We thank Dr. Bas van Steensel for providing the DamID mammalian expression vectors. We thank Yale Center for Genome Analysis and the Genomics Core in Yale Stem Cell Center for advice on preparing NGS libraries and implementing high throughput DNA sequencing. This work was supported by the startup funding from Yale School of Medicine, a Scientist Development Grant from American Heart Association (12SDG11630031) and a Seed Grant from Connecticut Innovations, Inc. (13-SCA-YALE-15).

<ol>
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The authors have nothing to disclose.

Whether Dam-tagged proteins retain the functions of endogenous proteins should be examined before a DamID-seq experiment. The subcellular localization of Dam-tagged nuclear envelope proteins should always be determined and compared with that of the endogenous proteins. For studying transcription factors, it is suggested to examine whether the Dam-fusion protein can rescue the functions of the endogenous protein in regulating gene expression. This functional test can be performed in organisms in which knockout mutants of ...

DNA adenine methyltransferase identification (DamID) 1,2 is a method to detect protein-DNA interactions in vivo and is an alternative approach to chromatin immunoprecipitation (ChIP) 3. It uses a relatively low amount of cells and does not require chemical cross-linking of protein with DNA or a highly specific antibody. The latter is particularly helpful when the target protein is loosely or indirectly associated with DNA. DamID has been successfully used to map the binding sites of a variety of proteins including nuclear envelope proteins 4-10, chromatin associated proteins 11-13, chromatin modifying enzymes 14, transcription factors and co-factors15-18 and RNAi machineries 19. The method is applicable in multiple organisms including S. cerevisiae 13, S. pombe 7, C. elegans 9,17, D. melanogaster 5,11,18,20, A. thaliana 21,22 as well as mouse and human cell lines 6,8,10,23,24.
The development of the DamID assay was based on the specific detection of adenine-methylated DNA fragments in eukaryotic cells that lack endogenous adenine methylation 2. An expressed fusion protein, consisting of the DNA-binding protein of interest and E. coli DNA adenine methyltransferase (Dam), can methylate the adenine base in GATC sequences that are in spatial proximity (most significantly within 1 kb and up to roughly 5 kb) to the binding sites of the protein in the genome 2. The modified DNA fragments can be specifically amplified and hybridized to microarrays to detect the genomic binding sites of the protein of interest 1,25,26. This original DamID method was limited by the availability of microarrays and the density of predetermined probes. We have therefore integrated high throughput sequencing into DamID 10 and designated the method as DamID-seq. The large number of short reads generated from DamID-seq enables precise localization of protein-DNA interactions genome-wide. We found that DamID-seq provided a higher resolution and a wider dynamic range than DamID by microarray for studying genome-nuclear lamina (NL) associations 10. This improved method allows probing NL associations within gene structures 10 and facilitates comparisons with other high throughput sequencing data, such as ChIP-seq and RNA-seq.
The DamID-seq protocol described here was initially developed for mapping genome-NL associations 10. We generated a fusion protein by tethering mouse or human Lamin B1 to E. coli DNA adenine methyltransferase and tested the protocol in 3T3 mouse embryonic fibroblasts, C2C12 mouse myoblasts 10 and IMR90 human fetal lung fibroblasts (data not published). In this protocol, we start with constructing vectors and expressing Dam-tethered fusion proteins by lentiviral infection in mammalian cells 24. Next, we describe the detailed protocols of amplifying adenine-methylated DNA fragments and preparing sequencing libraries that should be applicable in other organisms.

<table><tbody><tr><td>ViraPower Lentiviral Expression Systems</td><td>Life Technologies</td><td>K4950-00, K4960-00, K4970-00, K4975-00, K4980-00, K4985-00, K4990-00, K367-20, K370-20, and K371-20</td><td></td></tr><tr><td>Gateway BP Clonase II Enzyme Mix</td><td>Life Technologies</td><td>11789-020</td><td></td></tr><tr><td>Gateway LR Clonase II Enzyme Mix</td><td>Life Technologies</td><td>11791-020</td><td></td></tr><tr><td>DNeasy Blood &amp;amp; Tissue Kit (250)</td><td>QIAGEN</td><td>69506 or 69504&amp;nbsp;&amp;nbsp;</td><td></td></tr><tr><td>Gateway pDONR 201</td><td>Life Technologies</td><td>11798-014</td><td></td></tr><tr><td>293T cells</td><td>American Type Culture Collection</td><td>CRL-11268</td><td></td></tr><tr><td>&lt;a href=&quot;http://www.lifetechnologies.com/order/catalog/product/25300054&quot;&gt;Trypsin-EDTA (0.05%), phenol red&lt;/a&gt;</td><td>Life Technologies</td><td>25300-054</td><td></td></tr><tr><td>DMEM, high glucose, pyruvate</td><td>Life Technologies</td><td>11995-065</td><td></td></tr><tr><td>Fetal Bovine Serum</td><td>Sigma</td><td>F4135</td><td></td></tr><tr><td>Tris</td><td></td><td></td><td>brand not critical</td></tr><tr><td>EDTA</td><td></td><td></td><td>brand not critical</td></tr><tr><td>200 Proof EtOH</td><td></td><td></td><td>brand not critical</td></tr><tr><td>Isopropanol</td><td></td><td></td><td>brand not critical</td></tr><tr><td>Sodium Acetate</td><td></td><td></td><td>brand not critical</td></tr><tr><td>DpnI</td><td>New England Biolabs</td><td>R0176</td><td>supplied with buffer</td></tr><tr><td>DamID adaptors &quot;AdRt&quot; and &quot;AdRb&quot;</td><td>Integrated DNA Technologies</td><td></td><td>sequences available in ref. 24; no phosphorylation of the 5&#039; or 3&#039; end to prevent self-ligation.</td></tr><tr><td>T4 DNA Ligase</td><td>Roche Life Science</td><td>10481220001</td><td>supplied with buffer</td></tr><tr><td>DpnII</td><td>New England Biolabs</td><td>R0543</td><td>supplied with buffer</td></tr><tr><td>DamID PCR primer &quot;AdR_PCR&quot;</td><td>Integrated DNA Technologies</td><td></td><td>sequences available in ref. 24</td></tr><tr><td>Deoxynucleotide (dNTP) Solution Set</td><td>New England Biolabs</td><td>N0446</td><td>100 mM each of dATP, dCTP, dGTP and dTTP</td></tr><tr><td>Advantage 2&amp;nbsp; Polymerase Mix</td><td>Clontech</td><td>639201</td><td>supplied with buffer</td></tr><tr><td>1Kb Plus DNA Ladder</td><td>Life Technologies</td><td>10787018</td><td>1.0 &amp;micro;g/&amp;micro;l</td></tr><tr><td>QIAquick PCR Purification Kit</td><td>QIAGEN</td><td>28104 or 28106</td><td></td></tr><tr><td>MinElute PCR Purification Kit</td><td>QIAGEN</td><td>28004 or 28006</td><td>for an elution volume of less than 30 &amp;micro;l</td></tr><tr><td>SPRI beads / Agencourt AMPure XP</td><td>Beckman Coulter</td><td>A63880</td><td>apply extra mixing and more elution time if less than 40 &amp;micro;l elution buffer is used</td></tr><tr><td>Buffer EB</td><td>QIAGEN</td><td>19086</td><td></td></tr><tr><td>NEBNext dsDNA Fragmentase</td><td>New England Biolabs</td><td>M0348</td><td>supplied with buffer</td></tr><tr><td>T4 DNA Ligase Reaction Buffer</td><td>New England Biolabs</td><td>B0202</td><td></td></tr><tr><td>T4 DNA Polymerase</td><td>New England Biolabs</td><td>M0203</td><td></td></tr><tr><td>DNA Polymerase I, Large (Klenow) Fragment</td><td>New England Biolabs</td><td>M0210</td><td></td></tr><tr><td>T4 Polynuleotide Kinase</td><td>New England Biolabs</td><td>M0201</td><td></td></tr><tr><td>Klenow Fragment (3&amp;rsquo; &amp;#8594; 5&amp;rsquo; exo-)</td><td>New England Biolabs</td><td>M0212</td><td>supplied with buffer</td></tr><tr><td>sequencing adaptors</td><td>Integrated DNA Technologies</td><td></td><td>sequences available in ref. 28</td></tr><tr><td>Quick Ligation Kit</td><td>New England Biolabs</td><td>M2200</td><td>used in 3.4.3; supplied with Quick Ligation Reaction Buffer and Quick T4 DNA Ligase</td></tr><tr><td>sequencing primer 1 and 2</td><td>Integrated DNA Technologies</td><td></td><td>sequences available in ref. 28</td></tr><tr><td>KAPA HiFi PCR Kit</td><td>Kapa Biosystems</td><td>KK2101 or KK2102</td><td>supplied with KAPA HiFi DNA Polymerase, 5x KAPA HiFi Fidelity Buffer and 10 mM dNTP mix</td></tr><tr><td>agarose</td><td>Sigma Aldrich</td><td>A4679</td><td></td></tr><tr><td>ethidium bromide</td><td>Sigma Aldrich</td><td>E1510-10ML</td><td>10 mg/ml</td></tr><tr><td>QIAquick Gel Extraction Kit</td><td>QIAGEN</td><td>28704 or 28706</td><td></td></tr><tr><td>iTaq Universal SYBR Green Supermix</td><td>Bio-Rad Laboratories</td><td>1725121 or 1725122</td><td></td></tr><tr><td>Spectrophotometer</td><td></td><td></td><td>brand not critical</td></tr><tr><td>0.45 &amp;#956;m PVDF Filter</td><td></td><td></td><td>brand not critical</td></tr><tr><td>25 ml Seringe</td><td></td><td></td><td>brand not critical</td></tr><tr><td>10 cm Tissue Culture Plates</td><td></td><td></td><td>brand not critical</td></tr><tr><td>6-well Tissue Culture Plates</td><td></td><td></td><td>brand not critical</td></tr><tr><td>S1000 Thermal Cycler</td><td>Bio-Rad Laboratories</td><td></td><td></td></tr><tr><td>C1000 Touch Thermal Cycler</td><td>Bio-Rad Laboratories</td><td></td><td>for qPCR</td></tr><tr><td>Vortex Mixer</td><td></td><td></td><td>brand not critical</td></tr><tr><td>Dry Block Heater or Thermomixer</td><td></td><td></td><td>brand not critical</td></tr><tr><td>Microcentrifuge</td><td></td><td></td><td>brand not critical</td></tr><tr><td>Gel electrophoresis system with power supply</td><td></td><td></td><td>brand not critical</td></tr><tr><td>Magnet stand</td><td></td><td></td><td>for purification of DNA with SPRI beads; should hold 1.5-2 ml tubes; brand not critical</td></tr><tr><td>UV transilluminator</td><td></td><td></td><td>brand not critical</td></tr><tr><td>E-gel electrophoresis system</td><td>Life Technologies</td><td>G6400, G6500, G6512ST</td><td></td></tr></tbody></table>

damid-seq: genome-wide mapping of protein-dna interactions by high throughput sequencing of adenine-methylated dna fragments

The DNA adenine methyltransferase identification (DamID) assay is a powerful method to detect protein-DNA interactions both locally and genome-wide. It is an alternative approach to chromatin immunoprecipitation (ChIP). An expressed fusion protein consisting of the protein of interest and the E. coli DNA adenine methyltransferase can methylate the adenine base in GATC motifs near the sites of protein-DNA interactions. Adenine-methylated DNA fragments can then be specifically amplified and detected. The original DamID assay detects the genomic locations of methylated DNA fragments by hybridization to DNA microarrays, which is limited by the availability of microarrays and the density of predetermined probes. In this paper, we report the detailed protocol of integrating high throughput DNA sequencing into DamID (DamID-seq). The large number of short reads generated from DamID-seq enables detecting and localizing protein-DNA interactions genome-wide with high precision and sensitivity. We have used the DamID-seq assay to study genome-nuclear lamina (NL) interactions in mammalian cells, and have noticed that DamID-seq provides a high resolution and a wide dynamic range in detecting genome-NL interactions. The DamID-seq approach enables probing NL associations within gene structures and allows comparing genome-NL interaction maps with other functional genomic data, such as ChIP-seq and RNA-seq.

The Dam-V5-LmnB1 fusion protein was verified to be co-localized with the endogenous Lamin B protein by immunofluorescence staining (Figure 1).
The successful PCR amplification of adenine-methylated DNA fragments is a key step for DamID-seq. The experimental samples should amplify a smear of 0.2 - 2 kb while the negative controls (without DpnI, without ligase or without PCR template) should result in no-or clearl...

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DamID-seq: Genome-wide Mapping of Protein-DNA Interactions by High Throughput Sequencing of Adenine-methylated DNA Fragments

We describe herein an assay by coupling DNA adenine methyltransferase identification (DamID) to high throughput sequencing (DamID-seq). This improved method provides a higher resolution and a wider dynamic range, and allows analyzing DamID-seq data in conjunction with other high throughput sequencing data such as ChIP-seq, RNA-seq, etc.

The DNA adenine methyltransferase identification (DamID) assay is a powerful method to detect protein-DNA interactions both locally and genome-wide. It is ...

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Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

19.3K Views.  Yale University School of Medicine. We describe herein an assay by coupling DNA adenine methyltransferase identification (DamID) to high throughput sequencing (DamID-seq). This improved method provides a higher resolution and a wider dynamic range, and allows analyzing DamID-seq data in conjunction with other high throughput sequencing data such as ChIP-seq, RNA-seq, etc.

Video: DamID-seq: Genome-wide Mapping of Protein-DNA Interactions by High Throughput Sequencing of Adenine-methylated DNA Fragments

Methyl-binding DNA capture Sequencing for Patient Tissues

Methylation is one of the essential epigenetic modifications to the DNA, which is responsible for the precise regulation of genes required for stable development and differentiation of different tissue types. Dysregulation of this process is often the hallmark of various diseases like cancer. Here, we outline one of the recent sequencing techniques, Methyl-Binding DNA Capture sequencing (MBDCap-seq), used to quantify methylation in various normal and disease tissues for large patient cohorts. We describe a detailed protocol of this affinity enrichment approach along with a bioinformatics pipeline to achieve optimal quantification. This technique has been used to sequence hundreds of patients across various cancer types as a part of the 1,000 methylome project (Cancer Methylome System).

Here we present a protocol to investigate genome wide DNA methylation in large scale clinical patient screening studies using the Methyl-Binding DNA Capture sequencing (MBDCap-seq or MBD-seq) technology and the subsequent bioinformatics analysis pipeline.

Methylation is one of the essential epigenetic modifications to the DNA, which is responsible for the precise regulation of genes required for stable ...

Genetics

Genome-wide Mapping of Protein-DNA Interactions with ChEC-seq in Saccharomyces cerevisiae

Genome-wide mapping of protein-DNA interactions is critical for understanding gene regulation, chromatin remodeling, and other chromatin-resident processes. Formaldehyde crosslinking followed by chromatin immunoprecipitation and high-throughput sequencing (X-ChIP-seq) has been used to gain many valuable insights into genome biology. However, X-ChIP-seq has notable limitations linked to crosslinking and sonication. Native ChIP avoids these drawbacks by omitting crosslinking, but often results in poor recovery of chromatin-bound proteins. In addition, all ChIP-based methods are subject to antibody quality considerations. Enzymatic methods for mapping protein-DNA interactions, which involve fusion of a protein of interest to a DNA-modifying enzyme, have also been used to map protein-DNA interactions. We recently combined one such method, chromatin endogenous cleavage (ChEC), with high-throughput sequencing as ChEC-seq. ChEC-seq relies on fusion of a chromatin-associated protein of interest to micrococcal nuclease (MNase) to generate targeted DNA cleavage in the presence of calcium in living cells. ChEC-seq is not based on immunoprecipitation and so circumvents potential concerns with crosslinking, sonication, chromatin solubilization, and antibody quality while providing high resolution mapping with minimal background signal. We envision that ChEC-seq will be a powerful counterpart to ChIP, providing an independent means by which to both validate ChIP-seq findings and discover new insights into genomic regulation.

Genome-wide Mapping of Protein-DNA Interactions with ChEC-seq in Saccharomyces cerevisiae

We describe chromatin endogenous cleavage coupled with high-throughput sequencing (ChEC-seq), a chromatin immunoprecipitation (ChIP)-orthogonal method for mapping protein binding sites genome-wide with micrococcal nuclease (MNase) fusion proteins.

Genome-wide mapping of protein-DNA interactions is critical for understanding gene regulation, chromatin remodeling, and other chromatin-resident ...

Adaptation of Hybridization Capture of Chromatin-associated Proteins for Proteomics to Mammalian Cells

The hybridization capture of chromatin-associated proteins for proteomics (HyCCAPP) technology was initially developed to uncover novel DNA-protein interactions in yeast. It allows analysis of a target region of interest without the need for prior knowledge about likely proteins bound to the target region. This, in theory, allows HyCCAPP to be used to analyze any genomic region of interest, and it provides sufficient flexibility to work in different cell systems. This method is not meant to study binding sites of known transcription factors, a task better suited for Chromatin Immunoprecipitation (ChIP) and ChIP-like methods. The strength of HyCCAPP lies in its ability to explore DNA regions for which there is limited or no knowledge about the proteins bound to it. It can also be a convenient method to avoid biases (present in ChIP-like methods) introduced by protein-based chromatin enrichment using antibodies. Potentially, HyCCAPP can be a powerful tool to uncover truly novel DNA-protein interactions. To date, the technology has been predominantly applied to yeast cells or to high copy repeat sequences in mammalian cells. In order to become the powerful tool we envision, HyCCAPP approaches need to be optimized to efficiently capture single-copy loci in mammalian cells. Here, we present our adaptation of the initial yeast HyCCAPP capture protocol to human cell lines, and show that single-copy chromatin regions can be efficiently isolated with this modified protocol.

This is a method to identify novel DNA-interacting proteins at specific target loci, relying on sequence-specific capture of crosslinked chromatin for subsequent proteomic analyses. No prior knowledge about potential binding proteins, nor cell modifications are required. Initially developed for yeast, the technology has now been adapted for mammalian cells.

The hybridization capture of chromatin-associated proteins for proteomics (HyCCAPP) technology was initially developed to uncover novel DNA-protein ...

High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease (ChIP-Exo)

Identification of specific protein-DNA interactions on the genome is important for understanding gene regulation. Chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) is widely used to identify genome-wide binding locations of DNA-binding proteins. However, the ChIP-seq method is limited by its heterogeneity in length of sonicated DNA fragments and non-specific background DNA, resulting in low mapping resolution and uncertainty in DNA-binding sites. To overcome these limitations, the combination of ChIP with exonuclease digestion (ChIP-exo) utilizes 5&#8217; to 3&#8217; exonuclease digestion to trim the heterogeneously sized immunoprecipitated DNA to the protein-DNA crosslinking site. Exonuclease treatment also eliminates non-specific background DNA. The library-prepared and exonuclease-digested DNA can be sent for high-throughput sequencing. The ChIP-exo method allows for near base-pair mapping resolution with greater detection sensitivity and reduced background signal. An optimized ChIP-exo protocol for mammalian cells and next-generation sequencing is described below.

High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease ChIP-Exo

Precise determination of protein-binding locations across the genome is important for understanding gene regulation. Here we describe a&#160;genomic mapping method that treats chromatin-immunoprecipitated DNA with exonuclease digestion (ChIP-exo) followed by high-throughput sequencing. This method detects protein-DNA interactions with near base-pair mapping resolution and high signal-to-noise ratio in mammalian neurons.

Identification of specific protein-DNA interactions on the genome is important for understanding gene regulation. Chromatin immunoprecipitation coupled ...

Mapping Mammalian 3D Genome Interactions with Micro-C-XL

Three-dimensional (3D) chromosome organization is a major factor in genome regulation and cell-type specification. For example, cis-regulatory elements, known as enhancers, are thought to regulate the activity of distal promoters via interaction in 3D space. Genome-wide chromosome conformation capture (3C)-technologies, such as Hi-C, have transformed our understanding of how genomes are organized in cells. The current understanding of 3D genome organization is limited by the resolution with which the topological organization of chromosomes in 3D space can be resolved. Micro-C-XL measures chromosome folding with resolution at the level of the nucleosome, the basic unit of chromatin, by utilizing micrococcal nuclease (MNase) to fragment genomes during the chromosome conformation capture protocol. This results in an improved signal-to-noise ratio in the measurements, thus facilitating the better detection of insulation sites and chromosome loops compared to other genome-wide 3D technologies. A visually supported, detailed, step-by-step protocol for preparing high-quality Micro-C-XL samples from mammalian cells is presented in this article.

A protocol for mapping the three-dimensional genome organization with nucleosome resolution using the genome-wide chromosome conformation capture method Micro-C-XL is presented here.

Three-dimensional (3D) chromosome organization is a major factor in genome regulation and cell-type specification. For example, cis-regulatory elements, ...

Beginner-Friendly Single-Language Pipeline for CUT&RUN Data Analysis

Introductory Analysis and Validation of CUT&#38;RUN Sequencing Data

The CUT&amp;RUN technique facilitates detection of protein-DNA interactions across the genome. Typical applications of CUT&amp;RUN include profiling changes in histone tail modifications or mapping transcription factor chromatin occupancy. Widespread adoption of CUT&amp;RUN is driven, in part, by technical advantages over conventional ChIP-seq that include lower cell input requirements, lower sequencing depth requirements, and increased sensitivity with reduced background signal due to a lack of cross-linking agents that otherwise mask antibody epitopes. Widespread adoption of CUT&amp;RUN has also been achieved through the generous sharing of reagents by the Henikoff lab and the development of commercial kits to accelerate adoption for beginners. As technical adoption of CUT&amp;RUN increases, CUT&amp;RUN sequencing analysis and validation become critical bottlenecks that must be surmounted to enable complete adoption by predominantly wet lab teams. CUT&amp;RUN analysis typically begins with quality control checks on raw sequencing reads to assess sequencing depth, read quality, and potential biases. Reads are then aligned to a reference genome sequence assembly, and several bioinformatics tools are subsequently employed to annotate genomic regions of protein enrichment, confirm data interpretability, and draw biological conclusions. Although multiple in silico analysis pipelines have been developed to support CUT&amp;RUN data analysis, their complex multi-module structure and usage of multiple programming languages render the platforms difficult for bioinformatics beginners who may lack familiarity with multiple programming languages but wish to understand the CUT&amp;RUN analysis procedure and customize their analysis pipelines. Here, we provide a single-language step-by-step CUT&amp;RUN analysis pipeline protocol designed for users with any level of bioinformatics experience. This protocol includes completing critical quality checks to validate that the sequencing data is suitable for biological interpretation. We expect that following the introductory protocol provided in this article combined with downstream peak annotation will allow users to draw biological insights from their own CUT&amp;RUN datasets.

Author Spotlight: Investigating the Role of Repetitive DNA Misregulation in Cancer Initiation and Immunotherapy Resistance

This protocol guides bioinformatics beginners through an introductory CUT&amp;RUN analysis pipeline that enables users to complete an initial analysis and validation of CUT&amp;RUN sequencing data. Completing the analysis steps described here, combined with downstream peak annotation, will allow users to draw mechanistic insights into chromatin regulation.

The CUT&amp;RUN technique facilitates detection of protein-DNA interactions across the genome. Typical applications of CUT&amp;RUN include profiling ...

CD Spectroscopy to Study DNA-Protein Interactions

Circular dichroism (CD) spectroscopy is a simple and convenient method to investigate the secondary structure and interactions of biomolecules. Recent advancements in CD spectroscopy have enabled the study of DNA-protein interactions and conformational dynamics of DNA in different microenvironments in detail for a better understanding of transcriptional regulation in vivo. The area around a potential transcription zone needs to be unwound for transcription to occur. This is a complex process requiring the coordination of histone modifications, binding of the transcription factor to DNA, and other chromatin remodeling activities. Using CD spectroscopy, it is possible to study conformational changes in the promoter region caused by regulatory proteins, such as ATP-dependent chromatin remodelers, to promote transcription. The conformational changes occurring in the protein can also be monitored. In addition, queries regarding the affinity of the protein towards its target DNA and sequence specificity can be addressed by incorporating mutations in the target DNA. In short, the unique understanding of this sensitive and inexpensive method can predict changes in chromatin dynamics, thereby improving the understanding of transcriptional regulation.

The interaction of an ATP-dependent chromatin remodeler with a DNA ligand is described using CD spectroscopy. The induced conformational changes on a gene promoter analyzed by the peaks generated can be used to understand the mechanism of transcriptional regulation.

Circular dichroism (CD) spectroscopy is a simple and convenient method to investigate the secondary structure and interactions of biomolecules. Recent ...

Biochemistry

Chromatin Interaction Analysis with Paired-End Tag Sequencing (ChIA-PET) for Mapping Chromatin Interactions and Understanding Transcription Regulation

Genomes are organized into three-dimensional structures, adopting higher-order conformations inside the micron-sized nuclear spaces 7, 2, 12. Such architectures are not random and involve interactions between gene promoters and regulatory elements 13. The binding of transcription factors to specific regulatory sequences brings about a network of transcription regulation and coordination 1, 14. 
Chromatin Interaction Analysis by Paired-End Tag Sequencing (ChIA-PET) was developed to identify these higher-order chromatin structures 5,6. Cells are fixed and interacting loci are captured by covalent DNA-protein cross-links. To minimize non-specific noise and reduce complexity, as well as to increase the specificity of the chromatin interaction analysis, chromatin immunoprecipitation (ChIP) is used against specific protein factors to enrich chromatin fragments of interest before proximity ligation. Ligation involving half-linkers subsequently forms covalent links between pairs of DNA fragments tethered together within individual chromatin complexes. The flanking MmeI restriction enzyme sites in the half-linkers allow extraction of paired end tag-linker-tag constructs (PETs) upon MmeI digestion. As the half-linkers are biotinylated, these PET constructs are purified using streptavidin-magnetic beads. The purified PETs are ligated with next-generation sequencing adaptors and a catalog of interacting fragments is generated via next-generation sequencers such as the Illumina Genome Analyzer. Mapping and bioinformatics analysis is then performed to identify ChIP-enriched binding sites and ChIP-enriched chromatin interactions 8. 
We have produced a video to demonstrate critical aspects of the ChIA-PET protocol, especially the preparation of ChIP as the quality of ChIP plays a major role in the outcome of a ChIA-PET library. As the protocols are very long, only the critical steps are shown in the video.

Chromatin Interaction Analysis with Paired-End Tag Sequencing ChIA-PET for Mapping Chromatin Interactions and Understanding Transcription Regulation

Chromatin Interaction Analysis by Paired-End Tag Sequencing (ChIA-PET) is a method for de novo detection of chromatin interactions, for better understanding of transcriptional control.

Genomes are organized into three-dimensional structures, adopting higher-order conformations inside the micron-sized nuclear spaces 7, 2, 12. Such ...

DNA-affinity-purified Chip (DAP-chip) Method to Determine Gene Targets for Bacterial Two component Regulatory Systems

In vivo methods such as ChIP-chip are well-established techniques used to determine global gene targets for transcription factors. However, they are of limited use in exploring bacterial two component regulatory systems with uncharacterized activation conditions. Such systems regulate transcription only when activated in the presence of unique signals. Since these signals are often unknown, the in vitro microarray based method described in this video article can be used to determine gene targets and binding sites for response regulators. This DNA-affinity-purified-chip method may be used for any purified regulator in any organism with a sequenced genome. The protocol involves allowing the purified tagged protein to bind to sheared genomic DNA and then affinity purifying the protein-bound DNA, followed by fluorescent labeling of the DNA and hybridization to a custom tiling array. Preceding steps that may be used to optimize the assay for specific regulators are also described. The peaks generated by the array data analysis are used to predict binding site motifs, which are then experimentally validated. The motif predictions can be further used to determine gene targets of orthologous response regulators in closely related species. We demonstrate the applicability of this method by determining the gene targets and binding site motifs and thus predicting the function for a sigma54-dependent response regulator DVU3023 in the environmental bacterium Desulfovibrio vulgaris Hildenborough.

DNA-affinity-purified Chip DAP-chip Method to Determine Gene Targets for Bacterial Two component Regulatory Systems

This video article describes an in vitro microarray based method to determine the gene targets and binding sites for two component system response regulators.

In vivo methods such as ChIP-chip are well-established techniques used to determine global gene targets for transcription factors. However, they are of ...

Targeted DNA Methylation Analysis by Next-generation Sequencing

The role of epigenetic processes in the control of gene expression has been known for a number of years. DNA methylation at cytosine residues is of particular interest for epigenetic studies as it has been demonstrated to be both a long lasting and a dynamic regulator of gene expression. Efforts to examine epigenetic changes in health and disease have been hindered by the lack of high-throughput, quantitatively accurate methods. With the advent and popularization of next-generation sequencing (NGS) technologies, these tools are now being applied to epigenomics in addition to existing genomic and transcriptomic methodologies. For epigenetic investigations of cytosine methylation where regions of interest, such as specific gene promoters or CpG islands, have been identified and there is a need to examine significant numbers of samples with high quantitative accuracy, we have developed a method called Bisulfite Amplicon Sequencing (BSAS). This method combines bisulfite conversion with targeted amplification of regions of interest, transposome-mediated library construction and benchtop NGS. BSAS offers a rapid and efficient method for analysis of up to 10 kb of targeted regions in up to 96 samples at a time that can be performed by most research groups with basic molecular biology skills. The results provide absolute quantitation of cytosine methylation with base specificity. BSAS can be applied to any genomic region from any DNA source. This method is useful for hypothesis testing studies of target regions of interest as well as confirmation of regions identified in genome-wide methylation analyses such as whole genome bisulfite sequencing, reduced representation bisulfite sequencing, and methylated DNA immunoprecipitation sequencing.

Bisulfite amplicon sequencing (BSAS) is a method for quantifying cytosine methylation in targeted genomic regions of interest. This method uses bisulfite conversion paired with PCR amplification of target regions prior to next-generation sequencing to produce absolute quantitation of DNA methylation at a base-specific level.

The role of epigenetic processes in the control of gene expression has been known for a number of years. DNA methylation at cytosine residues is of ...

DamID-seq: Genome-wide Mapping of Protein-DNA Interactions by High Throughput Sequencing of Adenine-methylated DNA Fragments

Summary

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Chapters in this video

Methyl-binding DNA capture Sequencing for Patient Tissues

Genome-wide Mapping of Protein-DNA Interactions with ChEC-seq in Saccharomyces cerevisiae

Adaptation of Hybridization Capture of Chromatin-associated Proteins for Proteomics to Mammalian Cells

High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease (ChIP-Exo)

Mapping Mammalian 3D Genome Interactions with Micro-C-XL

Introductory Analysis and Validation of CUT&RUN Sequencing Data

CD Spectroscopy to Study DNA-Protein Interactions

Chromatin Interaction Analysis with Paired-End Tag Sequencing (ChIA-PET) for Mapping Chromatin Interactions and Understanding Transcription Regulation

DNA-affinity-purified Chip (DAP-chip) Method to Determine Gene Targets for Bacterial Two component Regulatory Systems

Targeted DNA Methylation Analysis by Next-generation Sequencing