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Akerman I, Maestro MA, De Franco E, Grau V, Flanagan S, García-Hurtado J, Mittler G, Ravassard P, Piemonti L, Ellard S, Hattersley AT, Ferrer J. Neonatal diabetes mutations disrupt a chromatin pioneering function that activates the human insulin gene. Cell Rep 2021; 35:108981. [PMID: 33852861 PMCID: PMC8052186 DOI: 10.1016/j.celrep.2021.108981] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 01/04/2021] [Accepted: 03/23/2021] [Indexed: 12/18/2022] Open
Abstract
Despite the central role of chromosomal context in gene transcription, human noncoding DNA variants are generally studied outside of their genomic location. This limits our understanding of disease-causing regulatory variants. INS promoter mutations cause recessive neonatal diabetes. We show that all INS promoter point mutations in 60 patients disrupt a CC dinucleotide, whereas none affect other elements important for episomal promoter function. To model CC mutations, we humanized an ∼3.1-kb region of the mouse Ins2 gene. This recapitulated developmental chromatin states and cell-specific transcription. A CC mutant allele, however, abrogated active chromatin formation during pancreas development. A search for transcription factors acting through this element revealed that another neonatal diabetes gene product, GLIS3, has a pioneer-like ability to derepress INS chromatin, which is hampered by the CC mutation. Our in vivo analysis, therefore, connects two human genetic defects in an essential mechanism for developmental activation of the INS gene.
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Affiliation(s)
- Ildem Akerman
- Institute of Metabolism and Systems Research (IMSR), Medical School, University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism (CEDAM), University of Birmingham, Birmingham, UK.
| | - Miguel Angel Maestro
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Elisa De Franco
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Vanessa Grau
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Sarah Flanagan
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Javier García-Hurtado
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Gerhard Mittler
- Max-Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
| | - Philippe Ravassard
- INSERM, CNRS, Paris Brain Institute - Hôpital Pitié-Salpêtrière, Paris, France
| | - Lorenzo Piemonti
- Diabetes Research Institute, IRCCS Ospedale San Raffaele and Università Vita-Salute San Raffaele, Milan, Italy
| | - Sian Ellard
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK; Exeter Genomics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Andrew T Hattersley
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Jorge Ferrer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain; Section of Genetics and Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
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Habib O, Mohd Sakri R, Ghazalli N, Chau DM, Ling KH, Abdullah S. Limited expression of non-integrating CpG-free plasmid is associated with increased nucleosome enrichment. PLoS One 2020; 15:e0244386. [PMID: 33347482 PMCID: PMC7751972 DOI: 10.1371/journal.pone.0244386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 12/08/2020] [Indexed: 11/18/2022] Open
Abstract
CpG-free pDNA was reported to facilitate sustained transgene expression with minimal inflammation in vivo as compared to CpG-containing pDNA. However, the expression potential and impact of CpG-free pDNA in in vitro model have never been described. Hence, in this study, we analyzed the transgene expression profiles of CpG-free pDNA in vitro to determine the influence of CpG depletion from the transgene. We found that in contrast to the published in vivo studies, CpG-free pDNA expressed a significantly lower level of luciferase than CpG-rich pDNA in several human cell lines. By comparing novel CpG-free pDNA carrying CpG-free GFP (pZGFP: 0 CpG) to CpG-rich GFP (pRGFP: 60 CpGs), we further showed that the discrepancy was not influenced by external factors such as gene transfer agent, cell species, cell type, and cytotoxicity. Moreover, pZGFP exhibited reduced expression despite having equal gene dosage as pRGFP. Analysis of mRNA distribution revealed that the mRNA export of pZGFP and pRGFP was similar; however, the steady state mRNA level of pZGFP was significantly lower. Upon further investigation, we found that the CpG-free transgene in non-integrating CpG-free pDNA backbone acquired increased nucleosome enrichment as compared with CpG-rich transgene, which may explain the observed reduced level of steady state mRNA. Our findings suggest that nucleosome enrichment could regulate non-integrating CpG-free pDNA expression and has implications on pDNA design.
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Affiliation(s)
- Omar Habib
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
| | - Rozita Mohd Sakri
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, Selangor, Malaysia
| | - Nadiah Ghazalli
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
| | - De-Ming Chau
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
| | - King-Hwa Ling
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
| | - Syahril Abdullah
- Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- UPM-MAKNA Cancer Research Laboratory, Institute of Bioscience, Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia
- * E-mail:
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Abstract
Background Chromatin accessibility is crucial for gene expression regulation in specific cells and in multiple biological processes. Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq) is an effective way to reveal chromatin accessibility at a genome-wide level. Through ATAC-seq, produced reads from a small number of cells reflect accessible regions that correspond to nucleosome positioning and transcription factor binding sites, due to probing hyperactive Tn5 transposase to DNA sequence. Conclusion In this review, we summarize both principle and features of ATAC-seq, highlight its applications in basic and clinical research. ATAC-seq has generated comprehensive chromatin accessible maps, and is becoming a powerful tool to understand dynamic gene expression regulation in stem cells, early embryos and tumors.
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Affiliation(s)
- Yuanyuan Sun
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, 668 Jimei Road, Xiamen, 361021 Fujian China
| | - Nan Miao
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, 668 Jimei Road, Xiamen, 361021 Fujian China
| | - Tao Sun
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, 668 Jimei Road, Xiamen, 361021 Fujian China
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Rodríguez-Gil A, Riedlinger T, Ritter O, Saul VV, Schmitz ML. Formaldehyde-assisted Isolation of Regulatory Elements to Measure Chromatin Accessibility in Mammalian Cells. J Vis Exp 2018. [PMID: 29658938 PMCID: PMC5933311 DOI: 10.3791/57272] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Appropriate gene expression in response to extracellular cues, that is, tissue- and lineage-specific gene transcription, critically depends on highly defined states of chromatin organization. The dynamic architecture of the nucleus is controlled by multiple mechanisms and shapes the transcriptional output programs. It is, therefore, important to determine locus-specific chromatin accessibility in a reliable fashion that is preferably independent from antibodies, which can be a potentially confounding source of experimental variability. Chromatin accessibility can be measured by various methods, including the Formaldehyde-Assisted Isolation of Regulatory Elements (FAIRE) assay, that allow the determination of general chromatin accessibility in a relatively low number of cells. Here we describe a FAIRE protocol that allows simple, reliable, and fast identification of genomic regions with a low protein occupancy. In this method, the DNA is covalently bound to the chromatin proteins using formaldehyde as a crosslinking agent and sheared to small pieces. The free DNA is afterwards enriched using phenol:chloroform extraction. The ratio of free DNA is determined by quantitative polymerase chain reaction (qPCR) or DNA sequencing (DNA-seq) compared to a control sample representing total DNA. The regions with a looser chromatin structure are enriched in the free DNA sample, thus allowing the identification of genomic regions with lower chromatin compaction.
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Affiliation(s)
- Alfonso Rodríguez-Gil
- Department of Oncohematology and Genetics. Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío;
| | - Tabea Riedlinger
- Institute of Biochemistry, Medical Faculty, Friedrichstrasse 24, Member of the German Center for Lung Research, Justus-Liebig-University
| | - Olesja Ritter
- Institute of Biochemistry, Medical Faculty, Friedrichstrasse 24, Member of the German Center for Lung Research, Justus-Liebig-University
| | - Vera V Saul
- Institute of Biochemistry, Medical Faculty, Friedrichstrasse 24, Member of the German Center for Lung Research, Justus-Liebig-University
| | - M Lienhard Schmitz
- Institute of Biochemistry, Medical Faculty, Friedrichstrasse 24, Member of the German Center for Lung Research, Justus-Liebig-University;
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Raurell-Vila H, Ramos-Rodríguez M, Pasquali L. Assay for Transposase Accessible Chromatin (ATAC-Seq) to Chart the Open Chromatin Landscape of Human Pancreatic Islets. Methods Mol Biol 2018; 1766:197-208. [PMID: 29605854 DOI: 10.1007/978-1-4939-7768-0_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The regulatory mechanisms that ensure an accurate control of gene transcription are central to cellular function, development and disease. Such mechanisms rely largely on noncoding regulatory sequences that allow the establishment and maintenance of cell identity and tissue-specific cellular functions.The study of chromatin structure and nucleosome positioning allowed revealing transcription factor accessible genomic sites with regulatory potential, facilitating the comprehension of tissue-specific cis-regulatory networks. Recently a new technique coupled with high-throughput sequencing named Assay for Transposase Accessible Chromatin (ATAC-seq) emerged as an efficient method to chart open chromatin genome wide. The application of such technique to different cell types allowed unmasking tissue-specific regulatory elements and characterizing cis-regulatory networks. Herein we describe the implementation of the ATAC-seq method to human pancreatic islets, a tissue playing a central role in the control of glucose metabolism.
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Reschen ME, Gaulton KJ, Lin D, Soilleux EJ, Morris AJ, Smyth SS, O'Callaghan CA. Lipid-induced epigenomic changes in human macrophages identify a coronary artery disease-associated variant that regulates PPAP2B Expression through Altered C/EBP-beta binding. PLoS Genet 2015; 11:e1005061. [PMID: 25835000 PMCID: PMC4383549 DOI: 10.1371/journal.pgen.1005061] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 02/09/2015] [Indexed: 01/17/2023] Open
Abstract
Genome-wide association studies (GWAS) have identified over 40 loci that affect risk of coronary artery disease (CAD) and the causal mechanisms at the majority of loci are unknown. Recent studies have suggested that many causal GWAS variants influence disease through altered transcriptional regulation in disease-relevant cell types. We explored changes in transcriptional regulation during a key pathophysiological event in CAD, the environmental lipid-induced transformation of macrophages to lipid-laden foam cells. We used a combination of open chromatin mapping with formaldehyde-assisted isolation of regulatory elements (FAIRE-seq) and enhancer and transcription factor mapping using chromatin immuno-precipitation (ChIP-seq) in primary human macrophages before and after exposure to atherogenic oxidized low-density lipoprotein (oxLDL), with resultant foam cell formation. OxLDL-induced foam cell formation was associated with changes in a subset of open chromatin and active enhancer sites that strongly correlated with expression changes of nearby genes. OxLDL-regulated enhancers were enriched for several transcription factors including C/EBP-beta, which has no previously documented role in foam cell formation. OxLDL exposure up-regulated C/EBP-beta expression and increased genomic binding events, most prominently around genes involved in inflammatory response pathways. Variants at CAD-associated loci were significantly and specifically enriched in the subset of chromatin sites altered by oxLDL exposure, including rs72664324 in an oxLDL-induced enhancer at the PPAP2B locus. OxLDL increased C/EBP beta binding to this site and C/EBP beta binding and enhancer activity were stronger with the protective A allele of rs72664324. In addition, expression of the PPAP2B protein product LPP3 was present in foam cells in human atherosclerotic plaques and oxLDL exposure up-regulated LPP3 in macrophages resulting in increased degradation of pro-inflammatory mediators. Our results demonstrate a genetic mechanism contributing to CAD risk at the PPAP2B locus and highlight the value of studying epigenetic changes in disease processes involving pathogenic environmental stimuli. Coronary artery disease is a complex disease where over 40 genomic loci contributing to genetic risk have been identified. However, identifying the precise variants, genomic elements and genes that mediate this risk at each locus has proved challenging. We hypothesized that some genetic risk variants may influence a key step in development of coronary artery disease, which occurs when macrophages encounter environmentally-derived lipid. These cells take up lipid and accumulate in atherosclerotic plaques in the walls of blood vessels where they contribute to the inflammatory atherosclerotic disease process. Therefore, we studied the effects of this lipid exposure on the genomic activity of these cells. Environmental lipid exposure triggered changes in transcriptional regulation and gene expression. Variants at coronary artery disease risk loci were enriched for genomic regions altered by lipid exposure. We studied one such risk variant rs72664324 in detail and found that it altered binding of the C/EBP-beta transcription factor and altered expression of the PPAP2B gene. PPAP2B encodes an enzyme that degrades pro-inflammatory substances. Our study demonstrates a hitherto unknown genetic mechanism underlying atherosclerotic heart disease and demonstrates the value of studying changes in transcriptional regulation in key disease processes involving environmental influences.
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Affiliation(s)
- Michael E. Reschen
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kyle J. Gaulton
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Da Lin
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Elizabeth J. Soilleux
- Nuffield Department of Clinical Laboratory Sciences, University of Oxford and Department of Cellular Pathology, John Radcliffe Hospital, Oxford, United Kingdom
| | - Andrew J. Morris
- Division of Cardiovascular Medicine, The Gill Heart Institute, University of Kentucky, Lexington, Kentucky, United States of America
- Department of Veterans Affairs Medical Center, Lexington, Kentucky, United States of America
| | - Susan S. Smyth
- Division of Cardiovascular Medicine, The Gill Heart Institute, University of Kentucky, Lexington, Kentucky, United States of America
- Department of Veterans Affairs Medical Center, Lexington, Kentucky, United States of America
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Yang CC, Buck MJ, Chen MH, Chen YF, Lan HC, Chen JJW, Cheng C, Liu CC. Discovering chromatin motifs using FAIRE sequencing and the human diploid genome. BMC Genomics 2013; 14:310. [PMID: 23656909 PMCID: PMC3655836 DOI: 10.1186/1471-2164-14-310] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 04/30/2013] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Specific chromatin structures are associated with active or inactive gene transcription. The gene regulatory elements are intrinsically dynamic and alternate between inactive and active states through the recruitment of DNA binding proteins, such as chromatin-remodeling proteins. RESULTS We developed a unique genome-wide method to discover DNA motifs associated with chromatin accessibility using formaldehyde-assisted isolation of regulatory elements with high-throughput sequencing (FAIRE-seq). We aligned the FAIRE-seq reads to the GM12878 diploid genome and subsequently identified differential chromatin-state regions (DCSRs) using heterozygous SNPs. The DCSR pairs represent the locations of imbalances of chromatin accessibility between alleles and are ideal to reveal chromatin motifs that may directly modulate chromatin accessibility. In this study, we used DNA 6-10mer sequences to interrogate all DCSRs, and subsequently discovered conserved chromatin motifs with significant changes in the occurrence frequency. To investigate their likely roles in biology, we studied the annotated protein associated with each of the top ten chromatin motifs genome-wide, in the intergenic regions and in genes, respectively. As a result, we found that most of these annotated motifs are associated with chromatin remodeling, reflecting their significance in biology. CONCLUSIONS Our method is the first one using fully phased diploid genome and FAIRE-seq to discover motifs associated with chromatin accessibility. Our results were collected to construct the first chromatin motif database (CMD), providing the potential DNA motifs recognized by chromatin-remodeling proteins and is freely available at http://syslab.nchu.edu.tw/chromatin.
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Affiliation(s)
- Chia-Chun Yang
- Institute of Molecular Biology, National Chung Hsing University, Taiwan, ROC
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Abstract
Advances in genome sequencing have progressed at a rapid pace, with increased throughput accompanied by plunging costs. But these advances go far beyond faster and cheaper. High-throughput sequencing technologies are now routinely being applied to a wide range of important topics in biology and medicine, often allowing researchers to address important biological questions that were not possible before. In this review, we discuss these innovative new approaches-including ever finer analyses of transcriptome dynamics, genome structure and genomic variation-and provide an overview of the new insights into complex biological systems catalyzed by these technologies. We also assess the impact of genotyping, genome sequencing and personal omics profiling on medical applications, including diagnosis and disease monitoring. Finally, we review recent developments in single-cell sequencing, and conclude with a discussion of possible future advances and obstacles for sequencing in biology and health.
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Affiliation(s)
- Wendy Weijia Soon
- Department of Genetics, Stanford University School of Medicine, Alway Building, 300 Pasteur Drive, Stanford, CA, USA
| | - Manoj Hariharan
- Department of Genetics, Stanford University School of Medicine, Alway Building, 300 Pasteur Drive, Stanford, CA, USA
| | - Michael P Snyder
- Department of Genetics, Stanford University School of Medicine, Alway Building, 300 Pasteur Drive, Stanford, CA, USA
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Abstract
Eukaryotic genomic DNA is combined with histones, nonhistone proteins, and RNA to form chromatin, which is extensively packaged hierarchically to fit inside a cell's nucleus. The nucleosome-comprising a histone octamer with 147 base pairs of DNA wrapped around it-is the initial level and the repeating unit of chromatin packaging, which electron microscopy first made visible to the human eye as "beads on a string" nearly four decades ago. The mechanism and nature of chromatin packaging are still under intense research. Recently, classic methods like chromatin immunoprecipitation and digestion with deoxyribonuclease and micrococcal nuclease have been combined with high-throughput sequencing to provide detailed nucleosome occupancy maps, and chromosome conformation capture and its variants have revealed that higher-order chromatin structure involves long-range loop formation between distant genomic elements. This review discusses the methods for identifying higher-order chromatin structure and the information they have provided on this important topic.
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Affiliation(s)
- Samin A Sajan
- Department of Medicine, Division of Human Genetics, University of Washington, Seattle, WA 98195, USA
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Simon JM, Giresi PG, Davis IJ, Lieb JD. Using formaldehyde-assisted isolation of regulatory elements (FAIRE) to isolate active regulatory DNA. Nat Protoc 2012; 7:256-67. [PMID: 22262007 DOI: 10.1038/nprot.2011.444] [Citation(s) in RCA: 250] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Eviction or destabilization of nucleosomes from chromatin is a hallmark of functional regulatory elements in eukaryotic genomes. Historically identified by nuclease hypersensitivity, these regulatory elements are typically bound by transcription factors or other regulatory proteins. FAIRE (formaldehyde-assisted isolation of regulatory elements) is an alternative approach to identify these genomic regions and has proven successful in a multitude of eukaryotic cell and tissue types. Cells or dissociated tissues are cross-linked briefly with formaldehyde, lysed and sonicated. Sheared chromatin is subjected to phenol/chloroform extraction and the isolated DNA, typically encompassing 1-3% of the human genome, is purified. We provide guidelines for quantitative analysis by PCR, microarrays or next-generation sequencing. Regulatory elements enriched by FAIRE have high concordance with those identified by nuclease hypersensitivity or chromatin immunoprecipitation (ChIP), and the entire procedure can be completed in 3 d. FAIRE has low technical variability, which allows its usage in large-scale studies of chromatin from normal or diseased tissues.
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