This work was supported by grants from the Novartis Foundation for Medical-Biological Research and from the Research Pool of the University of Fribourg (to MW). We thank Li Zhao, Zhan Xu, and Solange Kharoubi Hess for technical support, as well as Radu Aricescu and Yvonne Jones (Oxford University, UK) for providing the pHLsec plasmid, and Thomas Sch&#252;rpf (Harvard Medical School) for helpful discussions.

1.生产表达质粒pHLsec-GZM的<ol><li>从人NK细胞制备总RNA用合适的RNA分离的方法和使用第一链cDNA合成试剂盒反转录（在26或NK细胞系的NK-92表达所有五个人类Gzms制备为原代细胞），继manufacturer`的建议。使用GZM基因PCR和克隆到pHLsec在23（拉杜Aricescu和伊冯·琼斯，英国牛津大学样的礼物）描述使用AGEI和KpnI位点（ 图1）放大。 注意：使用在表1所示的以下引物。 </li><li>确认无误后插入测序。展开DH5α细胞中的表达质粒和净化使用无内毒素质粒提取试剂盒，并按照制造商的说明。 </li><li>重悬在无内毒素的无菌水的纯化的质粒以2mg / ml和商店的浓度在-20℃until采用。 </li></ol> Gzms在HEK293T细胞2.表达<ol><li>试剂的制备<ol><li>制备标准培养基。以Dulbecco氏改良的Eagle培养基（DMEM）含有高葡萄糖（25毫米），Glutamax的（4毫摩尔），丙酮酸钠（1mM的）添加标准胎牛血清（FCS），青霉素（100单位/ ml），链霉素10％（ 100微克/毫升）。 </li><li>准备转染培养基。而不青霉素 - 链霉素的培养基中添加25微克/ ml的氯喹（在转染当天，从1000倍的股票在PBS，储存在-20℃下添加新鲜）。 </li><li>制备无血清培养基：向无血清培养基中的HEK293细胞中添加谷氨酰胺（4毫摩尔），青霉素（100单位/ ml），链霉素（100微克/毫升），并为2.5mg / L的两性霉素B. </li><li>准备使用前于表2和过滤器描述了一个0.45微米的过滤器的解决方案： </li></ol></li><li>扩大HEK293T细胞<ol><li>成长HEK293T细胞20毫升崇拜采用150×25mm的组织培养皿中茜。 </li><li>在80％汇合分裂细胞（分比为1：4，通常每3天）。细胞松散连接，它们可通过严格上下抽吸被机械分离的无胰蛋白酶消化。 </li><li>板的细胞转染的前一天晚上，得到60-70％汇合在转染（接种密度〜2×10 5个细胞/ ml）的一天。通常制剂规模由20至25培养皿。 </li></ol></li><li>磷酸钙转染<ol><li> 1小时转染前，改变标准培养基到20ml转染培养基。邻近的这1小时温育步骤结束时，混合400微克质粒DNA与10.95毫升双蒸2 O和在50ml试管1.55毫升2M 氯化钙 （1管/ 5菜）。 </li><li> 1至2之前转染分钟，添加12.5毫升2×HBS到12.5的DNA的钙溶液的毫升，由管倒置混合和温育30秒，在室温。 </li><li>第添加ë混合物直接加入细胞（每皿5毫升）逐滴入培养基制备2.3.2。均匀地洒在整个区域，把介质到浅橙色的颜色。 </li><li>孵育培养皿为7至11小时，在组织培养恒温箱（37℃，5％CO 2的湿润空气）。培养后，微细的析出物是可见的。移除转染介质，用预热的PBS小心冲洗并加入2.1.3制备20毫升无血清培养基中。孵育72小时在组织培养箱。 </li><li>通过运行在SDS-PAGE的细胞上清液的样品（约20微升）和用考马斯亮蓝染色来可视化颗粒酶带分析的转染和表达效率。 </li></ol></li><li>净化Gzms从培养上清镍IMAC <ol><li>培养后，弃去细胞的培养物上清液加到250ml试管并离心清晰。开展第一自旋（400 XG，10分钟，4℃C），将清除介质从分离的细胞。转移在新鲜250毫升管和自旋上清液以4000×g离心，30分钟，在4℃以除去任何残留的细胞碎片。 </li><li>加入5毫升5 M氯化钠，6.25毫升0.25M的制备NiSO 4的2M Tris碱（pH 8）中和1毫升每250毫升清除上清液。使用500ml的真空过滤器单元（0.45毫米）过滤上清。 </li><li>平衡使用合适的FPLC系统镍IMAC柱与他的结合缓冲液A（10柱体积，CV）。 </li><li>以0.5毫升/分钟，在4℃的流速施加的澄清的上清液到平衡柱。 </li><li>上清液施加之后，直到UV吸收基线达到（通常为10 CV）与他的结合缓冲液洗柱。 </li><li>洗脱Gzms具有线性20毫升梯度（0至250mM咪唑）以0.5毫升/分钟流速，同时收集2毫升的级分。分析洗脱的级分通过SDS-PAGE和考马斯染色。 </li></ol></li><li>肠激酶（EK）处理和最终的清理通过阳离子交换层析<ol><li>游泳池GZM包含在透析管≤10截留分子量组分。储存在-20℃的小样本作为预EK控制。 </li><li>在0.02单位/50毫升初始上清液添加EK直接向汇集馏分在透析管中透析O / N（至少16小时）在RT在EK-缓冲器（4L，改变缓冲一次）。 </li><li>第二天，分析EK在相比于预EK控制通过SDS-PAGE和考马斯染色处理Gzms。 </li><li>当N-末端处理完成后，改变透析缓冲至S缓冲液A（4 L）和透析另外4小时，在室温。透析过滤（0.45微米）。 </li><li>平衡一个的S-柱带有S缓冲液A与加载样品上柱以0.5ml /分钟，在4℃的流速。 </li><li>样后，直到紫外吸收基线达到（约10 CV）洗带S缓冲液A柱。洗脱Gzms用30ml的线性梯度（150〜1000毫摩尔NaCl）。 GzmAê在琵琶〜650毫米氯化钠，在GZMB〜700毫米氯化钠和GzmM在〜750毫米氯化钠。 </li><li>分析洗脱的级分通过SDS-PAGE和比色测定法（见下文）。含有Gzms和浓缩池级分（约30倍，至约100μM的浓度）的自旋过滤器（15毫升，10 MWCO）。分装浓GZM准备并储存在-80℃。 </li></ol></li></ol> 3.测试GZM活动<ol><li>试剂的制备<ol><li>制备比色测定缓冲液：50毫摩尔Tris-基地，pH为7。 <ol><li>为GzmA的测量，添加的Na-CBZ-L-赖氨酸苄硫基酯（S-BZL）（BLT）的测定缓冲液以0.2毫和5,5&#39;-二硫代双（2-硝基苯甲酸）的终浓度（DTNB），以0.22毫浓度。对于GZMB，包括0.2毫米的Boc - 丙氨酸 - 丙氨酸 - 天冬氨酸 - S-BZL（AAD）和0.22毫DTNB。对于GzmM，包括0.2毫米SUC-丙氨酸 - 丙氨酸 - 脯氨酸 - 亮氨酸对硝基苯胺（PNA）（AAPL）。合成肽是由适当的储备溶液中加入（在DMSO中，保存位置编在-20℃）到缓冲新鲜的测定之前。 </li></ol></li><li>制备裂解测定缓冲液：100mM NaCl的50毫摩尔Tris-碱，pH 7.5 </li></ol></li><li>比色法<ol><li>分发来自洗脱份小样本GZM（&lt;5μL）或个股集中在96孔平底板。包括一个阳性对照组（测试GZM制剂或粗NK细胞裂解液）和阴性对照（只缓冲）。 </li><li>加入100微升测定缓冲液到每个孔中（使用多通道移液器）。孵育10分钟，在37℃。测量的OD在酶标仪405nm处。 </li></ol></li><li>切割测定法<ol><li>为使用纯化的底物裂解测定法，共孵育的蛋白质底物（天然的或重组的，100 - 400纳米;高效GZM衬底的几个例子将在本节的末尾呈现在结果部分，并在注）与连续稀释的一个GZM在不同时间测定缓冲液（起始于400纳米）。通过SDS-PAGE和考马斯或银染色分析;或者通过免疫印迹使用特异性抗体。 </li><li>对于使用细胞裂解物裂解测定法，悬浮在1ml分析缓冲液和裂解10 6个HeLa细胞（或任何可用的肿瘤细胞系）通过在37℃下三次在乙醇/干冰浴中解冻冷冻。通过离心（在4℃下15000×g离心10分钟）除去细胞碎片。 </li><li>共孵育澄清的裂解液与Gzms各种浓度和倍以上。切割是通过使用合适的抗体进行免疫印迹检测到。 注：国际棋联基板善意的几个例子商业抗体是其中可供选择：买入（BH3相互作用域死亡激动剂）和caspase 3由GZMB 27,28切割;多个异构核核糖（hnRNPA1，A2和U）由GzmA 29切割;巨细胞病毒磷71 GzmM 30。 </li></ol></li></ol>

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P., Lieberman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alterations+in+RNA+processing+during+immune-mediated+programmed+cell+death.">Alterations in RNA processing during immune-mediated programmed cell death.</a> Proc Natl Acad Sci U S A. 109, 8688-8693 (2012).</li><li>Domselaar, 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=Noncytotoxic+inhibition+of+cytomegalovirus+replication+through+NK+cell+protease+granzyme+M-mediated+cleavage+of+viral+phosphoprotein+71.">Noncytotoxic inhibition of cytomegalovirus replication through NK cell protease granzyme M-mediated cleavage of viral phosphoprotein 71.</a> J Immunol. 185, 7605-7613 (2010).</li><li>Thiery, 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=Perforin+activates+clathrin-+and+dynamin-dependent+endocytosis,+which+is+required+for+plasma+membrane+repair+and+delivery+of+granzyme+B+for+granzyme-mediated+apoptosis.">Perforin activates clathrin- and dynamin-dependent endocytosis, which is required for plasma membrane repair and delivery of granzyme B for granzyme-mediated apoptosis.</a> Blood. 115, 1582-1593 (2010).</li><li>Thiery, 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=Perforin+pores+in+the+endosomal+membrane+trigger+the+release+of+endocytosed+granzyme+B+into+the+cytosol+of+target+cells.">Perforin pores in the endosomal membrane trigger the release of endocytosed granzyme B into the cytosol of target cells.</a> Nat Immunol. 12, 770-777 (2011).</li><li>Thomas, M. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leukocyte+protease+binding+to+nucleic+acids+promotes+nuclear+localization+and+cleavage+of+nucleic+acid+binding+proteins.">Leukocyte protease binding to nucleic acids promotes nuclear localization and cleavage of nucleic acid binding proteins.</a> J Immunol. 192, 5390-5397 (2014).</li><li>Jacquemin, G., 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=Granzyme+B-induced+mitochondrial+ROS+are+required+for+apoptosis.">Granzyme B-induced mitochondrial ROS are required for apoptosis.</a> Cell death and differentiation. , (2014).</li><li>Kummer, J. A., Kamp, A. M., Citarella, F., Horrevoets, A. J., Hack, C. E. <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+human+recombinant+granzyme+A+zymogen+and+its+activation+by+the+cysteine+proteinase+cathepsin+C.">Expression of human recombinant granzyme A zymogen and its activation by the cysteine proteinase cathepsin C.</a> The Journal of biological chemistry. 271, 9281-9286 (1996).</li><li>Hagn, M., Sutton, V. R., Trapani, J. 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+colorimetric+assay+that+specifically+measures+Granzyme+B+proteolytic+activity:+hydrolysis+of+Boc-Ala-Ala-Asp-S-Bzl.">A colorimetric assay that specifically measures Granzyme B proteolytic activity: hydrolysis of Boc-Ala-Ala-Asp-S-Bzl.</a> Journal of visualized experiments : JoVE. , e52419 (2014).</li><li>Huang, M. T., Gorman, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intervening+sequences+increase+efficiency+of+RNA+3'+processing+and+accumulation+of+cytoplasmic+RNA.">Intervening sequences increase efficiency of RNA 3' processing and accumulation of cytoplasmic RNA.</a> Nucleic Acids Res. 18, 937-947 (1990).</li><li>Luthman, H., Magnusson, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+efficiency+polyoma+DNA+transfection+of+chloroquine+treated+cells.">High efficiency polyoma DNA transfection of chloroquine treated cells.</a> Nucleic Acids Res. 11, 1295-1308 (1983).</li><li>Magee, A. I., Grant, D. A., Hermon-Taylor, J., Offord, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specific+one-stage+method+for+assay+of+enterokinase+activity+by+release+of+radiolabelled+activation+peptides+from+alpha-N-[3H]acetyl-trypsinogen+and+the+effect+of+calcium+ions+on+the+enzyme+activity.">Specific one-stage method for assay of enterokinase activity by release of radiolabelled activation peptides from alpha-N-[3H]acetyl-trypsinogen and the effect of calcium ions on the enzyme activity.</a> Biochem J. 197, 239-244 (1981).</li></ol>

The authors have nothing to disclose.

GzmA和GZMB的经典和广泛研究的作用是诱导凋亡在哺乳动物细胞中的其胞质递送由所述孔形成蛋白PFN 1之后。最近，Gzms的细胞毒性谱显著从哺乳动物细胞扩大到细菌9,10，以及某些寄生虫11。此外，GzmA和GZMB的非经典，胞外功能以及各种孤儿Gzms的生物学意义仍不清楚。因此，Gzms的健壮时间和成本的高效表达和纯化系统中，通过该协议规定，将是对这些未来的研究有很大的帮助...

所述Gzms是一族局部存在的CTL专门溶酶体和NK细胞1高度同源的丝氨酸蛋白酶。这些杀伤细胞的细胞毒性颗粒还包含与膜破坏蛋白质PFN和GNLY被在识别去往消除2,3靶细胞的同时释放与Gzms。有五个Gzms在人类（GzmA，B，H，K和M），和10 Gzms小鼠（GzmA - G，K，M和N）。 GzmA和GZMB是最丰富的和广泛的研究在人类和小鼠1。然而，最近的研究已经开始研究细胞死亡途径以及由在健康和疾病4，另外，所谓孤儿Gzms介导的额外的生物效应。 该Gzms最著名的功能，特别是GzmA和GZMB的，是程序性细胞死亡在哺乳动物细胞中的诱导时由PFN 5,6-递送到靶细胞。然而，最近的研究还PFN 7,8展示了Gzms细胞外效应与免疫调节和炎症产生深远的影响，独立胞浆交付。这是在Gzms胞浆入境后有效地杀伤细胞的光谱也于近日从哺乳动物细胞扩大至9,10细菌，甚至某些寄生虫11。最近的这些发现开辟了一个全新的领域进行研究GZM。因此，经济高效，高产哺乳动物表达系统将显著缓解的方式为那些未来的研究。 天然人，小鼠和大鼠Gzms已成功地从CTL和NK细胞线12-14的颗粒级分纯化。然而，在我们手中的这样的纯化技术的产率小于0.1毫克/升细胞培养物（未发表的观测和12）的范围内。此外，单个GZM由诺特的色谱分离而不污染řGzms和/或蛋白质，也存在于该颗粒是具有挑战性（未公布的数据和12,14）。重组Gzms产生于细菌15，酵母16，昆虫细胞17和甚至在哺乳动物细胞如HEK 293 18,19。仅在哺乳动物表达系统承担产生重组酶具有相同于天然细胞毒性蛋白质的翻译后修饰的潜力。翻译后修饰已牵涉与通过内吞作用的特异性摄取和蛋白酶的靶细胞20-22内的细胞内定位。因此，通过使用pHLsec 23质粒骨干GZM表达（拉杜Aricescu和伊冯·琼斯，英国牛津大学一个样的礼物），我们建立了一个简单，时间和成本效益的系统，高产蛋白生产HEK293T细胞。 pHLsec结合CMV增强用鸡Β肌动蛋白启动子;在一起，这些元件demonstra泰德在各种细胞系24中的最强的启动子活性。此外，该质粒含有兔Β珠蛋白内含子，优化的Kozak和分泌信号，一个赖氨酸的6xHis标签和一个多聚A信号。插入可方便地分泌信号，并确保对缺乏适当的N-末端结构域的蛋白的最佳表达和分泌效率的赖氨酸的6xHis标签（ 图1）之间进行克隆。为Gzms的表达，我们换成由载体随后肠激酶（EK）的网站（DDDDK）提供的分泌信号内源分泌信号序列，使得EK治疗活化分泌Gzms（活性Gzms开始与N-末端氨基酸序列IIGG 25）。另外，在有利于该方法，HEK293T细胞在低价介质快速增长，如Dulbecco改进的Eagle培养基（DMEM），并且非常适合于成本效益的磷酸钙转染法。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>TRIzol Reagent</td>
			<td>Invitrogen</td>
			<td>15596-026</td>
			<td>Total RNA isolation kit</td>
		</tr>
		<tr>
			<td>SuperScript II Reverse Transcriptase</td>
			<td>Invitrogen</td>
			<td>18064-014</td>
			<td></td>
		</tr>
		<tr>
			<td>Phusion High-Fidelity DNA Polymerase</td>
			<td>NEB</td>
			<td>M0530L</td>
			<td></td>
		</tr>
		<tr>
			<td>EndoFree Plasmid Maxi Kit</td>
			<td>QIAGEN</td>
			<td>12362</td>
			<td></td>
		</tr>
		<tr>
			<td>EX-CELL 293 Serum-Free Medium for HEK 293 Cells</td>
			<td>Sigma</td>
			<td>14571C</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM, high glucose, GlutaMAX Supplement, pyruvate</td>
			<td>Gibco</td>
			<td>31966-021</td>
			<td></td>
		</tr>
		<tr>
			<td>SnakeSkin Dialysis Tubing, 10K MWCO</td>
			<td>Thermo Scientific</td>
			<td>68100</td>
			<td></td>
		</tr>
		<tr>
			<td>Enterokinase from bovine intestine</td>
			<td>Sigma</td>
			<td>E4906</td>
			<td>recombinant, &#8805;20&#160;units/mg protein</td>
		</tr>
		<tr>
			<td>HisTrap Excel 5ml-column</td>
			<td>GE Healthcare</td>
			<td>17-3712-06&#160;</td>
			<td>Nickel IMAC</td>
		</tr>
		<tr>
			<td>HiTrap SP HP 5 ml-column</td>
			<td>GE Healthcare</td>
			<td>17-1152-01&#160;</td>
			<td>S column</td>
		</tr>
		<tr>
			<td>N-&#945;-Cbz-L-lysine thiobenzylester (BLT)</td>
			<td>Sigma</td>
			<td>C3647</td>
			<td>GzmA substrate</td>
		</tr>
		<tr>
			<td>Boc-Ala-Ala-Asp-S-Bzl (AAD)</td>
			<td>MP Biomedicals</td>
			<td>2193608 _10mg</td>
			<td>GzmB substrate</td>
		</tr>
		<tr>
			<td>Suc-Ala-Ala-Pro-Leu-p-nitroanilide (AAPL)</td>
			<td>Bachem</td>
			<td></td>
			<td>GzmM substrate</td>
		</tr>
		<tr>
			<td>5,5&#8242;-dithio-bis(2-nitrobenzoic acid) (DTNB)</td>
			<td>Sigma</td>
			<td>D8130</td>
			<td>Ellman`s reagent</td>
		</tr>
	</tbody>
</table>

a high yield and cost-efficient expression system of human granzymes in mammalian cells

When cytotoxic T lymphocytes (CTL) or natural killer (NK) cells recognize tumor cells or cells infected with intracellular pathogens, they release their cytotoxic granule content to eliminate the target cells and the intracellular pathogen. Death of the host cells and intracellular pathogens is triggered by the granule serine proteases, granzymes (Gzms), delivered into the host cell cytosol by the pore forming protein perforin (PFN) and into bacterial pathogens by the prokaryotic membrane disrupting protein granulysin (GNLY). To investigate the molecular mechanisms of target cell death mediated by the Gzms in experimental in-vitro settings, protein expression and purification systems that produce high amounts of active enzymes are necessary. Mammalian secreted protein expression systems imply the potential to produce correctly folded, fully functional protein that bears posttranslational modification, such as glycosylation. Therefore, we used a cost-efficient calcium precipitation method for transient transfection of HEK293T cells with human Gzms cloned into the expression plasmid pHLsec. Gzm purification from the culture supernatant was achieved by immobilized nickel affinity chromatography using the C-terminal polyhistidine tag provided by the vector. The insertion of an enterokinase site at the N-terminus of the protein allowed the generation of active protease that was finally purified by cation exchange chromatography. The system was tested by producing high levels of cytotoxic human Gzm A, B and M and should be capable to produce virtually every enzyme in the human body in high yields.

在下面的部分中，我们将提出一个GzmA制剂的一个完整的文件照亮方法。我们还成功纯化GZMB和GzmM，在生产方面的净化效率和活动类似的结果。然而，从这些准备工作后，我们将只显示几个选定的数据块。从293T细胞按照目前的协议GZMB准备在几个已发表 ​​的研究中使用，突出了他们活动的各种生物检测系统9,29,31-34。 一个典型的GzmA纯化示于图2A中 。有效?...

Watch this Scientific Journal Video about A High Yield and Cost-efficient Expression System of Human Granzymes in Mammalian Cells at JoVE.com

A High Yield and Cost-efficient Expression System of Human Granzymes in Mammalian Cells

We describe here a cost-efficient granzyme expression system using HEK293T cells that produces high yields of pure, fully glycosylated and enzymatically active protease.

人类颗粒酶在哺乳动物细胞中高产量和经济高效表达系统

When cytotoxic T lymphocytes (CTL) or natural killer (NK) cells recognize tumor cells or cells infected with intracellular pathogens, they release their ...

a-high-yield-cost-efficient-expression-system-human-granzymes

Research

JoVE Journal

Biology

9.7K 次观看.  Boston Children’s Hospital and Harvard Medical School. We describe here a cost-efficient granzyme expression system using HEK293T cells that produces high yields of pure, fully glycosylated and enzymatically active protease. 

视频: A High Yield and Cost-efficient Expression System of Human Granzymes in Mammalian Cells

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

使用基因脉冲MXcell电穿孔系统主细胞的转染效率高

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

科研

生物学

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

使用自动细胞计数器简化基因表达研究：在Namalwa细胞的IL - 4依赖的基因表达的siRNA击倒

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

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 ...

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying potassium (referred to as GIRK) channels, which are important for regulating the excitability of neurons. There are four different mammalian GIRK channel subunits (GIRK1-GIRK4) - we focus on GIRK2 because it forms a homotetramer. Stimulation of different types of G protein-coupled receptors (GPCRs), such as the muscarinic receptor (M2R), leads to activation of GIRK channels. Alcohol also directly activates GIRK channels. We will show how to mutate one amino acid by specifically changing one or more nucleotides in the cDNA for the GIRK channel. This mutated cDNA sequence will be amplified in bacteria, purified, and the presence of the point mutation will be confirmed by DNA sequencing. The cDNAs for the mutated and wild-type GIRK channels will be transfected into human embryonic kidney HEK293T cells cultured in vitro. Lastly, whole-cell patch-clamp electrophysiology will be used to study the macroscopic potassium currents through the ectopically expressed wild-type or mutated GIRK channels. In this experiment, we will examine the effect of a L257W mutation in GIRK2 channels on M2R-dependent and alcohol-dependent activation.

We will demonstrate how to study the effect of a single point mutation on the function of an ion channel.

异源表达在哺乳动物细胞离子通道的突变和功能分析

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying ...

Absolute Quantum Yield Measurement of Powder Samples

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and research of illumination, AV equipment, organic EL material, films, filters and fluorescent probes for bio-industry.
Quantum yield is calculated as the ratio of the number of photons absorbed, to the number of photons emitted by a material. The higher the quantum yield, the better the efficiency of the fluorescent material.
For the measurements featured in this video, we will use the Hitachi F-7000 fluorescence spectrophotometer equipped with the Quantum Yield measuring accessory and Report Generator program. All the information provided applies to this system. 
Measurement of quantum yield in powder samples is performed following these steps:
<ol>
 <li>Generation of instrument correction factors for the excitation and emission monochromators. This is an important requirement for the correct measurement of quantum yield. It has been performed in advance for the full measurement range of the instrument and will not be shown in this video due to time limitations.</li>
 <li>Measurement of integrating sphere correction factors. The purpose of this step is to take into consideration reflectivity characteristics of the integrating sphere used for the measurements.</li>
 <li>Reference and Sample measurement using direct excitation and indirect excitation.</li>
 <li>Quantum Yield calculation using Direct and Indirect excitation. Direct excitation is when the sample is facing directly the excitation beam, which would be the normal measurement setup. However, because we use an integrating sphere, a portion of the emitted photons resulting from the sample fluorescence are reflected by the integrating sphere and will re-excite the sample, so we need to take into consideration indirect excitation. This is accomplished by measuring the sample placed in the port facing the emission monochromator, calculating indirect quantum yield and correcting the direct quantum yield calculation.</li>
 <li>Corrected quantum yield calculation.</li>
 <li>Chromaticity coordinates calculation using Report Generator program.</li>
</ol>
The Hitachi F-7000 Quantum Yield Measurement System offer advantages for this
application, as follows:
<ul>
 <li>High sensitivity (S/N ratio 800 or better RMS). Signal is the Raman band of water measured under the following conditions: Ex wavelength 350 nm, band pass Ex and Em 5 nm, response 2 sec), noise is measured at the maximum of the Raman peak. High sensitivity allows measurement of samples even with low quantum yield. Using this system we have measured quantum yields as low as 0.1 for a sample of salicylic acid and as high as 0.8 for a sample of magnesium tungstate.</li>
 <li>Highly accurate measurement with a dynamic range of 6 orders of magnitude allows for measurements of both sharp scattering peaks with high intensity, as well as broad fluorescence peaks of low intensity under the same conditions. </li>
 <li>High measuring throughput and reduced light exposure to the sample, due to a high scanning speed of up to 60,000 nm/minute and automatic shutter function. </li>
 <li>Measurement of quantum yield over a wide wavelength range from 240 to 800 nm.</li>
 <li>Accurate quantum yield measurements are the result of collecting instrument spectral response and integrating sphere correction factors before measuring the sample.</li>
 <li>Large selection of calculated parameters provided by dedicated and easy to use software.
</li>
</ul> 
During this video we will measure sodium salicylate in powder form which is known to have a quantum yield value of 0.4 to 0.5.

In this video we will demonstrate measuring and calculating absolute quantum yield and chromaticity coordinates directly in powder samples using the Hitachi F-7000 Quantum Yield Measuring System.

粉末样品的绝对量子产量测量

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and ...

Efficient Derivation of Human Cardiac Precursors and Cardiomyocytes from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based transplantation or by cardiac tissue engineering1-3. Cardiomyocytes become terminally-differentiated soon after birth and lose their ability to proliferate. There is no evidence that stem/progenitor cells derived from other sources, such as the bone marrow or the cord blood, are able to give rise to the contractile heart muscle cells following transplantation into the heart1-3. The need to regenerate or repair the damaged heart muscle has not been met by adult stem cell therapy, either endogenous or via cell delivery1-3. The genetically stable human embryonic stem cells (hESCs) have unlimited expansion ability and unrestricted plasticity, proffering a pluripotent reservoir for in vitro derivation of large supplies of human somatic cells that are restricted to the lineage in need of repair and regeneration4,5. Due to the prevalence of cardiovascular disease worldwide and acute shortage of donor organs, there is intense interest in developing hESC-based therapies as an alternative approach. However, how to channel the wide differentiation potential of pluripotent hESCs efficiently and predictably to a desired phenotype has been a major challenge for both developmental study and clinical translation. Conventional approaches rely on multi-lineage inclination of pluripotent cells through spontaneous germ layer differentiation, resulting in inefficient and uncontrollable lineage-commitment that is often followed by phenotypic heterogeneity and instability, hence, a high risk of tumorigenicity6-8 (see a schematic in Fig. 1A). In addition, undefined foreign/animal biological supplements and/or feeders that have typically been used for the isolation, expansion, and differentiation of hESCs may make direct use of such cell-specialized grafts in patients problematic9-11. To overcome these obstacles, we have resolved the elements of a defined culture system necessary and sufficient for sustaining the epiblast pluripotence of hESCs, serving as a platform for de novo derivation of clinically-suitable hESCs and effectively directing such hESCs uniformly towards clinically-relevant lineages by small molecules12 (see a schematic in Fig. 1B). After screening a variety of small molecules and growth factors, we found that such defined conditions rendered nicotinamide (NAM) sufficient to induce the specification of cardiomesoderm direct from pluripotent hESCs that further progressed to cardioblasts that generated human beating cardiomyocytes with high efficiency (Fig. 2). We defined conditions for induction of cardioblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human cardiac cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of cardioblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human cardiac progenitors and functional cardiomyocytes for cardiovascular repair.

高效的推导人类心脏的前体和从多能干的小分子诱导人类胚胎干细胞的心肌细胞

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based ...

Analysis of Cell Cycle Position in Mammalian Cells

The regulation of cell proliferation is central to tissue morphogenesis during the development of multicellular organisms. Furthermore, loss of control of cell proliferation underlies the pathology of diseases like cancer. As such there is great need to be able to investigate cell proliferation and quantitate the proportion of cells in each phase of the cell cycle. It is also of vital importance to indistinguishably identify cells that are replicating their DNA within a larger population. Since a cell&prime;s decision to proliferate is made in the G1 phase immediately before initiating DNA synthesis and progressing through the rest of the cell cycle, detection of DNA synthesis at this stage allows for an unambiguous determination of the status of growth regulation in cell culture experiments.
DNA content in cells can be readily quantitated by flow cytometry of cells stained with propidium iodide, a fluorescent DNA intercalating dye. Similarly, active DNA synthesis can be quantitated by culturing cells in the presence of radioactive thymidine, harvesting the cells, and measuring the incorporation of radioactivity into an acid insoluble fraction. We have considerable expertise with cell cycle analysis and recommend a different approach. We Investigate cell proliferation using bromodeoxyuridine/fluorodeoxyuridine (abbreviated simply as BrdU) staining that detects the incorporation of these thymine analogs into recently synthesized DNA. Labeling and staining cells with BrdU, combined with total DNA staining by propidium iodide and analysis by flow cytometry1 offers the most accurate measure of cells in the various stages of the cell cycle. It is our preferred method because it combines the detection of active DNA synthesis, through antibody based staining of BrdU, with total DNA content from propidium iodide. This allows for the clear separation of cells in G1 from early S phase, or late S phase from G2/M. Furthermore, this approach can be utilized to investigate the effects of many different cell stimuli and pharmacologic agents on the regulation of progression through these different cell cycle phases.
In this report we describe methods for labeling and staining cultured cells, as well as their analysis by flow cytometry. We also include experimental examples of how this method can be used to measure the effects of growth inhibiting signals from cytokines such as TGF-&beta;1, and proliferative inhibitors such as the cyclin dependent kinase inhibitor, p27KIP1. We also include an alternate protocol that allows for the analysis of cell cycle position in a sub-population of cells within a larger culture5. In this case, we demonstrate how to detect a cell cycle arrest in cells transfected with the retinoblastoma gene even when greatly outnumbered by untransfected cells in the same culture. These examples illustrate the many ways that DNA staining and flow cytometry can be utilized and adapted to investigate fundamental questions of mammalian cell cycle control.

Determining the cell cycle position of a population of cells, or understanding how signals affect proliferation, can be readily measured by flow cytometry using this protocol. We report a simple experimental approach to staining cells and quantifying their position in the cell cycle.

在哺乳动物细胞中细胞周期位置分析

The regulation of cell proliferation is central to tissue morphogenesis during the development of multicellular organisms. Furthermore, loss of control of ...

Expression Analysis of Mammalian Linker-histone Subtypes

Linker histone H1 binds to the nucleosome core particle and linker DNA, facilitating folding of chromatin into higher order structure. H1 is essential for mammalian development1 and regulates specific gene expression in vivo2-4. Among the highly conserved histone proteins, the family of H1 linker histones is the most heterogeneous group. There are 11 H1 subtypes in mammals that are differentially regulated during development and in different cell types. These H1 subtypes include 5 somatic H1s (H1a-e), the replacement H10, 4 germ cell specific H1 subtypes, and H1x5. The presence of multiple H1 subtypes that differ in DNA binding affinity and chromatin compaction ability6-9 provides an additional level of modulation of chromatin function. Thus, quantitative expression analysis of individual H1 subtypes, both of mRNA and proteins, is necessary for better understanding of the regulation of higher order chromatin structure and function.
Here we describe a set of assays designed for analyzing the expression levels of individual H1 subtypes (Figure 1). mRNA expression of various H1 variant genes is measured by a set of highly sensitive and quantitative reverse transcription-PCR (qRT-PCR) assays, which are faster, more accurate and require much less samples compared with the alternative approach of Northern blot analysis. Unlike most other cellular mRNA messages, mRNAs for most histone genes, including the majority of H1 genes, lack a long polyA tail, but contain a stem-loop structure at the 3' untranslated region (UTR)10. Therefore, cDNAs are prepared from total RNA by reverse transcription using random primers instead of oligo-dT primers. Realtime PCR assays with primers specific to each H1 subtypes (Table 1) are performed to obtain highly quantitative measurement of mRNA levels of individual H1 subtypes. Expression of housekeeping genes are analyzed as controls for normalization. 
The relative abundance of proteins of each H1 subtype and core histones is obtained through reverse phase high-performance liquid chromatography (RP-HPLC) analysis of total histones extracted from mammalian cells11-13. The HPLC method and elution conditions described here give optimum separations of mouse H1 subtypes. By quantifying the HPLC profile, we calculate the relative proportion of individual H1 subtypes within H1 family, as well as determine the H1 to nucleosome ratio in the cells.

We describe a set of assays to analyze expression levels of H1 linker histones. mRNA of individual H1 genes are quantitatively measured by random primer based reverse transcription followed by real-time PCR, whereas protein quantification of H1 histones is achieved by HPLC analysis.

哺乳动物链接组蛋白亚型表达分析

Linker histone H1 binds to the nucleosome core particle and linker DNA, facilitating folding of chromatin into higher order structure.  H1 is essential ...

Visualization of Endoplasmic Reticulum Localized mRNAs in Mammalian Cells

In eukaryotes, most of the messenger RNAs (mRNAs) that encode secreted and membrane proteins are localized to the surface of the endoplasmic reticulum (ER). However, the visualization of these mRNAs can be challenging. This is especially true when only a fraction of the mRNA is ER-associated and their distribution to this organelle is obstructed by non-targeted (i.e. "free") transcripts. In order to monitor ER-associated mRNAs, we have developed a method in which cells are treated with a short exposure to a digitonin extraction solution that selectively permeabilizes the plasma membrane, and thus removes the cytoplasmic contents, while simultaneously maintaining the integrity of the ER. When this method is coupled with fluorescent in situ hybridization (FISH), one can clearly visualize ER-bound mRNAs by fluorescent microscopy. Using this protocol the degree of ER-association for either bulk poly(A) transcripts or specific mRNAs can be assessed and even quantified. In the process, one can use this assay to investigate the nature of mRNA-ER interactions.

Here we describe a method to visualize endoplasmic reticulum-associated mRNAs in mammalian tissue culture cells. This technique involves the selective permeabilization of the plasma membrane with digitonin to remove cytoplasmic contents followed by fluorescent in situ hybridization to detect either bulk poly(A) mRNA or specific transcripts.

在哺乳动物细胞中的内质网定位的mRNA的可视化

In eukaryotes, most of the messenger RNAs (mRNAs) that encode secreted and membrane proteins are localized to the surface of the endoplasmic reticulum ...

siRNA Screening to Identify Ubiquitin and Ubiquitin-like System Regulators of Biological Pathways in Cultured Mammalian Cells

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that regulates diverse biological pathways including the hypoxia response, proteostasis, the DNA damage response and transcription.&#160; To better understand how UBLs regulate pathways relevant to human disease, we have compiled a human siRNA &#8220;ubiquitome&#8221; library consisting of 1,186 siRNA duplex pools targeting all known and predicted components of UBL system pathways. This library can be screened against a range of cell lines expressing reporters of diverse biological pathways to determine which UBL components act as positive or negative regulators of the pathway in question.&#160; Here, we describe a protocol utilizing this library to identify ubiquitome-regulators of the HIF1A-mediated cellular response to hypoxia using a transcription-based luciferase reporter.&#160; An initial assay development stage is performed to establish suitable screening parameters of the cell line before performing the screen in three stages: primary, secondary and tertiary/deconvolution screening. &#160;The use of targeted over whole genome siRNA libraries is becoming increasingly popular as it offers the advantage of reporting only on members of the pathway with which the investigators are most interested.&#160; Despite inherent limitations of siRNA screening, in particular false-positives caused by siRNA off-target effects, the identification of genuine novel regulators of the pathways in question outweigh these shortcomings, which can be overcome by performing a series of carefully undertaken control experiments.

Here, we describe a methodology to perform a targeted siRNA &#8220;ubiquitome&#8221; screen to identify novel ubiquitin and ubiquitin-like regulators of the HIF1A-mediated cellular response to hypoxia.&#160; This can be adapted to any biological pathway where a robust read out of reporter activity is available.

siRNA的筛选识别泛素和泛素样系统压力表生物学途径在培养的哺乳动物细胞

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that ...