Name: chromatin immunoprecipitation (chip) protocol for low-abundance embryonic samples
Uploaded: 2017-08-29T14:00:00
Description: Watch this Scientific Journal Video about Chromatin Immunoprecipitation ChIP Protocol for Low-abundance Embryonic Samples at JoVE.com

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.

According to German animal care guidelines, no Institutional Animal Care and Use Committee (IACUC) approval was necessary to perform the chicken embryo experiments. According to the local guidelines, only experiments with chicken HH44 (18-day) embryos and older require IACUC approval. However, the embryos used in this study were all in earlier stages of embryonic development (i.e., HH19 (72 h)).
NOTE: The purpose of this protocol is to provide a detailed description of the ChIP assay ...

<ol>
	<li>Jenuwein, T., Allis, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Translating+the+histone+code.">Translating the histone code.</a> Science. 293 (5532), 1074-1080 (2001).</li><li>Kouzarides, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatin+modifications+and+their+function.">Chromatin modifications and their function.</a> Cell. 128 (4), 693-705 (2007).</li><li>Wang, Z., Schones, D. E., Zhao, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+human+epigenomes.">Characterization of human epigenomes.</a> Curr Opin. Genet Dev. 19 (2), 127-134 (2009).</li><li>ENCODE Project Consortium. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+integrated+encyclopedia+of+DNA+elements+in+the+human+genome.">An integrated encyclopedia of DNA elements in the human genome.</a> Nature. 489 (7414), 57-74 (2012).</li><li>Roadmap Epigenomics Consortium. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrative+analysis+of+111+reference+human+epigenomes.">Integrative analysis of 111 reference human epigenomes.</a> Nature. 518 (7539), 317-330 (2015).</li><li>Heintzman, N. D., 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=Histone+modifications+at+human+enhancers+reflect+global+cell-type-specific+gene+expression.">Histone modifications at human enhancers reflect global cell-type-specific gene expression.</a> Nature. 459 (7243), 108-112 (2009).</li><li>Rada-Iglesias, A., Bajpai, R., Swigut, T., Brugmann, S. A., Flynn, R. A., Wysocka, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+unique+chromatin+signature+uncovers+early+developmental+enhancers+in+humans.">A unique chromatin signature uncovers early developmental enhancers in humans.</a> Nature. 470 (7333), 279-283 (2011).</li><li>Creyghton, M. P., 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=Histone+H3K27ac+separates+active+from+poised+enhancers+and+predicts+developmental+state.">Histone H3K27ac separates active from poised enhancers and predicts developmental state.</a> Proc Nat Acad Sci USA. 107 (50), 21931-21936 (2010).</li><li>Benayoun, B. 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. 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=Master+transcription+factors+and+mediator+establish+super-enhancers+at+key+cell+identity+genes.">Master transcription factors and mediator establish super-enhancers at key cell identity genes.</a> Cell. 153 (2), 307-319 (2013).</li><li>Valouev, 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=Genome-wide+analysis+of+transcription+factor+binding+sites+based+on+ChIP-Seq+data.">Genome-wide analysis of transcription factor binding sites based on ChIP-Seq data.</a> Nat Methods. 5 (9), 829-834 (2008).</li><li>Dahl, J. 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=Broad+histone+H3K4me3+domains+in+mouse+oocytes+modulate+maternal-to-zygotic+transition.">Broad histone H3K4me3 domains in mouse oocytes modulate maternal-to-zygotic transition.</a> Nature. 537 (7621), 548-552 (2016).</li><li>Rotem, 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=Single-cell+ChIP-seq+reveals+cell+subpopulations+defined+by+chromatin+state.">Single-cell ChIP-seq reveals cell subpopulations defined by chromatin state.</a> Nat Biotech. 33 (11), 1165-1172 (2015).</li><li>Schmidl, C., Rendeiro, A. F., Sheffield, N. C., Bock, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ChIPmentation:+fast,+robust,+low-input+ChIP-seq+for+histones+and+transcription+factors.">ChIPmentation: fast, robust, low-input ChIP-seq for histones and transcription factors.</a> Nat Methods. 12 (10), 963-965 (2015).</li><li>Zhang, B., 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=Allelic+reprogramming+of+the+histone+modification+H3K4me3+in+early+mammalian+development.">Allelic reprogramming of the histone modification H3K4me3 in early mammalian development.</a> Nature. 537 (7621), 553-557 (2016).</li><li>Hamburger, V., Hamilton, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+series+of+normal+stages+in+the+development+of+the+chick+embryo.">A series of normal stages in the development of the chick embryo.</a> Dev Dynam. 195 (4), 231-272 (1951).</li><li>Ho, J. W. K., 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=Comparative+analysis+of+metazoan+chromatin+organization.">Comparative analysis of metazoan chromatin organization.</a> Nature. 512 (7515), 449-452 (2014).</li><li>Calo, E., Wysocka, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modification+of+enhancer+chromatin:+what,+how,+and+why?.">Modification of enhancer chromatin: what, how, and why?.</a> Mol Cell. 49 (5), 825-837 (2013).</li><li>Spitz, F., Furlong, E. E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcription+factors:+from+enhancer+binding+to+developmental+control.">Transcription factors: from enhancer binding to developmental control.</a> Nat Rev Genetics. 13 (9), 613-626 (2012).</li></ol>

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, ...

The overall goal of this procedure is to investigate the binding profiles of different histone modifications, using low-abundance embryonic samples in order to improve the functional annotation of vertebrate genomes. This method can help answer key questions in the developmental biology field such as, which are the key enhancers and genes defining the identity of a particular embryonic tissue. The main advantages of this techniques are that it requires a limited amount of particular material and it can also be used for both local specific and genome wide analysis.Though this method can provide insights into transcription regulation or cellular heterogeneity with the embryonic tissues, it can also be applied to other systems such as, patent samples. To obtain stage HH19, chicken embryos for this experiment, incubate fertile white Leghorn hen eggs in horizontal orientation at 37 degrees celsius and 80%humidity for three days. To start isolating the HH19 embryos, make them accessible by extracting three milliliters of albumin with a 10 millimeter syringe to lower the blastoderm.In order to remove extra embryonic membranes, use fine scissors to make a small opening in the eye. Add one milliliter of lock solution. With the help of a bended needle, add 0.5 milliliters of Indian black ink.Use fine surgical scissors and forceps to cut off the extra embryonic membrane that surrounds the embryo. Then, transfer the embryo with a perforated spoon to a 4.5 centimeter petri dish containing 20 milliliters of PBS solution. Working on ice under a stereo microscope, use fine scissors and forceps to dissect and discard the amnion and the remaining parts of extra embryonic membrane.Then, cut the transverse spinal neuro tube or SNT segment at the brachial level of the embryo. Extend the dissection caudally into the thoracic region to isolate the SNT. To finish, use forceps to remove the tissues that laterally and ventrally surround the SNT.After isolating SNTs, immerse each segment in a 3.5 centimeter petri dish containing 37 degree celsius warm trypsin. When loosening of the non-neuro tissues around the SNT is visible under a stereo microscope, transfer the samples into cold 1x PBS. To stop the trypsinization, transfer the samples into a new dish with cold DMEM containing 10%FBS.Use forceps to manually remove the remaining mesenchymal and ectodermal tissues from the SNT. Transfer this clean SNT section to a 1.5 milliliter tube and flash freeze it in liquid nitrogen. Next, homogenize the tissue according to the text protocol.Add 13.5 microliters of 37%formaldehyde and incubate at room temperature on a rotator for 15 minutes. To quench the formaldehyde, add 25 microliters of 2.5 molar glycine to the tube and incubate at room temperature on a rotator for 10 minutes. Centrifuge the tube and then, wash the pellet according to the text protocol.After crosslinking, re-suspend the pellet in 300 microliters of ice cold, complete lysis buffer by pipetting. Incubate the samples at four degrees celsius on a rocking platform for 10 minutes. Next, sonicate the samples at four degrees celsius.After sonication, centrifuge the samples at 16, 000 x G at four degrees celsius for 10 minutes. Transfer the supernatant or lysate to a fresh 1.5 milliliter tube and discard the cellular debris pellet. Dilute the lysate according to the text protocol.Then, keep a small aliquot of each sample as input control and freeze at 20 degrees celsius. Incubate the remaining samples that will be subjected to chromatin precipitation or chip with appropriate antibodies according to the text protocol. Then, add 300 microliters of antibody bound chromatin to previously washed magnetic beads.Invert the tubes to mix the samples. To bind the antibodies to the beads, place the tubes on a tube rotator and rotate vertically at four degree celsius for a minimum of four hours. To wash the chromatin bound beads, add one milliliter of ice cold RIPA wash buffer to the tube kept on ice and mix by inverting or flicking the tube.After placing the tube into the magnetic holder at room temperature, wait for the beads to settle on the side. Pour off the clear liquid and repeat this wash three more times. After adding one milliliter of TE 50 millimolar sodium chloride to the tube, transfer the chromatin bound beads in this solution to a fresh 1.5 millimeter microcentrifuge tube.Place the tube into the magnetic holder and when the beads have settled, pour off the liquid. Next, centrifuge the beads at 900 x G at four degrees celsius for three minutes in a pre-cooled centrifuge. After the beads have been settled in the magnetic holder, remove all remaining TE using a gel loading tip.Working at room temperature, add 210 microliters of elution buffer to the beads and re-suspend by flicking. Incubate the tube in a pre-warmed heat block at 65 degree celsius for 15 minutes, while shaking. After incubation, centrifuge the tubes with the beads at 16, 000 x G at room temperature, for one minute.Once the beads have settled in the magnetic holder, transfer the supernatant to a fresh microcentrifuge tube. Thaw the previously frozen input control sample from 20 degrees celsius to room temperature. Add 90 microliters of elution buffer to the sample and mix by briefly vortexing.To reverse the cross-links, incubate the chip and control samples at 65 degrees celsius overnight. Working at room temperature, add one volume of TE buffer per tube and invert to mix. To digest the RNA, add RNAse A to the control and chip samples to a final concentration of 0.2 milligrams per milliliter and invert the tubes to mix.Incubate the tubes in a pre-warmed heat block at 37 degrees celsius for two hours. To digest the protein for the subsequent DNA purification, add protease K to a final concentration of 0.2 milligrams per milliliters to the tubes and invert the tubes to mix. Incubate the tubes in a pre-warmed heat block at 55 degrees celsius for two hours.Extract and purify the DNA according to the supplementary materials. This DNA can now be used for quantitative PCR and chip seek library preparation. Sonication efficiency essential for a successful chip is confirmed by agarose gel electrophoresis of the input control samples.In this example, using chicken spinal neural tube or SNT sections, 11 sonication cycles were used to obtain an optimal fragment size ranging from 200 to 500 base pairs. Chipped DNA was analyzed by quantitative PCR to measure the enrichment levels of activating and repressive histone marks around the promoter regions of genes that are active and inactive in the chicken SNT. This shows that it is possible to evaluate the chipped quality by quantifying only a few low side without losing much DNA for further analysis.After chip seek libraries were prepared in sequence, a representative locust is shown for H3K27 tri methylation and H3K4 tri methylation chip seek data generated in chicken SNT. Similar chip seek profiles were also successfully generated in different chicken embryonic tissues, such as maxillary prominences and stage HH3 embryos. This demonstrates that here presented, chip protocol can be used to generate epigenomic profiles from limited amounts of various embryonic tissues.By using this protocol to generate the histone modification profiles in an embryonic tissue, it is important to remember that signals will come from all different cell types present in such tissue. Following this protocol and using more starting biological material, it should be possible to investigate the binding profiles of other proteins involved in transcriptional regulation, such as, transcription factors, co-activators or RNA polymerase 2 sub units. Once established, these protocols will enable researchers in the field of developmental biology or medical genetics to improve the functional alteration of vertebrate genomes and to gain important insights into the molecular basis of myogenesis, evolution and human disease.

chromatin-immunoprecipitation-chip-protocol-for-low-abundance

Research

JoVE Journal

Genetics

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 ...

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 ...

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 ...

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 ...

Genome-wide Analysis of Histone Modifications Distribution using the Chromatin Immunoprecipitation Sequencing Method in Magnaporthe oryzae

Chromatin immunoprecipitation sequencing (ChIP-seq) is a powerful and widely used molecular technique for mapping whole genome locations of transcription factors (TFs), chromatin regulators, and histone modifications, as well as detecting entire genomes for uncovering TF binding patterns and histone posttranslational modifications. Chromatin-modifying activities, such as histone methylation, are often recruited to specific gene regulatory sequences, causing localized changes in chromatin structures and resulting in specific transcriptional effects. The rice blast is a devastating fungal disease on rice throughout the world and is a model system for studying fungus-plant interaction. However, the molecular mechanisms in how the histone modifications regulate their virulence genes in Magnaporthe oryzae remain elusive. More researchers need to use ChIP-seq to study how histone epigenetic modification regulates their target genes. ChIP-seq is also widely used to study the interaction between protein and DNA in animals and plants, but it is less used in the field of plant pathology and has not been well developed. In this paper, we describe the experimental process and operation method of ChIP-seq to identify the genome-wide distribution of histone methylation (such as H3K4me3) that binds to the functional target genes in M. oryzae. Here, we present a protocol to analyze the genome-wide distribution of histone modifications, which can identify new target genes in the pathogenesis of M. oryzae and other filamentous fungi.

Genome-wide Analysis of Histone Modifications Distribution using the Chromatin Immunoprecipitation Sequencing Method in Magnaporthe oryzae

Here, we present a protocol to analyze the genome-wide distribution of histone modifications, which can identify new target genes in the pathogenesis of M. oryzae and other filamentous fungi.

Chromatin immunoprecipitation sequencing (ChIP-seq) is a powerful and widely used molecular technique for mapping whole genome locations of transcription ...