Characterization of noradrenaline-induced increases in intracellular Ca2+ levels in Chinese hamster ovary cells stably expressing human alpha1A-adrenoceptor

The mechanism for noradrenaline (NA)-induced increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) and physiological significance of Na(+) influx through receptor-operated channels (ROCs) and store-operated channels (SOCs) were studied in Chinese hamster ovary (CHO) cells stably expressing human alpha(1A)-adrenoceptor (alpha(1A)-AR). [Ca(2+)](i) was measured using the Ca(2+) indicator fura-2. NA (1 microM) elicited transient and subsequent sustained [Ca(2+)](i) increases, which were inhibited by YM-254890 (G(alphaq/11) inhibitor), U-73122 (phospholipase C (PLC) inhibitor), and bisindolylmaleimide I (protein kinase C (PKC) inhibitor), suggesting their dependence on G(alphaq/11)/PLC/PKC. Both phases were suppressed by extracellular Ca(2+) removal, SK&F 96365 (inhibitor of SOC and nonselective cation channel type-2 (NSCC-2)), LOE 908 (inhibitor of NSCC-1 and NSCC-2), and La(3+) (inhibitor of transient receptor potential canonical (TRPC) channel). Reduction of extracellular Na(+) and pretreatment with KB-R7943, a Na(+)/Ca(2+) exchanger (NCX) inhibitor, inhibited both phases of [Ca(2+)](i) increases. These results suggest that 1) stimulation of alpha(1A)-AR with NA elicits the transient and sustained increases in [Ca(2+)](i) mediated through NSCC-2 that belongs to a TRPC family; 2) Na(+) influx through these channels drives NCX in the reverse mode, causing Ca(2+) influx in exchange for Na(+) efflux; and 3) the G(alphaq/11)/PLC/PKC-dependent pathway plays an important role in the increases in [Ca(2+)](i).     

Characterization of organic anion transport inhibitors using cells stably expressing human organic anion transporters.

The organic anion transport system is involved in the tubular excretion of various clinically important drugs. The purpose of this study was to characterize the effects of various organic anion transport inhibitors on organic anion transport using proximal tubule cells stably expressing human organic anion transporter 1 (human-OAT1) and human-OAT3, which are localized to the basolateral membrane of the proximal tubule. Organic anion transport inhibitors including betamipron, cilastatin, KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine) and probenecid significantly inhibited human-OAT1- and human-OAT3-mediated organic anion uptake in a dose-dependent manner. Kinetic analyses revealed that these inhibitions were competitive. The Ki values of betamipron, cilastatin, KW-3902 and probencid for human-OAT1 were 23.6, 1470, 7.82 and 12.1 microM, whereas those for human-OAT3 were 48.3, 231, 3.70 and 9.0 microM. These results suggest that betamipron and probenecid could inhibit both human-OAT1- and human-OAT3-mediated organic anion transport in vivo, whereas cilastatin could inhibit only human-OAT3-mediated one. In contrast, KW-3902 did not exert the effects of significance, whereas KW-3902 was the most potent.     

药物高通量筛选的设计与实施

本文在简要介绍药物高通量筛选体系的基础上,就组建高效能的高通量筛选体系需要关注的因素,如作用靶点、测试方法、检测方法与作用靶点的匹配、关键参数、效能评价等进行了重点阐述,为高通量筛选体系的设计和实施提供了有益的借鉴。     

以微管蛋白为靶的高通量药物筛选方法的建立与应用

目的：以微管蛋白为靶建立高通量筛选（HTS）模型，以便有效地发现抗肿瘤化合物。方法：细胞培养与免疫荧光技术。结果：以常规的免疫组化（玻片）方法为基础优化实验条件，在96孔板上建立了以微管蛋白为靶点的高通量药物筛选模型；抗肿瘤药物紫杉醇和秋水仙碱作用于人肝癌HepG2细胞后，细胞的免疫荧光强度发生了明显的可检测的变化，间接反映药物对细胞徽管蛋白聚合／解聚作用的影响，与理论预测结果一致。结论：基于人肿瘤细胞的以徽管蛋白为靶点的高通量筛选方法可用于抗肿瘤化合物的筛选。     

炎性细胞因子抑制剂高通量筛选方法的研究

目的　建立能够同时作用于炎症相关细胞因子的药物筛选模型 ,探讨多指标综合筛选方法 ,为发现新的抗炎先导化合物提供快速有效的方法。方法　采用人血白细胞为研究对象 ,以脂多糖 (LPS)刺激诱发炎性因子生成 ,探讨最佳刺激条件 ,建立多指标检测方法和综合评价药物作用的分析方法。观察不同浓度脂多糖 (0 5～ 5 0mg·L-1)及不同作用时间 (0～ 4h)炎性因子IL 1、IL 8、TNF α生成水平的变化。同时观察 5 LO抑制剂NDGA (nordihydroguaiareticacid)和COX 2抑制剂Diclofenac在多种细胞因子筛选模型上的应用。结果　脂多糖可浓度依赖性 (0 5～ 5 0mg·L-1)和时间依赖性 (0～ 4h)地刺激人血白细胞释放IL 1、IL 8和TNF α。脂多糖 (终浓度 5mg·L-1)刺激人血白细胞 4h有较高释放 ,与对照组比差异明显。NDGA和Diclofenac在脂多糖刺激 4h对炎性因子释放有显著抑制作用。结论　这种脂多糖体外刺激人血白细胞释放多种炎性因子的筛选模型可用于高通量大规模筛选具有抗炎作用的先导化合物 ,提高了筛选效率     

人源HepaRG肝细胞毒性与遗传毒性高通量筛选方法的初步建立

目的 利用正常人源肝细胞（HepaRG）和高内涵技术检测肝毒性标志物,并结合微核试验和单细胞凝胶电泳试验建立体外细胞毒性和遗传毒性的快速筛选平台。方法 选取适当的荧光探针Hoechst33342、DCFH-DA、Fluo4-AM、MitoTracker^® Red CMX Ros联合高内涵技术研究不同大黄蒽醌类单体（AQs）对HepaRG细胞活性氧簇（ROS）、胞内Ca²⁺含量及线粒体膜完整性等肝毒性标志物的影响,并开展高内涵法胞质分裂阻断法微核试验和高通量彗星电泳试验,综合评价AQs致肝细胞毒性及染色体、DNA损伤情况。结果 与对照组比较,HepaRG细胞经25.0 μg/mL大黄素、12.5和25.0 μg/mL芦荟大黄素、50和25.0 μg/mL大黄酚处理24 h后,胞内ROS含量显著增多;12.5和25.0 μg/mL芦荟大黄素和50.0 μg/mL大黄酸可引起胞内Ca²⁺含量显著增多;大黄素25.0 μg/mL、芦荟大黄素25.0 μg/mL、大黄酚50.0和25.0 μg/mL、大黄酸50.0和25.0 μg/mL组导致线粒体明显损伤（P<0.05、0.01）。与对照组比较,25.0 μg/mL大黄素诱导微核率、尾DNA含量和彗星尾距（OTM）数值均显著升高（P<0.05、0.01）;50.0 μg/mL大黄酚给药72 h后微核率显著升高（P<0.01）。结论 AQs的研究结果与现有文献报道基本相符。本研究成功建立肝细胞毒性和遗传毒性的联合快速筛选模型,有助于药物研发早期的毒性筛选。     

Fibrinogen interaction of CHO cells expressing chimeric αⅡb/αvβ3 integrin

AIM: The molecular mechanisms of the affinity regulation of alphavbeta3 integrin are important in tumor development, wound repairing, and angiogenesis. It has been established that the cytoplasmic domains of alphavbeta3 integrin play an important role in integrin-ligand affinity regulation. However, the relationship of structure-function within these domains remains unclear. METHODS: The extracellular and transmembrane domain of alphaIIb was fused to the alphav integrin cytoplasmic domain, and the chimeric alpha subunit was coexpressed in Chinese hamster ovary (CHO) cells with the wild-type beta3 subunit or with 3 mutant beta3 sequences bearing truncations at the positions of T741, Y747, and F754, respectively. The CHO cells expressing these recombinant integrins were tested for soluble fibrinogen binding and the cell adhesion and spreading on immobilized fibrinogen. RESULTS: All 4 types of integrins bound soluble fibrinogen in the absence of agonist stimulation, and only the cells expressing the chimeric alpha subunit with the wild-type beta3 subunit, but not those with truncated beta3, could adhere to and spread on immobilized fibrinogen. CONCLUSION: The substitution alphaIIb at the cytoplasmic domain with the alphav cytoplasmic sequence rendered the extracellular alphaIIbbeta3 a constitutively activated conformation for ligands without the need of pinside-outq signals. Our results also indicated that the COOH-terminal sequence of beta3 might play a key role in integrin alphaIIb/alphavbeta3-mediated cell adhesion and spreading on immobilized fibrinogen. The cells expressing alphaIIb/alphavbeta3 have enormous potential for facilitating drug screening for antagonists either to alphavbeta3 intracellular interactions or to alphaIIbbeta3 receptor functions.     

Characterization of a trypsin-dependent avian influenza H5N1-pseudotyped HIV vector system for high throughput screening of inhibitory molecules

In this study, we have generated and characterized an avian influenza H5N1 hemagglutinin (HA), neuraminidase (NA) and M2 ion channel pseudotyped HIV-based vector system (HaNaM-pseudotyped HIV vector). The cleavage site of the HA protein was modified to necessitate trypsin-dependent maturation of the glycoprotein. HA, NA and M2 were efficiently incorporated in HIV vector particles which could transduce different cell lines in a trypsin-dependent manner. Results also showed that the presence of avian influenza M2 and NA proteins maximized both vector production and transduction and that transduction was highly sensitive to the specific NA inhibitor oseltamivir (Tamiflu). H5N1 HaNaM-pseudotyped HIV vector system was also adapted for cell-based high throughput screening of drug candidates against influenza virus infection, and its high sensitivity to the specific oseltamivir validates its potential utility in the identification of new influenza inhibitors. Overall, the trypsin-dependent H5N1-pseudotyped HIV vector can mimic avian influenza virus infection processes with sufficient precision to allow for the identification of new antivirals and to study avian influenza virus biology in a lower biosafety level laboratory environment.     

Stable expression and characterisation of a human alpha 7 nicotinic subunit chimera: a tool for functional high-throughput screening

A chimera comprising the N-terminal region of the human alpha7 nicotinic acetylcholine receptor, fused to the transmembrane/C-terminal domains of the mouse serotonin 5-HT3 receptor, was constructed. Injection of the chimera cDNA into Xenopus oocytes, or transient transfection in human embryonic kidney (HEK-293) cells, resulted in the expression of functional channels that were sensitive to nicotinic acetylcholine, but not serotonin receptor ligands. In both systems, the responses obtained from chimeric receptors inactivated more slowly than those recorded following activation of wild-type alpha7 receptors. A stable HEK-293 cell line expressing the human alpha7/mouse 5-HT3 chimera was established, which showed that the chimera displayed a similar pharmacological profile to wild-type alpha7 receptors. Use of this chimera in high-throughput screening may enable the identification of novel pharmacological agents that will help to define further the role of alpha7 nicotinic receptors in physiology and disease.     

Development of novel IC-ELISA as a primary high throughput screening for various estrogen molecules

An indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) has been developed for detecting estrogen molecules in environmental samples. For generating anti-estrogen monoclonal antibody (mAb), BALB/c mice were immunized with 17-estra-diol (E2)-BSA and 5760 hybridoma cell lines were established. Through the optimization processes, a mAb(4BSA-e 3C11) and estriol(E3)-BSA were finally selected as a primary antibody and a coating antigen, respectively. The IC₅₀ value for a standard estrogen (17β-E2) was 6.26 ng mL^? and the detection range (20–80% B/B₀) was 0.01–377.92ng mL^?. The developed IC-ELISA showed some cross-reactivities (CRs) to various estrogen analogues, such as estrone (E1) (1.79%), E3(77.34%), 16-epiestriol(27.54%) and 16 keto-17β-E2(2.02%). On the other hand, the assay showed a negligible CRs to other steroid hormones (CR5<0.063%), suggesting the specificity of the assay to estrogen molecules. For assay validation, the developed IC-ELISA was compared side by side with high performance liquid chromatography (HPLC), which showed no significant difference in their performances between the two methods. The sensitivity of our IC-ELISA was approximately 100 fold higher than that of HPLC. The estrogen contents (Estrogen Equivalent Concentrations; EEC) in field samples were determined using the IC-ELISA, including swine sewage effluents (7.043 ± 0.023 ng-EEC mL^?1), bovine feces (0.013±0.001 ng-EEC mL^?1), and avian feces (0.017±0.001 ng-EEC mL^?). Conclusively, we have developed an IC-ELISA that is highly sensitive to estrogens as well as can detect various estrogen analogues at the same time. This assay can be used as a primary screening for a large number of field samples before the instrumental analysis that is laborintensive and time-consuming.     

Characterization of diversity in toxicity mechanism using in vitro cytotoxicity assays in quantitative high throughput screening

Assessing the potential health risks of environmental chemical compounds is an expensive undertaking that has motivated the development of new alternatives to traditional in vivo toxicological testing. One approach is to stage the evaluation, beginning with less expensive and higher throughput in vitro testing before progressing to more definitive trials. In vitro testing can be used to generate a hypothesis about a compound's mechanism of action, which can then be used to design an appropriate in vivo experiment. Here we begin to address the question of how to design such a battery of in vitro cell-based assays by combining data from two different types of assays, cell viability and caspase activation, with the aim of elucidating the mechanism of action. Because caspase activation is a transient event during apoptosis, it is not possible to design a single end-point assay protocol that would identify all instances of compound-induced caspase activation. Nevertheless, useful information about compound mechanism of action can be obtained from these assays in combination with cell viability data. Unsupervised clustering in combination with Dunn's cluster validity index is a robust method for identifying mechanisms of action without requiring any a priori knowledge about mechanisms of toxicity. The performance of this clustering method is evaluated by comparing the clustering results against literature annotations of compound mechanisms.     

RNR2调控的重组绿色荧光蛋白酵母细胞的构建及其对化学诱变原的高通量筛选

目的建立RNR2调控的酵母增强绿色荧光蛋白(yEGFP)发光酵母细胞,高通量筛选化学诱变原。方法用PCR方法从酵母(W303-1A)基因组扩增RNR2启动子,经酶切后,用T4连接酶与线性化的含酵母嗜好遗传密码子的yEGFP报告载体相连,连接产物转化子质粒经酶切和测序鉴定,构建RNR2调控的yEGFP酵母报告载体。用醋酸锂方法将其转化于W303-1A酵母细胞,从而构建成RNR2调控的yEGFP发光酵母细胞(W303-1A/RNR2-yEGFP)。用甲磺酸甲酯0～400mg·L-1分别作用于该发光酵母细胞0,4,8,12,16和20h后,于倒置荧光显微镜下观察荧光,用多功能酶标仪检测其荧光发光强度,选择最佳诱导时间;用不同浓度的DNA烷化剂、DNA断裂剂和DNA合成酶抑制剂作用于该重组细胞16h,检测其荧光发光强度,考察W303-1A/RNR2-yEGFP细胞对各种化学诱变原的敏感性。结果经测序确定W303-1A/RNR2-yEGFP构建成功。选择16h为最佳诱导时间;各种化学诱变原与W303-1A/RNR2-yEGFP细胞作用16h后,与DNA发生结合的化合物中放线菌素D和溴乙锭诱导的发光度与对照组无明显差别,发光倍数<1.5;与DNA发生烷基化的化合物中,甲磺酸甲脂200mg·L-1诱导的细胞发光度最强,发光倍数为5.21,瘤可宁200μg·L-1诱导的发光倍数为1.9,而丝裂霉素C的发光度与对照组无明显差别。在使DNA发生断裂的诱变原中,顺铂250mg·L-1诱导的细胞最高发光倍数为3.7,其次4-硝基-N-氧化喹啉3.1mg·L-1、博来霉素12.5mg·L-1和福来霉素200mg·L-1,最高诱导倍数分别为2.35,2.26和2.53;在抑制DNA合成酶或拓扑异构酶的诱变原中,5-氟尿嘧啶500μg·L-1、羟基脲570.45mg·L-1和喜树碱30mg·L-1所诱导的细胞最大发光倍数分别为2.36,2.65和2.53;而非基因毒性化合物秋水仙碱、刀豆氨酸和四环素诱导的发光度与对照无明显差别。结论该重组发光酵母细胞可用于对多数造成DNA断裂或合成阻断的化学诱变原筛选,具有快速、方便和高通量等特点。     

中药活性成分的高通量筛选新技术

以近年来国内外研究文献为基础,总结概括了近5年来中药活性成分的高通量筛选新技术的进展情况。其中生物色谱技术、芯片技术和计算机辅助虚拟筛选等技术得到了广泛应用。这些新技术在中药活性成分筛选方面,比起传统方法具有效率高、自动化、通量高的优点,可以为中药活性成分的高通量筛选提供新思路。     

Functional characterisation of human glycine receptors in a fluorescence-based high throughput screening assay

The human glycine receptor subtypes alpha1beta and alpha2 have been expressed stably in HEK293 cells, and the functional characteristics of the receptors have been characterised in the FLIPR Membrane Potential Assay. The pharmacological properties obtained for nine standard ligands at the two receptors in this assay were found to be in good agreement with those from electrophysiology studies of the receptors expressed in Xenopus oocytes or mammalian cell lines. Hence, this high throughput screening assay will be of great use in future pharmacological studies of glycine receptors, particular in the search for novel compound structures acting at them.     

Development of a homogeneous calcium mobilization assay for high throughput screening of mas-related gene receptor agonists

AIM: To develop homogeneous calcium mobilization assay for high-throughput screening (HTS) of mas-related gene (Mrg) receptor agonists. METHODS: CHO-K1 cells stably expressing the full-length MrgD receptor and a calcium-sensitive dye were used to develop an HTS assay based on intracellular calcium influx. This method was applied to large-scale screening of a library containing 8000 synthetic compounds and natural product extracts. cAMP measurements were carried out to verify the bioactivities of the hits found by the calcium mobilization assay. Similar approaches were also employed in the identification of the MrgA1 receptor agonists following HTS of 16,000 samples. RESULTS: EC(50) values of the positive control compounds (beta-alanine for MrgD receptor and dynorphin A for MrgA1 receptor) determined by the calcium mobilization assay were consistent with those reported in the literature, and the Z' factors were 0.65 and 0.50 for MrgD and MrgA1 receptor assay, respectively. About 31 compounds for the MrgD receptor and 48 compounds for the MrgA1 receptor showing > or =20% of the maximal agonist activities found in the controls were initially identified as hits. Secondary screening confirmed that 2 compounds for each receptor possessed specific agonist activities. Intracellular cAMP level measurements indicated that the 2 confirmed hits displayed the functionality of the MrgD receptor agonists. CONCLUSION: A series of validation studies demonstrated that the homogeneous calcium mobilization assay developed was highly efficient, amenable to automation and a robust tool to screen potential MrgD and MrgA1 receptor agonists. Its application may be expanded to other G-protein coupled receptors that mobilize calcium influx upon activation.     

Applications of fluorescent polymer superquenching to high throughput screening assays for protein kinases

Protein kinases are involved in the regulation of cellular metabolism, growth, differentiation, and proliferation. Aberrations in their function can lead to diseases such as cancer and inflammation. Protein kinases are therefore possible targets for drug therapies. To address the need for high throughput screening of potential inhibitors, QTL has developed a homogeneous and robust kinase assay for use in multiwell plate format. The QTL Lightspeed fluorescence superquenching-based kinase assays do not require specialized equipment, nor do they involve the use of radioactive hazardous materials or antibodies. QTL Lightspeed kinase assays directly measure the enzymatic activity of the target and do not involve secondary (detector) enzyme. In this article, we compare QTL Lightspeed protein kinase assays using Protein Kinase A, Protein Kinase Balpha/Akt1, and ribosomal S6 kinase-2 as examples with other commercially available kinase kits. Our data show that QTL Lightspeed kinase assays offer significant advantages over the current commercial kits in terms of both sensitivity and performance. The QTL Lightspeed kinase assay also offers a kinetic assay mode where the substrate phosphorylation can be monitored in real-time.     

5-羟色胺1A受体激动剂高通量筛选模型的建立

目的为发现5-羟色胺1A(5-HT1A)受体的激动剂,通过报告基因活性检测的方法建立高通量筛选(HTS)细胞模型。方法将带有人源5-HT1A受体的真核表达质粒pcD-NA3.1(pcDNA3.1-h5-HT1AR)与带有报告基因pCRE-luc的pcDNA3.1质粒(pcDNA3.1-pCRE-luc)共转染到工具细胞中,通过对工具细胞选择、共转染质粒比例、化合物孵育时间及阳性化合物选择等条件进行探索和优化,建立了稳定表达人源5-HT1A受体并可用于该受体激动剂筛选的细胞模型(HEK293-h5-HT1AR)。结果①根据瞬转实验中信号值的高低,模型采用HEK293细胞作为工具细胞;②根据瞬转实验中的信噪比,发现pcDNA3.1-h5-HT1AR:pcDNA3.1-pCRE-luc的最佳比例为1∶3;③对化合物孵育时间进行优化,选择的最佳孵育时间为6 h;④阳性化合物的选择过程中,实验研究了5-HT.HCl,Flibanserin,8-OH-DPAT以及Lorcaser-in(APD356)4个已报道有5-HT1A受体激动活性的化合物,结果表明APD356在该体系中最适合作为阳性对照化合物。⑤该细胞株连续培养12代,信号稳定。结论通过对一系列实验条件进行选择和优化,建立了一个稳定表达人源5-HT1A受体的细胞模型,该模型可用于高通量5-HT1A激动剂的筛选。