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Kumar BKP, Beaubiat S, Yadav CB, Eshed R, Arazi T, Sherman A, Bouché N. Genome wide inherited modifications of the tomato epigenome by trans-activated bacterial CG methyltransferase. Cell Mol Life Sci 2024; 81:222. [PMID: 38767725 PMCID: PMC11106227 DOI: 10.1007/s00018-024-05255-7] [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: 12/13/2023] [Revised: 04/16/2024] [Accepted: 04/25/2024] [Indexed: 05/22/2024]
Abstract
BACKGROUND Epigenetic variation is mediated by epigenetic marks such as DNA methylation occurring in all cytosine contexts in plants. CG methylation plays a critical role in silencing transposable elements and regulating gene expression. The establishment of CG methylation occurs via the RNA-directed DNA methylation pathway and CG methylation maintenance relies on METHYLTRANSFERASE1, the homologue of the mammalian DNMT1. PURPOSE Here, we examined the capacity to stably alter the tomato genome methylome by a bacterial CG-specific M.SssI methyltransferase expressed through the LhG4/pOP transactivation system. RESULTS Methylome analysis of M.SssI expressing plants revealed that their euchromatic genome regions are specifically hypermethylated in the CG context, and so are most of their genes. However, changes in gene expression were observed only with a set of genes exhibiting a greater susceptibility to CG hypermethylation near their transcription start site. Unlike gene rich genomic regions, our analysis revealed that heterochromatic regions are slightly hypomethylated at CGs only. Notably, some M.SssI-induced hypermethylation persisted even without the methylase or transgenes, indicating inheritable epigenetic modification. CONCLUSION Collectively our findings suggest that heterologous expression of M.SssI can create new inherited epigenetic variations and changes in the methylation profiles on a genome wide scale. This open avenues for the conception of epigenetic recombinant inbred line populations with the potential to unveil agriculturally valuable tomato epialleles.
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Affiliation(s)
- Bapatla Kesava Pavan Kumar
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Derech Hamacabim 68, Rishon Lezion, Israel
- Molecular Biology, Acrannolife Genomics Private Limited, Chennai, Tamilnadu, 600035, India
| | - Sébastien Beaubiat
- INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), Université Paris-Saclay, 78000, Versailles, France
| | - Chandra Bhan Yadav
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Derech Hamacabim 68, Rishon Lezion, Israel
- Department of Genetics, Genomics, and Breeding, NIAB-EMR, East Malling, East Malling, ME19 6BJ, UK
| | - Ravit Eshed
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Derech Hamacabim 68, Rishon Lezion, Israel
| | - Tzahi Arazi
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Derech Hamacabim 68, Rishon Lezion, Israel
| | - Amir Sherman
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Derech Hamacabim 68, Rishon Lezion, Israel.
| | - Nicolas Bouché
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Derech Hamacabim 68, Rishon Lezion, Israel.
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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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3
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Ma L, Shcherbina A, Chetty S. Variations and expression features of CYP2D6 contribute to schizophrenia risk. Mol Psychiatry 2021; 26:2605-2615. [PMID: 32047265 PMCID: PMC8440189 DOI: 10.1038/s41380-020-0675-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 01/27/2020] [Accepted: 01/30/2020] [Indexed: 12/18/2022]
Abstract
Genome-wide association studies (GWAS) have successfully identified 145 loci implicated in schizophrenia (SCZ). However, the underlying mechanisms remain largely unknown. Here, we analyze 1497 RNA-seq data in combination with their genotype data and identify SNPs that are associated with expression throughout the genome by dissecting expression features to genes (eGene) and exon-exon junctions (eJunction). Then, we colocalize eGene and eJunction with SCZ GWAS using SMR and fine mapping. Multiple ChIP-seq data and DNA methylation data generated from brain were used for identifying the causal variants. Finally, we used a hypothesis-free (no SCZ risk loci considered) enrichment analysis to determine implicated pathways. We identified 171 genes and eight splicing junctions located within four genes (SNX19, ARL6IP4, APOPT1, and CYP2D6) that potentially contribute to SCZ susceptibility. Among the genes, CYP2D6 is significantly associated with SCZ SNPs in eGene and eJunction. In-depth examination of the CYP2D6 region revealed that a nonsynonymous single nucleotide variant rs16947 is strongly associated with a higher abundance of CYP2D6 exon 3 skipping junctions. While we found rs133377 and other functional SNPs in high linkage disequilibrium with rs16947 (r2 = 0.9539), histone acetylation analysis showed they are located within active transcription start sites. Furthermore, our data-driven enrichment analysis showed that CYP2D6 is significantly involved in drug metabolism of codeine, tamoxifen, and citalopram. Our study facilitates an understanding of the genetic architecture of SCZ and provides new drug targets.
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Affiliation(s)
- Liang Ma
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Anna Shcherbina
- grid.168010.e0000000419368956Department of Biomedical Informatics, Stanford University, Stanford, CA 94305 USA
| | - Sundari Chetty
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, 94305, USA. .,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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4
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Editing DNA Methylation in Mammalian Embryos. Int J Mol Sci 2020; 21:ijms21020637. [PMID: 31963664 PMCID: PMC7014263 DOI: 10.3390/ijms21020637] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 01/08/2023] Open
Abstract
DNA methylation in mammals is essential for numerous biological functions, such as ensuring chromosomal stability, genomic imprinting, and X-chromosome inactivation through transcriptional regulation. Gene knockout of DNA methyltransferases and demethylation enzymes has made significant contributions to analyzing the functions of DNA methylation in development. By applying epigenome editing, it is now possible to manipulate DNA methylation in specific genomic regions and to understand the functions of these modifications. In this review, we first describe recent DNA methylation editing technology. We then focused on changes in DNA methylation status during mammalian gametogenesis and preimplantation development, and have discussed the implications of applying this technology to early embryos.
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5
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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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6
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Abstract
DNA methylation plays important roles in determining cellular identity, disease, and environmental responses, but little is known about the mechanisms that drive methylation changes during cellular differentiation and tumorigenesis. Meanwhile, the causal relationship between DNA methylation and transcription remains incompletely understood. Recently developed targeted DNA methylation manipulation tools can address these gaps in knowledge, leading to new insights into how methylation governs gene expression. Here, we summarize technological developments in the DNA methylation editing field and discuss the remaining challenges facing current tools, as well as potential future directions.
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Affiliation(s)
- Yong Lei
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, TX, 77030, USA.,Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yung-Hsin Huang
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, TX, 77030, USA.,Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX, 77030, USA.,Program in Developmental Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Margaret A Goodell
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, TX, 77030, USA. .,Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX, 77030, USA. .,Program in Developmental Biology, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
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7
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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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8
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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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9
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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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10
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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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11
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Engineering and Directed Evolution of DNA Methyltransferases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016. [PMID: 27826849 DOI: 10.1007/978-3-319-43624-1_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
DNA methyltransferases (MTases) constitute an attractive target for protein engineering, thus opening the road to new ways of manipulating DNA in a unique and selective manner. Here, we review various aspects of MTase engineering, both methodological and conceptual, and also discuss future directions and challenges. Bacterial MTases that are part of restriction/modification (R/M) systems offer a convenient way for the selection of large gene libraries, both in vivo and in vitro. We review these selection methods, their strengths and weaknesses, and also the prospects for new selection approaches that will enable the directed evolution of mammalian DNA methyltransferases (Dnmts). We explore various properties of MTases that may be subject to engineering. These include engineering for higher stability and soluble expression (MTases, including bacterial ones, are prone to misfolding), engineering of the DNA target specificity, and engineering for the usage of S-adenosyl-L-methionine (AdoMet) analogs. Directed evolution of bacterial MTases also offers insights into how these enzymes readily evolve in nature, thus yielding MTases with a huge spectrum of DNA target specificities. Engineering for alternative cofactors, on the other hand, enables modification of DNA with various groups other than methyl and thus can be employed to map and redirect DNA epigenetic modifications.
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12
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Sadler T, Bhasin JM, Xu Y, Barnholz-Sloan J, Chen Y, Ting AH, Stylianou E. Genome-wide analysis of DNA methylation and gene expression defines molecular characteristics of Crohn's disease-associated fibrosis. Clin Epigenetics 2016; 8:30. [PMID: 26973718 PMCID: PMC4789277 DOI: 10.1186/s13148-016-0193-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/29/2016] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Fibrosis of the intestine is a common and poorly understood complication of Crohn's disease (CD) characterized by excessive deposition of extracellular matrix and accompanied by narrowing and obstruction of the gut lumen. Defining the molecular characteristics of this fibrotic disorder is a vital step in the development of specific prediction, prevention, and treatment strategies. Previous epigenetic studies indicate that alterations in DNA methylation could explain the mechanism by which mesenchymal cells adopt the requisite pro-fibrotic phenotype that promotes fibrosis progression. However, to date, genome-wide analysis of the DNA methylome of any type of human fibrosis is lacking. We employed an unbiased approach using deep sequencing to define the DNA methylome and transcriptome of purified fibrotic human intestinal fibroblasts (HIF) from the colons of patients with fibrostenotic CD. RESULTS When compared with normal fibroblasts, we found that the majority of differential DNA methylation was within introns and intergenic regions and not associated with CpG islands. Only a low percentage occurred in the promoters and exons of genes. Integration of the DNA methylome and transcriptome identified regions in three genes that inversely correlated with gene expression: wingless-type mouse mammary tumor virus integration site family, member 2B (WNT2B) and two eicosanoid synthesis pathway enzymes (prostacyclin synthase and prostaglandin D2 synthase). These findings were independently validated by RT-PCR and bisulfite sequencing. Network analysis of the data also identified candidate molecular interactions relevant to fibrosis pathology. CONCLUSIONS Our definition of a genome-wide fibrosis-specific DNA methylome provides new gene networks and epigenetic states by which to understand mechanisms of pathological gene expression that lead to fibrosis. Our data also provide a basis for development of new fibrosis-specific therapies, as genes dysregulated in fibrotic Crohn's disease, following functional validation, can serve as new therapeutic targets.
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Affiliation(s)
- Tammy Sadler
- Department of Pathobiology, Cleveland Clinic Lerner Research Institute, 9500 Euclid Avenue/NC-22, Cleveland, OH 44195 USA
| | - Jeffrey M Bhasin
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH USA.,Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue/NC-22, Cleveland, OH 44195 USA
| | - Yaomin Xu
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN USA
| | - Jill Barnholz-Sloan
- Institute for Computational Biology, Case Western Reserve University, Cleveland, OH USA
| | - Yanwen Chen
- Institute for Computational Biology, Case Western Reserve University, Cleveland, OH USA
| | - Angela H Ting
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH USA.,Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue/NC-22, Cleveland, OH 44195 USA
| | - Eleni Stylianou
- Department of Pathobiology, Cleveland Clinic Lerner Research Institute, 9500 Euclid Avenue/NC-22, Cleveland, OH 44195 USA.,Department of Gastroenterology and Hepatology, Digestive Diseases Institute, Cleveland Clinic, Cleveland, OH USA
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13
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Huisman C, van der Wijst MGP, Schokker M, Blancafort P, Terpstra MM, Kok K, van der Zee AGJ, Schuuring E, Wisman GBA, Rots MG. Re-expression of Selected Epigenetically Silenced Candidate Tumor Suppressor Genes in Cervical Cancer by TET2-directed Demethylation. Mol Ther 2015; 24:536-47. [PMID: 26686387 DOI: 10.1038/mt.2015.226] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/11/2015] [Indexed: 12/18/2022] Open
Abstract
DNA hypermethylation is extensively explored as therapeutic target for gene expression modulation in cancer. Here, we re-activated hypermethylated candidate tumor suppressor genes (TSGs) (C13ORF18, CCNA1, TFPI2, and Maspin) by TET2-induced demethylation in cervical cancer cell lines. To redirect TET2 to hypermethylated TSGs, we engineered zinc finger proteins (ZFPs), which were first fused to the transcriptional activator VP64 to validate effective gene re-expression and confirm TSG function. ChIP-Seq not only revealed enriched binding of ZFPs to their intended sequence, but also considerable off-target binding, especially at promoter regions. Nevertheless, results obtained by targeted re-expression using ZFP-VP64 constructs were in line with cDNA overexpression; both revealed strong growth inhibition for C13ORF18 and TFPI2, but not for CCNA1 and Maspin. To explore effectivity of locus-targeted demethylation, ZFP-TET2 fusions were constructed which efficiently demethylated genes with subsequent gene re-activation. Moreover, targeting TET2 to TFPI2 and C13ORF18, but not CCNA1, significantly decreased cell growth, viability, and colony formation in cervical cancer cells compared to a catalytically inactive mutant of TET2. These data underline that effective re-activation of hypermethylated genes can be achieved through targeted DNA demethylation by TET2, which can assist in realizing sustained re-expression of genes of interest.
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Affiliation(s)
- Christian Huisman
- Department of Pathology and Medical Biology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands.,Current address: Department of Pediatrics, Oregon Health and Science University, Portland, Oregon, USA
| | - Monique G P van der Wijst
- Department of Pathology and Medical Biology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
| | - Matthijs Schokker
- Department of Pathology and Medical Biology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
| | - Pilar Blancafort
- Cancer Epigenetics Group, The Harry Perkins Institute for Medical Research, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Martijn M Terpstra
- Department of Genetics, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
| | - Klaas Kok
- Department of Genetics, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
| | - Ate G J van der Zee
- Department of Gynecological Oncology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
| | - Ed Schuuring
- Department of Pathology and Medical Biology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
| | - G Bea A Wisman
- Department of Gynecological Oncology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
| | - Marianne G Rots
- Department of Pathology and Medical Biology, University Medical Center Groningen (UMCG), University of Groningen, Groningen, The Netherlands
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14
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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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15
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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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16
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Stolzenburg S, Beltran AS, Swift-Scanlan T, Rivenbark AG, Rashwan R, Blancafort P. Stable oncogenic silencing in vivo by programmable and targeted de novo DNA methylation in breast cancer. Oncogene 2015; 34:5427-35. [PMID: 25684141 PMCID: PMC4633433 DOI: 10.1038/onc.2014.470] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 11/15/2014] [Accepted: 12/09/2014] [Indexed: 12/16/2022]
Abstract
With the recent comprehensive mapping of cancer genomes, there is now a need for functional approaches to edit the aberrant epigenetic state of key cancer drivers to reprogram the epi-pathology of the disease. In this study we utilized a programmable DNA-binding methyltransferase to induce targeted incorporation of DNA methylation (DNAme) in the SOX2 oncogene in breast cancer through a six zinc finger (ZF) protein linked to DNA methyltransferase 3A (ZF-DNMT3A). We demonstrated long-lasting oncogenic repression, which was maintained even after suppression of ZF-DNMT3A expression in tumor cells. The de novo DNAme was faithfully propagated and maintained through cell generations even after the suppression of the expression of the chimeric methyltransferase in the tumor cells. Xenograft studies in NUDE mice demonstrated stable SOX2 repression and long-term breast tumor growth inhibition, which lasted for >100 days post implantation of the tumor cells in mice. This was accompanied with a faithful maintenance of DNAme in the breast cancer implants. In contrast, downregulation of SOX2 by ZF domains engineered with the Krueppel-associated box repressor domain resulted in a transient and reversible suppression of oncogenic gene expression. Our results indicated that targeted de novo DNAme of the SOX2 oncogenic promoter was sufficient to induce long-lasting epigenetic silencing, which was not only maintained during cell division but also significantly delayed the tumorigenic phenotype of cancer cells in vivo, even in the absence of treatment. Here, we outline a genome-based targeting approach to long-lasting tumor growth inhibition with potential applicability to many other oncogenic drivers that are currently refractory to drug design.
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Affiliation(s)
- S Stolzenburg
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Western Australia & School of Anatomy, Physiology and Human Biology, M309, The University of Western Australia, Nedlands, Western Australia, Australia.,Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - A S Beltran
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - T Swift-Scanlan
- Lineberger Comprehensive Cancer Center/School of Nursing, University of North Carolina, Chapel Hill, NC, USA
| | - A G Rivenbark
- Department of Pathology and Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - R Rashwan
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Western Australia & School of Anatomy, Physiology and Human Biology, M309, The University of Western Australia, Nedlands, Western Australia, Australia
| | - P Blancafort
- Cancer Epigenetics Group, The Harry Perkins Institute of Medical Research, Western Australia & School of Anatomy, Physiology and Human Biology, M309, The University of Western Australia, Nedlands, Western Australia, Australia.,Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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17
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Lane MD, Seelig B. Advances in the directed evolution of proteins. Curr Opin Chem Biol 2014; 22:129-36. [PMID: 25309990 DOI: 10.1016/j.cbpa.2014.09.013] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 09/13/2014] [Indexed: 12/21/2022]
Abstract
Natural evolution has produced a great diversity of proteins that can be harnessed for numerous applications in biotechnology and pharmaceutical science. Commonly, specific applications require proteins to be tailored by protein engineering. Directed evolution is a type of protein engineering that yields proteins with the desired properties under well-defined conditions and in a practical time frame. While directed evolution has been employed for decades, recent creative developments enable the generation of proteins with previously inaccessible properties. Novel selection strategies, faster techniques, the inclusion of unnatural amino acids or modifications, and the symbiosis of rational design approaches and directed evolution continue to advance protein engineering.
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Affiliation(s)
- Michael D Lane
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA; BioTechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - Burckhard Seelig
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA; BioTechnology Institute, University of Minnesota, St. Paul, MN, USA.
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18
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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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19
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Targeting DNA methylation to the genome. Biotechniques 2014; 57:106-10. [PMID: 25209045 DOI: 10.2144/000114203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Proving direct relationships between DNA alterations and phenotypes is challenging. For epigenetics researchers, linking DNA methylation with human disease is no exception. But Patrick Lo looks at how two researchers are developing new methods to try to trace the road from DNA methylation to human biology.
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20
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Lee RS, Sawa A. Environmental stressors and epigenetic control of the hypothalamic-pituitary-adrenal axis. Neuroendocrinology 2014; 100:278-87. [PMID: 25427939 PMCID: PMC4428760 DOI: 10.1159/000369585] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 11/05/2014] [Indexed: 02/05/2023]
Abstract
In this review, we provide a brief summary of several key studies that broaden our understanding of stress and its epigenetic control of the function and behavior of the hypothalamic-pituitary-adrenal (HPA) axis. Clinical and animal studies suggest a link among exposure to stress, dysregulation of the HPA axis, and susceptibility to neuropsychiatric illnesses. Recent studies have supported the notion that exposure to glucocorticoids and stress in various forms, durations, and intensities during different periods of development leads to long-lasting maladaptive HPA axis response in the brain. They demonstrate that this maladaptive response is comprised of persistent epigenetic changes in the function of HPA axis-associated genes that govern homeostatic levels of glucocorticoids. Stressors and/or disruption of glucocorticoid dynamics also target genes such as brain-derived neurotrophic factor(BDNF) and tyrosine hydroxylase(TH) that are important for neuronal function and behavior. While a definitive role for epigenetic mechanisms remains unclear, these emerging studies implicate glucocorticoid signaling and its ability to alter the epigenetic landscape as one of the key mechanisms that alter the function of the HPA axis and its associated cascades. We also suggest some of the requisite studies and techniques that are important, such as additional candidate gene approaches, genome-wide epigenomic screens, and innovative functional and behavioral studies, in order to further explore and define the relationship between epigenetics and HPA axis biology. Additional studies examining stress-induced epigenetic changes of HPA axis genes, aided by innovative techniques and methodologies, are needed to advance our understanding of this relationship and lead to better preventive, diagnostic, and corrective measures.
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Affiliation(s)
- Richard S Lee
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Md., USA
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