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Jideonwo V, Hou Y, Ahn M, Surendran S, Morral N. Impact of silencing hepatic SREBP-1 on insulin signaling. PLoS One 2018; 13:e0196704. [PMID: 29723221 PMCID: PMC5933792 DOI: 10.1371/journal.pone.0196704] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 04/18/2018] [Indexed: 11/18/2022] Open
Abstract
Sterol Regulatory Element Binding Protein-1 (SREBP-1) is a conserved transcription factor of the basic helix-loop-helix leucine zipper family (bHLH-Zip) that plays a central role in regulating expression of genes of carbohydrate and fatty acid metabolism in the liver. SREBP-1 activity is essential for the control of insulin-induced anabolic processes during the fed state. In addition, SREBP-1 regulates expression of key molecules in the insulin signaling pathway, including insulin receptor substrate 2 (IRS2) and a subunit of the phosphatidylinositol 3-kinase (PI3K) complex, PIK3R3, suggesting that feedback mechanisms exist between SREBP-1 and this pathway. Nevertheless, the overall contribution of SREBP-1 activity to maintain insulin signal transduction is unknown. Furthermore, Akt is a known activator of mTORC1, a sensor of energy availability that plays a fundamental role in metabolism, cellular growth and survival. We have silenced SREBP-1 and explored the impact on insulin signaling and mTOR in mice under fed, fasted and refed conditions. No alterations in circulating levels of insulin were observed. The studies revealed that depletion of SREBP-1 had no impact on IRS1Y612, AktS473, and downstream effectors GSK3αS21 and FoxO1S256 during the fed state. Nevertheless, reduced levels of these molecules were observed under fasting conditions. These effects were not associated with changes in phosphorylation of mTOR. Overall, our data indicate that the contribution of SREBP-1 to maintain insulin signal transduction in liver is modest.
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Affiliation(s)
- Victoria Jideonwo
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Yongyong Hou
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Miwon Ahn
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Sneha Surendran
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Núria Morral
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- * E-mail:
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Moore NA, Bracha P, Hussain RM, Morral N, Ciulla TA. Gene therapy for age-related macular degeneration. Expert Opin Biol Ther 2017; 17:1235-1244. [PMID: 28726562 DOI: 10.1080/14712598.2017.1356817] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION In neovascular age related macular degeneration (nAMD), gene therapy to chronically express anti-vascular endothelial growth factor (VEGF) proteins could ameliorate the treatment burden of chronic intravitreal therapy and improve limited visual outcomes associated with 'real world' undertreatment. Areas covered: In this review, the authors assess the evolution of gene therapy for AMD. Adeno-associated virus (AAV) vectors can transduce retinal pigment epithelium; one such early application was a phase I trial of AAV2-delivered pigment epithelium derived factor gene in advanced nAMD. Subsequently, gene therapy for AMD shifted to the investigation of soluble fms-like tyrosine kinase-1 (sFLT-1), an endogenously expressed VEGF inhibitor, binding and neutralizing VEGF-A. After some disappointing results, research has centered on novel vectors, including optimized AAV2, AAV8 and lentivirus, as well as genes encoding other anti-angiogenic proteins, including ranibizumab, aflibercept, angiostatin and endostatin. Also, gene therapy targeting the complement system is being investigated for geographic atrophy due to non-neovascular AMD. Expert opinion: The success of gene therapy for AMD will depend on the selection of the most appropriate therapeutic protein and its level of chronic expression. Future investigations will center on optimizing vector, promoter and delivery methods, and evaluating the risks of the chronic expression of anti-angiogenic or anti-complement proteins.
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Affiliation(s)
- Nicholas A Moore
- a Department of Ophthalmology , Indiana University School of Medicine , Indianapolis , IN , USA
| | - Peter Bracha
- a Department of Ophthalmology , Indiana University School of Medicine , Indianapolis , IN , USA
| | - Rehan M Hussain
- a Department of Ophthalmology , Indiana University School of Medicine , Indianapolis , IN , USA
| | - Nuria Morral
- c Department of Medical and Molecular Genetics , Indiana University School of Medicine , Indianapolis , IN , USA
| | - Thomas A Ciulla
- a Department of Ophthalmology , Indiana University School of Medicine , Indianapolis , IN , USA.,b Retina Service , Midwest Eye Institute , Indianapolis , IN , USA
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Abstract
Hepatitis C virus (HCV) is a leading cause of chronic hepatitis and infects approximately three to four million people per year, about 170 million infected people in total, making it one of the major global health problems. In a minority of cases HCV is cleared spontaneously, but in most of the infected individuals infection progresses to a chronic state associated with high risk to develop liver cirrhosis, hepatocellular cancer, or liver failure. The treatment of HCV infection has evolved over the years. Interferon (IFN)-α in combination with ribavirin has been used for decades as standard therapy. More recently, a new standard-of-care treatment has been approved based on a triple combination with either HCV protease inhibitor telaprevir or boceprevir. In addition, various options for all-oral, IFN-free regimens are currently being evaluated. Despite substantial improvement of sustained virological response rates, some intrinsic limitations of these new direct-acting antivirals, including serious side effects, the risk of resistance development and high cost, urge the development of alternative or additional therapeutic strategies. Gene therapy represents a feasible alternative treatment. Small RNA technology, including RNA interference (RNAi) techniques and antisense approaches, is one of the potentially promising ways to investigate viral and host cell factors that are involved in HCV infection and replication. With this, newly developed gene therapy regimens will be provided to treat HCV. In this chapter, a comprehensive overview guides you through the current developments and applications of RNAi and microRNA-based gene therapy strategies in HCV treatment.
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Ruiz R, Jideonwo V, Ahn M, Surendran S, Tagliabracci VS, Hou Y, Gamble A, Kerner J, Irimia-Dominguez JM, Puchowicz MA, DePaoli-Roach A, Hoppel C, Roach P, Morral N. Sterol regulatory element-binding protein-1 (SREBP-1) is required to regulate glycogen synthesis and gluconeogenic gene expression in mouse liver. J Biol Chem 2014; 289:5510-7. [PMID: 24398675 DOI: 10.1074/jbc.m113.541110] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Sterol regulatory element-binding protein-1 (SREBP-1) is a key transcription factor that regulates genes in the de novo lipogenesis and glycolysis pathways. The levels of SREBP-1 are significantly elevated in obese patients and in animal models of obesity and type 2 diabetes, and a vast number of studies have implicated this transcription factor as a contributor to hepatic lipid accumulation and insulin resistance. However, its role in regulating carbohydrate metabolism is poorly understood. Here we have addressed whether SREBP-1 is needed for regulating glucose homeostasis. Using RNAi and a new generation of adenoviral vector, we have silenced hepatic SREBP-1 in normal and obese mice. In normal animals, SREBP-1 deficiency increased Pck1 and reduced glycogen deposition during fed conditions, providing evidence that SREBP-1 is necessary to regulate carbohydrate metabolism during the fed state. Knocking SREBP-1 down in db/db mice resulted in a significant reduction in triglyceride accumulation, as anticipated. However, mice remained hyperglycemic, which was associated with up-regulation of gluconeogenesis gene expression as well as decreased glycolysis and glycogen synthesis gene expression. Furthermore, glycogen synthase activity and glycogen accumulation were significantly reduced. In conclusion, silencing both isoforms of SREBP-1 leads to significant changes in carbohydrate metabolism and does not improve insulin resistance despite reducing steatosis in an animal model of obesity and type 2 diabetes.
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Affiliation(s)
- Rafaela Ruiz
- From the Departments of Medical and Molecular Genetics and
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Ahn M, Gamble A, Witting SR, Magrisso J, Surendran S, Obici S, Morral N. Vector and helper genome rearrangements occur during production of helper-dependent adenoviral vectors. Hum Gene Ther Methods 2013; 24:1-10. [PMID: 23249343 PMCID: PMC4015077 DOI: 10.1089/hgtb.2012.198] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Helper-dependent adenoviral vectors (HD Ad) hold extreme promise for gene therapy of human diseases. All viral genes are deleted in HD Ad vectors, and therefore, the presence of a helper virus is required for their production. Current methods to minimize helper contamination in large-scale preparations rely on the use of the Cre/loxP system. The inclusion of loxP sites flanking the packaging signal results in its excision in the presence of Cre recombinase, preventing helper genome encapsidation. It is well established that the level of Cre recombinase activity is important in determining the degree of helper contamination. However, there is little information on other mechanisms that could also play an important role. We have generated several HD Ad vectors containing a rapalog-inducible system to regulate transgene expression, or LacZ under the control of the elongation factor 1 α promoter. Large-scale production of these vectors resulted in abundant helper contamination. Viral DNA analysis revealed the presence of rearrangements between vector and helper genomes. The rearrangements involved a helper DNA molecule with a fragment of the left arm of the HD Ad vector, including its ITR, packaging signal, and some stuffer sequence. Overall, our data suggest that helper DNA molecules that accumulate after Cre recombinase activity are prone to rearrangements, resulting in helper genomes that have incorporated a packaging signal from the vector. Helper particles with rearranged genomes have a growth advantage. This study identifies a novel mechanism leading to helper contamination during helper-dependent adenoviral vector production.
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Affiliation(s)
- Miwon Ahn
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Aisha Gamble
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Scott R. Witting
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Jack Magrisso
- Obesity Research Center, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH 45237
| | - Sneha Surendran
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Silvana Obici
- Obesity Research Center, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH 45237
| | - Núria Morral
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202.,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202
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Abstract
RNA interference (RNAi) is a cellular mechanism to inhibit the expression of gene products in a highly specific manner. In recent years, RNAi has become the cornerstone of gene function studies, shortening the otherwise long process of target identification and validation. In addition, small interfering RNA (siRNA) and short-hairpin RNA (shRNA) therapies are being developed for the treatment of a variety of human diseases. Despite its huge potential for gene silencing, a hurdle to safe and effective RNAi is the activation of innate immune responses. Induction of innate immunity is dose- and sequence-dependent, and is also influenced by target tissue and delivery vehicle. Research on the molecular mechanisms mediating this response is helping to improve the design of the RNAi molecules. Nevertheless, appropriate testing for the presence of this undesired effect is needed prior to making conclusions on the outcome of the silencing treatment.
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Affiliation(s)
- Núria Morral
- Department of Medical and Molecular Genetics, and Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Ahn M, Witting SR, Ruiz R, Saxena R, Morral N. Constitutive expression of short hairpin RNA in vivo triggers buildup of mature hairpin molecules. Hum Gene Ther 2011; 22:1483-97. [PMID: 21780944 DOI: 10.1089/hum.2010.234] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
RNA interference (RNAi) has become the cornerstone technology for studying gene function in mammalian cells. In addition, it is a promising therapeutic treatment for multiple human diseases. Virus-mediated constitutive expression of short hairpin RNA (shRNA) has the potential to provide a permanent source of silencing molecules to tissues, and it is being devised as a strategy for the treatment of liver conditions such as hepatitis B and hepatitis C virus infection. Unintended interaction between silencing molecules and cellular components, leading to toxic effects, has been described in vitro. Despite the enormous interest in using the RNAi technology for in vivo applications, little is known about the safety of constitutively expressing shRNA for multiple weeks. Here we report the effects of in vivo shRNA expression, using helper-dependent adenoviral vectors. We show that gene-specific knockdown is maintained for at least 6 weeks after injection of 1 × 10(11) viral particles. Nonetheless, accumulation of mature shRNA molecules was observed up to weeks 3 and 4, and then declined gradually, suggesting the buildup of mature shRNA molecules induced cell death with concomitant loss of viral DNA and shRNA expression. No evidence of well-characterized innate immunity activation (such as interferon production) or saturation of the exportin-5 pathway was observed. Overall, our data suggest constitutive expression of shRNA results in accumulation of mature shRNA molecules, inducing cellular toxicity at late time points, despite the presence of gene silencing.
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Affiliation(s)
- M Ahn
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Steele TWJ, Zhao X, Tarcha P, Kissel T. Factors influencing polycation/siRNA colloidal stability toward aerosol lung delivery. Eur J Pharm Biopharm 2011; 80:14-24. [PMID: 21924355 DOI: 10.1016/j.ejpb.2011.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 08/24/2011] [Accepted: 08/31/2011] [Indexed: 01/25/2023]
Abstract
Hexanediol diacrylate cross-linked oligoethylenimine (OEI-HD) is a non-viral polymeric vector designed to deliver siRNA. To achieve safe and effective in vivo siRNA delivery using this vector, the polyplex must have sufficient colloidal stability if administered intravenously or nebulized for delivery by the pulmonary route. In this study, polyplexes from OEI-HD and siRNA were formulated for aerosol-based lung delivery, regarding their colloidal stability, optimal particle size, and in vitro biological activity. Herein, we describe how these properties are dependent upon the polymer-to siRNA weight ratios, buffer composition they were complexed in, PEG-grafting, and the addition of commercial lung surfactants and/or non-ionic surfactants to the formulation. Lastly, the effects of nebulization of the formulation into aerosol droplets, on the polyplex particle size and transfection efficiency, were evaluated. Polyplex size was monitored for up to 2 h after polyplex formation to determine the extent of aggregation and final particle sizes when stability was achieved. Our results suggest that PEG-grafting and polyethylenimine-PEG mixing were effective in achieving colloidal stability in isotonic saline buffers. In addition, colloidal stability was achieved in isotonic glucose buffers using commercially available non-ionic surfactant Pluronic™ P68 or the lung-derived surfactant Alveofact™. The smallest particle size, 140 nm, was obtained with Pluronic™ F68. For transfection efficiency, both Alveofact™ and Pluronic™ F68 achieved equal or better transfection when added to the OEI-HD/siRNA polyplexes. For long term storage of OEI-HD/siRNA formulations, we propose a lyophilization method that created in situ polyplexes upon addition of water. Preparation of OEI-HD/siRNA polyplexes by this method allowed dry storage at room temperature for up to the 3 months. In conclusion, we have identified approaches to achieve formulation and colloidal stability of OEI-HD/siRNA complexes, a step toward successful application of polyplexes for in vivo siRNA delivery.
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Affiliation(s)
- Terry W J Steele
- School of Material Science & Engineering, Nanyang Technological University, Singapore, Singapore.
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Adenovirus and miRNAs. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:660-7. [PMID: 21621026 PMCID: PMC7102710 DOI: 10.1016/j.bbagrm.2011.05.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/05/2011] [Accepted: 05/09/2011] [Indexed: 01/15/2023]
Abstract
Adenovirus infection has a tremendous
impact on the cellular silencing machinery. Adenoviruses express high
amounts of non-coding virus associated (VA) RNAs able to saturate key
factors of the RNA interference (RNAi) processing pathway, such as
Exportin 5 and Dicer. Furthermore, a proportion of VA RNAs is cleaved by
Dicer into viral microRNAs (mivaRNAs) that can saturate Argonaute, an
essential protein for miRNA function. Thus, processing and function of
cellular miRNAs is blocked in adenoviral-infected cells. However, viral
miRNAs actively target the expression of cellular genes involved in
relevant functions such as cell proliferation, DNA repair or RNA
regulation. Interestingly, the cellular silencing machinery is active at
early times post-infection and can be used to control the adenovirus cell
cycle. This is relevant for therapeutic purposes against adenoviral
infections or when recombinant adenoviruses are used as vectors for gene
therapy. Manipulation of the viral genome allows the use of adenoviral
vectors to express therapeutic miRNAs or to be silenced by the RNAi
machinery leading to safer vectors with a specific tropism. This article
is part of a "Special Issue entitled:MicroRNAs in viral gene
regulation".
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Dharmapuri S, Peruzzi D, Marra E, Palombo F, Bett AJ, Bartz SR, Yong M, Ciliberto G, La Monica N, Buser CA, Toniatti C, Aurisicchio L. Intratumor RNA interference of cell cycle genes slows down tumor progression. Gene Ther 2011; 18:727-33. [PMID: 21390070 DOI: 10.1038/gt.2011.27] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Small interfering RNAs (siRNAs) are emerging as promising therapeutic tools. However, the widespread clinical application of such molecules as modulators of gene expression is still dependent on several aspects that limit their bioavailability. One of the most promising strategies to overcome the barriers faced by gene silencing molecules involves the use of lipid-based nanoparticles (LNPs) and viral vectors, such as adenoviruses (Ads). The primary obstacle for translating gene silencing technology from an effective research tool into a feasible therapeutic strategy remains its efficient delivery to the targeted cell type in vivo. In this study, we tested the capability of LNPs and Ad to transduce and treat locally tumors in vivo. Efficient knockdown of a surrogate reporter (luciferase) and therapeutic target genes such as the kinesin spindle protein (KIF11) and polo-like kinase 1 were observed. Most importantly, this activity led to a cell cycle block as a consequence and slowed down tumor progression in tumor-bearing animals. Our data indicate that it is possible to achieve tumor transduction with si/short hairpin RNAs and further improve the delivery strategy that likely in the future will lead to the ideal non-viral particle for targeted cancer gene silencing.
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Affiliation(s)
- S Dharmapuri
- Merck Research Laboratories, IRBM P Angeletti, Pomezia (Rome), Italy
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Park JS, Surendran S, Kamendulis LM, Morral N. Comparative nucleic acid transfection efficacy in primary hepatocytes for gene silencing and functional studies. BMC Res Notes 2011; 4:8. [PMID: 21244687 PMCID: PMC3033823 DOI: 10.1186/1756-0500-4-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 01/18/2011] [Indexed: 01/18/2023] Open
Abstract
Background Primary hepatocytes are the best resource for in vitro studies directed at understanding hepatic processes at the cellular and molecular levels, necessary for novel drug development to treat highly prevalent diseases such as non-alcoholic steatohepatitis, cardiovascular disease and type 2 diabetes. There is a need to identify simple methods to genetically manipulate primary hepatocytes and conduct functional studies with plasmids, small interfering RNA (siRNA) or microRNA (miRNA). New lipofection reagents are available that have the potential to yield higher levels of transfection with reduced toxicity. Findings We have tested several liposome-based transfection reagents used in molecular biology research. We show that transfection efficiency with one of the most recently developed formulations, Metafectene Pro, is high with plasmid DNA (>45% cells) as well as double stranded RNA (>90% with siRNA or microRNA). In addition, negligible cytotoxicity was present with all of these nucleic acids, even if cells were incubated with the DNA:lipid complex for 16 hours. To provide the proof of concept that these conditions can be used not only for overexpression of a gene of interest, but also in RNA interference applications, we targeted two liver expressed genes, Sterol Regulatory Element-Binding Protein-1 and Fatty Acid Binding Protein 5 using plasmid-mediated short hairpin RNA expression. In addition, similar transfection conditions were used to optimally deliver siRNA and microRNA. Conclusions We have identified a lipid-based reagent for primary hepatocyte transfection of nucleic acids currently used in molecular biology laboratories. The conditions described here can be used to expedite a large variety of research applications, from gene function studies to microRNA target identification.
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Affiliation(s)
- Jae-Seung Park
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, 975 West Walnut St, IB130, Indianapolis, Indiana 46202, USA.
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Abstract
Helper-dependent adenoviral vectors are devoid of all viral coding sequences, possess a large cloning capacity, and can efficiently transduce a wide variety of cell types from various species independent of the cell cycle to mediate long-term transgene expression without chronic toxicity. These non-integrating vectors hold tremendous potential for a variety of gene transfer and gene therapy applications. Here, we review the production technologies, applications, obstacles to clinical translation and their potential resolutions, and the future challenges and unanswered questions regarding this promising gene transfer technology.
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Affiliation(s)
- Amanda Rosewell
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030 USA
| | - Francesco Vetrini
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030 USA
| | - Philip Ng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030 USA
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Mowa MB, Crowther C, Arbuthnot P. Therapeutic potential of adenoviral vectors for delivery of expressed RNAi activators. Expert Opin Drug Deliv 2010; 7:1373-85. [PMID: 21073358 DOI: 10.1517/17425247.2010.533655] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
IMPORTANCE OF THE FIELD Harnessing RNA interference (RNAi) to silence pathology-causing genes has shown promise as a mode of therapy. The sustained gene inhibition that may be achieved with expressed sequences is potentially useful for treatment of chronic viral infections, but efficient and safe delivery of these sequences remains a challenge. It is generally recognized that there is no ideal vector for all therapeutic RNAi applications, but recombinant adenovirus vectors are well suited to hepatic delivery of expressed RNAi activators. AREAS COVERED IN THIS REVIEW Adenoviruses are hepatotropic after systemic administration, and this is useful for delivering expressed RNAi activators that silence pathology-causing genes in the liver. However, drawbacks of adenoviruses are toxicity and diminished efficacy, which result from induction of innate and adaptive immune responses. In this review, the advantages and hurdles facing therapeutic application of adenoviral vectors for liver delivery of RNAi effectors are covered. WHAT THE READER WILL GAIN Insights into adenovirus vectorology and the methods that have been used to make these vectors safer for advancing clinical application of RNAi-based therapy. TAKE HOME MESSAGE Adenoviruses are very powerful hepatotropic vectors. To make adenoviruses more effective for clinical use, polymer conjugation and deletion of viral vector sequences have been used successfully. However, further modifications to attenuate immunostimulation as well as improvements in large-scale production are necessary before the therapeutic potential of adenovirus-mediated delivery of RNAi activators is realized.
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Affiliation(s)
- Mohube Betty Mowa
- University of the Witwatersrand, School of Pathology, Antiviral Gene Therapy Research Unit, Health Sciences Faculty, Private Bag 3, WITS 2050, South Africa
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Vetrini F, Ng P. Gene therapy with helper-dependent adenoviral vectors: current advances and future perspectives. Viruses 2010; 2:1886-1917. [PMID: 21994713 PMCID: PMC3186006 DOI: 10.3390/v2091886] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 08/26/2010] [Accepted: 08/30/2010] [Indexed: 11/21/2022] Open
Abstract
Recombinant Adenoviral vectors represent one of the best gene transfer platforms due to their ability to efficiently transduce a wide range of quiescent and proliferating cell types from various tissues and species. The activation of an adaptive immune response against the transduced cells is one of the major drawbacks of first generation Adenovirus vectors and has been overcome by the latest generation of recombinant Adenovirus, the Helper-Dependent Adenoviral (HDAd) vectors. HDAds have innovative features including the complete absence of viral coding sequences and the ability to mediate high level transgene expression with negligible chronic toxicity. This review summarizes the many aspects of HDAd biology and structure with a major focus on in vivo gene therapy application and with an emphasis on the unsolved issues that these vectors still presents toward clinical application.
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Affiliation(s)
| | - Philip Ng
- Author to whom correspondence should be addressed; Tel.: +1 7137984158; E-Mail:
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Pan Q, Tilanus HW, Janssen HLA, van der Laan LJW. Prospects of RNAi and microRNA-based therapies for hepatitis C. Expert Opin Biol Ther 2009; 9:713-24. [DOI: 10.1517/14712590902989970] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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