a.1 得到加拿大卫生研究院的加拿大研究生奖学金的支持。这项工作得到了来自不列颠哥伦比亚省和加拿大卫生研究院 (CIHR-120589) 的赠款的支持, 这是加拿大的遗传学、环境和健康研究联合会倡议的一部分, 也是由特里福克斯研究所计划提供的。项目赠款 #TFF-122869 M.H. 和一个特里福克斯研究所新的研究员奖 (授予 1039) 到 M.H。

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作者声明他们没有竞争的金融利益。

考虑到染色质修饰和核定位在转录调控中的组合性质, 一种能够同时测量这些特性的方法可能会为表观遗传学的调控提供新的见解。这里介绍的 ndChIP-seq 协议是一种本地芯片-seq 协议, 用于在稀有的主单元中同时对组蛋白修饰和核密度进行审讯,9,10。ndChIP-seq 利用酶消化染色质, 当耦合到配对结束大规模并行排序和高斯混合分布模型, 允许调查组蛋白修饰在单一的核水平和由种群内异质性驱动的表剖面的反褶积。使用此协议, 我们以前报告了免疫沉淀片段大小的唯一分布, 由配对结束读取边界确定, 与 ChromHMM10,24定义的特定染色质状态相关。
ndChIP 序列库的质量取决于多种因素, 如抗体特异性和敏感性、最佳 MNase 消化条件和染色质质量。使用的抗体的特异性是关键的生产成功的 ndChIP-seq 库。一个理想的抗体显示高亲和性的表位的兴趣与小交叉反应性与其他抗原。同样重要的是选择磁性珠与最高亲和力的抗体选择。
MNase 消化是该协议中的一个关键和时间浓度敏感的反应。因此, 在处理多个样本时, 每个反应都必须在相当的时间内孵化 (参见步骤 2.2)。染色质的质量是另一个因素, 显着影响的结果 ndChIP-seq. 分裂染色质导致一个次优 MNase 消化剖面和结果在低信噪比的图书馆。本协议不推荐使用低细胞活性或降解染色质的初级样品, 如福尔马林固定石蜡 (FFPE) 组织。
在染色质提取过程中添加 PIC 可以减少不受欢迎的 (即, 随机) 染色质碎片, 并保留组蛋白尾部的完整性。因此, PIC 需要添加到裂解缓冲区和沉淀缓冲区, 才使用。在通过流式细胞仪选择细胞时, 选择可行的细胞, 并确保细胞以较低的流速排列, 以提高细胞数估计的准确性和生存能力。避免将单元格直接分类到裂解缓冲区。鞘缓冲液会稀释裂解缓冲液, 防止细胞膜的有效性 MNase。根据类型的细胞或生物体, 滴定 MNase 可能需要获得最佳的消化。
哺乳动物细胞的 ndChIP-seq 需要最小测序深度为5000万配对读 (2500万片段) 为狭窄的标记和1亿配对读 (5000万片断) 为宽广的标记和输入。高斯混合分布算法对已被测序到深度显著低于本建议的库, 将无法达到最佳性能。ndChIP-seq 将不分类促进者, 很少分离之间的加权分布值的单一和 di 核片段长度成单或 di 核主导的发起人。因此, 在随后的分析中必须删除这些启动子。可以生成生物复制, 以增加对预测分布的信心, 并确定 MNase 消化和图书馆建设中的技术变异性。
与本机芯片序列协议的以前的迭代不同, ndChIP 提供了通过利用片段大小后沉淀来整合核密度来研究染色质结构和组蛋白修饰的组合效应的方法,由 MNase 的可及性决定, 组蛋白修饰测量。ndChIP 在原发性细胞和组织中的应用, 将为表观遗传调控的综合性质提供新的见解, 并能识别由于群体内异质性而导致的后生特征。

真核细胞基因组被包装成染色质通过重复核结构, 包括两个副本的四组蛋白 (例如, H2A, H2B, H3, 和 H4) 的限制由146基对的 DNA1,2。染色质重塑复合体在基因启动子边界内控制核位置, 并通过改变 DNA 对转录因子的可及性来参与基因表达的调控, 并对 RNA 聚合酶机械3, 4。
核内组蛋白的氨基末端尾端受到各种共价键的修饰, 包括乙酰化、甲基、磷酸、化、sumo、甲, 以及特定氨基酸的羟氨酸5,6,7,8. 这些修改的位置和程度决定了染色质的状态, 影响染色质结构和控制通路的分子配合物, 允许转录活化的7。考虑到核密度和组蛋白修饰在基因转录的局部控制中起着作用, 我们开发了一种本机芯片方法, 可以同时测量核密度和组蛋白修饰9, 10。
本机芯片-seq 利用切 micrococci 核酸 (MNase) 在细胞核内的原生状态中消化完整的染色质11,12, 该属性已被杠杆映射核定位13,14,15. 核密度芯片-seq (ndChIP) 利用 MNase 对染色质的开放区域的优先访问性的特性来生成将 MNase 可访问性与组蛋白修饰10相结合的测量。ndChIP-seq 适用于在罕见的原代细胞, 组织和培养细胞的组蛋白修饰的分析。在这里, 我们提出了一个详细的协议, 使序列数据集的生成适合于先前描述的分析框架工作10 , 它集成了片段大小后沉淀, 由配对端读取边界确定, 以同时调查 MNase 的可访问性与组蛋白修饰测量。此前, 本议定书适用于1万个主要的人脐血衍生 CD34+细胞和人类胚胎干细胞揭示染色质结构和组蛋白修饰之间的独特关系在这些细胞类型中10.考虑到它能够同时测量核的可访问性和组蛋白修饰, ndChIP-seq 能够在单个核级别的单元格中揭示表特征, 并将异构签名解析为组成元素。通过 ndChIP-seq 研究异质细胞群的一个例子是对二价促进剂的调查, 其中两个 H3K4me3, 一个活跃标记, 和 H3K27me3, 一个镇压标记, 存在10。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	
	<tbody>
		<tr >
			<td >1M Tris-HCl &#8211;pH 7.5</td>
			<td >Thermo Scientific</td>
			<td >15567-027</td>
			<td ></td>
		</tr>
		<tr >
			<td >1M Tris-HCl &#8211;pH 8</td>
			<td >Thermo Scientific</td>
			<td >15568-025</td>
			<td></td>
		</tr>
		<tr >
			<td >0.5M EDTA</td>
			<td >Thermo Scientific</td>
			<td >AM9260G</td>
			<td></td>
		</tr>
		<tr >
			<td >5M NaCl</td>
			<td >Sigma</td>
			<td >1001385276</td>
			<td></td>
		</tr>
		<tr >
			<td >Triton X-100</td>
			<td >Sigma</td>
			<td >1001412354</td>
			<td></td>
		</tr>
		<tr >
			<td >Sodium-Deoxycholate</td>
			<td >Sigma</td>
			<td >1001437582</td>
			<td></td>
		</tr>
		<tr >
			<td >SDS</td>
			<td >Thermo Scientific</td>
			<td >15525-017</td>
			<td></td>
		</tr>
		<tr >
			<td >Sodium-Bicarbonate</td>
			<td >Fisher Scientific</td>
			<td >S233-500</td>
			<td></td>
		</tr>
		<tr >
			<td >100% EtOH</td>
			<td >NA</td>
			<td >NA</td>
			<td></td>
		</tr>
		<tr >
			<td >V-bottom 96 well plate (AB 1400)</td>
			<td >Thermo Scientific</td>
			<td >AB-1400-L</td>
			<td></td>
		</tr>
		<tr >
			<td >Gilson P2 pipetman</td>
			<td >Mandel</td>
			<td >F144801</td>
			<td></td>
		</tr>
		<tr >
			<td >Gilson P10 pipetman</td>
			<td >Mandel</td>
			<td >F144802</td>
			<td></td>
		</tr>
		<tr >
			<td >Gilson P20 pipetman</td>
			<td >Mandel</td>
			<td >F123600</td>
			<td></td>
		</tr>
		<tr >
			<td >Gilson P100 pipetman</td>
			<td >Mandel</td>
			<td >F123615</td>
			<td></td>
		</tr>
		<tr >
			<td >Gilson P200 pipetman</td>
			<td >Mandel</td>
			<td >F123601</td>
			<td></td>
		</tr>
		<tr >
			<td >Gilson P1000 pipetman</td>
			<td >Mandel</td>
			<td >F123603</td>
			<td></td>
		</tr>
		<tr >
			<td >Micrococcal Nuclease&#160;</td>
			<td >NEB</td>
			<td >M0247S</td>
			<td></td>
		</tr>
		<tr >
			<td >Thermo Mixer C (Heating block mixer)</td>
			<td >Eppendorf</td>
			<td >5382000023</td>
			<td></td>
		</tr>
		<tr >
			<td >Multi 12-channel Pippet P20</td>
			<td >Rainin</td>
			<td >17013803</td>
			<td></td>
		</tr>
		<tr >
			<td >Multi 12-channel Pippet P200</td>
			<td >Rainin</td>
			<td >17013805</td>
			<td></td>
		</tr>
		<tr >
			<td >1.5 ml LoBind tube</td>
			<td >Eppendorf</td>
			<td >22431021</td>
			<td></td>
		</tr>
		<tr >
			<td >0.5 ml LoBind tube</td>
			<td >Eppendorf</td>
			<td >22431005</td>
			<td></td>
		</tr>
		<tr >
			<td >Plastic Plate Cover</td>
			<td >Edge Bio</td>
			<td >48461</td>
			<td></td>
		</tr>
		<tr >
			<td >PCR cover</td>
			<td >Bio Rad</td>
			<td >MSD-1001</td>
			<td></td>
		</tr>
		<tr >
			<td >Aluminum Plate Cover</td>
			<td >Bio Rad</td>
			<td >MSF-1001</td>
			<td></td>
		</tr>
		<tr >
			<td >Elution buffer (EB buffer)</td>
			<td >Qiagen</td>
			<td >19086</td>
			<td></td>
		</tr>
		<tr >
			<td >1M DTT</td>
			<td >Sigma</td>
			<td >646563</td>
			<td></td>
		</tr>
		<tr >
			<td >Eppendorf 5810R centrifuge&#160;</td>
			<td >Eppendorf</td>
			<td >22625004</td>
			<td></td>
		</tr>
		<tr >
			<td >Ultrapure water</td>
			<td >Thermo Scientific</td>
			<td >10977-015</td>
			<td></td>
		</tr>
		<tr >
			<td >Protein G dynabeads</td>
			<td >Thermo Scientific</td>
			<td >10001D</td>
			<td></td>
		</tr>
		<tr >
			<td >Protein A dynabeads</td>
			<td >Thermo Scientific</td>
			<td >10001D</td>
			<td></td>
		</tr>
		<tr >
			<td >Protease inhibitor Cocktail</td>
			<td >Calbiochem</td>
			<td >539134</td>
			<td></td>
		</tr>
		<tr >
			<td >Rotating platform</td>
			<td >Mandel</td>
			<td >1b109-12052010</td>
			<td></td>
		</tr>
		<tr >
			<td >Plate magnet</td>
			<td >Alpaqua</td>
			<td >2523</td>
			<td></td>
		</tr>
		<tr >
			<td >Domed 12-cap strip</td>
			<td >Bio Rad</td>
			<td >TCS1201</td>
			<td></td>
		</tr>
		<tr >
			<td >Buffer G2</td>
			<td >Qiagen</td>
			<td >1014636</td>
			<td></td>
		</tr>
		<tr >
			<td >Protease</td>
			<td >Qiagen</td>
			<td >19155</td>
			<td></td>
		</tr>
		<tr >
			<td>Tube Magnet (DynaMag-2)</td>
			<td >Thermo Scientific</td>
			<td >12321D</td>
			<td></td>
		</tr>
		<tr >
		<td>Tube Magnet (DynaMag-2)</td>
			<td >LabCore</td>
			<td >730-006</td>
			<td></td>
		</tr>
		<tr >
			<td >V shape Plastic reservoir</td>
			<td >Mandel</td>
			<td >S0100A</td>
			<td></td>
		</tr>
		<tr >
			<td >Vortex</td>
			<td >Mandel</td>
			<td >C1801</td>
			<td></td>
		</tr>
		<tr >
			<td >Mini Fuge</td>
			<td >Mettler Toledo</td>
			<td >XS2035</td>
			<td></td>
		</tr>
		<tr >
			<td >Analytical scale</td>
			<td >Mandel</td>
			<td >LB109-12052010</td>
			<td></td>
		</tr>
		<tr >
			<td >Quick Ligation Reaction Buffer, 5X</td>
			<td >NEB</td>
			<td>B6058S</td>
			<td></td>
		</tr>
		<tr >
			<td >DNA Polymerase I, Large (Klenow) Fragment</td>
			<td >NEB</td>
			<td>M0210S</td>
			<td></td>
		</tr>
		<tr >
			<td >Klenow Fragment (3&#39;-5&#39; exo)</td>
			<td >NEB</td>
			<td>M0212S</td>
			<td></td>
		</tr>
		<tr >
			<td >T4 DNA Polymerase</td>
			<td >NEB</td>
			<td>M0203S</td>
			<td></td>
		</tr>
		<tr >
			<td >T4 Polynucleotide Kinase</td>
			<td >NEB</td>
			<td>M0201S</td>
			<td></td>
		</tr>
		<tr >
			<td >Deoxynucleotide Solution mix, 10mM</td>
			<td >NEB</td>
			<td>N0447S</td>
			<td></td>
		</tr>
		<tr >
			<td >dATP Solution 10mM</td>
			<td >NEB</td>
			<td>N0440S</td>
			<td></td>
		</tr>
		<tr >
			<td >Quick T4 DNA Ligase</td>
			<td >NEB</td>
			<td>M0202T</td>
			<td></td>
		</tr>
		<tr >
			<td >Adenosine 5&#39;-Triphosphate (ATP), 25mM</td>
			<td >NEB</td>
			<td>P0756S</td>
			<td></td>
		</tr>
		<tr >
			<td >DNA Polymerase</td>
			<td >Thermo Scientific</td>
			<td>F549L</td>
			<td></td>
		</tr>
		<tr >
			<td >NEBuffer 2</td>
			<td >NEB</td>
			<td>B7002S</td>
			<td></td>
		</tr>
		<tr >
			<td >Hank&#39;s buffered salt solution</td>
			<td >Thermo Scientific</td>
			<td>14025076</td>
			<td></td>
		</tr>
		<tr >
			<td >Fetal bovine serum&#160;</td>
			<td >Thermo Scientific</td>
			<td>A3160702</td>
			<td></td>
		</tr>
		<tr >
			<td >phosphate buffer saline&#160;</td>
			<td >Thermo Scientific</td>
			<td>10010023</td>
			<td></td>
		</tr>
		<tr >
			<td >H3K4me3</td>
			<td >Cell Signaling</td>
			<td >9751S</td>
			<td></td>
		</tr>
		<tr >
			<td >H3K4me1</td>
			<td >Diagenode</td>
			<td >C15410037</td>
			<td></td>
		</tr>
		<tr >
			<td >H3K27me3</td>
			<td >Diagenode</td>
			<td >pAb-069-050</td>
			<td></td>
		</tr>
		<tr >
			<td >H3K36me3</td>
			<td >Abcam</td>
			<td >ab9050</td>
			<td></td>
		</tr>
		<tr >
			<td >H3K9me3</td>
			<td >Diagenode</td>
			<td >C15410056</td>
			<td></td>
		</tr>
		<tr >
			<td >SeraMag&#160; super-paramagnetic beads</td>
			<td ></td>
			<td ></td>
			<td></td>
		</tr>
	</tbody>
</table>

generation of native chromatin immunoprecipitation sequencing libraries for nucleosome density analysis

我们提出了一个改进的本地染色质沉淀测序 (芯片-seq) 实验协议兼容的高斯混合分布的分析方法 (核密度芯片序列; ndChIP-seq), 使生成的micrococcal 核酸 (MNase) 可及性与组蛋白修饰的联合测量。核位置和局部密度, 以及对其组蛋白亚基的后修饰, 协同调节局部转录状态。组合测量的核可达性与组蛋白修饰产生的 ndChIP-seq 允许同时审讯这些功能。ndChIP-seq 方法适用于基于交联的芯片-seq 协议的小数目的原电池。在一起, ndChIP-seq 使测量组蛋白修饰结合局部核密度, 以获得新的洞察力的共享机制, 调节 RNA 转录在稀有的原细胞群体。

Watch this Scientific Journal Video about Generation of Native Chromatin Immunoprecipitation Sequencing Libraries for Nucleosome Density Analysis at JoVE.com

Generation of Native Chromatin Immunoprecipitation Sequencing Libraries for Nucleosome Density Analysis

核密度分析的天然染色质沉淀测序文库的生成

我们提出了一个改良的本地染色质沉淀测序 (芯片-seq) 的方法, 以生成序列数据集适合核密度芯片-seq 分析框架集成 micrococcal 核酸 (MNase) 可及性组蛋白修饰测量。

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

generation-native-chromatin-immunoprecipitation-sequencing-libraries

Research

JoVE Journal

Genetics

22.0K 次观看.  University of British Columbia. 我们提出了一个改良的本地染色质沉淀测序 (芯片-seq) 的方法, 以生成序列数据集适合核密度芯片-seq 分析框架集成 micrococcal 核酸 (MNase) 可及性组蛋白修饰测量。

视频: Generation of Native Chromatin Immunoprecipitation Sequencing Libraries for Nucleosome Density Analysis

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.

序贯盐萃取法分析染色质修饰配合物的体染色质结合特性

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

科研

遗传学

Optimization and Comparative Analysis of Plant Organellar DNA Enrichment Methods Suitable for Next-generation Sequencing

Plant organellar genomes contain large, repetitive elements that may undergo pairing or recombination to form complex structures and/or sub-genomic fragments. Organellar genomes also exist in admixtures within a given cell or tissue type (heteroplasmy), and an abundance of subtypes may change throughout development or when under stress (sub-stoichiometric shifting). Next-generation sequencing (NGS) technologies are required to obtain deeper understanding of organellar genome structure and function. Traditional sequencing studies use several methods to obtain organellar DNA: (1) If a large amount of starting tissue is used, it is homogenized and subjected to differential centrifugation and/or gradient purification. (2) If a smaller amount of tissue is used (i.e., if seeds, material, or space is limited), the same process is performed as in (1), followed by whole-genome amplification to obtain sufficient DNA. (3) Bioinformatics analysis can be used to sequence the total genomic DNA and to parse out organellar reads. All these methods have inherent challenges and tradeoffs. In (1), it may be difficult to obtain such a large amount of starting tissue; in (2), whole-genome amplification could introduce a sequencing bias; and in (3), homology between nuclear and organellar genomes could interfere with assembly and analysis. In plants with large nuclear genomes, it is advantageous to enrich for organellar DNA to reduce sequencing costs and sequence complexity for bioinformatics analyses. Here, we compare a traditional differential centrifugation method with a fourth method, an adapted CpG-methyl pulldown approach, to separate the total genomic DNA into nuclear and organellar fractions. Both methods yield sufficient DNA for NGS, DNA that is highly enriched for organellar sequences, albeit at different ratios in mitochondria and chloroplasts. We present the optimization of these methods for wheat leaf tissue and discuss major advantages and disadvantages of each approach in the context of sample input, protocol ease, and downstream application.

The comparison and optimization of two plant organellar DNA enrichment methods are presented: traditional differential centrifugation and fractionation of the total gDNA based on methylation status. We assess the resulting DNA quantity and quality, demonstrate performance in short-read next-generation sequencing, and discuss the potential for use in long-read single-molecule sequencing.

适用于下一代测序的植物细菌DNA富集方法的优化与比较分析

Plant organellar genomes contain large, repetitive elements that may undergo pairing or recombination to form complex structures and/or sub-genomic ...

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.

使用染色质免疫沉淀分析c-KIT配体启动子

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.

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 ...

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.

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.

低丰度胚胎标本的染色质沉淀 (芯片) 协议

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

Generation of Genome-wide Chromatin Conformation Capture Libraries from Tightly Staged Early Drosophila Embryos

Investigating the three-dimensional architecture of chromatin offers invaluable insight into the mechanisms of gene regulation. Here, we describe a protocol for performing the chromatin conformation capture technique in situ Hi-C on staged Drosophila melanogaster embryo populations. The result is a sequencing library that allows the mapping of all chromatin interactions that occur in the nucleus in a single experiment. Embryo sorting is done manually using a fluorescent stereo microscope and a transgenic fly line containing a nuclear marker. Using this technique, embryo populations from each nuclear division cycle, and with defined cell cycle status, can be obtained with very high purity. The protocol may also be adapted to sort older embryos beyond gastrulation. Sorted embryos are used as inputs for in situ Hi-C. All experiments, including sequencing library preparation, can be completed in five days. The protocol has low input requirements and works reliably using 20 blastoderm stage embryos as input material. The end result is a sequencing library for next generation sequencing. After sequencing, the data can be processed into genome-wide chromatin interaction maps that can be analyzed using a wide range of available tools to gain information about topologically associating domain (TAD) structure, chromatin loops, and chromatin compartments during Drosophila development.

Generation of Genome-wide Chromatin Conformation Capture Libraries from Tightly Staged Early Drosophila Embryos

This work describes a protocol for the generation of high resolution in situ Hi-C libraries from tightly staged pre-gastrulation Drosophila melanogaster embryos.

大范围早期果蝇胚胎的全基因组染色质构象捕获库的生成

Investigating the three-dimensional architecture of chromatin offers invaluable insight into the mechanisms of gene regulation. Here, we describe a ...

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.

从酿酒酵母中组蛋白修饰的染色质沉淀 (芯片)

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.

小鼠棕色脂肪组织的染色质免疫沉淀

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.

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 ...

Identification of Footprints of RNA:Protein Complexes via RNA Immunoprecipitation in Tandem Followed by Sequencing (RIPiT-Seq)

RNA immunoprecipitation in tandem (RIPiT) is a method for enriching RNA footprints of a pair of proteins within an RNA:protein (RNP) complex. RIPiT employs two purification steps. First, immunoprecipitation of a tagged RNP subunit is followed by mild RNase digestion and subsequent non-denaturing affinity elution. A second immunoprecipitation of another RNP subunit allows for enrichment of a defined complex. Following a denaturing elution of RNAs and proteins, the RNA footprints are converted into high-throughput DNA sequencing libraries. Unlike the more popular ultraviolet (UV) crosslinking followed by immunoprecipitation (CLIP) approach to enrich RBP binding sites, RIPiT is UV-crosslinking independent. Hence RIPiT can be applied to numerous proteins present in the RNA interactome and beyond that are essential to RNA regulation but do not directly contact the RNA or UV-crosslink poorly to RNA. The two purification steps in RIPiT provide an additional advantage of identifying binding sites where a protein of interest acts in partnership with another cofactor. The double purification strategy also serves to enhance signal by limiting background. Here, we provide a step-wise procedure to perform RIPiT and to generate high-throughput sequencing libraries from isolated RNA footprints. We also outline RIPiT&#39;s advantages and applications and discuss some of its limitations.

Identification of Footprints of RNA:Protein Complexes via RNA Immunoprecipitation in Tandem Followed by Sequencing RIPiT-Seq

Here, we present a protocol to enrich endogenous RNA binding sites or &#34;footprints&#34;&#160;of RNA:protein (RNP) complexes from mammalian cells. This approach involves two immunoprecipitations of RNP subunits and is therefore dubbed RNA immunoprecipitation in tandem (RIPiT).

RNA足迹的识别:通过RNA免疫沉淀在串联中的蛋白质复合物,然后测序(RIPiT-Seq)

RNA immunoprecipitation in tandem (RIPiT) is a method for enriching RNA footprints of a pair of proteins within an RNA:protein (RNP) complex. RIPiT ...