Name: high-resolution mapping of protein-dna interactions in mouse stem cell-derived neurons using chromatin immunoprecipitation-exonuclease (chip-exo)
Uploaded: 2020-08-14T16:00:00
Description: Watch this Scientific Journal Video about High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease ChIP-Exo at JoVE.com

我们感谢 Rhee 实验室的成员分享未发布的数据和宝贵的讨论。这项工作得到了加拿大自然科学和工程研究理事会（NSERC）赠款RGPIN-2018-06404（H.R.）的支持。

注：建议自动提取蒸馏和去离子化水（ddH2O）制作缓冲液和反应大师混合。第1-4节描述细胞裂解和声波化，第5-7节描述色素免疫沉淀（ChIP），第8-11节描述珠子上的酶反应，第12节和第13节描述ChIP精英和DNA纯化，第14-19节描述库准备。
1. 收获和交叉链接细胞
<ol><li>将小鼠 ES 细胞分化为后线粒体神经元后，在收获的细胞中加入 11% 甲醛，最终浓度为 1%（v/v）...

<ol>
	<li>Johnson, D. S., Mortazavi, A., Myers, R. M., Wold, B. <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+mapping+of+in+vivo+protein-DNA+interactions.">Genome-wide mapping of in vivo protein-DNA interactions.</a> Science. 316 (5830), 1497-1502 (2007).</li><li>Patten, D. K., Corleone, G., Magnani, L., A, J. e. l. t. s. c. h., Rots, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenome+Editing:+Methods+and+Protocols.">Epigenome Editing: Methods and Protocols.</a> Methods in Molecular Biology. 1767, 271-288 (2018).</li><li>Serandour, A. A., Brown, G. D., Cohen, J. D., Carroll, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+an+Illumina-based+ChIP-exonuclease+method+provides+insight+into+FoxA1-DNA+binding+properties.">Development of an Illumina-based ChIP-exonuclease method provides insight into FoxA1-DNA binding properties.</a> Genome Biology. 14 (12), 147 (2013).</li><li>Rhee, H. S., Pugh, B. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comprehensive+genome-wide+protein-DNA+interactions+detected+at+single-nucleotide+resolution.">Comprehensive genome-wide protein-DNA interactions detected at single-nucleotide resolution.</a> Cell. 147 (6), 1408-1419 (2011).</li><li>Rhee, H. S., Pugh, B. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ChIP-exo+method+for+identifying+genomic+location+of+DNA-binding+proteins+with+near-single-nucleotide+accuracy.">ChIP-exo method for identifying genomic location of DNA-binding proteins with near-single-nucleotide accuracy.</a> Current Protocols in Molecular Biology. Chapter 21, 21-24 (2012).</li><li>Starick, S. 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=ChIP-exo+signal+associated+with+DNA-binding+motifs+provides+insight+into+the+genomic+binding+of+the+glucocorticoid+receptor+and+cooperating+transcription+factors.">ChIP-exo signal associated with DNA-binding motifs provides insight into the genomic binding of the glucocorticoid receptor and cooperating transcription factors.</a> Genome Research. 25 (6), 825-835 (2015).</li><li>Han, G. C., 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+Organization+of+GATA1+and+TAL1+Determined+at+High+Resolution.">Genome-Wide Organization of GATA1 and TAL1 Determined at High Resolution.</a> Molecular and Cellular Biology. 36 (1), 157-172 (2016).</li><li>Rhee, H. S., Bataille, A. R., Zhang, L. Y., Pugh, B. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subnucleosomal+Structures+and+Nucleosome+Asymmetry+across+a+Genome.">Subnucleosomal Structures and Nucleosome Asymmetry across a Genome.</a> Cell. 159 (6), 1377-1388 (2014).</li><li>Rhee, H. S., Pugh, B. F. <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+structure+and+organization+of+eukaryotic+pre-initiation+complexes.">Genome-wide structure and organization of eukaryotic pre-initiation complexes.</a> Nature. 483 (7389), 295-301 (2012).</li><li>Zhou, X. F., Yan, Q., Wang, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deciphering+the+regulon+of+a+GntR+family+regulator+via+transcriptome+and+ChIP-exo+analyses+and+its+contribution+to+virulence+in+Xanthomonas+citri.">Deciphering the regulon of a GntR family regulator via transcriptome and ChIP-exo analyses and its contribution to virulence in Xanthomonas citri.</a> Molecular Plant Pathology. 18 (2), 249-262 (2017).</li><li>Kim, 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=Systems+assessment+of+transcriptional+regulation+on+central+carbon+metabolism+by+Cra+and+CRP.">Systems assessment of transcriptional regulation on central carbon metabolism by Cra and CRP.</a> Nucleic Acids Research. 46 (6), 2901-2917 (2018).</li><li>Niu, 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=In+vivo+genome-wide+binding+interactions+of+mouse+and+human+constitutive+androstane+receptors+reveal+novel+gene+targets.">In vivo genome-wide binding interactions of mouse and human constitutive androstane receptors reveal novel gene targets.</a> Nucleic Acids Research. 46 (16), 8385-8403 (2018).</li><li>Uuskula-Reimand, L., 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=Topoisomerase+II+beta+interacts+with+cohesin+and+CTCF+at+topological+domain+borders.">Topoisomerase II beta interacts with cohesin and CTCF at topological domain borders.</a> Genome Biology. 17, (2016).</li><li>Rhee, H. S., 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=Expression+of+Terminal+Effector+Genes+in+Mammalian+Neurons+Is+Maintained+by+a+Dynamic+Relay+of+Transient+Enhancers.">Expression of Terminal Effector Genes in Mammalian Neurons Is Maintained by a Dynamic Relay of Transient Enhancers.</a> Neuron. 92 (6), 1252-1265 (2016).</li><li>Pugh, B. F., Venters, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genomic+Organization+of+Human+Transcription+Initiation+Complexes.">Genomic Organization of Human Transcription Initiation Complexes.</a> Plos One. 11 (2), (2016).</li><li>Wang, S., 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=ATF4+Gene+Network+Mediates+Cellular+Response+to+the+Anticancer+PAD+Inhibitor+YW3-56+in+Triple-Negative+Breast+Cancer+Cells.">ATF4 Gene Network Mediates Cellular Response to the Anticancer PAD Inhibitor YW3-56 in Triple-Negative Breast Cancer Cells.</a> Molecular Cancer Therapeutics. 14 (4), 877-888 (2015).</li><li>Barfeld, S. J., 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=c-Myc+Antagonises+the+Transcriptional+Activity+of+the+Androgen+Receptor+in+Prostate+Cancer+Affecting+Key+Gene+Networks.">c-Myc Antagonises the Transcriptional Activity of the Androgen Receptor in Prostate Cancer Affecting Key Gene Networks.</a> Ebiomedicine. 18, 83-93 (2017).</li><li>McHaourab, Z. F., Perreault, A. A., Venters, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ChIP-seq+and+ChIP-exo+profiling+of+Pol+II,+H2A.Z,+and+H3K4me3+in+human+K562+cells.">ChIP-seq and ChIP-exo profiling of Pol II, H2A.Z, and H3K4me3 in human K562 cells.</a> Scientific Data. 5, 180030 (2018).</li><li>Perreault, A. A., Sprunger, D. M., Venters, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetic+and+transcriptional+profiling+of+triple+negative+breast+cancer.">Epigenetic and transcriptional profiling of triple negative breast cancer.</a> Scientific Data. 6, 190033 (2019).</li><li>Rossi, M. J., Lai, W. K. M., Pugh, B. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simplified+ChIP-exo+assays.">Simplified ChIP-exo assays.</a> Nature Communications. 9 (1), 2842 (2018).</li><li>Perreault, A. A., Venters, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ChIP-exo+Method:+Identifying+Protein-DNA+Interactions+with+Near+Base+Pair+Precision.">The ChIP-exo Method: Identifying Protein-DNA Interactions with Near Base Pair Precision.</a> Journal of Visualized Experiments. (118), (2016).</li><li>Jezek, M., Jacques, A., Jaiswal, D., Green, 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=Chromatin+Immunoprecipitation+(ChIP)+of+Histone+Modifications+from+Saccharomyces+cerevisiae.">Chromatin Immunoprecipitation (ChIP) of Histone Modifications from Saccharomyces cerevisiae.</a> Journal of Visualized Experiments. (130), (2017).</li><li>Terranova, C., 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=An+Integrated+Platform+for+Genome-wide+Mapping+of+Chromatin+States+Using+High-throughput+ChIP-sequencing+in+Tumor+Tissues.">An Integrated Platform for Genome-wide Mapping of Chromatin States Using High-throughput ChIP-sequencing in Tumor Tissues.</a> Journal of Visualized Experiments. (134), (2018).</li><li>Pchelintsev, N. A., Adams, P. D., Nelson, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Parameters+for+Efficient+Sonication+and+Improved+Chromatin+Immunoprecipitation+of+High+Molecular+Weight+Proteins.">Critical Parameters for Efficient Sonication and Improved Chromatin Immunoprecipitation of High Molecular Weight Proteins.</a> PLos One. 11 (1), (2016).</li><li>Yamada, N., Lai, W. K. M., Farrell, N., Pugh, B. F., Mahony, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterizing+protein-DNA+binding+event+subtypes+in+ChIP-exo+data.">Characterizing protein-DNA binding event subtypes in ChIP-exo data.</a> Bioinformatics. 35 (6), 903-913 (2019).</li><li>Yen, K., Vinayachandran, V., Pugh, B. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SWR-C+and+INO80+chromatin+remodelers+recognize+nucleosome-free+regions+near++1+nucleosomes.">SWR-C and INO80 chromatin remodelers recognize nucleosome-free regions near +1 nucleosomes.</a> Cell. 154 (6), 1246-1256 (2013).</li><li>Vinayachandran, V., 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=Widespread+and+precise+reprogramming+of+yeast+protein-genome+interactions+in+response+to+heat+shock.">Widespread and precise reprogramming of yeast protein-genome interactions in response to heat shock.</a> Genome Research. , (2018).</li></ol>

在此协议中，ChIP随后的外核酶消化用于获取DNA库，以超高映射分辨率识别哺乳动物细胞中的蛋白质-DNA相互作用。许多变量有助于ChIP-exo实验的质量。关键的实验参数包括抗体的质量、声波的优化以及LM-PCR周期的数量。这些关键的实验参数也是可以限制ChIP-exo实验，并将在下面讨论。
在任何 ChIP 协议中，抗体质量都是最重要的考虑因素之一。建议使用ChIP级抗体。在执行 ChIP-exo ...

蛋白质与DNA相互作用的位置提供了对基因调控机制的洞察。色素免疫沉淀加上高通量测序（ChIP-seq）已经使用了十年来研究活细胞1、2的全基因组蛋白质-DNA相互作用。然而，ChIP-seq方法受DNA片段的异质性和未绑定的DNA污染的限制，导致低映射分辨率、误报、未接听电话和非特定背景信号。ChIP与外核酶消化（ChIP-exo）的结合，通过将ChIPDNA修剪到蛋白质-DNA交叉连接点，提供接近碱基对分辨率和低背景信号3、4、5，从而改进了ChIP-seq方法。ChIP-exo 提供的大大改进的映射分辨率和低背景使整个基因组中能够确定准确和全面的蛋白质-DNA 结合位置。ChIP-exo 能够揭示功能上独特的 DNA 结合图案、转录因子 （TF） 和特定基因组结合位置的多个蛋白质-DNA 交叉链接位点之间的协同相互作用，其他基因组映射方法3、4、6、7无法检测。
ChIP-exo最初用于初露头角的酵母，以检查TF的序列特异性DNA结合，研究转录启动前复合物的精确组织，以及整个基因组4、8、9的单个组酮的亚核体结构。自2011年推出以来，ChIP-exo已成功地用于许多其他生物体，包括细菌、小鼠和人类细胞7、10、11、12、13、14、15、16、17。2016 年，Rhee 等人14首次在哺乳动物神经元中使用 ChIP-exo 来了解在编程 TF Lhx3 降低调节后神经元基因表达是如何维持的，该编程与另一个编程 TF Isl1 形成了一个异质复合体。这项研究表明，在没有Lhx3的情况下，Isl1被招募到受Onecut1 TF约束的新神经元增强剂中，以维持神经元效应基因的基因表达。在这项研究中，ChIP-exo揭示了多个TF如何以接近核苷酸制图分辨率的组合方式动态识别细胞类型和细胞阶段特异性DNA调控元素。其他研究还使用ChIP-exo方法来理解其他哺乳动物细胞系中蛋白质和DNA之间的相互作用。Han等人利用ChIP-exo使用ChIP-exo来研究小鼠红细胞中GATA1和TAL1 TF的全基因组组织。这项研究发现，TAL1是直接招募到DNA，而不是间接通过蛋白质-蛋白质相互作用与GATA1在整个红细胞分化。最近的研究还利用ChIP-exo对CTCF、RNA聚合酶II和平石标记的全基因组结合位置进行剖析，以研究人类细胞系18、19的表观和转录机制。
有几个版本的ChIP-exo协议可用3，5，20。然而，对于不熟悉下一代测序库准备的研究，这些 ChIP-exo 协议很难遵循。ChIP-exo 协议的优秀版本发布时附有易于遵循的说明和视频21，但包含许多酶步骤，需要大量时间才能完成。在这里，我们报告了包含减少酶步骤和潜伏时间的ChIP-exo协议的新版本，以及每个酶步骤21的解释。使用末端预制酶，将末端修复和 dA 尾部反应一步一步地组合在一起。使用夹带增强剂将索引和通用适配器连体步骤的潜伏时间从 2 小时缩短到 15 分钟。删除上一个 ChIP-exo 协议中描述的索引适配器连结步骤后的激酶反应。相反，在寡头DNA合成过程中，磷酸盐组被添加到索引适配器（表1）的5'端之一，这将用于羊田外核酶消化步骤。虽然以前的 ChIP-exo 协议使用 RecJf外核酶消化来消除单链 DNA 污染物，但此消化步骤在这里被删除，因为它对 ChIP-exo 库的质量不至关重要。此外，为了在ChIP分离后净化反向交叉DNA，使用磁珠净化方法代替苯酚：氯仿：异酰醇（PCIA）提取方法。这缩短了DNA提取的潜伏时间。重要的是，它去除索引适配器结对过程中形成的大多数适配器调色器，这可能会影响结对介质 PCR 的效率。
此处提出的ChIP-exo协议进行了优化，用于检测与小鼠胚胎干细胞（ES）细胞分化的哺乳动物神经元的精确蛋白质-DNA相互作用。简言之，收获和交叉链接的神经元细胞被裂解，让色素暴露在声波中，然后进行声波化，从而获得适当大小的DNA片段（图1）。然后，抗体涂层珠子用于有选择地免疫沉淀支离破碎的可溶性色素到感兴趣的蛋白质。当免疫沉淀DNA仍在珠子上时，进行末修复、测序适配器的结对、填充反应和5'至3'lambda外核酶消化步骤。外核酶消化步骤使ChIP-exo具有超高分辨率和高信号噪声比。Lambda 外核酶将免疫沉淀的 DNA 从交叉连接部位修剪出几个碱基对 （bp），从而导致污染的 DNA 降解。外核酶处理的ChIP DNA从抗体涂层珠子中分离出，蛋白质-DNA交叉链路被逆转，蛋白质退化。脱氧核糖核酸被提取并去自然到单链ChIPDNA，然后引物退化和扩展，使双链DNA（dsDNA）。接下来，执行将通用适配器与外核酶处理末端的连结。由此产生的DNA被纯化，然后PCR放大，凝胶纯化，并接受下一代测序。
ChIP-exo 协议比 ChIP-seq 协议长，但在技术上并不十分具有挑战性。任何成功的免疫沉淀的ChIPDNA都可以接受ChIP-exo，并具有几个额外的酶步骤。ChIP-exo在基因组结合位点方面的显著优势，如超高映射分辨率、减少背景信号、减少误报和阴性，超过了时间成本。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >Agarose, UltraPure</td>
			<td >Invitrogen</td>
			<td >16500</td>
			<td >Checking Sonication (Section 4.3.6) and Gel Purification of LM-PCR Amplified DNA (Section 19.1)</td>
		</tr>
		<tr >
			<td >Albumin, Bovine Serum (BSA), Protease Free, Heat Shock Isolation, Min. 98%</td>
			<td >BioShop</td>
			<td >ALB003</td>
			<td >Blocking Solution</td>
		</tr>
		<tr >
			<td >Antibody against Isl1</td>
			<td >DSHB</td>
			<td >39.3F7</td>
			<td >Antibody incuation with beads (Section 5.6)</td>
		</tr>
		<tr >
			<td >Bioruptor Pico&#160;</td>
			<td >Diagenode</td>
			<td >B01060010</td>
			<td >Sonicating Chromatin (Section 3.3)</td>
		</tr>
		<tr >
			<td >Bovine serum albumin (BSA), Molecular Biology Grade</td>
			<td >New England BioLabs</td>
			<td >B9000S</td>
			<td >Fill-in Reaction on Beads (Section 10.2) and Denaturing, Primer Annealing and Primer Extension (Section 14.2)</td>
		</tr>
		<tr >
			<td >Centrifuge 5424 R</td>
			<td >Eppendorf</td>
			<td >5404000138</td>
			<td >Sonicating Chromatin (Section 3.5), Checking Sonication (Section 4.3.1, 4.3.3 and 4.3.4)</td>
		</tr>
		<tr >
			<td >Centrifuge 5804 R</td>
			<td >Eppendorf</td>
			<td >22623508</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.3), Cell lysis (Section 2.2 and 2.3), Sonicating Chromatin (Section 3.1)</td>
		</tr>
		<tr >
			<td >cOmplete, Mini, EDTA-free Protease Inhibitor Cocktail</td>
			<td >Roche</td>
			<td >4693159001</td>
			<td >Added to all buffers, except Proteinase K buffer and ChIP Elution buffer</td>
		</tr>
		<tr >
			<td >dATP Solution</td>
			<td >New England BioLabs</td>
			<td >N0440S</td>
			<td >dA-Tailing Reaction (Section 15.1)</td>
		</tr>
		<tr >
			<td >Deoxycholic Acid Sodium Salt</td>
			<td >fisher scientific</td>
			<td >BP349</td>
			<td >Lysis Buffer 3, High Salt Wash Buffer and LiCl Wash Buffer</td>
		</tr>
		<tr >
			<td >dNTP Mix, Molecular Biology Grade</td>
			<td >Thermo Scientific</td>
			<td >R0192</td>
			<td >Fill-in Reaction on Beads (Section 10.2) and Denaturing, Primer Annealing and Primer Extension (Section 14.2)</td>
		</tr>
		<tr >
			<td >DreamTaq Green PCR Master Mix, 2x&#160;</td>
			<td >Thermo Scientific</td>
			<td >K1081</td>
			<td >Ligation-Mediated PCR (Section 18.1)</td>
		</tr>
		<tr >
			<td >EDTA, 0.5 M, Sterile Solution, pH 8.0</td>
			<td >BioShop</td>
			<td >EDT111</td>
			<td >Lysis Buffer 1-3, Checking Sonication (Section 4.1), High Salt Wash Buffer, LiCl Wash Buffer and ChIP Elution Buffer</td>
		</tr>
		<tr >
			<td >Ethyl Alcohol Anhydrous, 100%</td>
			<td >Commercial alcohols</td>
			<td >P006EAAN</td>
			<td >Checking Sonication (Section 4.3.3)</td>
		</tr>
		<tr >
			<td >Formaldehyde, 36.5-38%, contains 10-15% methanol</td>
			<td >Sigma</td>
			<td >F8775</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.1)</td>
		</tr>
		<tr >
			<td >Glycerol, Reagent Grade, min 99.5%</td>
			<td >BioShop</td>
			<td >GLY002</td>
			<td >Lysis Buffer 1</td>
		</tr>
		<tr >
			<td >Glycine, Biotechnology Grade, min. 99%</td>
			<td >BioShop</td>
			<td >GLN001</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.2)</td>
		</tr>
		<tr >
			<td >Glycogen, RNA Grade</td>
			<td >Thermo Scientific</td>
			<td >R0551</td>
			<td >Checking Sonication (Section 4.3.3)</td>
		</tr>
		<tr >
			<td >HEPES, 1 M Sterile-filtered Solution, pH 7.3&#160;</td>
			<td >BioShop</td>
			<td >HEP003</td>
			<td >Lysis Buffer 1, High Salt Wash Buffer</td>
		</tr>
		<tr >
			<td >Klenow Fragment (3-&#62;5 exo-)</td>
			<td >New England BioLabs</td>
			<td >M0212S</td>
			<td >dA-Tailing Reaction (Section 15.1)</td>
		</tr>
		<tr >
			<td >Lambda exonuclease</td>
			<td >New England BioLabs</td>
			<td >M0262S</td>
			<td >Lambda Exonuclease Digestion on Beads (Section 11.2)</td>
		</tr>
		<tr >
			<td >Ligase Enhancer</td>
			<td >New England BioLabs</td>
			<td >E7645S</td>
			<td >NEBNext Ultra II DNA Library Kit. Index Adapter Ligation on Beads (Section 9.1) and Universal Adapter Ligation (Section 16.1)</td>
		</tr>
		<tr >
			<td >Ligase Master Mix</td>
			<td >New England BioLabs</td>
			<td >E7645S</td>
			<td >NEBNext Ultra II DNA Library Kit. Index Adapter Ligation on Beads (Section 9.1) and Universal Adapter Ligation (Section 16.1)</td>
		</tr>
		<tr >
			<td >Lithium Chloride (LiCl), Reagent grade</td>
			<td >Bioshop</td>
			<td >LIT704</td>
			<td >LiCl Wash Buffer</td>
		</tr>
		<tr >
			<td >Magnetic beads for ChIP (Dynabeads Protein G)</td>
			<td >Dynabeads Protein G (magnetic beads for ChIP)</td>
			<td >Dynabeads Protein G (magnetic beads for ChIP)</td>
			<td >Antibody incubation with beads (Section 5)</td>
		</tr>
		<tr >
			<td >Magnetic beads for DNA purification (AMPure XP Beads)</td>
			<td >Beckman Coulter</td>
			<td >A63880</td>
			<td >DNA Extraction (Section 13.3) and DNA Clean-up (Section 17.1)</td>
		</tr>
		<tr >
			<td >Magnetic rack (DynaMag-2 Magnet)</td>
			<td >Invitrogen</td>
			<td >12321D</td>
			<td >Used in many steps in Sections: 5 - 11, 13</td>
		</tr>
		<tr >
			<td >MinElute Gel Extraction Kit</td>
			<td >Qiagen&#160;</td>
			<td >28604</td>
			<td >Gel Purification of PCR Amplified DNA (Section 19.2)</td>
		</tr>
		<tr >
			<td >N-Lauroylsarcosine sodium salt solution, 30% aqueous solution, &#8805;97.0% (HPLC)</td>
			<td >Sigma</td>
			<td >61747</td>
			<td >Lysis Buffer 3</td>
		</tr>
		<tr >
			<td >Octylphenol Ethoxylate (IGEPAL CA630)</td>
			<td >BioShop</td>
			<td >NON999</td>
			<td >Lysis Buffer 1 and LiCl Wash Buffer</td>
		</tr>
		<tr >
			<td >Phenol:Chloroform:Isoamyl Alcohol, Biotechnology Grade (25:24:1)</td>
			<td >BioShop</td>
			<td >PHE512</td>
			<td >Checking Sonication (Section 4.3.1)</td>
		</tr>
		<tr >
			<td >phi29 DNA Polymerase</td>
			<td >New England BioLabs</td>
			<td >M0269L</td>
			<td >Fill-in Reaction on Beads (Section 10.2) and Denaturing, Primer Annealing and Primer Extension (Section 14.3 and 14.4)</td>
		</tr>
		<tr >
			<td >Phosphate-Buffered Saline (PBS), 1x&#160;</td>
			<td >Corning</td>
			<td >21040CV</td>
			<td >Harvest, cross-linking and freezing cells (Section 1.3) and Sonicating Chromatin (Section 3.1), Antibody incuation with beads (Section 5.1)</td>
		</tr>
		<tr >
			<td >PowerPac Basic Power Supply</td>
			<td >BioRad</td>
			<td >1645050</td>
			<td >Checking Sonication (Section 4.3.6) and Gel Purification of LM-PCR Amplified DNA (Section 19.1)</td>
		</tr>
		<tr >
			<td >ProFlex PCR System</td>
			<td >Applied Biosystems</td>
			<td >ProFlex PCR System</td>
			<td >Used in Sections: 14.2, 14.4, 15.2, 16.2 and 18.2</td>
		</tr>
		<tr >
			<td >Protein LoBind Tube, 2.0 mL&#160;</td>
			<td >Eppendorf</td>
			<td >22431102</td>
			<td >Antibody Incubation with Beads (Section 5.2) and Chromatin Immunoprecipitation (Section 6.3)</td>
		</tr>
		<tr >
			<td >Proteinase K Solution, RNA Grade</td>
			<td >Invitrogen</td>
			<td >25530049</td>
			<td >Checking Sonication (Section 4.2) and Elution and Reverse Crosslinking (Section 12.3)</td>
		</tr>
		<tr >
			<td >Qubit 4.0 Fluorometer</td>
			<td >Invitrogen</td>
			<td >Q33226</td>
			<td >Gel Purification of PCR Amplified DNA (Section 19.3)</td>
		</tr>
		<tr >
			<td >Quibit dsDNA BR assay kit</td>
			<td >Invitrogen</td>
			<td >Q32853</td>
			<td >Gel Purification of PCR Amplified DNA (Section 19.3)</td>
		</tr>
		<tr >
			<td >Rnase A, Dnase and Protease-free</td>
			<td >Thermo Scientific</td>
			<td >EN0531</td>
			<td >Checking Sonication (Section 4.3.2) and DNA Extraction (Section 13.2)</td>
		</tr>
		<tr >
			<td >Sodium chloride (NaCl), BioReagent&#160;</td>
			<td >Sigma</td>
			<td >S5886</td>
			<td >Lysis Buffer 1-3, High Salt Wash Buffer</td>
		</tr>
		<tr >
			<td >Sodium Dodecyl Sulfate (SDS), Electrophoresis Grade</td>
			<td >BioShop</td>
			<td >SDS001</td>
			<td >Checking Sonication (Section 4.1), High Salt Wash Buffer and ChIP Elution Buffer</td>
		</tr>
		<tr >
			<td >Sonication beads and 15 mL Bioruptor Tubes</td>
			<td >Diagenode</td>
			<td >C01020031</td>
			<td >Sonicating Chromatin (Section 3.1 and 3.2)</td>
		</tr>
		<tr >
			<td >ThermoMixer F1.5&#160;</td>
			<td >Eppendorf</td>
			<td >5384000020</td>
			<td >Section 4.2, 4.3.2, 4.3.5, 8.2, 9.2, 10.3, 11.2, 12.2, 12.3, 13.2 and 16.2</td>
		</tr>
		<tr >
			<td >Trizma hydrochloride solution (Tris-HCl), BioPerformance Certified, 1 M, pH 7.4</td>
			<td >Sigma</td>
			<td >T2194</td>
			<td >10 mM Tris-HCl Buffer</td>
		</tr>
		<tr >
			<td >Trizma hydrochloride solution (Tris-HCl), BioPerformance Certified, 1 M, pH 8.0</td>
			<td >Sigma</td>
			<td >T2694</td>
			<td >Lysis Buffer 2, Lysis Buffer 3, Checking Sonication (Section 4.1), LiCl Wash Buffer and ChIP Elution Buffer</td>
		</tr>
		<tr >
			<td >Ultra II End Repair/dA-Tailing Module (24 rxn -&#62; 120 rxn)</td>
			<td >New England BioLabs</td>
			<td >E7546S</td>
			<td >End Prep Reaction mix and End Prep Enzyme mix. End-repair and dA-Tailing Reaction on Beads (Section 8.2)</td>
		</tr>
		<tr >
			<td >VWR Mini Tube Rocker, Variable Speed</td>
			<td >VWR</td>
			<td >10159-752</td>
			<td >Used in many steps in sections: 1, 2, 5, 6 and 7</td>
		</tr>
		<tr >
			<td >2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol, Triton X-100, Reagent Grade</td>
			<td >BioShop</td>
			<td >TRX506</td>
			<td >Lysis Buffer 1, Sonicating Chromatin (Section 3.4) and High Salt Wash Buffer</td>
		</tr>
	</tbody>
</table>

high-resolution mapping of protein-dna interactions in mouse stem cell-derived neurons using chromatin immunoprecipitation-exonuclease (chip-exo)

识别基因组上特定的蛋白质-DNA相互作用对于理解基因调控具有重要意义。色素免疫沉淀与高通量测序（ChIP-seq）广泛用于识别DNA结合蛋白的全基因组结合位置。然而，ChIP-seq方法受其声波DNA片段长度和非特定背景DNA的异质性限制，导致DNA结合位点的制图分辨率低且不确定。为了克服这些限制，ChIP与外核酶消化（ChIP-exo）的结合利用5'到3'外核酶消化来修剪异构大小的免疫沉淀DNA到蛋白质-DNA交叉连接部位。外核酶治疗也消除了非特定背景DNA。图书馆准备的和外核酶消化的DNA可以发送用于高通量测序。ChIP-exo 方法允许近基对映射分辨率，具有更高的检测灵敏度和更小的背景信号。下文描述了哺乳动物细胞和下一代测序的优化 ChIP-exo 协议。

图2A说明了从小鼠ES细胞中分离出来的运动神经元细胞的细胞裂解和声波化后产生的声波结果。声波周期的最佳数量（例如图 2A中的12个周期）在100-400 bp DNA片段中产生强烈的DNA强度。高质量的 ChIP-exo 库基于支离破碎的染色质 DNA 的大小和数量。因此，建议在启动ChIP-exo之前，对每个细胞类型和批次细胞进行声波优化。
<strong class="xfig...

Watch this Scientific Journal Video about High-Resolution Mapping of Protein-DNA Interactions in Mouse Stem Cell-Derived Neurons using Chromatin Immunoprecipitation-Exonuclease ChIP-Exo at JoVE.com

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

精确确定整个基因组中的蛋白质结合位置对于理解基因调控非常重要。在这里，我们描述了一种基因组映射方法，它用外核酶消化（ChIP-exo）处理染色质免疫沉淀DNA，然后进行高通量测序。该方法可检测哺乳动物神经元中具有近碱基对映射分辨率和高信号噪声比的蛋白质-DNA相互作用。

使用色素免疫沉淀-外核酶（ChIP-Exo）对小鼠干细胞衍生神经元中的蛋白质-DNA相互作用进行高分辨率映射

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

The main advantage of our ChIP-exo method is the improved mapping resolution of protein DNA interactions in the cell compared to the conventional chromatin immunoprecipitation method. To prepare protein G magnetic beads for ChIP, mix the magnetic beads until homogeneous. Then add 25 microliters of the magnetic beads to a two milliliter protein low bind tube.Add one milliliter of blocking solution to the beads. Mix well by pipetting, then place the tube on a magnetic rack for one minute. Once the supernatant is clear, remove it.Next, add one milliliter of blocking solution to the beads. Place the tube on a rocking platform at four degrees Celsius and rock for 10 minutes, then briefly spin the tube. Place the tube on the magnetic rack and remove the supernatant.Add 500 microliters of blocking solution to the magnetic beads. Briefly spin the antibody against Islet-1, then add four micrograms of the antibody to the tube containing the magnetic beads. Place the tube containing magnetic beads and Islet-1 antibody on a rocking platform at four degrees Celsius and rock for six to 24 hours.To begin the chromatin immunoprecipitation, wash the antibody-coated beads in one milliliter of blocking solution. Place the tube containing the antibody-coated beads on a rocking platform at four degrees Celsius for five minutes. After briefly spinning, place the tube on a magnetic rack and remove the supernatant.Resuspend the antibody-coated beads in 50 microliters of blocking solution. Add one milliliter of sonicated lysates to the antibody-coated beads, then incubate the sample on a rocking platform at four degrees Celsius overnight. After allowing the sample to incubate overnight, collect liquid from the cap by briefly spinning the tube, then place the tube on a magnetic rack.And after one minute, remove the supernatant carefully with a pipette. Next, perform a series of washes as follows. Add one milliliter of cold wash buffer containing CPI to the sample.Mix the sample on a rocking platform at four degrees Celsius for five minutes. Briefly spin the sample tube, then place on a magnetic rack. After one minute, remove the supernatant with a pipette.For the first enzymatic reaction and repair and DA tailing, add 38 microliters of autoclaved double distilled water to the sample, then add end prep reaction mix and end prep enzyme mix. Mix the contents of the tube by pipetting, then incubate the sample at 20 degrees Celsius for 30 minutes. Next, wash the sample beads with high salt wash buffer, lithium chloride wash buffer, and 10 millimolar Tris hydrogen chloride buffer as described previously.To perform the index adapter ligation, add 27 microliters of cold 10 millimolar Tris hydrogen chloride buffer to the sample. Then add index adapter, ligation enhancer, and ligase master mix. Incubate the sample at 20 degrees Celsius for 15 minutes.Again, wash the sample beads with high salt wash buffer, lithium chloride wash buffer, and 10 millimolar Tris hydrogen chloride buffer. Then add 47 microliters of cold 10 millimolar Tris hydrogen chloride buffer to the sample. To repair the nick in the DNA resulting from the missing phosphodiester bond, add 11.1 microliters of the fill-in mix to the sample.Incubate the sample at 30 degrees Celsius for 20 minutes. After a series of washes, add 50 microliters of cold autoclaved double distilled water to the sample. To digest the ChIP DNA in the five prime to three prime direction, add lambda exonuclease buffer and lambda exonuclease and mix the sample by pipetting.Incubate the sample at 37 degrees Celsius for 30 minutes. After the digestion is complete, repeat the three washes a final time. To elute ChIP sample from the beads, resuspend the sample in 75 microliters of ChIP elution buffer and incubator at 65 degrees Celsius for 15 minutes at 130 times G.Add 2.5 microliters of 20 milligrams per milliliter proteinase K to the sample.Vortex the sample briefly, then incubate overnight at 65 degrees Celsius. Briefly spin the sample and place on a magnetic rack. After one minute, transfer the supernatant to a new 1.5 milliliter tube.Purify and elute the DNA. After purifying the eluted DNA, transfer 16 microliters of the extracted DNA sample to a PCR tube. Add 1.2 microliters of denaturing and primer annealing mix to the sample.Using the program described in table six of the manuscript, denature and anneal primers to the template DNA. Add three microliters of primer extension mix to the sample and run the PCR program described in table seven of the manuscript. Add 4.1 microliters of DA tailing mix to the sample and run the sample using the PCR program in table eight of the manuscript.Then add 21.5 microliters of universal adapter ligation mix to the sample and incubate for 15 minutes at 20 degrees Celsius. Add 29 microliters of LM-PCR mix to the sample, then run the sample using the program from table 10 of the manuscript. Following 18 cycles of LM-PCR, ChIP-exo samples from mouse motor neurons were electrophoresed on a 1.5%agarose gel.The results for ChIP-exo Islet-1 showed amplified DNA libraries around 200 to 400 base pairs indicating that the ChIP-exo libraries were successfully amplified by LM-PCR. The band around 100 base pairs represents artifacts from adapters and PCR primers. The no antibody control demonstrates that non-specific background DNA was digested by the lambda exonuclease treatment.Using ChIP-exo and ChIP-seq, Islet-1 bound locations were identified. The ChIP-exo signal was highly focused at Islet-1 binding sites detecting multiple clustered Islet-1 transcription factor binding patterns. The ChIP-seq signal displayed broader signals indicating that ChIP-exo had higher mapping resolution than ChIP-seq for Islet-1.Multiple transcription factors often bind DNA next to each other as a protein-DNA complex. ChIP-exo allows us to study how multiple transcription factors recognize and regulate target DNA.

Research

JoVE Journal

Genetics

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

Mapping RNA-RNA Interactions Globally Using Biotinylated Psoralen

使用生物素化补骨脂素全球定位RNA-RNA相互作用

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA ...

科研

遗传学

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

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

与ChEC-seq的蛋白质-DNA相互作用的全基因组映射<em&gt;酿酒酵母（Saccharomyces cerevisiae）</em

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

Chromatin Immunoprecipitation (ChIP) in Mouse T-cell Lines

Chromatin Immunoprecipitation ChIP in Mouse T-cell Lines

染色质免疫沉淀（ChIP）在小鼠T细胞系

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

Retroviral Scanning: Mapping MLV Integration Sites to Define Cell-specific Regulatory Regions

逆转录病毒扫描：映射MLV集成站点以定义细胞特异性监管区域

Moloney murine leukemia (MLV) virus-based retroviral vectors integrate predominantly in acetylated enhancers and promoters. For this reason, mLV ...

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

High Resolution Fluorescent In Situ Hybridization in Drosophila Embryos and Tissues Using Tyramide Signal Amplification

高分辨率荧光原位杂交在果蝇胚胎和组织中使用 Tyramide 信号放大

In our efforts to determine the patterns of expression and subcellular localization of Drosophila RNAs on a genome-wide basis, and in a variety of ...

Mapping Genome-wide Accessible Chromatin in Primary Human T Lymphocytes by ATAC-Seq

ATAC 基因组在原发性人类 T 淋巴细胞中的染色体全易接近染色质

Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq) is a method used for the identification of open (accessible) regions ...

Promoter Capture Hi-C: High-resolution, Genome-wide Profiling of Promoter Interactions

启动子捕获高分辨率, 全基因组的启动子交互分析

The three-dimensional organization of the genome is linked to its function. For example, regulatory elements such as transcriptional enhancers control the ...

CRISPR-Mediated Reorganization of Chromatin Loop Structure

CRISPR 的染色质环结构重组

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

High-Resolution Comparison of Bacterial Conjugation Frequencies

细菌结合频率的高分辨率比较

Bacterial conjugation is an important step in the horizontal transfer of antibiotic resistance genes via a conjugative DNA element. In-depth comparisons ...

Chromatin Immunoprecipitation Assay Using Micrococcal Nucleases in Mammalian Cells

使用哺乳动物细胞中的微球菌核酸酶进行染色质免疫沉淀测定

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