The authors would like to acknowledge The Plant Cell for allowing the use of some data published in this journal to elaborate the representative results described here in Figure 4. This work was supported by the EU 7FP Marie Curie-Initial Training Network EpiTRAITS (Grant Agreement 316965), and by the Spanish Ministerio de Econom&#236;a y Competitividad (grants BIO2010-15589 and BIO2013-43098-R).

1.交联的植物材料（1小时） <ol><li>生长在实验中使用的Arabidopsis品系（野生型 - WT - 与突变体，和/或线表达自己感兴趣的蛋白质的相对线表达该标记的标记版本不融合的任何蛋白质）12-18天上大培养皿（150毫米）与MS琼脂培养基（1L:1个的Murashige＆Skoog盐，10g的蔗糖，0.5g的MES，pH值5.7（KOH），1％琼脂）。另外，生长在含有3盆植物:1混合土和蛭石。 注意！甲醛是通过吸入，皮肤接触及吞食，并应在化学罩穿上适当的个人防护装备进行处理。步骤1.2 - 1.6应在通风橱下进行。 </li><li>使在50ml试管用实验室燃烧器加热的针的盖小的孔。加入40毫升的1×PBS缓冲液和1.08甲醛毫升至1％的终浓度（股票37％s的olution）。收集1.5克植物材料在这些50ml试管。请交联过程中冰上管。 </li><li>关闭50ml试管与盖。将管在干燥器和施加真空。真空渗入组织10分钟，然后小心地释放真空，以防止搅动起来的溶液。混合样本。重复两次。浸润后，观察植物材料，并确认它变得稍微半透明的，并趋向于下沉到管（图2） 的底部。 </li><li>添加2.5毫升2M的甘氨酸以达到0.125 M的最终浓度应用真空5分钟。甘氨酸作为甲醛交联的竞争性抑制剂。 </li><li>通过反转闭合50ml管中，在该盖的孔丢弃PBS甲醛甘氨酸溶液。 </li><li>与如在步骤1.5中所述的水弃去洗涤液冲洗小植株两次用1×PBS和一次。干他们在纸巾上并冷冻在液态nitrogeñ。 注:冷冻组织可保持在-80℃为周。 </li></ol> 2.制备的抗体的（1天） 注:对于免疫沉淀，利用经由蛋白质G或蛋白质与抗体重链的恒定结构域的高亲和性的连接物结合有抗体的磁珠被推荐。的DNA-蛋白复合物可以非特异性地连接到所述珠 - 抗体偶联物的表面上。出于这个原因，有必要进行控制，而不特异性抗体来定量非特异性背景结合。 <ol><li>对于每一个免疫沉淀，制备15微升磁珠在1.5ml微量离心管中。的小珠的量取决于用于免疫沉淀和也对抗体的染色质的量。 </li><li>洗，加入1 ml的染色质免疫沉淀（ChIP）稀释缓冲液至珠，通过旋转混合，然后将1.5 ml微量涂在一个磁性机架。等待约1分钟，以让所述珠附着到磁体。与1.5 ml微量离心管仍然在机架上，通过移液除去上清液。重复两次。 注:对于每个植物系，需要两个免疫组:1与珠子和抗体（抗体）和第二无抗体（无抗体）控制与仅磁珠。 </li><li>重悬在200微升的ChIP稀释缓冲液珠。添加所需的特异性Ab的量为每个植物系中制备的两个管中的一个（确切稀释不同于每个Ab和具有由实验优化，或在商业抗体的情况下，按照制造商的说明）。使用该样品进行免疫沉淀。添加非特异性IgG的相同量的其他管，其将被用作阴性对照。 </li><li>孵育O / N上的旋转轮，在4​​℃下，让该抗体附着到珠子上。 </li></ol> 3.染色质萃取（4小时） </p&gt; <ol><li>使用研钵和杵直到粉末变得均匀和浅绿色研磨彻底冷冻植物材料在液氮中。粉末转移到一个新50ml管中。 </li><li>对于步骤3.2 - 3.6，工作通风柜下。加入30毫升提取缓冲液1（EXB 1），拌匀浸泡组织粉末。从在此步骤中，保持所述样品在4℃下在任何时候。冷冻组织和液氮剩菜将导致缓冲器冻结。确保反相管4-5次，每次2分钟完全解冻冷冻组织。 </li><li>通过在4℃下使其通过一过滤组织具有22-25微米孔径到一个新的50ml管中，并离心它在1000×g离心20分钟清除浆料。 注:在这一步骤中，细胞核，所有的细胞器将沉淀。 EXB 1含有足够的蔗糖，以提供高密度，防止细胞器结构的破坏。 </li><li>轻轻倾析去除上清。在这站GE，观察约2毫升生球。 </li><li>重悬在5ml EXB的粒料2.再悬浮颗粒将难以在这一点上。离心机在1000×g离心在4℃下10分钟。 注:EXB 2中含有1％的Triton X-100不由一阵叶绿体开并取下叶绿素。 </li><li>重悬在300微升提取液3（EXB 3）的颗粒。 </li><li>在一个干净的离心管中，加入600微升预算外3.取悬浮颗粒从步骤3.6和仔细的清洁预算外3的顶部层吧。 </li><li>自旋为1小时，在16000×g离心在4℃下。 注:此步骤有助于除去从样品的洗涤剂。 </li><li>通过用移液管抽吸除去上清液。通过缓慢上下抽吸，以避免形成气泡，这可能会影响声处理效率重悬在300微升超声缓冲液的核沉淀。认真吸取所有的悬挂出来，转移到一个干净的1.5 ml离心管。 注:此缓冲液含有SDS，以裂解细胞核和释放染色质。 </li><li>超声处理该悬浮液以裂解细胞核和随机剪切染色质成小碎片。使用该渲染染色质富集200-800碱基对之间的片段（20-30个周期的设置30秒开/ 30秒关，在4℃下可利用的材料/试剂的表中所描述的超声处理装置）超声处理的条件。检查超声处理将所得到的DNA片段的电泳分离的效率在琼脂糖凝胶上13，加载2微升超声染色质（图3）。 小心！确保期间中的情况下超声装置不包含在一个隔音柜内超声处理步骤到穿耳朵保护设备。 关键的一步！染色质碎片在很大程度上取决于超声设备。超声处理条件应进行调整，以实现富集的合适的DNA尺寸。看到图3为如何优化染色质片段化的一个例子。 </li><li>旋溶液一次以12,000rpm离心10分钟，在4℃。上清液通过移液枪转移到一个干净的1.5 ml离心管。弃沉淀。取上清的1/10到一个新的1.5 ml离心管，将其标记为输入并冷冻在-20℃。 </li><li>稀释10倍的染色质与沉淀稀释缓冲液稀释的SDS达到0.1％的最终浓度。 注意:样品可以冷冻并储存在-20℃下几个星期。 </li></ol> 4.免疫沉淀利益的蛋白质和DNA的救援（1天，3小时） <ol><li>从步骤用1ml的ChIP稀释缓冲液洗涂覆有抗体的珠子的2.4三倍如步骤2.2中所述，以除去过量的抗体。重悬在200微升的ChIP稀释缓冲液。加入50微升孤立的染色质。孵育O / N旋转轮上，在4℃。 注:检查concentrati在微量紫外可见分光光度计的染色质。 50微升孤立染色质应包含超过10个的DNA微克。 </li><li>对于在4℃的步骤4.2-4.5工作。如在步骤2.2中描述的1ml低盐洗涤缓冲液洗两次的珠。 </li><li> 1毫升高盐洗涤缓冲液洗一次的珠子。 </li><li>在1ml的LiCl洗涤缓冲液洗一次珠。 </li><li>在1ml TE缓冲液洗两次的珠。最后一次洗涤后，请务必通过抽吸完全删除TE缓冲留在管吸管。 </li><li>取出输入样本（步骤3.9）。转印5微升输入到一个新的1.5 ml离心管，并继续作为与芯片的样品。反向加入200微升5％的螯合离子交换树脂的交联，并孵育10分钟，在95℃下振荡，每2-3分钟。降速在16000×g离心30秒，小心地通过吸液将上清液转移到一个新的离心管中。 注意:当TRA用于交联的逆转ditional方法涉及的O / N培养用NaCl，与螯合离子树脂在95℃下温育允许有效解交联和DNA在10分钟洗脱，因此使得协议之一天缩短。 </li><li>加入2微升蛋白酶K（10毫克/毫升），并在37℃下30分钟以消化蛋白质并释放DNA。 </li><li>停止反应，在95℃下孵育10分钟。 </li><li>快速旋转，在16000×g离心30秒，并通过移液转移上清至新管。 </li><li>清洁用标准的DNA片段纯化试剂盒的DNA分离出来。 注:根据制造商的说明进行操作。 </li><li>从试剂盒中的DNA结合柱转移到新的1.5ml微量管中。通过加入20微升DNA酶的水，以塔的中心，并在16000×g离心纺丝60秒洗脱纯化的DNA。停止点:样品可以贮存于-80℃下几个星期。 </li></OL&gt; 5.测量结合位点的免疫沉淀DNA通过qPCR的丰度（4小时） 注:脱氧核糖核酸从沉淀的染色质中分离已被分析，以确定哪些DNA片段已沉淀-编从总染色质，由于它结合到感兴趣的蛋白质。 <ol><li>设计的引物用于以60℃的熔融温度（Tm）为30％-80％的GC含量感兴趣的基因组区域。染色质通过超声处理片段化，扩增序列的长度不应该比150-200个核苷酸（表1）长。 注:引物设计的一个有用的工具是底漆3程序（http://bioinfo.ut.ee/primer3-0.4.0/）。对于引物设计的附加 ​​准则在以前的报告中8，14，15。 </li><li>使用BLAST程序，以确保引物是特定的（特别是启动子可以共享相似TF结合序列）和测试引物效率使用设克1点10稀释在输入脱氧核糖核酸（步骤4.9）的水中。基因组的特定区域将被净化比别人做得更好。因此，重要的是设计PCR引物，并检查它们的稀释输入的DNA。 </li><li>稀释纯化的DNA以1:10的水和吸管在PCR管为每个反应取5μl稀释的DNA。 注的稀释:仅在需要的量，因为DNA可以连接到1.5 ml微量离心管的壁。多个解冻冷冻循环增加附着的DNA分子的数量。对于每个引物对，扩增在输入，抗体芯片和无抗体的ChIP已经被分析。 </li><li>要完成PCR混合物，SYBR绿PCR主混合物添加到1倍的终浓度，及0.5每种引物μM。填充至20微升用DNase的水。 </li><li>执行定量PCR反应后的的SYBR Green PCR主混合物制造商的说明。 </li></ol> 6.数据分析注:其中前isting分析的ChIP-数据的方式，两个是最常用的。的其中第一个是在倍富集方法，也命名为"相对富集"，"信号超过背景"或"相对于无抗体对照&#39;。第二种方法被命名为"％输入的"。 <ol><li>通过倍富集法数据分析。 <ol><li>创建与已定量PCR反应后获得的样品名称和原始Ct值的电子表格。 </li><li>对于每个样品，从它的原始Ct值减去用于相应无抗体对照获得的原始Ct值。注:本数学运算后，对于无抗体样品Ct值将等于0。 </li><li>通过求幂运算计算倍富集与基座2和指数（功率）等于在步骤6.1.2（表2）中获得的负的余数。 倍浓缩= 2 -数（Ct（样品） -的Ct（无抗体）） 注:在此实现方法具D中的ChIP-ED试样中的特定DNA片段的丰度与该片段中无抗体对照的丰度进行比较。该方法的前提是，背景信号的电平是可重复的不同的引物组，样品，并重复实验之间。然而，这种&#39;noise&#39;信号电平做引物组，样品和实验之间变化。 </li></ol></li><li>由％输入法的数据分析。 <ol><li>创建与样品名称和qPCR反应后已获得他们的原始Ct值的电子表格。 </li><li>通过从总提取染色质的被取作输入的分数中减去对数底数2的值调整原始Ct值对输入样本。 注:在本协议中的减值等于3.32，占总染色质的10％被作为一个输入在这个协议。日志2（10）等于3.32。 </li><li>通过乘以100求幂运算的用b值计算％输入的酶2和指数（功率）等于从样品（见表3）的原始Ct值中减去调整后的输入值的剩余部分。 ％输入= 100 * 2 （调整后的输入-的Ct（样品）） 注意:对于这个过程，以总孤立染色质（输入取样）特异性DNA丰度的片编样品之间的关系来计算。芯片数据分析的进一步细节，可以在哈林等人 8中找到。 </li></ol></li></ol>

<ol>
	<li>Andres, F., Coupland, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+genetic+basis+of+flowering+responses+to+seasonal+cues.">The genetic basis of flowering responses to seasonal cues.</a> Nat Rev Genet. 13 (9), 627-639 (2012).</li><li>Capovilla, G., Schmid, M., Pose, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+flowering+by+ambient+temperature.">Control of flowering by ambient temperature.</a> J Exp Bot. 66 (1), 59-69 (2015).</li><li>Jarillo, J. A., Pi&#241;eiro, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Timing+is+everything+in+plant+development.+The+central+role+of+floral+repressors.">Timing is everything in plant development. The central role of floral repressors.</a> Plant Science. 181 (4), 364-378 (2011).</li><li>Pajoro, 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=The+(r)evolution+of+gene+regulatory+networks+controlling+Arabidopsis+plant+reproduction:+a+two-decade+history.">The (r)evolution of gene regulatory networks controlling Arabidopsis plant reproduction: a two-decade history.</a> J Exp Bot. 65 (17), 4731-4745 (2014).</li><li>He, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatin+regulation+of+flowering.">Chromatin regulation of flowering.</a> Trends Plant Sci. 17 (9), 556-562 (2012).</li><li>Jarillo, J. A., Pineiro, M., Cubas, P., Martinez-Zapater, J. 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+remodeling+in+plant+development.">Chromatin remodeling in plant development.</a> International Journal of Developmental Biology. 53 (8-10), 1581-1596 (2009).</li><li>Saleh, A., Alvarez-Venegas, R., Avramova, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+efficient+chromatin+immunoprecipitation+(ChIP)+protocol+for+studying+histone+modifications+in+Arabidopsis+plants.">An efficient chromatin immunoprecipitation (ChIP) protocol for studying histone modifications in Arabidopsis plants.</a> Nat Protoc. 3 (6), 1018-1025 (2008).</li><li>Haring, M., 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=Chromatin+immunoprecipitation:+optimization,+quantitative+analysis+and+data+normalization.">Chromatin immunoprecipitation: optimization, quantitative analysis and data normalization.</a> Plant Methods. 3, 11 (2007).</li><li>Kaufmann, 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=Chromatin+immunoprecipitation+(ChIP)+of+plant+transcription+factors+followed+by+sequencing+(ChIP-SEQ)+or+hybridization+to+whole+genome+arrays+(ChIP-CHIP).">Chromatin immunoprecipitation (ChIP) of plant transcription factors followed by sequencing (ChIP-SEQ) or hybridization to whole genome arrays (ChIP-CHIP).</a> Nat Protoc. 5 (3), 457-472 (2010).</li><li>Gomez-Mena, 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=early+bolting+in+short+days:+An+Arabidopsis+mutation+that+causes+early+flowering+and+partially+suppresses+the+floral+phenotype+of+leafy.">early bolting in short days: An Arabidopsis mutation that causes early flowering and partially suppresses the floral phenotype of leafy.</a> Plant Cell. 13 (5), 1011-1024 (2001).</li><li>Pi&#241;eiro, M., Gomez-Mena, C., Schaffer, R., Martinez-Zapater, J. M., Coupland, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EARLY+BOLTING+IN+SHORT+DAYS+is+related+to+chromatin+remodeling+factors+and+regulates+flowering+in+Arabidopsis+by+repressing+FT.">EARLY BOLTING IN SHORT DAYS is related to chromatin remodeling factors and regulates flowering in Arabidopsis by repressing FT.</a> Plant Cell. 15 (7), 1552-1562 (2003).</li><li>Lopez-Gonzalez, 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=Chromatin-dependent+repression+of+the+Arabidopsis+floral+integrator+genes+involves+plant+specific+PHD-containing+proteins.">Chromatin-dependent repression of the Arabidopsis floral integrator genes involves plant specific PHD-containing proteins.</a> Plant Cell. 26 (10), 3922-3938 (2014).</li><li>Sambrook, J., Fritsch, E. F., Maniatis, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Molecular Cloning: A Laboratory Manual. , (1989).</li><li>Lorenz, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymerase+Chain+Reaction:+Basic+Protocol+Plus+Troubleshooting+and+Optimization+Strategies.">Polymerase Chain Reaction: Basic Protocol Plus Troubleshooting and Optimization Strategies.</a> J. Vis. Exp. , e3998 (2012).</li><li>Wong, M. L., Medrano, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+PCR+for+mRNA+quantitation.">Real-time PCR for mRNA quantitation.</a> Biotechniques. 39 (1), 75-85 (2005).</li><li>Dedon, P. C., Soults, J. A., Allis, C. D., Gorovsky, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simplified+formaldehyde+fixation+and+immunoprecipitation+technique+for+studying+protein-DNA+interactions.">A simplified formaldehyde fixation and immunoprecipitation technique for studying protein-DNA interactions.</a> Anal Biochem. 197 (1), 83-90 (1991).</li><li>Yu, C. W., 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+DEACETYLASE6+interacts+with+FLOWERING+LOCUS+D+and+regulates+flowering+in+Arabidopsis.">HISTONE DEACETYLASE6 interacts with FLOWERING LOCUS D and regulates flowering in Arabidopsis.</a> Plant Physiology. 156 (1), 173-184 (2011).</li><li>Zhou, 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=Genome-wide+profiling+of+histone+H3+lysine+9+acetylation+and+dimethylation+in+Arabidopsis+reveals+correlation+between+multiple+histone+marks+and+gene+expression.">Genome-wide profiling of histone H3 lysine 9 acetylation and dimethylation in Arabidopsis reveals correlation between multiple histone marks and gene expression.</a> Plant Mol Biol. 72 (6), 585-595 (2010).</li><li>Lafos, M., 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=Dynamic+regulation+of+H3K27+trimethylation+during+Arabidopsis+differentiation.">Dynamic regulation of H3K27 trimethylation during Arabidopsis differentiation.</a> PLoS Genet. 7 (4), e1002040 (2011).</li><li>Barcala, M., Fenoll, C., Escobar, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+microdissection+of+cells+and+isolation+of+high-quality+RNA+after+cryosectioning.">Laser microdissection of cells and isolation of high-quality RNA after cryosectioning.</a> Methods Mol Biol. 883, 87-95 (2012).</li><li>Carter, A. D., Bonyadi, R., Gifford, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+fluorescence-activated+cell+sorting+in+studying+plant+development+and+environmental+responses.">The use of fluorescence-activated cell sorting in studying plant development and environmental responses.</a> Int J Dev Biol. 57 (6-8), 545-552 (2013).</li><li>Deal, R. B., Henikoff, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+INTACT+method+for+cell+type-specific+gene+expression+and+chromatin+profiling+in+Arabidopsis+thaliana.">The INTACT method for cell type-specific gene expression and chromatin profiling in Arabidopsis thaliana.</a> Nat Protoc. 6 (1), 56-68 (2011).</li><li>Zeng, P. Y., Vakoc, C. R., Chen, Z. C., Blobel, G. A., Berger, S. L. <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+dual+cross-linking+for+identification+of+indirect+DNA-associated+proteins+by+chromatin+immunoprecipitation.">In vivo dual cross-linking for identification of indirect DNA-associated proteins by chromatin immunoprecipitation.</a> Biotechniques. 41 (6), 694-698 (2006).</li><li>Das, P. M., Ramachandran, K., vanWert, J., Singal, R. <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+assay.">Chromatin immunoprecipitation assay.</a> Biotechniques. 37 (6), 961-969 (2004).</li><li>Kaufmann, 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=Target+genes+of+the+MADS+transcription+factor+SEPALLATA3:+integration+of+developmental+and+hormonal+pathways+in+the+Arabidopsis+flower.">Target genes of the MADS transcription factor SEPALLATA3: integration of developmental and hormonal pathways in the Arabidopsis flower.</a> PLoS Biol. 7 (4), e1000090 (2009).</li></ol>

The authors declare that they have no competing financial interests.

此处所描述的沉淀协议是一个可再现的和强大的技术来分析蛋白质和特定的DNA序列之间的相互作用在体内在拟南芥植物。一个成功的鉴定结合位点的目的蛋白质需要适当的选择植物器官或发育阶段，其中相关的相互作用实际上是正在发生的。此外，重要的是，获得的植物材料的适当的固定和染色质的通过超声处理的最佳剪切。是对于所选择的蛋白质/标签的有效免疫沉淀的高度特异性抗体也...

近年来广泛的遗传，分子和基因组工具被开发在模型物种拟南芥。该技术促进了极大的进展，了解如何植物生长发育的调节。在使用拟南芥为模式研究的发展过程中，开花时间的基因控制已经被广泛分析。这些研究表明，植物开花响应于内源性线索非常精确的时间调制如激素和植物的年龄，并且还认为则同步开花时间随着季节1的自然循环环境信号诸如光周期和温度， 2。拟南芥突变体的分离和鉴定与改建开花的时候已经决定在公布的基因，调节开花时间响应内源性因素和环境因素的复杂网络。这些遗传电路集成在充当开花交换机的几个主基因水平和花芽分化的确切时间取决于促进开花，压制这项工作的花卉积分基因1,3上游活动的平衡。 确定了其在开花开始的控制作用的基因的功能特性，由最近使用基因组学方法的帮助下，已揭示转录调控中的开花时间的调制的中心作用。事实上，许多的开花编码转录的主控基因因子4。此外，一些染色质重塑蛋白复合物影响开花的主基因的表达。许多拟南芥突变体中分离得到的改变的开花时间的横空出世，携带突变基因编码的各种染色质修饰的。不同的染色质remodelers的引入华宏翻译后修饰Ë尾巴，重新定位相对于DNA核或组蛋白变体交换规范的组蛋白所必需的开花拟南芥5,6的适当调节。其中的一些染色质重塑活动催化沉积或除去的共价修饰，如乙酰化或甲基化的组蛋白的特定残基。这些组蛋白标记由该招募其他染色质重塑复合物，转录因子或转录机制的成分以调节开花的基因的转录活性专门效应特异性识别。 染色质免疫沉淀（ChIP）允许在体内的DNA结合位点的感兴趣的蛋白质（图1）的识别。这个过程利用了某些化学品的能力交联的蛋白质的DNA。得到的DNA蛋白质复合物可以通过使用特异性抗体来阿加然后免疫沉淀研究所转录因子，染色质结合蛋白，或特定变型和异源表位（通常被​​称为"标签"）附连到所选择的蛋白质。从这些免疫沉淀物进行纯化的DNA可以用作定量PCR（qPCR的）反应的模板，以评估所关注的特定序列的富集。以这种方式，转录因子的结合位点或在特定的基因组蛋白标记的分布可以建立7,8。此外，结合新一代测序（NGS），使大规模平行测序，芯片技术已经成为可能的转录因子结合位点，以及组蛋白修饰揭幕表观景观的全基因组的鉴定。此外，基因表达的同时分析可以监控转录调节如何结合或特定组蛋白标记的沉积相关的转录活性状况TY基因9。 利用拟南芥的ChIP协议允许评估的影响，多种转录调节因子有开花的主控基因的染色质组织，如何将这些结构变化影响基因表达5,6。以前的结果表明，拟南芥基因先期抽薹在短日照 （EBS）作为开花突变体中该基因节目开花和开花的FT的主基因的上调的加速度的阻遏。此外，丧失功能的突变的FT充分抑制EBS突变植物的早期开花表型，这表明FT需要EBS突变体的过早开花和EBS是必要的这个主开花10的基因的压制，11。EBS编码含有PHD-蛋白可以特异性结合组蛋白H3的二和三甲基在第Ë赖氨酸残基4（H3K4me2 / 3），这表明对EBS在FT 12的染色质介导的抑制的作用。使用该芯片的做法表明，拟南芥含有PHD蛋白EBS 10,11结合花卉积分FT基因的调控区，以抑制其表达12。通过使用芯片技术所获得的额外数据表明，该蛋白质是必需的，以保持在拟南芥发展初期低水平组蛋白乙酰化，活性转录的标志的，在这个主开花的基因的染色质。这些观察，连同遗传和基因表达数据，证明该拟南芥含有PHD-蛋白具有在开花时间的微调通过调制花香积分基因FT 12的表达的中心作用。这里提出的工作提供了优化的方法不仅对组蛋白的分析，但也可用于其他有用染色质相关蛋白质，和以更高的效率和降低的实验时间。此外，该报告说明了如何使用的ChIP协议提供了新的见解中染色质修饰改变和植物基因的转录状态之间的关系，以及如何将这些染色质介导的基因表达的控制影响的机制上开花拟南芥的发作。

<table border="0">
	<tbody>
		<tr>
			<td>MES</td>
			<td>Sigma</td>
			<td>M8250</td>
			<td></td>
		</tr>
		<tr>
			<td>MS (Murashige and Skoog Basal Salt Mixture)</td>
			<td>Sigma</td>
			<td>M5524</td>
			<td></td>
		</tr>
		<tr>
			<td>Formaldehyde 37%&#160;</td>
			<td>Sigma</td>
			<td>F8775-25</td>
			<td>Use under the fume hood</td>
		</tr>
		<tr>
			<td>Protease inhibitor mix cOmplete ULTRA Tablets, Mini, EDTA-free, EASYpack</td>
			<td>Roche</td>
			<td>5892791001</td>
			<td></td>
		</tr>
		<tr>
			<td>Bioruptor Standard sonication device</td>
			<td>Diagenode</td>
			<td>B01010002 (UCD200TO)</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Sigma</td>
			<td>50046</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick PCR Purification Kit</td>
			<td>Qiagen</td>
			<td>28104</td>
			<td></td>
		</tr>
		<tr>
			<td>Dynabeads&#174; magnetic beads coupled with protein A or protein G</td>
			<td>Life Technologies</td>
			<td>10003D/10001D</td>
			<td>Check manufacturer&#8217;s manual for antibody affinity</td>
		</tr>
		<tr>
			<td>Miracloth</td>
			<td>Merck Millipore</td>
			<td>475855</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton&#8482; X-100 Surfact-Amps&#8482; Detergent Solution</td>
			<td>Life Technologies</td>
			<td>85112</td>
			<td></td>
		</tr>
		<tr>
			<td>(mouse, rat, rabbit&#8230;)-IgG</td>
			<td>Diagenode</td>
			<td>C15400001, C15420001, C15410206</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic rack - DynaMag&#8482;-2</td>
			<td>Life Technologies</td>
			<td>12321D</td>
			<td></td>
		</tr>
		<tr>
			<td>H3K9/14ac polyclonal antibody - Premium&#160;</td>
			<td>Diagenode</td>
			<td>C15410200-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Chelex&#174; 100 Resin</td>
			<td>Bio-Rad</td>
			<td>142-2832</td>
			<td></td>
		</tr>
		<tr>
			<td>Proteinase K</td>
			<td>Life Technologies</td>
			<td>17916</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Myc Tag Antibody, clone 4A6</td>
			<td>Millipore</td>
			<td>05-724</td>
			<td></td>
		</tr>
		<tr>
			<td>LightCycler&#174; 480 SYBR Green I Master</td>
			<td>Roche</td>
			<td>4707516001</td>
			<td></td>
		</tr>
	</tbody>
</table>

chromatin immunoprecipitation assay for the identification of arabidopsis protein-dna interactions in vivo

Intricate gene regulatory networks orchestrate biological processes and developmental transitions in plants. Selective transcriptional activation and silencing of genes mediate the response of plants to environmental signals and developmental cues. Therefore, insights into the mechanisms that control plant gene expression are essential to gain a deep understanding of how biological processes are regulated in plants. The chromatin immunoprecipitation (ChIP) technique described here is a procedure to identify the DNA-binding sites of proteins in genes or genomic regions of the model species Arabidopsis thaliana. The interactions with DNA of proteins of interest such as transcription factors, chromatin proteins or posttranslationally modified versions of histones can be efficiently analyzed with the ChIP protocol. This method is based on the fixation of protein-DNA interactions in vivo, random fragmentation of chromatin, immunoprecipitation of protein-DNA complexes with specific antibodies, and quantification of the DNA associated with the protein of interest by PCR techniques. The use of this methodology in Arabidopsis has contributed significantly to unveil transcriptional regulatory mechanisms that control a variety of plant biological processes. This approach allowed the identification of the binding sites of the Arabidopsis chromatin protein EBS to regulatory regions of the master gene of flowering FT. The impact of this protein in the accumulation of particular histone marks in the genomic region of FT was also revealed through ChIP analysis.

八个主要步骤可以单挑在此芯片协议用 ​​于体内蛋白-DNA相互作用，包括生长和收获的植物材料，交联的染色质的，染色质隔离，染色质片段化，DNA和之间的复合物的选择性分离的的识别通过免疫沉淀，蛋白质消化，DNA纯化，和qPCR分析（图1）感兴趣的蛋白质。在芯片协议的一个关键步骤是DNA-蛋白质相互作用的交联反应进行固定。典型地，甲醛交联是用在植物沉淀。甲醛穿透...

Watch this Scientific Journal Video about Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo at JoVE.com

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

染色质免疫沉淀是一 ​​个功能强大的技术的DNA结合蛋白拟南芥的体内位点的鉴定。此过程包括染色质交联和碎裂，免疫沉淀与针对感兴趣的蛋白的选择性抗体，和结合的DNA的定量PCR分析。我们描述了拟南芥植物优化的一个简单的ChIP实验。

染色质免疫沉淀拟南芥蛋白-DNA相互作用的鉴定<em&gt;在体内</em

Intricate gene regulatory networks orchestrate biological processes and developmental transitions in plants. Selective transcriptional activation and ...

chromatin-immunoprecipitation-assay-for-identification-arabidopsis

Research

JoVE Journal

Biology

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

20.3K 次观看.  Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)-Universidad Politécnica de Madrid. 染色质免疫沉淀是一 ​​个功能强大的技术的DNA结合蛋白拟南芥的体内位点的鉴定。此过程包括染色质交联和碎裂，免疫沉淀与针对感兴趣的蛋白的选择性抗体，和结合的DNA的定量PCR分析。我们描述了拟南芥植物优化的一个简单的ChIP实验。 

视频: Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo

A Chromatin Assay for Human Brain Tissue

Chronic neuropsychiatric illnesses such as schizophrenia, bipolar disease and autism are thought to result from a combination of genetic and environmental factors that might result in epigenetic alterations of gene expression and other molecular pathology. Traditionally, however, expression studies in postmortem brain were confined to quantification of mRNA or protein. The limitations encountered in postmortem brain research   such as variabilities in autolysis time and tissue integrities   are also likely to impact any studies of higher order chromatin structures. However, the nucleosomal organization of genomic DNA   including DNA:core histone binding - appears to be largely preserved in representative samples provided by various brain banks. Therefore, it is possible to study the methylation pattern and other covalent modifications of the core histones at defined genomic loci in postmortem brain. Here, we present a simplified native chromatin immunoprecipitation (NChIP) protocol for frozen (never-fixed) human brain specimens. Starting with micrococcal nuclease digestion of brain homogenates, NChIP followed by qPCR can be completed within three days. The methodology presented here should be useful to elucidate epigenetic mechanisms of gene expression in normal and diseased human brain.

Until recently, expression studies on human brain were limited to quantification of RNA or protein. With the chromatin immunoprecipitation techniques described in this paper, it will be possible to map histone methylation and other epigenetic regulators of gene expression in postmortem brain.

一个人脑组织中的染色质含量

Chronic neuropsychiatric illnesses such as schizophrenia, bipolar disease and autism are thought to result from a combination of genetic and environmental ...

科研

生物学

Chromatin Immunoprecipitation from Human Embryonic Stem Cells

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are characterized by two fundamental properties: self-renewal and multipotency that allows a stem cell to differentiate into virtually any cell type 1. The progression stem cell to differentiated cell is characterized by loss of multipotency, structural and morphological changes and the hierarchic activity of transcription factors and signaling molecules, whose activities establish and maintain cell-type specific gene expression patterns. At the molecular level, cell differentiation involves dynamic changes of the structure and composition of chromatin and the detection of those dynamic changes can provide valuable insights into the functional features of stem cells and the cell differentiation process 2,3. Chromatin is a highly compacted DNA-protein complex that forms when cells package chromosomal DNA with proteins, mainly histones 4. Stemcellness and cell differentiation has been correlated with the presence of specific arrays of regulatory proteins such as epigenetic factors, histone variants, and transcription factors 2,3,5.
 Chromatin immunoprecipitation (ChIP) provides a valuable method to monitor the presence of RNA, proteins, and protein modifications in chromatin 6,7. The comparison of chromatin from different cell types can elucidate dynamic changes in protein-chromatin associations that occur during cell differentiation.
Chromatin immunoprecipitation involves the purification of in vivo cross-linked chromatin. The isolated chromatin is reduced to smaller fragments by enzymatic digestion or mechanical force. Chromatin fragments are precipitated using specific antibodies to target proteins or protein and DNA modifications. The precipitated DNA or RNA is purified and used as a template for PCR or DNA microarray based assays. Prerequisites for a successful ChIP are high quality antibodies to the desired antigen and the availability of chromatin from control cells that do not express the target molecule. ChIP can correlate the presence of proteins, protein and RNA modifications, and RNA with specific target DNA, and depending on the choice of outread tool, detects the association of target molecules at specific target genes or in the context of an entire genome. The comparison of the distribution of proteins in the chromatin of differentiating cells can elucidate the dynamic changes of chromatin composition that coincide with the progression of cells along a cell lineage.

The differentiation of ESC coincides with cell-type specific changes in the structure and composition of chromatin. The detection of those changes provides valuable insights into the mechanisms that define stemcellness and cell differentiation. Chromatin immunoprecipitation (ChIP) represents a valuable method to dissect the molecular mechanisms underlying stem cell differentiation.

从人类胚胎干细胞的染色质免疫沉淀

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are ...

Chromatin Immunoprecipitation (ChIP) to Assay Dynamic Histone Modification in Activated Gene Expression in Human Cells

In response to a variety of extracellular ligands, the STAT (signal transducer and activator of transcription) transcription factors are rapidly recruited from their latent state in the cytoplasm to cell surface receptors where they are activated by phosphorylation at a single tyrosine residue1. They then dimerize and translocate to the nucleus to drive the transcription of target genes, affecting growth, differentiation, homeostasis and the immune response. Not surprisingly, given their widespread involvement in normal cell processes, dysregulation of STAT function contributes to human disease, particularly to cancers2 and autoimmune diseases3. It is well established that transcription is regulated by alterations to the chromatin template4,5. These alterations include the activities of ATP-dependent complexes, as well as covalent histone modifications and DNA methylation6. Because STAT activation of gene expression is both rapid and transient, it requires specific mechanisms for modulating the chromatin template at STAT-dependent gene loci. To define these mechanisms, we characterize the histone modifications and the enzymatic activities that generate them at gene loci that respond to STAT signaling. This protocol describes chromatin immunoprecipitation, a method that is valuable for the study of STAT signaling to chromatin in activated gene expression.

Chromatin Immunoprecipitation ChIP to Assay Dynamic Histone Modification in Activated Gene Expression in Human Cells

This protocol describes how chromatin immunoprecipitation (ChIP) is used to study the dynamic alterations to the chromatin template that regulate transcription induced by a signal transduction pathway.

在激活人类细胞中的基因表达的动态检测组蛋白修饰染色质免疫沉淀（ChIP）

In response to a variety of extracellular ligands, the STAT (signal transducer and activator of transcription) transcription factors are rapidly recruited ...

Chromatin Immunoprecipitation Assay for Tissue-specific Genes using Early-stage Mouse Embryos

Chromatin immunoprecipitation (ChIP) is a powerful tool to identify protein:chromatin interactions that occur in the context of living cells 1-3. This technique has been widely exploited in tissue culture cells, and to a lesser extent, in primary tissue. The application of ChIP to rodent embryonic tissue, especially at early times of development, is complicated by the limited amount of tissue and the heterogeneity of cell and tissue types in the embryo. Here we present a method to perform ChIP using a dissociated embryonic day 8.5 (E8.5) embryo. Sheared chromatin from a single E8.5 embryo can be divided into up to five aliquots, which allows the investigator sufficient material for controls and for investigation of specific protein:chromatin interactions.
We have utilized this technique to begin to document protein:chromatin interactions during the specification of tissue-specific gene expression programs. The heterogeneity of cell types in an embryo necessarily restricts the application of this technique because the result is the detection of protein:chromatin interactions without distinguishing whether the interactions occur in all, a subset of, or a single cell type(s). However, examination of tissue-specific genes during or following the onset of tissue-specific gene expression is feasible for two reasons. First, immunoprecipitation of tissue specific factors necessarily isolates chromatin from the cell type where the factor is expressed. Second, immunoprecipitation of coactivators and histones containing post-translational modifications that are associated with gene activation should only be found at genes and gene regulatory sequences in the cell type where the gene is being or has been activated. The technique should be applicable to the study of most tissue-specific gene activation events.
In the example described below, we utilized E8.5 and E9.5 mouse embryos to examine factor binding at a skeletal muscle specific gene promoter. Somites, which are the precursor tissues from which the skeletal muscles of the trunk and limbs will form, are present at E8.5-9.54,5. Myogenin is a regulatory factor required for skeletal muscle differentiation 6-9. The data demonstrate that myogenin is associated with its own promoter in E8.5 and E9.5 embryos. Because myogenin is only expressed in somites at this stage of development 6,10, the data indicate that myogenin interactions with its own promoter have already occurred in skeletal muscle precursor cells in E8.5 embryos.

We demonstrate a chromatin immunoprecipitation (ChIP) method to identify factor interactions at tissue-specific genes during or after the onset of tissue-specific gene expression in mouse embryonic tissue. This protocol should be widely applicable for the study of tissue-specific gene activation as it occurs during normal embryonic development.

使用早期的小鼠胚胎组织特异性基因的染色质免疫沉淀检测

Chromatin immunoprecipitation (ChIP) is a powerful tool to identify protein:chromatin interactions that occur in the context of living cells 1-3. This ...

Chromatin Immunoprecipitation (ChIP) using Drosophila tissue

Epigenetics remains a rapidly developing field that studies how the chromatin state contributes to differential gene expression in distinct cell types at different developmental stages. Epigenetic regulation contributes to a broad spectrum of biological processes, including cellular differentiation during embryonic development and homeostasis in adulthood. A critical strategy in epigenetic studies is to examine how various histone modifications and chromatin factors regulate gene expression. To address this, Chromatin Immunoprecipitation (ChIP) is used widely to obtain a snapshot of the association of particular factors with DNA in the cells of interest.
ChIP technique commonly uses cultured cells as starting material, which can be obtained in abundance and homogeneity to generate reproducible data. However, there are several caveats: First, the environment to grow cells in Petri dish is different from that in vivo, thus may not reflect the endogenous chromatin state of cells in a living organism. Second, not all types of cells can be cultured ex vivo. There are only a limited number of cell lines, from which people can obtain enough material for ChIP assay.
Here we describe a method to do ChIP experiment using Drosophila tissues. The starting material is dissected tissue from a living animal, thus can accurately reflect the endogenous chromatin state. The adaptability of this method with many different types of tissue will allow researchers to address a lot more biologically relevant questions regarding epigenetic regulation in vivo1, 2. Combining this method with high-throughput sequencing (ChIP-seq) will further allow researchers to obtain an epigenomic landscape.

Chromatin Immunoprecipitation ChIP using Drosophila tissue

Recently high-throughput sequencing technology has greatly increased sensitivity of Chromatin Immunoprecipitation (ChIP) experiment and prompted its application using purified cells or dissected tissue. Here we delineate a method to use ChIP technique with Drosophila tissue, which can address the endogenous chromatin state in a well-characterized biological system.

染色质免疫沉淀（ChIP）使用果蝇组织

Epigenetics remains a rapidly developing field that studies how the chromatin state contributes to differential gene expression in distinct cell types at ...

A Protocol for the Identification of Protein-protein Interactions Based on 15N Metabolic Labeling, Immunoprecipitation, Quantitative Mass Spectrometry and Affinity Modulation

Protein-protein interactions are fundamental for many biological processes in the cell. Therefore, their characterization plays an important role in current research and a plethora of methods for their investigation is available1. Protein-protein interactions often are highly dynamic and may depend on subcellular localization, post-translational modifications and the local protein environment2. Therefore, they should be investigated in their natural environment, for which co-immunoprecipitation approaches are the method of choice3. Co-precipitated interaction partners are identified either by immunoblotting in a targeted approach, or by mass spectrometry (LC-MS/MS) in an untargeted way. The latter strategy often is adversely affected by a large number of false positive discoveries, mainly derived from the high sensitivity of modern mass spectrometers that confidently detect traces of unspecifically precipitating proteins. A recent approach to overcome this problem is based on the idea that reduced amounts of specific interaction partners will co-precipitate with a given target protein whose cellular concentration is reduced by RNAi, while the amounts of unspecifically precipitating proteins should be unaffected. This approach, termed QUICK for QUantitative Immunoprecipitation Combined with Knockdown4, employs Stable Isotope Labeling of Amino acids in Cell culture (SILAC)5 and MS to quantify the amounts of proteins immunoprecipitated from wild-type and knock-down strains. Proteins found in a 1:1 ratio can be considered as contaminants, those enriched in precipitates from the wild type as specific interaction partners of the target protein. Although innovative, QUICK bears some limitations: first, SILAC is cost-intensive and limited to organisms that ideally are auxotrophic for arginine and/or lysine. Moreover, when heavy arginine is fed, arginine-to-proline interconversion results in additional mass shifts for each proline in a peptide and slightly dilutes heavy with light arginine, which makes quantification more tedious and less accurate5,6. Second, QUICK requires that antibodies are titrated such that they do not become saturated with target protein in extracts from knock-down mutants.
Here we introduce a modified QUICK protocol which overcomes the abovementioned limitations of QUICK by replacing SILAC for 15N metabolic labeling and by replacing RNAi-mediated knock-down for affinity modulation of protein-protein interactions. We demonstrate the applicability of this protocol using the unicellular green alga Chlamydomonas reinhardtii as model organism and the chloroplast HSP70B chaperone as target protein7 (Figure 1). HSP70s are known to interact with specific co-chaperones and substrates only in the ADP state8. We exploit this property as a means to verify the specific interaction of HSP70B with its nucleotide exchange factor CGE19.

A Protocol for the Identification of Protein-protein Interactions Based on 15N Metabolic Labeling, Immunoprecipitation, Quantitative Mass Spectrometry and Affinity Modulation

We present a variation of the QUICK (QUantitative Immunoprecipitation Combined with Knockdown) approach that was introduced previously to distinguish between true and false protein-protein interactions. Our approach is based on 15N metabolic labeling, the modulation of affinities of protein-protein interactions by the presence/absence of ATP, immunoprecipitation, and quantitative mass spectrometry.

一个协议，用于基于蛋白质 - 蛋白质相互作用的鉴定<sup&gt; 15</sup&gt; N代谢标记，免疫沉淀法，的定量质谱法和亲和调制

Protein-protein interactions are fundamental for many biological processes in the cell. Therefore, their characterization plays an important role in ...

Efficient Chromatin Immunoprecipitation using Limiting Amounts of Biomass

Chromatin immunoprecipitation (ChIP) is a widely-used method for determining the interactions of different proteins with DNA in chromatin of living cells. Examples include sequence-specific DNA binding transcription factors, histones and their different modification states, enzymes such as RNA polymerases and ancillary factors, and DNA repair components. Despite its ubiquity, there is a lack of up-to-date, detailed methodologies for both bench preparation of material and for accurate analysis allowing quantitative metrics of interaction. Due to this lack of information, and also because, like any immunoprecipitation, conditions must be re-optimized for new sets of experimental conditions, the ChIP assay is susceptible to inaccurate or poorly quantitative results.
Our protocol is ultimately derived from seminal work on transcription factor:DNA interactions1,2 , but incorporates a number of improvements to sensitivity and reproducibility for difficult-to-obtain cell types. The protocol has been used successfully3,4 , both using qPCR to quantify DNA enrichment, or using a semi-quantitative variant of the below protocol.
This quantitative analysis of PCR-amplified material is performed computationally, and represents a limiting factor in the assay. Important controls and other considerations include the use of an isotype-matched antibody, as well as evaluation of a control region of genomic DNA, such as an intergenic region predicted not to be bound by the protein under study (or anticipated not to show changes under the experimental conditions). In addition, a standard curve of input material for every ChIP sample is used to derive absolute levels of enrichment in the experimental material. Use of standard curves helps to take into account differences between primer sets, regardless of how carefully they are designed, and also efficiency differences throughout the range of template concentrations for a single primer set. Our protocol is different from others that are available5-8 in that we extensively cover the later, analysis phase.

We describe a robust method for chromatin immunoprecipitation using primary T cells. The method is founded on standard approaches, but uses a specific set of conditions and reagents that improve efficiency for limited a quantities of cells. Importantly, a detailed description of the data analysis phase is presented.

生物质的使用限制金额高效的染色质免疫沉淀

Chromatin immunoprecipitation (ChIP) is a  widely-used method for determining the interactions of different proteins with  DNA in chromatin of living ...

Combining Single-molecule Manipulation and Imaging for the Study of Protein-DNA Interactions

The paper describes the combination of optical tweezers and single molecule fluorescence detection for the study of protein-DNA interaction. The method offers the opportunity of investigating interactions occurring in solution (thus avoiding problems due to closeby surfaces as in other single molecule methods), controlling the DNA extension and tracking interaction dynamics as a function of both mechanical parameters and DNA sequence. The methods for establishing successful optical trapping and nanometer localization of single molecules are illustrated. We illustrate the experimental conditions allowing the study of interaction of lactose repressor (lacI), labeled with Atto532, with a DNA molecule containing specific target sequences (operators) for LacI binding. The method allows the observation of specific interactions at the operators, as well as one-dimensional diffusion of the protein during the process of target search. The method is broadly applicable to the study of protein-DNA interactions but also to molecular motors, where control of the tension applied to the partner track polymer (for example actin or microtubules) is desirable.

Here we describe the instrumentation and methods for detecting single fluorescently-labeled protein molecules interacting with a single DNA molecule suspended between two optically trapped microspheres.

结合单分子操纵和成像蛋白-DNA相互作用的研究

The paper describes the combination of optical tweezers and single molecule fluorescence detection for the study of protein-DNA interaction. The method ...

Isolation of Specific Genomic Regions and Identification of Associated Molecules by enChIP

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the functions of these regions. To enable the non-biased identification of molecules interacting with a specific genomic region of interest, we recently developed the engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) technique. Here, we describe how to use enChIP to isolate specific genomic regions and identify the associated proteins and RNAs. First, a genomic region of interest is tagged with a transcription activator-like (TAL) protein or a clustered regularly interspaced short palindromic repeats (CRISPR) complex consisting of a catalytically inactive form of Cas9 and a guide RNA. Subsequently, the chromatin is crosslinked and fragmented by sonication. The tagged locus is then immunoprecipitated and the crosslinking is reversed. Finally, the proteins or RNAs that are associated with the isolated chromatin are subjected to mass spectrometric or RNA sequencing analyses, respectively. This approach allows the successful identification of proteins and RNAs associated with a genomic region of interest.

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the functions of these regions. This protocol describes procedures to perform engineered DNA-binding molecule-mediated chromatin imunoprecipitation (enChIP) for identification of proteins and RNAs associated with a specific genomic region.

具体的基因组区域及相关分子鉴定enChIP隔离

The identification of molecules associated with specific genomic regions of interest is required to understand the mechanisms of regulation of the ...

Genome-wide Mapping of Drug-DNA Interactions in Cells with COSMIC (Crosslinking of Small Molecules to Isolate Chromatin)

The genome is the target of some of the most effective chemotherapeutics, but most of these drugs lack DNA sequence specificity, which leads to dose-limiting toxicity and many adverse side effects. Targeting the genome with sequence-specific small molecules may enable molecules with increased therapeutic index and fewer off-target effects. N-methylpyrrole/N-methylimidazole polyamides are molecules that can be rationally designed to target specific DNA sequences with exquisite precision. And unlike most natural transcription factors, polyamides can bind to methylated and chromatinized DNA without a loss in affinity. The sequence specificity of polyamides has been extensively studied in vitro with cognate site identification (CSI) and with traditional biochemical and biophysical approaches, but the study of polyamide binding to genomic targets in cells remains elusive. Here we report a method, the crosslinking of small molecules to isolate chromatin (COSMIC), that identifies polyamide binding sites across the genome. COSMIC is similar to chromatin immunoprecipitation (ChIP), but differs in two important ways: (1) a photocrosslinker is employed to enable selective, temporally-controlled capture of polyamide binding events, and (2) the biotin affinity handle is used to purify polyamide&#8211;DNA conjugates under semi-denaturing conditions to decrease DNA that is non-covalently bound. COSMIC is a general strategy that can be used to reveal the genome-wide binding events of polyamides and other genome-targeting chemotherapeutic agents.

Genome-wide Mapping of Drug-DNA Interactions in Cells with COSMIC Crosslinking of Small Molecules to Isolate Chromatin

Identifying the direct targets of genome-targeting molecules remains a major challenge. To understand how DNA-binding molecules engage the genome, we developed a method that relies on crosslinking of small molecules to isolate chromatin (COSMIC).

染色质免疫沉淀拟南芥蛋白-DNA相互作用的鉴定

摘要

探索更多视频

此视频中的章节