The authors thank Jan Appel for his excellent technical assistance during the establishment of this protocol. Work in the Rada-Iglesias laboratory is supported by CMMC intramural funding, DFG Research Grants (RA 2547/1-1, RA 2547/2-1, and TE 1007/3-1), the UoC Advanced Researcher Group Grant, and the CECAD Grant.

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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=H3K4me3+breadth+is+linked+to+cell+identity+and+transcriptional+consistency.">H3K4me3 breadth is linked to cell identity and transcriptional consistency.</a> Cell. 158 (3), 673-688 (2014).</li><li>Rehimi, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenomics-Based+Identification+of+Major+Cell+Identity+Regulators+within+Heterogeneous+Cell+Populations.">Epigenomics-Based Identification of Major Cell Identity Regulators within Heterogeneous Cell Populations.</a> Cell Rep. 17 (11), 3062-3076 (2016).</li><li>Whyte, W. 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The authors do not have any competing financial interests to be disclosed.

Epigenomic profiling of histone modification using ChIP-seq can be used to improve the functional annotation of vertebrate genomes in different cellular contexts4,5,18. These epigenomic profiles can be used, among other things, to identify enhancer elements, to define the regulatory state of enhancers (i.e., active, primed, or poised), and to define major cell identity regulators in different biological or pathological ...

Histone post-translational modifications are directly involved in various chromatin-dependent processes, including transcription, replication and DNA repair1,2,3. Moreover, different histone modifications show positive (e.g., H3K4me3 and H3K27ac) or negative (e.g., H3K9me3 and H3K27me3) correlations with gene expression and can be broadly defined as activating or repressive histone marks, respectively2,3. Consequently, global histone modification maps, also referred to as epigenomic maps, have emerged as powerful and universal tools to functionally annotate vertebrate genomes4,5. For example, distal regulatory sequences such as enhancers can be identified based on the presence of specific chromatin signatures (e.g., active enhancers: H3K4me1 and H3K27ac), which distinguish them from proximal promoter regions (e.g., active promoters: H3K4me3)6,7,8. On the other hand, genes with major cell identity regulatory functions are typically found with broad chromatin domains marked with H3K4me3 or H3K27me3, depending on the transcriptionally active or inactive status of the underlying genes, respectively9,10. Similarly, the expression of major cell identity genes seems to be frequently controlled by multiple and spatially clustered enhancers (i.e., super-enhancers), which can be identified as broad H3K27ac-marked domains11.
Currently, histone modification maps are generated using ChIP-seq technology, which in comparison to previous approaches such as ChIP-chip (ChIP coupled to microarrays) provides higher resolution, fewer artifacts, less noise, greater coverage, and lower costs12. Nevertheless, the generation of epigenomic maps using ChIP-seq technology has its inherent limitations, mostly associated with the capacity to successfully perform ChIP in the samples of interest. Traditional ChIP protocols typically required millions of cells, which limit the applicability of this method to in vitro cell lines or cells that can easily be isolated in vivo (e.g., blood cells). In the last few years, a number of modified ChIP protocols compatible with low cell numbers have been described13,14,15,16. However, these protocols are specifically designed to be coupled with next-generation sequencing (i.e., ChIP-seq), and they typically use ad hoc library preparation methods13,14,15,16.
Here, we described a ChIP protocol that can be used to investigate histone modification profiles using low to intermediate cell numbers (5 x 104 - 5 x 105 cells) at either selected loci (i.e., ChIP-qPCR) or globally (i.e., ChIP-seq) (Figure 1). When coupled to ChIP-seq technology, our ChIP protocol can be used together with standard library preparation methods, thus making it broadly accessible to many laboratories10. This protocol has been used to investigate several histone marks (e.g., H3K4me3, H3K27me3, and H3K27ac) in different chicken embryonic tissues (e.g., spinal neural tube (SNT), frontonasal prominences, and epiblast). However, we anticipate that it should be broadly applicable to other organisms in which biologically and/or clinically relevant samples can be only obtained in low amounts.

<table>
	<tbody>
		<tr>
			<td>Reagent</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BSA powder</td>
			<td>Carl Roth</td>
			<td>3737.3</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Saline buffer (PBS)</td>
			<td>Sigma Aldrich</td>
			<td>D8537</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris-HCL pH8.0</td>
			<td>Sigma Aldrich</td>
			<td>T1503</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Carl Roth</td>
			<td>3957.2</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Carl Roth</td>
			<td>8043.2</td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Carl Roth</td>
			<td>3054.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Na-Deoxycholate</td>
			<td>Sigma Aldrich</td>
			<td>D6750-24</td>
			<td></td>
		</tr>
		<tr>
			<td>N-lauroylsarcosine</td>
			<td>Sigma Aldrich</td>
			<td>61743-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Hepes</td>
			<td>Applichem</td>
			<td>A3724,0250</td>
			<td></td>
		</tr>
		<tr>
			<td>LiCl</td>
			<td>Carl Roth</td>
			<td>3739.2</td>
			<td></td>
		</tr>
		<tr>
			<td>NP-40</td>
			<td>Sigma Aldrich</td>
			<td>I3021-100ml</td>
			<td></td>
		</tr>
		<tr>
			<td>SDS</td>
			<td>Carl Roth</td>
			<td>1833</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein G/magnetic beads</td>
			<td>Invitrogen</td>
			<td>1004D</td>
			<td></td>
		</tr>
		<tr>
			<td>37% Formaldehyde</td>
			<td>Sigma Aldrich</td>
			<td>252549-1L</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>RNase</td>
			<td>Peqlab</td>
			<td>12-RA-03</td>
			<td></td>
		</tr>
		<tr>
			<td>Proteinase K</td>
			<td>Sigma Aldrich</td>
			<td>46.35 E</td>
			<td></td>
		</tr>
		<tr>
			<td>Na-butyrate</td>
			<td>Sigma Aldrich</td>
			<td>SLB2659V</td>
			<td></td>
		</tr>
		<tr>
			<td>Proteinase inhibitor</td>
			<td>Roche</td>
			<td>5892791001</td>
			<td></td>
		</tr>
		<tr>
			<td>SYBRgreen Mix</td>
			<td>biozym</td>
			<td>617004</td>
			<td></td>
		</tr>
		<tr>
			<td>dH2O</td>
			<td>Sigma Aldrich</td>
			<td>W4502</td>
			<td></td>
		</tr>
		<tr>
			<td>1Kb ladder</td>
			<td>Thermofisher</td>
			<td>SM1333</td>
			<td></td>
		</tr>
		<tr>
			<td>Orange G</td>
			<td>Sigma Alrich</td>
			<td>03756-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>Invitrogen</td>
			<td>16500-500</td>
			<td></td>
		</tr>
		<tr>
			<td>0.25% Trypsin-EDTA (1X)</td>
			<td>Gibco</td>
			<td>25200-072</td>
			<td></td>
		</tr>
		<tr>
			<td>Octylphenol Ethoxylate (Triton X 100)</td>
			<td>Roth</td>
			<td>3051.4</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM (Dulbecco&#180;s Modified Eagle Medium)</td>
			<td>Gibco</td>
			<td>31331-028</td>
			<td></td>
		</tr>
		<tr>
			<td>Gel loading tips Multiflex</td>
			<td>A.Hartenstein</td>
			<td>GS21</td>
			<td></td>
		</tr>
		<tr>
			<td>qPCR Plates</td>
			<td>Sarstedt</td>
			<td>721,985,202</td>
			<td></td>
		</tr>
		<tr>
			<td>384 well</td>
			<td>Sarstedt</td>
			<td>721,985,202</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL tubes</td>
			<td>Sarstedt</td>
			<td>72,706</td>
			<td></td>
		</tr>
		<tr>
			<td>100-1000&#181;l Filter tips</td>
			<td>Sarstedt</td>
			<td>70,762,211</td>
			<td></td>
		</tr>
		<tr>
			<td>2-20&#181;l Filter tips</td>
			<td>Sarstedt</td>
			<td>70,760,213</td>
			<td></td>
		</tr>
		<tr>
			<td>2-200&#181;l Filter tips</td>
			<td>Sarstedt</td>
			<td>70,760,211</td>
			<td></td>
		</tr>
		<tr>
			<td>0.5-10&#181;l Filter tips</td>
			<td>Sarstedt</td>
			<td>701,116,210</td>
			<td></td>
		</tr>
		<tr>
			<td>H3K27me3 antibody</td>
			<td>Active Motif</td>
			<td>39155</td>
			<td></td>
		</tr>
		<tr>
			<td>H3K27ac antibody</td>
			<td>Active Motif</td>
			<td>39133</td>
			<td></td>
		</tr>
		<tr>
			<td>H3K4me3 antibody</td>
			<td>Active Motif</td>
			<td>39159</td>
			<td></td>
		</tr>
		<tr>
			<td>H3K4me2 antibody</td>
			<td>Active Motif</td>
			<td>39141</td>
			<td></td>
		</tr>
		<tr>
			<td>End Repair Mix</td>
			<td>Illumina</td>
			<td>FC-121-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>Paramagnetic beads</td>
			<td>Beckman Coulter</td>
			<td>A63881</td>
			<td></td>
		</tr>
		<tr>
			<td>Resuspension buffer</td>
			<td>Illumina</td>
			<td>FC-121-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>A-Tailing Mix</td>
			<td>Illumina</td>
			<td>FC-121-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>Ligation Mix</td>
			<td>Illumina</td>
			<td>FC-121-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>RNA Adapter Indexes</td>
			<td>Illumina</td>
			<td>RS-122-2101</td>
			<td></td>
		</tr>
		<tr>
			<td>Stop Ligation Buffer</td>
			<td>Illumina</td>
			<td>FC-121-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>PCR Primer Cocktail</td>
			<td>Illumina</td>
			<td>FC-121-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>Enhanced PCR Mix</td>
			<td>Illumina</td>
			<td>FC-121-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>Genomic DNA ladder</td>
			<td>Agilent</td>
			<td>5067-5582</td>
			<td></td>
		</tr>
		<tr>
			<td>Elution Buffer</td>
			<td>Agilent</td>
			<td>19086</td>
			<td></td>
		</tr>
		<tr>
			<td>Sample Buffer</td>
			<td>Agilent</td>
			<td>5067-5582</td>
			<td></td>
		</tr>
		<tr>
			<td>Library Quantification Kit</td>
			<td>Kapa Biosystems</td>
			<td>KK4835 &#8211; 07960204001</td>
			<td></td>
		</tr>
		<tr>
			<td>Fertile chicken white eggs</td>
			<td>LSL Rhein Main</td>
			<td>KN: 15968</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle (Neoject)</td>
			<td>A.Hartenstein</td>
			<td>10001</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe (Ecoject 10ml)</td>
			<td>Dispomed witt oHG</td>
			<td>21010</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Hermle</td>
			<td>Z 216 MK</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermoshaker</td>
			<td>ITABIS</td>
			<td>MKR13</td>
			<td></td>
		</tr>
		<tr>
			<td>Sonicator</td>
			<td>Active Motive</td>
			<td>EpiShear probe sonicator</td>
			<td></td>
		</tr>
		<tr>
			<td>Sonicator</td>
			<td>Diagenode</td>
			<td>Bioruptor Plus</td>
			<td></td>
		</tr>
		<tr>
			<td>Rotator</td>
			<td>Stuart</td>
			<td>SB3</td>
			<td></td>
		</tr>
		<tr>
			<td>Variable volume (5&#8211;1,000 &#956;l) pipettes</td>
			<td>Eppendorf</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Timer</td>
			<td>Sigma</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic holder</td>
			<td>Thermo Fisher</td>
			<td>DynaMag-2 12321D</td>
			<td></td>
		</tr>
		<tr>
			<td>Table spinner</td>
			<td>Heathrow Scientific</td>
			<td>Sprout</td>
			<td></td>
		</tr>
		<tr>
			<td>Mixer</td>
			<td>LMS</td>
			<td>VTX 3000L</td>
			<td></td>
		</tr>
		<tr>
			<td>Real-Time PCR Cycler</td>
			<td>Roche</td>
			<td>Light Cycler; Serial Nr.5662</td>
			<td></td>
		</tr>
		<tr>
			<td>PCR Cycler</td>
			<td>Applied Biosystems</td>
			<td>Gene Amp PCR System 9700</td>
			<td></td>
		</tr>
		<tr>
			<td>DNA and RNA quality control system</td>
			<td>Agilent</td>
			<td>Agilent 4200 TapeStation System</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Dumont</td>
			<td>5-Inox-H</td>
			<td></td>
		</tr>
		<tr>
			<td>Perforated spoon</td>
			<td>World precision instruments</td>
			<td>501997</td>
			<td></td>
		</tr>
	</tbody>
</table>

chromatin immunoprecipitation (chip) protocol for low-abundance embryonic samples

Chromatin immunoprecipitation (ChIP) is a widely-used technique for mapping the localization of post-translationally modified histones, histone variants, transcription factors, or chromatin-modifying enzymes at a given locus or on a genome-wide scale. The combination of ChIP assays with next-generation sequencing (i.e., ChIP-Seq) is a powerful approach to globally uncover gene regulatory networks and to improve the functional annotation of genomes, especially of non-coding regulatory sequences. ChIP protocols normally require large amounts of cellular material, thus precluding the applicability of this method to investigating rare cell types or small tissue biopsies. In order to make the ChIP assay compatible with the amount of biological material that can typically be obtained in vivo during early vertebrate embryogenesis, we describe here a simplified ChIP protocol in which the number of steps required to complete the assay were reduced to minimize sample loss. This ChIP protocol has been successfully used to investigate different histone modifications in various embryonic chicken and adult mouse tissues using low to medium cell numbers (5 x 104 - 5 x 105 cells). Importantly, this protocol is compatible with ChIP-seq technology using standard library preparation methods, thus providing global epigenomic maps in highly relevant embryonic tissues.

To illustrate the performance of our ChIP protocol, we performed ChIP-seq experiments using pooled SNT sections from HH19 chicken embryos, maxillary prominences of HH22 chicken embryos, and stage-HH3 chicken embryos to investigate the binding profiles of various histone modifications (i.e., H3K4me2, H3K27ac, H3K4me3, and H3K27me3). Once ChIP DNAs were obtained, the sonication efficiency was evaluated by agarose gel electrophoresis of the corresponding input DNAs (<strong class="x...

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Chromatin Immunoprecipitation ChIP Protocol for Low-abundance Embryonic Samples

Here, we describe a chromatin immunoprecipitation (ChIP) and ChIP-seq library preparation protocol to generate global epigenomic profiles from low-abundance chicken embryonic samples.

Chromatin Immunoprecipitation (ChIP) Protocol for Low-abundance Embryonic Samples

Chromatin immunoprecipitation (ChIP) is a widely-used technique for mapping the localization of post-translationally modified histones, histone variants, ...

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Genetics

15.6K Views.  University of Cologne. Here, we describe a chromatin immunoprecipitation (ChIP) and ChIP-seq library preparation protocol to generate global epigenomic profiles from low-abundance chicken embryonic samples.

Video: Chromatin Immunoprecipitation ChIP Protocol for Low-abundance Embryonic Samples

Sequential Salt Extractions for the Analysis of Bulk Chromatin Binding Properties of Chromatin Modifying Complexes

Elucidation of the binding properties of chromatin-targeting proteins can be very challenging due to the complex nature of chromatin and the heterogeneous nature of most mammalian chromatin-modifying complexes. In order to overcome these hurdles, we have adapted a sequential salt extraction (SSE) assay for evaluating the relative binding affinities of chromatin-bound complexes. This easy and straightforward assay can be used by non-experts to evaluate the relative difference in binding affinity of two related complexes, the changes in affinity of a complex when a subunit is lost or an individual domain is inactivated, and the change in binding affinity after alterations to the chromatin landscape. By sequentially re-suspending bulk chromatin in increasing amounts of salt, we are able to profile the elution of a particular protein from chromatin. Using these profiles, we are able to determine how alterations in a chromatin-modifying complex or alterations to the chromatin environment affect binding interactions. Coupling SSE with other in vitro and in vivo assays, we can determine the roles of individual domains and proteins on the functionality of a complex in a variety of chromatin environments.

Sequential salt extraction of chromatin bound proteins is a useful tool for determining the binding properties of large protein complexes. This method can be employed to evaluate the role of individual subunits or domains in the overall affinity of a protein complex to bulk chromatin.

Elucidation of the binding properties of chromatin-targeting proteins can be very challenging due to the complex nature of chromatin and the heterogeneous ...

Analysis of the c-KIT Ligand Promoter Using Chromatin Immunoprecipitation

Multiple cellular processes, including DNA replication and repair, DNA recombination, and gene expression, require interactions between proteins and DNA. Therefore, DNA-protein interactions regulate multiple physiological, pathophysiological, and biological functions, such as cell differentiation, cell proliferation, cell cycle control, chromosome stability, epigenetic gene regulation, and cell transformation. In eukaryotic cells, the DNA interacts with histone and nonhistone proteins and is condensed into chromatin. Several technical tools can be used to analyze DNA-protein interactions, such as the Electrophoresis (gel) Mobility Shift Assay (EMSA) and DNase I footprinting. However, these techniques analyze the protein-DNA interaction in vitro, not within the cellular context. Chromatin immunoprecipitation (ChIP) is a technique that captures proteins at their specific DNA binding sites, thereby allowing for the identification of DNA-protein interactions within their chromatin context. It is done by fixation&#160;of the DNA-protein interaction, followed by&#160;immunoprecipitation of the protein of interest. Subsequently, the genomic site that the protein was bound to is characterized. Here, we describe and discuss ChIP and demonstrate its analytical value for the identification of the Transforming Growth Factor-&#946; (TGF-&#946;)-induced binding of the transcription factor SMAD2 to SMAD Binding Elements (SBE) within the promoter region of the tyrosine-protein kinase Kit (c-KIT) receptor ligand Stem Cell Factor (SCF).

DNA-protein interactions are essential for multiple biological processes. During the evaluation of cellular functions, the analysis of DNA-protein interactions is indispensable for understanding gene regulation. Chromatin immunoprecipitation (ChIP) is a powerful tool to analyze such interactions in vivo.

Multiple cellular processes, including DNA replication and repair, DNA recombination, and gene expression, require interactions between proteins and DNA. ...

Chromatin Immunoprecipitation (ChIP) in Mouse T-cell Lines

Signaling pathways regulate gene expression programs via the modulation of the chromatin structure at different levels, such as by post-translational modifications (PTMs) of histone tails, the exchange of canonical histones with histone variants, and nucleosome eviction. Such regulation requires the binding of signal-sensitive transcription factors (TFs) that recruit chromatin-modifying enzymes at regulatory elements defined as enhancers. Understanding how signaling cascades regulate enhancer activity requires a comprehensive analysis of the binding of TFs, chromatin modifying enzymes, and the occupancy of specific histone marks and histone variants. Chromatin immunoprecipitation (ChIP) assays utilize highly specific antibodies to immunoprecipitate specific protein/DNA complexes. The subsequent analysis of the purified DNA allows for the identification the region occupied by the protein recognized by the antibody. This work describes a protocol to efficiently perform ChIP of histone proteins in a mature mouse T-cell line. The presented protocol allows for the performance of ChIP assays in a reasonable timeframe and with high reproducibility.

Chromatin Immunoprecipitation ChIP in Mouse T-cell Lines

This work describes a protocol for chromatin immunoprecipitation (ChIP) using a mature mouse T-cell line. This protocol is suitable to investigate the distribution of specific histone marks at specific promoter sites or genome-wide.

Signaling pathways regulate gene expression programs via the modulation of the chromatin structure at different levels, such as by post-translational ...

Generation of Native Chromatin Immunoprecipitation Sequencing Libraries for Nucleosome Density Analysis

We present a modified native chromatin immunoprecipitation sequencing (ChIP-seq) experimental protocol compatible with a Gaussian mixture distribution based analysis methodology (nucleosome density ChIP-seq; ndChIP-seq) that enables the generation of combined measurements of micrococcal nuclease (MNase) accessibility with histone modification genome-wide. Nucleosome position and local density, and the posttranslational modification of their histone subunits, act in concert to regulate local transcription states. Combinatorial measurements of nucleosome accessibility with histone modification generated by ndChIP-seq allows for the simultaneous interrogation of these features. The ndChIP-seq methodology is applicable to small numbers of primary cells inaccessible to cross-linking based ChIP-seq protocols. Taken together, ndChIP-seq enables the measurement of histone modification in combination with local nucleosome density to obtain new insights into shared mechanisms that regulate RNA transcription within rare primary cell populations.

We present a modified native chromatin immunoprecipitation sequencing (ChIP-seq) methodology for the generation of sequence datasets suitable for a nucleosome density ChIP-seq analytical framework integrating micrococcal nuclease (MNase) accessibility with histone modification measurements.

We present a modified native chromatin immunoprecipitation sequencing (ChIP-seq) experimental protocol compatible with a Gaussian mixture distribution ...

Chromatin Immunoprecipitation (ChIP) of Histone Modifications from Saccharomyces cerevisiae

Histone post-translational modifications (PTMs), such as acetylation, methylation and phosphorylation, are dynamically regulated by a series of enzymes that add or remove these marks in response to signals received by the cell. These PTMS are key contributors to the regulation of processes such as gene expression control and DNA repair. Chromatin immunoprecipitation (chIP) has been an instrumental approach for dissecting the abundance and localization of many histone PTMs throughout the genome in response to diverse perturbations to the cell. Here, a versatile method for performing chIP of post-translationally modified histones from the budding yeast Saccharomyces cerevisiae (S. cerevisiae) is described. This method relies on crosslinking of proteins and DNA using formaldehyde treatment of yeast cultures, generation of yeast lysates by bead beating, solubilization of chromatin fragments by micrococcal nuclease, and immunoprecipitation of histone-DNA complexes. DNA associated with the histone mark of interest is purified and subjected to quantitative PCR analysis to evaluate its enrichment at multiple loci throughout the genome. Representative experiments probing the localization of the histone marks H3K4me2 and H4K16ac in wildtype and mutant yeast are discussed to demonstrate data analysis and interpretation. This method is suitable for a variety of histone PTMs and can be performed with different mutant strains or in the presence of diverse environmental stresses, making it an excellent tool for investigating changes in chromatin dynamics under different conditions.

Chromatin Immunoprecipitation ChIP of Histone Modifications from Saccharomyces cerevisiae

Here, we describe a protocol for chromatin immunoprecipitation of modified histones from the budding yeast Saccharomyces cerevisiae. Immunoprecipitated DNA is subsequently used for quantitative PCR to interrogate the abundance and localization of histone post-translational modifications throughout the genome.

Histone post-translational modifications (PTMs), such as acetylation, methylation and phosphorylation, are dynamically regulated by a series of enzymes ...

CRISPR-Mediated Reorganization of Chromatin Loop Structure

Recent studies have clearly shown that long-range, three-dimensional chromatin looping interactions play a significant role in the regulation of gene expression, but whether looping is responsible for or a result of alterations in gene expression is still unknown. Until recently, how chromatin looping affects the regulation of gene activity and cellular function has been relatively ambiguous, and limitations in existing methods to manipulate these structures prevented in-depth exploration of these interactions. To resolve this uncertainty, we engineered a method for selective and reversible chromatin loop re-organization using CRISPR-dCas9 (CLOuD9). The dynamism of the CLOuD9 system has been demonstrated by successful localization of CLOuD9 constructs to target genomic loci to modulate local chromatin conformation. Importantly, the ability to reverse the induced contact and restore the endogenous chromatin conformation has also been confirmed. Modulation of gene expression with this method establishes the capacity to regulate cellular gene expression and underscores the great potential for applications of this technology in creating stable de novo chromatin loops that markedly affect gene expression in the contexts of cancer and development.

Chromatin looping plays a significant role in gene regulation; however, there have been no technological advances that allow for selective and reversible modification of chromatin loops. Here we describe a powerful system for chromatin loop re-organization using CRISPR-dCas9 (CLOuD9), demonstrated to selectively and reversibly modulate gene expression at targeted loci.

Recent studies have clearly shown that long-range, three-dimensional chromatin looping interactions play a significant role in the regulation of gene ...

Chromatin Immunoprecipitation of Murine Brown Adipose Tissue

Most cellular processes are regulated by transcriptional modulation of specific gene programs. Such modulation is achieved through the combined actions of a wide range of transcription factors (TFs) and cofactors mediating transcriptional activation or repression via changes in chromatin structure. Chromatin immunoprecipitation (ChIP) is a useful molecular biology approach for mapping histone modifications and profiling transcription factors/cofactors binding to DNA, thus providing a snapshot of the dynamic nuclear changes occurring during different biological processes.
To study transcriptional regulation in adipose tissue, samples derived from in vitro cell cultures of immortalized or primary cell lines are often favored in ChIP assays because of the abundance of starting material and reduced biological variability. However, these models represent a limited snapshot of the actual chromatin state in living organisms. Thus, there is a critical need for optimized protocols to perform ChIP on adipose tissue samples derived from animal models.
Here we describe a protocol for efficient ChIP-seq of both histone modifications and non-histone proteins in brown adipose tissue (BAT) isolated from a mouse. The protocol is optimized for investigating genome-wide localization of proteins of interest and epigenetic markers in the BAT, which is a morphologically and physiologically distinct tissue amongst fat depots.

Here we describe a protocol for efficient chromatin immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq) of brown adipose tissue (BAT) isolated from a mouse. This protocol is suitable for both mapping histone modifications and investigating genome-wide localization of non-histone proteins of interest in vivo.

Most cellular processes are regulated by transcriptional modulation of specific gene programs. Such modulation is achieved through the combined actions of ...

Chromatin Immunoprecipitation Assay Using Micrococcal Nucleases in Mammalian Cells

To express cellular phenotypes in organisms, living cells execute gene expression accordingly, and transcriptional programs play a central role in gene expression. The cellular transcriptional machinery and its chromatin modification proteins coordinate to regulate transcription. To analyze transcriptional regulation at the molecular level, several experimental methods such as electrophoretic mobility shift, transient reporter and chromatin immunoprecipitation (ChIP) assays are available. We describe a modified ChIP assay in detail in this article because of its advantages in directly showing histone modifications and the interactions between proteins and DNA in cells. One of the key steps in a successful ChIP assay is chromatin shearing. Although sonication is commonly used for shearing chromatin, it is difficult to identify reproducible conditions. Instead of shearing chromatin by sonication, we utilized enzymatic digestion with micrococcal nuclease (MNase) to obtain more reproducible results. In this article, we provide a straightforward ChIP assay protocol using MNase.

Chromatin immunoprecipitation (ChIP) is a powerful tool for understanding the molecular mechanisms of gene regulation. However, the method involves difficulties in obtaining reproducible chromatin fragmentation by mechanical shearing. Here, we provide an improved protocol for a ChIP assay using enzymatic digestion.

To express cellular phenotypes in organisms, living cells execute gene expression accordingly, and transcriptional programs play a central role in gene ...

A Method to Study de novo Formation of Chromatin Domains

The organization and structure of chromatin domains are unique to individual cell lineages. Their misregulation might lead to a loss in cellular identity and/or disease. Despite tremendous efforts, our understanding of the formation and propagation of chromatin domains is still limited. Chromatin domains have been studied under steady-state conditions, which are not conducive to following the initial events during their establishment. Here, we present a method to inducibly reconstruct chromatin domains and follow their re-formation as a function of time. Although, first applied to the case of PRC2-mediated repressive chromatin domain formation, it could be easily adapted to other chromatin domains. The modification of and/or the combination of this method with genomics and imaging technologies will provide invaluable tools to study the establishment of chromatin domains in great detail. We believe that this method will revolutionize our understanding of how chromatin domains form and interact with each other.

A Method to Study de novo Formation of Chromatin Domains

This method is designed to follow formation of PRC2-mediated chromatin domains in cell lines, and the method can be adapted to many other systems.

The organization and structure of chromatin domains are unique to individual cell lineages. Their misregulation might lead to a loss in cellular identity ...

Discovering CsgD Regulatory Targets in Salmonella Biofilm Using Chromatin Immunoprecipitation and High-Throughput Sequencing (ChIP-seq)

Chromatin immunoprecipitation followed by sequencing (ChIP-seq) is a technique that can be used to discover the regulatory targets of transcription factors, histone modifications, and other DNA-associated proteins. ChIP-seq data can also be used to find differential binding of transcription factors in different environmental conditions or cell types. Initially, ChIP was performed through hybridization on a microarray (ChIP-chip); however, ChIP-seq has become the preferred method through technological advancements, decreasing financial barriers to sequencing, and massive amounts of high-quality data output. Techniques of performing ChIP-seq with bacterial biofilms, a major source of persistent and chronic infections, are described in this protocol. ChIP-seq is performed on Salmonella enterica serovar Typhimurium biofilm and planktonic cells, targeting the master biofilm regulator, CsgD, to determine differential binding in the two cell types. Here, we demonstrate the appropriate amount of biofilm to harvest, normalizing to a planktonic control sample, homogenizing biofilm for cross-linker access, and performing routine ChIP-seq steps to obtain high quality sequencing results.

Discovering CsgD Regulatory Targets in Salmonella Biofilm Using Chromatin Immunoprecipitation and High-Throughput Sequencing ChIP-seq

Chromatin immunoprecipitation coupled with next-generation sequencing (ChIP-seq) is a method used to establish interactions between transcription factors and the genomic sequences they control. This protocol outlines techniques for performing ChIP-seq with bacterial biofilms, using Salmonella enterica serovar Typhimurium bacterial biofilm as an example.

Chromatin immunoprecipitation followed by sequencing (ChIP-seq) is a technique that can be used to discover the regulatory targets of transcription ...