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Eisenhut P, Marx N, Borsi G, Papež M, Ruggeri C, Baumann M, Borth N. Manipulating gene expression levels in mammalian cell factories: An outline of synthetic molecular toolboxes to achieve multiplexed control. N Biotechnol 2024; 79:1-19. [PMID: 38040288 DOI: 10.1016/j.nbt.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/06/2023] [Accepted: 11/26/2023] [Indexed: 12/03/2023]
Abstract
Mammalian cells have developed dedicated molecular mechanisms to tightly control expression levels of their genes where the specific transcriptomic signature across all genes eventually determines the cell's phenotype. Modulating cellular phenotypes is of major interest to study their role in disease or to reprogram cells for the manufacturing of recombinant products, such as biopharmaceuticals. Cells of mammalian origin, for example Chinese hamster ovary (CHO) and Human embryonic kidney 293 (HEK293) cells, are most commonly employed to produce therapeutic proteins. Early genetic engineering approaches to alter their phenotype have often been attempted by "uncontrolled" overexpression or knock-down/-out of specific genetic factors. Many studies in the past years, however, highlight that rationally regulating and fine-tuning the strength of overexpression or knock-down to an optimum level, can adjust phenotypic traits with much more precision than such "uncontrolled" approaches. To this end, synthetic biology tools have been generated that enable (fine-)tunable and/or inducible control of gene expression. In this review, we discuss various molecular tools used in mammalian cell lines and group them by their mode of action: transcriptional, post-transcriptional, translational and post-translational regulation. We discuss the advantages and disadvantages of using these tools for each cell regulatory layer and with respect to cell line engineering approaches. This review highlights the plethora of synthetic toolboxes that could be employed, alone or in combination, to optimize cellular systems and eventually gain enhanced control over the cellular phenotype to equip mammalian cell factories with the tools required for efficient production of emerging, more difficult-to-express biologics formats.
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Affiliation(s)
- Peter Eisenhut
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria
| | - Nicolas Marx
- BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria.
| | - Giulia Borsi
- BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria
| | - Maja Papež
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria; BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria
| | - Caterina Ruggeri
- BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria
| | - Martina Baumann
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria
| | - Nicole Borth
- Austrian Centre of Industrial Biotechnology (acib GmbH), Muthgasse 11, 1190 Vienna, Austria; BOKU University of Natural Resources and Life Sciences, Institute of Animal Cell Technology and Systems Biology, Muthgasse 18, 1190 Vienna, Austria.
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2
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Ding Y, Tous C, Choi J, Chen J, Wong WW. Orthogonal inducible control of Cas13 circuits enables programmable RNA regulation in mammalian cells. Nat Commun 2024; 15:1572. [PMID: 38383558 PMCID: PMC10881482 DOI: 10.1038/s41467-024-45795-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 02/06/2024] [Indexed: 02/23/2024] Open
Abstract
RNA plays an indispensable role in mammalian cell functions. Cas13, a class of RNA-guided ribonuclease, is a flexible tool for modifying and regulating coding and non-coding RNAs, with enormous potential for creating new cell functions. However, the lack of control over Cas13 activity has limited its cell engineering capability. Here, we present the CRISTAL (Control of RNA with Inducible SpliT CAs13 Orthologs and Exogenous Ligands) platform. CRISTAL is powered by a collection (10 total) of orthogonal split inducible Cas13 effectors that can be turned ON or OFF via small molecules in multiple cell types, providing precise temporal control. Also, we engineer Cas13 logic circuits that can respond to endogenous signaling and exogenous small molecule inputs. Furthermore, the orthogonality, low leakiness, and high dynamic range of our inducible Cas13d and Cas13b enable the design and construction of a robust incoherent feedforward loop, leading to near-perfect and tunable adaptation response. Finally, using our inducible Cas13 effectors, we achieve simultaneous multiplexed control of multiple genes in vitro and in mice. Together, our CRISTAL design represents a powerful platform for precisely regulating RNA dynamics to advance cell engineering and elucidate RNA biology.
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Affiliation(s)
- Yage Ding
- Department of Biomedical Engineering, Biological Design Center, Boston University, Boston, MA, 2215, USA
| | - Cristina Tous
- Department of Biomedical Engineering, Biological Design Center, Boston University, Boston, MA, 2215, USA
| | - Jaehoon Choi
- Department of Biomedical Engineering, Biological Design Center, Boston University, Boston, MA, 2215, USA
| | - Jingyao Chen
- Department of Biomedical Engineering, Biological Design Center, Boston University, Boston, MA, 2215, USA
| | - Wilson W Wong
- Department of Biomedical Engineering, Biological Design Center, Boston University, Boston, MA, 2215, USA.
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3
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Takahashi K, Galloway KE. RNA-based controllers for engineering gene and cell therapies. Curr Opin Biotechnol 2024; 85:103026. [PMID: 38052131 PMCID: PMC11214845 DOI: 10.1016/j.copbio.2023.103026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/12/2023] [Accepted: 11/14/2023] [Indexed: 12/07/2023]
Abstract
Engineered RNA-based genetic controllers provide compact, tunable, post-transcriptional gene regulation. As RNA devices are generally small, these devices are portable to DNA and RNA viral vectors. RNA tools have recently expanded to allow reading and editing of endogenous RNAs for profiling and programming of transcriptional states. With their expanded capabilities and highly compact, modular, and programmable nature, RNA-based controllers will support greater safety, efficacy, and performance in gene and cell-based therapies. In this review, we highlight RNA-based controllers and their potential as user-guided and autonomous systems for control of gene and cell-based therapies.
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Affiliation(s)
- Kei Takahashi
- Department of Chemical Engineering, MIT, 25 Ames St., Cambridge, MA 02139, USA
| | - Kate E Galloway
- Department of Chemical Engineering, MIT, 25 Ames St., Cambridge, MA 02139, USA.
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Kishimoto T, Nishimura K, Morishita K, Fukuda A, Miyamae Y, Kumagai Y, Sumaru K, Nakanishi M, Hisatake K, Sano M. An engineered ligand-responsive Csy4 endoribonuclease controls transgene expression from Sendai virus vectors. J Biol Eng 2024; 18:9. [PMID: 38229076 DOI: 10.1186/s13036-024-00404-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 01/04/2024] [Indexed: 01/18/2024] Open
Abstract
BACKGROUND Viral vectors are attractive gene delivery vehicles because of their broad tropism, high transduction efficiency, and durable expression. With no risk of integration into the host genome, the vectors developed from RNA viruses such as Sendai virus (SeV) are especially promising. However, RNA-based vectors have limited applicability because they lack a convenient method to control transgene expression by an external inducer. RESULTS We engineered a Csy4 switch in Sendai virus-based vectors by combining Csy4 endoribonuclease with mutant FKBP12 (DD: destabilizing domain) that becomes stabilized when a small chemical Shield1 is supplied. In this Shield1-responsive Csy4 (SrC) switch, Shield1 increases Csy4 fused with DD (DD-Csy4), which then cleaves and downregulates the transgene mRNA containing the Csy4 recognition sequence (Csy4RS). Moreover, when Csy4RS is inserted in the viral L gene, the SrC switch suppresses replication and transcription of the SeV vector in infected cells in a Shield1-dependent manner, thus enabling complete elimination of the vector from the cells. By temporally controlling BRN4 expression, a BRN4-expressing SeV vector equipped with the SrC switch achieves efficient, stepwise differentiation of embryonic stem cells into neural stem cells, and then into astrocytes. CONCLUSION SeV-based vectors with the SrC switch should find wide applications in stem cell research, regenerative medicine, and gene therapy, especially when precise control of reprogramming factor expression is desirable.
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Grants
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
- JP19H03203, JP19K22945, JP19K07343, JP21H02678, JP19K06501 Japan Society for the Promotion of Science
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Affiliation(s)
- Takumi Kishimoto
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
- Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Ken Nishimura
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
| | - Kana Morishita
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Aya Fukuda
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
| | - Yusaku Miyamae
- Institute of Life and Environment Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Yutaro Kumagai
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Kimio Sumaru
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Mahito Nakanishi
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
- TOKIWA-Bio, Inc, 2-1-6 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - Koji Hisatake
- Laboratory of Gene Regulation, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
| | - Masayuki Sano
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan.
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Kläge D, Müller E, Hartig JS. A comparative survey of the influence of small self-cleaving ribozymes on gene expression in human cell culture. RNA Biol 2024; 21:1-11. [PMID: 38146121 PMCID: PMC10761166 DOI: 10.1080/15476286.2023.2296203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2023] [Indexed: 12/27/2023] Open
Abstract
Self-cleaving ribozymes are versatile tools for synthetic biologists when it comes to controlling gene expression. Up to date, 12 different classes are known, and over the past decades more and more details about their structure, cleavage mechanisms and natural environments have been uncovered. However, when these motifs are applied to mammalian gene expression constructs, the outcome can often be unexpected. A variety of factors, such as surrounding sequences and positioning of the ribozyme influences the activity and hence performance of catalytic RNAs. While some information about the efficiency of individual ribozymes (each tested in specific contexts) is known, general trends obtained from standardized, comparable experiments are lacking, complicating decisions such as which ribozyme to choose and where to insert it into the target mRNA. In many cases, application-specific optimization is required, which can be very laborious. Here, we systematically compared different classes of ribozymes within the 3'-UTR of a given reporter gene. We then examined position-dependent effects of the best-performing ribozymes. Moreover, we tested additional variants of already widely used hammerhead ribozymes originating from various organisms. We were able to identify functional structures suited for aptazyme design and generated highly efficient hammerhead ribozyme variants originating from the human genome. The present dataset will aide decisions about how to apply ribozymes for affecting gene expression as well as for developing ribozyme-based switches for controlling gene expression in human cells.
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Affiliation(s)
- Dennis Kläge
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Konstanz, Germany
| | - Elisabeth Müller
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Konstanz, Germany
| | - Jörg S. Hartig
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Konstanz, Germany
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Zheng Z, Wu X, Wang Y, Yang X, Chen H, Shen Y, Yang Y, Xia Q. Attenuating RNA Viruses with Expanded Genetic Codes to Evoke Adjustable Immune Response in PylRS-tRNACUAPyl Transgenic Mice. Vaccines (Basel) 2023; 11:1606. [PMID: 37897007 PMCID: PMC10610612 DOI: 10.3390/vaccines11101606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/03/2023] [Accepted: 09/24/2023] [Indexed: 10/29/2023] Open
Abstract
Ribonucleic acid (RNA) viruses pose heavy burdens on public-health systems. Synthetic biology holds great potential for artificially controlling their replication, a strategy that could be used to attenuate infectious viruses but is still in the exploratory stage. Herein, we used the genetic-code expansion technique to convert Enterovirus 71 (EV71), a prototypical RNA virus, into a controllable EV71 strain carrying the unnatural amino acid (UAA) Nε-2-azidoethyloxycarbonyl-L-lysine (NAEK), which we termed an EV71-NAEK virus. After NAEK supplementation, EV71-NAEK could recapitulate an authentic NAEK time- and dose-dependent infection in vitro, which could serve as a novel method to manipulate virulent viruses in conventional laboratories. We further validated the prophylactic effect of EV71-NAEK in two mouse models. In susceptible parent mice, vaccination with EV71-NAEK elicited a strong immune response and protected their neonatal offspring from lethal challenges similar to that of commercial vaccines. Meanwhile, in transgenic mice harboring a PylRS-tRNACUAPyl pair, substantial elements of genetic-code expansion technology, EV71-NAEK evoked an adjustable neutralizing-antibody response in a strictly external NAEK dose-dependent manner. These findings suggested that EV71-NAEK could be the basis of a feasible immunization program for populations with different levels of immunity. Moreover, we expanded the strategy to generate controllable coxsackieviruses for conceptual verification. In combination, these results could underlie a competent strategy for attenuating viruses and priming the immune system via artificial control, which might be a promising direction for the development of amenable vaccine candidates and be broadly applied to other RNA viruses.
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Affiliation(s)
| | | | | | | | | | | | | | - Qing Xia
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; (Z.Z.); (X.W.); (Y.W.); (X.Y.); (H.C.); (Y.S.); (Y.Y.)
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7
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Fan Z, Dou CX, Tang LJ, Wang F, Jiang JH. Genetically Encoded RNA Sensors for Ratiometric and Multiplexed Imaging of Small Molecules in Living Cells. Anal Chem 2023; 95:14455-14464. [PMID: 37699117 DOI: 10.1021/acs.analchem.3c03027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Genetically encoded sensors afford powerful tools for studying small molecules and metabolites in live cells. However, genetically encoded sensors with a general design remain to be developed. Here we develop genetically encoded RNA sensors with a modular design for ratiometric and multiplexed imaging of small molecules in live cells. The sensor utilizes aptazyme as a recognition module and the light-up RNA aptamer as a signal reporter. The conformation of light-up aptamers is abrogated by a blocking sequence, and aptazyme-mediated cleavage restores the correct conformation, delivering activated fluorescence for small molecule imaging. We first developed a genetically encoded ratiometric sensor using Mango aptamer as a reference and SRB2 as a reporter. It is shown that the sensor allows quantitative imaging and detection of theophylline in live cells. The generality of the design is further demonstrated for imaging other small molecules by replacing the aptazymes. Its ability for multiplexed imaging of small molecules is further explored via the integration of different small-molecule responsive aptazymes and light-up RNA aptamers. This modular design could offer a versatile platform for imaging diverse molecules in living cells.
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Affiliation(s)
- Ze Fan
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Cai-Xia Dou
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Li-Juan Tang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Fenglin Wang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Jian-Hui Jiang
- State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
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8
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van der Meulen K, Smets G, Rüdelsheim P. Viral Replicon Systems and Their Biosafety Aspects. APPLIED BIOSAFETY 2023; 28:102-122. [PMID: 37342518 PMCID: PMC10278005 DOI: 10.1089/apb.2022.0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2023]
Abstract
Introduction Viral RNA replicons are self-amplifying RNA molecules generated by deleting genetic information of one or multiple structural proteins of wild-type viruses. Remaining viral RNA is used as such (naked replicon) or packaged into a viral replicon particle (VRP), whereby missing genes or proteins are supplied via production cells. Since replicons mostly originate from pathogenic wild-type viruses, careful risk consideration is crucial. Methods A literature review was performed compiling information on potential biosafety risks of replicons originating from positive- and negative-sense single-stranded RNA viruses (except retroviruses). Results For naked replicons, risk considerations included genome integration, persistence in host cells, generation of virus-like vesicles, and off-target effects. For VRP, the main risk consideration was formation of primary replication competent virus (RCV) as a result of recombination or complementation. To limit the risks, mostly measures aiming at reducing the likelihood of RCV formation have been described. Also, modifying viral proteins in such a way that they do not exhibit hazardous characteristics in the unlikely event of RCV formation has been reported. Discussion and Conclusion Despite multiple approaches developed to reduce the likelihood of RCV formation, scientific uncertainty remains on the actual contribution of the measures and on limitations to test their effectiveness. In contrast, even though effectiveness of each individual measure is unclear, using multiple measures on different aspects of the system may create a solid barrier. Risk considerations identified in the current study can also be used to support risk group assignment of replicon constructs based on a purely synthetic design.
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9
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Ding Y, Tous C, Choi J, Chen J, Wong WW. Orthogonal inducible control of Cas13 circuits enables programmable RNA regulation in mammalian cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533499. [PMID: 36993327 PMCID: PMC10055290 DOI: 10.1101/2023.03.20.533499] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
RNA plays an indispensable role in mammalian cell functions. Cas13, a class of RNA-guided ribonuclease, is a flexible tool for modifying and regulating coding and non-coding RNAs, with enormous potential for creating new cell functions. However, the lack of control over Cas13 activity has limited its cell engineering capability. Here, we present the CRISTAL ( C ontrol of R NA with Inducible S pli T C A s13 Orthologs and Exogenous L igands) platform. CRISTAL is powered by a collection (10 total) of orthogonal split inducible Cas13s that can be turned ON or OFF via small molecules in multiple cell types, providing precise temporal control. Also, we engineered Cas13 logic circuits that can respond to endogenous signaling and exogenous small molecule inputs. Furthermore, the orthogonality, low leakiness, and high dynamic range of our inducible Cas13d and Cas13b enable the design and construction of a robust incoherent feedforward loop, leading to near-perfect and tunable adaptation response. Finally, using our inducible Cas13s, we achieve simultaneous multiplexed control of multiple genes in vitro and in mice. Together, our CRISTAL design represents a powerful platform for precisely regulating RNA dynamics to advance cell engineering and elucidate RNA biology.
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10
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Kumar A, Baldia A, Rajput D, Kateriya S, Babu V, Dubey KK. Multiomics and optobiotechnological approaches for the development of microalgal strain for production of aviation biofuel and biorefinery. BIORESOURCE TECHNOLOGY 2023; 369:128457. [PMID: 36503094 DOI: 10.1016/j.biortech.2022.128457] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/02/2022] [Accepted: 12/04/2022] [Indexed: 06/17/2023]
Abstract
Demand and consumption of fossil fuels is increasing daily, and oil reserves are depleting. Technological developments are required towards developing sustainable renewable energy sources and microalgae are emerging as a potential candidate for various application-driven research. Molecular understanding attained through omics and system biology approach empowering researchers to modify various metabolic pathways of microalgal system for efficient extraction of biofuel and important biomolecules. This review furnish insight into different "advanced approaches" like optogenetics, systems biology and multi-omics for enhanced production of FAS (Fatty Acid Synthesis) and lipids in microalgae and their associated challenges. These new approaches would be helpful in the path of developing microalgae inspired technological platforms for optobiorefinery, which could be explored as source material to produce biofuels and other valuable bio-compounds on a large scale.
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Affiliation(s)
- Akshay Kumar
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Anshu Baldia
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Deepanshi Rajput
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Suneel Kateriya
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Vikash Babu
- Fermentation & Microbial Biotechnology Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180001, India
| | - Kashyap Kumar Dubey
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
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11
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Eriksson RAE, Nieminen T, Galibert L, Peltola SK, Tikkanen P, Käyhty P, Lesch HP, Ylä-Herttuala S, Airenne KJ. Optimized riboswitch-regulated AAV vector for VEGF-B gene therapy. Front Med (Lausanne) 2022; 9:1052318. [PMID: 36582287 PMCID: PMC9792491 DOI: 10.3389/fmed.2022.1052318] [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: 09/23/2022] [Accepted: 11/24/2022] [Indexed: 12/15/2022] Open
Abstract
Gene therapy would greatly benefit from a method to regulate therapeutic gene expression temporally. Riboswitches are small RNA elements that have been studied for their potential use in turning transgene expression on or off by ligand binding. We compared several tetracycline and toyocamycin-inducible ON-riboswitches for a drug responsive transgene expression. The tetracycline-dependent K19 riboswitch showed the best control and we successfully applied it to different transgenes. The induction of gene expression was 6- to 10-fold, dose-dependent, reversible, and occurred within hours after the addition of a clinically relevant tetracycline dose, using either plasmid or adeno-associated virus (AAV) vectors. To enhance the switching capacity, we further optimized the gene cassette to control the expression of a potential therapeutic gene for cardiovascular diseases, VEGF-B. Using two or three riboswitches simultaneously reduced leakiness and improved the dynamic range, and a linker sequence between the riboswitches improved their functionality. The riboswitch function was promoter-independent, but a post-transcriptional WPRE element in the expression cassette reduced its functionality. The optimized construct was a dual riboswitch at the 3' end of the transgene with a 100 bp linker sequence. Our study reveals significant differences in the function of riboswitches and provides important aspects on optimizing expression cassette designs. The findings will benefit further research and development of riboswitches.
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Affiliation(s)
- Reetta A E Eriksson
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland.,A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Tiina Nieminen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | | | | | - Petra Tikkanen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Piia Käyhty
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland.,A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Hanna P Lesch
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Seppo Ylä-Herttuala
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.,Gene Therapy Unit and Research Center, Kuopio University Hospital, Kuopio, Finland
| | - Kari J Airenne
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
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12
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Kim N, Yokobayashi Y. Novel RNA Viral Vectors for Chemically Regulated Gene Expression in Embryonic Stem Cells. ACS Synth Biol 2021; 10:2959-2967. [PMID: 34676762 DOI: 10.1021/acssynbio.1c00214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
RNA viral vectors that replicate without DNA intermediates are attractive platforms for manipulation of cells for biomedical and veterinary applications because they have minimal risk of chromosomal integration. Vesicular stomatitis virus (VSV) vectors are among the most well-studied RNA viral vectors due to their low pathogenicity to humans and ability to express transgenes at high levels for weeks to months. However, their applications have been mostly limited to oncolytic and vaccine vectors due to their cytopathogenicity. We discovered two mutations in the VSV vector that synergistically confer improved stability in mouse embryonic stem cells (ESCs) with markedly lower cytopathic effects. We also demonstrated chemical regulation of transgene expression through embedded riboswitches. The ESCs infected with the mutant vector were shown to maintain pluripotency. This new vector sets the stage for precise regulation of gene expression in ESCs to produce a variety of differentiated cells without chromosomal alteration.
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Affiliation(s)
- Narae Kim
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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13
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Tabuchi T, Yokobayashi Y. Cell-free riboswitches. RSC Chem Biol 2021; 2:1430-1440. [PMID: 34704047 PMCID: PMC8496063 DOI: 10.1039/d1cb00138h] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/26/2021] [Indexed: 12/16/2022] Open
Abstract
The emerging community of cell-free synthetic biology aspires to build complex biochemical and genetic systems with functions that mimic or even exceed those in living cells. To achieve such functions, cell-free systems must be able to sense and respond to the complex chemical signals within and outside the system. Cell-free riboswitches can detect chemical signals via RNA-ligand interaction and respond by regulating protein synthesis in cell-free protein synthesis systems. In this article, we review synthetic cell-free riboswitches that function in both prokaryotic and eukaryotic cell-free systems reported to date to provide a current perspective on the state of cell-free riboswitch technologies and their limitations.
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Affiliation(s)
- Takeshi Tabuchi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University Onna Okinawa 904-0495 Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University Onna Okinawa 904-0495 Japan
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14
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Engineering Aptazyme Switches for Conditional Gene Expression in Mammalian Cells Utilizing an In Vivo Screening Approach. Methods Mol Biol 2021. [PMID: 34086282 DOI: 10.1007/978-1-0716-1499-0_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Artificial RNA switches are an emerging class of genetic controllers suitable for synthetic biology applications. Aptazymes are fusions composed of an aptamer domain and a self-cleaving ribozyme. The utilization of aptazymes for conditional gene expression displays several advantages over employing conventional transcription factor-based techniques as aptazymes require minimal genomic space, fulfill their function without the need of protein cofactors and most importantly are reprogrammable with respect to ligand selectivity and the RNA function to be regulated. Technologies that enable the generation of aptazymes to defined input ligands are of interest for the construction of biocomputing devices and biosensing applications. In this chapter we present a method that facilitates the in vivo screening of randomized pools of aptazymes in mammalian cells.
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15
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Khakhar A, Wang C, Swanson R, Stokke S, Rizvi F, Sarup S, Hobbs J, Voytas DF. VipariNama: RNA viral vectors to rapidly elucidate the relationship between gene expression and phenotype. PLANT PHYSIOLOGY 2021; 186:2222-2238. [PMID: 34009393 PMCID: PMC8331131 DOI: 10.1093/plphys/kiab197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 04/01/2021] [Indexed: 05/05/2023]
Abstract
Synthetic transcription factors have great promise as tools to help elucidate relationships between gene expression and phenotype by allowing tunable alterations of gene expression without genomic alterations of the loci being studied. However, the years-long timescales, high cost, and technical skill associated with plant transformation have limited their use. In this work, we developed a technology called VipariNama (ViN) in which vectors based on the tobacco rattle virus are used to rapidly deploy Cas9-based synthetic transcription factors and reprogram gene expression in planta. We demonstrate that ViN vectors can implement activation or repression of multiple genes systemically and persistently over several weeks in Nicotiana benthamiana, Arabidopsis (Arabidopsis thaliana), and tomato (Solanum lycopersicum). By exploring strategies including RNA scaffolding, viral vector ensembles, and viral engineering, we describe how the flexibility and efficacy of regulation can be improved. We also show how this transcriptional reprogramming can create predictable changes to metabolic phenotypes, such as gibberellin biosynthesis in N. benthamiana and anthocyanin accumulation in Arabidopsis, as well as developmental phenotypes, such as plant size in N. benthamiana, Arabidopsis, and tomato. These results demonstrate how ViN vector-based reprogramming of different aspects of gibberellin signaling can be used to engineer plant size in a range of plant species in a matter of weeks. In summary, ViN accelerates the timeline for generating phenotypes from over a year to just a few weeks, providing an attractive alternative to transgenesis for synthetic transcription factor-enabled hypothesis testing and crop engineering.
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Affiliation(s)
- Arjun Khakhar
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
| | - Cecily Wang
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
| | - Ryan Swanson
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
| | - Sydney Stokke
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
| | - Furva Rizvi
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
| | - Surbhi Sarup
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
| | - John Hobbs
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
| | - Daniel F Voytas
- Department Genetics, Cell Biology, & Development, University of Minnesota, Minneapolis 55108, USA
- Center for Precision Plant Genomics, University of Minnesota, St Paul, Minneapolis 55108, USA
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16
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Krüger A, de Jesus Santos AP, de Sá V, Ulrich H, Wrenger C. Aptamer Applications in Emerging Viral Diseases. Pharmaceuticals (Basel) 2021; 14:ph14070622. [PMID: 34203242 PMCID: PMC8308861 DOI: 10.3390/ph14070622] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 02/07/2023] Open
Abstract
Aptamers are single-stranded DNA or RNA molecules which are submitted to a process denominated SELEX. SELEX uses reiterative screening of a random oligonucleotide library to identify high-affinity binders to a chosen target, which may be a peptide, protein, or entire cells or viral particles. Aptamers can rival antibodies in target recognition, and benefit from their non-proteic nature, ease of modification, increased stability, and pharmacokinetic properties. This turns them into ideal candidates for diagnostic as well as therapeutic applications. Here, we review the recent accomplishments in the development of aptamers targeting emerging viral diseases, with emphasis on recent findings of aptamers binding to coronaviruses. We focus on aptamer development for diagnosis, including biosensors, in addition to aptamer modifications for stabilization in body fluids and tissue penetration. Such aptamers are aimed at in vivo diagnosis and treatment, such as quantification of viral load and blocking host cell invasion, virus assembly, or replication, respectively. Although there are currently no in vivo applications of aptamers in combating viral diseases, such strategies are promising for therapy development in the future.
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Affiliation(s)
- Arne Krüger
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000-SP, Brazil;
| | - Ana Paula de Jesus Santos
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-900-SP, Brazil; (A.P.d.J.S.); (V.d.S.)
| | - Vanessa de Sá
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-900-SP, Brazil; (A.P.d.J.S.); (V.d.S.)
| | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-900-SP, Brazil; (A.P.d.J.S.); (V.d.S.)
- Correspondence: (H.U.); (C.W.)
| | - Carsten Wrenger
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-000-SP, Brazil;
- Correspondence: (H.U.); (C.W.)
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17
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Heilmann E, Kimpel J, Hofer B, Rössler A, Blaas I, Egerer L, Nolden T, Urbiola C, Kräusslich HG, Wollmann G, von Laer D. Chemogenetic ON and OFF switches for RNA virus replication. Nat Commun 2021; 12:1362. [PMID: 33649317 PMCID: PMC7921684 DOI: 10.1038/s41467-021-21630-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 02/03/2021] [Indexed: 11/09/2022] Open
Abstract
Therapeutic application of RNA viruses as oncolytic agents or gene vectors requires a tight control of virus activity if toxicity is a concern. Here we present a regulator switch for RNA viruses using a conditional protease approach, in which the function of at least one viral protein essential for transcription and replication is linked to autocatalytical, exogenous human immunodeficiency virus (HIV) protease activity. Virus activity can be en- or disabled by various HIV protease inhibitors. Incorporating the HIV protease dimer in the genome of vesicular stomatitis virus (VSV) into the open reading frame of either the P- or L-protein resulted in an ON switch. Here, virus activity depends on co-application of protease inhibitor in a dose-dependent manner. Conversely, an N-terminal VSV polymerase tag with the HIV protease dimer constitutes an OFF switch, as application of protease inhibitor stops virus activity. This technology may also be applicable to other potentially therapeutic RNA viruses.
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Affiliation(s)
- E Heilmann
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
- Christian Doppler Laboratory for Viral Immunotherapy of Cancer, Medical University of Innsbruck, Innsbruck, Austria
| | - J Kimpel
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
| | - B Hofer
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
| | - A Rössler
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
| | - I Blaas
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
| | - L Egerer
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
- ViraTherapeutics GmbH, Innsbruck, Austria
| | - T Nolden
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
- ViraTherapeutics GmbH, Innsbruck, Austria
| | - C Urbiola
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria
- Christian Doppler Laboratory for Viral Immunotherapy of Cancer, Medical University of Innsbruck, Innsbruck, Austria
- ViraTherapeutics GmbH, Innsbruck, Austria
| | - H G Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
- German Center for Infectious Disease Research, partner site Heidelberg, Heidelberg, Germany
| | - G Wollmann
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria.
- Christian Doppler Laboratory for Viral Immunotherapy of Cancer, Medical University of Innsbruck, Innsbruck, Austria.
| | - D von Laer
- Institute of Virology, Medical University of Innsbruck, Innsbruck, Austria.
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18
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Brayshaw LL, Martinez-Fleites C, Athanasopoulos T, Southgate T, Jespers L, Herring C. The role of small molecules in cell and gene therapy. RSC Med Chem 2021; 12:330-352. [PMID: 34046619 PMCID: PMC8130622 DOI: 10.1039/d0md00221f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/25/2020] [Indexed: 01/22/2023] Open
Abstract
Cell and gene therapies have achieved impressive results in the treatment of rare genetic diseases using gene corrected stem cells and haematological cancers using chimeric antigen receptor T cells. However, these two fields face significant challenges such as demonstrating long-term efficacy and safety, and achieving cost-effective, scalable manufacturing processes. The use of small molecules is a key approach to overcome these barriers and can benefit cell and gene therapies at multiple stages of their lifecycle. For example, small molecules can be used to optimise viral vector production during manufacturing or used in the clinic to enhance the resistance of T cell therapies to the immunosuppressive tumour microenvironment. Here, we review current uses of small molecules in cell and gene therapy and highlight opportunities for medicinal chemists to further consolidate the success of cell and gene therapies.
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Affiliation(s)
- Lewis L Brayshaw
- Cell & Gene Therapy Discovery Research, Medicinal Science & Technology, GlaxoSmithKline Medicines Research Centre Gunnels Wood Road Stevenage SG1 2NY UK
| | - Carlos Martinez-Fleites
- Protein Degradation Group, Medicinal Science & Technology, GlaxoSmithKline Medicines Research Centre Gunnels Wood Road Stevenage SG1 2NY UK
| | - Takis Athanasopoulos
- Cell & Gene Therapy Discovery Research, Medicinal Science & Technology, GlaxoSmithKline Medicines Research Centre Gunnels Wood Road Stevenage SG1 2NY UK
| | - Thomas Southgate
- Cell & Gene Therapy Discovery Research, Medicinal Science & Technology, GlaxoSmithKline Medicines Research Centre Gunnels Wood Road Stevenage SG1 2NY UK
| | - Laurent Jespers
- Cell & Gene Therapy Discovery Research, Medicinal Science & Technology, GlaxoSmithKline Medicines Research Centre Gunnels Wood Road Stevenage SG1 2NY UK
| | - Christopher Herring
- Cell & Gene Therapy Discovery Research, Medicinal Science & Technology, GlaxoSmithKline Medicines Research Centre Gunnels Wood Road Stevenage SG1 2NY UK
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19
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Measles Virus as an Oncolytic Immunotherapy. Cancers (Basel) 2021; 13:cancers13030544. [PMID: 33535479 PMCID: PMC7867054 DOI: 10.3390/cancers13030544] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/19/2021] [Accepted: 01/26/2021] [Indexed: 12/11/2022] Open
Abstract
Measles virus (MeV) preferentially replicates in malignant cells, leading to tumor lysis and priming of antitumor immunity. Live attenuated MeV vaccine strains are therefore under investigation as cancer therapeutics. The versatile MeV reverse genetics systems allows for engineering of advanced targeted, armed, and shielded oncolytic viral vectors. Therapeutic efficacy can further be enhanced by combination treatments. An emerging focus in this regard is combination immunotherapy, especially with immune checkpoint blockade. Despite challenges arising from antiviral immunity, availability of preclinical models, and GMP production, early clinical trials have demonstrated safety of oncolytic MeV and yielded promising efficacy data. Future clinical trials with engineered viruses, rational combination regimens, and comprehensive translational research programs will realize the potential of oncolytic immunotherapy.
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20
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Parra-Rojas C, Fürtig B, Schwalbe H, Hernandez-Vargas EA. Quantitative modeling of the function of kinetically driven transcriptional riboswitches. J Theor Biol 2020; 506:110406. [PMID: 32771533 DOI: 10.1016/j.jtbi.2020.110406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 06/17/2020] [Accepted: 07/09/2020] [Indexed: 11/18/2022]
Abstract
Riboswitches are cis-acting regulatory mRNA elements in bacteria, that modulate the expression of their associated genes in response to a cognate metabolite, operating either on the level of translation or transcription. Transcriptional riboswitches have to fold into functional structures as they are being synthesized and, only if transcription rates and ligand binding kinetics match, structured transcription intermediates are enabled to undergo ligand-dependent conformational refolding as a prerequisite for ligand-mediated gene expression. Therefore, transcription rates are of essential importance for functional riboswitch-mediated gene regulation. Here, we propose a generalized modeling framework for the kinetic mechanisms of transcriptional riboswitches. The formalism accommodates time-dependent transcription rates and changes of metabolite concentration and permits incorporation of variations in transcription rate depending on transcript length. We derive explicit analytical expressions for the fraction of transcripts that determine repression or activation of gene expression as a function of pause site location and its slowing down of transcription for the case of the (2'dG)-sensing riboswitch from Mesoplasma florum. Our modeling challenges the current view on the exclusive importance of metabolite binding to transcripts containing only the aptamer domain. Numerical simulations of transcription proceeding in a continuous manner under time-dependent changes of metabolite concentration further suggest that rapid modulations in concentration result in a reduced dynamic range for riboswitch function regardless of transcription rate, while a combination of slow modulations and small transcription rates ensures a wide range of finely tuneable regulatory outcomes.
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Affiliation(s)
- César Parra-Rojas
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany
| | - Boris Fürtig
- Institute for Organic Chemistry and Chemical Biology Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität, 60438 Frankfurt am Main, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität, 60438 Frankfurt am Main, Germany.
| | - Esteban A Hernandez-Vargas
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany; Instituto de Matemáticas, Universidad Nacional Autonoma de Mexico, Boulevard Juriquilla 3001, Santiago de Querétaro, Qro. 76230, Mexico.
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21
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Leber MF, Neault S, Jirovec E, Barkley R, Said A, Bell JC, Ungerechts G. Engineering and combining oncolytic measles virus for cancer therapy. Cytokine Growth Factor Rev 2020; 56:39-48. [PMID: 32718830 PMCID: PMC7333629 DOI: 10.1016/j.cytogfr.2020.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 07/02/2020] [Indexed: 12/18/2022]
Abstract
Cancer immunotherapy using tumor-selective, oncolytic viruses is an emerging therapeutic option for solid and hematologic malignancies. A considerable variety of viruses ranging from small picornaviruses to large poxviruses are currently being investigated as potential candidates. In the early days of virotherapy, non-engineered wild-type or vaccine-strain viruses were employed. However, these viruses often did not fully satisfy the major criteria of safety and efficacy. Since the advent of reverse genetics systems for manipulating various classes of viruses, the field has shifted to developing genetically engineered viruses with an improved therapeutic index. In this review, we will summarize the concepts and strategies of multi-level genetic engineering of oncolytic measles virus, a prime candidate for cancer immunovirotherapy. Furthermore, we will provide a brief overview of measles virus-based multimodal combination therapies for improved tumor control and clinical efficacy.
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Affiliation(s)
- Mathias F Leber
- German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany; Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada.
| | - Serge Neault
- Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada
| | - Elise Jirovec
- Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada
| | - Russell Barkley
- Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada
| | - Aida Said
- Children's Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada; University of Ottawa, Faculty of Medicine, Department of Cellular and Molecular Medicine, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada
| | - John C Bell
- Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada
| | - Guy Ungerechts
- German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany; Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada
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22
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Mühlebach MD. Measles virus in cancer therapy. Curr Opin Virol 2020; 41:85-97. [PMID: 32861945 DOI: 10.1016/j.coviro.2020.07.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 07/24/2020] [Accepted: 07/27/2020] [Indexed: 02/07/2023]
Abstract
Over the last years, the development of viruses to treat cancer patients has re-gained considerable attention. A genetically modified herpesvirus, Talimogene laherparepvec, has already been authorized for the treatment of melanoma patients. Also recombinant measles virus (MeV) is developed as an oncolytic virus. Because of its high genetic flexibility, a number of different MeV strains have been the basis for the generation of targeted, armed, or shielded viruses that are highly specific for a given tumor target, more effective, or protected against serum neutralization. Such MeV have been extensively tested in vitro and in vivo, whereby remarkable oncolytic potency is accompanied by safety also in non-human primates. Therefore, MeV has been introduced into 19 different clinical trials and has reached phase II against two different tumor entities, multiple myeloma and ovarian carcinoma. Remarkably, one patient with advanced stage myeloma experienced long-term remission after treatment, visualizing the potency of this approach.
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Affiliation(s)
- Michael D Mühlebach
- Division of Veterinary Medicine, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
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23
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Strobel B, Düchs MJ, Blazevic D, Rechtsteiner P, Braun C, Baum-Kroker KS, Schmid B, Ciossek T, Gottschling D, Hartig JS, Kreuz S. A Small-Molecule-Responsive Riboswitch Enables Conditional Induction of Viral Vector-Mediated Gene Expression in Mice. ACS Synth Biol 2020; 9:1292-1305. [PMID: 32427483 DOI: 10.1021/acssynbio.9b00410] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adeno-associated viral (AAV) vector-mediated gene therapy holds great potential for future medical applications. However, to facilitate safer and broader applicability and to enable patient-centric care, therapeutic protein expression should be controllable, ideally by an orally administered drug. The use of protein-based systems is considered rather undesirable, due to potential immunogenicity and the limited coding space of AAV. Ligand-dependent riboswitches, in contrast, are small and characterized by an attractive mode-of-action based on mRNA-self-cleavage, independent of coexpressed foreign protein. While a promising approach, switches available to date have only shown moderate potency in animals. In particular, ON-switches that induce transgene expression upon ligand administration so far have achieved rather disappointing results. Here we present the utilization of the previously described tetracycline-dependent ribozyme K19 for controlling AAV-mediated transgene expression in mice. Using this tool switch, we provide first proof for the feasibility of clinically desired key features, including multiorgan functionality, potent regulation (up to 15-fold induction), reversibility, and the possibility to fine-tune and repeatedly induce expression. The systematic assessment of ligand and reporter protein plasma levels further enabled the characterization of pharmacokinetic-pharmacodynamic relationships. Thus, our results strongly support future efforts to develop engineered riboswitches for applications in clinical gene therapy.
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Affiliation(s)
- Benjamin Strobel
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Matthias J. Düchs
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Dragica Blazevic
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Philipp Rechtsteiner
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Clemens Braun
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Katja S. Baum-Kroker
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Bernhard Schmid
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Thomas Ciossek
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Dirk Gottschling
- Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
| | - Jörg S. Hartig
- Department of Chemistry, University of Konstanz, Konstanz, 78464, Germany
| | - Sebastian Kreuz
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, 88397, Germany
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24
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Wrist A, Sun W, Summers RM. The Theophylline Aptamer: 25 Years as an Important Tool in Cellular Engineering Research. ACS Synth Biol 2020; 9:682-697. [PMID: 32142605 DOI: 10.1021/acssynbio.9b00475] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The theophylline aptamer was isolated from an oligonucleotide library in 1994. Since that time, the aptamer has found wide utility, particularly in synthetic biology, cellular engineering, and diagnostic applications. The primary application of the theophylline aptamer is in the construction and characterization of synthetic riboswitches for regulation of gene expression. These riboswitches have been used to control cellular motility, regulate carbon metabolism, construct logic gates, screen for mutant enzymes, and control apoptosis. Other applications of the theophylline aptamer in cellular engineering include regulation of RNA interference and genome editing through CRISPR systems. Here we describe the uses of the theophylline aptamer for cellular engineering over the past 25 years. In so doing, we also highlight important synthetic biology applications to control gene expression in a ligand-dependent manner.
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Affiliation(s)
- Alexandra Wrist
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Wanqi Sun
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Ryan M. Summers
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States
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25
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Pu Q, Zhou S, Huang X, Yuan Y, Du F, Dong J, Chen G, Cui X, Tang Z. Intracellular Selection of Theophylline-Sensitive Hammerhead Aptazyme. MOLECULAR THERAPY. NUCLEIC ACIDS 2020; 20:400-408. [PMID: 32244167 PMCID: PMC7118274 DOI: 10.1016/j.omtn.2020.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 02/14/2020] [Accepted: 03/10/2020] [Indexed: 12/14/2022]
Abstract
Hammerhead ribozyme-based aptazyme (HHAz), inheriting the advantages of small size and high efficiency from the RNA-cleaving ribozyme and the specific recognition ability of aptamers to specific targets, exhibits the huge potential to be a transgene expression regulator. Herein, we report a selection strategy for HHAz by using a toxin protein IbsC as the reporter to offer a positive phenotype, thus realizing an easy-operating, time- and labor-saving selection of HHAz variants with desired properties. Based on this strategy, we obtained a new HHAz (TAP-1), which could react sensitively toward the extracellular regulatory molecule, theophylline, both in prokaryotic and eukaryotic systems. With fluorescent protein reporter, the intracellular switching efficiencies of TAP-1 and other reported theophylline-dependent HHAzs has been quantitatively evaluated, showing that TAP-1 not only exhibits the best downregulating ability at high concentration of theophylline but also maintains high activity with 0.1 mM theophylline, which is a safe concentration in the human body.
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Affiliation(s)
- Qinlin Pu
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China; University of Chinese Academy of Sciences, Beijing 10049, P.R. China
| | - Shan Zhou
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China; University of Chinese Academy of Sciences, Beijing 10049, P.R. China
| | - Xin Huang
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China
| | - Yi Yuan
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China
| | - Feng Du
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China
| | - Juan Dong
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China
| | - Gangyi Chen
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China
| | - Xin Cui
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China
| | - Zhuo Tang
- Natural Products Research Center, Chengdu Institution of Biology, Chinese Academy of Science, Chengdu 610041, P.R. China.
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26
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Leber MF, Hoyler B, Prien S, Neault S, Engeland CE, Förster JM, Bossow S, Springfeld C, von Kalle C, Jäger D, Bell JC, Ungerechts G. Sequencing of serially passaged measles virus affirms its genomic stability and reveals a nonrandom distribution of consensus mutations. J Gen Virol 2020; 101:399-409. [PMID: 32053093 DOI: 10.1099/jgv.0.001395] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Oncolytic virotherapy is an emerging treatment option for numerous cancers, with several virus families currently being evaluated in clinical trials. More specifically, vaccine-strain measles virus has arisen as a promising candidate for the treatment of different tumour types in several early clinical trials. Replicating viruses, and especially RNA viruses without proofreading polymerases, can rapidly adapt to varying environments by selecting quasispecies with advantageous genetic mutations. Subsequently, these genetic alterations could potentially weaken the safety profile of virotherapy. In this study, we demonstrate that, following an extended period of virus replication in producer or cancer cell lines, the quasispecies consensus sequence of vaccine strain-derived measles virus accrues a remarkably small number of mutations throughout the nonsegmented negative-stranded RNA genome. Interestingly, we detected a nonrandom distribution of genetic alterations within the genome, with an overall decreasing frequency of mutations from the 3' genome start to its 5' end. Comparing the serially passaged viruses to the parental virus on producer cells, we found that the acquired consensus mutations did not drastically change viral replication kinetics or cytolytic potency. Collectively, our data corroborate the genomic stability and excellent safety profile of oncolytic measles virus, thus supporting its continued development and clinical translation as a promising viro-immunotherapeutic.
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Affiliation(s)
- Mathias Felix Leber
- German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.,Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany.,Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada
| | - Birgit Hoyler
- Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany.,German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Stefanie Prien
- Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany.,German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Serge Neault
- Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada
| | - Christine E Engeland
- Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany.,German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Judith M Förster
- Heidelberg University, Faculty of Biosciences, Im Neuenheimer Feld 234, 69120 Heidelberg, Germany.,German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Sascha Bossow
- Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany
| | - Christoph Springfeld
- Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany
| | - Christof von Kalle
- Sidra Medical and Research Center, Al Luqta Street, Education City, North Campus, 26999, Doha, Qatar.,Berlin Institute of Health and Charité, Universitätsmedizin, Anna-Louisa-Karsch-Straße 2, 10178 Berlin, Germany.,German Cancer Research Center (DKFZ), Division of Translational Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany
| | - Dirk Jäger
- Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany
| | - John C Bell
- Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada
| | - Guy Ungerechts
- Ottawa Hospital Research Institute, Cancer Therapeutics Program, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada.,Heidelberg University Hospital, Department of Medical Oncology, Im Neuenheimer Feld 460, 69120 Heidelberg, Germany.,German Cancer Research Center (DKFZ), Clinical Cooperation Unit Virotherapy, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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27
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Mustafina K, Fukunaga K, Yokobayashi Y. Design of Mammalian ON-Riboswitches Based on Tandemly Fused Aptamer and Ribozyme. ACS Synth Biol 2020; 9:19-25. [PMID: 31820936 DOI: 10.1021/acssynbio.9b00371] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Self-cleaving ribozymes engineered to be activated or inhibited by a small molecule binding to an RNA aptamer inserted within a ribozyme (aptazymes) have proven to be useful for controlling gene expression in living cells. In mammalian cells, an aptazyme embedded in the 5' or 3' untranslated region of an mRNA functions as a synthetic riboswitch to chemically regulate gene expression. However, the variety of aptazyme architectures and the ribozyme scaffolds that have been used for mammalian riboswitches has been limited. In particular, fewer synthetic riboswitches that activate gene expression in response to a small molecule (ON-switches) in mammalian cells have been reported compared to OFF-switches. In this work, we developed mammalian riboswitches that function as guanine-activated ON-switches based on a novel aptazyme architecture in which an aptamer and a ribozyme are fused in tandem. The riboswitch performance was optimized by fine-tuning the stability of a critical stem that controls the ribozyme structure and function, yielding switches with ON/OFF ratios greater than 6.0. Our new aptazyme architecture expands the RNA device toolbox for controlling gene expression in mammalian cells.
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Affiliation(s)
- Kamila Mustafina
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Keisuke Fukunaga
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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28
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Yamamoto Y, Tomonaga K, Honda T. Development of an RNA Virus-Based Episomal Vector Capable of Switching Transgene Expression. Front Microbiol 2019; 10:2485. [PMID: 31781052 PMCID: PMC6851019 DOI: 10.3389/fmicb.2019.02485] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 10/15/2019] [Indexed: 01/16/2023] Open
Abstract
Viral vectors are efficient gene delivery systems, although most of these vectors still present limitations to their practical use, such as achieving only transient transgene expression and a risk of insertional mutations. We have recently developed an RNA virus-based episomal vector (REVec), based on nuclear-replicating Borna disease virus (BoDV). REVec can transduce transgenes into various types of cells and stably express transgenes; however, an obstacle to the practical use of REVec is the lack of a mechanism to turn off transgene expression once REVec is transduced. Here, we developed a novel REVec system, REVec-L2b9, in which transgene expression can be switched on and off by using a theophylline-dependent self-cleaving riboswitch. Transgene expression from REVec-L2b9 was suppressed in the absence of theophylline and induced by theophylline administration. Conversely, transgene expression from REVec-L2b9 was switched off by removing theophylline. To our knowledge, REVec-L2b9 is the first nuclear-replicating RNA virus vector capable of switching transgene expression on and off as needed, which will expand the potential for gene therapies by increasing safety and usability.
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Affiliation(s)
- Yusuke Yamamoto
- Laboratory of RNA Viruses, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto, Japan.,Laboratory of RNA Viruses, Graduate School of Biostudies, Kyoto, Japan
| | - Keizo Tomonaga
- Laboratory of RNA Viruses, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto, Japan.,Laboratory of RNA Viruses, Graduate School of Biostudies, Kyoto, Japan.,Department of Molecular Virology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tomoyuki Honda
- Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, Osaka, Japan
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29
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Takahashi K, Yokobayashi Y. Reversible Gene Regulation in Mammalian Cells Using Riboswitch-Engineered Vesicular Stomatitis Virus Vector. ACS Synth Biol 2019; 8:1976-1982. [PMID: 31415142 DOI: 10.1021/acssynbio.9b00177] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Synthetic riboswitches based on small molecule-responsive self-cleaving ribozymes (aptazymes) embedded in the untranslated regions (UTRs) allow chemical control of gene expression in mammalian cells. In this work, we used a guanine-responsive aptazyme to control transgene expression from a replication-incompetent vesicular stomatitis virus (VSV) vector. VSV is a nonsegmented, negative-sense, cytoplasmic RNA virus that replicates without DNA intermediates, and its applications for vaccines and oncolytic viral therapy are being explored. By inserting the guanine-activated ribozyme in the 3' UTRs of viral genes and transgenes, GFP expression from the VSV vector in mammalian cells was repressed by as much as 26.8-fold in the presence of guanine. Furthermore, we demonstrated reversible regulation of a transgene (secreted NanoLuc) by adding and withdrawing guanine from the medium over the course of 12 days. In summary, our riboswitch-controlled VSV vector allows robust, long-term, and reversible regulation of gene expression in mammalian cells without the risk of undesirable genomic integration.
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Affiliation(s)
- Kei Takahashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
| | - Yohei Yokobayashi
- Nucleic Acid Chemistry and Engineering Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904 0495, Japan
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30
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Haines MC, Storch M, Oyarzún DA, Stan GB, Baldwin GS. Riboswitch identification using Ligase-Assisted Selection for the Enrichment of Responsive Ribozymes (LigASERR). Synth Biol (Oxf) 2019; 4:ysz019. [PMID: 32995542 PMCID: PMC7445825 DOI: 10.1093/synbio/ysz019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 06/17/2019] [Accepted: 06/18/2019] [Indexed: 12/22/2022] Open
Abstract
In vitro selection of ligand-responsive ribozymes can identify rare, functional sequences from large libraries. While powerful, key caveats of this approach include lengthy and demanding experimental workflows; unpredictable experimental outcomes and unknown functionality of enriched sequences in vivo. To address the first of these limitations, we developed Ligase-Assisted Selection for the Enrichment of Responsive Ribozymes (LigASERR). LigASERR is scalable, amenable to automation and requires less time to implement compared to alternative methods. To improve the predictability of experiments, we modeled the underlying selection process, predicting experimental outcomes based on sequence and population parameters. We applied this new methodology and model to the enrichment of a known, in vitro-selected sequence from a bespoke library. Prior to implementing selection, conditions were optimized and target sequence dynamics accurately predicted for the majority of the experiment. In addition to enriching the target sequence, we identified two new, theophylline-activated ribozymes. Notably, all three sequences yielded riboswitches functional in Escherichia coli, suggesting LigASERR and similar in vitro selection methods can be utilized for generating functional riboswitches in this organism.
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Affiliation(s)
- Matthew C Haines
- Department of Life Sciences, Imperial College London, London, UK.,Imperial College Centre for Synthetic Biology, Imperial College London, London, UK
| | - Marko Storch
- Department of Life Sciences, Imperial College London, London, UK.,Imperial College Centre for Synthetic Biology, Imperial College London, London, UK.,London BioFoundry, Imperial College Translation & Innovation Hub, London, UK
| | - Diego A Oyarzún
- School of Informatics, University of Edinburgh, Edinburgh, UK.,School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Guy-Bart Stan
- Imperial College Centre for Synthetic Biology, Imperial College London, London, UK.,Department of Bioengineering, Imperial College London, London, UK
| | - Geoff S Baldwin
- Department of Life Sciences, Imperial College London, London, UK.,Imperial College Centre for Synthetic Biology, Imperial College London, London, UK
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31
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Wong RS, Chen YY, Smolke CD. Regulation of T cell proliferation with drug-responsive microRNA switches. Nucleic Acids Res 2019; 46:1541-1552. [PMID: 29244152 PMCID: PMC5815133 DOI: 10.1093/nar/gkx1228] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/30/2017] [Indexed: 11/21/2022] Open
Abstract
As molecular and cellular therapies advance in the clinic, the role of genetic regulation is becoming increasingly important for controlling therapeutic potency and safety. The emerging field of mammalian synthetic biology provides promising tools for the construction of regulatory platforms that can intervene with endogenous pathways and control cell behavior. Recent work has highlighted the development of synthetic biological systems that integrate sensing of molecular signals to regulated therapeutic function in various disease settings. However, the toxicity and limited dosing of currently available molecular inducers have largely inhibited translation to clinical settings. In this work, we developed synthetic microRNA-based genetic systems that are controlled by the pharmaceutical drug leucovorin, which is readily available and safe for prolonged administration in clinical settings. We designed microRNA switches to target endogenous cytokine receptor subunits (IL-2Rβ and γc) that mediate various signaling pathways in T cells. We demonstrate the function of these control systems by effectively regulating T cell proliferation with the drug input. Each control system produced unique functional responses, and combinatorial targeting of multiple receptor subunits exhibited greater repression of cell growth. This work highlights the potential use of drug-responsive genetic control systems to improve the management and safety of cellular therapeutics.
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Affiliation(s)
- Remus S Wong
- Department of Bioengineering, 443 Via Ortega, MC 4245, Stanford University, Stanford, CA 94305, USA
| | - Yvonne Y Chen
- Department of Chemical and Biomolecular Engineering, 420 Westwood Plaza, Boelter Hall 5531, University of California-Los Angeles, Los Angeles, CA 90095, USA
| | - Christina D Smolke
- Department of Bioengineering, 443 Via Ortega, MC 4245, Stanford University, Stanford, CA 94305, USA.,Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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32
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Shi Q, Sutariya V, Varghese Gupta S, Bhatia D. GADD45α-targeted suicide gene therapy driven by synthetic CArG promoter E9NS sensitizes NSCLC cells to cisplatin, resveratrol, and radiation regardless of p53 status. Onco Targets Ther 2019; 12:3161-3170. [PMID: 31114253 PMCID: PMC6497884 DOI: 10.2147/ott.s192061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 03/12/2019] [Indexed: 12/12/2022] Open
Abstract
Background: GADD45α is a tumor suppressor protein often upregulated by environmental stresses and DNA-damage agents to cause growth arrest, apoptosis, tumor growth inhibition, and anti-angiogenesis. A novel suicide gene therapy vector pE9NS.G45α was engineered by cloning GADD45α opening reading frame downstream to the synthetic CArG promoter E9NS, which contains nine repeats of CArG element with modified core A/T sequence and functions as a molecular switch to drive the expression of GADD45α. The current study aims to determine the efficacy of this suicide gene therapy vector in combination with cisplatin, resveratrol, and radiation in NSCLC cell lines with various p53 statuses. Methods: Three NSCLC cell lines, H1299 (deleted p53), A549 (wild-type p53), and H23 (mutated p53), were examined in the present investigation to represent NSCLC with different p53 functions. MTT assay was conducted to select suitable doses of cisplatin, resveratrol, and radiation for gene therapy, and dual luciferase assay was performed to validate the activation of promoter E9NS. The efficacy of gene therapy combinations was evaluated by the amount of GADD45α expression, cell survival, and apoptosis. Results: All the combinations successfully activated promoter E9NS to elevate intracellular GADD45α protein levels and subsequently enhanced cell viability reduction and apoptosis induction regardless of p53 status. Conclusion: Our study demonstrates that GADD45α-targeted suicide gene therapy controlled by synthetic promoter E9NS sensitizes NSCLC cells to cisplatin, resveratrol, and radiation and is effective against NSCLC at least in vitro.
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Affiliation(s)
- Qiwen Shi
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
| | | | | | - Deepak Bhatia
- Bernard J. Dunn School of Pharmacy, Shenandoah University, Ashburn, VA, USA
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33
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Zhang J, Lan T, Lu Y. Molecular Engineering of Functional Nucleic Acid Nanomaterials toward In Vivo Applications. Adv Healthc Mater 2019; 8:e1801158. [PMID: 30725526 PMCID: PMC6426685 DOI: 10.1002/adhm.201801158] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 01/14/2019] [Indexed: 12/25/2022]
Abstract
Recent advances in nanotechnology and engineering have generated many nanomaterials with unique physical and chemical properties. Over the past decade, numerous nanomaterials are introduced into many research areas, such as sensors for environmental monitoring, food safety, point-of-care diagnostics, and as transducers for solar energy transfer. Meanwhile, functional nucleic acids (FNAs), including nucleic acid enzymes, aptamers, and aptazymes, have attracted major attention from the biomedical community due to their unique target recognition and catalytic properties. Benefiting from the recent progress of molecular engineering strategies, the physicochemical properties of nanomaterials are endowed by the target recognition and catalytic activity of FNAs in the presence of a target analyte, resulting in numerous smart nanoprobes for diverse applications including intracellular imaging, drug delivery, in vivo imaging, and tumor therapy. This progress report focuses on the recent advances in designing and engineering FNA-based nanomaterials, highlighting the functional outcomes toward in vivo applications. The challenges and opportunities for the future translation of FNA-based nanomaterials into clinical applications are also discussed.
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Affiliation(s)
- JingJing Zhang
- Department of Chemistry, University of Illinois at Urbana-Champaign, 601 S. Mathews Ave., Urbana, IL, 61801, USA
| | - Tian Lan
- GlucoSentient, Inc., 2100 S. Oak Street Suite 101, Champaign, IL, 61820, USA
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, 601 S. Mathews Ave., Urbana, IL, 61801, USA
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34
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Chong C, Low C. Synthetic antibody: Prospects in aquaculture biosecurity. FISH & SHELLFISH IMMUNOLOGY 2019; 86:361-367. [PMID: 30502461 DOI: 10.1016/j.fsi.2018.11.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/12/2018] [Accepted: 11/27/2018] [Indexed: 06/09/2023]
Abstract
The emerging technology of aptamers that is also known as synthetic antibodies is rivalling antibodies research in the recent years. The unique yet important features of aptamers are advancing antibodies in diverse applications, which include disease diagnosis, prophylactic and therapeutic. The versatility of aptamer has further extended its application to function as gene expression modulator, known as synthetic riboswitches. This report reviewed and discussed the applications of aptamers technology in the biosecurity of aquaculture, the promising developments in biosensor detection for disease diagnosis as well as prophylactic and therapeutic measurements. The application of aptamers technology in immunophenotyping study of aquatic animal is highlighted. Lastly, the future perspective of aptamers in the management of aquatic animal health is discussed, special emphasis on the potential application of aptamers as synthetic riboswitches to enhance host immunity, as well as the growth performance.
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Affiliation(s)
- ChouMin Chong
- Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia
| | - ChenFei Low
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, 43600, UKM Bangi, Selangor, Malaysia.
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35
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You M, Litke JL, Wu R, Jaffrey SR. Detection of Low-Abundance Metabolites in Live Cells Using an RNA Integrator. Cell Chem Biol 2019; 26:471-481.e3. [PMID: 30773480 DOI: 10.1016/j.chembiol.2019.01.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/05/2018] [Accepted: 01/10/2019] [Indexed: 01/05/2023]
Abstract
Genetically encoded biosensors are useful tools for detecting the presence and levels of diverse biomolecules in living cells. However, low-abundance targets are difficult to detect because they are often unable to bind and activate enough biosensors to detect using standard microscopic imaging approaches. Here we describe a type of RNA-based biosensor, an RNA integrator, which enables detection of low-abundance targets in vitro and in living cells. The RNA integrator is an RNA sequence comprising a ribozyme and an unfolded form of the fluorogenic aptamer Broccoli. Upon binding its target, the ribozyme undergoes cleavage and releases Broccoli, which subsequently folds and becomes fluorescent. Importantly, each target molecule can bind and induce cleavage of multiple copies of the integrator sensor, resulting in an amplified signal. We show that this approach can be generalized to numerous different ribozyme types for the detection of various small molecules.
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Affiliation(s)
- Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA; Department of Pharmacology, Weill Medical College, Weill Cornell Medicine, New York, NY 10065, USA.
| | - Jacob L Litke
- Department of Pharmacology, Weill Medical College, Weill Cornell Medicine, New York, NY 10065, USA
| | - Rigumula Wu
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Medical College, Weill Cornell Medicine, New York, NY 10065, USA.
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36
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Galizi R, Jaramillo A. Engineering CRISPR guide RNA riboswitches for in vivo applications. Curr Opin Biotechnol 2019; 55:103-113. [PMID: 30265865 DOI: 10.1016/j.copbio.2018.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/13/2018] [Accepted: 08/16/2018] [Indexed: 02/07/2023]
Abstract
CRISPR-based genome editing provides a simple and scalable toolbox for a variety of therapeutic and biotechnology applications. Whilst the fundamental properties of CRISPR proved easily transferable from the native prokaryotic hosts to eukaryotic and multicellular organisms, the tight control of the CRISPR-editing activity remains a major challenge. Here we summarise recent developments of CRISPR and riboswitch technologies and recommend novel functionalised synthetic-gRNA (sgRNA) designs to achieve inducible and spatiotemporal regulation of CRISPR-based genetic editors in response to cellular or extracellular stimuli. We believe that future advances of these tools will have major implications for both basic and applied research, spanning from fundamental genetic studies and synthetic biology to genetic editing and gene therapy.
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Affiliation(s)
- Roberto Galizi
- Department of Life Sciences, Imperial College London, London, United Kingdom.
| | - Alfonso Jaramillo
- Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, CV4 7AL Coventry, United Kingdom; ISSB, CNRS, Univ Evry, CEA, Université Paris-Saclay, 91025 Evry, France; Institute for Integrative Systems Biology (I2SysBio), University of Valencia-CSIC, 46980 Paterna, Spain.
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37
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Chen H, Li Y, Du C, Li Y, Zhao J, Zheng X, Mao Q, Xia H. Aptazyme-mediated direct modulation of post-transcriptional sgRNA level for conditional genome editing and gene expression. J Biotechnol 2018; 288:23-29. [PMID: 30391232 DOI: 10.1016/j.jbiotec.2018.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 10/15/2018] [Accepted: 10/30/2018] [Indexed: 12/26/2022]
Abstract
RNA-guided endonuclease Cas9 derived from microbial CRISPR-Cas adaptive immune systems is a powerful tool for genome editing, which has been widely used in eukaryotic systems, prokaryotic systems, and plants. However, the off-target effects caused by Cas9/sgRNA remain a major concern. Currently, the efforts to reduce the off-target effects mainly focus on improving the targeting specificity of sgRNA/Cas9, regulating the activity of the Cas9 protein or the sgRNA, and controlling the time window of their expression. In this study, a novel system was established to regulate the post-transcriptional sgRNA level by small molecule-controlled aptazyme. This system was shown to reduce the off-target effects caused by Cas9/sgRNA, while enabling precise temporal control over gene editing and regulatory activity. This new system could provide a potentially safer and more powerful tool for genome editing and therapeutic application.
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Affiliation(s)
- Hao Chen
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, PR China
| | - Yanqing Li
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, PR China
| | - Chunhua Du
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, PR China
| | - Yan Li
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, PR China
| | - Junli Zhao
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, PR China
| | - Xiaojing Zheng
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, PR China
| | - Qinwen Mao
- Department of Pathology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Ward 3-140, Chicago, IL 60611, USA
| | - Haibin Xia
- Laboratory of Gene Therapy, Department of Biochemistry, College of Life Sciences, Shaanxi Normal University, 199 South Chang'an Road, Xi'an, 710062, Shaanxi, PR China.
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38
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Sinumvayo JP, Zhao C, Tuyishime P. Recent advances and future trends of riboswitches: attractive regulatory tools. World J Microbiol Biotechnol 2018; 34:171. [PMID: 30413889 DOI: 10.1007/s11274-018-2554-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 11/02/2018] [Indexed: 01/06/2023]
Abstract
Bacterial genomes contain a huge amount of different genes. These genes are spatiotemporally expressed to accomplish some required functions within the organism. Inside the cell, any step of gene expression may be modulated at four possible places such as transcription initiation, translation regulation, mRNA stability and protein stability. To achieve this, there is a necessity of strong regulators either natural or synthetic which can fine-tune gene expression regarding the required function. In recent years, riboswitches as metabolite responsive control elements residing in the untranslated regions of certain messenger RNAs, have been known to control gene expression at transcription or translation level. Importantly, these control elements do not prescribe the involvement of protein factors for metabolite binding. However, they own their particular properties to sense intramolecular metabolites (ligands). Herein, we highlighted current important bacterial riboswitches, their applications to support genetic control, ligand-binding domain mechanisms and current progress in synthetic riboswitches.
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Affiliation(s)
- Jean Paul Sinumvayo
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. .,University of Chinese Academy of Sciences, Beijing, China.
| | - Chunhua Zhao
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Philibert Tuyishime
- University of Chinese Academy of Sciences, Beijing, China.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
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Lin MW, Tseng YW, Shen CC, Hsu MN, Hwu JR, Chang CW, Yeh CJ, Chou MY, Wu JC, Hu YC. Synthetic switch-based baculovirus for transgene expression control and selective killing of hepatocellular carcinoma cells. Nucleic Acids Res 2018; 46:e93. [PMID: 29905834 PMCID: PMC6125686 DOI: 10.1093/nar/gky447] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/04/2018] [Accepted: 05/31/2018] [Indexed: 12/13/2022] Open
Abstract
Baculovirus (BV) holds promise as a vector for anticancer gene delivery to combat the most common liver cancer-hepatocellular carcinoma (HCC). However, in vivo BV administration inevitably results in BV entry into non-HCC normal cells, leaky anticancer gene expression and possible toxicity. To improve the safety, we employed synthetic biology to engineer BV for transgene expression regulation. We first uncovered that miR-196a and miR-126 are exclusively expressed in HCC and normal cells, respectively, which allowed us to engineer a sensor based on distinct miRNA expression signature. We next assembled a synthetic switch by coupling the miRNA sensor and RNA binding protein L7Ae for translational repression, and incorporated the entire device into a single BV. The recombinant BV efficiently entered HCC and normal cells and enabled cis-acting transgene expression control, by turning OFF transgene expression in normal cells while switching ON transgene expression in HCC cells. Using pro-apoptotic hBax as the transgene, the switch-based BV selectively killed HCC cells in separate culture and mixed culture of HCC and normal cells. These data demonstrate the potential of synthetic switch-based BV to distinguish HCC and non-HCC normal cells for selective transgene expression control and killing of HCC cells.
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Affiliation(s)
- Mei-Wei Lin
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Yen-Wen Tseng
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Chih-Che Shen
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Mu-Nung Hsu
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Jih-Ru Hwu
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu, Taiwan
| | - Chin-Wei Chang
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Chung-Ju Yeh
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Min-Yuan Chou
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Jaw-Ching Wu
- Medical Research Department, Taipei Veterans General Hospital, Taipei Taiwan
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Chen Hu
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu, Taiwan
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Whitford CM, Dymek S, Kerkhoff D, März C, Schmidt O, Edich M, Droste J, Pucker B, Rückert C, Kalinowski J. Auxotrophy to Xeno-DNA: an exploration of combinatorial mechanisms for a high-fidelity biosafety system for synthetic biology applications. J Biol Eng 2018; 12:13. [PMID: 30123321 PMCID: PMC6090650 DOI: 10.1186/s13036-018-0105-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 06/25/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Biosafety is a key aspect in the international Genetically Engineered Machine (iGEM) competition, which offers student teams an amazing opportunity to pursue their own research projects in the field of Synthetic Biology. iGEM projects often involve the creation of genetically engineered bacterial strains. To minimize the risks associated with bacterial release, a variety of biosafety systems were constructed, either to prevent survival of bacteria outside the lab or to hinder horizontal or vertical gene transfer. MAIN BODY Physical containment methods such as bioreactors or microencapsulation are considered the first safety level. Additionally, various systems involving auxotrophies for both natural and synthetic compounds have been utilized by iGEM teams in recent years. Combinatorial systems comprising multiple auxotrophies have been shown to reduced escape frequencies below the detection limit. Furthermore, a number of natural toxin-antitoxin systems can be deployed to kill cells under certain conditions. Additionally, parts of naturally occurring toxin-antitoxin systems can be used for the construction of 'kill switches' controlled by synthetic regulatory modules, allowing control of cell survival. Kill switches prevent cell survival but do not completely degrade nucleic acids. To avoid horizontal gene transfer, multiple mechanisms to cleave nucleic acids can be employed, resulting in 'self-destruction' of cells. Changes in light or temperature conditions are powerful regulators of gene expression and could serve as triggers for kill switches or self-destruction systems. Xenobiology-based containment uses applications of Xeno-DNA, recoded codons and non-canonical amino acids to nullify the genetic information of constructed cells for wild type organisms. A 'minimal genome' approach brings the opportunity to reduce the genome of a cell to only genes necessary for survival under lab conditions. Such cells are unlikely to survive in the natural environment and are thus considered safe hosts. If suitable for the desired application, a shift to cell-free systems based on Xeno-DNA may represent the ultimate biosafety system. CONCLUSION Here we describe different containment approaches in synthetic biology, ranging from auxotrophies to minimal genomes, which can be combined to significantly improve reliability. Since the iGEM competition greatly increases the number of people involved in synthetic biology, we will focus especially on biosafety systems developed and applied in the context of the iGEM competition.
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Affiliation(s)
| | - Saskia Dymek
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
| | - Denise Kerkhoff
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
| | - Camilla März
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
| | - Olga Schmidt
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
| | - Maximilian Edich
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
| | - Julian Droste
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
- Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Boas Pucker
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
- Faculty of Biology, Bielefeld University, Bielefeld, Germany
- Present address: Evolution and Diversity, Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Christian Rückert
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
- Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Jörn Kalinowski
- Center for Biotechnology, Bielefeld University, 33615 Bielefeld, Germany
- Faculty of Biology, Bielefeld University, Bielefeld, Germany
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Ungerechts G, Engeland CE, Buchholz CJ, Eberle J, Fechner H, Geletneky K, Holm PS, Kreppel F, Kühnel F, Lang KS, Leber MF, Marchini A, Moehler M, Mühlebach MD, Rommelaere J, Springfeld C, Lauer UM, Nettelbeck DM. Virotherapy Research in Germany: From Engineering to Translation. Hum Gene Ther 2018; 28:800-819. [PMID: 28870120 DOI: 10.1089/hum.2017.138] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Virotherapy is a unique modality for the treatment of cancer with oncolytic viruses (OVs) that selectively infect and lyse tumor cells, spread within tumors, and activate anti-tumor immunity. Various viruses are being developed as OVs preclinically and clinically, several of them engineered to encode therapeutic proteins for tumor-targeted gene therapy. Scientists and clinicians in German academia have made significant contributions to OV research and development, which are highlighted in this review paper. Innovative strategies for "shielding," entry or postentry targeting, and "arming" of OVs have been established, focusing on adenovirus, measles virus, parvovirus, and vaccinia virus platforms. Thereby, new-generation virotherapeutics have been derived. Moreover, immunotherapeutic properties of OVs and combination therapies with pharmacotherapy, radiotherapy, and especially immunotherapy have been investigated and optimized. German investigators are increasingly assessing their OV innovations in investigator-initiated and sponsored clinical trials. As a prototype, parvovirus has been tested as an OV from preclinical proof-of-concept up to first-in-human clinical studies. The approval of the first OV in the Western world, T-VEC (Imlygic), has further spurred the involvement of investigators in Germany in international multicenter studies. With the encouraging developments in funding, commercialization, and regulatory procedures, more German engineering will be translated into OV clinical trials in the near future.
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Affiliation(s)
- Guy Ungerechts
- 1 Department of Medical Oncology, National Center for Tumor Diseases and Heidelberg University Hospital , Heidelberg, Germany .,2 Department of Translational Oncology, National Center for Tumor Diseases and German Cancer Research Center (DKFZ), Heidelberg, Germany .,3 Centre for Innovative Cancer Research, Ottawa Hospital Research Institute , Ottawa, Ontario, Canada
| | - Christine E Engeland
- 1 Department of Medical Oncology, National Center for Tumor Diseases and Heidelberg University Hospital , Heidelberg, Germany .,2 Department of Translational Oncology, National Center for Tumor Diseases and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christian J Buchholz
- 4 Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut , Langen, Germany .,5 German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), partner site Heidelberg, Germany
| | - Jürgen Eberle
- 6 Charité -Universitätsmedizin Berlin, Department of Dermatology, Skin Cancer Centre Charité , Berlin, Germany
| | - Henry Fechner
- 7 Technische Universität Berlin, Institute of Biotechnology , Department of Applied Biochemistry, Berlin, Germany
| | - Karsten Geletneky
- 8 Department of Neurosurgery, Klinikum Darmstadt , Darmstadt, Germany
| | - Per Sonne Holm
- 9 Department of Urology, Klinikum rechts der Isar, Technical University Munich , Munich, Germany
| | - Florian Kreppel
- 10 Chair of Biochemistry and Molecular Medicine, Center for Biomedical Research and Education (ZBAF), Faculty of Health, University Witten/Herdecke (UW/H), Witten, Germany
| | - Florian Kühnel
- 11 Department of Gastroenterology, Hepatology, and Endocrinology, Hannover Medical School (MHH), Hannover, Germany
| | - Karl Sebastian Lang
- 12 Institute of Immunology, Medical Faculty, University of Duisburg-Essen , Essen, Germany
| | - Mathias F Leber
- 1 Department of Medical Oncology, National Center for Tumor Diseases and Heidelberg University Hospital , Heidelberg, Germany .,2 Department of Translational Oncology, National Center for Tumor Diseases and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Antonio Marchini
- 13 Department of Tumor Virology, Infection, Inflammation and Cancer Program, German Cancer Research Center (DKFZ), Heidelberg, Germany .,14 Laboratory of Oncolytic Virus Immuno-Therapeutics (LOVIT), Luxembourg Institute of Health (LIH), Strassen, Luxembourg
| | - Markus Moehler
- 15 University Medical Center Mainz , I. Dept. of Internal Medicine, Mainz, Germany
| | - Michael D Mühlebach
- 16 Product Testing of Immunological Veterinary Medicinal Products, Paul-Ehrlich-Institut , Langen, Germany
| | - Jean Rommelaere
- 13 Department of Tumor Virology, Infection, Inflammation and Cancer Program, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Christoph Springfeld
- 1 Department of Medical Oncology, National Center for Tumor Diseases and Heidelberg University Hospital , Heidelberg, Germany
| | - Ulrich M Lauer
- 17 Department of Clinical Tumor Biology, Medical University Hospital , Tübingen, Germany .,18 German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), partner site Tübingen, Germany
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Patel S, Panchasara H, Braddick D, Gohil N, Singh V. Synthetic small RNAs: Current status, challenges, and opportunities. J Cell Biochem 2018; 119:9619-9639. [DOI: 10.1002/jcb.27252] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/20/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Shreya Patel
- Department of Microbiology, Synthetic Biology Laboratory School of Biological Sciences and Biotechnology, Institute of Advanced Research, Koba Institutional Area Gandhinagar India
| | - Happy Panchasara
- Department of Microbiology, Synthetic Biology Laboratory School of Biological Sciences and Biotechnology, Institute of Advanced Research, Koba Institutional Area Gandhinagar India
| | | | - Nisarg Gohil
- Department of Microbiology, Synthetic Biology Laboratory School of Biological Sciences and Biotechnology, Institute of Advanced Research, Koba Institutional Area Gandhinagar India
| | - Vijai Singh
- Department of Microbiology, Synthetic Biology Laboratory School of Biological Sciences and Biotechnology, Institute of Advanced Research, Koba Institutional Area Gandhinagar India
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43
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Cheng T, Song Y, Zhang Y, Zhang C, Yin J, Chi Y, Zhou D. A novel oncolytic adenovirus based on simian adenovirus serotype 24. Oncotarget 2018; 8:26871-26885. [PMID: 28460470 PMCID: PMC5432303 DOI: 10.18632/oncotarget.15845] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/20/2017] [Indexed: 12/26/2022] Open
Abstract
Among the oncolytic virotherapy, an emerging treatment for tumor, adenoviruses are widely used at present in preclinical and clinical trials. Traditionally, oncolytic adenoviruses were developed based on the human adenovirus serotype 5 (AdHu5). However, AdHu5 has the drawbacks of preexisting anti-AdHu5 immunity in most populations, and extensive sequestration of Adhu5 by the liver through hexon, blood coagulation factor X (FX), and FX receptor interactions. To tackle these problems, we explored a novel oncolytic adenovirus AdC7-SP/E1A-ΔE3 for cancer treatment. AdC7-SP/E1A-ΔE3 was constructed by replacing the E1A promoter with tumor specific promoter survivin promoter and deleting E3 region using direct cloning methods based on simian adenovirus serotype 24 (namely AdC7). We showed that AdC7-SP/E1A-ΔE3 significantly killed tumor cell lines NCI-H508 and Huh7, and inhibited tumor growth in both NCI-H508 and Huh7 xenograft tumor models. Importantly, AdC7-SP/E1A-ΔE3 exhibited the antitumor efficacy via systemic administration. Mechanistically, infected cells were killed by AdC7-SP/E1A-ΔE3 via the p53-independent mitochondrial apoptosis pathway in which phosphorylation of BAD markedly declined and the expresses of Bik significantly went up. Therefore, AdC7-SP/E1A-ΔE3 is a promising candidate for liver and colon tumor treatment.
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Affiliation(s)
- Tao Cheng
- Vaccine Research Center, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Science, Shanghai 200031, China
| | - Yufeng Song
- Vaccine Research Center, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Science, Shanghai 200031, China
| | - Yan Zhang
- Vaccine Research Center, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Science, Shanghai 200031, China
| | - Chao Zhang
- Vaccine Research Center, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Science, Shanghai 200031, China
| | - Jieyun Yin
- Vaccine Research Center, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Science, Shanghai 200031, China
| | - Yudan Chi
- Vaccine Research Center, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Science, Shanghai 200031, China
| | - Dongming Zhou
- Vaccine Research Center, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Science, Shanghai 200031, China
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Mou H, Zhong G, Gardner MR, Wang H, Wang YW, Cheng D, Farzan M. Conditional Regulation of Gene Expression by Ligand-Induced Occlusion of a MicroRNA Target Sequence. Mol Ther 2018; 26:1277-1286. [PMID: 29567311 PMCID: PMC5993935 DOI: 10.1016/j.ymthe.2018.02.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 11/03/2022] Open
Abstract
RNA switches that modulate gene expression with small molecules have a number of scientific and clinical applications. Here, we describe a novel class of small regulatory on switches based on the ability of a ligand-bound aptamer to promote stem formation between a microRNA target sequence (miR-T) and a complementary competing strand. Two on switch architectures employing this basic concept were evaluated, differing in the location of a tetracycline aptamer and the region of a miR-21 target sequence (miR-21-T) masked by its competing strand. Further optimizations of miR-21-T and its competing strand resulted in tetracycline-regulated on switches that induced luciferase expression by 19-fold in HeLa cells. A similar switch design based on miR-122-T afforded 7-fold regulation when placed in tandem, indicating that this approach can be extended to additional miR-T. Optimized on switches introduced into adeno-associated virus (AAV) vectors afforded 10-fold regulation of two antiviral proteins in AAV-transduced cells. Our data demonstrate that small-molecule-induced occlusion of a miR-T can be used to conditionally regulate gene expression in mammalian cells and suggest that regulatory switches built on this principle can be used to dose expression of an AAV transgene.
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Affiliation(s)
- Huihui Mou
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Guocai Zhong
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA.
| | - Matthew R Gardner
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Haimin Wang
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yi-Wen Wang
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Dechun Cheng
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Parasitology, Harbin Medical University, Harbin 150081, China
| | - Michael Farzan
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA.
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Speck T, Heidbuechel JPW, Veinalde R, Jaeger D, von Kalle C, Ball CR, Ungerechts G, Engeland CE. Targeted BiTE Expression by an Oncolytic Vector Augments Therapeutic Efficacy Against Solid Tumors. Clin Cancer Res 2018; 24:2128-2137. [PMID: 29437789 DOI: 10.1158/1078-0432.ccr-17-2651] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 01/02/2018] [Accepted: 01/31/2018] [Indexed: 02/04/2023]
Abstract
Purpose: Immunotherapy with bispecific T-cell engagers has achieved striking success against hematologic malignancies, but efficacy against solid tumors has been limited. We hypothesized that oncolytic measles viruses encoding bispecific T-cell engagers (MV-BiTEs) represent a safe and effective treatment against solid tumors through local BiTE expression, direct tumor cell lysis and in situ tumor vaccination.Experimental Design: To test this hypothesis, we generated MV-BiTEs from the Edmonston B vaccine strain to target two model antigens. Replicative and oncolytic potential were assessed by infection and cell viability assays, respectively. Functionality of virus-derived BiTEs was tested in vitro by complementary binding and cytotoxicity assays. In vivo efficacy of MV-BiTE was investigated using both syngeneic and xenograft mouse models of solid cancers.Results: We verified secretion of functional BiTE antibodies by MV-BiTE-infected cells. Further, we demonstrated therapeutic efficacy of MV-BiTE against established tumors in fully immunocompetent mice. MV-BiTE efficacy was associated with increased intratumoral T-cell infiltration and induction of protective antitumor immunity. In addition, we showed therapeutic efficacy of MV-BiTE in xenograft models of patient-derived primary colorectal carcinoma spheroids with transfer of peripheral blood mononuclear cells.Conclusions: MV-BiTE treatment was effective in two distinct models of solid tumors without signs of toxicity. This provides strong evidence for therapeutic benefits of tumor-targeted BiTE expression by oncolytic MV. Thus, this study represents proof of concept for an effective strategy to treat solid tumors with BiTEs. Clin Cancer Res; 24(9); 2128-37. ©2018 AACR.
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Affiliation(s)
- Tobias Speck
- Department of Translational Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany.,Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Johannes P W Heidbuechel
- Department of Translational Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany.,Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Rūta Veinalde
- Department of Translational Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany
| | - Dirk Jaeger
- Department of Medical Oncology, University Hospital Heidelberg and National Center for Tumor Diseases (NCT), Heidelberg, Germany
| | - Christof von Kalle
- Department of Translational Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany
| | - Claudia R Ball
- Department of Translational Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany
| | - Guy Ungerechts
- Department of Translational Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany.,Department of Medical Oncology, University Hospital Heidelberg and National Center for Tumor Diseases (NCT), Heidelberg, Germany.,Ottawa Hospital Research Institute, Centre for Innovative Cancer Research, Ottawa, Ontario, Canada
| | - Christine E Engeland
- Department of Translational Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany. .,Department of Medical Oncology, University Hospital Heidelberg and National Center for Tumor Diseases (NCT), Heidelberg, Germany
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Rossetti M, Porchetta A. Allosterically regulated DNA-based switches: From design to bioanalytical applications. Anal Chim Acta 2018; 1012:30-41. [PMID: 29475471 DOI: 10.1016/j.aca.2017.12.046] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 12/10/2017] [Accepted: 12/28/2017] [Indexed: 02/07/2023]
Abstract
DNA-based switches are structure-switching biomolecules widely employed in different bioanalytical applications. Of particular interest are DNA-based switches whose activity is regulated through the use of allostery. Allostery is a naturally occurring mechanism in which ligand binding induces the modulation and fine control of a connected biomolecule function as a consequence of changes in concentration of the effector. Through this general mechanism, many different allosteric DNA-based switches able to respond in a highly controlled way at the presence of a specific molecular effector have been engineered. Here, we discuss how to design allosterically regulated DNA-based switches and their applications in the field of molecular sensing, diagnostic and drug release.
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Affiliation(s)
- Marianna Rossetti
- Chemistry Department, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Alessandro Porchetta
- Chemistry Department, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy.
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47
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Studying Parasite Gene Function and Interaction Through Ribozymes and Riboswitches Design Mechanism. Synth Biol (Oxf) 2018. [DOI: 10.1007/978-981-10-8693-9_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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48
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Wurmthaler LA, Klauser B, Hartig JS. Highly motif- and organism-dependent effects of naturally occurring hammerhead ribozyme sequences on gene expression. RNA Biol 2017; 15:231-241. [PMID: 29106331 DOI: 10.1080/15476286.2017.1397870] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Recent bioinformatics studies have demonstrated a wide-spread occurrence of the hammerhead ribozyme (HHR) and similar small endonucleolytic RNA motifs in all domains of life. It is becoming increasingly evident that such ribozyme motifs participate in important genetic processes in diverse organisms. Although the HHR motif has been studied for more than three decades, only little is known about the consequences of ribozyme activity on gene expression. In the present study we analysed eight different naturally occurring HHR sequences in diverse genetic and organismal contexts. We investigated the influence of active ribozymes incorporated into mRNAs in mammalian, yeast and bacterial expression systems. The experiments show an unexpectedly high degree of organism-specific variability of ribozyme-mediated effects on gene expression. The presented findings demonstrate that ribozyme cleavage profoundly affect gene expression. However, the extent of this effect varies and depends strongly on the respective genetic context. The fast-cleaving type 3 HHRs [CChMVd(-) and sLTSV(-)] generally tended to cause the strongest effects on intracellular gene expression. The presented results are important in order to address potential functions of naturally occurring ribozymes in RNA processing and post-transcriptional regulation of gene expression. Additionally, our results are of interest for biotechnology and synthetic biology approaches that aim at the utilisation of self-cleaving ribozymes as widely applicable tools for controlling genetic processes.
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Affiliation(s)
- Lena A Wurmthaler
- a Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB) , University of Konstanz , Konstanz , Germany
| | - Benedikt Klauser
- a Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB) , University of Konstanz , Konstanz , Germany
| | - Jörg S Hartig
- a Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB) , University of Konstanz , Konstanz , Germany
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49
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Kim CM, Smolke CD. Biomedical applications of RNA-based devices. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2017; 4:106-115. [DOI: 10.1016/j.cobme.2017.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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50
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Ausländer S, Fussenegger M. Synthetic RNA-based switches for mammalian gene expression control. Curr Opin Biotechnol 2017; 48:54-60. [DOI: 10.1016/j.copbio.2017.03.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/10/2017] [Indexed: 01/25/2023]
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