, molecular chaperones, A2A receptors, muscarinic acetylcholine receptors (mAchR), N-methyl-D-aspartate receptor (NMDAR), glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) and mitochondrial/oxidative stress-related proteins for combating neurodegeneration and associated cognitive and motor impairment. Cross talk between amyloidopathy, synucleinopathy, tauopathy and several other proteinopathies pinpoints the need to develop safe therapeutics with ability to strike multiple targets in the aetiology of the neurodegenerative disorders. Therapeutics like microtubule stabilisers, chaperones, kinase inhibitors, anti-aggregation agents and antibodies could serve promising regimens for treating neurodegeneration. However, drugs should be target specific, safe and able to penetrate blood-brain barrier.
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Affiliation(s)
- Khalid Bashir Dar
- Department of Clinical Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India.,Department of Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India
| | - Aashiq Hussain Bhat
- Department of Clinical Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India.,Department of Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India
| | - Shajrul Amin
- Department of Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India
| | - Bilal Ahmad Reshi
- Department of Biotechnology, Faculty of Biological Sciences, University of Kashmir, Srinagar, India
| | - Mohammad Afzal Zargar
- Department of Clinical Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India
| | - Akbar Masood
- Department of Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India
| | - Showkat Ahmad Ganie
- Department of Clinical Biochemistry, Faculty of Biological Sciences, University of Kashmir, Srinagar, India.
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Kang SG, Kim C, Aiken J, Yoo HS, McKenzie D. Dual MicroRNA to Cellular Prion Protein Inhibits Propagation of Pathogenic Prion Protein in Cultured Cells. Mol Neurobiol 2017; 55:2384-2396. [PMID: 28357807 DOI: 10.1007/s12035-017-0495-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/14/2017] [Indexed: 01/08/2023]
Abstract
Prion diseases are fatal transmissible neurodegenerative disorders affecting humans and various mammals. In spite of intensive efforts, there is no effective cure or treatment for prion diseases. Cellular forms of prion protein (PrPC) is essential for propagation of abnormal isoforms of prion protein (PrPSc) and pathogenesis. The effect of an artificial dual microRNA (DmiR) on PrPC suppression and resultant inhibition of prion replication was determined using prion-infectible cell cultures: differentiated C2C12 culture and primary mixed neuronal and glial cells culture (MNGC). Processing of DmiR by prion-susceptible myotubes, but not by reserve cells, in differentiated C2C12 culture slowed prion replication, implying an importance of cell type-specific PrPC targeting. In MNGC, reduction of PrPC with DmiR was effective for suppressing prion replication. MNGC lentivirally transduced with non-targeting control miRNAs (scrambled) reduced prion replication at a level similar to that with a synthetic analogue of viral RNA, poly I:C. The results suggest that a synergistic combination of the immunostimulatory RNA duplexes (miRNA) and PrPC silencing with DmiR might augment a therapeutic potential of RNA interference.
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Affiliation(s)
- Sang-Gyun Kang
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada.,Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB, Canada
| | - Chiye Kim
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Judd Aiken
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada.,Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB, Canada
| | - Han Sang Yoo
- Department of Infectious Diseases, College of Veterinary Medicine, BK21 PLUS, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Debbie McKenzie
- Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB, Canada. .,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
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Goold R, McKinnon C, Tabrizi SJ. Prion degradation pathways: Potential for therapeutic intervention. Mol Cell Neurosci 2015; 66:12-20. [PMID: 25584786 PMCID: PMC4503822 DOI: 10.1016/j.mcn.2014.12.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 12/16/2014] [Indexed: 12/18/2022] Open
Abstract
Prion diseases are fatal neurodegenerative disorders. Pathology is closely linked to the misfolding of native cellular PrP(C) into the disease-associated form PrP(Sc) that accumulates in the brain as disease progresses. Although treatments have yet to be developed, strategies aimed at stimulating the degradation of PrP(Sc) have shown efficacy in experimental models of prion disease. Here, we describe the cellular pathways that mediate PrP(Sc) degradation and review possible targets for therapeutic intervention. This article is part of a Special Issue entitled 'Neuronal Protein'.
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Affiliation(s)
- Rob Goold
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, United Kingdom
| | - Chris McKinnon
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, United Kingdom
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, United Kingdom.
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Onodera T, Sakudo A, Tsubone H, Itohara S. Review of studies that have used knockout mice to assess normal function of prion protein under immunological or pathophysiological stress. Microbiol Immunol 2015; 58:361-74. [PMID: 24866463 DOI: 10.1111/1348-0421.12162] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 05/22/2014] [Accepted: 05/26/2014] [Indexed: 12/29/2022]
Abstract
Deletion of cellular isoform of prion protein (PrP(C)) increases neuronal predisposition to damage by modulating apoptosis and the negative consequences of oxidative stress. In vivo studies have demonstrated that PrP(C)-deficient mice are more prone to seizure, depression, and induction of epilepsy and experience extensive cerebral damage following ischemic challenge or viral infection. In addition, adenovirus-mediated overexpression of PrP(C) reduces brain damage in rat models of cerebral ischemia. In experimental autoimmune encephalomyelitis, PrP(C)-deficient mice reportedly have a more aggressive disease onset and less clinical improvement during the chronic phase than wild-type mice mice. In mice given oral dextran sulfate, PrP(C) has a potential protective role against inflammatory bowel disease. PrP(C)-deficient mice demonstrate significantly greater increases in blood glucose concentrations after intraperitoneal injection of glucose than wild-type mice. Further in vivo challenges to PrP gene-deficient models and conditional knockout models with siRNA and in vivo administration of PrP-ligating agents may assist in refining knowledge of the lymphoid function of PrP(C) and predicting the effects of anti-PrP treatment on the immune system. Together, these findings indicate that PrP(C) may have multiple neuroprotective and anti-inflammatory roles, which explains why this protein is so widely expressed.
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Affiliation(s)
- Takashi Onodera
- Research Center for Food Safety, School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657
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Boese AS, Majer A, Saba R, Booth SA. Small RNA drugs for prion disease: a new frontier. Expert Opin Drug Discov 2013; 8:1265-84. [DOI: 10.1517/17460441.2013.818976] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Nazor Friberg K, Hung G, Wancewicz E, Giles K, Black C, Freier S, Bennett F, Dearmond SJ, Freyman Y, Lessard P, Ghaemmaghami S, Prusiner SB. Intracerebral Infusion of Antisense Oligonucleotides Into Prion-infected Mice. MOLECULAR THERAPY. NUCLEIC ACIDS 2012; 1:e9. [PMID: 23344724 PMCID: PMC3381600 DOI: 10.1038/mtna.2011.6] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mice deficient for the cellular prion protein (PrPC) do not develop prion disease; accordingly, gene-based strategies to diminish PrPC expression are of interest. We synthesized a series of chemically modified antisense oligonucleotides (ASOs) targeted against mouse Prnp messenger RNA (mRNA) and identified those that were most effective in decreasing PrPC expression. Those ASOs were also evaluated in scrapie-infected cultured cells (ScN2a) for their efficacy in diminishing the levels of the disease-causing prion protein (PrPSc). When the optimal ASO was infused intracerebrally into FVB mice over a 14-day period beginning 1 day after infection with the Rocky Mountain Laboratory (RML) strain of mouse prions, a prolongation of the incubation period of almost 2 months was observed. Whether ASOs can be used to develop an effective therapy for patients dying of Creutzfeldt–Jakob disease remains to be established.
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Affiliation(s)
- Karah Nazor Friberg
- Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, California, USA
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Panigaj M, Glier H, Wildova M, Holada K. Expression of prion protein in mouse erythroid progenitors and differentiating murine erythroleukemia cells. PLoS One 2011; 6:e24599. [PMID: 21912705 PMCID: PMC3166331 DOI: 10.1371/journal.pone.0024599] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 08/15/2011] [Indexed: 12/21/2022] Open
Abstract
Prion diseases have been observed to deregulate the transcription of erythroid genes, and prion protein knockout mice have demonstrated a diminished response to experimental anemia. To investigate the role of the cellular prion protein (PrP(C)) in erythropoiesis, we studied the protein's expression on mouse erythroid precursors in vivo and utilized an in vitro model of the erythroid differentiation of murine erythroleukemia cells (MEL) to evaluate the effect of silencing PrP(C) through RNA interference.The expression of PrP(C) and selected differentiation markers was analyzed by quantitative multicolor flow cytometry, western blot analysis and quantitative RT-PCR. The silencing of PrP(C) expression in MEL cells was achieved by expression of shRNAmir from an integrated retroviral vector genome. The initial upregulation of PrP(C) expression in differentiating erythroid precursors was detected both in vivo and in vitro, suggesting PrP(C)'s importance to the early stages of differentiation. The upregulation was highest on early erythroblasts (16200±3700 PrP(C) / cell) and was followed by the gradual decrease of PrP(C) level with the precursor's maturation reaching 470±230 PrP(C) / cell on most mature CD71(-)Ter119(+) small precursors. Interestingly, the downregulation of PrP(C) protein with maturation of MEL cells was not accompanied by the decrease of PrP mRNA. The stable expression of anti-Prnp shRNAmir in MEL cells led to the efficient (>80%) silencing of PrP(C) levels. Cell growth, viability, hemoglobin production and the transcription of selected differentiation markers were not affected by the downregulation of PrP(C).In conclusion, the regulation of PrP(C) expression in differentiating MEL cells mimics the pattern detected on mouse erythroid precursors in vivo. Decrease of PrP(C) protein expression during MEL cell maturation is not regulated on transcriptional level. The efficient silencing of PrP(C) levels, despite not affecting MEL cell differentiation, enables created MEL lines to be used for studies of PrP(C) cellular function.
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Affiliation(s)
- Martin Panigaj
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - Hana Glier
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - Marcela Wildova
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - Karel Holada
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
- * E-mail:
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Silva JL, Vieira TCRG, Gomes MPB, Rangel LP, Scapin SMN, Cordeiro Y. Experimental approaches to the interaction of the prion protein with nucleic acids and glycosaminoglycans: Modulators of the pathogenic conversion. Methods 2010; 53:306-17. [PMID: 21145399 DOI: 10.1016/j.ymeth.2010.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 12/02/2010] [Indexed: 11/17/2022] Open
Abstract
The concept that transmissible spongiform encephalopathies (TSEs) are caused only by proteins has changed the traditional paradigm that disease transmission is due solely to an agent that carries genetic information. The central hypothesis for prion diseases proposes that the conversion of a cellular prion protein (PrP(C)) into a misfolded, β-sheet-rich isoform (PrP(Sc)) accounts for the development of (TSE). There is substantial evidence that the infectious material consists chiefly of a protein, PrP(Sc), with no genomic coding material, unlike a virus particle, which has both. However, prions seem to have other partners that chaperone their activities in converting the PrP(C) into the disease-causing isoform. Nucleic acids (NAs) and glycosaminoglycans (GAGs) are the most probable accomplices of prion conversion. Here, we review the recent experimental approaches that have been employed to characterize the interaction of prion proteins with nucleic acids and glycosaminoglycans. A PrP recognizes many nucleic acids and GAGs with high affinities, and this seems to be related to a pathophysiological role for this interaction. A PrP binds nucleic acids and GAGs with structural selectivity, and some PrP:NA complexes can become proteinase K-resistant, undergoing amyloid oligomerization and conversion to a β-sheet-rich structure. These results are consistent with the hypothesis that endogenous polyanions (such as NAs and GAGs) may accelerate the rate of prion disease progression by acting as scaffolds or lattices that mediate the interaction between PrP(C) and PrP(Sc) molecules. In addition to a still-possible hypothesis that nucleic acids and GAGs, especially those from the host, may modulate the conversion, the recent structural characterization of the complexes has raised the possibility of developing new diagnostic and therapeutic strategies.
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Affiliation(s)
- Jerson L Silva
- Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Brazil.
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Omar A, Jovanovic K, Da Costa Dias B, Gonsalves D, Moodley K, Caveney R, Mbazima V, Weiss SFT. Patented biological approaches for the therapeutic modulation of the 37 kDa/67 kDa laminin receptor. Expert Opin Ther Pat 2010; 21:35-53. [DOI: 10.1517/13543776.2011.539203] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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12
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Prion protein self-interactions: A gateway to novel therapeutic strategies? Vaccine 2010; 28:7810-23. [DOI: 10.1016/j.vaccine.2010.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 08/31/2010] [Accepted: 09/03/2010] [Indexed: 11/19/2022]
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Pulford B, Reim N, Bell A, Veatch J, Forster G, Bender H, Meyerett C, Hafeman S, Michel B, Johnson T, Wyckoff AC, Miele G, Julius C, Kranich J, Schenkel A, Dow S, Zabel MD. Liposome-siRNA-peptide complexes cross the blood-brain barrier and significantly decrease PrP on neuronal cells and PrP in infected cell cultures. PLoS One 2010; 5:e11085. [PMID: 20559428 PMCID: PMC2885418 DOI: 10.1371/journal.pone.0011085] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 05/20/2010] [Indexed: 01/23/2023] Open
Abstract
Background Recent advances toward an effective therapy for prion diseases employ RNA interference to suppress PrPC expression and subsequent prion neuropathology, exploiting the phenomenon that disease severity and progression correlate with host PrPC expression levels. However, delivery of lentivirus encoding PrP shRNA has demonstrated only modest efficacy in vivo. Methodology/Principal Findings Here we describe a new siRNA delivery system incorporating a small peptide that binds siRNA and acetylcholine receptors (AchRs), acting as a molecular messenger for delivery to neurons, and cationic liposomes that protect siRNA-peptide complexes from serum degradation. Conclusions/Significance Liposome-siRNA-peptide complexes (LSPCs) delivered PrP siRNA specifically to AchR-expressing cells, suppressed PrPC expression and eliminated PrPRES formation in vitro. LSPCs injected intravenously into mice resisted serum degradation and delivered PrP siRNA throughout the brain to AchR and PrPC-expressing neurons. These data promote LSPCs as effective vehicles for delivery of PrP and other siRNAs specifically to neurons to treat prion and other neuropathological diseases.
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Affiliation(s)
- Bruce Pulford
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Natalia Reim
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Aimee Bell
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jessica Veatch
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Genevieve Forster
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Heather Bender
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Crystal Meyerett
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Scott Hafeman
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Brady Michel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Theodore Johnson
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - A. Christy Wyckoff
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Gino Miele
- Pfizer Global Research & Development, Translational Medicine Research Collaboration, Dundee, Scotland
| | - Christian Julius
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jan Kranich
- Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Alan Schenkel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Steven Dow
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Mark D. Zabel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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Provost P. MicroRNAs as a molecular basis for mental retardation, Alzheimer's and prion diseases. Brain Res 2010; 1338:58-66. [PMID: 20347722 DOI: 10.1016/j.brainres.2010.03.069] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 03/15/2010] [Accepted: 03/18/2010] [Indexed: 11/28/2022]
Abstract
MicroRNAs (miRNAs) are small, approximately 21- to 23-nucleotide (nt) non-coding RNA species that act as key regulators of gene expression along a central and well-defined cellular process known as RNA silencing, and involving the recognition and translational control of specific messenger RNA (mRNAs). Generated through the well-orchestrated and sequential processing of miRNA precursor molecules, mature miRNAs are subsequently incorporated into miRNA-containing ribonucleoprotein effector complexes to regulate mRNA translation through the recognition of specific binding sites of imperfect complementarity located mainly in the 3' untranslated region. Predicted to regulate up to 90% of the genes in humans, miRNAs may thus control cellular processes in all cells and tissues of the human body. Likely to play a central role in health and disease, a dysfunctional miRNA-based regulation of gene expression may represent the main etiologic factor underlying diseases affecting major organs, such as the brain. In this review article, the molecular mechanisms underlying the role and function of miRNAs in the regulation of genes involved in neurological and neurodegenerative diseases will be discussed, with a focus on the fragile X syndrome, Alzheimer's disease (AD) and prion disease.
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Affiliation(s)
- Patrick Provost
- CHUL Research Center/CHUQ and Faculty of Medicine, Université Laval, Quebec, QC, Canada.
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Kang SG, Roh YM, Kang ML, Kim YS, Yoo HS. Mouse neuronal cells expressing exogenous bovine PRNP and simultaneous downregulation of endogenous mouse PRNP using siRNAs. Prion 2010; 4:32-7. [PMID: 20215868 DOI: 10.4161/pri.4.1.11218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Prion diseases, which are called transmissible spongiform encephalopathies (TSEs), comprise a group of fatal infectious neurodegenerative disorders. Investigation of prion strains and generation of species dependent TSE model are necessary to understand pathogenesis of the disease. To establish a BSE-specific in vitro cell culture model, N2a and GT1 mouse neuronal cell lines were generated to express the bovine prion protein by transfection of the bovine prion gene (Prnp). In addition, the endogenous mouse prion protein was suppressed in N2a, NbP, GT1 and GbP cell lines using the siRNA duplexes, siRNA1 and siRNA2 that target the N- and C-termini of murine Prnp, respectively. Both siRNA1 and siRNA2 effectively decreased murine prion protein levels by more than 80% and the downregulation efficacy was increased in siRNA dose-dependent manner. The greatest downregulation was observed 48 h after siRNA delivery. The moPrnp knockdown NbP and GbP cell lines and the Prnp-targeting siRNA technique established in the present study would be useful tools for dissecting the basic mechanisms of prion infection, especially for BSE.
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Affiliation(s)
- Sang-Gyun Kang
- Department of Infectious Diseases, College of Veterinary Medicine, KRF Zoonotic Disease Priority Research Institute and BK21 Program for Veterinary Science, Seoul National University, Seoul, Republic of Korea
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16
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Downregulation of lentivirus-mediated ILK RNAi on tractional force generation in human retinal Müller cells. Acta Pharmacol Sin 2009; 30:1625-33. [PMID: 19915584 DOI: 10.1038/aps.2009.154] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
AIM To investigate the effect of lentivirus-mediated integrin-linked kinase (ILK) RNA interference (RNAi) on human retinal Müller cells transdifferentiation into contractile myofibroblasts. METHODS A lentiviral vector expressing ILK-specific shRNA was constructed and introduced into cultured retinal Müller cells. Silencing of the ILK gene was identified by real time RT-PCR and Western blot. The Müller cell phenotype change was confirmed by immunodetection of alpha-smooth muscle actin (alpha-SMA) stress fiber formation. The generation of tractional force was assessed using a tissue culture assay with cells incubated in three-dimensional collagen gels; cell migration was determined by the Boyden chamber method, using 10% FBS as a chemotactic factor. RESULTS Significant decreases in ILK mRNA and protein expression were detected in Müller cells carrying lentiviral ILK-shRNA vector. Cells treated with anti-ILK siRNA showed less alpha-SMA stress fiber formation under hypoxic conditions or cell subcultivation. Lentiviral ILK-shRNA vector transfection also significantly reduced cell migration and cell-mediated gel contraction. CONCLUSION Lentivirus-mediated ILK RNAi decreased cell migration and contractile force generation by inhibiting alpha-SMA stress fiber formation in human retinal Müller cells. This tool might be useful to treat ocular fibroproliferative diseases associated with transdifferentiated Müller cells.
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Wang S, Lv X, Zhang K, Lin T, Liu X, Yuan J, Dai Y, Li N. Knockdown of the prion gene expression by RNA interference in bovine fibroblast cells. Mol Biol Rep 2009; 37:3193-8. [PMID: 19821149 DOI: 10.1007/s11033-009-9900-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Accepted: 10/02/2009] [Indexed: 01/14/2023]
Abstract
PRNP is the gene encoding prion protein whose misfolded and β-sheet-rich isoform is the infectious agent of transmissible spongiform encephalopathy (TSE). TSE, also called prion diseases, cause fatal neurodegenerative and transmissible disorders in human and animals. Among these diseases, bovine spongiform encephalopathy (BSE) has tremendous impact on economy and human health in the world. In the present study, we hypothesize suppression of the PRNP gene expression could raise resistance to BSE in cattle by using vector-based small interfering RNA (siRNA) expression systems. Therefore, the objective was to screen effective DNA-encoding short hairpin RNAs (shRNAs) which could knockdown the PRNP gene expression in bovine fibroblast cells. Human U6 promoter was employed to drive shRNA transcription from the DNA vector, and seven shRNAs, that designed to target coding region and 3' untranslated region of the PRNP gene, were selected. Four out of seven shRNAs tested were found to be effective in inhibiting the PRNP gene expression, and the most significant suppression level was as much as 62.9% evidenced by real-time RT-PCR. Furthermore, the protein abundance was obviously reduced compared to the control. Overall, the present study demonstrated that vector-based siRNA expression systems is an efficient approach to knockdown the PRNP gene expression in bovine fibroblast cells and thereby provide donor cells for somatic cell nuclear cloning to produce cattle that is resistant to prion related diseases.
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Affiliation(s)
- Shaohua Wang
- State Key Laboratory for Agrobiotechnology, College of Biological Science, China Agricultural University, Yuanmingyuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China.
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Kim Y, Han B, Titlow W, Mays CE, Kwon M, Ryou C. Utility of RNAi-mediated prnp gene silencing in neuroblastoma cells permanently infected by prions: potentials and limitations. Antiviral Res 2009; 84:185-93. [PMID: 19748523 DOI: 10.1016/j.antiviral.2009.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 07/04/2009] [Accepted: 09/04/2009] [Indexed: 11/19/2022]
Abstract
Prion diseases are incurable, transmissible neurodegenerative disorders in humans and animals. Because the disease-associated isoform of prion protein, PrP(Sc), is conformationally converted from cellular prion protein, PrP(C), knockdown of PrP(C) expression by RNA interference (RNAi) implicates therapy for prion diseases. In this study, introduction of small interfering (si) and small hairpin (sh) RNAs targeting the prion protein gene (prnp) transcripts triggered specific gene silencing and reduced the PrP(C) level in both prion-free and -infected neuroblastoma cell lines. Furthermore, this approach suppressed PrP(Sc) formation and ultimately eliminated PrP(Sc) from prion-infected cell lines. However, prolonged culture of cured cells resulted in reappearance of PrP(Sc) in the cell population, presumably by de novo PrP(Sc) formation from residual PrP(C) uncontrolled by RNAi and PrP(Sc) remained under the detection limit. Protein misfolding cyclic amplification assays further confirmed that lysate of cured cells was sufficient to support PrP(Sc) propagation. Our data not only suggest a potential treatment option but also implicate a caveat for using an RNAi approach for prion diseases. These findings provide critical information required to advance RNAi-based prevention and therapy for prion diseases of humans and animals.
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Affiliation(s)
- Younghwan Kim
- Sanders-Brown Center on Aging, Department of Microbiology, Immunology and Molecular Genetics, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
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White MD, Mallucci GR. Therapy for prion diseases: Insights from the use of RNA interference. Prion 2009; 3:121-8. [PMID: 19597349 DOI: 10.4161/pri.3.3.9289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Insights into the molecular basis and the temporal evolution of neurotoxicity in prion disease are increasing, and recent work in mice leads to new avenues for targeting treatment of these disorders. Using lentivirally mediated RNA interference (RNAi) against native prion protein (PrP), White et al. report the first therapeutic intervention that results in neuronal rescue, prevents symptoms and increases survival in mice with established prion disease.(1) Both the target and the timing of treatment here are crucial to the effectiveness of this strategy: the formation of the neurotoxic prion agent is prevented at a point when diseased neurons can still be saved from death. But the data also give new insights into the timing of treatment in the context of the pattern of spread of prion infection throughout the brain, with implications for developing the most effective treatments.
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Affiliation(s)
- Melanie D White
- Centre for Neuroscience Research, University of Edinburgh, UK
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Abstract
The transmissible spongiform encephalopathies are rapidly progressive and invariably fatal neurodegenerative diseases for which there are no proven efficacious treatments. Many approaches have been undertaken to find ways to prevent, halt, or reverse these prion diseases, with limited success to date. However, as both our understanding of pathogenesis and our ability to detect early disease increases, so do our potential therapeutic targets and our chances of finding effective drugs. There is increasing pressure to find effective decontaminants for blood supplies, as variant Creutzfeldt Jakob Disease (vCJD) has been shown to be transmissible by blood, and to find non-toxic preventative therapies, with ongoing cases of Bovine Spongiform Encephalopathy (BSE) and the spread of Chronic Wasting Disease (CWD). Within the realm of chemotherapeutic approaches, much research has focussed on blocking the conversion of the normal form of prion protein (PrP(c)) to its abnormal counterpart (PrP(res)). Structurally, these chemotherapeutic agents are often polyanionic or polycyclic and may directly bind PrP(c) or PrP(res), or act by redistributing, sequestering, or down-regulating PrP(c), thus preventing its conversion. There are also some polycationic compounds which proport to enhance the clearance of PrP(res). Other targets include accessory molecules such as the laminin receptor precursor which influences conversion, or cell signalling molecules which may be required for pathogenesis. Of recent interest are the possible neuroprotective effects of some drugs. Importantly, there is evidence that combining compounds may provide synergistic responses. This review provides an update on current testing methods, therapeutic targets, and promising candidates for chemical-based therapy.
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Affiliation(s)
- Valerie L Sim
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
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21
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Hoyer D, Thakker DR, Natt F, Maier R, Huesken D, Müller M, Flor P, VAN DER Putten H, Schmutz M, Bilbe G, Cryan JF. Global Down-Regulation of Gene Expression in the Brain Using RNA Interference, with Emphasis on Monoamine Transporters and GPCRs: Implications for Target Characterization in Psychiatric and Neurological Disorders. J Recept Signal Transduct Res 2008; 26:527-47. [PMID: 17118797 DOI: 10.1080/10799890600929663] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
RNA interference (RNAi) is a natural mechanism for regulating gene expression, which exists in plants, invertebrates, and mammals. We investigated whether non-viral infusion of short interfering RNA (siRNA) by the intracerebroventricular route would enable a sequence-specific gene knockdown in the mouse brain and whether the knockdown translates into disease-relevant behavioral changes. Initially, we targeted enhanced green fluorescent protein (EGFP) in mice overexpressing EGFP. A selective knockdown of both EGFP protein and mRNA was observed throughout the brain, with lesser down-regulation in regions distal to the infusion site. We then targeted endogenous genes, encoding the dopamine (DAT) and serotonin transporters (SERT). DAT-siRNA infusion in adult mice produced a significant down-regulation of DAT mRNA and protein and elicited hyperlocomotion similar, but delayed, to that produced on infusion of GBR-12909, a potent and selective DAT inhibitor. Similarly, SERT-siRNA infusion resulted in significant knockdown of SERT mRNA and protein and elicited reduced immobility in the forced swim test similar to that obtained on infusion of citalopram, a very selective and potent SSRI. Application of this non-viral RNAi approach may accelerate target validation for neuropsychiatric disorders that involve a complex interplay of gene(s) from various brain regions.
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Affiliation(s)
- Daniel Hoyer
- Psychiatry Program, Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, Basel, Switzerland.
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Gilch S, Krammer C, Schätzl HM. Targeting prion proteins in neurodegenerative disease. Expert Opin Biol Ther 2008; 8:923-40. [PMID: 18549323 DOI: 10.1517/14712598.8.7.923] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Spongiform neurodegeneration is the pathological hallmark of individuals suffering from prion disease. These disorders, whose manifestation is sporadic, familial or acquired by infection, are caused by accumulation of the aberrantly folded isoform of the cellular prion protein (PrP(c)), termed PrP(Sc). Although usually rare, prion disorders are inevitably fatal and transferrable by infection. OBJECTIVE Pathology is restricted to the central nervous system and premortem diagnosis is usually not possible. Yet, promising approaches towards developing therapeutic regimens have been made recently. METHODS The biology of prion proteins and current models of neurotoxicity are discussed and prophylactic and therapeutic concepts are introduced. RESULTS/CONCLUSIONS Although various promising drug candidates with antiprion activity have been identified, this proof-of-concept cannot be transferred into translational medicine yet.
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Affiliation(s)
- Sabine Gilch
- Technische Universität München, Institute of Virology, Prion Research Group, Trogerstreet 30, 81675 Munich, Germany
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23
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Single treatment with RNAi against prion protein rescues early neuronal dysfunction and prolongs survival in mice with prion disease. Proc Natl Acad Sci U S A 2008; 105:10238-43. [PMID: 18632556 DOI: 10.1073/pnas.0802759105] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Prion diseases are fatal neurodegenerative conditions for which there is no effective treatment. Prion propagation involves the conversion of cellular prion protein, PrP(C), to its conformational isomer, PrP(Sc), which accumulates in disease. Here, we show effective therapeutic knockdown of PrP(C) expression using RNAi in mice with established prion disease. A single administration of lentivirus expressing a shRNA targeting PrP into each hippocampus of mice with established prion disease significantly prolonged survival time. Treated animals lived 19% and 24% longer than mice given an "empty" lentivirus, or not treated, respectively. Lentivirally mediated RNAi of PrP also prevented the onset of behavioral deficits associated with early prion disease, reduced spongiform degeneration, and protected against neuronal loss. In contrast, mice receiving empty virus or no treatment developed early cognitive impairment and showed severe spongiosis and neuronal loss. The focal use of RNAi therapeutically in prion disease further supports strategies depleting PrP(C), which we previously established to be a valid target for prion-based treatments. This approach can now be used to define the temporal, quantitative, and regional requirements for PrP knockdown for effective treatment of prion disease and to explore mechanisms involved in predegenerative neuronal dysfunction and its rescue.
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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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Prnp knockdown in transgenic mice using RNA interference. Transgenic Res 2008; 17:783-91. [PMID: 18350371 DOI: 10.1007/s11248-008-9179-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 02/25/2008] [Indexed: 10/22/2022]
Abstract
RNA interference has become a widely used approach to perform gene knockdown experiments in cell cultures and more recently transgenic animals. A designed miRNA targeting the prion protein mRNA was built and expressed using the human PRNP promoter. Its efficiency was confirmed in transfected cells and it was used to generate several transgenic mouse lines. Although expressed at low levels, it was found to downregulate the endogenous mouse Prnp gene expression to an extent that appears to be directly related with the transgene expression level and that could reach up to 80% inhibition. This result highlights the potential and limitations of the RNA interference approach when applied to disease resistance.
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26
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Lu W, Wang J, Wen T. Downregulation of Rho-GDI gamma promotes differentiation of neural stem cells. Mol Cell Biochem 2008; 311:233-40. [PMID: 18273563 DOI: 10.1007/s11010-008-9713-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2007] [Accepted: 01/29/2008] [Indexed: 11/28/2022]
Abstract
Rho-GDIgamma belongs to the Rho-GDI protein family, which was observed to have high level expression in the entire brain. Although it exists in neuronal population, its physiological function is poorly understood. This study shows that Rho-GDIgamma is a key factor in the G13 signaling pathway based on an analysis of global gene expression. By using RNAi technology to downregulate expression of Rho-GDIgamma we found distinct morphological changes in neural stem cell line C17.2. More important, RT-PCR confirmed that RNAi-mediated downregulation of Rho-GDIgamma decreased expression of Rho-GDIgamma-regulated genes RhoA, Cdc42, Limk2, and N-WASP and slightly increased expression of Rac1. Further, immunochemical staining indicated that downregulation of Rho-GDIgamma increased the tendency of C17.2 cells to differentiate. These data strongly suggest that Rho-GDIgamma plays a key role in the differentiation of neural stem cells.
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Affiliation(s)
- Wei Lu
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, 99 Shang Da Road, Shanghai 200444, China
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28
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Abstract
The biological role of the scrapie isoform of prion protein (PrP(Sc)) as an infectious agent in numerous human and non-human disorders of the central nervous system is well established. In contrast, and despite decades of intensive research, the physiological function of the endogenous cellular form of the prion protein (PrP(C)) remains elusive. In mammals, the ubiquitous expression of PrP(C) suggests biological functions other than its pathological role in propagating the accumulation of its misfolded isotype. Other functions that have been attributed to PrP(C) include signal transduction, synaptic transmission and protection against cell death through the apoptotic pathway. More recently, immunoregulatory properties of PrP(C) have been reported. We review accumulating in vitro and in vivo evidence regarding physiological functions of PrP(C).
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Affiliation(s)
- W Hu
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Dallas, TX 75390-9036, USA
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29
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Pfeifer A. Therapeutic potential of RNA interference in neurodegenerative diseases. FUTURE NEUROLOGY 2007. [DOI: 10.2217/14796708.2.3.237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Alexander Pfeifer
- Institute of Pharmacology & Toxicology, University of Bonn, Reuterstr. 2B, Germany
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30
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Federici T, Boulis NM. Ribonucleic acid interference for neurological disorders: candidate diseases, potential targets, and current approaches. Neurosurgery 2007; 60:3-15; discussion 15-6. [PMID: 17228249 DOI: 10.1227/01.neu.0000249214.42461.a5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
OBJECTIVE Ribonucleic acid (RNA) interference (RNAi) is a conserved evolutionary defense mechanism that is gaining utility for therapeutic application by modulating gene expression or silencing disease-causing genes. METHODS This strategy has recently achieved success in mammalian cells via synthetic small interfering RNA or short hairpin RNA expressed in vectors for gene delivery. The vector-based RNAi strategy has particular potential because of the possibility of targeted gene delivery, long-term gene expression, and the potential means of penetrating the blood-brain barrier. RESULTS RNAi-based approaches have been proposed for a variety of neurological disorders, including dominant genetic diseases, neurodegenerative diseases, malignant brain tumors, pain, and viral-induced encephalopathies. CONCLUSION This review summarizes the current approaches of the RNAi strategy for neurological disorders, focusing on potential targets for therapeutic intervention.
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Affiliation(s)
- Thais Federici
- Department of Neuroscience The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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31
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Pfeifer A, Eigenbrod S, Al-Khadra S, Hofmann A, Mitteregger G, Moser M, Bertsch U, Kretzschmar H. Lentivector-mediated RNAi efficiently suppresses prion protein and prolongs survival of scrapie-infected mice. J Clin Invest 2007; 116:3204-10. [PMID: 17143329 PMCID: PMC1679709 DOI: 10.1172/jci29236] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Accepted: 08/29/2006] [Indexed: 01/16/2023] Open
Abstract
Prion diseases are fatal neurodegenerative diseases characterized by the accumulation of PrP(Sc), the infectious and protease-resistant form of the cellular prion protein (PrP(C)). We generated lentivectors expressing PrP(C)-specific short hairpin RNAs (shRNAs) that efficiently silenced expression of the prion protein gene (Prnp) in primary neuronal cells. Treatment of scrapie-infected neuronal cells with these lentivectors resulted in an efficient and stable suppression of PrP(Sc) accumulation. After intracranial injection, lentiviral shRNA reduced PrP(C) expression in transgenic mice carrying multiple copies of Prnp. To test the therapeutic potential of lentiviral shRNA, we used what we believe to be a novel approach in which the clinical situation was mimicked. We generated chimeric mice derived from lentivector-transduced embryonic stem cells. Depending on the degree of chimerism, these animals carried the lentiviral shRNAs in a certain percentage of brain cells and expressed reduced levels of PrP(C). Importantly, in highly chimeric mice, survival after scrapie infection was significantly extended. Taken together, these data suggest that lentivector-mediated RNA interference could be an approach for the treatment of prion disease.
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Affiliation(s)
- Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
| | - Sabina Eigenbrod
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
| | - Saba Al-Khadra
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
| | - Andreas Hofmann
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
| | - Gerda Mitteregger
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
| | - Markus Moser
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
| | - Uwe Bertsch
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
| | - Hans Kretzschmar
- Institute of Pharmacology and Toxicology, University of Bonn, Bonn, Germany.
Molecular Pharmacology, Department of Pharmacy, and
Center for Neuropathology and Prion Research, Ludwig-Maximilians-University of Munich, Munich, Germany.
Max Planck Institute of Biochemistry, Molecular Medicine, Martinsried, Germany
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Zhang Y, Qin K, Wang J, Hung T, Zhao RY. Dividing roles of prion protein in staurosporine-mediated apoptosis. Biochem Biophys Res Commun 2006; 349:759-68. [PMID: 16950206 DOI: 10.1016/j.bbrc.2006.08.116] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Accepted: 08/17/2006] [Indexed: 11/24/2022]
Abstract
Prion protein (PrPC) is a normal cellular glycoprotein that is expressed in almost all tissues including the central nervous system. Much attention has been focused on this protein because conversion of the normal PrPC to the diseased form (PrPSc) plays an essential role in transmissible spongiform encephalopathies such as mad cow disease and Creutzfeldt-Jakob disease. In spite of the extensive effort, the normal physiological function of PrPC remains elusive. Emerging evidence suggests that PrPC plays a protective role against cellular stresses including apoptosis induced by various pro-apoptotic agents such as Bax and staurosporine (STS), however, other reports showed overexpression of PrPC enhances STS-mediated apoptosis. In this study, we took a different approach by depleting endogenous PrPC using specific interfering RNA technique and compared the depleting and overproducing effects of PrPC on STS-induced apoptosis in neuro-2a (N2a) cells. We demonstrate here that down-regulation of PrPC sensitizes N2a cells to STS-induced cytotoxicity and apoptosis. The enhanced apoptosis induced by STS was shown by increased DNA fragmentation, immunoreactivity of Bax, and caspase-3 cleavage. We also showed that overproduction of PrPC had little or no effect on STS-mediated DNA fragmentation in N2a cells but it augments STS-mediated apoptosis in HEK293 cells, suggesting a cell line-specific effect. In addition, the inhibitory effect of PrPC on STS-mediated cellular stress appears to be modulated in part through induction of cell cycle G2 accumulation. Together, our data suggest that physiological level of endogenous PrPC plays a protective role against STS-mediated cellular stress. Loss of this protection could render cells more prone to cellular insults such as STS.
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Affiliation(s)
- Ying Zhang
- Institute of Basic Medical Sciences, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100005, People's Republic of China
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Zawlik I, Witusik M, Hulas-Bigoszewska K, Piaskowski S, Szybka M, Golanska E, Liberski PP, Rieske P. Regulation of PrPC expression: Nerve growth factor (NGF) activates the prion gene promoter through the MEK1 pathway in PC12 cells. Neurosci Lett 2006; 400:58-62. [PMID: 16520000 DOI: 10.1016/j.neulet.2006.02.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/12/2006] [Accepted: 02/05/2006] [Indexed: 10/24/2022]
Abstract
A high expression of PrP(C) in cells is one factor that increases the risk of conversion to the misfolded, disease-associated form (PrP(Sc)) characteristic of transmissible spongiform encephalopathies. Thus, developing a method to control the level of PrP(C) expression in cells could be one way to delay or prevent the onset of clinical signs of these diseases. In this study the mechanisms controlling the expression of the Prnp gene in PC12 cells and in rat brain were examined. We observed a slight activation of a cloned fragment of the human PRNP gene promoter using the luciferase reporter system in PC12 cells stimulated with nerve growth factor (NGF). The activating effect of NGF was enhanced by mitogen-activated protein kinase (MEK1) and suppressed by myristylated serine/threonine kinase (myrAKT). These results suggest that MEK1 is a positive activator of the PRNP promoter that inhibits the AKT pathway. Independent experiments suggested that high expression of PrP(C) in the brain depends on the rate of translation and/or the efficiency of PrP(C) stabilization. We also investigated the epigenic status of the Prnp promoter. We observed no increase of PrP(C) or Prnp mRNA levels in PC12 cells after treatment with the DNA-demethylating agent. The Prnp promoter did not display methylation either in NGF-treated and untreated PC12 cells, or in the rat brain. These results improve the understanding of the regulation of the Prnp gene promoter, a DNA regulatory element controlling the expression of PrP(C), a protein involved in several neurological diseases.
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Affiliation(s)
- Izabela Zawlik
- Department of Molecular Pathology and Neuropathology, Chair of Oncology, Medical University of Lodz, 8/10 Czechoslowacka str., 92-216 Lodz, Poland
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Golding MC, Long CR, Carmell MA, Hannon GJ, Westhusin ME. Suppression of prion protein in livestock by RNA interference. Proc Natl Acad Sci U S A 2006; 103:5285-90. [PMID: 16567624 PMCID: PMC1459347 DOI: 10.1073/pnas.0600813103] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Given the difficulty of applying gene knockout technology to species other than mice, we decided to explore the utility of RNA interference (RNAi) in silencing the expression of genes in livestock. Short hairpin RNAs (shRNAs) were designed and screened for their ability to suppress the expression of caprine and bovine prion protein (PrP). Lentiviral vectors were used to deliver a transgene expressing GFP and an shRNA targeting PrP into goat fibroblasts. These cells were then used for nuclear transplantation to produce a cloned goat fetus, which was surgically recovered at 81 days of gestation and compared with an age-matched control derived by natural mating. All tissues examined in the cloned fetus expressed GFP, and PCR analysis confirmed the presence of the transgene encoding the PrP shRNA. Most relevant, Western blot analysis performed on brain tissues comparing the transgenic fetus with control demonstrated a significant (>90%) decrease in PrP expression levels. To confirm that similar methodologies could be applied to the bovine, recombinant virus was injected into the perivitelline space of bovine ova. After in vitro fertilization and culture, 76% of the blastocysts exhibited GFP expression, indicative that they expressed shRNAs targeting PrP. Our results provide strong evidence that the approach described here will be useful in producing transgenic livestock conferring potential disease resistance and provide an effective strategy for suppressing gene expression in a variety of large-animal models.
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Affiliation(s)
- Michael C. Golding
- *Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Howard Hughes Medical Institute, 1 Bungtown Road, Cold Spring Harbor, NY 11724; and
| | - Charles R. Long
- Department of Veterinary Physiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843
| | - Michelle A. Carmell
- *Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Howard Hughes Medical Institute, 1 Bungtown Road, Cold Spring Harbor, NY 11724; and
| | - Gregory J. Hannon
- *Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Howard Hughes Medical Institute, 1 Bungtown Road, Cold Spring Harbor, NY 11724; and
- To whom correspondence may be addressed. E-mail:
| | - Mark E. Westhusin
- Department of Veterinary Physiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843
- To whom correspondence may be addressed. E-mail:
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Nordström EK, Luhr KM, Ibáñez C, Kristensson K. Inhibitors of the mitogen-activated protein kinase kinase 1/2 signaling pathway clear prion-infected cells from PrPSc. J Neurosci 2006; 25:8451-6. [PMID: 16162927 PMCID: PMC6725673 DOI: 10.1523/jneurosci.2349-05.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Prions represent a unique class of infectious agents in which the normal cellular prion protein (PrPC) is converted to an abnormal isoform (PrPSc), which accumulates in the brain and constitutes the major, if not the only, component of the infectious particle. Factors that still remain to be identified may facilitate the conversion of PrPC to PrPSc. In the present study, we first demonstrated that a growth factor of the neurotrophin family, brain-derived neurotrophic factor (BDNF), stimulates the formation of PrPSc in a gonadotropin-releasing hormone-secreting neuronal cell line (GT1-1 cells) infected with the Rocky Mountain Laboratory (RML) strain of scrapie as determined by Western blot analysis. We then observed that the prion-infected cells can be cleared from PrPSc by treatment with three inhibitors of mitogen-activated protein kinase kinase 1/2 (MEK1/2) [1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercapto)butadiene and 2-(2-amino-3-methyoxyphenyl)-4H-1-benzopyran-4-one, as well as alpha-[amino[(4-aminophenyl)thio]methylene]-2-(trifluoromethyl) benzeneacetonitrile, which passes the blood-brain barrier], a component of one of the intracellular signaling pathways activated by BDNF. The MEK1/2 inhibitors were also efficient in clearing PrPSc from prion-infected GT1-1 cells stimulated to accumulate high levels of PrPSc by enhanced serum concentrations in the medium or by the use of a serum-free neuron-specific neurobasal medium. PrPSc did not reappear in the cultures within 5 weeks after completion of treatment. We conclude that inhibitors of the MEK1/2 pathway can efficiently and probably irreversibly clear PrP(Sc) from prion-infected cells. The MEK pathway may therefore be a suitable target for therapeutic intervention in prion diseases.
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Affiliation(s)
- Elin K Nordström
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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Lee SH, Sinko PJ. siRNA--getting the message out. Eur J Pharm Sci 2006; 27:401-10. [PMID: 16442784 DOI: 10.1016/j.ejps.2005.12.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 11/26/2005] [Accepted: 12/04/2005] [Indexed: 12/27/2022]
Abstract
The recent observation that potent and sequence-specific gene silencing by injection of double-stranded RNA (dsRNA) has sparked the phenomenon known as "RNA interference" (RNAi) and has enabled the gene-specific knockdown of drug transport proteins and metabolizing enzymes. The application of small interfering RNAs (siRNAs) is broad and the potential for use as research tools is now well established in vitro. In vivo use is still a challenge that is primarily focused on the difficulty of delivering siRNAs to target cells. The potential use of siRNAs as therapeutic agents is also exciting and holds great promise for future. For the study of drug transporter function in absorption, distribution, metabolism and excretion (ADME) and in the treatment of diseases, siRNA offers a way to gather interpretable mechanistic data-a distinct advantage over the use of "specific" chemical inhibitors. This mini review provides background information on siRNA as well as examples of the use of siRNA as applied to drug transporters.
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Affiliation(s)
- S H Lee
- Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ 08854, USA
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Qin K, Zhao L, Tang Y, Bhatta S, Simard JM, Zhao RY. Doppel-induced apoptosis and counteraction by cellular prion protein in neuroblastoma and astrocytes. Neuroscience 2006; 141:1375-88. [PMID: 16766127 DOI: 10.1016/j.neuroscience.2006.04.068] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 04/18/2006] [Accepted: 04/19/2006] [Indexed: 01/05/2023]
Abstract
Expression of a prion-like protein, doppel, induces apoptosis-like changes in cerebellar neuronal granule and Purkinje cells of prion-knockout mice and this effect can be rescued by re-introduction of cellular prion. Since most of those studies were done in transgenic mice, in the present study, we have established a murine neuro-2a cell line and the primary rat adult reactive astrocyte model for studying doppel-induced apoptosis and possible prion counteraction. We demonstrate that expression of doppel in neuro-2a cells causes apoptosis, during which DNA fragmentation occurs as visualized by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling staining and other intracellular changes characteristic of apoptosis are observed in the electron microscope. Using immunoblot analyses, we further demonstrate that doppel expression activates caspase-10 as well as caspase-3, but does not activate caspase-9. Addition of purified doppel to cultures of neuro-2a cells and the primary astrocytes causes similar apoptotic changes. Significantly, apoptosis induced by doppel is enhanced when cellular prion protein is depleted by RNA interference, suggesting a protective effect of cellular prion against doppel-induced apoptosis. The antagonistic interaction between cellular prion and doppel appears to involve direct protein-protein interaction possibly on cell membrane as cellular prion and doppel physically interact with each other and co-localize on cell membranes. Together, our data show that doppel induces apoptosis in neuroblastoma neuro-2a and rat primary astrocytes via a caspase-10 mediated pathway and that this effect is counteracted by cellular prion through direct interaction with doppel possibly on cell membrane.
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Affiliation(s)
- K Qin
- Department of Pathology, University of Maryland School of Medicine, 10 South Pine Street, MSTF 700A, Baltimore, MD 21201, USA
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Thakker DR, Hoyer D, Cryan JF. Interfering with the brain: use of RNA interference for understanding the pathophysiology of psychiatric and neurological disorders. Pharmacol Ther 2005; 109:413-38. [PMID: 16183135 DOI: 10.1016/j.pharmthera.2005.08.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Accepted: 08/03/2005] [Indexed: 12/31/2022]
Abstract
Psychiatric and neurological disorders are among the most complex, poorly understood, and debilitating diseases in medicine. The burgeoning advances in functional genomic technologies have led to the identification of a vast number of novel genes that are potentially implicated in the pathophysiology of such disorders. However, many of these candidate genes have not yet been functionalized and require validation in vivo. Traditionally, abrogating gene function is one of the primary means of examining the physiological significance of a given gene product. Several methods have been developed for gene ablation or knockdown, however, with limited levels of success. The recent discovery of RNA interference (RNAi), as a highly efficient method for gene knockdown, has been one of the major breakthroughs in molecular medicine. In vivo application of RNAi is further demonstrating the promise of this technology. Recent efforts have focused on applying RNAi-based knockdown to understand the genes implicated in neuropsychiatric disorders. However, the greatest challenge with this approach is translating the success of RNAi from mammalian cell cultures to the brain in animal models of disease and, subsequently, in patients. In this review, we describe the various methods that are being developed to deliver RNAi into the brain for down-regulating gene expression and subsequent phenotyping of genes in vivo. We illustrate the utility of various approaches with a few successful examples and also discuss the potential benefits and pitfalls associated with the use of each delivery approach. Appropriate tailoring of tools that deliver RNAi in the brain may not only aid our understanding of the complex pathophysiology of neuropsychiatric disorders, but may also serve as a valuable therapy for disorders, where there is an immense unmet medical need.
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Affiliation(s)
- Deepak R Thakker
- Psychiatry Program, Neuroscience Research, Novartis Institutes for BioMedical Research, Novartis Pharma AG, Basel, Switzerland
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Safar JG, Kellings K, Serban A, Groth D, Cleaver JE, Prusiner SB, Riesner D. Search for a prion-specific nucleic acid. J Virol 2005; 79:10796-806. [PMID: 16051871 PMCID: PMC1182634 DOI: 10.1128/jvi.79.16.10796-10806.2005] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diversity of prion strains was attributed to an elusive nucleic acid, yet a search spanning nearly two decades has failed to identify a prion-specific polynucleotide. In our search for a prion-specific nucleic acid, we analyzed nucleic acids in purified fractions from the brains of Syrian hamsters infected with Sc237 prions. Purification of Sc237 prions removed nucleic acids larger than 50 nucleotides as measured by return refocusing electrophoresis (RRGE). To determine the size of the largest polynucleotide present in purified fractions at an abundance of one molecule per infectious (ID50) unit, we measured prions present after inoculation. In order to account for the rapid clearance of prions after intracerebral inoculation, we determined the number of PrP(Sc) molecules and ID50 units of prions that were retained in brain. Factoring in clearance after inoculation, we estimate that the largest polynucleotide present in our purified fractions at one molecule per ID50 unit is approximately 25 nucleotides in length. In the same fractions, there were approximately 3,000 protease-resistant PrP(Sc) molecules per ID50 unit after accounting for clearance of PrP(Sc) following inoculation. We compared the resistance of Sc237 and 139H prions to inactivation by UV irradiation at 254 nm. Irradiation of homogenates and microsomes diminished prion infectivity by a factor of approximately 1,000 but did not alter the strain-specified properties of the Sc237 and 139H prions. The data reported here combined with the production of synthetic prions argue that the 25-mer polynucleotides found in purified prion preparations are likely to be host encoded and of variable sequence; additionally, these 25-mers are unlikely to be prion specific.
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Affiliation(s)
- Jiri G Safar
- Institute for Neurodegenerative Diseases, University of California, San Francisco 94143-0518, USA
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Zhao N, Zu ZX, Liu CM, Dong WJ, Liu DP, Liang CC. Knockdown of mouse adult beta-globin gene expression in MEL cells by retrovirus vector-mediated RNA interference. Mol Biotechnol 2005; 28:195-9. [PMID: 15542920 DOI: 10.1385/mb:28:3:195] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
RNA interference (RNAi) efficiently induces sequence-specific gene silencing in mammalian cells through short interfering RNA (siRNA) of 21-23 nucleotides synthesized in vitro or expressed by DNA-based vector. However, introduction of siRNA into mammalian cells by transfection limits the application of RNAi, especially when it is necessary to generate long-term gene silencing in vivo. Virus vector-mediated RNAi provides an alternative to transfection. In the present study, we investigated such transduction system and showed that retrovirus vector-mediated RNAi can substantially down-regulate expression of mouse adult beta-globin gene in MEL cells. The results suggest that retrovirus vector-delivered RNAi may find its use in functional genomics and in gene therapy.
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Affiliation(s)
- Na Zhao
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College (CAMS & PUMC), 5 Dong Dan San Tiao, Beijing 100005, PR China
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Abstract
RNA interference (RNAi) is an adaptive defense mechanism triggered by double-stranded RNA (dsRNA). It is a powerful reverse genetic tool that has been widely employed to silence gene expression in mammalian and human cells. RNAi-based gene therapies, especially in viral diseases have become more and more interesting and promising. Recently, small interfering RNA (siRNA) can be used to protect host from viral infection, inhibit the expression of viral antigen and accessory genes, control the transcription and replication of viral genome, hinder the assembly of viral particles, and display influences in virus-host interactions. In this review, we attempt to present recent progresses of this breakthrough technology in the above fields and summarize the possibilities of siRNA-based drugs.
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Affiliation(s)
- Fischer L TAN
- Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101 China
| | - James Q YIN
- Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101 China
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Dillon CP, Sandy P, Nencioni A, Kissler S, Rubinson DA, Van Parijs L. Rnai as an experimental and therapeutic tool to study and regulate physiological and disease processes. Annu Rev Physiol 2005; 67:147-73. [PMID: 15709955 DOI: 10.1146/annurev.physiol.67.040403.130716] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Over the past four years RNA interference (RNAi) has exploded onto the research scene as a new approach to manipulate gene expression in mammalian systems. More recently, RNAi has garnered much interest as a potential therapeutic strategy. In this review, we briefly summarize the current understanding of RNAi biology and examine how RNAi has been used to study the genetic basis of physiological and disease processes in mammalian systems. We also explore some of the new developments in the use of RNAi for disease therapy and highlight the key challenges that currently limit its application in the laboratory, as well as in the clinical setting.
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Affiliation(s)
- Christopher P Dillon
- Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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Abstract
PURPOSE OF REVIEW Prion diseases are transmissible fatal neurodegenerative disorders in which infectivity is associated with the accumulation of PrP(Sc), a disease-related isoform of normal cellular prion protein. The recent emergence of variant Creutzfeldt-Jakob disease has led to major public health concerns, and the need for the development of effective treatments. As PrP(Sc) is associated both with pathology and infectivity, therapeutic approaches to date have largely aimed at preventing its accumulation, but this strategy has produced only modest results in animal models. The link between PrP(Sc) and neurotoxicity is unclear, and alternative pathological processes need to be considered. Here we focus on the latest progress in therapeutic strategies and potential mechanisms of prion neurotoxicity. RECENT FINDINGS Passive immunisation with anti-prion protein antibodies prevents peripheral prion replication and blocks progression to clinical disease in peripherally infected mice. A new approach, in which neuronal cellular prion protein is depleted in mice with established neuroinvasive prion infection, prevents the onset of clinical disease, blocks neuronal cell loss and reverses early spongiform pathology. This dramatic protective effect occurs despite the continued build-up of extraneuronal PrP(Sc) and continued replication of prion infectivity, effectively producing a sub-clinical state. SUMMARY New insights into the mechanisms of neurotoxicity in prion diseases support the concept that PrP(Sc) itself is not directly neurotoxic. They suggest that neuronal prion propagation results in the production of a toxic intermediate or depletion of a key constituent. Prevention of the formation of such a species rather than PrP(Sc) accumulation itself is a clear target for prion therapeutics.
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Affiliation(s)
- Giovanna Mallucci
- MRC Prion Unit and Department of Neurodegenerative Disease, Institute of Neurology, National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
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Abstract
Prions--pathogens that are lethal to humans and other animals--are thought to be conformational isomers of the cellular prion protein. Their unique biology, and the potential for a wider pathobiological significance of prion-like mechanisms, has motivated much research into understanding prion neurodegeneration. Moreover, concerns that extensive dietary exposure to bovine spongiform encephalopathy (BSE) prions might have infected many individuals--who might eventually develop its human counterpart, variant Creutzfeldt-Jakob disease (vCJD)--has focused much interest on therapeutics. The challenge of interrupting this aggressive, diffuse and uniformly fatal neurodegenerative process is daunting. However, the recent finding that the onset of clinical disease in established neuroinvasive prion infection in a mouse model can be halted and early pathology reversed is a source for considerable optimism. A therapeutic focus on the cellular prion protein, rather than prions themselves, which might not be directly neurotoxic, is suggested.
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Affiliation(s)
- Giovanna Mallucci
- Medical Research Council Prion Unit and Department of Neurodegenerative Disease, Institute of Neurology, University College London, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
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45
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Abstract
One of the most exciting findings in recent years has been the discovery of RNA interference (RNAi). RNAi is an important system that allows sequence-specific gene silencing through targeted degradation of mRNA by cognate double-stranded RNA (dsRNA). RNAi plays a role in endogenous cellular processes, such as developmental control and heterochromatin formation, and serves as an antiviral defense mechanism. Recent findings suggest that RNAi and related pathways are involved in protecting the genome against instabilities caused by transposons and repetitive sequences. Several rapidly developing RNAi methodologies provide a new approach for elucidation of gene functions. RNAi technology is also currently being evaluated as a potentially useful method to develop highly specific dsRNA-based gene-silencing therapeutics. In this paper, we review the use of RNAi in neuroscience research and as a possible therapeutic tool for treatment of neurological diseases.
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Affiliation(s)
- Sermin Genc
- Department of Medical Biology and Genetics, School of Medicine, Dokuz Eylul University, Inciralti, 35340 Izmir, Turkey.
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Ertmer A, Gilch S, Yun SW, Flechsig E, Klebl B, Stein-Gerlach M, Klein MA, Schätzl HM. The tyrosine kinase inhibitor STI571 induces cellular clearance of PrPSc in prion-infected cells. J Biol Chem 2004; 279:41918-27. [PMID: 15247213 DOI: 10.1074/jbc.m405652200] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The conversion of the cellular prion protein (PrP(c)) into pathologic PrP(Sc) and the accumulation of aggregated PrP(Sc) are hallmarks of prion diseases. A variety of experimental approaches to interfere with prion conversion have been reported. Our interest was whether interference with intracellular signaling events has an impact on this conversion process. We screened approximately 50 prototype inhibitors of specific signaling pathways in prion-infected cells for their capacity to affect prion conversion. The tyrosine kinase inhibitor STI571 was highly effective against PrP(Sc) propagation, with an IC(50) of < or =1 microM. STI571 cleared prion-infected cells in a time- and dose-dependent manner from PrP(Sc) without influencing biogenesis, localization, or biochemical features of PrP(c). Interestingly, this compound did not interfere with the de novo formation of PrP(Sc) but activated the lysosomal degradation of pre-existing PrP(Sc), lowering the half-life of PrP(Sc) from > or =24 h to <9 h. Our data indicate that among the kinases known to be inhibited by STI571, c-Abl is likely responsible for the observed anti-prion effect. Taken together, we demonstrate that treatment with STI571 strongly activates the lysosomal degradation of PrP(Sc) and that substances specifically interfering with cellular signaling pathways might represent a novel class of anti-prion compounds.
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Affiliation(s)
- Alexa Ertmer
- Institute of Virology, Prion Research Group, Technical University of Munich, Biedersteiner Strasse 29, D-80802 Munich, Germany
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Tremolizzo L, Rodriguez-Menendez V, Ferrarese C. On scrapie interference and artificial prions. Med Hypotheses 2004; 63:838-40. [PMID: 15488657 DOI: 10.1016/j.mehy.2004.02.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2004] [Accepted: 02/15/2004] [Indexed: 10/26/2022]
Abstract
The mechanisms responsible for neuronal death in transmissible spongiform encephalopathies (TSEs) are still not completely understood, and at least two major hypotheses have been formulated, based on the peculiar aspects of prion protein biology. In fact, the neuronal spreading of the prion conformational change may lead either to gain toxic properties, or to loose the normal function of this protein. In order to investigate the relative contribution of these two opposite mechanisms, two theoretical approaches may be proposed: RNA interference (RNAi) and artificial prion engineering. In fact, RNAi techniques offer now an extremely exciting new tool for investigating the effects of gene silencing both in prion, and other neurological disorders. On the other hand, the gain-of-toxic-function hypothesis might be definitely evaluated by creating an artificial prion choosing a protein target whose loss of function could be bypassed in the experimental set. In this paper the two aforementioned strategies are outlined, briefly discussing the consequent implications for TSE therapy.
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Affiliation(s)
- Lucio Tremolizzo
- Laboratory of Neurobiology, D.N.T.B., University of Milano-Bicocca, S.Gerardo Hospital, Villa Serena 4 p. Sud, via Donizetti 106, 20052 Monza (MI), Italy.
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Wood MJA, Trülzsch B, Abdelgany A, Beeson D. Therapeutic gene silencing in the nervous system. Hum Mol Genet 2003; 12 Spec No 2:R279-84. [PMID: 12928477 DOI: 10.1093/hmg/ddg275] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Progress in the understanding of RNA biology has brought into focus the prospect of using RNA-based therapeutics as a novel approach to treat human disease. In particular, following the discovery of the RNA interference (RNAi) pathway, the emergence of technology based on small interfering RNA (siRNA) now offers a powerful and highly specific tool for therapeutic gene silencing. Many neurological diseases, including neurodegenerative disorders, tumours and retinal disease are likely candidates to benefit from such advances. The challenges ahead will be to identify appropriate disease gene targets and, crucially, to understand the biological parameters that determine safe, precise and effective delivery and function of RNA-based therapeutic molecules within the unique environment of the nervous system.
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Affiliation(s)
- Matthew J A Wood
- Department of Human Anatomy and Genetics, Oxford University, Oxford, UK.
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