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Progress and Prospects of Anti-HBV Gene Therapy Development. Int J Mol Sci 2015; 16:17589-610. [PMID: 26263978 PMCID: PMC4581210 DOI: 10.3390/ijms160817589] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 07/20/2015] [Accepted: 07/22/2015] [Indexed: 12/11/2022] Open
Abstract
Despite the availability of an effective vaccine against hepatitis B virus (HBV), chronic infection with the virus remains a major global health concern. Current drugs against HBV infection are limited by emergence of resistance and rarely achieve complete viral clearance. This has prompted vigorous research on developing better drugs against chronic HBV infection. Advances in understanding the life cycle of HBV and improvements in gene-disabling technologies have been impressive. This has led to development of better HBV infection models and discovery of new drug candidates. Ideally, a regimen against chronic HBV infection should completely eliminate all viral replicative intermediates, especially covalently closed circular DNA (cccDNA). For the past few decades, nucleic acid-based therapy has emerged as an attractive alternative that may result in complete clearance of HBV in infected patients. Several genetic anti-HBV strategies have been developed. The most studied approaches include the use of antisense oligonucleotides, ribozymes, RNA interference effectors and gene editing tools. This review will summarize recent developments and progress made in the use of gene therapy against HBV.
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Aquino-Jarquin G, Benítez-Hess ML, DiPaolo JA, Alvarez-Salas LM. A triplex ribozyme expression system based on a single hairpin ribozyme. Oligonucleotides 2009; 18:213-24. [PMID: 18707243 DOI: 10.1089/oli.2008.0130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Triplex ribozyme (RZ) configurations allow for the individual activity of trans-acting RZs in multiple expression cassettes (multiplex), thereby increasing target cleavage relative to conventionally expressed RZs. Although hairpin RZs have been advantageously compared to hammerhead RZs, their longer size and structural features complicated triplex design. We present a triplex expression system based on a single hairpin RZ with transcleavage capability and simple engineering. The system was tested in vitro using cis- and trans-cleavage kinetic assays against a known target RNA from HPV-16 E6/E7 mRNA. Single and multiplex triplex RZ constructs were more efficient in cleaving the target than tandem-cloned hairpin RZs, suggesting that the release of individual RZs enhanced trans-cleavage kinetics. Multiplex systems constructed with two different hairpin RZs resulted in better trans-cleavage compared to standard double-RZ constructs. In addition, the triplex RZ performed cis- and trans-cleavage in cervical cancer cells. The use of triplex configurations with multiplex RZs permit differential targeting of the same or different RNA, thus improving potential use against unstable targets. This prototype will provide the basis for the development of future RZ-based therapies and technologies.
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Affiliation(s)
- Guillermo Aquino-Jarquin
- Laboratorio de Terapia Génica, Departamento de Genética y Biología Molecular, CINVESTAV, México D.F., México
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Pardo M, Bartolomé J, Carreño V. Current therapy of chronic hepatitis B. Arch Med Res 2007; 38:661-77. [PMID: 17613358 DOI: 10.1016/j.arcmed.2006.12.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Accepted: 12/04/2006] [Indexed: 12/24/2022]
Affiliation(s)
- Margarita Pardo
- Fundación para el Estudio de las Hepatitis Virales, Madrid, Spain
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Márquez-Gutiérrez MA, Benítez-Hess ML, DiPaolo JA, Alvarez-Salas LM. Effect of combined antisense oligodeoxynucleotides directed against the human papillomavirus type 16 on cervical carcinoma cells. Arch Med Res 2007; 38:730-8. [PMID: 17845891 DOI: 10.1016/j.arcmed.2007.04.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 04/23/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND Cervical cancer is highly associated with human papillomavirus (HPV) E6 and E7 gene expression. We have previously reported two antisense oligodeoxynucleotides (AS-ODNs) directed against adjacent targets within the HPV-16 E6/E7 mRNA (419 and 434), each able to downregulate HPV-16 E6/E7 mRNA in vitro and in vivo and to specifically inhibit tumor cell growth in culture and animal models. METHODS Towards potential clinical application and improved in vivo performance, we analyzed the effect of the combined treatment of 419-434 AS-ODNs on the anchorage independent growth (AIG) of HPV-16-positive cervical carcinoma cell lines. RESULTS We found similar responses between combined 419-434 and individual AS-ODNs treatments in RNaseH assays, cell uptake, and in vivo degradation of HPV-16 E6/E7 transcripts. Moreover, the combined use of 419-434 AS-ODNs resulted in additive AIG inhibition of CaSki and SiHa cells, similar to that obtained with equivalent doses of the individual AS-ODNs. CONCLUSIONS By using a combined treatment, it may be possible to overcome the potential mutations frequently reported within HPV-16 genome, thus improving the potential application of 419 and 434 AS-ODNs as a therapeutic alternative for cervical cancer.
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Affiliation(s)
- Miguel A Márquez-Gutiérrez
- Laboratorio de Terapia Génica, Departamento de Genética y Biología Molecular, CINVESTAV, México DF, México
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Weinberg MS, Ely A, Passman M, Mufamadi SM, Arbuthnot P. Effective anti-hepatitis B virus hammerhead ribozymes derived from multimeric precursors. Oligonucleotides 2007; 17:104-12. [PMID: 17461767 DOI: 10.1089/oli.2006.0049] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Endonucleolytic hammerhead ribozymes have advantages of inhibiting gene expression by acting specifically, independently of cellular pathways, and within all cell compartments. However, there are concerns about inefficient silencing because of reduced intracellular cleavage of target RNA by ribozymes. To enable production of defined single-unit ribozymes and thereby increase effectiveness, we developed self-cleaving multimeric cassettes that generate several trans-acting ribozyme units from a single transcript. cis and trans ribozyme cleavage, as assessed in vitro against three different sites within the X sequence of hepatitis B virus (HBV), occurred efficiently and precisely according to predictions deduced from the ribozyme designs. Significant knockdown of markers of viral replication in transfected cultured liver-derived cells was achieved by multiribozyme Pol II expression cassettes. To assess silencing efficacy of RNA prepared in vitro, transcription and cis cleavage reactions were carried out to prepare defined single-unit ribozymes. Transfection of ribozyme RNA was capable of inhibiting HBV surface antigen secretion from liver-derived cells without associated elevation of interferon-alpha or interferon-beta secretion into the culture upernatants. The approach described here is potentially useful for several applications, such as generation of RNA interference (RNAi) effectors, which require rapid and inexpensive generation of defined RNA sequences.
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Affiliation(s)
- Marc S Weinberg
- Hepatitis B Virus Research Unit, Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School, WITS 2050, South Africa
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Fiola K, Perreault JP, Cousineau B. Gene targeting in the Gram-Positive bacterium Lactococcus lactis, using various delta ribozymes. Appl Environ Microbiol 2006; 72:869-79. [PMID: 16391129 PMCID: PMC1352214 DOI: 10.1128/aem.72.1.869-879.2006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The trans-acting antigenomic delta ribozyme, isolated from the human hepatitis delta virus, was shown to be highly stable and active in vitro, as well as in mammalian cell lines. However, the stability and gene-targeting competence of this small ribozyme have not been studied previously in bacterial cells. In this paper we describe the use of two variants of the trans-acting antigenomic delta ribozyme targeting the abundant EF-Tu mRNA in the industrially important gram-positive bacterium Lactococcus lactis. These two delta ribozyme variants were expressed at significant levels and were shown to be highly stable in vivo. The half-life of the EF-Tu mRNA was slightly but consistently reduced in the presence of the classical delta ribozymes (7 to 13%). In contrast, delta ribozymes harboring a specific on/off riboswitch (SOFA-delta ribozymes) targeting the same sites on the EF-Tu mRNA considerably reduced the half-life of this mRNA (22 to 47%). The rates of catalysis of the SOFA-delta ribozymes in L. lactis were similar to the rates determined in vitro, showing that this new generation of delta ribozymes was highly efficient in these bacterial cells. Clearly, SOFA-delta ribozymes appear to be an ideal means for development of gene inactivation systems in bacteria.
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Affiliation(s)
- Karine Fiola
- Department of Microbiology and Immunology, McGill University, Montréal, Québec H3A 2B4, Canada
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Wu J, Wu GY, Zern MA. The prospects of hepatic drug delivery and gene therapy. Expert Opin Investig Drugs 2005; 7:1795-817. [PMID: 15991930 DOI: 10.1517/13543784.7.11.1795] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Liver targeted therapy is designed to deliver a substance preferentially to the organ in order to increase the accumulation, improve the therapeutic effect and reduce toxicity to other organs. The aim of selective targeting is to deliver a substance to a specific cell type in the liver. A variety of vehicles have been designed and further modified for selective targeting of therapeutics to the liver. The targeting properties and strategies of commonly used agents, such as liposomes, microspheres and recombinant chylomicrons, are discussed. Viral and non-viral vectors, such as cationic liposomes, reconstituted chylomicron remnants, adenoviruses, adeno-associated viruses, retroviruses, and SV-40, are currently being evaluated for the delivery of DNA to the liver. New developments in improving the targeting efficiency of the available vectors while avoiding their disadvantages have made their use in clinical trials of various genetic disorders possible. For viral hepatitis, antisense and ribozyme techniques are being employed with selective targeting approaches. A commonly employed current strategy for targeting hepatocellular carcinoma cells is to make the tumour cells convert non-toxic 'prodrugs' to toxic metabolites in situ, achieving a high concentration of the toxic product in the local milieu, while avoiding systemic toxicity. Although gene therapy itself is in its infancy, some encouraging results have been developed in studies of familial hypercholesterolaemia, haemophilia, alpha1-antitrypsin deficiency and Crigler-Najjar syndrome. The potential strengths as well as the problems with these studies are discussed.
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Affiliation(s)
- J Wu
- Department of Medicine, Division of Gastroenterology & Hepatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5083, USA.
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Smicun Y, Kilpatrick MW, Florer J, Toudjarska I, Wu G, Wenstrup RJ, Tsipouras P. Enhanced intracellular availability and survival of hammerhead ribozymes increases target ablation in a cellular model of osteogenesis imperfecta. Gene Ther 2003; 10:2005-12. [PMID: 14566359 DOI: 10.1038/sj.gt.3302108] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Antisense hammerhead ribozymes have the capability to cleave complementary RNA in a sequence-dependent manner. In osteogenesis imperfecta, a genetic disorder of connective tissue, mutant collagen type I has been shown to participate in but not sustain formation of the triple helix. Selective ablation of mutant collagen gene transcript could potentially remove the mutant gene product and reverse the dominant-negative effect exerted by the abnormal protein. In earlier studies we showed that the hammerhead ribozyme Col1A1Rz547 selectively cleaved a mutant Col1A1 gene transcript in a murine calvarial osteoblast cell line. In order to test the possible therapeutic efficacy of this approach, a dramatic downregulation of the mutant transcript must be achieved, a function directly related to high steady-state level of intracellular ribozyme. We report significantly enhanced expression of Col1A1Rz547 by vaccinia T7 polymerase following infection with an attenuated T7-pol vaccinia virus as shown both by the intracellular level of the ribozyme and the cleavage of the mutant Col1A1 gene transcript. We also describe the engineering of a multimeric ribozyme construct comprising eight subunits, which can self-cleave to monomers. These studies suggest the potential use of multimeric ribozymes expressed by a vaccinia-based system in the therapy of a variety of disorders.
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Affiliation(s)
- Y Smicun
- Department of Pediatrics, University of Connecticut Health Center, Farmington, CT 06030, USA
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Bussière F, Ledû S, Girard M, Héroux M, Perreault JP, Matton DP. Development of an efficient cis-trans-cis ribozyme cassette to inactivate plant genes. PLANT BIOTECHNOLOGY JOURNAL 2003; 1:423-35. [PMID: 17134401 DOI: 10.1046/j.1467-7652.2003.00039.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Inactivation of a targeted gene is one of the main strategies used to understand their precise cellular role. In plants, apart from chemical or physical mutagenesis and random insertions of DNA elements followed by screening for a desired phenotype, the most common strategy to inhibit the expression of a given gene involves RNA silencing. This can be achieved either through antisense suppression, sense over-expression leading to co-suppression, or expression of double-stranded DNA constructs (dsRNA). The use of ribozymes to inhibit gene product accumulation has only been occasionally attempted, mainly because of the more complex genetic engineering procedure involved, although the specificity of ribozymes can be an important factor when targeting close members of a gene family. We report here the development of a new cis-acting ribozyme cassette for the production of RNAs with desired termini. Attention to many details has been brought in order to provide a powerful procedure for plant application. For example, ultrastable GNRA tetraloops were substituted for both loops II and III of cis-acting hammerhead sequences, thereby favouring folding into the catalytically active structure that results in the self-cleavage of all transcripts. We demonstrate the usefulness of this cassette by producing a ribozyme that cleaves in trans, originally embedded in the cis-acting self-cleaving cassette. The activity of the cis-trans-cis construct, was demonstrated both in vitro and in vivo, in transgenic plants with the specific cleavage of an mRNA encoding a 2-oxo-glutarate-dependant dioxygenase predominantly expressed in pistils tissues and in leaves, from the wild potato Solanum chacoense.
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Affiliation(s)
- Frédéric Bussière
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal, QC, H1X 2B2, Canada
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Feng Y, Kong YY, Wang Y, Qi GR. Inhibition of hepatitis B virus by hammerhead ribozyme targeted to the poly(A) signal sequence in cultured cells. Biol Chem 2001; 382:655-60. [PMID: 11405228 DOI: 10.1515/bc.2001.077] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The deviant poly(A) signal of hepatitis B virus (HBV) not only controls the formation of the 3' end of all the viral RNA, but is also crucial for HBV replication. Hence, a cis-releasing hammerhead ribozyme (RzA) targeted to the poly(A) signal region of HBV subtype adr was investigated for its antiviral effects. In vitro, RzA cleaved HBV RNA at its target site up to 70%, while the disabled ribozyme (dRzA), which had a one-base mutation in the catalytic site, did not cleave the target RNA at all. When the ribozymes were cotransfected into HepG2 cells with the HBV genome-containing plasmid p3.6II, the wild-type ribozyme RzA could effectively decrease HBV RNA levels and inhibit HBV replication, whereas its disabled form, dRzA, had much weaker effects, indicating that the active catalytic domain of the hammerhead ribozyme could markedly increase the extent of antisense-mediated inhibition. In addition, there was a gradient of effectiveness: the higher the amount of released ribozyme, the more the reduction in target HBV RNA in cells as well as progeny DNA reduction. These results suggest the possibility of the hammerhead ribozyme RzA to be used for the gene therapy of HBV infection.
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Affiliation(s)
- Y Feng
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences
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11
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Weinberg M, Passman M, Kew M, Arbuthnot P. Hammerhead ribozyme-mediated inhibition of hepatitis B virus X gene expression in cultured cells. J Hepatol 2000; 33:142-51. [PMID: 10905598 DOI: 10.1016/s0168-8278(00)80171-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND/AIMS Chronic infection with hepatitis B virus (HBV) is endemic to sub-Saharan Africa and parts of Asia. Common complications of HBV persistence include cirrhosis and hepatocellular carcinoma (HCC). Present treatment of chronic HBV infection is usually ineffective and novel therapeutic approaches are an important objective. The HBV X protein (HBx) is a transcriptional activator that is required for the establishment of HBV infection and is implicated in hepatocarcinogenesis. The aim of this study was to assess the ability of two endogenously expressed hammerhead ribozymes to inhibit expression of HBV genes in transfected cultured cells. METHODS Eukaryotic expression plasmids producing two ribozymes targeted to the HBx open reading frame, as well as their catalytically inactive homologues, were generated. Established cell lines and a primary culture of malignant hepatocytes were transfected to assess ribozyme effects on HBx expression and HBV replication. RESULTS The ribozyme-expressing vectors inhibit expression of functional HBx protein and decrease HBV mRNA encoding surface and HBx sequences in transfected cells. Moreover, decreased HBsAg and HBeAg secretion from cells transfected with the ribozymes and an HBV replication competent plasmid provide evidence for an antireplicative effect of the ribozymes. However, the data do not exclude a dominant antisense effect that inhibits HBV gene expression. CONCLUSIONS Inactivation of HBx, a sequence that is conserved in mammalian hepadnaviruses and found in all HBV transcripts, has potential for the treatment of chronic HBV infection.
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Affiliation(s)
- M Weinberg
- Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School, Parktown, South Africa
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Passman M, Weinberg M, Kew M, Arbuthnot P. In situ demonstration of inhibitory effects of hammerhead ribozymes that are targeted to the hepatitis Bx sequence in cultured cells. Biochem Biophys Res Commun 2000; 268:728-33. [PMID: 10679273 DOI: 10.1006/bbrc.2000.2209] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chronic hepatitis B virus (HBV) infection is endemic to several populous areas of the world and is frequently complicated by hepatocellular carcinoma. Ribozymes can be designed to cleave target RNA sequences specifically and show promise for the treatment of HBV infection. Demonstration of intracellular inhibition of HBV gene expression, essential to developing therapeutic ribozymes, has been the aim of this investigation. We generated two vectors encoding hammerhead ribozymes that target the HBx region of HBV. Plasmids containing intact HBV sequences or a modification in which the preS2/S region was replaced by DNA encoding enhanced green fluorescent protein (EGFP) were used to test ribozyme action in transfected cells. Both ribozymes inhibited surface antigen secretion and EGFP expression similarly. The measurement of EGFP expression is convenient to assess ribozyme action in situ and effective targeting of HBV sequences that are common to all HBV transcripts is potentially useful to develop strategies to counter HBV infection.
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Affiliation(s)
- M Passman
- Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School, 7 York Road, Parktown, 2193, South Africa
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Abstract
The advantages and disadvantages of viral and non-viral vectors for gene delivery are reviewed. Advances in systems for introduction of new gene expression are described, including self-deleting retroviral transfer vectors, chimeric viruses and chimeric oligonucleotides. Systems for inhibition of gene expression are also discussed including antisense oligonucleotides, ribozymes and dominant-negative genes. Examples of the use of these systems in animal models and clinical trials for gastrointestinal disorders are discussed.
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Affiliation(s)
- Edwin C Ouyang
- Department of Medicine, Division of Gastroenterology-Hepatology, University of Connecticut School of Medicine, Farmington, Connecticut, USA
| | - George Y Wu
- Department of Medicine, Division of Gastroenterology-Hepatology, University of Connecticut School of Medicine, Farmington, Connecticut, USA
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Welch PJ, Barber JR, Wong-Staal F. Expression of ribozymes in gene transfer systems to modulate target RNA levels. Curr Opin Biotechnol 1998; 9:486-96. [PMID: 9821277 DOI: 10.1016/s0958-1669(98)80034-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The possibility of designing ribozymes to cleave any specific target RNA has rendered them valuable tools in both basic research and therapeutic applications. In the therapeutics area, they have been exploited to target viral RNAs in infectious diseases, dominant oncogenes in cancers and specific somatic mutations in genetic disorders. Most notably, several ribozyme gene therapy protocols for HIV patients are already in Phase 1 trials. More recently, ribozymes have been used for transgenic animal research, gene target validation and pathway elucidation.
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Affiliation(s)
- P J Welch
- Immusol Inc., San Diego, CA 92121, USA.
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Asahina Y, Ito Y, Wu CH, Wu GY. DNA ribonucleases that are active against intracellular hepatitis B viral RNA targets. Hepatology 1998; 28:547-54. [PMID: 9696023 DOI: 10.1002/hep.510280236] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
DNA ribonucleases directed against direct repeat 1 (DR1) and polyadenylation signal regions of hepatitis B virus (HBV) messages were prepared with phosphorothioate modifications and varying arm lengths. DNA ribonucleases modified throughout the entire molecule and in the target binding arms were completely protected from degradation after incubation with serum. DNA ribonuclease modified only at the 5' and 3' termini remained 92.9% intact after incubation. Molecules with no modification were degraded to 67.6% under the same conditions. However, modification of the entire molecule and in the recognition arms resulted in 99.8% and 98.4% inactivation of cleavage activity, respectively. Modification of only the termini resulted in retention of 20% to 40% of original activity. Lengthening each terminally modified arm from 9 to 11 nucleotides increased cleavage efficiency almost 10-fold. In Huh 7 cells, DR1-directed DNA ribonucleases with terminal modifications significantly suppressed HBV-luciferase fusion gene expression up to 48% of control. In contrast, DNA ribonucleases had no effect on a control construct lacking any HBV target sequences. Moreover, inactivated mutant and HCV-directed DNA ribonucleases had no significant effects on the HBV target. We conclude that resistance of DNA ribonucleases to degradation can be enhanced through phosphorothioate modification. Cleavage activity can be retained by limiting modification to the termini and lengthening the recognition arms. Such DNA ribonucleases can be made to specifically cleave target HBV RNA and substantially inhibit intracellular viral gene expression.
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Affiliation(s)
- Y Asahina
- Department of Medicine, University of Connecticut Health Center, Farmington 06030, USA
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Diegelman AM, Kool ET. Generation of circular RNAs and trans-cleaving catalytic RNAs by rolling transcription of circular DNA oligonucleotides encoding hairpin ribozymes. Nucleic Acids Res 1998; 26:3235-41. [PMID: 9628924 PMCID: PMC147673 DOI: 10.1093/nar/26.13.3235] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A simple new strategy for the in vitro synthesis of circular RNAs and hairpin ribozymes is described. Circular single-strand DNA oligonucleotides 67-79 nt in length are constructed to encode both hairpin ribozyme sequences and ribozyme-cleavable sequences. In vitro transcription of these small circles by Escherichia coli RNA polymerase produces long repeating RNAs by a rolling circle mechanism. These repetitive RNAsundergo self-processing, eventually yielding unit length circular and linear RNAs as the chief products. The transcription is efficient despite the absence of promoter sequences, with RNA being produced in up to 400 times the amount of DNA circle used. It is shown that the linear monomeric hairpin ribozymes are active in cleaving RNA targets in trans , including one from HIV-1. Several new findings are established: (i) that rolling circle transcription can be extended to the synthesis of catalytic RNAs outside the hammerhead ribozyme motif; (ii) that rolling circle transcription is potentially a very simple and useful strategy for the generation of circular RNAs in preparative amounts; and (iii) that self-processed hairpin ribozymes can be catalytically active in trans despite the presence of self-binding domains.
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Affiliation(s)
- A M Diegelman
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
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