201
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Liu LD, Huang M, Dai P, Liu T, Fan S, Cheng X, Zhao Y, Yeap LS, Meng FL. Intrinsic Nucleotide Preference of Diversifying Base Editors Guides Antibody Ex Vivo Affinity Maturation. Cell Rep 2019; 25:884-892.e3. [PMID: 30355495 DOI: 10.1016/j.celrep.2018.09.090] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/13/2018] [Accepted: 09/27/2018] [Indexed: 12/27/2022] Open
Abstract
Base editors (BEs) are emerging tools used for precision correction or diversifying mutation. It provides a potential way to recreate somatic hypermutations (SHM) for generating high-affinity antibody, which is usually screened from antigen-challenged animal models or synthetic combinatorial libraries. By comparing somatic mutations in the same genomic context, we screened engineered deaminases and CRISPR-deaminase coupling approaches and updated diversifying base editors (DBEs) to generate SHM. The deaminase used in DBEs retains its intrinsic nucleotide preference and mutates cytidines at its preferred motifs. DBE with AID targets the same hotspots as physiological AID does in vivo, while DBE with other deaminases generates distinct mutation profiles from the same DNA substrate. Downstream DNA repair pathways further diversified the sequence, while Cas9-nickase restricted mutation spreading. Finally, application of DBE in an antibody display system achieved antibody affinity maturation ex vivo. Our findings provide insight of DBE working mechanism and an alternative antibody engineering approach.
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Affiliation(s)
- Liu Daisy Liu
- 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, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Min Huang
- 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, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Pengfei Dai
- 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, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Tingting Liu
- 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, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Shuangshuang Fan
- 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, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Xueqian Cheng
- State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, China
| | - Yaofeng Zhao
- State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, China
| | - Leng-Siew Yeap
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Fei-Long Meng
- 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, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
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202
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Evanoff M, Komor AC. Base Editors: Modular Tools for the Introduction of Point Mutations in Living Cells. Emerg Top Life Sci 2019; 3:483-491. [PMID: 32270050 PMCID: PMC7141416 DOI: 10.1042/etls20190088] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Base editors are a new family of programmable genome editing tools that fuse ssDNA (single stranded DNA) modifying enzymes to catalytically inactive CRISPR-associated (Cas) endonucleases to induce highly efficient single base changes. With dozens of base editors now reported, it is apparent that these tools are highly modular; many combinations of ssDNA modifying enzymes and Cas proteins have resulted in a variety of base editors, each with its own unique properties and potential uses. In this perspective, we describe currently available base editors, highlighting their modular nature and describing the various options available for each component. Furthermore, we briefly discuss applications in synthetic biology and genome engineering where base editors have presented unique advantages over alternative techniques.
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Affiliation(s)
- Mallory Evanoff
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093
| | - Alexis C. Komor
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093
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203
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Molla KA, Yang Y. CRISPR/Cas-Mediated Base Editing: Technical Considerations and Practical Applications. Trends Biotechnol 2019; 37:1121-1142. [PMID: 30995964 DOI: 10.1016/j.tibtech.2019.03.008] [Citation(s) in RCA: 192] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 12/26/2022]
Affiliation(s)
- Kutubuddin A Molla
- Department of Plant Pathology and Environmental Microbiology, and Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA; ICAR-National Rice Research Institute, Cuttack 753006, India
| | - Yinong Yang
- Department of Plant Pathology and Environmental Microbiology, and Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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204
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Grisch-Chan HM, Schwank G, Harding CO, Thöny B. State-of-the-Art 2019 on Gene Therapy for Phenylketonuria. Hum Gene Ther 2019; 30:1274-1283. [PMID: 31364419 PMCID: PMC6763965 DOI: 10.1089/hum.2019.111] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/22/2019] [Indexed: 12/21/2022] Open
Abstract
Phenylketonuria (PKU) is considered to be a paradigm for a monogenic metabolic disorder but was never thought to be a primary application for human gene therapy due to established alternative treatment. However, somewhat unanticipated improvement in neuropsychiatric outcome upon long-term treatment of adults with PKU with enzyme substitution therapy might slowly change this assumption. In parallel, PKU was for a long time considered to be an excellent test system for experimental gene therapy of a Mendelian autosomal recessive defect of the liver due to an outstanding mouse model and the easy to analyze and well-defined therapeutic end point, that is, blood l-phenylalanine concentration. Lifelong treatment by targeting the mouse liver (or skeletal muscle) was achieved using different approaches, including (1) recombinant adeno-associated viral (rAAV) or nonviral naked DNA vector-based gene addition, (2) genome editing using base editors delivered by rAAV vectors, and (3) by delivering rAAVs for promoter-less insertion of the PAH-cDNA into the Pah locus. In this article we summarize the gene therapeutic attempts of correcting a mouse model for PKU and discuss the future implications for human gene therapy.
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Affiliation(s)
- Hiu Man Grisch-Chan
- Division of Metabolism, University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
| | - Gerald Schwank
- Department of Biology, Institute for Molecular Health Sciences, ETH Zurich, Zurich, Switzerland
| | - Cary O. Harding
- Department of Molecular and Medical Genetics, School of Medicine, Oregon Science and Health University, Portland, Oregon
| | - Beat Thöny
- Division of Metabolism, University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
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205
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Katayama K, Mitsunobu H, Nishida K. Mammalian synthetic biology by CRISPRs engineering and applications. Curr Opin Chem Biol 2019; 52:79-84. [DOI: 10.1016/j.cbpa.2019.05.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 05/21/2019] [Accepted: 05/23/2019] [Indexed: 10/26/2022]
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206
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Abstract
Base editing is a genome editing strategy that induces specific single-nucleotide changes within genomic DNA. Two major DNA base editors, cytosine base editors and adenine base editors, that consist of a Cas9 protein linked to a deaminase enzyme that catalyzes targeted base conversion directed by a single-guide RNA have been developed. This strategy has been used widely for precise genome editing because, unlike CRISPR-Cas nuclease-based genome editing systems, this strategy does not create double-strand DNA breaks that often result in high levels of undesirable indels. However, recent papers have reported that DNA base editors can cause substantial off-target editing in both genomic DNA and RNA. The off-target editing described in these studies is primarily independent of guide RNA and arises from the promiscuous reactivity of the deaminase enzymes used in DNA base editors. In this Perspective, we discuss the development of DNA base editors, the guide RNA-independent off-target activity reported in recent studies, and strategies that improve the selectivity of DNA base editors.
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Affiliation(s)
- SeHee Park
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
| | - Peter A. Beal
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, USA
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207
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Roccio M, Edge ASB. Inner ear organoids: new tools to understand neurosensory cell development, degeneration and regeneration. Development 2019; 146:146/17/dev177188. [PMID: 31477580 DOI: 10.1242/dev.177188] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of therapeutic interventions for hearing loss requires fundamental knowledge about the signaling pathways controlling tissue development as well as the establishment of human cell-based assays to validate therapeutic strategies ex vivo Recent advances in the field of stem cell biology and organoid culture systems allow the expansion and differentiation of tissue-specific progenitors and pluripotent stem cells in vitro into functional hair cells and otic-like neurons. We discuss how inner ear organoids have been developed and how they offer for the first time the opportunity to validate drug-based therapies, gene-targeting approaches and cell replacement strategies.
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Affiliation(s)
- Marta Roccio
- Inner Ear Research Laboratory, Department of Biomedical Research (DBMR), University of Bern, Bern 3008, Switzerland .,Department of Otorhinolaryngology, Head & Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern 3010, Switzerland
| | - Albert S B Edge
- Department of Otolaryngology, Harvard Medical School, Boston, MA 02115, USA.,Eaton-Peabody Laboratory, Massachusetts Eye and Ear, Boston, MA 02114, USA.,Harvard Stem Cell Institute, Cambridge, MA 02138, USA
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208
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Thuronyi BW, Koblan LW, Levy JM, Yeh WH, Zheng C, Newby GA, Wilson C, Bhaumik M, Shubina-Oleinik O, Holt JR, Liu DR. Continuous evolution of base editors with expanded target compatibility and improved activity. Nat Biotechnol 2019; 37:1070-1079. [PMID: 31332326 PMCID: PMC6728210 DOI: 10.1038/s41587-019-0193-0] [Citation(s) in RCA: 205] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 06/14/2019] [Indexed: 12/15/2022]
Abstract
Base editors use DNA-modifying enzymes targeted with a catalytically impaired CRISPR protein to precisely install point mutations. Here, we develop phage-assisted continuous evolution of base editors (BE-PACE) to improve their editing efficiency and target sequence compatibility. We used BE-PACE to evolve cytosine base editors (CBEs) that overcome target sequence context constraints of canonical CBEs. One evolved CBE, evoAPOBEC1-BE4max, is up to 26-fold more efficient at editing cytosine in the GC context, a disfavored context for wild-type APOBEC1 deaminase, while maintaining efficient editing in all other sequence contexts tested. Another evolved deaminase, evoFERNY, is 29% smaller than APOBEC1 and edits efficiently in all tested sequence contexts. We also evolved a CBE based on CDA1 deaminase with much higher editing efficiency at difficult target sites. Finally, we used data from evolved CBEs to illuminate the relationship between deaminase activity, base editing efficiency, editing window width and byproduct formation. These findings establish a system for rapid evolution of base editors and inform their use and improvement.
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Affiliation(s)
- B W Thuronyi
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Chemistry, Williams College, Williamstown, MA, USA
| | - Luke W Koblan
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Jonathan M Levy
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Wei-Hsi Yeh
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA, USA
| | - Christine Zheng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Gregory A Newby
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Christopher Wilson
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Mantu Bhaumik
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Olga Shubina-Oleinik
- Departments of Otolaryngology and Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Jeffrey R Holt
- Departments of Otolaryngology and Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA.
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209
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210
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Cheng TL, Li S, Yuan B, Wang X, Zhou W, Qiu Z. Expanding C-T base editing toolkit with diversified cytidine deaminases. Nat Commun 2019; 10:3612. [PMID: 31399578 PMCID: PMC6689024 DOI: 10.1038/s41467-019-11562-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 07/19/2019] [Indexed: 12/25/2022] Open
Abstract
Base editing tools for cytosine to thymine (C–T) conversion enable genome manipulation at single base-pair resolution with high efficiency. Available base editors (BEs) for C–T conversion (CBEs) have restricted editing scopes and nonnegligible off-target effects, which limit their applications. Here, by screening diversified lamprey cytidine deaminases, we establish various CBEs with expanded and diversified editing scopes, which could be further refined by various fusing strategies, fusing at either N-terminus or C–terminus of nCas9. Furthermore, off-target analysis reveals that several CBEs display improved fidelity. Our study expands the toolkits for C–T conversion, serves as guidance for appropriate choice and offers a framework for benchmarking future improvement of base editing tools. Cytosine base editors are limited by editing scope and potential off-target effects. Here the authors screen diversified lamprey cytidine deaminases along with different protein fusion architectures and present base editors with improved fidelity.
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Affiliation(s)
- Tian-Lin Cheng
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Shuo Li
- Department of interventional Radiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China
| | - Bo Yuan
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xiaolin Wang
- Department of interventional Radiology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China.,Shanghai Institute of Medical Imaging, Shanghai, 200032, China
| | - Wenhao Zhou
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, 201102, China
| | - Zilong Qiu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
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211
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Abstract
The prokaryote-derived CRISPR-Cas genome editing systems have transformed our ability to manipulate, detect, image and annotate specific DNA and RNA sequences in living cells of diverse species. The ease of use and robustness of this technology have revolutionized genome editing for research ranging from fundamental science to translational medicine. Initial successes have inspired efforts to discover new systems for targeting and manipulating nucleic acids, including those from Cas9, Cas12, Cascade and Cas13 orthologues. Genome editing by CRISPR-Cas can utilize non-homologous end joining and homology-directed repair for DNA repair, as well as single-base editing enzymes. In addition to targeting DNA, CRISPR-Cas-based RNA-targeting tools are being developed for research, medicine and diagnostics. Nuclease-inactive and RNA-targeting Cas proteins have been fused to a plethora of effector proteins to regulate gene expression, epigenetic modifications and chromatin interactions. Collectively, the new advances are considerably improving our understanding of biological processes and are propelling CRISPR-Cas-based tools towards clinical use in gene and cell therapies.
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Affiliation(s)
- Adrian Pickar-Oliver
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Genomic and Computational Biology, Duke University, Durham, NC, USA
| | - Charles A Gersbach
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Center for Genomic and Computational Biology, Duke University, Durham, NC, USA.
- Department of Surgery, Duke University Medical Center, Durham, NC, USA.
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212
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Wang Y, Liu Y, Li J, Yang Y, Ni X, Cheng H, Huang T, Guo Y, Ma H, Zheng P, Wang M, Sun J, Ma Y. Expanding targeting scope, editing window, and base transition capability of base editing in
Corynebacterium glutamicum. Biotechnol Bioeng 2019; 116:3016-3029. [DOI: 10.1002/bit.27121] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/03/2019] [Accepted: 07/08/2019] [Indexed: 01/02/2023]
Affiliation(s)
- Yu Wang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Ye Liu
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Junwei Li
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
- College of BiotechnologyTianjin University of Science and Technology Tianjin China
| | - Yi Yang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Xiaomeng Ni
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Haijiao Cheng
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Teng Huang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Yanmei Guo
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Hongwu Ma
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Ping Zheng
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Meng Wang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Jibin Sun
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
| | - Yanhe Ma
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial BiotechnologyChinese Academy of Sciences Tianjin China
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213
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Li G, Zhou S, Li C, Cai B, Yu H, Ma B, Huang Y, Ding Y, Liu Y, Ding Q, He C, Zhou J, Wang Y, Zhou G, Li Y, Yan Y, Hua J, Petersen B, Jiang Y, Sonstegard T, Huang X, Chen Y, Wang X. Base pair editing in goat: nonsense codon introgression into FGF5 results in longer hair. FEBS J 2019; 286:4675-4692. [PMID: 31276295 DOI: 10.1111/febs.14983] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/21/2019] [Accepted: 07/03/2019] [Indexed: 12/26/2022]
Abstract
The ability to alter single bases without homology directed repair (HDR) of double-strand breaks provides a potential solution for editing livestock genomes for economic traits, which are often multigenic. Progress toward multiplex editing in large animals has been hampered by the costly inefficiencies of HDR via microinjection of in vitro manipulated embryos. Here, we designed sgRNAs to induce nonsense codons (C-to-T transitions) at four target sites in caprine FGF5, which is a crucial regulator of hair length in mammals. Initial transfections of the third generation Base Editor (BE3) plasmid and four different sgRNAs into caprine fibroblasts were ineffective in altering FGF5. In contrast, all five progenies produced from microinjected single-cell embryos had alleles with a targeted nonsense mutation. The effectiveness of BE3 to make single base changes varied considerably based on sgRNA design. In addition, the rate of mosaicism differed between animals, target sites, and tissue type. The phenotypic effects on hair fiber were characterized by hematoxylin and eosin, immunofluorescence staining, and western blotting. Differences in morphology were detectable, even though mosaicism was probably affecting the levels of FGF5 expression. PCR amplicon and whole-genome resequencing analyses for off-target changes caused by BE3 were low at a genome-wide scale. This study provided the first evidence of base editing in large mammals produced from microinjected single-cell embryos. Our results support further optimization of BEs for introgressing complex human disease alleles into large animal models, to evaluate potential genetic improvement of complex health and production traits in a single generation.
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Affiliation(s)
- Guanwei Li
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Shiwei Zhou
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Chao Li
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Bei Cai
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Honghao Yu
- College of Biotechnology, Guilin Medical University, China
| | - Baohua Ma
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yu Huang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Yige Ding
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Yao Liu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Qiang Ding
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Chong He
- College of Information and Engineering, Northwest A&F University, Yangling, China
| | - Jiankui Zhou
- School of Life Science and Technology, ShanghaiTech University, China
| | - Ying Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Guangxian Zhou
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Yan Li
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Yuan Yan
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Jinlian Hua
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Bjoern Petersen
- Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut, Neustadt, Germany
| | - Yu Jiang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | | | - Xingxu Huang
- School of Life Science and Technology, ShanghaiTech University, China
| | - Yulin Chen
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Xiaolong Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, China
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214
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Schatoff EM, Zafra MP, Dow LE. Base editing the mammalian genome. Methods 2019; 164-165:100-108. [PMID: 30836137 PMCID: PMC6684841 DOI: 10.1016/j.ymeth.2019.02.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/27/2019] [Indexed: 02/03/2023] Open
Abstract
Base editing is a powerful technology that enables programmable conversion of single nucleotides in the mammalian genome. Base editors consist of a partially active Cas9 nuclease (Cas9D10A) tethered to a natural or synthetic DNA modifying enzyme. Though only recently described, BE has already shown enormous potential for basic and translational research, allowing the creation or repair of disease alleles in a variety of cell types and model organisms. In the past 2 years, a vast array of new and modified base editor variants have been described, expanding the flexibility and usefulness of the approach. Though simple in concept, effective implementation of base editing requires an understanding of the advantages and limitations of each of these tools. Here, we provide an overview of the concepts of DNA base editing, and discuss the recent progress toward the development of optimized base editing systems for mammalian cells. In addition, we highlight key technical aspects of designing and executing BE experiments, and provide detailed experimental examples of successful base editing in cell lines and organoids to help guide the effective use of these tools for genome modification.
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Affiliation(s)
- Emma M Schatoff
- Sandra and Edward Meyer Cancer Center, United States; Weill Cornell/Rockefeller/Sloan Kettering Tri-I MD-PhD Program, New York 10065, United States
| | - Maria Paz Zafra
- Sandra and Edward Meyer Cancer Center, United States; Department of Medicine, United States
| | - Lukas E Dow
- Sandra and Edward Meyer Cancer Center, United States; Department of Medicine, United States; Department of Biochemistry, Weill Cornell Medicine, New York 10021, United States.
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215
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Kim D, Luk K, Wolfe SA, Kim JS. Evaluating and Enhancing Target Specificity of Gene-Editing Nucleases and Deaminases. Annu Rev Biochem 2019; 88:191-220. [PMID: 30883196 DOI: 10.1146/annurev-biochem-013118-111730] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Programmable nucleases and deaminases, which include zinc-finger nucleases, transcription activator-like effector nucleases, CRISPR RNA-guided nucleases, and RNA-guided base editors, are now widely employed for the targeted modification of genomes in cells and organisms. These gene-editing tools hold tremendous promise for therapeutic applications. Importantly, these nucleases and deaminases may display off-target activity through the recognition of near-cognate DNA sequences to their target sites, resulting in collateral damage to the genome in the form of local mutagenesis or genomic rearrangements. For therapeutic genome-editing applications with these classes of programmable enzymes, it is essential to measure and limit genome-wide off-target activity. Herein, we discuss the key determinants of off-target activity for these systems. We describe various cell-based and cell-free methods for identifying genome-wide off-target sites and diverse strategies that have been developed for reducing the off-target activity of programmable gene-editing enzymes.
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Affiliation(s)
- Daesik Kim
- Center for Genome Engineering, Institute for Basic Science, Daejeon 34126, Republic of Korea;
| | - Kevin Luk
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA;
| | - Scot A Wolfe
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA;
| | - Jin-Soo Kim
- Center for Genome Engineering, Institute for Basic Science, Daejeon 34126, Republic of Korea;
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
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216
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Attenuation of Inherited and Acquired Retinal Degeneration Progression with Gene-based Techniques. Mol Diagn Ther 2019; 23:113-120. [PMID: 30569401 DOI: 10.1007/s40291-018-0377-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Inherited retinal dystrophies cause progressive vision loss and are major contributors to blindness worldwide. Advances in gene therapy have brought molecular approaches into the realm of clinical trials for these incurable illnesses. Select phase I, II and III trials are complete and provide some promise in terms of functional outcomes and safety, although questions do remain over the durability of their effects and the prevalence of inflammatory reactions. This article reviews gene therapy as it can be applied to inherited retinal dystrophies, provides an update of results from recent clinical trials, and discusses the future prospects of gene therapy and genome surgery.
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217
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Ahmadzadeh V, Farajnia S, Baghban R, Rahbarnia L, Zarredar H. CRISPR-Cas system: Toward a more efficient technology for genome editing and beyond. J Cell Biochem 2019; 120:16379-16392. [PMID: 31219653 DOI: 10.1002/jcb.29140] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 05/07/2019] [Indexed: 12/26/2022]
Abstract
Genome engineering technology is of great interest for biomedical research that enables scientists to make specific manipulation in the DNA sequence. Early methods for introducing double-stranded DNA breaks relies on protein-based systems. These platforms have enabled fascinating advances, but all are costly and time-consuming to engineer, preventing these from gaining high-throughput applications. The CRISPR-Cas9 system, co-opted from bacteria, has generated considerable excitement in gene targeting. In this review, we describe gene targeting techniques with an emphasis on recent strategies to improve the specificities of CRISPR-Cas systems for nuclease and non-nuclease applications.
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Affiliation(s)
- Vahideh Ahmadzadeh
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Safar Farajnia
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Roghayyeh Baghban
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Leila Rahbarnia
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Habib Zarredar
- Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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218
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Ishiguro S, Mori H, Yachie N. DNA event recorders send past information of cells to the time of observation. Curr Opin Chem Biol 2019; 52:54-62. [PMID: 31200335 DOI: 10.1016/j.cbpa.2019.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/26/2019] [Accepted: 05/10/2019] [Indexed: 11/17/2022]
Abstract
While current omics and single cell technologies have enabled measurements of high-resolution molecular snapshots of cells at a large scale, these technologies all require destruction of samples and prevent us from analyzing dynamic changes in molecular profiles, phenotypes, and behaviors of individual cells in a complex system. One possible direction to overcome this issue is the development of a cell-embedded 'event recorder' system, whereby molecular and phenotypic information of a cell(s) can be obtained at the time of observation with their past event information stored in 'heritable polymers' of the same cell. This concept has been demonstrated by many synthetic cellular circuits that monitor and transmit a certain set of environmental and intracellular signals into DNA, and have now been further accelerated by recent CRISPR-related technologies. Notably, the discovery of the RT-Cas1-Cas2 system, which acquires sequences of cellular transcripts into a specific host genomic region, has enabled recording of a broader range of molecular profile histories in the DNA tapes of cells, to understand the dynamics of complex biological processes that cannot be addressed by current technologies.
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Affiliation(s)
- Soh Ishiguro
- Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan; Institute for Advanced Biosciences, Keio University, Tsuruoka 997-0035, Japan; Graduate School of Media and Governance, Keio University, Fujisawa 252-0882, Japan
| | - Hideto Mori
- Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan; Institute for Advanced Biosciences, Keio University, Tsuruoka 997-0035, Japan; Graduate School of Media and Governance, Keio University, Fujisawa 252-0882, Japan
| | - Nozomu Yachie
- Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan; Institute for Advanced Biosciences, Keio University, Tsuruoka 997-0035, Japan; Graduate School of Media and Governance, Keio University, Fujisawa 252-0882, Japan; Department of Biological Sciences, School of Science, The University of Tokyo, Tokyo 113-0033, Japan; PRESTO, Japan Science and Technology Agency (JST), Tokyo 153-8904, Japan.
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219
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Shen S, Zhang X, Li Z. Development of an engineered carbamoyl phosphate synthetase with released sensitivity to feedback inhibition by site-directed mutation and casting error-prone PCR. Enzyme Microb Technol 2019; 129:109354. [PMID: 31307577 DOI: 10.1016/j.enzmictec.2019.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/30/2019] [Accepted: 05/26/2019] [Indexed: 12/26/2022]
Abstract
Carbamoyl phosphate synthetase (CPS) is a key enzyme in both pyrimidine and arginine biosynthesis. However, it is inhibited strongly by uridine monophosphate (UMP), which is an intermediate of the de-novo synthesis of pyrimidine nucleoside. In this study, the native carbamoyl phosphate synthetase, from Escherichia coli, was evolved by site-directed mutation and casting error-prone PCR. Compared with the wild-type, the variant N1015 F had released sensitivity to UMP and exhibited 100% of the initial activity in the presence of UMP. Variant K1006A exhibited 0.14-fold improvement in initial activity and kept above 65% of relative activity under the saturated concentration of inhibitor. Structure analysis of variants demonstrated that the reduced sensitivity to inhibitor was largely attributed to the decreased hydrogen bonds, which could reduce the binding affinity with UMP. Also, Phe with large side chain could narrow the binding pocket and generate more steric hindrance. Based on the results in this study, N1015F was an ideal alternative catalyst for the wild-type CPS for pyrimidine biosynthesis.
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Affiliation(s)
- Su Shen
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Xing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Zhimin Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China; Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai 200237, China.
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220
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Huang TP, Zhao KT, Miller SM, Gaudelli NM, Oakes BL, Fellmann C, Savage DF, Liu DR. Circularly permuted and PAM-modified Cas9 variants broaden the targeting scope of base editors. Nat Biotechnol 2019; 37:626-631. [PMID: 31110355 PMCID: PMC6551276 DOI: 10.1038/s41587-019-0134-y] [Citation(s) in RCA: 174] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 04/11/2019] [Indexed: 12/12/2022]
Abstract
Base editing requires that the target sequence satisfy the protospacer adjacent motif requirement of the Cas9 domain and that the target nucleotide be located within the editing window of the base editor. To increase the targeting scope of base editors, we engineered six optimized adenine base editors (ABEmax variants) that use SpCas9 variants compatible with non-NGG protospacer adjacent motifs. To increase the range of target bases that can be modified within the protospacer, we use circularly permuted Cas9 variants to produce four cytosine and four adenine base editors with an editing window expanded from ~4-5 nucleotides to up to ~8-9 nucleotides and reduced byproduct formation. This set of base editors improves the targeting scope of cytosine and adenine base editing.
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Affiliation(s)
- Tony P Huang
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Kevin T Zhao
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Shannon M Miller
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Nicole M Gaudelli
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Benjamin L Oakes
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Christof Fellmann
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - David F Savage
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA.
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221
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Abstract
PURPOSE OF REVIEW The purpose is to review recent progress in applying the CRISPR/Cas9 system to lipid metabolism and therapeutics. RECENT FINDINGS The CRISPR/Cas9 system has been used to generate knockout animals for lipid genes in multiple species. Somatic genome editing with CRISPR/Cas9 can efficiently disrupt genes in adult animals, including a new strategy for generating atherosclerosis. Refinements to the CRISPR/Cas9 system including epigenetic modulators and base editors offer new avenues to manipulate gene expression. The recent report of germline genome editing in humans highlights the promise as well as perils of this technology. SUMMARY CRISPR/Cas9 is a transformative technology that will help advance on our understanding of lipid metabolism and physiology. Somatic genome editing is a particularly promising approach for editing genes in tissues of live organisms, and represents a new means of addressing unmet therapeutic challenges in humans. Educational outreach, public debate, and consideration of ethics and safety must guide the use of genome editing in humans.
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Affiliation(s)
- Mia Furgurson
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA
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222
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Tang J, Lee T, Sun T. Single-nucleotide editing: From principle, optimization to application. Hum Mutat 2019; 40:2171-2183. [PMID: 31131955 DOI: 10.1002/humu.23819] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/30/2019] [Accepted: 05/23/2019] [Indexed: 12/26/2022]
Abstract
Cytosine base editors (CBEs) and adenine base editors (ABEs), which are generally composed of an engineered deaminase and a catalytically impaired CRISPR-Cas9 variant, are new favorite tools for single base substitution in cells and organisms. In this review, we summarize the principle of base-editing systems and elaborate on the evolution of different platforms of CBEs and ABEs, including their deaminase, Cas9 variants, and editing outcomes. Moreover, we highlight their applications in mouse and human cells and discuss the challenges and prospects of base editors. The ABE- and CBE systems have been used in gene silencing, pathogenic gene correction, and functional genetic screening. Single base editing is becoming a new promising genetic tool in biomedical research and gene therapy.
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Affiliation(s)
- Jinling Tang
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, Xiamen, Fujian, China
| | - Trevor Lee
- Department of Cell and Developmental Biology, Weill Medical College, Cornell University, New York, New York
| | - Tao Sun
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, Xiamen, Fujian, China
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223
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Mention K, Santos L, Harrison PT. Gene and Base Editing as a Therapeutic Option for Cystic Fibrosis-Learning from Other Diseases. Genes (Basel) 2019; 10:E387. [PMID: 31117296 PMCID: PMC6562706 DOI: 10.3390/genes10050387] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/11/2019] [Accepted: 05/15/2019] [Indexed: 12/21/2022] Open
Abstract
Cystic fibrosis (CF) is a monogenic autosomal recessive disorder caused by mutations in the CFTR gene. There are at least 346 disease-causing variants in the CFTR gene, but effective small-molecule therapies exist for only ~10% of them. One option to treat all mutations is CFTR cDNA-based therapy, but clinical trials to date have only been able to stabilise rather than improve lung function disease in patients. While cDNA-based therapy is already a clinical reality for a number of diseases, some animal studies have clearly established that precision genome editing can be significantly more effective than cDNA addition. These observations have led to a number of gene-editing clinical trials for a small number of such genetic disorders. To date, gene-editing strategies to correct CFTR mutations have been conducted exclusively in cell models, with no in vivo gene-editing studies yet described. Here, we highlight some of the key breakthroughs in in vivo and ex vivo gene and base editing in animal models for other diseases and discuss what might be learned from these studies in the development of editing strategies that may be applied to cystic fibrosis as a potential therapeutic approach. There are many hurdles that need to be overcome, including the in vivo delivery of editing machinery or successful engraftment of ex vivo-edited cells, as well as minimising potential off-target effects. However, a successful proof-of-concept study for gene or base editing in one or more of the available CF animal models could pave the way towards a long-term therapeutic strategy for this disease.
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Affiliation(s)
- Karen Mention
- Department of Physiology, University College Cork, Cork T12 K8AF, Ireland.
| | - Lúcia Santos
- Department of Physiology, University College Cork, Cork T12 K8AF, Ireland.
- University of Lisboa Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, 1749-016 Lisboa, Portugal.
| | - Patrick T Harrison
- Department of Physiology, University College Cork, Cork T12 K8AF, Ireland.
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224
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Therapeutic application of the CRISPR system: current issues and new prospects. Hum Genet 2019; 138:563-590. [DOI: 10.1007/s00439-019-02028-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 05/13/2019] [Indexed: 12/23/2022]
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225
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Rees HA, Yeh WH, Liu DR. Development of hRad51-Cas9 nickase fusions that mediate HDR without double-stranded breaks. Nat Commun 2019; 10:2212. [PMID: 31101808 PMCID: PMC6525190 DOI: 10.1038/s41467-019-09983-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/04/2019] [Indexed: 12/20/2022] Open
Abstract
In mammalian cells, double-stranded DNA breaks (DSBs) are preferentially repaired through end-joining processes that generally lead to mixtures of insertions and deletions (indels) or other rearrangements at the cleavage site. In the presence of homologous DNA, homology-directed repair (HDR) can generate specific mutations, albeit typically with modest efficiency and a low ratio of HDR products:indels. Here, we develop hRad51 mutants fused to Cas9(D10A) nickase (RDN) that mediate HDR while minimizing indels. We use RDN to install disease-associated point mutations in HEK293T cells with comparable or better efficiency than Cas9 nuclease and a 2.7-to-53-fold higher ratio of desired HDR product:undesired byproducts. Across five different human cell types, RDN variants generally result in higher HDR:indel ratios and lower off-target activity than Cas9 nuclease, although HDR efficiencies remain strongly site- and cell type-dependent. RDN variants provide precision editing options in cell types amenable to HDR, especially when byproducts of DSBs must be minimized.
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Affiliation(s)
- Holly A Rees
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Wei-Hsi Yeh
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA, 02115, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02142, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
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226
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Tan ZL, Zheng X, Wu Y, Jian X, Xing X, Zhang C. In vivo continuous evolution of metabolic pathways for chemical production. Microb Cell Fact 2019; 18:82. [PMID: 31088458 PMCID: PMC6518619 DOI: 10.1186/s12934-019-1132-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/04/2019] [Indexed: 01/07/2023] Open
Abstract
Microorganisms have long been used as chemical plant to convert simple substrates into complex molecules. Various metabolic pathways have been optimised over the past few decades, but the progresses were limited due to our finite knowledge on metabolism. Evolution is a knowledge-free genetic randomisation approach, employed to improve the chemical production in microbial cell factories. However, evolution of large, complex pathway was a great challenge. The invention of continuous culturing systems and in vivo genetic diversification technologies have changed the way how laboratory evolution is conducted, render optimisation of large, complex pathway possible. In vivo genetic diversification, phenotypic selection, and continuous cultivation are the key elements in in vivo continuous evolution, where any human intervention in the process is prohibited. This approach is crucial in highly efficient evolution strategy of metabolic pathway evolution.
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Affiliation(s)
- Zheng Lin Tan
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama City, Kanagawa Prefecture, 226-8503 Japan
- Laboratory of Future Interdisciplinary Research and Science Technology, Tokyo Institute of Technology, Yokohama City, Kanagawa Prefecture, 226-8503 Japan
| | - Xiang Zheng
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
| | - Yinan Wu
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
| | - Xingjin Jian
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
| | - Xinhui Xing
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
- Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084 China
| | - Chong Zhang
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 China
- Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084 China
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227
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Safari F, Zare K, Negahdaripour M, Barekati-Mowahed M, Ghasemi Y. CRISPR Cpf1 proteins: structure, function and implications for genome editing. Cell Biosci 2019; 9:36. [PMID: 31086658 PMCID: PMC6507119 DOI: 10.1186/s13578-019-0298-7] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/20/2019] [Indexed: 12/19/2022] Open
Abstract
CRISPR and CRISPR-associated (Cas) protein, as components of microbial adaptive immune system, allows biologists to edit genomic DNA in a precise and specific way. CRISPR-Cas systems are classified into two main classes and six types. Cpf1 is a putative type V (class II) CRISPR effector, which can be programmed with a CRISPR RNA to bind and cleave complementary DNA targets. Cpf1 has recently emerged as an alternative for Cas9, due to its distinct features such as the ability to target T-rich motifs, no need for trans-activating crRNA, inducing a staggered double-strand break and potential for both RNA processing and DNA nuclease activity. In this review, we attempt to discuss the evolutionary origins, basic architectures, and molecular mechanisms of Cpf1 family proteins, as well as crRNA designing and delivery strategies. We will also describe the novel Cpf1 variants, which have broadened the versatility and feasibility of this system in genome editing, transcription regulation, epigenetic modulation, and base editing. Finally, we will be reviewing the recent studies on utilization of Cpf1as a molecular tool for genome editing.
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Affiliation(s)
- Fatemeh Safari
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Khadijeh Zare
- Department of Basic Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Manica Negahdaripour
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mazyar Barekati-Mowahed
- Department of Physiology & Biophysics, School of Medicine, Case Western Reserve University, Ohio, USA
| | - Younes Ghasemi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
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228
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Chen M, Chen L, Zeng AP. CRISPR/Cas9-facilitated engineering with growth-coupled and sensor-guided in vivo screening of enzyme variants for a more efficient chorismate pathway in E. coli. Metab Eng Commun 2019; 9:e00094. [PMID: 31193188 PMCID: PMC6520568 DOI: 10.1016/j.mec.2019.e00094] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/01/2019] [Accepted: 05/01/2019] [Indexed: 01/24/2023] Open
Abstract
Protein engineering plays an increasingly important role in developing new and optimizing existing metabolic pathways for biosynthesis. Conventional screening approach of libraries of gene and enzyme variants is often done using a host strain under conditions not relevant to the cultivation or intracellular conditions of the later production strain. This does not necessarily result in the identification of the best enzyme variant for in vivo use in the production strain. In this work, we propose a method which integrates CRISPR/Cas9-facilitated engineering of the target gene(s) with growth-coupled and sensor-guided in vivo screening (CGSS) for protein engineering and pathway optimization. The efficiency of the method is demonstrated for engineering 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase AroG, a key enzyme in the chorismate pathway for the synthesis of aromatic amino acids (AAAs), to obtain variants of AroG (AroGfbr) with increased resistance to feedback inhibition of Phe. Starting from a tryptophan (Trp)-producing E. coli strain (harboring a reported Phe-resistant AroG variant AroGS180F), the removal of all the endogenous DAHP synthases makes the growth of this strain dependent on the activity of an introduced AroG variant. The different catalytic efficiencies of AroG variants lead to different intracellular concentration of Trp which is sensed by a Trp biosensor (TnaC-eGFP). Using the growth rate and the signal strength of the biosensor as criteria, we successfully identified several novel Phe-resistant AroG variants (including the best one AroGD6G−D7A) which exhibited higher specific enzyme activity than that of the reference variant AroGS180F at the presence of 40 mM Phe. The replacement of AroGS180F with the newly identified AroGD6G−D7A in the Trp-producing strain significantly improved the Trp production by 38.5% (24.03 ± 1.02 g/L at 36 h) in a simple fed-batch fermentation. A novel approach for phenotype-focused and product-targeted in vivo screening of enzyme variants. AroG variant with high resistance to feedback inhibition of phenylalanine. Tryptophan production in E. coli improved by 38.5% with the new variant AroGD6G−D7A.
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Affiliation(s)
- Minliang Chen
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, D-21073, Hamburg, Germany
| | - Lin Chen
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, D-21073, Hamburg, Germany
| | - An-Ping Zeng
- Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, D-21073, Hamburg, Germany.,Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, North Third Ring Road 15, 100029, Beijing, China
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229
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Maji B, Gangopadhyay SA, Lee M, Shi M, Wu P, Heler R, Mok B, Lim D, Siriwardena SU, Paul B, Dančík V, Vetere A, Mesleh MF, Marraffini LA, Liu DR, Clemons PA, Wagner BK, Choudhary A. A High-Throughput Platform to Identify Small-Molecule Inhibitors of CRISPR-Cas9. Cell 2019; 177:1067-1079.e19. [PMID: 31051099 PMCID: PMC7182439 DOI: 10.1016/j.cell.2019.04.009] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 09/17/2018] [Accepted: 04/03/2019] [Indexed: 12/26/2022]
Abstract
The precise control of CRISPR-Cas9 activity is required for a number of genome engineering technologies. Here, we report a generalizable platform that provided the first synthetic small-molecule inhibitors of Streptococcus pyogenes Cas9 (SpCas9) that weigh <500 Da and are cell permeable, reversible, and stable under physiological conditions. We developed a suite of high-throughput assays for SpCas9 functions, including a primary screening assay for SpCas9 binding to the protospacer adjacent motif, and used these assays to screen a structurally diverse collection of natural-product-like small molecules to ultimately identify compounds that disrupt the SpCas9-DNA interaction. Using these synthetic anti-CRISPR small molecules, we demonstrated dose and temporal control of SpCas9 and catalytically impaired SpCas9 technologies, including transcription activation, and identified a pharmacophore for SpCas9 inhibition using structure-activity relationships. These studies establish a platform for rapidly identifying synthetic, miniature, cell-permeable, and reversible inhibitors against both SpCas9 and next-generation CRISPR-associated nucleases.
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Affiliation(s)
- Basudeb Maji
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Soumyashree A Gangopadhyay
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Miseon Lee
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Mengchao Shi
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Peng Wu
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Robert Heler
- Laboratory of Bacteriology, The Rockefeller University, New York, NY 10065, USA
| | - Beverly Mok
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Donghyun Lim
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Sachini U Siriwardena
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Bishwajit Paul
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Vlado Dančík
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Amedeo Vetere
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Michael F Mesleh
- Center for the Development of Therapeutics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 11231, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA; Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
| | - Paul A Clemons
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Bridget K Wagner
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Amit Choudhary
- Chemical Biology and Therapeutics Science Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Rees HA, Wilson C, Doman JL, Liu DR. Analysis and minimization of cellular RNA editing by DNA adenine base editors. SCIENCE ADVANCES 2019; 5:eaax5717. [PMID: 31086823 PMCID: PMC6506237 DOI: 10.1126/sciadv.aax5717] [Citation(s) in RCA: 189] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 04/16/2019] [Indexed: 05/17/2023]
Abstract
Adenine base editors (ABEs) enable precise and efficient conversion of target A•T base pairs to G•C base pairs in genomic DNA with a minimum of by-products. While ABEs have been reported to exhibit minimal off-target DNA editing, off-target editing of cellular RNA by ABEs has not been examined in depth. Here, we demonstrate that a current ABE generates low but detectable levels of widespread adenosine-to-inosine editing in cellular RNAs. Using structure-guided principles to design mutations in both deaminase domains, we developed new ABE variants that retain their ability to edit DNA efficiently but show greatly reduced RNA editing activity, as well as lower off-target DNA editing activity and reduced indel by-product formation, in three mammalian cell lines. By decoupling DNA and RNA editing activities, these ABE variants increase the precision of adenine base editing by minimizing both RNA and DNA off-target editing activity.
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Affiliation(s)
- Holly A. Rees
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Christopher Wilson
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Jordan L. Doman
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - David R. Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
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231
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Off-target challenge for base editor-mediated genome editing. Cell Biol Toxicol 2019; 35:185-187. [DOI: 10.1007/s10565-019-09474-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 04/18/2019] [Indexed: 12/21/2022]
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232
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Chen K, Wang Y, Zhang R, Zhang H, Gao C. CRISPR/Cas Genome Editing and Precision Plant Breeding in Agriculture. ANNUAL REVIEW OF PLANT BIOLOGY 2019; 70:667-697. [PMID: 30835493 DOI: 10.1146/annurev-arplant-050718-100049] [Citation(s) in RCA: 631] [Impact Index Per Article: 126.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Enhanced agricultural production through innovative breeding technology is urgently needed to increase access to nutritious foods worldwide. Recent advances in CRISPR/Cas genome editing enable efficient targeted modification in most crops, thus promising to accelerate crop improvement. Here, we review advances in CRISPR/Cas9 and its variants and examine their applications in plant genome editing and related manipulations. We highlight base-editing tools that enable targeted nucleotide substitutions and describe the various delivery systems, particularly DNA-free methods, that have linked genome editing with crop breeding. We summarize the applications of genome editing for trait improvement, development of techniques for fine-tuning gene regulation, strategies for breeding virus resistance, and the use of high-throughput mutant libraries. We outline future perspectives for genome editing in plant synthetic biology and domestication, advances in delivery systems, editing specificity, homology-directed repair, and gene drives. Finally, we discuss the challenges and opportunities for precision plant breeding and its bright future in agriculture.
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Affiliation(s)
- Kunling Chen
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China 100101;
| | - Yanpeng Wang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China 100101;
| | - Rui Zhang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China 100101;
| | - Huawei Zhang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China 100101;
| | - Caixia Gao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China 100101;
- University of Chinese Academy of Sciences, Beijing, China 100864
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233
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Satheesh V, Zhang H, Wang X, Lei M. Precise editing of plant genomes - Prospects and challenges. Semin Cell Dev Biol 2019; 96:115-123. [PMID: 31002868 DOI: 10.1016/j.semcdb.2019.04.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/26/2022]
Abstract
The past decade has witnessed unprecedented development in genome engineering, a process that enables targeted modification of genomes. The identification of sequence-specific nucleases such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and the CRISPR/Cas system, in particular, has led to precise and efficient introduction of genetic variations into genomes of various organisms. Since the CRISPR/Cas system is highly versatile, cost-effective and much superior to ZFNs and TALENs, its widespread adoption by the research community has been inevitable. In plants, a number of studies have shown that CRISPR/Cas could be a potential tool in basic research where insertion, deletion and/or substitution in the genetic sequence could help answer fundamental questions about plant processes, and in applied research these technologies could help build or reverse-engineer plant systems to make them more useful. In this review article, we summarize technologies for precise editing of genomes with a special focus on the CRISPR/Cas system, highlight the latest developments in the CRISPR/Cas system and discuss the challenges and prospects in using the system for plant biology research.
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Affiliation(s)
- Viswanathan Satheesh
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Hui Zhang
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Xianting Wang
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Mingguang Lei
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
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234
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Emerging CRISPR/Cas9 applications for T-cell gene editing. Emerg Top Life Sci 2019; 3:261-275. [PMID: 33523139 DOI: 10.1042/etls20180144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 03/04/2019] [Accepted: 03/08/2019] [Indexed: 12/17/2022]
Abstract
Gene editing tools are being rapidly developed, accelerating many areas of cell and gene therapy research. Each successive gene editing technology promises increased efficacy, improved specificity, reduced manufacturing cost and design complexity; all of which are currently epitomised by the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein (Cas9) platform. Since its conceptualisation, CRISPR-based gene editing has been applied to existing methodologies and has further allowed the exploration of novel avenues of research. Implementation of CRISPR/Cas9 has been instrumental to recent progress in the treatment of cancer, primary immunodeficiency, and infectious diseases. To this end, T-cell therapies have attempted to harness and redirect antigen recognition function, and through gene editing, broaden T-cell targeting capabilities and enhance their potency. The purpose of this review is to provide insights into emerging applications of CRISPR/Cas9 in T-cell therapies, to briefly address concerns surrounding CRISPR-mediated indel formation, and to introduce CRISPR/Cas9 base editing technologies that hold vast potential for future research and clinical translation.
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Abstract
Designer nucleases are versatile tools for genome modification and therapy development and have gained widespread accessibility with the advent of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) technology. Prokaryotic RNA-guided nucleases of CRISPR/Cas type, since first being adopted as editing tools in eukaryotic cells, have experienced rapid uptake and development. Diverse modes of delivery by viral and non-viral vectors and ongoing discovery and engineering of new CRISPR/Cas-type tools with alternative target site requirements, cleavage patterns and DNA- or RNA-specific action continue to expand the versatility of this family of nucleases. CRISPR/Cas-based molecules may also act without double-strand breaks as DNA base editors or even without single-stranded cleavage, be it as epigenetic regulators, transcription factors or RNA base editors, with further scope for discovery and development. For many potential therapeutic applications of CRISPR/Cas-type molecules and their derivatives, efficiencies still need to be improved and safety issues addressed, including those of preexisting immunity against Cas molecules, off-target activity and recombination and sequence alterations relating to double-strand-break events. This review gives a concise overview of current CRISPR/Cas tools, applications, concerns and trends.
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Affiliation(s)
- Petros Patsali
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, 6 International Airport Avenue, 1683, Nicosia, Cyprus
| | - Marina Kleanthous
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, 6 International Airport Avenue, 1683, Nicosia, Cyprus
- Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Carsten W Lederer
- Department of Molecular Genetics Thalassaemia, The Cyprus Institute of Neurology and Genetics, 6 International Airport Avenue, 1683, Nicosia, Cyprus.
- Cyprus School of Molecular Medicine, Nicosia, Cyprus.
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236
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Kim D, Kim DE, Lee G, Cho SI, Kim JS. Genome-wide target specificity of CRISPR RNA-guided adenine base editors. Nat Biotechnol 2019; 37:430-435. [PMID: 30833658 DOI: 10.1038/s41587-019-0050-1] [Citation(s) in RCA: 129] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 01/30/2019] [Indexed: 12/14/2022]
Abstract
Adenine base editors1 enable efficient targeted adenine-to-guanine single nucleotide conversions to induce or correct point mutations in human cells, animals, and plants1-4. Here we present a modified version of Digenome-seq, an in vitro method for identifying CRISPR (clustered regularly interspaced short palindromic repeats)-induced double-strand breaks using whole-genome sequencing5-8, to assess genome-wide target specificity of adenine base editors. To produce double-strand breaks at sites containing inosines, the products of adenine deamination, we treat human genomic DNA with an adenine base editor 7.10 protein-guide RNA complex and either endonuclease V or a combination of human alkyladenine DNA glycosylase and endonuclease VIII in vitro. Digenome-seq detects adenine base editor off-target sites with a substitution frequency of 0.1% or more. We show that adenine base editor 7.10, the cytosine base editor BE3, and unmodified CRISPR-associated protein 9 (Cas9) often recognize different off-target sites, highlighting the need for independent assessments of their genome-wide specificities6. Using targeted sequencing, we also show that use of preassembled adenine base editor ribonucleoproteins, modified guide RNAs5,8-11, and Sniper/Cas9 (ref. 12) reduces adenine base editor off-target activity in human cells.
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Affiliation(s)
- Daesik Kim
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul, Republic of Korea
| | - Da-Eun Kim
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul, Republic of Korea
| | - Gyeorae Lee
- Center for Genome Engineering, Institute for Basic Science, Seoul, Republic of Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon, Republic of Korea
| | - Sung-Ik Cho
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul, Republic of Korea
| | - Jin-Soo Kim
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea.
- Center for Genome Engineering, Institute for Basic Science, Seoul, Republic of Korea.
- Department of Functional Genomics, University of Science and Technology, Daejeon, Republic of Korea.
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237
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Swahn H, Harris A. Cell-Selective Regulation of CFTR Gene Expression: Relevance to Gene Editing Therapeutics. Genes (Basel) 2019; 10:E235. [PMID: 30893953 PMCID: PMC6471542 DOI: 10.3390/genes10030235] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 12/19/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) gene is an attractive target for gene editing approaches, which may yield novel therapeutic approaches for genetic diseases such as cystic fibrosis (CF). However, for gene editing to be effective, aspects of the three-dimensional (3D) structure and cis-regulatory elements governing the dynamic expression of CFTR need to be considered. In this review, we focus on the higher order chromatin organization required for normal CFTR locus function, together with the complex mechanisms controlling expression of the gene in different cell types impaired by CF pathology. Across all cells, the CFTR locus is organized into an invariant topologically associated domain (TAD) established by the architectural proteins CCCTC-binding factor (CTCF) and cohesin complex. Additional insulator elements within the TAD also recruit these factors. Although the CFTR promoter is required for basal levels of expression, cis-regulatory elements (CREs) in intergenic and intronic regions are crucial for cell-specific and temporal coordination of CFTR transcription. These CREs are recruited to the promoter through chromatin looping mechanisms and enhance cell-type-specific expression. These features of the CFTR locus should be considered when designing gene-editing approaches, since failure to recognize their importance may disrupt gene expression and reduce the efficacy of therapies.
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Affiliation(s)
- Hannah Swahn
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44067, USA.
| | - Ann Harris
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44067, USA.
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238
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Tran MTN, Khalid MKNM, Pébay A, Cook AL, Liang HH, Wong RCB, Craig JE, Liu GS, Hung SS, Hewitt AW. Screening of CRISPR/Cas base editors to target the AMD high-risk Y402H complement factor H variant. Mol Vis 2019; 25:174-182. [PMID: 30996586 PMCID: PMC6441356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 03/14/2019] [Indexed: 11/18/2022] Open
Abstract
Purpose To evaluate the efficacy of using a CRISPR/Cas-mediated strategy to correct a common high-risk allele that is associated with age-related macular degeneration (AMD; rs1061170; NM_000186.3:c.1204T>C; NP_000177.2:p.His402Tyr) in the complement factor H (CFH) gene. Methods A human embryonic kidney cell line (HEK293A) was engineered to contain the pathogenic risk variant for AMD (HEK293A-CFH). Several different base editor constructs (BE3, SaBE3, SaKKH-BE3, VQR-BE3, and Target-AID) and their respective single-guide RNA (sgRNA) expression cassettes targeting either the pathogenic risk variant allele in the CFH locus or the LacZ gene, as a negative control, were evaluated head-to-head for the incidence of a cytosine-to-thymine nucleotide correction. The base editor construct that showed appreciable editing activity was selected for further assessment in which the base-edited region was subjected to next-generation deep sequencing to quantify on-target and off-target editing efficacy. Results The tandem use of the Target-AID base editor and its respective sgRNA demonstrated a base editing efficiency of facilitating a cytosine-to-thymine nucleotide correction in 21.5% of the total sequencing reads. Additionally, the incidence of insertions and deletions (indels) was detected in only 0.15% of the sequencing reads with virtually no off-target effects evident across the top 11 predicted off-target sites containing at least one cytosine in the activity window (n = 3, pooled amplicons). Conclusions CRISPR-mediated base editing can be used to facilitate a permanent and stably inherited cytosine-to-thymine nucleotide correction of the rs1061170 SNP in the CFH gene with minimal off-target effects.
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Affiliation(s)
| | | | - Alice Pébay
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Victoria, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Victoria, Australia
- Department of Anatomy and Neuroscience, University of Melbourne, Victoria, Australia
| | - Anthony L Cook
- Wicking Dementia Research and Education Centre, University of Tasmania, Hobart, TAS 7000, Australia
| | - Helena H Liang
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Victoria, Australia
| | - Raymond C B Wong
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Victoria, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Victoria, Australia
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Bedford Park, Australia
| | - Guei-Sheung Liu
- Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Victoria, Australia
| | - Sandy S Hung
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Victoria, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Victoria, Australia
| | - Alex W Hewitt
- Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Victoria, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Victoria, Australia
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239
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Zhou S, Cai B, He C, Wang Y, Ding Q, Liu J, Liu Y, Ding Y, Zhao X, Li G, Li C, Yu H, Kou Q, Niu W, Petersen B, Sonstegard T, Ma B, Chen Y, Wang X. Programmable Base Editing of the Sheep Genome Revealed No Genome-Wide Off-Target Mutations. Front Genet 2019; 10:215. [PMID: 30930940 PMCID: PMC6428697 DOI: 10.3389/fgene.2019.00215] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 02/27/2019] [Indexed: 12/23/2022] Open
Abstract
Since its emergence, CRISPR/Cas9-mediated base editors (BEs) with cytosine deaminase activity have been used to precisely and efficiently introduce single-base mutations in genomes, including those of human cells, mice, and crop species. Most production traits in livestock are induced by point mutations, and genome editing using BEs without homology-directed repair of double-strand breaks can directly alter single nucleotides. The p.96R > C variant of Suppressor cytokine signaling 2 (SOCS2) has profound effects on body weight, body size, and milk production in sheep. In the present study, we successfully obtained lambs with defined point mutations resulting in a p.96R > C substitution in SOCS2 by the co-injection of BE3 mRNA and a single guide RNA (sgRNA) into sheep zygotes. The observed efficiency of the single nucleotide exchange in newborn animals was as high as 25%. Observations of body size and body weight in the edited group showed that gene modification contributes to enhanced growth traits in sheep. Moreover, targeted deep sequencing and unbiased family trio-based whole genome sequencing revealed undetectable off-target mutations in the edited animals. This study demonstrates the potential for the application of BE-mediated point mutations in large animals for the improvement of production traits in livestock species.
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Affiliation(s)
- Shiwei Zhou
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Bei Cai
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Chong He
- College of Information Engineering, Northwest A&F University, Yangling, China
| | - Ying Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Qiang Ding
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Jiao Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Yao Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Yige Ding
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Xiaoe Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Guanwei Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Chao Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Honghao Yu
- Guilin Medical University, Guilin, China
| | - Qifang Kou
- Ningxia Tianyuan Tan Sheep Farm, Hongsibu, China
| | - Wenzhi Niu
- Ningxia Tianyuan Tan Sheep Farm, Hongsibu, China
| | - Bjoern Petersen
- Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut, Neustadt, Germany
| | | | - Baohua Ma
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yulin Chen
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
| | - Xiaolong Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, China
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240
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Liu K, Petree C, Requena T, Varshney P, Varshney GK. Expanding the CRISPR Toolbox in Zebrafish for Studying Development and Disease. Front Cell Dev Biol 2019; 7:13. [PMID: 30886848 PMCID: PMC6409501 DOI: 10.3389/fcell.2019.00013] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 01/24/2019] [Indexed: 12/13/2022] Open
Abstract
The study of model organisms has revolutionized our understanding of the mechanisms underlying normal development, adult homeostasis, and human disease. Much of what we know about gene function in model organisms (and its application to humans) has come from gene knockouts: the ability to show analogous phenotypes upon gene inactivation in animal models. The zebrafish (Danio rerio) has become a popular model organism for many reasons, including the fact that it is amenable to various forms of genetic manipulation. The RNA-guided CRISPR/Cas9-mediated targeted mutagenesis approaches have provided powerful tools to manipulate the genome toward developing new disease models and understanding the pathophysiology of human diseases. CRISPR-based approaches are being used for the generation of both knockout and knock-in alleles, and also for applications including transcriptional modulation, epigenome editing, live imaging of the genome, and lineage tracing. Currently, substantial effort is being made to improve the specificity of Cas9, and to expand the target coverage of the Cas9 enzymes. Novel types of naturally occurring CRISPR systems [Cas12a (Cpf1); engineered variants of Cas9, such as xCas9 and SpCas9-NG], are being studied and applied to genome editing. Since the majority of pathogenic mutations are single point mutations, development of base editors to convert C:G to T:A or A:T to G:C has further strengthened the CRISPR toolbox. In this review, we provide an overview of the increasing number of novel CRISPR-based tools and approaches, including lineage tracing and base editing.
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Affiliation(s)
| | | | | | | | - Gaurav K. Varshney
- Functional and Chemical Genomics Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
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241
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Yoo KH, Hennighausen L, Shin HY. Dissecting Tissue-Specific Super-Enhancers by Integrating Genome-Wide Analyses and CRISPR/Cas9 Genome Editing. J Mammary Gland Biol Neoplasia 2019; 24:47-59. [PMID: 30291498 DOI: 10.1007/s10911-018-9417-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/01/2018] [Indexed: 12/17/2022] Open
Abstract
Recent advances in genome-wide sequencing technologies have provided researchers with unprecedented opportunities to discover the genomic structures of gene regulatory units in living organisms. In particular, the integration of ChIP-seq, RNA-seq, and DNase-seq techniques has facilitated the mapping of a new class of regulatory elements. These elements, called super-enhancers, can regulate cell-type-specific gene sets and even fine-tune gene expression regulation in response to external stimuli, and have become a hot topic in genome biology. However, there is scant genetic evidence demonstrating their unique biological relevance and the mechanisms underlying these biological functions. In this review, we describe a robust genome-wide strategy for mapping cell-type-specific enhancers or super-enhancers in the mammary genome. In this strategy, genome-wide screening of active enhancer clusters that are co-occupied by mammary-enriched transcription factors, co-factors, and active enhancer marks is used to identify bona fide mammary tissue-specific super-enhancers. The in vivo function of these super-enhancers and their associated regulatory elements may then be investigated in various ways using the advanced CRISPR/Cas9 genome-editing technology. Based on our experience targeting various mammary genomic sites using CRISPR/Cas9 in mice, we comprehensively discuss the molecular consequences of the different targeting methods, such as the number of gRNAs and the dependence on their simultaneous or sequential injections. We also mention the considerations that are essential for obtaining accurate results and shed light on recent progress that has been made in developing modified CRISPR/Cas9 genome-editing techniques. In the future, the coupling of advanced genome-wide sequencing and genome-editing technologies could provide new insights into the complex genetic regulatory networks involved in mammary-gland development.
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Affiliation(s)
- Kyung Hyun Yoo
- Department of Biological Sciences, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- BK21 Biological Science Visiting Professor, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Ha Youn Shin
- Department of Biomedical Science and Engineering, Konkuk University, Seoul, 05029, Republic of Korea.
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242
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Rui Y, Wilson DR, Green JJ. Non-Viral Delivery To Enable Genome Editing. Trends Biotechnol 2019; 37:281-293. [PMID: 30278987 PMCID: PMC6378131 DOI: 10.1016/j.tibtech.2018.08.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/27/2018] [Accepted: 08/30/2018] [Indexed: 12/27/2022]
Abstract
Genome-editing technologies such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENS), and the clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein system have revolutionized biological research. Each biotechnology consists of a DNA-binding protein that can be programmed to recognize and initiate double-strand breaks (DSBs) for site-specific gene modification. These technologies have the potential to be harnessed to cure diseases caused by aberrant gene expression. To be successful therapeutically, their functionality depends on their safe and efficient delivery into the cell nucleus. This review discusses the challenges in the delivery of genome-editing tools, and highlights recent innovations in non-viral delivery that have potential to overcome these limitations and advance the translation of genome editing towards patient care.
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Affiliation(s)
- Yuan Rui
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; These authors contributed equally
| | - David R Wilson
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Institute for Nanobiotechnology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; These authors contributed equally
| | - Jordan J Green
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Institute for Nanobiotechnology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Departments of Materials Science and Engineering and Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21231, USA; Departments of Ophthalmology, Oncology, and Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
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243
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Jin S, Zong Y, Gao Q, Zhu Z, Wang Y, Qin P, Liang C, Wang D, Qiu JL, Zhang F, Gao C. Cytosine, but not adenine, base editors induce genome-wide off-target mutations in rice. Science 2019; 364:292-295. [PMID: 30819931 DOI: 10.1126/science.aaw7166] [Citation(s) in RCA: 394] [Impact Index Per Article: 78.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 02/17/2019] [Indexed: 01/01/2023]
Abstract
Cytosine and adenine base editors (CBEs and ABEs) are promising new tools for achieving the precise genetic changes required for disease treatment and trait improvement. However, genome-wide and unbiased analyses of their off-target effects in vivo are still lacking. Our whole-genome sequencing analysis of rice plants treated with the third-generation base editor (BE3), high-fidelity BE3 (HF1-BE3), or ABE revealed that BE3 and HF1-BE3, but not ABE, induce substantial genome-wide off-target mutations, which are mostly the C→T type of single-nucleotide variants (SNVs) and appear to be enriched in genic regions. Notably, treatment of rice with BE3 or HF1-BE3 in the absence of single-guide RNA also results in the rise of genome-wide SNVs. Thus, the base-editing unit of BE3 or HF1-BE3 needs to be optimized in order to attain high fidelity.
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Affiliation(s)
- Shuai Jin
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100864, China
| | - Yuan Zong
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100864, China
| | - Qiang Gao
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Zixu Zhu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100864, China
| | - Yanpeng Wang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Peng Qin
- Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Chengzhi Liang
- University of Chinese Academy of Sciences, Beijing 100864, China.,State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China
| | - Daowen Wang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100864, China
| | - Jin-Long Qiu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Feng Zhang
- Department of Plant and Microbial Biology, Center for Plant Precision Genomics, The Microbial and Plant Genomics Institute, University of Minnesota, Minneapolis, MN 55108, USA
| | - Caixia Gao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Genome Editing, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China. .,University of Chinese Academy of Sciences, Beijing 100864, China
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244
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Loureiro A, da Silva GJ. CRISPR-Cas: Converting A Bacterial Defence Mechanism into A State-of-the-Art Genetic Manipulation Tool. Antibiotics (Basel) 2019; 8:E18. [PMID: 30823430 PMCID: PMC6466564 DOI: 10.3390/antibiotics8010018] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/14/2019] [Accepted: 02/27/2019] [Indexed: 12/12/2022] Open
Abstract
Bacteriophages are pervasive viruses that infect bacteria, relying on their genetic machinery to replicate. In order to protect themselves from this kind of invader, bacteria developed an ingenious adaptive defence system, clustered regularly interspaced short palindromic repeats (CRISPR). Researchers soon realised that a specific type of CRISPR system, CRISPR-Cas9, could be modified into a simple and efficient genetic engineering technology, with several improvements over currently used systems. This discovery set in motion a revolution in genetics, with new and improved CRISPR systems being used in plenty of in vitro and in vivo experiments in recent years. This review illustrates the mechanisms behind CRISPR-Cas systems as a means of bacterial immunity against phage invasion and how these systems were engineered to originate new genetic manipulation tools. Newfound CRISPR-Cas technologies and the up-and-coming applications of these systems on healthcare and other fields of science are also discussed.
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Affiliation(s)
- Alexandre Loureiro
- Laboratory of Microbiology, Faculty of Pharmacy, University of Coimbra, Health Sciences Campus, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal.
| | - Gabriela Jorge da Silva
- Laboratory of Microbiology, Faculty of Pharmacy, University of Coimbra, Health Sciences Campus, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal.
- Center for Neurosciences Cell Biology, University of Coimbra, 3000-548 Coimbra, Portugal.
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245
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Li Q, Seys FM, Minton NP, Yang J, Jiang Y, Jiang W, Yang S. CRISPR-Cas9 D10A nickase-assisted base editing in the solvent producer Clostridium beijerinckii. Biotechnol Bioeng 2019; 116:1475-1483. [PMID: 30739328 DOI: 10.1002/bit.26949] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/21/2019] [Accepted: 02/06/2019] [Indexed: 01/02/2023]
Abstract
Clostridium beijerinckii is a potentially important industrial microorganism as it can synthesize valuable chemicals and fuels from various carbon sources. The establishment of convenient to use, effective gene tools with which the organism can be rapidly modified is essential if its full potential is to be realized. Here, we developed a genomic editing tool (pCBEclos) for use in C. beijerinckii based on the fusion of cytidine deaminase (Apobec1), Cas9 D10A nickase and uracil DNA glycosylase inhibitor (UGI). Apobec1 and UGI are guided to the target site where they introduce specific base-pair substitutions through the conversion of C·G to T·A. By appropriate choice of target sequence, these nucleotide changes are capable of creating missense mutation or null mutations in a gene. Through optimization of pCBEclos, the system derived, pCBEclos-opt, has been used to rapidly generate four different mutants in C. beijerinckii, in pyrE, xylR, spo0A, and araR. The efficiency of the system was such that they could sometimes be directly obtained following transformation, otherwise only requiring one single restreaking step. Whilst CRISPR-Cas9 nickase systems, such as pNICKclos2.0, have previously been reported in C. beijerinckii, pCBEclos-opt does not rely on homologous recombination, a process that is intrinsically inefficient in clostridia such as C. beijerinckii. As a consequence, bulky editing templates do not need to be included in the knockout plasmids. This both reduces plasmid size and makes their construction simpler, for example, whereas the assembly of pNICKclos2.0 requires six primers for the assembly of a typical knockout plasmid, pCBEclos-opt requires just two primers. The pCBEclos-opt plasmid established here represents a powerful new tool for genome editing in C. beijerinckii, which should be readily applicable to other clostridial species.
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Affiliation(s)
- Qi Li
- College of Life Sciences, Sichuan Normal University, Chengdu, China.,Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - François M Seys
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Nigel P Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Junjie Yang
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yu Jiang
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Weihong Jiang
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Sheng Yang
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing, China
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246
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Yeap LS, Meng FL. Cis- and trans-factors affecting AID targeting and mutagenic outcomes in antibody diversification. Adv Immunol 2019; 141:51-103. [PMID: 30904133 DOI: 10.1016/bs.ai.2019.01.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Antigen receptor diversification is a hallmark of adaptive immunity which allows specificity of the receptor to particular antigen. B cell receptor (BCR) or its secreted form, antibody, is diversified through antigen-independent and antigen-dependent mechanisms. During B cell development in bone marrow, BCR is diversified via V(D)J recombination mediated by RAG endonuclease. Upon stimulation by antigen, B cell undergo somatic hypermutation (SHM) to allow affinity maturation and class switch recombination (CSR) to change the effector function of the antibody. Both SHM and CSR are initiated by activation-induced cytidine deaminase (AID). Repair of AID-initiated lesions through different DNA repair pathways results in diverse mutagenic outcomes. Here, we focus on discussing cis- and trans-factors that target AID to its substrates and factors that affect different outcomes of AID-initiated lesions. The knowledge of mechanisms that govern AID targeting and outcomes could be harnessed to elicit rare functional antibodies and develop ex vivo antibody diversification approaches with diversifying base editors.
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Affiliation(s)
- Leng-Siew Yeap
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Fei-Long Meng
- 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, University of Chinese Academy of Sciences, Shanghai, China.
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247
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Bergen DJM, Kague E, Hammond CL. Zebrafish as an Emerging Model for Osteoporosis: A Primary Testing Platform for Screening New Osteo-Active Compounds. Front Endocrinol (Lausanne) 2019; 10:6. [PMID: 30761080 PMCID: PMC6361756 DOI: 10.3389/fendo.2019.00006] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 01/09/2019] [Indexed: 12/16/2022] Open
Abstract
Osteoporosis is metabolic bone disease caused by an altered balance between bone anabolism and catabolism. This dysregulated balance is responsible for fragile bones that fracture easily after minor falls. With an aging population, the incidence is rising and as yet pharmaceutical options to restore this imbalance is limited, especially stimulating osteoblast bone-building activity. Excitingly, output from large genetic studies on people with high bone mass (HBM) cases and genome wide association studies (GWAS) on the population, yielded new insights into pathways containing osteo-anabolic players that have potential for drug target development. However, a bottleneck in development of new treatments targeting these putative osteo-anabolic genes is the lack of animal models for rapid and affordable testing to generate functional data and that simultaneously can be used as a compound testing platform. Zebrafish, a small teleost fish, are increasingly used in functional genomics and drug screening assays which resulted in new treatments in the clinic for other diseases. In this review we outline the zebrafish as a powerful model for osteoporosis research to validate potential therapeutic candidates, describe the tools and assays that can be used to study bone homeostasis, and affordable (semi-)high-throughput compound testing.
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Affiliation(s)
- Dylan J. M. Bergen
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Southmead Hospital, University of Bristol, Bristol, United Kingdom
| | - Erika Kague
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Chrissy L. Hammond
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
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248
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Tan J, Zhang F, Karcher D, Bock R. Engineering of high-precision base editors for site-specific single nucleotide replacement. Nat Commun 2019; 10:439. [PMID: 30683865 PMCID: PMC6347625 DOI: 10.1038/s41467-018-08034-8] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 12/12/2018] [Indexed: 12/17/2022] Open
Abstract
RNA-guided nucleases of the CRISPR/Cas type can be repurposed as programmable nucleotide deaminases to mediate targeted nucleotide substitutions. Such base editors have enormous potential in genome editing, gene therapy and precision breeding. However, current editors suffer from limited specificity in that they edit different and/or multiple bases within a larger sequence window. Using cytidine deaminase base editors that elicit C-to-T mutations, we show here that high editing precision can be achieved by engineering the connection between the deaminase domain and the Cas domain of the editor. By systematically testing different linker sequences and removing non-essential sequences from the deaminase, we obtain high-precision base editors with narrow activity windows that can selectively edit a single cytidine at a specific position with high accuracy and efficiency. These base editors will enable the use of genome editing in applications where single-nucleotide changes are required and off-target editing of adjacent nucleotides is not tolerable.
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Affiliation(s)
- Junjie Tan
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Fei Zhang
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, 430070, Wuhan, Hubei, China
| | - Daniel Karcher
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany.
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249
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A panel of eGFP reporters for single base editing by APOBEC-Cas9 editosome complexes. Sci Rep 2019; 9:497. [PMID: 30679582 PMCID: PMC6345908 DOI: 10.1038/s41598-018-36739-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 11/26/2018] [Indexed: 01/16/2023] Open
Abstract
The prospect of introducing a single C-to-T change at a specific genomic location has become feasible with APOBEC-Cas9 editing technologies. We present a panel of eGFP reporters for quantification and optimization of single base editing by APOBEC-Cas9 editosomes. Reporter utility is demonstrated by comparing activities of seven human APOBEC3 enzymes and rat APOBEC1 (BE3). APOBEC3A and RNA binding-defective variants of APOBEC3B and APOBEC3H display the highest single base editing efficiencies. APOBEC3B catalytic domain complexes also elicit the lowest frequencies of adjacent off-target events. However, unbiased deep-sequencing of edited reporters shows that all editosomes have some degree of local off-target editing. Thus, further optimization is required to generate true single base editors and the eGFP reporters described here have the potential to facilitate this process.
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250
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Liang P, Xie X, Zhi S, Sun H, Zhang X, Chen Y, Chen Y, Xiong Y, Ma W, Liu D, Huang J, Songyang Z. Genome-wide profiling of adenine base editor specificity by EndoV-seq. Nat Commun 2019; 10:67. [PMID: 30622278 PMCID: PMC6325126 DOI: 10.1038/s41467-018-07988-z] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 12/05/2018] [Indexed: 12/26/2022] Open
Abstract
The adenine base editor (ABE), capable of catalyzing A•T to G•C conversions, is an important gene editing toolbox. Here, we systematically evaluate genome-wide off-target deamination by ABEs using the EndoV-seq platform we developed. EndoV-seq utilizes Endonuclease V to nick the inosine-containing DNA strand of genomic DNA deaminated by ABE in vitro. The treated DNA is then whole-genome sequenced to identify off-target sites. Of the eight gRNAs we tested with ABE, 2-19 (with an average of 8.0) off-target sites are found, significantly fewer than those found for canonical Cas9 nuclease (7-320, 160.7 on average). In vivo off-target deamination is further validated through target site deep sequencing. Moreover, we demonstrated that six different ABE-gRNA complexes could be examined in a single EndoV-seq assay. Our study presents the first detection method to evaluate genome-wide off-target effects of ABE, and reveals possible similarities and differences between ABE and canonical Cas9 nuclease.
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Affiliation(s)
- Puping Liang
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
- Key Laboratory of Reproductive Medicine of Guangdong Province, School of Life Sciences and the the First Affiliated Hospital, Sun Yat-sen University, 510275, Guangzhou, China
| | - Xiaowei Xie
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 3000000, Tianjin, China
| | - Shengyao Zhi
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
| | - Hongwei Sun
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
| | - Xiya Zhang
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
| | - Yu Chen
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
| | - Yuxi Chen
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
| | - Yuanyan Xiong
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
| | - Wenbin Ma
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China
| | - Dan Liu
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, 77030, Houston, TX, USA
| | - Junjiu Huang
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China.
- Key Laboratory of Reproductive Medicine of Guangdong Province, School of Life Sciences and the the First Affiliated Hospital, Sun Yat-sen University, 510275, Guangzhou, China.
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China.
- Key Laboratory of Reproductive Medicine of Guangdong Province, the Third Affiliated Hospital of Guangzhou Medical University, 510150, Guangzhou, China.
| | - Zhou Songyang
- The First Affiliated Hospital, Sun Yat-sen University; MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, 510275, Guangzhou, China.
- Key Laboratory of Reproductive Medicine of Guangdong Province, School of Life Sciences and the the First Affiliated Hospital, Sun Yat-sen University, 510275, Guangzhou, China.
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, 77030, Houston, TX, USA.
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China.
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