1
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Chew YH, Marucci L. Mechanistic Model-Driven Biodesign in Mammalian Synthetic Biology. Methods Mol Biol 2024; 2774:71-84. [PMID: 38441759 DOI: 10.1007/978-1-0716-3718-0_6] [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] [Indexed: 03/07/2024]
Abstract
Mathematical modeling plays a vital role in mammalian synthetic biology by providing a framework to design and optimize design circuits and engineered bioprocesses, predict their behavior, and guide experimental design. Here, we review recent models used in the literature, considering mathematical frameworks at the molecular, cellular, and system levels. We report key challenges in the field and discuss opportunities for genome-scale models, machine learning, and cybergenetics to expand the capabilities of model-driven mammalian cell biodesign.
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Affiliation(s)
- Yin Hoon Chew
- School of Mathematics, University of Birmingham, Birmingham, UK
| | - Lucia Marucci
- Department of Engineering Mathematics, University of Bristol, Bristol, UK.
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK.
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2
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Khalifah BA, Alghamdi SA, Alhasan AH. Unleashing the potential of catalytic RNAs to combat mis-spliced transcripts. Front Bioeng Biotechnol 2023; 11:1244377. [PMID: 38047291 PMCID: PMC10690607 DOI: 10.3389/fbioe.2023.1244377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/23/2023] [Indexed: 12/05/2023] Open
Abstract
Human transcriptome can undergo RNA mis-splicing due to spliceopathies contributing to the increasing number of genetic diseases including muscular dystrophy (MD), Alzheimer disease (AD), Huntington disease (HD), myelodysplastic syndromes (MDS). Intron retention (IR) is a major inducer of spliceopathies where two or more introns remain in the final mature mRNA and account for many intronic expansion diseases. Potential removal of such introns for therapeutic purposes can be feasible when utilizing bioinformatics, catalytic RNAs, and nano-drug delivery systems. Overcoming delivery challenges of catalytic RNAs was discussed in this review as a future perspective highlighting the significance of utilizing synthetic biology in addition to high throughput deep sequencing and computational approaches for the treatment of mis-spliced transcripts.
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Affiliation(s)
- Bashayer A. Khalifah
- Institute for Bioengineering, Health Sector, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
- Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - Ali H. Alhasan
- Institute for Bioengineering, Health Sector, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
- College of Science and General Studies, Alfaisal University, Riyadh, Saudi Arabia
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3
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Dykstra PB, Rando TA, Smolke CD. Modulating myoblast differentiation with RNA-based controllers. PLoS One 2022; 17:e0275298. [PMID: 36166456 PMCID: PMC9514614 DOI: 10.1371/journal.pone.0275298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 09/13/2022] [Indexed: 02/03/2023] Open
Abstract
Tunable genetic controllers play a critical role in the engineering of biological systems that respond to environmental and cellular signals. RNA devices, a class of engineered RNA-based controllers, enable tunable gene expression control of target genes in response to molecular effectors. RNA devices have been demonstrated in a number of systems showing proof-of-concept of applying ligand-responsive control over therapeutic activities, including regulation of cell fate decisions such as T cell proliferation and apoptosis. Here, we describe the application of a theophylline-responsive RNA device in a muscle progenitor cell system to control myogenic differentiation. Ribozyme-based RNA switches responsive to theophylline control fluorescent reporter expression in C2C12 myoblasts in a ligand dependent manner. HRAS and JAK1, both anti-differentiation proteins, were incorporated into RNA devices. Finally, we demonstrate that the regulation of HRAS expression via theophylline-responsive RNA devices results in the modulation of myoblast differentiation in a theophylline-dependent manner. Our work highlights the potential for RNA devices to exert drug-responsive, tunable control over cell fate decisions with applications in stem cell therapy and basic stem cell biology research.
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Affiliation(s)
- Peter B. Dykstra
- Department of Bioengineering, Stanford University, Stanford, CA, United States of America
| | - Thomas A. Rando
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, United States of America
- Paul F. Glenn Center for the Biology of Aging, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Christina D. Smolke
- Department of Bioengineering, Stanford University, Stanford, CA, United States of America
- Chan Zuckerberg Biohub, San Francisco, CA, United States of America
- * E-mail:
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4
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Crone MA, MacDonald JT, Freemont PS, Siciliano V. gDesigner: computational design of synthetic gRNAs for Cas12a-based transcriptional repression in mammalian cells. NPJ Syst Biol Appl 2022; 8:34. [PMID: 36114193 PMCID: PMC9481559 DOI: 10.1038/s41540-022-00241-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/28/2022] [Indexed: 11/09/2022] Open
Abstract
Synthetic networks require complex intertwined genetic regulation often relying on transcriptional activation or repression of target genes. CRISPRi-based transcription factors facilitate the programmable modulation of endogenous or synthetic promoter activity and the process can be optimised by using software to select appropriate gRNAs and limit non-specific gene modulation. Here, we develop a computational software pipeline, gDesigner, that enables the automated selection of orthogonal gRNAs with minimized off-target effects and promoter crosstalk. We next engineered a Lachnospiraceae bacterium Cas12a (dLbCas12a)-based repression system that downregulates target gene expression by means of steric hindrance of the cognate promoter. Finally, we generated a library of orthogonal synthetic dCas12a-repressed promoters and experimentally demonstrated it in HEK293FT, U2OS and H1299 cells lines. Our system expands the toolkit of mammalian synthetic promoters with a new complementary and orthogonal CRISPRi-based system, ultimately enabling the design of synthetic promoter libraries for multiplex gene perturbation that facilitate the understanding of complex cellular phenotypes.
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Affiliation(s)
- Michael A Crone
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
- UK Dementia Research Institute Centre for Care Research and Technology, Imperial College London, London, United Kingdom
- London Biofoundry, Imperial College Translation and Innovation Hub, White City Campus, 84 Wood Lane, London, United Kingdom
| | - James T MacDonald
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom.
| | - Paul S Freemont
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom.
- UK Dementia Research Institute Centre for Care Research and Technology, Imperial College London, London, United Kingdom.
- London Biofoundry, Imperial College Translation and Innovation Hub, White City Campus, 84 Wood Lane, London, United Kingdom.
| | - Velia Siciliano
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom.
- Istituto Italiano di Tecnologia IIT, Department of Synthetic and Systems Biology for Biomedicine, Genoa, Italy.
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5
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Finke M, Brecht D, Stifel J, Gense K, Gamerdinger M, Hartig JS. Efficient splicing-based RNA regulators for tetracycline-inducible gene expression in human cell culture and C. elegans. Nucleic Acids Res 2021; 49:e71. [PMID: 33893804 PMCID: PMC8266659 DOI: 10.1093/nar/gkab233] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/17/2021] [Accepted: 04/23/2021] [Indexed: 01/07/2023] Open
Abstract
Synthetic riboswitches gain increasing interest for controlling transgene expression in diverse applications ranging from synthetic biology, functional genomics, and pharmaceutical target validation to potential therapeutic approaches. However, existing systems often lack the pharmaceutically suited ligands and dynamic responses needed for advanced applications. Here we present a series of synthetic riboswitches for controlling gene expression through the regulation of alternative splicing. Placing the 5′-splice site into a stem structure of a tetracycline-sensing aptamer allows us to regulate the accessibility of the splice site. In the presence of tetracycline, an exon with a premature termination codon is skipped and gene expression can occur, whereas in its absence the exon is included into the coding sequence, repressing functional protein expression. We were able to identify RNA switches controlling protein expression in human cells with high dynamic ranges and different levels of protein expression. We present minimalistic versions of this system that circumvent the need to insert an additional exon. Further, we demonstrate the robustness of our approach by transferring the devices into the important research model organism Caenorhabditis elegans, where high levels of functional protein with very low background expression could be achieved.
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Affiliation(s)
- Monika Finke
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Dominik Brecht
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Julia Stifel
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Karina Gense
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.,Department of Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Martin Gamerdinger
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.,Department of Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Jörg S Hartig
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
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6
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Moore WM, Milshteyn D, Tsai YT, Budin I. Engineering the bilayer: Emerging genetic tool kits for mechanistic lipid biology. Curr Opin Chem Biol 2021; 65:66-73. [PMID: 34218059 DOI: 10.1016/j.cbpa.2021.05.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 11/19/2022]
Abstract
The structural diversity of lipids underpins the biophysical properties of cellular membranes, which vary across all scales of biological organization. Because lipid composition results from complex metabolic and transport pathways, its experimental control has been a major goal of mechanistic membrane biology. Here, we argue that in the wake of synthetic biology, similar metabolic engineering strategies can be applied to control the composition, physicochemical properties, and function of cell membranes. In one emerging area, titratable expression platforms allow for specific and genome-wide alterations in lipid biosynthetic genes, providing analog control over lipidome stoichiometry in membranes. Simultaneously, heterologous expression of biosynthetic genes and pathways has allowed for gain-of-function experiments with diverse lipids in non-native systems. Finally, we highlight future directions for tool development, including recently discovered lipid transport pathways to intracellular lipid pools. Further tool development providing synthetic control of membrane properties can allow biologists to untangle membrane lipid structure-associated functions.
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Affiliation(s)
- William M Moore
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Daniel Milshteyn
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Yi-Ting Tsai
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Itay Budin
- Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
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7
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Khakhar A, Voytas DF. RNA Viral Vectors for Accelerating Plant Synthetic Biology. FRONTIERS IN PLANT SCIENCE 2021; 12:668580. [PMID: 34249040 PMCID: PMC8261061 DOI: 10.3389/fpls.2021.668580] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/19/2021] [Indexed: 05/03/2023]
Abstract
The tools of synthetic biology have enormous potential to help us uncover the fundamental mechanisms controlling development and metabolism in plants. However, their effective utilization typically requires transgenesis, which is plagued by long timescales and high costs. In this review we explore how transgenesis can be minimized by delivering foreign genetic material to plants with systemically mobile and persistent vectors based on RNA viruses. We examine the progress that has been made thus far and highlight the hurdles that need to be overcome and some potential strategies to do so. We conclude with a discussion of biocontainment mechanisms to ensure these vectors can be used safely as well as how these vectors might expand the accessibility of plant synthetic biology techniques. RNA vectors stand poised to revolutionize plant synthetic biology by making genetic manipulation of plants cheaper and easier to deploy, as well as by accelerating experimental timescales from years to weeks.
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Affiliation(s)
- Arjun Khakhar
- Department of Genetics, Cell Biology and Development, University of Minnesota, St. Paul, MN, United States
| | - Daniel F. Voytas
- Department of Genetics, Cell Biology and Development, University of Minnesota, St. Paul, MN, United States
- Center for Precision Plant Genomics, University of Minnesota, St. Paul, MN, United States
- Center for Genome Engineering, University of Minnesota, St. Paul, MN, United States
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8
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Shakiba N, Jones RD, Weiss R, Del Vecchio D. Context-aware synthetic biology by controller design: Engineering the mammalian cell. Cell Syst 2021; 12:561-592. [PMID: 34139166 PMCID: PMC8261833 DOI: 10.1016/j.cels.2021.05.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/19/2021] [Accepted: 05/14/2021] [Indexed: 12/25/2022]
Abstract
The rise of systems biology has ushered a new paradigm: the view of the cell as a system that processes environmental inputs to drive phenotypic outputs. Synthetic biology provides a complementary approach, allowing us to program cell behavior through the addition of synthetic genetic devices into the cellular processor. These devices, and the complex genetic circuits they compose, are engineered using a design-prototype-test cycle, allowing for predictable device performance to be achieved in a context-dependent manner. Within mammalian cells, context effects impact device performance at multiple scales, including the genetic, cellular, and extracellular levels. In order for synthetic genetic devices to achieve predictable behaviors, approaches to overcome context dependence are necessary. Here, we describe control systems approaches for achieving context-aware devices that are robust to context effects. We then consider cell fate programing as a case study to explore the potential impact of context-aware devices for regenerative medicine applications.
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Affiliation(s)
- Nika Shakiba
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Ross D Jones
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Ron Weiss
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Domitilla Del Vecchio
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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9
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Galas L, Burel C, Schapman D, Ropitaux M, Bernard S, Bénard M, Bardor M. Comparative Structural and Functional Analyses of the Fusiform, Oval, and Triradiate Morphotypes of Phaeodactylum tricornutum Pt3 Strain. FRONTIERS IN PLANT SCIENCE 2021; 12:638181. [PMID: 33912207 PMCID: PMC8072121 DOI: 10.3389/fpls.2021.638181] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 03/16/2021] [Indexed: 05/24/2023]
Abstract
The diatom Phaeodactylum tricornutum is a marine unicellular microalga that exists under three main morphotypes: oval, fusiform, and triradiate. Previous works have demonstrated that the oval morphotype of P. tricornutum Pt3 strain presents specific metabolic features. Here, we compared the cellular organization of the main morphotypes of the diatom P. tricornutum Pt3 strain through transmission electron and advanced light microscopies. The three morphotypes share similarities including spectral characteristics of the plastid, the location of the nucleus, the organization of mitochondria around the plastid as well as the existence of both a F-actin cortex, and an intracellular network of F-actin. In contrast, compared to fusiform and triradiate cells, oval cells spontaneously release proteins more rapidly. In addition, comparison of whole transcriptomes of oval versus fusiform or triradiate cells revealed numerous differential expression of positive and negative regulators belonging to the complex dynamic secretory machinery. This study highlights the specificities occurring within the oval morphotype underlying that the oval cells secrete proteins more rapidly.
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Affiliation(s)
- Ludovic Galas
- Normandie University, UNIROUEN, INSERM, PRIMACEN, Rouen, France
| | - Carole Burel
- Normandie University, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale (Glyco-MEV) EA4358, Rouen, France
| | - Damien Schapman
- Normandie University, UNIROUEN, INSERM, PRIMACEN, Rouen, France
| | - Marc Ropitaux
- Normandie University, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale (Glyco-MEV) EA4358, Rouen, France
| | - Sophie Bernard
- Normandie University, UNIROUEN, INSERM, PRIMACEN, Rouen, France
- Normandie University, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale (Glyco-MEV) EA4358, Rouen, France
| | - Magalie Bénard
- Normandie University, UNIROUEN, INSERM, PRIMACEN, Rouen, France
| | - Muriel Bardor
- Normandie University, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale (Glyco-MEV) EA4358, Rouen, France
- Institut Universitaire de France, Paris, France
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10
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Li ES, Saha MS. Optimizing Calcium Detection Methods in Animal Systems: A Sandbox for Synthetic Biology. Biomolecules 2021; 11:343. [PMID: 33668387 PMCID: PMC7996158 DOI: 10.3390/biom11030343] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/19/2021] [Accepted: 02/21/2021] [Indexed: 12/16/2022] Open
Abstract
Since the 1970s, the emergence and expansion of novel methods for calcium ion (Ca2+) detection have found diverse applications in vitro and in vivo across a series of model animal systems. Matched with advances in fluorescence imaging techniques, the improvements in the functional range and stability of various calcium indicators have significantly enhanced more accurate study of intracellular Ca2+ dynamics and its effects on cell signaling, growth, differentiation, and regulation. Nonetheless, the current limitations broadly presented by organic calcium dyes, genetically encoded calcium indicators, and calcium-responsive nanoparticles suggest a potential path toward more rapid optimization by taking advantage of a synthetic biology approach. This engineering-oriented discipline applies principles of modularity and standardization to redesign and interrogate endogenous biological systems. This review will elucidate how novel synthetic biology technologies constructed for eukaryotic systems can offer a promising toolkit for interfacing with calcium signaling and overcoming barriers in order to accelerate the process of Ca2+ detection optimization.
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Affiliation(s)
| | - Margaret S. Saha
- Department of Biology, College of William and Mary, Williamsburg, VA 23185, USA;
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11
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Martella A, Fisher DI. Regulation of Gene Expression and the Elucidative Role of CRISPR-Based Epigenetic Modifiers and CRISPR-Induced Chromosome Conformational Changes. CRISPR J 2021; 4:43-57. [PMID: 33616442 DOI: 10.1089/crispr.2020.0108] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In complex multicellular systems, gene expression is regulated at multiple stages through interconnected complex molecular pathways and regulatory networks. Transcription is the first step in gene expression and is subject to multiple layers of regulation in which epigenetic mechanisms such as DNA methylation, histone tail modifications, and chromosomal conformation play an essential role. In recent years, CRISPR-Cas9 systems have been employed to unearth this complexity and provide new insights on the contribution of chromatin dysregulation in the development of genetic diseases, as well as new tools to prevent or reverse this dysregulation. In this review, we outline the recent development of a variety of CRISPR-based epigenetic editors for targeted DNA methylation/demethylation, histone modification, and three-dimensional DNA conformational change, highlighting their relative performance and impact on gene regulation. Finally, we provide insights on the future developments aimed to accelerate our understanding of the causal relationship between epigenetic marks, genome organization, and gene regulation.
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Affiliation(s)
- Andrea Martella
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Cambridge, UK
| | - David I Fisher
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Cambridge, UK
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12
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Di Blasi R, Zouein A, Ellis T, Ceroni F. Genetic Toolkits to Design and Build Mammalian Synthetic Systems. Trends Biotechnol 2021; 39:1004-1018. [PMID: 33526300 DOI: 10.1016/j.tibtech.2020.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 12/14/2020] [Accepted: 12/14/2020] [Indexed: 11/17/2022]
Abstract
Construction of DNA-encoded programs is central to synthetic biology and the chosen method often determines the time required to design and build constructs for testing. Here, we describe and summarise key features of the available toolkits for DNA construction for mammalian cells. We compare the different cloning strategies based on their complexity and the time needed to generate constructs of different sizes, and we reflect on why Golden Gate toolkits now dominate due to their modular design. We look forward to future advances, including accessory packs for cloning toolkits that can facilitate editing, orthogonality, advanced regulation, and integration into synthetic chromosome construction.
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Affiliation(s)
- Roberto Di Blasi
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK; Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK
| | - Annalise Zouein
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK; Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK; Department of Bioengineering, Imperial College London, South Kensington Campus, London, UK
| | - Tom Ellis
- Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK; Department of Bioengineering, Imperial College London, South Kensington Campus, London, UK; Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Francesca Ceroni
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK; Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK.
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13
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Abstract
Reconstitution is an experimental strategy that seeks to recapitulate biological events outside their natural contexts using a reduced set of components. Classically, biochemical reconstitution has been extensively applied to identify the minimal set of molecules sufficient for recreating the basic chemistry of life. By analogy, reconstitution approaches to developmental biology recapitulate aspects of developmental events outside an embryo, with the goal of revealing the basic genetic circuits or physical cues sufficient for recreating developmental decisions. The rapidly growing repertoire of genetic, molecular, microscopic, and bioengineering tools is expanding the complexity and precision of reconstitution experiments. We review the emerging field of synthetic developmental biology, with a focus on the ways in which reconstitution strategies and new biological tools have enhanced our modern understanding of fundamental questions in developmental biology.
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Affiliation(s)
- Gavin Schlissel
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
| | - Pulin Li
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
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14
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Müller-McNicoll M, Rossbach O, Hui J, Medenbach J. Auto-regulatory feedback by RNA-binding proteins. J Mol Cell Biol 2020; 11:930-939. [PMID: 31152582 PMCID: PMC6884704 DOI: 10.1093/jmcb/mjz043] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/25/2019] [Accepted: 04/23/2019] [Indexed: 12/19/2022] Open
Abstract
RNA-binding proteins (RBPs) are key regulators in post-transcriptional control of gene expression. Mutations that alter their activity or abundance have been implicated in numerous diseases such as neurodegenerative disorders and various types of cancer. This highlights the importance of RBP proteostasis and the necessity to tightly control the expression levels and activities of RBPs. In many cases, RBPs engage in an auto-regulatory feedback by directly binding to and influencing the fate of their own mRNAs, exerting control over their own expression. For this feedback control, RBPs employ a variety of mechanisms operating at all levels of post-transcriptional regulation of gene expression. Here we review RBP-mediated autogenous feedback regulation that either serves to maintain protein abundance within a physiological range (by negative feedback) or generates binary, genetic on/off switches important for e.g. cell fate decisions (by positive feedback).
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Affiliation(s)
- Michaela Müller-McNicoll
- Institute of Cell Biology and Neuroscience, Goethe University Frankfurt, Max-von-Laue-Strasse 13, D-60438 Frankfurt am Main, Germany
| | - Oliver Rossbach
- Institute of Biochemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany
| | - Jingyi Hui
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jan Medenbach
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
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15
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Bojar D, Fussenegger M. The Role of Protein Engineering in Biomedical Applications of Mammalian Synthetic Biology. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1903093. [PMID: 31588687 DOI: 10.1002/smll.201903093] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/05/2019] [Indexed: 06/10/2023]
Abstract
Engineered proteins with enhanced or altered functionality, generated for example by mutation or domain fusion, are at the core of nearly all synthetic biology endeavors in the context of precision medicine, also known as personalized medicine. From designer receptors sensing elevated blood markers to effectors rerouting signaling pathways to synthetic transcription factors and the customized therapeutics they regulate, engineered proteins play a crucial role at every step of novel therapeutic approaches using synthetic biology. Here, recent developments in protein engineering aided by advances in directed evolution, de novo design, and machine learning are discussed. Building on clinical successes already achieved with chimeric antigen receptor (CAR-) T cells and other cell-based therapies, these developments are expected to further enhance the capabilities of mammalian synthetic biology in biomedical and other applications.
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Affiliation(s)
- Daniel Bojar
- ETH Zurich, Department of Biosystems Science and Engineering, Faculty of Life Science, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland
| | - Martin Fussenegger
- ETH Zurich, Department of Biosystems Science and Engineering, Faculty of Life Science, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland
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16
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Barbier I, Perez‐Carrasco R, Schaerli Y. Controlling spatiotemporal pattern formation in a concentration gradient with a synthetic toggle switch. Mol Syst Biol 2020; 16:e9361. [PMID: 32529808 PMCID: PMC7290156 DOI: 10.15252/msb.20199361] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 04/29/2020] [Accepted: 05/08/2020] [Indexed: 11/20/2022] Open
Abstract
The formation of spatiotemporal patterns of gene expression is frequently guided by gradients of diffusible signaling molecules. The toggle switch subnetwork, composed of two cross-repressing transcription factors, is a common component of gene regulatory networks in charge of patterning, converting the continuous information provided by the gradient into discrete abutting stripes of gene expression. We present a synthetic biology framework to understand and characterize the spatiotemporal patterning properties of the toggle switch. To this end, we built a synthetic toggle switch controllable by diffusible molecules in Escherichia coli. We analyzed the patterning capabilities of the circuit by combining quantitative measurements with a mathematical reconstruction of the underlying dynamical system. The toggle switch can produce robust patterns with sharp boundaries, governed by bistability and hysteresis. We further demonstrate how the hysteresis, position, timing, and precision of the boundary can be controlled, highlighting the dynamical flexibility of the circuit.
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Affiliation(s)
- Içvara Barbier
- Department of Fundamental MicrobiologyUniversity of LausanneLausanneSwitzerland
| | - Rubén Perez‐Carrasco
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonUK
- Department of MathematicsUniversity College LondonLondonUK
| | - Yolanda Schaerli
- Department of Fundamental MicrobiologyUniversity of LausanneLausanneSwitzerland
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17
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Mol AA, Groher F, Schreiber B, Rühmkorff C, Suess B. Robust gene expression control in human cells with a novel universal TetR aptamer splicing module. Nucleic Acids Res 2020; 47:e132. [PMID: 31504742 PMCID: PMC6846422 DOI: 10.1093/nar/gkz753] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/15/2019] [Accepted: 08/20/2019] [Indexed: 01/12/2023] Open
Abstract
Fine-tuning of gene expression is desirable for a wide range of applications in synthetic biology. In this context, RNA regulatory devices provide a powerful and highly functional tool. We developed a versatile, robust and reversible device to control gene expression by splicing regulation in human cells using an aptamer that is recognized by the Tet repressor TetR. Upon insertion in proximity to the 5′ splice site, intron retention can be controlled via the binding of TetR to the aptamer. Although we were able to demonstrate regulation for different introns, the genomic context had a major impact on regulation. In consequence, we advanced the aptamer to develop a splice device. Our novel device contains the aptamer integrated into a context of exonic and intronic sequences that create and maintain an environment allowing a reliable and robust splicing event. The exon-born, additional amino acids will then be cleaved off by a self-cleaving peptide. This design allows portability of the splicing device, which we confirmed by demonstrating its functionality in different gene contexts. Intriguingly, our splicing device shows a high dynamic range and low basal activity, i.e. desirable features that often prove a major challenge when implementing synthetic biology in mammalian cell lines.
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Affiliation(s)
- Adam A Mol
- Department of Biology, Technical University of Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Florian Groher
- Department of Biology, Technical University of Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Britta Schreiber
- Department of Biology, Technical University of Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Ciaran Rühmkorff
- Department of Biology, Technical University of Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Beatrix Suess
- Department of Biology, Technical University of Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
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18
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Sarsaiya S, Shi J, Chen J. Bioengineering tools for the production of pharmaceuticals: current perspective and future outlook. Bioengineered 2020; 10:469-492. [PMID: 31656120 PMCID: PMC6844412 DOI: 10.1080/21655979.2019.1682108] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The bioengineering tools have significant advantages through less time-consuming and utilized as a promising stage for the production of pharmaceutical bioproducts under the single platform. This review highlighted the advantages and current improvement in the plant, animal and microbial bioengineering tools and outlines feasible approaches by biological and process’s bioengineering levels for advancing the economic feasibility of pharmaceutical’s production. The critical analysis results revealed that system biology and synthetic biology along with advanced bioengineering tools like transcriptome, proteome, metabolome and nano bioengineering tools have shown a promising impact on the development of pharmaceutical’s bioproducts. Tools to overcome and resolve the accompanying encounters of pharmaceutical’s production that include nano bioengineering tools are also discussed. As a summary and prospect, it also gives new insight into the challenges and possible breakthrough of the development of pharmaceutical’s bioproducts through bioengineering tools.
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Affiliation(s)
- Surendra Sarsaiya
- Key Laboratory of Basic Pharmacology and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University , Zunyi , China.,Bioresource Institute for Healthy Utilization, Zunyi Medical University , Zunyi , China
| | - Jingshan Shi
- Key Laboratory of Basic Pharmacology and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University , Zunyi , China
| | - Jishuang Chen
- Bioresource Institute for Healthy Utilization, Zunyi Medical University , Zunyi , China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University , Nanjing , China
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19
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DeNies MS, Liu AP, Schnell S. Are the biomedical sciences ready for synthetic biology? Biomol Concepts 2020; 11:23-31. [PMID: 31982863 DOI: 10.1515/bmc-2020-0003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/02/2020] [Indexed: 11/15/2022] Open
Abstract
The ability to construct a functional system from its individual components is foundational to understanding how it works. Synthetic biology is a broad field that draws from principles of engineering and computer science to create new biological systems or parts with novel function. While this has drawn well-deserved acclaim within the biotechnology community, application of synthetic biology methodologies to study biological systems has potential to fundamentally change how biomedical research is conducted by providing researchers with improved experimental control. While the concepts behind synthetic biology are not new, we present evidence supporting why the current research environment is conducive for integration of synthetic biology approaches within biomedical research. In this perspective we explore the idea of synthetic biology as a discovery science research tool and provide examples of both top-down and bottom-up approaches that have already been used to answer important physiology questions at both the organismal and molecular level.
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Affiliation(s)
- Maxwell S DeNies
- Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Allen P Liu
- Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.,Department of Biophysics, University of Michigan, Ann Arbor, Michigan, USA
| | - Santiago Schnell
- Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Department of Computational Medicine & Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
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20
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Chang HJ, Bonnet J. Synthetic receptors to understand and control cellular functions. Methods Enzymol 2020; 633:143-167. [DOI: 10.1016/bs.mie.2019.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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21
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Zeng Y, Bhagyashree B, Zhao W, Nguyen T, Segatori L. Hysteretic Genetic Circuit for Detection of Proteasomal Degradation in Mammalian Cells. ACS Synth Biol 2019; 8:2025-2035. [PMID: 31415719 DOI: 10.1021/acssynbio.9b00074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Synthetic hysteretic mammalian gene circuits generating sustained cellular responses to transient perturbations provide important tools to investigate complex cellular behaviors and reprogram cells for a variety of applications, ranging from protein production to cell fate decisions. The design rules of synthetic gene circuits with controlled hysteretic behaviors, however, remain uncharacterized. To identify the criteria for achieving predictable control of hysteresis, we built a genetic circuit for detection of proteasomal degradation (Hys-Deg). The Hys-Deg circuit is based on a tetracycline-controlled transactivator (tTA) variant engineered to interface with the ubiquitin proteasome system (UPS). The tTA variant activates its own expression, generating a positive feedback loop that is triggered by expression of another tTA gene that is constitutively regulated. Guided by predictive modeling, we characterized the hysteretic response of the Hys-Deg circuit. We demonstrated that control of the hysteretic response is achieved by modulating the ratio of expression of constitutive to inducible tTA. We also showed that the system can be finely tuned through dosage of the inducer tetracycline to calibrate the circuit for detection of the desired levels of UPS activation. This study establishes the design rules for building a hysteretic genetic circuit with an autoregulatory feedback loop and provides a synthetic memory module that could be easily integrated into regulatory gene networks to study and engineer complex cellular behaviors.
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22
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Vogel M, Weigand JE, Kluge B, Grez M, Suess B. A small, portable RNA device for the control of exon skipping in mammalian cells. Nucleic Acids Res 2019; 46:e48. [PMID: 29420816 PMCID: PMC5934650 DOI: 10.1093/nar/gky062] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 01/29/2018] [Indexed: 12/17/2022] Open
Abstract
Splicing is an essential and highly regulated process in mammalian cells. We developed a synthetic riboswitch that efficiently controls alternative splicing of a cassette exon in response to the small molecule ligand tetracycline. The riboswitch was designed to control the accessibility of the 3' splice site by placing the latter inside the closing stem of a conformationally controlled tetracycline aptamer. In the presence of tetracycline, the cassette exon is skipped, whereas it is included in the ligand's absence. The design allows for an easy, context-independent integration of the regulatory device into any gene of interest. Portability of the device was shown through its functionality in four different systems: a synthetic minigene, a reporter gene and two endogenous genes. Furthermore, riboswitch functionality to control cellular signaling cascades was demonstrated by using it to specifically induce cell death through the conditionally controlled expression of CD20, which is a target in cancer therapy.
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Affiliation(s)
- Marc Vogel
- Department of Biology, Technical University Darmstadt, Schnittspahnstr. 10, 64287 Darmstadt, Germany
| | - Julia E Weigand
- Department of Biology, Technical University Darmstadt, Schnittspahnstr. 10, 64287 Darmstadt, Germany
| | - Britta Kluge
- Department of Biology, Technical University Darmstadt, Schnittspahnstr. 10, 64287 Darmstadt, Germany
| | - Manuel Grez
- Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Paul-Ehrlich-Str. 42-44, 60596 Frankfurt/M, Germany
| | - Beatrix Suess
- Department of Biology, Technical University Darmstadt, Schnittspahnstr. 10, 64287 Darmstadt, Germany
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23
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Tewary M, Shakiba N, Zandstra PW. Stem cell bioengineering: building from stem cell biology. Nat Rev Genet 2019; 19:595-614. [PMID: 30089805 DOI: 10.1038/s41576-018-0040-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
New fundamental discoveries in stem cell biology have yielded potentially transformative regenerative therapeutics. However, widespread implementation of stem-cell-derived therapeutics remains sporadic. Barriers that impede the development of these therapeutics can be linked to our incomplete understanding of how the regulatory networks that encode stem cell fate govern the development of the complex tissues and organs that are ultimately required for restorative function. Bioengineering tools, strategies and design principles represent core components of the stem cell bioengineering toolbox. Applied to the different layers of complexity present in stem-cell-derived systems - from gene regulatory networks in single stem cells to the systemic interactions of stem-cell-derived organs and tissues - stem cell bioengineering can address existing challenges and advance regenerative medicine and cellular therapies.
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Affiliation(s)
- Mukul Tewary
- Institute of Biomaterials and Biomedical Engineering (IBBME) and The Donnelly Centre for Cellular and Biomolecular Research (CCBR), University of Toronto, Toronto, Ontario, Canada.,Collaborative Program in Developmental Biology, University of Toronto, Toronto, Ontario, Canada
| | - Nika Shakiba
- Institute of Biomaterials and Biomedical Engineering (IBBME) and The Donnelly Centre for Cellular and Biomolecular Research (CCBR), University of Toronto, Toronto, Ontario, Canada
| | - Peter W Zandstra
- Institute of Biomaterials and Biomedical Engineering (IBBME) and The Donnelly Centre for Cellular and Biomolecular Research (CCBR), University of Toronto, Toronto, Ontario, Canada. .,Collaborative Program in Developmental Biology, University of Toronto, Toronto, Ontario, Canada. .,Michael Smith Laboratories and School of Biomedical Engineering, University of British Columbia, Vancouver, British Columbia, Canada.
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24
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Mathur M, Kim CM, Munro SA, Rudina SS, Sawyer EM, Smolke CD. Programmable mutually exclusive alternative splicing for generating RNA and protein diversity. Nat Commun 2019; 10:2673. [PMID: 31209208 PMCID: PMC6572816 DOI: 10.1038/s41467-019-10403-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/01/2019] [Indexed: 02/07/2023] Open
Abstract
Alternative splicing performs a central role in expanding genomic coding capacity and proteomic diversity. However, programming of splicing patterns in engineered biological systems remains underused. Synthetic approaches thus far have predominantly focused on controlling expression of a single protein through alternative splicing. Here, we describe a modular and extensible platform for regulating four programmable exons that undergo a mutually exclusive alternative splicing event to generate multiple functionally-distinct proteins. We present an intron framework that enforces the mutual exclusivity of two internal exons and demonstrate a graded series of consensus sequence elements of varying strengths that set the ratio of two mutually exclusive isoforms. We apply this framework to program the DNA-binding domains of modular transcription factors to differentially control downstream gene activation. This splicing platform advances an approach for generating diverse isoforms and can ultimately be applied to program modular proteins and increase coding capacity of synthetic biological systems.
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Affiliation(s)
- Melina Mathur
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Cameron M Kim
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Sarah A Munro
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
- Joint Initiative for Metrology in Biology, Stanford, CA, 94305, USA
- Genome-scale Measurements Group, National Institute of Standards and Technology, Stanford, CA, 94305, USA
- Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Shireen S Rudina
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Eric M Sawyer
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Christina D Smolke
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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25
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Zi Z. Molecular Engineering of the TGF-β Signaling Pathway. J Mol Biol 2019; 431:2644-2654. [PMID: 31121181 DOI: 10.1016/j.jmb.2019.05.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 05/05/2019] [Accepted: 05/13/2019] [Indexed: 12/19/2022]
Abstract
Transforming growth factor beta (TGF-β) is an important growth factor that plays essential roles in regulating tissue development and homeostasis. Dysfunction of TGF-β signaling is a hallmark of many human diseases. Therefore, targeting TGF-β signaling presents broad therapeutic potential. Since the discovery of the TGF-β ligand, a collection of engineered signaling proteins have been developed to probe and manipulate TGF-β signaling responses. In this review, we highlight recent progress in the engineering of TGF-β signaling for different applications and discuss how molecular engineering approaches can advance our understanding of this important pathway. In addition, we provide a future outlook on the opportunities and challenges in the engineering of the TGF-β signaling pathway from a quantitative perspective.
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Affiliation(s)
- Zhike Zi
- Otto-Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
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26
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Healy CP, Deans TL. Genetic circuits to engineer tissues with alternative functions. J Biol Eng 2019; 13:39. [PMID: 31073328 PMCID: PMC6500048 DOI: 10.1186/s13036-019-0170-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/17/2019] [Indexed: 12/23/2022] Open
Abstract
Persistent and complex problems arising with respect to human physiology and pathology have led to intense investigation into therapies and tools that permit more targeted outcomes and biomimetic responses to pathological conditions. A primary goal in mammalian synthetic biology is to build genetic circuits that exert fine control over cell behavior for next-generation biomedical applications. In pursuit of this, synthetic biologists have engineered cells endowed with genetic circuits with sensor that are capable of reacting to a variety of stimuli and responding with targeted behavior. Here, we highlight how synthetic biology approaches are being used to program cells with novel functions for therapeutic applications, and how they can be used in stem cells to improve differentiation outcomes. These approaches open the possibilities for engineering synthetic tissues for employing personalized medicine and to develop next-generation biomedical therapies.
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Affiliation(s)
- C P Healy
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112 USA
| | - T L Deans
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112 USA
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27
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Wang J, Isaacson SA, Belta C. Modeling Genetic Circuit Behavior in Transiently Transfected Mammalian Cells. ACS Synth Biol 2019; 8:697-707. [PMID: 30884948 DOI: 10.1021/acssynbio.8b00166] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Binning cells by plasmid copy number is a common practice for analyzing transient transfection data. In many kinetic models of transfected cells, protein production rates are assumed to be proportional to plasmid copy number. The validity of this assumption in transiently transfected mammalian cells is not clear; models based on this assumption appear unable to reproduce experimental flow cytometry data robustly. We hypothesize that protein saturation at high plasmid copy number is a reason previous models break down and validate our hypothesis by comparing experimental data and a stochastic chemical kinetics model. The model demonstrates that there are multiple distinct physical mechanisms that can cause saturation. On the basis of these observations, we develop a novel minimal bin-dependent ODE model that assumes different parameters for protein production in cells with low versus high numbers of plasmids. Compared to a traditional Hill-function-based model, the bin-dependent model requires only one additional parameter, but fits flow cytometry input-output data for individual modules up to twice as accurately. By composing together models of individually fit modules, we use the bin-dependent model to predict the behavior of six cascades and three feed-forward circuits. The bin-dependent models are shown to provide more accurate predictions on average than corresponding (composed) Hill-function-based models and predictions of comparable accuracy to EQuIP, while still providing a minimal ODE-based model that should be easy to integrate as a subcomponent within larger differential equation circuit models. Our analysis also demonstrates that accounting for batch effects is important in developing accurate composed models.
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Affiliation(s)
- Junmin Wang
- The Bioinformatics Graduate Program, Boston University, Boston, Massachusetts 02215, United States
| | - Samuel A. Isaacson
- Department of Mathematics, Boston University, Boston, Massachusetts 02215, United States
| | - Calin Belta
- The Bioinformatics Graduate Program, Boston University, Boston, Massachusetts 02215, United States
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28
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Gardner E, Ellington A. Reprogramming the brain with synthetic neurobiology. Curr Opin Biotechnol 2018; 58:37-44. [PMID: 30458406 DOI: 10.1016/j.copbio.2018.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 10/26/2018] [Indexed: 12/28/2022]
Abstract
The mammalian brain is among the most complex organs known in biology. Historically, neuroscience techniques have consisted primarily of low-throughput microscopy and electrophysiological approaches. While these methods will continue to serve the community, the emerging field of synthetic neurobiology may be better equipped to scale with systems neuroscience. By using genetic techniques to achieve cell-type specificity, a map of the connectome, neural activation and recording, and ultimately to program neural development itself, we can begin to build a better framework with which to understand the brain's mechanisms.
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Affiliation(s)
- Elizabeth Gardner
- Center for Systems and Synthetic Biology, Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas, 2500 Speedway, Austin, TX 78712, USA
| | - Andrew Ellington
- Center for Systems and Synthetic Biology, Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas, 2500 Speedway, Austin, TX 78712, USA.
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29
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Polyprotein strategy for stoichiometric assembly of nitrogen fixation components for synthetic biology. Proc Natl Acad Sci U S A 2018; 115:E8509-E8517. [PMID: 30061389 PMCID: PMC6130400 DOI: 10.1073/pnas.1804992115] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The requirement of maintaining balanced expression of a large number of gene products represents a major challenge to the engineering of nitrogen fixation in cereal crops, necessitating reiterative combinatorial assembly cycles to optimize monocistronic gene expression. In this study, we have explored a “fuse-and-cleave” virus-derived polyprotein strategy to reduce gene numbers and achieve balanced expression of protein components required for nitrogenase biosynthesis and activity. After testing and regrouping assemblies on the basis of expression profiles, cleavage patterns, and activity, 14 essential genes were selectively assembled into 5 giant genes that enable growth on dinitrogen. This strategy has potential advantages, not only for transferring nitrogen fixation to plants, but also for the engineering of other complex systems of profound agronomic and ecological importance. Re-engineering of complex biological systems (CBS) is an important goal for applications in synthetic biology. Efforts have been made to simplify CBS by refactoring a large number of genes with rearranged polycistrons and synthetic regulatory circuits. Here, a posttranslational protein-splicing strategy derived from RNA viruses was exploited to minimize gene numbers of the classic nitrogenase system, where the expression stoichiometry is particularly important. Operon-based nif genes from Klebsiella oxytoca were regrouped into giant genes either by fusing genes together or by expressing polyproteins that are subsequently cleaved with Tobacco Etch Virus protease. After several rounds of selection based on protein expression levels and tolerance toward a remnant C-terminal ENLYFQ-tail, a system with only five giant genes showed optimal nitrogenase activity and supported diazotrophic growth of Escherichia coli. This study provides an approach for efficient translation from an operon-based system into a polyprotein-based assembly that has the potential for portable and stoichiometric expression of the complex nitrogenase system in eukaryotic organisms.
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30
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Weisenberger MS, Deans TL. Bottom-up approaches in synthetic biology and biomaterials for tissue engineering applications. J Ind Microbiol Biotechnol 2018; 45:599-614. [PMID: 29552703 PMCID: PMC6041164 DOI: 10.1007/s10295-018-2027-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 03/11/2018] [Indexed: 12/30/2022]
Abstract
Synthetic biologists use engineering principles to design and construct genetic circuits for programming cells with novel functions. A bottom-up approach is commonly used to design and construct genetic circuits by piecing together functional modules that are capable of reprogramming cells with novel behavior. While genetic circuits control cell operations through the tight regulation of gene expression, a diverse array of environmental factors within the extracellular space also has a significant impact on cell behavior. This extracellular space offers an addition route for synthetic biologists to apply their engineering principles to program cell-responsive modules within the extracellular space using biomaterials. In this review, we discuss how taking a bottom-up approach to build genetic circuits using DNA modules can be applied to biomaterials for controlling cell behavior from the extracellular milieu. We suggest that, by collectively controlling intrinsic and extrinsic signals in synthetic biology and biomaterials, tissue engineering outcomes can be improved.
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Affiliation(s)
| | - Tara L Deans
- Department of Bioengineering, University of Utah, Salt Lake City, UT, 84112, USA.
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31
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Perez-Carrasco R, Barnes CP, Schaerli Y, Isalan M, Briscoe J, Page KM. Combining a Toggle Switch and a Repressilator within the AC-DC Circuit Generates Distinct Dynamical Behaviors. Cell Syst 2018; 6:521-530.e3. [PMID: 29574056 PMCID: PMC5929911 DOI: 10.1016/j.cels.2018.02.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/14/2017] [Accepted: 02/13/2018] [Indexed: 11/16/2022]
Abstract
Although the structure of a genetically encoded regulatory circuit is an important determinant of its function, the relationship between circuit topology and the dynamical behaviors it can exhibit is not well understood. Here, we explore the range of behaviors available to the AC-DC circuit. This circuit consists of three genes connected as a combination of a toggle switch and a repressilator. Using dynamical systems theory, we show that the AC-DC circuit exhibits both oscillations and bistability within the same region of parameter space; this generates emergent behaviors not available to either the toggle switch or the repressilator alone. The AC-DC circuit can switch on oscillations via two distinct mechanisms, one of which induces coherence into ensembles of oscillators. In addition, we show that in the presence of noise, the AC-DC circuit can behave as an excitable system capable of spatial signal propagation or coherence resonance. Together, these results demonstrate how combinations of simple motifs can exhibit multiple complex behaviors.
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Affiliation(s)
- Ruben Perez-Carrasco
- Department of Mathematics, University College London, Gower Street, WC1E 6BT London, UK.
| | - Chris P Barnes
- Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT London, UK; Department of Genetics, Evolution and Environment, University College London, Gower Street, WC1E 6BT London, UK
| | - Yolanda Schaerli
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland
| | - Mark Isalan
- Department of Life Sciences, Imperial College London, SW7 2AZ London, UK
| | - James Briscoe
- The Francis Crick Institute, 1 Midland Road, NW1 1AT London, UK
| | - Karen M Page
- Department of Mathematics, University College London, Gower Street, WC1E 6BT London, UK
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32
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Maeda K, Kurata H. Long negative feedback loop enhances period tunability of biological oscillators. J Theor Biol 2018; 440:21-31. [PMID: 29253507 DOI: 10.1016/j.jtbi.2017.12.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 12/08/2017] [Accepted: 12/14/2017] [Indexed: 11/18/2022]
Abstract
Oscillatory phenomena play a major role in organisms. In some biological oscillations such as cell cycles and heartbeats, the period can be tuned without significant changes in the amplitude. This property is called (period) tunability, one of the prominent features of biological oscillations. However, how biological oscillators produce tunable oscillations remains largely unexplored. We tackle this question using computational experiments. It has been reported that positive-plus-negative feedback oscillators produce tunable oscillations through the hysteresis-based mechanism. First, in this study, we confirmed that positive-plus-negative feedback oscillators generate tunable oscillations. Second, we found that tunability is positively correlated with the dynamic range of oscillations. Third, we showed that long negative feedback oscillators without any additional positive feedback loops can produce tunable oscillations. Finally, we computationally demonstrated that by lengthening the negative feedback loop, the Repressilator, known as a non-tunable synthetic gene oscillator, can be converted into a tunable oscillator. This work provides synthetic biologists with clues to design tunable gene oscillators.
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Affiliation(s)
- Kazuhiro Maeda
- Frontier Research Academy for Young Researchers, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata, Kitakyushu, Fukuoka 804-8550, Japan; Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan.
| | - Hiroyuki Kurata
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan; Biomedical Informatics R&D Center, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan.
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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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Abstract
The past several years have seen an explosion in development of applications for the CRISPR-Cas9 system, from efficient genome editing, to high-throughput screening, to recruitment of a range of DNA and chromatin-modifying enzymes. While homology-directed repair (HDR) coupled with Cas9 nuclease cleavage has been used with great success to repair and re-write genomes, recently developed base-editing systems present a useful orthogonal strategy to engineer nucleotide substitutions. Base editing relies on recruitment of cytidine deaminases to introduce changes (rather than double-stranded breaks and donor templates) and offers potential improvements in efficiency while limiting damage and simplifying the delivery of editing machinery. At the same time, these systems enable novel mutagenesis strategies to introduce sequence diversity for engineering and discovery. Here, we review the different base-editing platforms, including their deaminase recruitment strategies and editing outcomes, and compare them to other CRISPR genome-editing technologies. Additionally, we discuss how these systems have been applied in therapeutic, engineering, and research settings. Lastly, we explore future directions of this emerging technology.
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Hess GT, Tycko J, Yao D, Bassik MC. Methods and Applications of CRISPR-Mediated Base Editing in Eukaryotic Genomes. Mol Cell 2017; 68:26-43. [PMID: 28985508 PMCID: PMC5997582 DOI: 10.1016/j.molcel.2017.09.029] [Citation(s) in RCA: 153] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 12/26/2022]
Abstract
The past several years have seen an explosion in development of applications for the CRISPR-Cas9 system, from efficient genome editing, to high-throughput screening, to recruitment of a range of DNA and chromatin-modifying enzymes. While homology-directed repair (HDR) coupled with Cas9 nuclease cleavage has been used with great success to repair and re-write genomes, recently developed base-editing systems present a useful orthogonal strategy to engineer nucleotide substitutions. Base editing relies on recruitment of cytidine deaminases to introduce changes (rather than double-stranded breaks and donor templates) and offers potential improvements in efficiency while limiting damage and simplifying the delivery of editing machinery. At the same time, these systems enable novel mutagenesis strategies to introduce sequence diversity for engineering and discovery. Here, we review the different base-editing platforms, including their deaminase recruitment strategies and editing outcomes, and compare them to other CRISPR genome-editing technologies. Additionally, we discuss how these systems have been applied in therapeutic, engineering, and research settings. Lastly, we explore future directions of this emerging technology.
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Affiliation(s)
- Gaelen T Hess
- Department of Genetics and Stanford University Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford, CA, USA
| | - Josh Tycko
- Department of Genetics and Stanford University Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford, CA, USA
| | - David Yao
- Department of Genetics and Stanford University Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford, CA, USA
| | - Michael C Bassik
- Department of Genetics and Stanford University Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford, CA, USA.
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