1
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Zhu C, Hao Z, Liu D. Reshaping the Landscape of the Genome: Toolkits for Precise DNA Methylation Manipulation and Beyond. JACS AU 2024; 4:40-57. [PMID: 38274248 PMCID: PMC10806789 DOI: 10.1021/jacsau.3c00671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/26/2023] [Accepted: 12/01/2023] [Indexed: 01/27/2024]
Abstract
DNA methylation plays a pivotal role in various biological processes and is highly related to multiple diseases. The exact functions of DNA methylation are still puzzling due to its uneven distribution, dynamic conversion, and complex interactions with other substances. Current methods such as chemical- and enzyme-based sequencing techniques have enabled us to pinpoint DNA methylation at single-base resolution, which necessitated the manipulation of DNA methylation at comparable resolution to precisely illustrate the correlations and causal relationships between the functions of DNA methylation and its spatiotemporal patterns. Here a perspective on the past, recent process, and future of precise DNA methylation tools is provided. Specifically, genome-wide and site-specific manipulation of DNA methylation methods is discussed, with an emphasis on their principles, limitations, applications, and future developmental directions.
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Affiliation(s)
- Chenyou Zhu
- Engineering
Research Center of Advanced Rare Earth Materials, Ministry of Education,
Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Ziyang Hao
- School
of Pharmaceutical Sciences, Capital Medical
University, Beijing, 100069, PR China
| | - Dongsheng Liu
- Engineering
Research Center of Advanced Rare Earth Materials, Ministry of Education,
Department of Chemistry, Tsinghua University, Beijing 100084, China
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2
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Tompkins JD. Transgenerational Epigenetic DNA Methylation Editing and Human Disease. Biomolecules 2023; 13:1684. [PMID: 38136557 PMCID: PMC10742326 DOI: 10.3390/biom13121684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/18/2023] [Accepted: 11/20/2023] [Indexed: 12/24/2023] Open
Abstract
During gestation, maternal (F0), embryonic (F1), and migrating primordial germ cell (F2) genomes can be simultaneously exposed to environmental influences. Accumulating evidence suggests that operating epi- or above the genetic DNA sequence, covalent DNA methylation (DNAme) can be recorded onto DNA in response to environmental insults, some sites which escape normal germline erasure. These appear to intrinsically regulate future disease propensity, even transgenerationally. Thus, an organism's genome can undergo epigenetic adjustment based on environmental influences experienced by prior generations. During the earliest stages of mammalian development, the three-dimensional presentation of the genome is dramatically changed, and DNAme is removed genome wide. Why, then, do some pathological DNAme patterns appear to be heritable? Are these correctable? In the following sections, I review concepts of transgenerational epigenetics and recent work towards programming transgenerational DNAme. A framework for editing heritable DNAme and challenges are discussed, and ethics in human research is introduced.
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Affiliation(s)
- Joshua D Tompkins
- Department of Diabetes Complications and Metabolism, Arthur Riggs Diabetes and Metabolism Research Institute, City of Hope, Duarte, CA 91010, USA
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3
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Fontana L, Alahouzou Z, Miccio A, Antoniou P. Epigenetic Regulation of β-Globin Genes and the Potential to Treat Hemoglobinopathies through Epigenome Editing. Genes (Basel) 2023; 14:genes14030577. [PMID: 36980849 PMCID: PMC10048329 DOI: 10.3390/genes14030577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 02/21/2023] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
Beta-like globin gene expression is developmentally regulated during life by transcription factors, chromatin looping and epigenome modifications of the β-globin locus. Epigenome modifications, such as histone methylation/demethylation and acetylation/deacetylation and DNA methylation, are associated with up- or down-regulation of gene expression. The understanding of these mechanisms and their outcome in gene expression has paved the way to the development of new therapeutic strategies for treating various diseases, such as β-hemoglobinopathies. Histone deacetylase and DNA methyl-transferase inhibitors are currently being tested in clinical trials for hemoglobinopathies patients. However, these approaches are often uncertain, non-specific and their global effect poses serious safety concerns. Epigenome editing is a recently developed and promising tool that consists of a DNA recognition domain (zinc finger, transcription activator-like effector or dead clustered regularly interspaced short palindromic repeats Cas9) fused to the catalytic domain of a chromatin-modifying enzyme. It offers a more specific targeting of disease-related genes (e.g., the ability to reactivate the fetal γ-globin genes and improve the hemoglobinopathy phenotype) and it facilitates the development of scarless gene therapy approaches. Here, we summarize the mechanisms of epigenome regulation of the β-globin locus, and we discuss the application of epigenome editing for the treatment of hemoglobinopathies.
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Affiliation(s)
- Letizia Fontana
- Laboratory of Chromatin and Gene Regulation during Development, INSERM UMR 1163, Imagine Institute, Université Paris Cité, F-75015 Paris, France
| | - Zoe Alahouzou
- Laboratory of Chromatin and Gene Regulation during Development, INSERM UMR 1163, Imagine Institute, Université Paris Cité, F-75015 Paris, France
| | - Annarita Miccio
- Laboratory of Chromatin and Gene Regulation during Development, INSERM UMR 1163, Imagine Institute, Université Paris Cité, F-75015 Paris, France
- Correspondence: (A.M.); (P.A.)
| | - Panagiotis Antoniou
- Laboratory of Chromatin and Gene Regulation during Development, INSERM UMR 1163, Imagine Institute, Université Paris Cité, F-75015 Paris, France
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D Unit, AstraZeneca, 431 50 Gothenburg, Sweden
- Correspondence: (A.M.); (P.A.)
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4
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Lowering DNA binding affinity of SssI DNA methyltransferase does not enhance the specificity of targeted DNA methylation in E. coli. Sci Rep 2021; 11:15226. [PMID: 34315949 PMCID: PMC8316445 DOI: 10.1038/s41598-021-94528-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/12/2021] [Indexed: 11/09/2022] Open
Abstract
Targeted DNA methylation is a technique that aims to methylate cytosines in selected genomic loci. In the most widely used approach a CG-specific DNA methyltransferase (MTase) is fused to a sequence specific DNA binding protein, which binds in the vicinity of the targeted CG site(s). Although the technique has high potential for studying the role of DNA methylation in higher eukaryotes, its usefulness is hampered by insufficient methylation specificity. One of the approaches proposed to suppress methylation at unwanted sites is to use MTase variants with reduced DNA binding affinity. In this work we investigated how methylation specificity of chimeric MTases containing variants of the CG-specific prokaryotic MTase M.SssI fused to zinc finger or dCas9 targeting domains is influenced by mutations affecting catalytic activity and/or DNA binding affinity of the MTase domain. Specificity of targeted DNA methylation was assayed in E. coli harboring a plasmid with the target site. Digestions of the isolated plasmids with methylation sensitive restriction enzymes revealed that specificity of targeted DNA methylation was dependent on the activity but not on the DNA binding affinity of the MTase. These results have implications for the design of strategies of targeted DNA methylation.
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5
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Chen Z, Elowitz MB. Programmable protein circuit design. Cell 2021; 184:2284-2301. [PMID: 33848464 PMCID: PMC8087657 DOI: 10.1016/j.cell.2021.03.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 02/22/2021] [Accepted: 03/02/2021] [Indexed: 12/11/2022]
Abstract
A fundamental challenge in synthetic biology is to create molecular circuits that can program complex cellular functions. Because proteins can bind, cleave, and chemically modify one another and interface directly and rapidly with endogenous pathways, they could extend the capabilities of synthetic circuits beyond what is possible with gene regulation alone. However, the very diversity that makes proteins so powerful also complicates efforts to harness them as well-controlled synthetic circuit components. Recent work has begun to address this challenge, focusing on principles such as orthogonality and composability that permit construction of diverse circuit-level functions from a limited set of engineered protein components. These approaches are now enabling the engineering of circuits that can sense, transmit, and process information; dynamically control cellular behaviors; and enable new therapeutic strategies, establishing a powerful paradigm for programming biology.
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Affiliation(s)
- Zibo Chen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Michael B Elowitz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.
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6
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Fulk EM, Huh D, Atkinson JT, Lie M, Masiello CA, Silberg JJ. A Split Methyl Halide Transferase AND Gate That Reports by Synthesizing an Indicator Gas. ACS Synth Biol 2020; 9:3104-3113. [PMID: 33104325 DOI: 10.1021/acssynbio.0c00355] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Monitoring microbial reactions in highly opaque or autofluorescent environments like soils, seawater, and wastewater remains challenging. To develop a simple approach for observing post-translational reactions within microbes situated in environmental matrices, we designed a methyl halide transferase (MHT) fragment complementation assay that reports by synthesizing an indicator gas. We show that backbone fission within regions of high sequence variability in the Rossmann domain yields split MHT (sMHT) AND gates whose fragments cooperatively associate to synthesize CH3Br. Additionally, we identify a sMHT whose fragments require fusion to pairs of interacting partner proteins for maximal activity. We also show that sMHT fragments fused to FKBP12 and the FKBP-rapamycin binding domain of mTOR display significantly enhanced CH3Br production in the presence of rapamycin. This gas production is reversed in the presence of the competitive inhibitor of FKBP12/FKPB dimerization, indicating that sMHT is a reversible reporter of post-translational reactions. This sMHT represents the first genetic AND gate that reports on protein-protein interactions via an indicator gas. Because indicator gases can be measured in the headspaces of complex environmental samples, this assay should be useful for monitoring the dynamics of diverse molecular interactions within microbes situated in hard-to-image marine and terrestrial matrices.
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Affiliation(s)
- Emily M. Fulk
- Systems, Synthetic, and Physical Biology Graduate Program, Rice University, 6100 Main Street, MS-180, Houston, Texas 77005, United States
| | - Dongkuk Huh
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Joshua T. Atkinson
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Margaret Lie
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Caroline A. Masiello
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
- Department of Earth, Environmental and Planetary Sciences, Rice University, MS 126, Houston, Texas 77005, United States
- Department of Chemistry, Rice University, 6100 Main Street, MS-60, Houston, Texas 77005, United States
| | - Jonathan J. Silberg
- Department of Biosciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
- Department of Bioengineering, Rice University, 6100 Main Street, MS-142, Houston, Texas 77005, United States
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, Texas 77005, United States
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7
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Kirkpatrick RL, Lewis K, Langan RA, Lajoie MJ, Boyken SE, Eakman M, Baker D, Zalatan JG. Conditional Recruitment to a DNA-Bound CRISPR-Cas Complex Using a Colocalization-Dependent Protein Switch. ACS Synth Biol 2020; 9:2316-2323. [PMID: 32816470 PMCID: PMC7976376 DOI: 10.1021/acssynbio.0c00012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
To spatially control biochemical functions at specific sites within a genome, we have engineered a synthetic switch that activates when bound to its DNA target site. The system uses two CRISPR-Cas complexes to colocalize components of a de novo-designed protein switch (Co-LOCKR) to adjacent sites in the genome. Colocalization triggers a conformational change in the switch from an inactive closed state to an active open state with an exposed functional peptide. We prototype the system in yeast and demonstrate that DNA binding triggers activation of the switch, recruitment of a transcription factor, and expression of a downstream reporter gene. This DNA-triggered Co-LOCKR switch provides a platform to engineer sophisticated functions that should only be executed at a specific target site within the genome, with potential applications in a wide range of synthetic systems including epigenetic regulation, imaging, and genetic logic circuits.
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Affiliation(s)
- Robin L. Kirkpatrick
- Department of Chemistry, University of Washington, Seattle, WA, 98195, United States
- Graduate Program in Biological Physics, Structure, and Design, University of Washington, Seattle, WA, 98195, United States
| | - Kieran Lewis
- Department of Chemistry, University of Washington, Seattle, WA, 98195, United States
| | - Robert A. Langan
- Graduate Program in Biological Physics, Structure, and Design, University of Washington, Seattle, WA, 98195, United States
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, United States
- Institute for Protein Design, University of Washington, Seattle, WA, 98195, United States
| | - Marc J. Lajoie
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, United States
- Institute for Protein Design, University of Washington, Seattle, WA, 98195, United States
| | - Scott E. Boyken
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, United States
- Institute for Protein Design, University of Washington, Seattle, WA, 98195, United States
| | - Madeleine Eakman
- Department of Chemistry, University of Washington, Seattle, WA, 98195, United States
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, United States
- Institute for Protein Design, University of Washington, Seattle, WA, 98195, United States
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, United States
| | - Jesse G. Zalatan
- Department of Chemistry, University of Washington, Seattle, WA, 98195, United States
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8
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Abstract
The advent of locus-specific protein recruitment technologies has enabled a new class of studies in chromatin biology. Epigenome editors enable biochemical modifications of chromatin at almost any specific endogenous locus. Their locus specificity unlocks unique information including the functional roles of distinct modifications at specific genomic loci. Given the growing interest in using these tools for biological and translational studies, there are many specific design considerations depending on the scientific question or clinical need. Here we present and discuss important design considerations and challenges regarding the biochemical and locus specificities of epigenome editors. These include how to account for the complex biochemical diversity of chromatin; control for potential interdependency of epigenome editors and their resultant modifications; avoid sequestration effects; quantify the locus specificity of epigenome editors; and improve locus specificity by considering concentration, affinity, avidity, and sequestration effects.
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9
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Xiong T, Rohm D, Workman RE, Roundtree L, Novina CD, Timp W, Ostermeier M. Protein engineering strategies for improving the selective methylation of target CpG sites by a dCas9-directed cytosine methyltransferase in bacteria. PLoS One 2018; 13:e0209408. [PMID: 30562388 PMCID: PMC6298699 DOI: 10.1371/journal.pone.0209408] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 12/05/2018] [Indexed: 12/22/2022] Open
Abstract
Mammalian gene expression is a complex process regulated in part by CpG methylation. The ability to target methylation for de novo gene regulation could have therapeutic and research applications. We have previously developed a dCas9-MC/MN protein for targeting CpG methylation. dCas9-MC/MN is composed of an artificially split M.SssI methyltransferase (MC/MN), with the MC fragment fused to a nuclease-null CRISPR/Cas9 (dCas9). Guide RNAs directed dCas9-MC/MN to methylate target sites in E. coli and human cells but also caused some low-level off-target methylation. Here, in E. coli, we show that shortening the dCas9-MC linker increases methylation of CpG sites located at select distances from the dCas9 binding site. Although a shortened linker decreased methylation of other CpGs proximal to the target site, it did not reduce off-target methylation of more distant CpG sites. Instead, targeted mutagenesis of the methyltransferase's DNA binding domain, designed to reduce DNA affinity, significantly and preferentially reduced methylation of such sites.
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Affiliation(s)
- Tina Xiong
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Dahlia Rohm
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Rachael E. Workman
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Lauren Roundtree
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Carl D. Novina
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, United States of America
| | - Winston Timp
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Marc Ostermeier
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
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10
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Dual column approach for the purification of zinc finger proteins by immobilized metal affinity chromatography. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.08.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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11
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Albert P, Varga B, Zsibrita N, Kiss A. Circularly permuted variants of two CG-specific prokaryotic DNA methyltransferases. PLoS One 2018; 13:e0197232. [PMID: 29746549 PMCID: PMC5944983 DOI: 10.1371/journal.pone.0197232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/27/2018] [Indexed: 01/06/2023] Open
Abstract
The highly similar prokaryotic DNA (cytosine-5) methyltransferases (C5-MTases) M.MpeI and M.SssI share the specificity of eukaryotic C5-MTases (5'-CG), and can be useful research tools in the study of eukaryotic DNA methylation and epigenetic regulation. In an effort to improve the stability and solubility of complementing fragments of the two MTases, genes encoding circularly permuted (CP) variants of M.MpeI and M.SssI were created, and cloned in a plasmid vector downstream of an arabinose-inducible promoter. MTase activity of the CP variants was tested by digestion of the plasmids with methylation-sensitive restriction enzymes. Eleven of the fourteen M.MpeI permutants and six of the seven M.SssI permutants had detectable MTase activity as indicated by the full or partial protection of the plasmid carrying the cpMTase gene. Permutants cp62M.MpeI and cp58M.SssI, in which the new N-termini are located between conserved motifs II and III, had by far the highest activity. The activity of cp62M.MpeI was comparable to the activity of wild-type M.MpeI. Based on the location of the split sites, the permutants possessing MTase activity can be classified in ten types. Although most permutation sites were designed to fall outside of conserved motifs, and the MTase activity of the permutants measured in cell extracts was in most cases substantially lower than that of the wild-type enzyme, the high proportion of circular permutation topologies compatible with MTase activity is remarkable, and is a new evidence for the structural plasticity of C5-MTases. A computer search of the REBASE database identified putative C5-MTases with CP arrangement. Interestingly, all natural circularly permuted C5-MTases appear to represent only one of the ten types of permutation topology created in this work.
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Affiliation(s)
- Pál Albert
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
- Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Bence Varga
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Nikolett Zsibrita
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
- Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Antal Kiss
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
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12
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Waryah CB, Moses C, Arooj M, Blancafort P. Zinc Fingers, TALEs, and CRISPR Systems: A Comparison of Tools for Epigenome Editing. Methods Mol Biol 2018. [PMID: 29524128 DOI: 10.1007/978-1-4939-7774-1_2] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The completion of genome, epigenome, and transcriptome mapping in multiple cell types has created a demand for precision biomolecular tools that allow researchers to functionally manipulate DNA, reconfigure chromatin structure, and ultimately reshape gene expression patterns. Epigenetic editing tools provide the ability to interrogate the relationship between epigenetic modifications and gene expression. Importantly, this information can be exploited to reprogram cell fate for both basic research and therapeutic applications. Three different molecular platforms for epigenetic editing have been developed: zinc finger proteins (ZFs), transcription activator-like effectors (TALEs), and the system of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated (Cas) proteins. These platforms serve as custom DNA-binding domains (DBDs), which are fused to epigenetic modifying domains to manipulate epigenetic marks at specific sites in the genome. The addition and/or removal of epigenetic modifications reconfigures local chromatin structure, with the potential to provoke long-lasting changes in gene transcription. Here we summarize the molecular structure and mechanism of action of ZF, TALE, and CRISPR platforms and describe their applications for the locus-specific manipulation of the epigenome. The advantages and disadvantages of each platform will be discussed with regard to genomic specificity, potency in regulating gene expression, and reprogramming cell phenotypes, as well as ease of design, construction, and delivery. Finally, we outline potential applications for these tools in molecular biology and biomedicine and identify possible barriers to their future clinical implementation.
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Affiliation(s)
- Charlene Babra Waryah
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia
| | - Colette Moses
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia
- School of Human Sciences, The University of Western Australia, Perth, WA, Australia
| | - Mahira Arooj
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia
- School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
| | - Pilar Blancafort
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Nedlands, Perth, WA, Australia.
- School of Human Sciences, The University of Western Australia, Perth, WA, Australia.
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13
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Malankhanova TB, Malakhova AA, Medvedev SP, Zakian SM. Modern Genome Editing Technologies in Huntington's Disease Research. J Huntingtons Dis 2017; 6:19-31. [PMID: 28128770 PMCID: PMC5389024 DOI: 10.3233/jhd-160222] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The development of new revolutionary technologies for directed gene editing has made it possible to thoroughly model and study NgAgo human diseases at the cellular and molecular levels. Gene editing tools like ZFN, TALEN, CRISPR-based systems, NgAgo and SGN can introduce different modifications. In gene sequences and regulate gene expression in different types of cells including induced pluripotent stem cells (iPSCs). These tools can be successfully used for Huntington's disease (HD) modeling, for example, to generate isogenic cell lines bearing different numbers of CAG repeats or to correct the mutation causing the disease. This review presents common genome editing technologies and summarizes the progress made in using them in HD and other hereditary diseases. Furthermore, we will discuss prospects and limitations of genome editing in understanding HD pathology.
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Affiliation(s)
- Tuyana B Malankhanova
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.,Novosibirsk State University, Novosibirsk, Russia.,State Research Institute of Circulation Pathology, Ministry of Healthcare of the Russian Federation, Novosibirsk, Russia.,Institute of Chemical Biology and Fundamental Medicine, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Anastasia A Malakhova
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.,State Research Institute of Circulation Pathology, Ministry of Healthcare of the Russian Federation, Novosibirsk, Russia.,Institute of Chemical Biology and Fundamental Medicine, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Sergey P Medvedev
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.,Novosibirsk State University, Novosibirsk, Russia.,State Research Institute of Circulation Pathology, Ministry of Healthcare of the Russian Federation, Novosibirsk, Russia.,Institute of Chemical Biology and Fundamental Medicine, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Suren M Zakian
- The Federal Research Center Institute of Cytology and Genetics, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.,Novosibirsk State University, Novosibirsk, Russia.,State Research Institute of Circulation Pathology, Ministry of Healthcare of the Russian Federation, Novosibirsk, Russia.,Institute of Chemical Biology and Fundamental Medicine, The Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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14
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Xiong T, Meister GE, Workman RE, Kato NC, Spellberg MJ, Turker F, Timp W, Ostermeier M, Novina CD. Targeted DNA methylation in human cells using engineered dCas9-methyltransferases. Sci Rep 2017; 7:6732. [PMID: 28751638 PMCID: PMC5532369 DOI: 10.1038/s41598-017-06757-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 06/28/2017] [Indexed: 12/22/2022] Open
Abstract
Mammalian genomes exhibit complex patterns of gene expression regulated, in part, by DNA methylation. The advent of engineered DNA methyltransferases (MTases) to target DNA methylation to specific sites in the genome will accelerate many areas of biological research. However, targeted MTases require clear design rules to direct site-specific DNA methylation and minimize the unintended effects of off-target DNA methylation. Here we report a targeted MTase composed of an artificially split CpG MTase (sMTase) with one fragment fused to a catalytically-inactive Cas9 (dCas9) that directs the functional assembly of sMTase fragments at the targeted CpG site. We precisely map RNA-programmed DNA methylation to targeted CpG sites as a function of distance and orientation from the protospacer adjacent motif (PAM). Expression of the dCas9-sMTase in mammalian cells led to predictable and efficient (up to ~70%) DNA methylation at targeted sites. Multiplexing sgRNAs enabled targeting methylation to multiple sites in a single promoter and to multiple sites in multiple promoters. This programmable de novo MTase tool might be used for studying mechanisms of initiation, spreading and inheritance of DNA methylation, and for therapeutic gene silencing.
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Affiliation(s)
- Tina Xiong
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Glenna E Meister
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, 02141, USA
| | - Rachael E Workman
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Nathaniel C Kato
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Michael J Spellberg
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, 02141, USA
| | - Fulya Turker
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, 02141, USA
- Boston University, Boston, MA, 02215, USA
| | - Winston Timp
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Marc Ostermeier
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - Carl D Novina
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA.
- Broad Institute of Harvard and MIT, Cambridge, MA, 02141, USA.
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15
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Yamazaki T, Hatano Y, Handa T, Kato S, Hoida K, Yamamura R, Fukuyama T, Uematsu T, Kobayashi N, Kimura H, Yamagata K. Targeted DNA methylation in pericentromeres with genome editing-based artificial DNA methyltransferase. PLoS One 2017; 12:e0177764. [PMID: 28542388 PMCID: PMC5436701 DOI: 10.1371/journal.pone.0177764] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 05/03/2017] [Indexed: 01/10/2023] Open
Abstract
To study the impact of epigenetic changes on biological functions, the ability to manipulate the epigenetic status of certain genomic regions artificially could be an indispensable technology. “Epigenome editing” techniques have gradually emerged that apply TALE or CRISPR/Cas9 technologies with various effector domains isolated from epigenetic code writers or erasers such as DNA methyltransferase, 5-methylcytosine oxidase, and histone modification enzymes. Here we demonstrate that a TALE recognizing a major satellite, consisting of a repeated sequence in pericentromeres, could be fused with the bacterial CpG methyltransferase, SssI. ChIP-qPCR assays demonstrated that the fusion protein TALMaj-SssI preferentially bound to major chromosomal satellites in cultured cell lines. Then, TALMaj-SssI was expressed in fertilized mouse oocytes with hypomethylated major satellites (10–20% CpG islands). Bisulfite sequencing revealed that the DNA methylation status was increased specifically in major satellites (50–60%), but not in minor satellites or other repeat elements, such as Intracisternal A-particle (IAP) or long interspersed nuclear elements-1 (Line1) when the expression level of TALMaj-SssI is optimized in the cell. At a microscopic level, distal ends of chromosomes at the first mitotic stage were dramatically highlighted by the mCherry-tagged methyl CpG binding domain of human MBD1 (mCherry-MBD-NLS). Moreover, targeted DNA methylation to major satellites did not interfere with kinetochore function during early embryonic cleavages. Co-injection of dCas9 fused with SssI and guide RNA (gRNA) recognizing major satellite sequences enabled increment of the DNA methylation in the satellites, but a few off-target effects were also observed in minor satellites and retrotransposons. Although CRISPR can be applied instead of the TALE system, technical improvements to reduce off-target effects are required. We have demonstrated a new method of introducing DNA methylation without the need of other binding partners using the CpG methyltransferase, SssI.
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Affiliation(s)
- Taiga Yamazaki
- Division of Biomedical Research, Kitasato University Medical Center, Kitasato University, Kitamoto, Saitama, Japan
- * E-mail: (TY); (KY)
| | - Yu Hatano
- Faculty of Biology-Oriented Science and Technology, KINDAI University, Kinokawa, Wakayama, Japan
| | - Tetsuya Handa
- Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
| | - Sakiko Kato
- Faculty of Biology-Oriented Science and Technology, KINDAI University, Kinokawa, Wakayama, Japan
| | - Kensuke Hoida
- Faculty of Biology-Oriented Science and Technology, KINDAI University, Kinokawa, Wakayama, Japan
| | - Rui Yamamura
- Division of Biomedical Research, Kitasato University Medical Center, Kitasato University, Kitamoto, Saitama, Japan
| | - Takashi Fukuyama
- Division of Biomedical Research, Kitasato University Medical Center, Kitasato University, Kitamoto, Saitama, Japan
| | - Takayuki Uematsu
- Division of Biomedical Research, Kitasato University Medical Center, Kitasato University, Kitamoto, Saitama, Japan
| | - Noritada Kobayashi
- Division of Biomedical Research, Kitasato University Medical Center, Kitasato University, Kitamoto, Saitama, Japan
| | - Hiroshi Kimura
- Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
| | - Kazuo Yamagata
- Faculty of Biology-Oriented Science and Technology, KINDAI University, Kinokawa, Wakayama, Japan
- * E-mail: (TY); (KY)
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16
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Laufer BI, Singh SM. Strategies for precision modulation of gene expression by epigenome editing: an overview. Epigenetics Chromatin 2015; 8:34. [PMID: 26388942 PMCID: PMC4574080 DOI: 10.1186/s13072-015-0023-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 08/19/2015] [Indexed: 01/27/2023] Open
Abstract
Genome editing technology has evolved rather quickly and become accessible to most researchers. It has resulted in far reaching implications and a number of novel designer systems including epigenome editing. Epigenome editing utilizes a combination of nuclease-null genome editing systems and effector domains to modulate gene expression. In particular, Zinc Finger, Transcription-Activator-Like Effector, and CRISPR/Cas9 have emerged as modular systems that can be modified to allow for precision manipulation of epigenetic marks without altering underlying DNA sequence. This review contains a comprehensive catalog of effector domains that can be used with components of genome editing systems to achieve epigenome editing. Ultimately, the evidence-based design of epigenome editing offers a novel improvement to the limited attenuation strategies. There is much potential for editing and/or correcting gene expression in somatic cells toward a new era of functional genomics and personalized medicine.
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Affiliation(s)
- Benjamin I Laufer
- Molecular Genetics Unit, Department of Biology, University of Western Ontario, London, ON Canada
| | - Shiva M Singh
- Molecular Genetics Unit, Department of Biology, University of Western Ontario, London, ON Canada
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17
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Jurkowski TP, Ravichandran M, Stepper P. Synthetic epigenetics-towards intelligent control of epigenetic states and cell identity. Clin Epigenetics 2015; 7:18. [PMID: 25741388 PMCID: PMC4347971 DOI: 10.1186/s13148-015-0044-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 01/12/2015] [Indexed: 01/14/2023] Open
Abstract
Epigenetics is currently one of the hottest topics in basic and biomedical research. However, to date, most of the studies have been descriptive in nature, designed to investigate static distribution of various epigenetic modifications in cells. Even though tremendous amount of information has been collected, we are still far from the complete understanding of epigenetic processes, their dynamics or even their direct effects on local chromatin and we still do not comprehend whether these epigenetic states are the cause or the consequence of the transcriptional profile of the cell. In this review, we try to define the concept of synthetic epigenetics and outline the available genome targeting technologies, which are used for locus-specific editing of epigenetic signals. We report early success stories and the lessons we have learned from them, and provide a guide for their application. Finally, we discuss existing limitations of the available technologies and indicate possible areas for further development.
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Affiliation(s)
- Tomasz P Jurkowski
- Laboratory of Molecular Epigenetics, Institute of Biochemistry, Faculty of Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Mirunalini Ravichandran
- Laboratory of Molecular Epigenetics, Institute of Biochemistry, Faculty of Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Peter Stepper
- Laboratory of Molecular Epigenetics, Institute of Biochemistry, Faculty of Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
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18
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Abstract
As synthetic biology approaches are extended to diverse applications throughout medicine, biotechnology and basic biological research, there is an increasing need to engineer yeast, plant and mammalian cells. Eukaryotic genomes are regulated by the diverse biochemical and biophysical states of chromatin, which brings distinct challenges, as well as opportunities, over applications in bacteria. Recent synthetic approaches, including 'epigenome editing', have allowed the direct and functional dissection of many aspects of physiological chromatin regulation. These studies lay the foundation for biomedical and biotechnological engineering applications that could take advantage of the unique combinatorial and spatiotemporal layers of chromatin regulation to create synthetic systems of unprecedented sophistication.
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19
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Abstract
There have been considerable advances in uncovering the complex genetic mechanisms that underlie nervous system disease pathogenesis, particularly with the advent of exome and whole genome sequencing techniques. The emerging field of epigenetics is also providing further insights into these mechanisms. Here, we discuss our understanding of the interplay that exists between genetic and epigenetic mechanisms in these disorders, highlighting the nascent field of epigenetic epidemiology-which focuses on analyzing relationships between the epigenome and environmental exposures, development and aging, other health-related phenotypes, and disease states-and next-generation research tools (i.e., those leveraging synthetic and chemical biology and optogenetics) for examining precisely how epigenetic modifications at specific genomic sites affect disease processes.
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Affiliation(s)
- Irfan A. Qureshi
- />Roslyn and Leslie Goldstein Laboratory for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Institute for Brain Disorders and Neural Regeneration, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Rose F. Kennedy Center for Research on Intellectual and Developmental Disabilities, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461 USA
| | - Mark F. Mehler
- />Roslyn and Leslie Goldstein Laboratory for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Institute for Brain Disorders and Neural Regeneration, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Rose F. Kennedy Center for Research on Intellectual and Developmental Disabilities, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461 USA
- />Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Ruth L. and David S. Gottesman Stem Cell Institute, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Center for Epigenomics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- />Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY 10461 USA
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20
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Chaikind B, Ostermeier M. Directed evolution of improved zinc finger methyltransferases. PLoS One 2014; 9:e96931. [PMID: 24810747 PMCID: PMC4014571 DOI: 10.1371/journal.pone.0096931] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 04/14/2014] [Indexed: 01/09/2023] Open
Abstract
The ability to target DNA methylation toward a single, user-designated CpG site in vivo may have wide applicability for basic biological and biomedical research. A tool for targeting methylation toward single sites could be used to study the effects of individual methylation events on transcription, protein recruitment to DNA, and the dynamics of such epigenetic alterations. Although various tools for directing methylation to promoters exist, none offers the ability to localize methylation solely to a single CpG site. In our ongoing research to create such a tool, we have pursued a strategy employing artificially bifurcated DNA methyltransferases; each methyltransferase fragment is fused to zinc finger proteins with affinity for sequences flanking a targeted CpG site for methylation. We sought to improve the targeting of these enzymes by reducing the methyltransferase activity at non-targeted sites while maintaining high levels of activity at a targeted site. Here we demonstrate an in vitro directed evolution selection strategy to improve methyltransferase specificity and use it to optimize an engineered zinc finger methyltransferase derived from M.SssI. The unusual restriction enzyme McrBC is a key component of this strategy and is used to select against methyltransferases that methylate multiple sites on a plasmid. This strategy allowed us to quickly identify mutants with high levels of methylation at the target site (up to ∼80%) and nearly unobservable levels of methylation at a off-target sites (<1%), as assessed in E. coli. We also demonstrate that replacing the zinc finger domains with new zinc fingers redirects the methylation to a new target CpG site flanked by the corresponding zinc finger binding sequences.
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Affiliation(s)
- Brian Chaikind
- Chemistry-Biology Interface Graduate Program, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Marc Ostermeier
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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21
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Advances in genetic circuit design: novel biochemistries, deep part mining, and precision gene expression. Curr Opin Chem Biol 2013; 17:878-92. [DOI: 10.1016/j.cbpa.2013.10.003] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 10/03/2013] [Indexed: 01/14/2023]
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22
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Persikov AV, Rowland EF, Oakes BL, Singh M, Noyes MB. Deep sequencing of large library selections allows computational discovery of diverse sets of zinc fingers that bind common targets. Nucleic Acids Res 2013; 42:1497-508. [PMID: 24214968 PMCID: PMC3919609 DOI: 10.1093/nar/gkt1034] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Cys2His2 zinc finger (ZF) is the most frequently found sequence-specific DNA-binding domain in eukaryotic proteins. The ZF's modular protein-DNA interface has also served as a platform for genome engineering applications. Despite decades of intense study, a predictive understanding of the DNA-binding specificities of either natural or engineered ZF domains remains elusive. To help fill this gap, we developed an integrated experimental-computational approach to enrich and recover distinct groups of ZFs that bind common targets. To showcase the power of our approach, we built several large ZF libraries and demonstrated their excellent diversity. As proof of principle, we used one of these ZF libraries to select and recover thousands of ZFs that bind several 3-nt targets of interest. We were then able to computationally cluster these recovered ZFs to reveal several distinct classes of proteins, all recovered from a single selection, to bind the same target. Finally, for each target studied, we confirmed that one or more representative ZFs yield the desired specificity. In sum, the described approach enables comprehensive large-scale selection and characterization of ZF specificities and should be a great aid in furthering our understanding of the ZF domain.
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Affiliation(s)
- Anton V Persikov
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA, Department of Computer Science, Princeton University, Princeton, NJ 08544, USA and Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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23
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Stier I, Kiss A. Cytosine-to-uracil deamination by SssI DNA methyltransferase. PLoS One 2013; 8:e79003. [PMID: 24205358 PMCID: PMC3804486 DOI: 10.1371/journal.pone.0079003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/26/2013] [Indexed: 11/18/2022] Open
Abstract
The prokaryotic DNA(cytosine-5)methyltransferase M.SssI shares the specificity of eukaryotic DNA methyltransferases (CG) and is an important model and experimental tool in the study of eukaryotic DNA methylation. Previously, M.SssI was shown to be able to catalyze deamination of the target cytosine to uracil if the methyl donor S-adenosyl-methionine (SAM) was missing from the reaction. To test whether this side-activity of the enzyme can be used to distinguish between unmethylated and C5-methylated cytosines in CG dinucleotides, we re-investigated, using a sensitive genetic reversion assay, the cytosine deaminase activity of M.SssI. Confirming previous results we showed that M.SssI can deaminate cytosine to uracil in a slow reaction in the absence of SAM and that the rate of this reaction can be increased by the SAM analogue 5'-amino-5'-deoxyadenosine. We could not detect M.SssI-catalyzed deamination of C5-methylcytosine ((m5)C). We found conditions where the rate of M.SssI mediated C-to-U deamination was at least 100-fold higher than the rate of (m5)C-to-T conversion. Although this difference in reactivities suggests that the enzyme could be used to identify C5-methylated cytosines in the epigenetically important CG dinucleotides, the rate of M.SssI mediated cytosine deamination is too low to become an enzymatic alternative to the bisulfite reaction. Amino acid replacements in the presumed SAM binding pocket of M.SssI (F17S and G19D) resulted in greatly reduced methyltransferase activity. The G19D variant showed cytosine deaminase activity in E. coli, at physiological SAM concentrations. Interestingly, the C-to-U deaminase activity was also detectable in an E. coli ung (+) host proficient in uracil excision repair.
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Affiliation(s)
- Ildikó Stier
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Antal Kiss
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary
- * E-mail:
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24
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McGraw S, Shojaei Saadi HA, Robert C. Meeting the methodological challenges in molecular mapping of the embryonic epigenome. Mol Hum Reprod 2013; 19:809-27. [PMID: 23783346 DOI: 10.1093/molehr/gat046] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The past decade of life sciences research has been driven by progress in genomics. Many voices are already proclaiming the post-genomics era, in which phenomena other than sequence polymorphism influence gene expression and also explain complex phenotypes. One of these burgeoning fields is the study of the epigenome. Although the mechanisms by which chromatin structure and reorganization as well as cytosine methylation influence gene expression are not fully understood, they are being invoked to explain the now-accepted long-term impact of the environment on gene expression, which appears to be a factor in the development of numerous diseases. Such studies are particularly relevant in early embryonic development, during which waves of epigenetic reprogramming are known to have profound impacts. Since gametes and zygotes are in the process of resetting the genome in order to create embryonic stem cells that will each differentiate to create one of many specific tissue types, this phase of life is now viewed as a window of susceptibility to epigenetic reprogramming errors. Epigenetics could explain the influence of factors such as the nutritional/metabolic status of the mother or the artificial environment of assisted reproductive technologies. However, the peculiar nature of early embryos in addition to their scarcity poses numerous technological challenges that are slowly being overcome. The principal subject of this article is to review the suitability of various current and emerging technological platforms to study oocytes and early embryonic epigenome with more emphasis on studying DNA methylation. Furthermore, the constraint of samples size, inherent to the study of preimplantation embryo development, was put in perspective with the various molecular platforms described.
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Affiliation(s)
- Serge McGraw
- Department of Human Genetics, Montreal Children's Hospital Research Institute, McGill University, Montréal, QC H3Z 2Z3, Canada
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25
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Beurdeley M, Bietz F, Li J, Thomas S, Stoddard T, Juillerat A, Zhang F, Voytas DF, Duchateau P, Silva GH. Compact designer TALENs for efficient genome engineering. Nat Commun 2013; 4:1762. [PMID: 23612303 PMCID: PMC3644105 DOI: 10.1038/ncomms2782] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 03/20/2013] [Indexed: 01/29/2023] Open
Abstract
Transcription activator-like effector nucleases are readily targetable 'molecular scissors' for genome engineering applications. These artificial nucleases offer high specificity coupled with simplicity in design that results from the ability to serially chain transcription activator-like effector repeat arrays to target individual DNA bases. However, these benefits come at the cost of an appreciably large multimeric protein complex, in which DNA cleavage is governed by the nonspecific FokI nuclease domain. Here we report a significant improvement to the standard transcription activator-like effector nuclease architecture by leveraging the partially specific I-TevI catalytic domain to create a new class of monomeric, DNA-cleaving enzymes. In vivo yeast, plant and mammalian cell assays demonstrate that the half-size, single-polypeptide compact transcription activator-like effector nucleases exhibit overall activity and specificity comparable to currently available designer nucleases. In addition, we harness the catalytic mechanism of I-TevI to generate novel compact transcription activator-like effector nuclease-based nicking enzymes that display a greater than 25-fold increase in relative targeted gene correction efficacy.
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Affiliation(s)
- Marine Beurdeley
- Cellectis, Research and Development, 8 rue de la Croix Jarry, 75013 Paris, France
| | - Fabian Bietz
- Cellectis, Research and Development, 8 rue de la Croix Jarry, 75013 Paris, France
| | - Jin Li
- Cellectis Plant Sciences, 600 County Road D West Suite 8, New Brighton, Minnesota 55112, USA
| | - Severine Thomas
- Cellectis, Research and Development, 8 rue de la Croix Jarry, 75013 Paris, France
| | - Thomas Stoddard
- Cellectis Plant Sciences, 600 County Road D West Suite 8, New Brighton, Minnesota 55112, USA
| | - Alexandre Juillerat
- Cellectis, Research and Development, 8 rue de la Croix Jarry, 75013 Paris, France
| | - Feng Zhang
- Cellectis Plant Sciences, 600 County Road D West Suite 8, New Brighton, Minnesota 55112, USA
| | - Daniel F. Voytas
- Cellectis Plant Sciences, 600 County Road D West Suite 8, New Brighton, Minnesota 55112, USA
| | - Philippe Duchateau
- Cellectis, Research and Development, 8 rue de la Croix Jarry, 75013 Paris, France
| | - George H. Silva
- Cellectis, Research and Development, 8 rue de la Croix Jarry, 75013 Paris, France
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