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Khalifah BA, Alghamdi SA, Alhasan AH. Unleashing the potential of catalytic RNAs to combat mis-spliced transcripts. Front Bioeng Biotechnol 2023; 11:1244377. [PMID: 38047291 PMCID: PMC10690607 DOI: 10.3389/fbioe.2023.1244377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/23/2023] [Indexed: 12/05/2023] Open
Abstract
Human transcriptome can undergo RNA mis-splicing due to spliceopathies contributing to the increasing number of genetic diseases including muscular dystrophy (MD), Alzheimer disease (AD), Huntington disease (HD), myelodysplastic syndromes (MDS). Intron retention (IR) is a major inducer of spliceopathies where two or more introns remain in the final mature mRNA and account for many intronic expansion diseases. Potential removal of such introns for therapeutic purposes can be feasible when utilizing bioinformatics, catalytic RNAs, and nano-drug delivery systems. Overcoming delivery challenges of catalytic RNAs was discussed in this review as a future perspective highlighting the significance of utilizing synthetic biology in addition to high throughput deep sequencing and computational approaches for the treatment of mis-spliced transcripts.
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Affiliation(s)
- Bashayer A. Khalifah
- Institute for Bioengineering, Health Sector, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
- Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - Ali H. Alhasan
- Institute for Bioengineering, Health Sector, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
- College of Science and General Studies, Alfaisal University, Riyadh, Saudi Arabia
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2
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Zhao Y, Shu R, Liu J. The development and improvement of ribonucleic acid therapy strategies. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 26:997-1013. [PMID: 34540356 PMCID: PMC8437697 DOI: 10.1016/j.omtn.2021.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The biological understanding of RNA has evolved since the discovery of catalytic RNAs in the early 1980s and the establishment of RNA interference (RNAi) in the 1990s. RNA is no longer seen as the simple mid-product between transcription and translation but as potential molecules to be developed as RNA therapeutic drugs. RNA-based therapeutic drugs have gained recognition because of their ability to regulate gene expression and perform cellular functions. Various nucleobase, backbone, and sugar-modified oligonucleotides have been synthesized, as natural oligonucleotides have some limitations such as poor low nuclease resistance, binding affinity, poor cellular uptake, and toxicity, which affect their use as RNA therapeutic drugs. In this review, we briefly discuss different RNA therapeutic drugs and their internal connections, including antisense oligonucleotides, small interfering RNAs (siRNAs) and microRNAs (miRNAs), aptamers, small activating RNAs (saRNAs), and RNA vaccines. We also discuss the important roles of RNA vaccines and their use in the fight against COVID-19. In addition, various chemical modifications and delivery systems used to improve the performance of RNA therapeutic drugs and overcome their limitations are discussed.
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Affiliation(s)
- Yuxi Zhao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Rui Shu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
- Corresponding author: Rui Shu, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
| | - Jiang Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
- Corresponding author: Jiang Liu, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
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Abstract
BACKGROUND RNA trans-splicing joins exons from different pre-mRNA transcripts to generate a chimeric product. Trans-splicing can also occur at the protein level, with split inteins mediating the ligation of separate gene products to generate a mature protein. SOURCES OF DATA Comprehensive literature search of published research papers and reviews using Pubmed. AREAS OF AGREEMENT Trans-splicing techniques have been used to target a wide range of diseases in both in vitro and in vivo models, resulting in RNA, protein and functional correction. AREAS OF CONTROVERSY Off-target effects can lead to therapeutically undesirable consequences. In vivo efficacy is typically low, and delivery issues remain a challenge. GROWING POINTS Trans-splicing provides a promising avenue for developing novel therapeutic approaches. However, much more research needs to be done before developing towards preclinical studies. AREAS TIMELY FOR DEVELOPING RESEARCH Increasing trans-splicing efficacy and specificity by rational design, screening and competitive inhibition of endogenous cis-splicing.
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Affiliation(s)
- Elizabeth M Hong
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Carin K Ingemarsdotter
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Andrew M L Lever
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
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Lee CH, Han SR, Lee SW. Group I Intron-Based Therapeutics Through Trans-Splicing Reaction. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 159:79-100. [PMID: 30340790 DOI: 10.1016/bs.pmbts.2018.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In 1982, the Cech group discovered that an intron structure in an rRNA precursor of Tetrahymena thermophila is sufficient to complete splicing without assistance from proteins. This was the first moment that scientists recognized RNAs can have catalytic activities derived from their own unique three-dimensional structures and thus play more various roles in biological processes than thought before. Several additional catalytic RNAs, called ribozymes, were subsequently identified in nature followed by intense studies to reveal their mechanisms of action and to engineer them for use in fields such as molecular cell biology, therapeutics, imaging, etc. Naturally occurring RNA-targeting ribozymes can be broadly classified into two categories by their abilities: Self-cleavage and self-splicing. Since ribozymes use base-pairing to recognize cleavage sites, identification of the catalytic center of naturally occurring ribozymes enables to engineer from "self" to "trans" acting ones which has accelerated to design and use ribozyme as valuable tools in gene therapy fields. Especially, group I intron-based trans-splicing ribozyme has unique property to use as a gene therapeutic agent. It can destroy and simultaneously repair (and/or reprogram) target RNAs to yield the desired therapeutic RNAs, maintaining endogenous spatial and temporal gene regulation of target RNAs. There have been progressive improvements in trans-splicing ribozymes and successful applications of these elements in gene therapy and molecular imaging approaches for various pathogenic conditions. In this chapter, current status of trans-splicing ribozyme therapeutics, focusing on Tetrahymena group I intron-based ribozymes, and their future prospects will be discussed.
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Affiliation(s)
- Chang Ho Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
| | | | - Seong-Wook Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea; Rznomics Inc., Gwangju, Republic of Korea.
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Lee CH, Han SR, Lee SW. Therapeutic applications of group I intron-based trans-splicing ribozymes. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1466. [PMID: 29383855 DOI: 10.1002/wrna.1466] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 12/10/2017] [Accepted: 12/14/2017] [Indexed: 12/21/2022]
Abstract
Since the breakthrough discovery of catalytic RNAs (ribozymes) in the early 1980s, valuable ribozyme-based gene therapies have been developed for incurable diseases ranging from genetic disorders to viral infections and cancers. Ribozymes can be engineered and used to downregulate or repair pathogenic genes via RNA cleavage mediated by trans-cleaving ribozymes or repair and reprograming mediated by trans-splicing ribozymes, respectively. Uniquely, trans-splicing ribozymes can edit target RNAs via simultaneous destruction and repair (and/or reprograming) to yield the desired therapeutic RNAs, thus selectively inducing therapeutic gene activity in cells expressing the target RNAs. In contrast to traditional gene therapy approaches, such as simple addition of therapeutic transgenes or inhibition of disease-causing genes, the selective repair and/or reprograming abilities of trans-splicing ribozymes in target RNA-expressing cells facilitates the maintenance of endogenous spatial and temporal gene regulation and reduction of disease-associated transcript expression. In molecular imaging technologies, trans-splicing ribozymes can be used to reprogram specific RNAs in living cells and organisms by the 3'-tagging of reporter RNAs. The past two decades have seen progressive improvements in trans-splicing ribozymes and the successful application of these elements in gene therapy and molecular imaging approaches for various pathogenic conditions, such as genetic, infectious, and malignant disease. This review provides an overview of the current status of trans-splicing ribozyme therapeutics, focusing on Tetrahymena group I intron-based ribozymes, and their future prospects. This article is categorized under: RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Chang Ho Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
| | - Seung Ryul Han
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
| | - Seong-Wook Lee
- Department of Integrated Life Sciences, Dankook University, Yongin, Republic of Korea
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Kim SJ, Kim JH, Yang B, Jeong JS, Lee SW. Specific and Efficient Regression of Cancers Harboring KRAS Mutation by Targeted RNA Replacement. Mol Ther 2017; 25:356-367. [PMID: 28153088 DOI: 10.1016/j.ymthe.2016.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 11/01/2016] [Accepted: 11/11/2016] [Indexed: 12/30/2022] Open
Abstract
Mutations in the KRAS gene, which persistently activate RAS function, are most frequently found in many types of human cancers. Here, we proposed and verified a new approach against cancers harboring the KRAS mutation with high cancer selectivity and efficient anti-cancer effects based on targeted RNA replacement. To this end, trans-splicing ribozymes from Tetrahymena group I intron were developed, which can specifically target and reprogram the mutant KRAS G12V transcript to induce therapeutic gene activity in cells. Adenoviral vectors containing the specific ribozymes with downstream suicide gene were constructed and then infection with the adenoviruses specifically downregulated KRAS G12V expression and killed KRAS G12V-harboring cancer cells additively upon pro-drug treatment, but it did not affect the growth of wild-type KRAS-expressing cells. Minimal liver toxicity was noted when the adenoviruses were administered systemically in vivo. Importantly, intratumoral injection of the adenoviruses with pro-drug treatment specifically and significantly impeded the growth of xenografted tumors harboring KRAS G12V through a trans-splicing reaction with the target RNA. In contrast, xenografted tumors harboring wild-type KRAS were not affected by the adenoviruses. Therefore, RNA replacement with a mutant KRAS-targeting trans-splicing ribozyme is a potentially useful therapeutic strategy to combat tumors harboring KRAS mutation.
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Affiliation(s)
- Sung Jin Kim
- Department of Integrated Life Sciences, Research Institute of Advanced Omics, Dankook University, Yongin 16890, Republic of Korea
| | - Ju Hyun Kim
- Department of Integrated Life Sciences, Research Institute of Advanced Omics, Dankook University, Yongin 16890, Republic of Korea
| | - Bitna Yang
- Department of Integrated Life Sciences, Research Institute of Advanced Omics, Dankook University, Yongin 16890, Republic of Korea
| | - Jin-Sook Jeong
- Department of Pathology and Immune-network Pioneer Research Center, Dong-A University College of Medicine, Busan 49202, Republic of Korea
| | - Seong-Wook Lee
- Department of Integrated Life Sciences, Research Institute of Advanced Omics, Dankook University, Yongin 16890, Republic of Korea.
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Design and Experimental Evolution of trans-Splicing Group I Intron Ribozymes. Molecules 2017; 22:molecules22010075. [PMID: 28045452 PMCID: PMC6155759 DOI: 10.3390/molecules22010075] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 12/27/2016] [Accepted: 12/29/2016] [Indexed: 12/31/2022] Open
Abstract
Group I intron ribozymes occur naturally as cis-splicing ribozymes, in the form of introns that do not require the spliceosome for their removal. Instead, they catalyze two consecutive trans-phosphorylation reactions to remove themselves from a primary transcript, and join the two flanking exons. Designed, trans-splicing variants of these ribozymes replace the 3′-portion of a substrate with the ribozyme’s 3′-exon, replace the 5′-portion with the ribozyme’s 5′-exon, or insert/remove an internal sequence of the substrate. Two of these designs have been evolved experimentally in cells, leading to variants of group I intron ribozymes that splice more efficiently, recruit a cellular protein to modify the substrate’s gene expression, or elucidate evolutionary pathways of ribozymes in cells. Some of the artificial, trans-splicing ribozymes are promising as tools in therapy, and as model systems for RNA evolution in cells. This review provides an overview of the different types of trans-splicing group I intron ribozymes that have been generated, and the experimental evolution systems that have been used to improve them.
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Carter JR, Taylor S, Fraser TS, Kucharski CA, Dawson JL, Fraser MJ. Suppression of the Arboviruses Dengue and Chikungunya Using a Dual-Acting Group-I Intron Coupled with Conditional Expression of the Bax C-Terminal Domain. PLoS One 2015; 10:e0139899. [PMID: 26580561 PMCID: PMC4651551 DOI: 10.1371/journal.pone.0139899] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 09/18/2015] [Indexed: 11/19/2022] Open
Abstract
In portions of South Asia, vectors and patients co-infected with dengue (DENV) and chikungunya (CHIKV) are on the rise, with the potential for this occurrence in other regions of the world, for example the United States. Therefore, we engineered an antiviral approach that suppresses the replication of both arboviruses in mosquito cells using a single antiviral group I intron. We devised unique configurations of internal, external, and guide sequences that permit homologous recognition and splicing with conserved target sequences in the genomes of both viruses using a single trans-splicing Group I intron, and examined their effectiveness to suppress infections of DENV and CHIKV in mosquito cells when coupled with a proapoptotic 3' exon, ΔN Bax. RT-PCR demonstrated the utility of these introns in trans-splicing the ΔN Bax sequence downstream of either the DENV or CHIKV target site in transformed Aedes albopictus C6/36 cells, independent of the order in which the virus specific targeting sequences were inserted into the construct. This trans-splicing reaction forms DENV or CHIKV ΔN Bax RNA fusions that led to apoptotic cell death as evidenced by annexin V staining, caspase, and DNA fragmentation assays. TCID50-IFA analyses demonstrate effective suppression of DENV and CHIKV infections by our anti-arbovirus group I intron approach. This represents the first report of a dual-acting Group I intron, and demonstrates that we can target DENV and CHIKV RNAs in a sequence specific manner with a single, uniquely configured CHIKV/DENV dual targeting group I intron, leading to replication suppression of both arboviruses, and thus providing a promising single antiviral for the transgenic suppression of multiple arboviruses.
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Affiliation(s)
- James R. Carter
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Samantha Taylor
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Tresa S. Fraser
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Cheryl A. Kucharski
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - James L. Dawson
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Malcolm J. Fraser
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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Lee CH, Han SR, Lee SW. Therapeutic Applications of Aptamer-Based Riboswitches. Nucleic Acid Ther 2015; 26:44-51. [PMID: 26539634 DOI: 10.1089/nat.2015.0570] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Aptamers bind to their targets with high affinity and specificity through structure-based complementarity, instead of sequence complementarity that is used by most of the oligonucleotide-based therapeutics. This property has been exploited in using aptamers as multifunctional therapeutic units, by attaching them to therapeutic drugs, nanoparticles, or imaging agents, or as direct molecular decoys for inducing loss-of-function or gain-of-function of targets. One of the most interesting fields of aptamer application is their development as molecular sensors to regulate artificial riboswitches. Naturally, the riboswitches sense small-molecule metabolites and respond by regulating the expression of the corresponding metabolic genes. Riboswitches are cis-acting RNA structures that consist of the sensing (aptamer) and the regulating (expression platform) domains. In principle, diverse riboswitches can be engineered and applied to control different steps of gene expression in bacterial species as well as eukaryotes, by simply replacing aptamers against various endogenous and/or exogenous targets. Although these engineered aptamer-based riboswitches are recently gaining attention, it is clear that aptamer-based riboswitches have a potential for next-generation therapeutics against various diseases because of their controllability, specificity, and modularity in regulating gene expression through various cellular processes, including transcription, splicing, stability, RNA interference, and translation. In this review, we provide a summary of the recently developed and engineered aptamer-based riboswitches focusing on their therapeutic availability and further discuss their clinical potential.
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Affiliation(s)
- Chang Ho Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, and Research Institute of Advanced Omics, Dankook University , Yongin, Republic of Korea
| | - Seung Ryul Han
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, and Research Institute of Advanced Omics, Dankook University , Yongin, Republic of Korea
| | - Seong-Wook Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, and Research Institute of Advanced Omics, Dankook University , Yongin, Republic of Korea
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10
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Nawtaisong P, Fraser ME, Carter JR, Fraser MJ. Trans-splicing group I intron targeting hepatitis C virus IRES mediates cell death upon viral infection in Huh7.5 cells. Virology 2015; 481:223-34. [PMID: 25840398 DOI: 10.1016/j.virol.2015.02.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 11/25/2014] [Accepted: 02/09/2015] [Indexed: 01/17/2023]
Abstract
The HCV-IRES sequence is vital for both protein translation and genome replication and serves as a potential target for anti-HCV therapy. We constructed a series of anti-HCV group I introns (αHCV-GrpIs) to attack conserved target sites within the HCV IRES. These αHCV-GrpIs were designed to mediate a trans-splicing reaction that replaces the viral RNA genome downstream of the 5' splice site with a 3' exon that encodes an apoptosis-inducing gene. Pro-active forms of the apoptosis inducing genes BID, Caspase 3, Caspase 8, or tBax were modified by incorporation of the HCV NS5A/5B cleavage sequence in place of their respective endogenous cleavage sites to ensure that only HCV infected cells would undergo apoptosis following splicing and expression. Huh7.5 cells transfected with each intron were challenged at MOI 0.1 with HCV-Jc1FLAG2 which expresses a Gaussia Luciferase (GLuc) marker. Virus-containing supernatants were then assayed for GLuc expression as a measure of viral replication inhibition. Cellular extracts were analyzed for the presence of correct splice products by RT-PCR and DNA sequencing. We also measured levels of Caspase 3 activity as a means of quantifying apoptotic cell death. Each of these αHCV-GrpI introns was able to correctly splice their 3' apoptotic exons onto the virus RNA genome at the targeted Uracil, and resulted in greater than 80% suppression of the GLuc marker. A more pronounced suppression effect was observed with TCID₅₀ virus titrations, which demonstrated that these αHCV-GrpIs were able to suppress viral replication by more than 2 logs, or greater than 99%. Robust activation of the apoptotic factor within the challenged cells was evidenced by a significant increase of Caspase 3 activity upon viral infection compared to non-challenged cells. This novel genetic intervention tool may prove beneficial in certain HCV subjects.
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Affiliation(s)
- Pruksa Nawtaisong
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Mark E Fraser
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, United States
| | - James R Carter
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Malcolm J Fraser
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, United States.
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Franz AWE, Balaraman V, Fraser MJ. Disruption of dengue virus transmission by mosquitoes. CURRENT OPINION IN INSECT SCIENCE 2015; 8:88-96. [PMID: 26120563 PMCID: PMC4480767 DOI: 10.1016/j.cois.2014.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Current control efforts for mosquito-borne arboviruses focus on mosquito control involving insecticide applications, which are becoming increasingly ineffective and unsustainable in urban areas. Mosquito population replacement is an alternative arbovirus control concept aiming at replacing virus-competent vector populations with laboratory-engineered incompetent vectors. A prerequisite for this strategy is the design of robust anti-pathogen effectors that can ultimately be genetically driven through a wild-type population. Several anti-pathogen effector concepts have been developed that target the RNA genomes of arboviruses such as dengue virus in a highly sequence-specific manner. Design principles are based on long inverted-repeat RNA triggered RNA interference, catalytic hammerhead ribozymes, and trans-splicing Group I Introns that are able to induce apoptosis in virus-infected cells following splicing with target viral RNA.
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Affiliation(s)
- Alexander W E Franz
- Department of Veterinary Pathobiology, 303 Connaway Hall, College of Veterinary Medicine, University of Missouri, Columbia MO, 65211, United States of America
| | - Velmurugan Balaraman
- Department of Veterinary Pathobiology, 303 Connaway Hall, College of Veterinary Medicine, University of Missouri, Columbia MO, 65211, United States of America
| | - Malcolm J Fraser
- Department of Biological Sciences, 218 Galvin Life Science Bldg., University of Notre Dame, South Bend IN, 46617, United States of America
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Kim J, Jeong S, Kertsburg A, Soukup GA, Lee SW. Conditional and target-specific transgene induction through RNA replacement using an allosteric trans-splicing ribozyme. ACS Chem Biol 2014; 9:2491-5. [PMID: 25265474 DOI: 10.1021/cb500567v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gene therapeutic approaches are needed that can simultaneously induce the well-controlled expression of therapeutic genes and suppress the expression of disease-causing genes for maximization of their efficacy. To address this challenge, we designed an allosteric ribozyme that comprises a Tetrahymena group I-based trans-splicing ribozyme as an active domain for RNA replacement, a small molecule-specific RNA aptamer as a sensor domain, and a communication module as an active transfer domain. The effectiveness of this approach was assessed by constructing various ribozymes in combination with a theophylline-binding aptamer to identify an allosteric ribozyme, which is controlled by theophylline both in vitro and in cells. Moreover, we constructed adenoviral vectors encoding the ribozymes and validated allosteric regulation of trans-gene expression via theophylline-dependent RNA replacement in target RNA-expressing cells. Results demonstrate that an allosteric trans-splicing ribozyme is an applicable RNA-based framework for engineering external ligand-controlled gene expression regulatory systems that exhibit adjustable regulation, design modularity, and target specificity.
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Affiliation(s)
- Juhyun Kim
- Department
of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
| | - Seonyeong Jeong
- Department
of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
| | - Alexis Kertsburg
- Department
of Biomedical Sciences, School of Medicine, Creighton University, Omaha, Nebraska 68178, United States
| | - Garrett A. Soukup
- Department
of Biomedical Sciences, School of Medicine, Creighton University, Omaha, Nebraska 68178, United States
| | - Seong-Wook Lee
- Department
of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
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Won YS, Jeong JS, Kim SJ, Ju MH, Lee SW. Targeted anticancer effect through microRNA-181a regulated tumor-specific hTERT replacement. Cancer Lett 2014; 356:918-28. [PMID: 25444904 DOI: 10.1016/j.canlet.2014.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 11/01/2014] [Accepted: 11/04/2014] [Indexed: 01/11/2023]
Abstract
We previously generated a group I intron-based ribozyme that can reprogram human telomerase reverse transcriptase (hTERT) RNA to stimulate transgene activity in cancer cells expressing the target RNA via an accurate and specific trans-splicing reaction. One of the major concerns of the hTERT RNA targeting anti-cancer approach is the potential side effects to hTERT(+) hematopoietic stem cell-derived blood cells. Thus, here we modified the ribozyme by inserting target sites against microRNA-181a, which is a blood cell-specific microRNA, downstream of its 3' exon. The specificity of transgene induction and anticancer activity in hTERT(+) cancer cells improved significantly with the modified ribozyme, resulting in selective targeting of hTERT(+) cancer cells, but not hematopoietic cells even if they are hTERT-positive. Importantly, the trans-splicing reaction of the microRNA-regulated ribozyme worked equally well in a nude mouse model of hepatocarcinoma-derived intrasplenic carcinomatosis, inducing highly specific expression of a therapeutic transgene and efficiently regressing hTERT-positive liver tumors with minimal liver toxicity when systemically delivered with an adenoviral vector encoding the ribozyme. These results suggest that a combined approach of microRNA regulation with targeted RNA replacement is more useful for effective anti-cancer treatment.
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Affiliation(s)
- You-Sub Won
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, and Research Institute of Advanced Omics, Dankook University, Yongin, Republic of Korea
| | - Jin-Sook Jeong
- Department of Pathology and Medical Research Center for Cancer Molecular Therapy, Dong-A University College of Medicine, Busan, Republic of Korea
| | - Sung Jin Kim
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, and Research Institute of Advanced Omics, Dankook University, Yongin, Republic of Korea
| | - Mi Ha Ju
- Department of Pathology and Medical Research Center for Cancer Molecular Therapy, Dong-A University College of Medicine, Busan, Republic of Korea
| | - Seong-Wook Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, and Research Institute of Advanced Omics, Dankook University, Yongin, Republic of Korea.
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14
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Kim SJ, Lee SW. Selective expression of transgene using hypoxia-inducible trans-splicing group I intron ribozyme. J Biotechnol 2014; 192 Pt A:22-7. [PMID: 25312327 DOI: 10.1016/j.jbiotec.2014.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/12/2014] [Accepted: 10/01/2014] [Indexed: 11/16/2022]
Abstract
Low oxygen conditions, termed hypoxia, can affect cell survivals. Cells may adapt to hypoxic conditions through hypoxia response elements (HRE) such as erythropoietin enhancer or phosphoglycerate kinase element. Hypoxic conditions usually appear in solid tumors, and can cause resistance to radiotherapy or chemotherapy. In this study, a genetic approach based upon Tetrahymena group I ribozyme was developed, which can address the challenges induced by a hypoxic microenvironment. To this end, human telomerase reverse transcriptase (hTERT) targeting trans-splicing ribozymes whose expression and activity were induced by HRE under hypoxia were constructed. Luciferase reporter assay showed induction of the transgene to increase due to the hypoxia-inducible ribozymes through a specific trans-splicing reaction in hTERT-expressing cells under hypoxic conditions. Increase in the transgene expression was mainly due to the increased trans-splicing reaction through a concurrent increase of the ribozyme expression level. Moreover, hypoxia-inducible ribozyme with herpes simplex virus thymidine kinase as the 3'exon effectively induced cell death when treated with ganciclovir under both hypoxic and normoxic conditions. These results indicated that the trans-splicing ribozyme could be a target-specific and efficacious anti-cancer tool to overcome resistance to radio- and chemotherapy under hypoxic conditions.
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Affiliation(s)
- Sung Jin Kim
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, 126, Jukjeon-dong, Suji-gu, Yongin 448-701, Republic of Korea
| | - Seong-Wook Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, 126, Jukjeon-dong, Suji-gu, Yongin 448-701, Republic of Korea.
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15
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Amini ZN, Olson KE, Müller UF. Spliceozymes: ribozymes that remove introns from pre-mRNAs in trans. PLoS One 2014; 9:e101932. [PMID: 25014025 PMCID: PMC4094466 DOI: 10.1371/journal.pone.0101932] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Accepted: 06/13/2014] [Indexed: 11/25/2022] Open
Abstract
Group I introns are pre-mRNA introns that do not require the spliceosome for their removal. Instead, they fold into complex three-dimensional structures and catalyze two transesterification reactions, thereby excising themselves and joining the flanking exons. These catalytic RNAs (ribozymes) have been modified previously to work in trans, whereby the ribozymes can recognize a splice site on a substrate RNA and replace the 5′- or 3′-portion of the substrate. Here we describe a new variant of the group I intron ribozyme from Tetrahymena that recognizes two splice sites on a substrate RNA, removes the intron sequences between the splice sites, and joins the flanking exons, analogous to the action of the spliceosome. This ‘group I spliceozyme’ functions in vitro and in vivo, and it is able to mediate a growth phenotype in E. coli cells. The intron sequences of the target pre-mRNAs are constrained near the splice sites but can carry a wide range of sequences in their interior. Because the splice site recognition sequences can be adjusted to different splice sites, the spliceozyme may have the potential for wide applications as tool in research and therapy.
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Affiliation(s)
- Zhaleh N. Amini
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Karen E. Olson
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Ulrich F. Müller
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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Carter JR, Keith JH, Fraser TS, Dawson JL, Kucharski CA, Horne KM, Higgs S, Fraser MJ. Effective suppression of dengue virus using a novel group-I intron that induces apoptotic cell death upon infection through conditional expression of the Bax C-terminal domain. Virol J 2014; 11:111. [PMID: 24927852 PMCID: PMC4104402 DOI: 10.1186/1743-422x-11-111] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 05/20/2014] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION Approximately 100 million confirmed infections and 20,000 deaths are caused by Dengue virus (DENV) outbreaks annually. Global warming and rapid dispersal have resulted in DENV epidemics in formally non-endemic regions. Currently no consistently effective preventive measures for DENV exist, prompting development of transgenic and paratransgenic vector control approaches. Production of transgenic mosquitoes refractory for virus infection and/or transmission is contingent upon defining antiviral genes that have low probability for allowing escape mutations, and are equally effective against multiple serotypes. Previously we demonstrated the effectiveness of an anti-viral group I intron targeting U143 of the DENV genome in mediating trans-splicing and expression of a marker gene with the capsid coding domain. In this report we examine the effectiveness of coupling expression of ΔN Bax to trans-splicing U143 intron activity as a means of suppressing DENV infection of mosquito cells. RESULTS Targeting the conserved DENV circularization sequence (CS) by U143 intron trans-splicing activity appends a 3' exon RNA encoding ΔN Bax to the capsid coding region of the genomic RNA, resulting in a chimeric protein that induces premature cell death upon infection. TCID50-IFA analyses demonstrate an enhancement of DENV suppression for all DENV serotypes tested over the identical group I intron coupled with the non-apoptotic inducing firefly luciferase as the 3' exon. These cumulative results confirm the increased effectiveness of this αDENV-U143-ΔN Bax group I intron as a sequence specific antiviral that should be useful for suppression of DENV in transgenic mosquitoes. Annexin V staining, caspase 3 assays, and DNA ladder observations confirm DCA-ΔN Bax fusion protein expression induces apoptotic cell death. CONCLUSION This report confirms the relative effectiveness of an anti-DENV group I intron coupled to an apoptosis-inducing ΔN Bax 3' exon that trans-splices conserved sequences of the 5' CS region of all DENV serotypes and induces apoptotic cell death upon infection. Our results confirm coupling the targeted ribozyme capabilities of the group I intron with the generation of an apoptosis-inducing transcript increases the effectiveness of infection suppression, improving the prospects of this unique approach as a means of inducing transgenic refractoriness in mosquitoes for all serotypes of this important disease.
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Affiliation(s)
| | | | | | | | | | | | | | - Malcolm J Fraser
- Department of Biological Sciences, Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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17
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Abstract
One of the major concerns with regard to successful cancer gene therapy is to enhance both efficacy and safety. Gene targeting may represent an attractive tool to combat cancer cells without damage to normal cells. Here, we introduce a tumor-targeting approach with the Tetrahymena group I intron-based trans-splicing ribozyme, which cleaves target RNA and trans-ligate an exon tagged at the end of the ribozyme onto the downstream U nucleotide of the cleaved target RNA. We develop a specific trans-splicing ribozyme that can target and reprogram human cytoskeleton-associate protein 2 (hCKAP2)-encoding RNA to trigger therapeutic transgene herpes simplex virus thymidine kinase (HSVtk) selectively in cancer cells that express the RNA. Adenoviral vectors encoding the hCKAP2-specific trans-splicing ribozyme are constructed for in vivo delivery into either subcutaneous tumor xenograft or orthotopically multifocal hepatocarcinoma. We present analyses of the efficacy of the recombinant adenoviral vectors in terms of cancer retardation, target RNA and cell specificity, and in vivo toxicity.
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Lee CH, Kim JH, Lee SW. Prospects for nucleic acid-based therapeutics against hepatitis C virus. World J Gastroenterol 2013; 19:8949-8962. [PMID: 24379620 PMCID: PMC3870548 DOI: 10.3748/wjg.v19.i47.8949] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 11/10/2013] [Accepted: 11/30/2013] [Indexed: 02/06/2023] Open
Abstract
In this review, we discuss recent advances in nucleic acid-based therapeutic technologies that target hepatitis C virus (HCV) infection. Because the HCV genome is present exclusively in RNA form during replication, various nucleic acid-based therapeutic approaches targeting the HCV genome, such as ribozymes, aptamers, siRNAs, and antisense oligonucleotides, have been suggested as potential tools against HCV. Nucleic acids are potentially immunogenic and typically require a delivery tool to be utilized as therapeutics. These limitations have hampered the clinical development of nucleic acid-based therapeutics. However, despite these limitations, nucleic acid-based therapeutics has clinical value due to their great specificity, easy and large-scale synthesis with chemical methods, and pharmaceutical flexibility. Moreover, nucleic acid therapeutics are expected to broaden the range of targetable molecules essential for the HCV replication cycle, and therefore they may prove to be more effective than existing therapeutics, such as interferon-α and ribavirin combination therapy. This review focuses on the current status and future prospects of ribozymes, aptamers, siRNAs, and antisense oligonucleotides as therapeutic reagents against HCV.
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Amini ZN, Müller UF. Low selection pressure aids the evolution of cooperative ribozyme mutations in cells. J Biol Chem 2013; 288:33096-106. [PMID: 24089519 DOI: 10.1074/jbc.m113.511469] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Understanding the evolution of functional RNA molecules is important for our molecular understanding of biology. Here we tested experimentally how two evolutionary parameters, selection pressure and recombination, influenced the evolution of an evolving RNA population. This was done using four parallel evolution experiments that employed low or gradually increasing selection pressure, and recombination events either at the end or dispersed throughout the evolution. As model system, a trans-splicing group I intron ribozyme was evolved in Escherichia coli cells over 12 rounds of selection and amplification, including mutagenesis and recombination. The low selection pressure resulted in higher efficiency of the evolved ribozyme populations, whereas differences in recombination did not have a strong effect. Five mutations were responsible for the highest efficiency. The first mutation swept quickly through all four evolving populations, whereas the remaining four mutations accumulated later and more efficiently under low selection pressure. To determine why low selection pressure aided this evolution, all evolutionary intermediates between the wild type and the 5-mutation variant were constructed, and their activities at three different selection pressures were determined. The resulting fitness profiles showed a high cooperativity among the four late mutations, which can explain why high selection pressure led to inefficient evolution. These results show experimentally how low selection pressure can benefit the evolution of cooperative mutations in functional RNAs.
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Affiliation(s)
- Zhaleh N Amini
- From the Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093
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20
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Lee CH, Lee YJ, Kim JH, Lim JH, Kim JH, Han W, Lee SH, Noh GJ, Lee SW. Inhibition of hepatitis C virus (HCV) replication by specific RNA aptamers against HCV NS5B RNA replicase. J Virol 2013; 87:7064-74. [PMID: 23596299 PMCID: PMC3676086 DOI: 10.1128/jvi.00405-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 04/09/2013] [Indexed: 12/15/2022] Open
Abstract
This study identified specific and avid RNA aptamers consisting of 2'-hydroxyl- or 2'-fluoropyrimidines against hepatitis C virus (HCV) NS5B replicase, an enzyme that is essential for HCV replication. These aptamers acted as potent decoys to competitively impede replicase-catalyzed RNA synthesis activity. Cytoplasmic expression of the 2'-hydroxyl aptamer efficiently inhibited HCV replicon replication in human liver cells through specific interaction with, and sequestration of, the target protein without either off-target effects or escape mutant generation. A selected 2'-fluoro aptamer could be truncated to a chemically manufacturable length of 29 nucleotides (nt), with increase in the affinity to HCV NS5B. Noticeably, transfection of the truncated aptamer efficiently suppressed HCV replication in cells without escape mutant appearance. The aptamer was further modified through conjugation of a cholesterol or galactose-polyethylene glycol ligand for in vivo availability and liver-specific delivery. The conjugated aptamer efficiently entered cells and inhibited genotype 1b subgenomic and genotype 2a full-length HCV JFH-1 RNA replication without toxicity and innate immunity induction. Importantly, a therapeutically feasible amount of the conjugated aptamer was delivered in vivo to liver tissue in mice. Therefore, cytoplasmic expression of 2'-hydroxyl aptamer or direct administration of chemically synthesized and ligand-conjugated 2'-fluoro aptamer against HCV NS5B could be a potent anti-HCV approach.
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Affiliation(s)
- Chang Ho Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
| | - Young Ju Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
| | - Ji Hyun Kim
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
| | - Jong Hoon Lim
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
| | - Jung-Hye Kim
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
| | | | - Soo-Han Lee
- Departments of Clinical Pharmacology and Therapeutics
| | - Gyu-Jeong Noh
- Departments of Clinical Pharmacology and Therapeutics
- Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Seong-Wook Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
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Abstract
Solid tumors form a heterogeneous group of diseases, although common features such as hyperproliferation, overexpression of certain growth factor receptors and deregulated vessel formation including leaky vasculature give the opportunity to target macromolecular drug and nucleic acid carriers to tumor tissue. Similar to other macromolecular drugs, nucleic acid carriers have to be designed to enable tumor targeting after systemic injection. Chemical modification of nucleic acids makes them resistant towards enzymatic degradation. Cationic lipids or polycations condense nucleic acids into small, virus-like structures and the surface modification with hydrophilic polymers allows passive accumulation in tumor tissue; tumor cell binding ligands allow cellular targeting. To avoid toxic side effects, biodegradable and biocompatible carriers were designed. The design of thermoresponsive gene carriers allowed their selective tumor accumulation by locoregional hyperthermia. As a therapeutic concept, tumor-specific delivery of antitumoral RNA was realized in an orthotopic brain tumor model. The combination of gene- and radio-therapy enabled selective accumulation of radionuclides in tumors and boosted antitumoral effects. Hence, combining a smart delivery concept for nucleic acids with a suitable therapeutic strategy will allow successful treatment of otherwise incurable malignant diseases.
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22
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Selective regression of cancer cells expressing a splicing variant of AIMP2 through targeted RNA replacement by trans-splicing ribozyme. J Biotechnol 2012; 158:44-9. [DOI: 10.1016/j.jbiotec.2012.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 12/21/2011] [Accepted: 01/10/2012] [Indexed: 11/20/2022]
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23
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Meluzzi D, Olson KE, Dolan GF, Arya G, Müller UF. Computational prediction of efficient splice sites for trans-splicing ribozymes. RNA (NEW YORK, N.Y.) 2012; 18:590-602. [PMID: 22274956 PMCID: PMC3285945 DOI: 10.1261/rna.029884.111] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 12/02/2011] [Indexed: 05/31/2023]
Abstract
Group I introns have been engineered into trans-splicing ribozymes capable of replacing the 3'-terminal portion of an external mRNA with their own 3'-exon. Although this design makes trans-splicing ribozymes potentially useful for therapeutic application, their trans-splicing efficiency is usually too low for medical use. One factor that strongly influences trans-splicing efficiency is the position of the target splice site on the mRNA substrate. Viable splice sites are currently determined using a biochemical trans-tagging assay. Here, we propose a rapid and inexpensive alternative approach to identify efficient splice sites. This approach involves the computation of the binding free energies between ribozyme and mRNA substrate. We found that the computed binding free energies correlate well with the trans-splicing efficiency experimentally determined at 18 different splice sites on the mRNA of chloramphenicol acetyl transferase. In contrast, our results from the trans-tagging assay correlate less well with measured trans-splicing efficiency. The computed free energy components suggest that splice site efficiency depends on the following secondary structure rearrangements: hybridization of the ribozyme's internal guide sequence (IGS) with mRNA substrate (most important), unfolding of substrate proximal to the splice site, and release of the IGS from the 3'-exon (least important). The proposed computational approach can also be extended to fulfill additional design requirements of efficient trans-splicing ribozymes, such as the optimization of 3'-exon and extended guide sequences.
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Affiliation(s)
- Dario Meluzzi
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, USA
- Department of NanoEngineering, University of California, San Diego, California 92093, USA
| | - Karen E. Olson
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, USA
| | - Gregory F. Dolan
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, USA
| | - Gaurav Arya
- Department of NanoEngineering, University of California, San Diego, California 92093, USA
| | - Ulrich F. Müller
- Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, USA
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24
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Olson KE, Müller UF. An in vivo selection method to optimize trans-splicing ribozymes. RNA (NEW YORK, N.Y.) 2012; 18:581-589. [PMID: 22274958 PMCID: PMC3285944 DOI: 10.1261/rna.028472.111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 12/01/2011] [Indexed: 05/31/2023]
Abstract
Group I intron ribozymes can repair mutated mRNAs by replacing the 3'-terminal portion of the mRNA with their own 3'-exon. This trans-splicing reaction has the potential to treat genetic disorders and to selectively kill cancer cells or virus-infected cells. However, these ribozymes have not yet been used in therapy, partially due to a low in vivo trans-splicing efficiency. Previous strategies to improve the trans-splicing efficiencies focused on designing and testing individual ribozyme constructs. Here we describe a method that selects the most efficient ribozymes from millions of ribozyme variants. This method uses an in vivo rescue assay where the mRNA of an inactivated antibiotic resistance gene is repaired by trans-splicing group I intron ribozymes. Bacterial cells that express efficient trans-splicing ribozymes are able to grow on medium containing the antibiotic chloramphenicol. We randomized a 5'-terminal sequence of the Tetrahymena thermophila group I intron and screened a library with 9 × 10⁶ ribozyme variants for the best trans-splicing activity. The resulting ribozymes showed increased trans-splicing efficiency and help the design of efficient trans-splicing ribozymes for different sequence contexts. This in vivo selection method can now be used to optimize any sequence in trans-splicing ribozymes.
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Affiliation(s)
- Karen E. Olson
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Ulrich F. Müller
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
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25
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Lee CH, Kim JH, Kim HW, Myung H, Lee SW. Hepatitis C virus replication-specific inhibition of microRNA activity with self-cleavable allosteric ribozyme. Nucleic Acid Ther 2012; 22:17-29. [PMID: 22217271 DOI: 10.1089/nat.2011.0326] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Functional sequestration of microRNA 122 (miR-122) by treatment with an oligonucleotide complementary to the miRNA results in long-lasting suppression of hepatitis C virus (HCV) viremia in primates. However, the safety of the constitutive miR-122 silencing approach to HCV inhibition is unclear, since miR-122 can modulate the expression of many host genes. In this study, a regulation system capable of specifically inhibiting miR-122 activity only upon HCV infection was developed. To this end, an allosteric self-cleavable ribozyme capable of releasing antisense sequence to miR-122 only in the presence of HCV nonstructural protein 5B was developed using in vitro selection method. The activity of the reporter construct with miR-122 target sequences at its 3' untranslated region and the expression of endogenous miR-122 target proteins were specifically stimulated through sequestration of miR-122 only in HCV replicon Huh-7 cells, but not in naïve Huh-7 cells, when transfected with expression vector encoding the specific allosteric ribozyme. These findings indicate that miR-122 function can be specifically inhibited by the allosteric ribozyme only in HCV-replicating cells. Importantly, HCV replicon replication was efficiently inhibited by the allosteric ribozyme. This ribozyme could be useful for the specific, safe, and efficacious anti-HCV modulation.
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Affiliation(s)
- Chang Ho Lee
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Yongin, Republic of Korea
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Ban G, Jeong JS, Kim A, Kim SJ, Han SY, Kim IH, Lee SW. Selective and efficient retardation of cancers expressing cytoskeleton-associated protein 2 by targeted RNA replacement. Int J Cancer 2011; 129:1018-29. [DOI: 10.1002/ijc.25988] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 01/21/2011] [Accepted: 02/02/2011] [Indexed: 11/10/2022]
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Carter JR, Keith JH, Barde PV, Fraser TS, Fraser MJ. Targeting of highly conserved Dengue virus sequences with anti-Dengue virus trans-splicing group I introns. BMC Mol Biol 2010; 11:84. [PMID: 21078188 PMCID: PMC3000392 DOI: 10.1186/1471-2199-11-84] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 11/15/2010] [Indexed: 11/11/2022] Open
Abstract
Background Dengue viruses (DENV) are one of the most important viral diseases in the world with approximately 100 million infections and 200,000 deaths each year. The current lack of an approved tetravalent vaccine and ineffective insecticide control measures warrant a search for alternatives to effectively combat DENV. The trans-splicing variant of the Tetrahymena thermophila group I intron catalytic RNA, or ribozyme, is a powerful tool for post-transcriptional RNA modification. The nature of the ribozyme and the predictability with which it can be directed makes it a powerful tool for modifying RNA in nearly any cell type without the need for genome-altering gene therapy techniques or dependence on native cofactors. Results Several anti-DENV Group I trans-splicing introns (αDENV-GrpIs) were designed and tested for their ability to target DENV-2 NGC genomes in situ. We have successfully targeted two different uracil bases on the positive sense genomic strand within the highly conserved 5'-3' cyclization sequence (CS) region common to all serotypes of DENV with our αDENV-GrpIs. Our ribozymes have demonstrated ability to specifically trans-splice a new RNA sequence downstream of the targeted site in vitro and in transfected insect cells as analyzed by firefly luciferase and RT-PCR assays. The effectiveness of these αDENV-GrpIs to target infecting DENV genomes is also validated in transfected or transformed Aedes mosquito cell lines upon infection with unattenuated DENV-2 NGC. Conclusions Analysis shows that our αDENV-GrpIs have the ability to effectively trans-splice the DENV genome in situ. Notably, these results show that the αDENV-GrpI 9v1, designed to be active against all forms of Dengue virus, effectively targeted the DENV-2 NGC genome in a sequence specific manner. These novel αDENV-GrpI introns provide a striking alternative to other RNA based approaches for the transgenic suppression of DENV in transformed mosquito cells and tissues.
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Affiliation(s)
- James R Carter
- Eck Institute for Global Health, Department of Biology, University of Notre Dame, Notre Dame, IN 46556, USA
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In vivo reprogramming of human telomerase reverse transcriptase (hTERT) by trans-splicing ribozyme to target tumor cells. Methods Mol Biol 2010; 629:307-21. [PMID: 20387158 DOI: 10.1007/978-1-60761-657-3_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Our understanding of RNA has evolved over the last 20 years from the initial concept that RNA is simply an intermediate in protein synthesis or a structural component maintaining and expressing genetic information. Subsequently, the non-coding RNAs have attracted huge interest and have been developed as therapeutic reagents as well as research tools. An example of RNA-based therapeutic application is the Tetrahymena group I intron-based trans-splicing ribozyme, which cleaves target RNA and trans-ligates an exon tagged at its 3' end onto the downstream U nucleotide of the targeted RNA. Here, we describe the specific trans-splicing ribozyme that can sense and reprogram human telomerase reverse transcriptase (hTERT)-encoding RNA. This ribozyme converts hTERT RNA to therapeutic transgene herpes simplex virus (HSV) thymidine kinase (tk) and exhibits cytotoxicity to various hTERT-expressing cancer cells. For use in cancer therapy, CMV promoter-driven hTERTRibozyme.HSVtk expression cassette is inserted into adenovirus genome and delivered into either subcutaneous or intraspleenic liver-metastasized xenograft. We present here an evaluation of the inhibitory effects of CMV.hTERTRibozyme.HSVtk on tumor growth.
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Chang B, Lee CH, Lee JH, Lee SW. Comparative analysis of intracellular inhibition of hepatitis C virus replication by small interfering RNAs. Biotechnol Lett 2010; 32:1231-7. [DOI: 10.1007/s10529-010-0298-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Accepted: 04/29/2010] [Indexed: 12/09/2022]
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30
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Fiskaa T, Birgisdottir AB. RNA reprogramming and repair based on trans-splicing group I ribozymes. N Biotechnol 2010; 27:194-203. [PMID: 20219714 DOI: 10.1016/j.nbt.2010.02.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
While many traditional gene therapy strategies attempt to deliver new copies of wild-type genes back to cells harboring the defective genes, RNA-directed strategies offer a range of novel therapeutic applications. Revision or reprogramming of mRNA is a form of gene therapy that modifies mRNA without directly changing the transcriptional regulation or the genomic gene sequence. Group I ribozymes can be engineered to act in trans by recognizing a separate RNA molecule in a sequence-specific manner, and to covalently link a new RNA sequence to this separate RNA molecule. Group I ribozymes have been shown to repair defective transcripts that cause human genetic or malignant diseases, as well as to replace transcript sequences by foreign RNA resulting in new cellular functions. This review provides an overview of current strategies using trans-splicing group I ribozymes in RNA repair and reprogramming.
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Affiliation(s)
- Tonje Fiskaa
- RNA and Transcriptomics Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway.
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31
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Song MS, Lee SW. RNA Mapping of Mutant Myotonic Dystrophy Protein Kinase 3'-Untranslated Region Transcripts. Genomics Inform 2009. [DOI: 10.5808/gi.2009.7.4.181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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So MK, Gowrishankar G, Hasegawa S, Chung JK, Rao J. Imaging Target mRNA and siRNA-Mediated Gene Silencing In Vivo with Ribozyme-Based Reporters. Chembiochem 2008; 9:2682-91. [DOI: 10.1002/cbic.200800370] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Song MS, Lee SW. In Vivo Target RNA Specificity of Trans-Splicing Phenomena by the Group I Intron. Genomics Inform 2008. [DOI: 10.5808/gi.2008.6.2.084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Hong SH, Jeong JS, Lee YJ, Jung HI, Cho KS, Kim CM, Kwon BS, Sullenger BA, Lee SW, Kim IH. In Vivo Reprogramming of hTERT by Trans-splicing Ribozyme to Target Tumor Cells. Mol Ther 2008; 16:74-80. [PMID: 17700543 DOI: 10.1038/sj.mt.6300282] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We have developed and validated a new tumor-targeting gene therapy strategy based upon the targeting and replacement of human telomerase reverse transcriptase (hTERT) RNA, using a trans-splicing ribozyme. By constructing novel adenoviral vectors harboring the hTERT-targeting trans-splicing ribozymes with the downstream reporter gene (Ad-Ribo-LacZ) or suicide gene (Ad-Ribo-HSVtk) driven by the cytomegalovirus (CMV) promoter, we demonstrated that this viral system selectively marks tumor cells expressing hTERT or sensitizes tumor cells to prodrug treatments. We confirmed that Ad-Ribo-LacZ successfully and selectively delivered a ribozyme that performed a highly specific trans-splicing reaction into hTERT-expressing cancer cells, both in vitro and in a peritoneal carcinomatosis nude mouse model. We also determined that the hTERT-specific expression of the suicide gene in the Ad-Ribo-HSVtk, and treatment with the corresponding prodrug, reduced tumor progression with almost the same efficacy as the strong constitutive CMV promoter-driven adenovirus, both in cancer cell lines and in nude mouse HT-29 xenografts. These observations provide the basis for a novel approach to cancer gene therapy, and demonstrate that trans-splicing ribozymes can be employed as targeting anti-cancer agents which recognize cancer-specific transcripts and reprogram them, thereby combating cancerous cells.
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Affiliation(s)
- Seung-Hee Hong
- Research Institute & Hospital, National Cancer Center, Goyang, South Korea
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35
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Yerly D, Di Giammarino L, Bihl F, Cerny A. Targets of emerging therapies for viral hepatitis B and C. Expert Opin Ther Targets 2007; 10:833-50. [PMID: 17105371 DOI: 10.1517/14728222.10.6.833] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Viral hepatitis B and C, structurally two completely different viruses, commonly infect human hepatocytes and cause similar clinical manifestations. Since their discovery, IFN has been a pillar in the treatment. However, because of the different natures of the viruses, therapeutic approaches diverge and new treatment targets are tailored specifically for each virus. Herein, the authors analyse therapeutic approaches for hepatitis B virus (HBV) and hepatitis C virus (HCV) and focus on emerging concepts that are under clinical evaluation. In particular, promising viral inhibitors for HBV and HCV are reviewed and the current status of research for gene therapy for HCV is described. Immune therapy is a fast-moving field with fascinating results which include therapeutic vaccines and toll-like receptor agonists that could improve tomorrow's treatment approaches.
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Affiliation(s)
- Daniel Yerly
- University of Bern, Clinic for Rheumatology and Clinical Immunology/Allergology, CH-3010 Bern, Switzerland
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36
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Kim A, Ban G, Song MS, Bae CD, Park J, Lee SW. Selective Regression of Cells Expressing Mouse Cytoskeleton-Associated Protein 2 Transcript by Trans-Splicing Ribozyme. Oligonucleotides 2007; 17:95-103. [PMID: 17461766 DOI: 10.1089/oli.2007.0044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cytoskeleton-associated protein 2 (CKAP2) is known to be highly expressed in primary human cancers as well as most cancer cell lines. CKAP2 functions as microtubule stabilizer and probably as cell proliferation inducer, indicating that CKAP2 might be a potential anticancer target. In this study, we developed a specific ribozyme that can replace mouse CKAP2 (mCKAP2) RNA with new transcripts through trans-splicing reaction. This specific RNA replacement resulted in triggering of transgene activity selectively in mammalian cells that express the mCKAP2 RNA. Simultaneously, the ribozyme reduced the expression level of the target RNA in the cells. Noticeably, the ribozyme selectively induced activity of the suicide gene herpes simplex virus thymidine kinase in cells expressing the mCKAP2 RNA and thereby specifically retarded the survival of these cells with ganciclovir treatment. This mCKAP2-specific ribozyme will be useful for validation of the RNA replacement as cancer gene therapy approach in mouse model with syngeneic tumors.
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Affiliation(s)
- Areum Kim
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Seoul 140-714, Korea
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37
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Abstract
Ribozymes are RNA molecules capable of associating with other RNA molecules through base-pairing and catalyzing various reactions involving phosphate group transfer. Of particular interest to us is the well known ribozyme from Tetrahymena thermophila capable of catalyzing RNA splicing in eukaryotic systems, chiefly because of its potential use as a gene therapy agent. In this article we review the progress made towards visualizing the RNA splicing mediated by the Tetrahymena ribozyme in single living mammalian cells with the beta-lactamase reporter system and highlight the development made in imaging RNA splicing with the luciferase reporter system in living animals.
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Affiliation(s)
- Gayatri Gowrishankar
- Molecular Imaging Program at Stanford, Department of Radiology & Bio-X Program, Cancer Biology Program, Stanford University School of Medicine, 1201 Welch Road, Stanford, California 94305-5484, USA.
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38
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Won YS, Lee SW. Targeted retardation of hepatocarcinoma cells by specific replacement of alpha-fetoprotein RNA. J Biotechnol 2007; 129:614-9. [PMID: 17360066 DOI: 10.1016/j.jbiotec.2007.02.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2006] [Revised: 01/16/2007] [Accepted: 02/07/2007] [Indexed: 10/23/2022]
Abstract
Although hepatocellular carcinoma (HCC) is one of the world-wide common malignancies, development of more specific and controlled therapeutic methods should be warranted. In this study, we describe a novel approach to HCC therapy that is based on trans-splicing ribozyme-mediated replacement of HCC-associated specific RNAs. We have developed a specific ribozyme that can target and replace human alpha-fetoprotein (AFP) RNA, which is highly expressed in HCC, with new transcript exerting therapeutic activity selectively in AFP-expressing liver cancer cells. The RNA replacement was employed via a high-fidelity trans-splicing reaction with the targeted residue in the AFP-expressing cells. Noticeably, the ribozyme could selectively deliver activity of suicide gene, herpes simplex virus thymidine kinase gene, into the liver cancer cells expressing the AFP RNA and thereby specifically and effectively retarded the survival of these cells with ganciclovir treatment. Simultaneously with the specific induction of therapeutic gene activity, the ribozyme reduced expression level of the targeted AFP RNA in the cells. These results suggest that the AFP RNA-targeting trans-splicing ribozyme could be a useful genetic agent for HCC-targeted efficient gene therapy.
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Affiliation(s)
- You-Sub Won
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, San8, Hannam-Dong, Yongsan-Gu, Seoul, Republic of Korea
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39
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Jung HS, Lee SW. Ribozyme-mediated selective killing of cancer cells expressing carcinoembryonic antigen RNA by targeted trans-splicing. Biochem Biophys Res Commun 2006; 349:556-63. [PMID: 16945335 DOI: 10.1016/j.bbrc.2006.08.073] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Accepted: 08/14/2006] [Indexed: 12/20/2022]
Abstract
Carcinoembryonic antigen (CEA) has been shown to be involved in a variety of neoplasia process, such as tumor cell adhesion, metastasis, blocking of cellular immune mechanisms, and anti-apoptosis function. Therefore, CEA has been a potential target for anti-cancer therapy. In this study, we developed a specific ribozyme that can target CEA RNA and then reprogram the RNA with new transcripts, resulting in triggering of transgene activity selectively in cancer cells that express the RNA. The ribozyme-mediated induction of the transgene expression was caused via a highly accurate and specific RNA replacement through trans-splicing reaction with the targeted residue in the CEA-expressing cells. Simultaneously with the specific RNA replacement, the ribozyme efficiently reduced expression level of the targeted CEA RNA in the cells. Importantly, the ribozyme could selectively deliver activity of suicide gene, herpes simplex virus thymidine kinase gene, into cancer cells expressing the CEA RNA and thereby specifically retarded the survival of these cells with ganciclovir treatment. These suggest that the CEA RNA-targeting trans-splicing ribozyme could be a powerful genetic agent for specific cancer gene therapy.
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Affiliation(s)
- Heung-Su Jung
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Seoul 140-714, Republic of Korea
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40
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Song MS, Lee SW. Cancer-selective induction of cytotoxicity by tissue-specific expression of targetedtrans-splicing ribozyme. FEBS Lett 2006; 580:5033-43. [PMID: 16949075 DOI: 10.1016/j.febslet.2006.08.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Revised: 07/18/2006] [Accepted: 08/04/2006] [Indexed: 10/24/2022]
Abstract
For suicide gene therapy to be successfully applied for clinical settings, cancer-restricted expression of such suicide gene should be required. We previously showed that group I intron from Tetrahymena can induce new RNA that exerts anti-cancer activity through RNA replacement by trans-splicing reaction with high fidelity and specificity onto targeted human telomerase reverse transcriptase (hTERT) RNA in cancer cells, and hence the ribozyme can selectively retard growth of the cells in vivo as well as in vitro. However, the shortage of complete tumor-selectivity due to telomerase expression of highly proliferating normal cells can limit therapeutic applicability of the hTERT-targeting approach. In this study, to explore the possibility of improving specificity of cancer therapy, we have attempted to stimulate anticancer gene activity specifically in liver cancer cells by tissue-specific expression of the hTERT-targeting trans-splicing ribozyme using liver-specific promoters. Transient transfection experiments demonstrated that the expression of transgene such as luciferase gene was specifically and highly triggered from hTERT-expressing liver cancer cells transfected with the ribozyme. Moreover, liver-specific expression of the ribozyme with diphtheria toxin A or herpes simplex virus thymidine kinase gene as 3' exon could specifically and highly retard the growth of the hTERT-expressing liver cancer cells. In conclusion, we can greatly improve specificity of cancer cytotoxicity by combination of transcriptional targeting for tissue-specific transgene expression with RNA replacement for cancer-specific anticancer gene induction.
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Affiliation(s)
- Min-Sun Song
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, San8 Hannam-Dong, Yongsan-Gu, Seoul 140-714, Republic of Korea
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41
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Fiskaa T, Lundblad EW, Henriksen JR, Johansen SD, Einvik C. RNA reprogramming of α-mannosidase mRNA sequencesin vitroby myxomycete group IC1 and IE ribozymes. FEBS J 2006; 273:2789-800. [PMID: 16817905 DOI: 10.1111/j.1742-4658.2006.05295.x] [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: 11/30/2022]
Abstract
Trans-splicing group I ribozymes have been introduced in order to mediate RNA reprogramming (including RNA repair) of therapeutically relevant RNA transcripts. Efficient RNA reprogramming depends on the appropriate efficiency of the reaction, and several attempts, including optimization of target recognition and ribozyme catalysis, have been performed. In most studies, the Tetrahymena group IC1 ribozyme has been applied. Here we investigate the potential of group IC1 and group IE intron ribozymes, derived from the myxomycetes Didymium and Fuligo, in addition to the Tetrahymena ribozyme, for RNA reprogramming of a mutated alpha-mannosidase mRNA sequence. Randomized internal guide sequences were introduced for all four ribozymes and used to select accessible sites within isolated mutant alpha-mannosidase mRNA from mammalian COS-7 cells. Two accessible sites common to all the group I ribozymes were identified and further investigated in RNA reprogramming by trans-splicing analyses. All the myxomycete ribozymes performed the trans-splicing reaction with high fidelity, resulting in the conversion of mutated alpha-mannosidase RNA into wild-type sequence. RNA protection analysis revealed that the myxomycete ribozymes perform trans-splicing at approximately similar efficiencies as the Tetrahymena ribozyme. Interestingly, the relative efficiency among the ribozymes tested correlates with structural features of the P4-P6-folding domain, consistent with the fact that efficient folding is essential for group I intron trans-splicing.
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Affiliation(s)
- Tonje Fiskaa
- Department of Molecular Biotechnology, RNA Research group, Institute of Medical Biology, University of Tromsø, Norway
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42
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Mitchell LG, McGarrity GJ. Gene therapy progress and prospects: reprograming gene expression by trans-splicing. Gene Ther 2006; 12:1477-85. [PMID: 16121205 DOI: 10.1038/sj.gt.3302596] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The term 'trans-splicing' encompasses several platform technologies that combine two RNA or protein molecules to generate a new, chimeric product. RNA trans-splicing reprograms the sequences of endogenous messenger mRNA or pre-mRNA, converting them to a new, desired gene product. Trans-splicing has broad applications, depending on the nature of the sequences that are inserted or trans-spliced to the defined target. Trans-splicing RNA therapy offers significant advantages over conventional gene therapy: expression of the trans-spliced sequence is controlled by the endogenous regulation of the target pre-mRNA; reduction or elimination of undesirable ectopic expression; the ability to use smaller constructs that trans-splice only a portion of the gene to be replaced; and the conversion of dominant-negative mutations to wild-type gene products.
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43
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Kwon BS, Jung HS, Song MS, Cho KS, Kim SC, Kimm K, Jeong JS, Kim IH, Lee SW. Specific Regression of Human Cancer Cells by Ribozyme-Mediated Targeted Replacement of Tumor-Specific Transcript. Mol Ther 2005; 12:824-34. [PMID: 16040278 DOI: 10.1016/j.ymthe.2005.06.096] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2004] [Revised: 06/08/2005] [Accepted: 06/19/2005] [Indexed: 10/25/2022] Open
Abstract
In this study, we describe a novel approach to human cancer therapy that is based upon trans-splicing ribozyme-mediated replacement of cancer-specific RNAs with new transcripts that exert therapeutic activities. We have developed a specific ribozyme that can reprogram human telomerase reverse transcriptase (hTERT) RNA to induce transgene activity selectively in cancer cells that express the RNA. The ribozyme-mediated triggering of the transgene expression was accomplished via a high-fidelity trans-splicing reaction with the targeted residue in the hTERT-expressing cells. The ribozyme also induced cytotoxic activity in various hTERT-expressing cancer cells, hence selectively retarding the growth of those cells. Efficient and specific cell regression was also detected with ganciclovir (GCV) treatment only in hTERT-positive cancer cells, which were established to express stably the specific ribozyme that contains the herpes simplex virus thymidine kinase (HSV-tk) gene. Tissue-specific expression of the ribozyme could further augment the target specificity of the ribozyme. Importantly, we observed efficient regression of tumors with GCV treatment in mice that had been inoculated subcutaneously with hTERT-positive cancer cells that stably expressed the specific ribozyme that contains HSV-tk. These results suggest that the hTERT RNA-targeting trans-splicing ribozyme could be a powerful agent for tumor-targeted specific gene therapy.
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Affiliation(s)
- Byung-Su Kwon
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Seoul 140-714, Korea
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44
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Chen Z, Zheng M. Patents and development of HBV and HCV clinical treatment: from 2001 to April 2005. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.15.8.1027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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45
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Abstract
Recombination is widespread among RNA viruses, but many molecular mechanisms of this phenomenon are still poorly understood. It was believed until recently that the only possible mechanism of RNA recombination is replicative template switching, with synthesis of a complementary strand starting on one viral RNA molecule and being completed on another. The newly synthesized RNA is a primary recombinant molecule in this case. Recent studies have revealed other mechanisms of replicative RNA recombination. In addition, recombination between the genomes of RNA viruses can be nonreplicative, resulting from a joining of preexisting parental molecules. Recombination is a potent tool providing for both the variation and conservation of the genome in RNA viruses. Replicative and nonreplicative mechanisms may contribute differently to each of these evolutionary processes. In the form of trans splicing, nonreplicative recombination of cell RNAs plays an important role in at least some organisms. It is conceivable that RNA recombination continues to contribute to the evolution of DNA genomes.
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Affiliation(s)
- A P Gmyl
- 1Chumakov Institute of Poliomyelitis and Viral Encephalites, Russian Academy of Medical Sciences, Moscow Region, 142782 Russia
| | - V I Agol
- 1Chumakov Institute of Poliomyelitis and Viral Encephalites, Russian Academy of Medical Sciences, Moscow Region, 142782 Russia.,2Moscow State University, Moscow, 119992 Russia
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46
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Baum DA, Testa SM. In vivo excision of a single targeted nucleotide from an mRNA by a trans excision-splicing ribozyme. RNA (NEW YORK, N.Y.) 2005; 11:897-905. [PMID: 15872183 PMCID: PMC1370774 DOI: 10.1261/rna.2050505] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Accepted: 03/02/2005] [Indexed: 05/02/2023]
Abstract
We have previously reported the development of a group I intron-derived ribozyme that can bind an exogenous RNA substrate and excise from that substrate an internal segment in vitro, which allows for sequence-specific modification of RNA molecules. In this report, the activity of this trans excision-splicing ribozyme in a cellular environment, specifically Escherichia coli, was investigated. The ribozyme was re-engineered to target for excision a single-base insertion in the transcript of a green fluorescent protein, and fluorescence was exploited as a reporter for trans excision-splicing. We show that the ribozyme is able to catalyze the trans excision-splicing reaction in vivo and can repair the mutant transcripts. On average, 12% correction is observed as measured by fluorescence and at least 0.6% correction as confirmed through sequence analysis. This represents the first report of a biomolecule (in this case a ribozyme) that can selectively excise a targeted nucleotide from within an mRNA transcript in vivo. This new class of biochemical tools makes possible a wide variety of new experimental strategies, perhaps including a new approach to molecular-based therapeutics.
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Affiliation(s)
- Dana A Baum
- Department of Chemistry, University of Kentucky, Lexington, 40506, USA
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47
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Jung HS, Kwon BS, Lee SW. Tumor-specific gene delivery using RNA-targeting Tetrahymena group I intron. Biotechnol Lett 2005; 27:567-74. [PMID: 15973491 DOI: 10.1007/s10529-005-2883-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 02/17/2005] [Accepted: 02/18/2005] [Indexed: 11/29/2022]
Abstract
Current gene therapy protocols against cancer often have limited target specificity. Here, a novel tumor-specific targeted gene delivery procedure, which is based on Tetrahymena group I intron ribozyme, is presented. This ribozyme can target a cancer-specific transcript and then replace the RNA with new transcripts, resulting in induction of the transgene activity selectively in cancer cells that express the target RNA. The RNA replacement occurs by trans-splicing reaction with high fidelity with the target RNA. In addition, the ribozyme can specifically inhibit function of the targeted gene in the cells expressing the RNA. Moreover, the ribozyme can selectively deliver cytotoxin gene activity into cancer cells expressing the RNA and thereby specifically hampers the survival of these cells. These findings suggest that the trans-splicing ribozyme that targets the cancer-specific RNA could be a potential agent for specific tumor gene therapy.
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Affiliation(s)
- Heung-Su Jung
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, Seoul, 140-714, Korea
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48
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Shin KS, Sullenger BA, Lee SW. Ribozyme-mediated induction of apoptosis in human cancer cells by targeted repair of mutant p53 RNA. Mol Ther 2005; 10:365-72. [PMID: 15294183 DOI: 10.1016/j.ymthe.2004.05.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Accepted: 05/03/2004] [Indexed: 10/26/2022] Open
Abstract
A variety of mutations in the p53 tumor suppressor gene have been found in over half of human tumors. Thus, restoration of wild-type p53 activity by repair of mutant RNA has been previously suggested as an approach to cancer treatment. To explore the potential utility of RNA repair for cancer therapy, we developed a group I intron-based ribozyme that can replace mutant p53 RNA with a wild-type RNA sequence attached to the 3' end of the ribozyme by trans-splicing reaction. First, RNA mapping analysis demonstrated that the leader sequences upstream of the AUG start codon in the mutant p53 RNA appeared to be particularly accessible to the ribozymes. Then, the trans-splicing ribozyme specifically recognizing the most accessible sequence induced functional p53 activity, resulting in an 8- and a 2.6-fold induction of transactivation of p53-responsive promoters in two mutant p53-related ovarian cancer cell lines, SKOV3 cells and 2774 cells, respectively, by repairing defective p53 RNA. The repair efficiency of the mutant p53 RNA was almost 10% in 2774 cells. Moreover, the ribozyme activated the expression level of endogenous p21 and Bax genes in the cells. Furthermore, apoptosis was efficiently triggered in the human cancer cells transfected with the specific ribozyme. These results suggest that a trans-splicing ribozyme could be a potent anti-cancer agent that can revert the defective p53-related neoplastic phenotype.
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Affiliation(s)
- Kyung-Sook Shin
- Institute of Nanosensor and Biotechnology, Department of Molecular Biology, Dankook University, Seoul, South Korea
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49
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Pergolizzi RG, Crystal RG. Genetic medicine at the RNA level: modifications of the genetic repertoire for therapeutic purposes by pre-mRNA trans-splicing. C R Biol 2004; 327:695-709. [PMID: 15506518 DOI: 10.1016/j.crvi.2004.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Gene therapy is conventionally carried out by transferring genetic material to the target cell where the exogenous gene is expressed using the endogenous transcription and translation machinery in parallel with the target cell genome. This review focuses on a new paradigm of gene therapy, the use of trans-splicing to modify the genetic repertoire at the pre-mRNA level to treat genetic and acquired disorders. Therapeutic trans-splicing can be used to alter coding domains, to create novel fusion proteins, to direct gene products to various cellular compartments, and to overcome some of the limitations to vector-derived gene transfer technology, including gene therapy with large genes or with genes coding for toxic proteins. To demonstrate the potential of therapeutic trans-splicing, eukaryotic cis-splicing and trans-splicing are reviewed, followed by a discussion of strategies of therapeutic pre-mRNA trans-splicing directed by exogenous gene transfer.
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Affiliation(s)
- Robert G Pergolizzi
- Department of Genetic Medicine, Weill Medical College of Cornell University, 515 East 71st Street, S-1000 New York, NY 10021, USA
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50
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N/A. N/A. Shijie Huaren Xiaohua Zazhi 2004; 12:2757-2761. [DOI: 10.11569/wcjd.v12.i11.2757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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