人高密度脂蛋白受体CLA-1表达上调剂4776B和4776C的分离、结构鉴定及生物活性研究

目的 从微生物代谢产物中筛选和分离能够上调人高密度脂蛋白受体（CLA-1）表达的新型活性化合物。方法 应用本实验室已经建立的CLA-1表达上调剂的高通量筛选模型，从6000多株微生物中筛选出8株能使CLA-1表达上调的阳性菌株。对其中一株阳性菌株放线菌04-4776发酵产物的活性成分进行活性跟踪分离纯化，从中获得CLA-1表达上调的化合物4776B和4776C，并测定了化合物的理化特性和波谱学数据及相关的生物活性。结果通过理化性质、质谱、紫外和核磁等波谱学数据的分析，确定了化合物4776B和4776C的结构；4776B和4776C对CLA-1的上调率分别在2．08和3．26μmol／L时达到最大，与对照相比分别上调了60％和78％。结论 放线菌04-4776产生的两个活性化合物分别与文献报道的红车轴草素和（9R，13S）-7-脱氧-13-二氢道诺霉素酮结构一致；两个化合物均具有强的上调CLA-1的表达活性，属首次报道。     

人高密度脂蛋白受体CLA-1上调剂9179D的分离、结构鉴定和活性研究

目的从微生物代谢产物中分离能够上调人高密度脂蛋白受体（CLA-1）表达的新型活性化合物,并对其活性进行研究。方法应用已建立的CLA-1表达上调剂的模型,对阳性菌株链霉菌104A-9179发酵产物的活性成分进行分离纯化,获得活性化合物9179D;通过理化性质、质谱、紫外和核磁等波谱学数据进行结构鉴定;利用RT-PCR和Western Blot方法检测9179D对HepG2中CLA-1表达的影响;利用流式细胞仪检测其对小鼠巨噬细胞RAW264.7结合DiI-HDL的影响。结果从链霉菌104A-9179发酵产物中得到活性化合物9179D,并确定了其结构为曲占柳菌素D（Trichostatin D）;9179D在CLA-1上调剂模型上的EC₅₀为46.02μmol/L,表达活性最高值为934%;9179D能增加HepG2中CLA-1的mRNA和蛋白表达;增加RAW264.7对DiI-HDL的结合。结论得到一个微生物来源的具有强的上调CLA-1的表达活性的化合物-9179D（曲古柳菌素D）,属首次报道。     

ABCA1：动脉粥样硬化治疗的新方向

动脉粥样硬化是导致心血管疾病的主要原因，血浆中的HDL水平与AS呈现高度负相关性。ABCA1是ATP-结合盒转运蛋白超家族中的一员，能介导转运胆固醇至细胞膜与载脂蛋白结合形成HDL，从而从外周细胞转运胆固醇至肝脏，再从胆汁分泌中清除，防止胆固醇在巨噬细胞中沉积，防止AS的发生。有ABCA1基因突变引起的tangier病纯合子发生AS的几率几乎比正常人高6倍。由此可见，ABCA1在胆固醇转运，HDL代谢和防动脉粥样硬化中都起到一定作用。     

ABCA1基因单核苷酸多态性的临床意义

ATP结合的盒转运子A1(ATP Banding cassette Transporter al，ABCA1)促进细胞内游离胆固醇和磷脂的流出，在胆固醇逆转运(RCT)和HDL生成的起始步骤起重要作用；同时ABCA1与动脉粥样硬化(AS)和冠心病的发生密切相关。ABCA1基因的单核苷酸多态性(SNP)广泛存在于普通人群及冠心病人群中，不同人种、不同SNP位点对ABCA1功能影响不同，同一SNP在不同人种其作用也不同，ABCAISNP与血浆HDL—C水平、炎症细胞因子及冠心病发生密切相关。因此，ABCAISNP可能是影响血浆HDL—C水平及冠心病发生的重要因素。     

基于极化荧光方法的人LOX-1配体高通量筛选

目的建立以极化荧光为检测方法的高通量筛选技术，通过大规模筛选发现氧化型低密度脂蛋白受体-1(LOX-1)的天然配体。方法密度梯度超速离心获得正常人血中低密度脂蛋白(LDL)，然后用CuSO₄(5 μmol·L^-1)修饰为氧化型低密度脂蛋白(oxLDL)。FITC标记hLOX-1，以受体(LOX-1)和配体(oxLDL)的相互作用为基础建立筛选模型，用极化荧光检测方法，在激发光485 nm、发射光525 nm,对3 200个样品进行高通量筛选，并用Z′因子值评价实验。结果Z′因子值为0.75，根据建立的基于极化荧光的高通量筛选实验方法，发现3个化合物与hLOX-1有较高的结合活性，IC₅₀值小于31.6 μmol·L^-1。结论极化荧光检测方法适合于高通量筛选技术，具有较高的稳定性、灵敏性和可重复性。     

苯扎贝特对THP1巨噬细胞PPARγ及ABCA1表达的影响

目的 探讨苯扎贝特对THP1巨噬细胞PPARγ及ABCA1表达的影响.方法 THP1细胞经PMA诱导24h后,添加不同浓度苯扎贝特(0、1、10、50μmol/L)继续作用24h,RT-PCR法测定PPARγ、ABCA1 mRNA表达.结果 PMA刺激THP1细胞表达PPARγ及ABCA1;苯扎贝特剂量依赖性上调THP-1巨噬细胞PPARγ及ABCA1的表达(P＜0.05),50μmol/L浓度时二者表达最高,且PPARγ与ABCA1的mRNA表达呈正相关(r=0.628,P=0.002).结论 苯扎贝特上调THP1细胞中PPARγ和ABCA1的表达.     

人源蛋白酪氨酸磷酸酶(PTP1B)抑制剂的高通量筛选

本研究拟建立体外人源蛋白酪氨酸磷酸酶(PTP1B)抑制剂高通量筛选模型,用于PTP1B抑制剂的发现。利用大肠杆菌重组表达PTP1B,以对硝基苯磷酸二钠(PNPP)为特异性的底物,建立了基于酶反应速率的384孔微板为载体的PTP1B抑制剂高通量筛选模型(Z'=0.78)。选择24 240个样品进行筛选,对抑制率大于70%的80个样品作为活性样品进行复筛,最终确定6个具有较强的抑制活性的化合物J5753、J10550、J10551、J10583、J10585和J11101,其IC50值分别为21.58、18.39、15.37、11.92、37.27和36.61μg·mL-1。结果表明,所建立的PTP1B抑制剂高通量筛选模型具有快速、灵敏、稳定、重复性好的特点。     

普伐他汀治疗过程中ABCA1基因变异对心脏病患者的影响

目的 研究普伐他汀治疗过程中ABCA1基因变异对心脏病患者的影响。方法 选取236例冠心病(coronary heart disease,CHD)患者与267例健康体检者(设为对照组)。CHD患者分为常规治疗组和普伐他汀组,常规治疗组口服阿司匹林0.1 g·d^-1,普伐他汀组在口服阿司匹林0.1 g·d^-1的基础上给予普伐他汀35 mg·d^-1,抽血检测患者治疗前、治疗8、16周后的总胆固醇(total cholesterol,TC)、高密度脂蛋白胆固醇(high-density lipoprotein cholesterol,HDL-C)、载脂蛋白A-I(apoprotein A-I,apoA-I)、低密度脂蛋白胆固醇(low-density lipoprotein cholesterol,LDL-C)、载脂蛋白B(apoprotein B,apoB)和三酰甘油(triacylglycerol,TG)水平,提取DNA进行基因型分析。对照组抽血检测6项生化指标,采用Taqman探针技术提取DNA并进行基因型分析。结果 CHD患者吸烟者139例显著高于对照组116例;ABCA1 R219K基因变异频率两者相似,K携带者所占比率：CHD组为67.8%,对照组为66.7%;普伐他汀组治疗8,16周后较常规治疗组的TC、TG、LDL-C、apoB水平低,HDL-C、apoA-I水平高,差异具有统计学意义(P<0.05);CHD患者中K携带者HDL-C、apoA-I水平高于RR型,TG水平低于RR型,普伐他汀治疗前后LDL-C、apoB、TC水平在RR、RK、KK 3种基因型组间差异无统计学意义;治疗前后K携带患者的HDL-C以及apoA-I水平显著高于RR基因型患者(P<0.05);ABCA1基因变异对普伐他汀治疗疗效有促进作用,尤其KK基因型与RR型相比,具极显著促进作用(P=0.008)。结论 ABCA1基因变异影响冠心病患者血浆脂质水平,尤其是HDL-C和apoA-I的水平。     

聚腺苷二磷酸核糖聚合酶-1抑制剂高通量筛选模型

目的建立体外聚腺苷二磷酸核糖聚合酶-1[Poly(ADP-ribose)polymerase-1,PARP-1]抑制剂的高通量筛选模型,筛选潜在的PARP-1抑制剂。方法将PARP-1、裸DNA与底物NAD+反应,再将剩余底物NAD+转化为荧光物质,通过测定其荧光强度来决定PARP-1的活性,并以此筛选PARP-1的抑制剂。建立384孔板的高通量筛选模型,对9280个化合物(包括合成化合物、天然产物、微生物发酵提取物)组成的随机库进行体外筛选。结果筛选出148个活性化合物对PARP-1的抑制作用大于70%,最终确定3个化合物具有较高的抑制活性。结论建立的PARP-1抑制剂高通量筛选模型具有灵敏度高、快速、微量、准确的特点。     

人一型胶原酶抑制剂的高通量筛选

AIM: To establish a high-throughput method for inhibitor screening using a recombinant collagenase catalytic domain. METHODS: Human collagenase 1 catalytic domain protein was expressed in E coli and used for screening a set of 2720 compounds in a high-throughput fashion. RESULTS: The screening was accomplished within 2 h and 10 min with consumption of each compound at 4 micrograms. Sixty-six compounds were identified with > 60% inhibitory activity at 20 mg/L, among which 44 compounds were confirmed by subsequent testing at multiple concentrations. The most potent compound showed an IC50 at 4.3 mumol/L, and there were total 15 compounds with IC50 less than 20 mumol/L. CONCLUSION: The high-throughput method using the recombinant collagenase is fast, effective and practical in identifying inhibitors.     

A functional steroid-binding element in an ATP-binding cassette multidrug transporter

The human breast cancer resistance protein is an ATP-binding cassette (ABC) multidrug transporter that affects the bioavailability of chemotherapeutic drugs and can confer drug resistance on cancer cells. It is the second member of the ABCG subfamily, other members of which are associated with human steroid disorders such as hypercholesterolemia, sitosterolemia, and atherosclerosis. The molecular bases of protein-steroid interactions in ABC transporters are unknown. Here, we identify a steroid-binding element in the membrane domain of ABCG2 with a similarity to steroid hormone/nuclear receptors. The element facilitates steroid hormone binding and mediates modulation of ABCG2 activity. The identification of this element might provide an opportunity for the development of new therapeutic ligands for ABCG2.     

New structure model for the ATP-binding cassette multidrug transporter LmrA

Multidrug resistance of pathogenic microorganisms and mammalian tumors can be associated with the overexpression of multidrug transporters. These integral membrane proteins are capable of extruding a wide range of structurally unrelated compounds from the cell. Among the different classes of multidrug transporters are the ATP binding cassette (ABC) transporters, which are dependent on the binding and hydrolysis of ATP. In the past five years, many researchers have built homology models of ABC extrusion systems using the atomic coordinates of crystallized MsbA, a lipopolysaccharide transporter in Gram-negative bacteria. Likewise, we have previously used the Vibrio cholera MsbA structure as a template in the modeling of the multidrug transporter LmrA from Lactococcus lactis. In view of the recently discovered inaccuracies in the MsbA structure, we have remodelled LmrA using the atomic coordinates of the MsbA homologue Sav1866 from Staphylococcus aureus. To compare and test our MsbA-based and Sav1866-based LmrA models we performed cysteine cross-linking at three key positions in LmrA. The pattern of cross-linking at these positions was consistent with the overall topology of transmembrane helices in Sav1866, suggesting that its crystal structure might be physiologically relevant. We recently identified E314 as a residue important in proton conduction by LmrA. The predicted location of this residue at the interface between the two half-transporters in the Sav1866-based homodimer, within the inner leaflet of the phospholipid bilayer, provides a new structural basis for the role of E314 in LmrA-mediated transport.     

The effect of T0901317 on ATP-binding cassette transporter A1 and Niemann-Pick type C1 in apoE-/- mice

Although a range of studies indicated Liver X receptor (LXR) activation inhibited the development of atherosclerosis in animal models, the mechanism of this effect for LXR agonists has not been fully understood. A recent study has suggested LXR activators increased the amount of free cholesterol in the plasma membrane of human macrophages by inducing Niemann-Pick type C1 (NPC1) gene expression. Therefore, we hypothesize that LXRs may also promote NPC1 expression in vivo. Here we investigated the effect of a synthetic LXR agonist T0901317 on ATP-binding cassette transporter A1 (ABCA1) and NPC1 in apolipoprotein E knockout (apoE-/-) mice. Male apoE-/- mice were randomized into four groups: baseline group (n = 10), vehicle group (n = 14), prevention group (n = 14), and treatment group (n = 14). En face analysis and Oil red O staining were used to examine the aortic atherosclerotic lesions. Macrophage content of aortic root atherosclerotic lesions and cholesterol efflux form peritoneal macrophages were measured. Gene and protein expression was analyzed by real-time quantitative polymerase chain reaction and Western blotting, respectively. T0901317 treatment reduced aortic atherosclerotic lesion area by 64.2% in prevention group (P < 0.001) and 58.3% in treatment group (P < 0.001) and resulted in a reduction in macrophage content. Plasma triglyceride, total cholesterol, high-density lipoprotein cholesterol, and apoA-I concentrations were markedly increased in T0901317-treated groups. T0901317 also promoted ABCA1 and NPC1 gene and protein levels in the aorta, liver, and small intestine of apoE-/- mice and significantly increased cholesterol efflux from peritoneal macrophages. T0901317 upregulates ABCA1 and NPC1. This study gives us a new insight into the mechanism for antiatherogenic effect of LXR synthetic agonists.     

ABC家族转运体与糖尿病

糖尿病是一种常见的全身性慢性代谢疾病,其发病过程伴随着血糖、血脂和激素水平的失调,并由此引发高血脂、动脉粥样硬化、心肌病等并发症.ABCA,ABCB,ABCC,ABCG等ABC家族转运体有可能参与糖尿病及其并发症发病机制.如ABCA1和ABCG1促使细胞内的胆固醇泵出,进入高密度脂蛋白通路,减少巨噬细胞中的胆固醇沉积,防止巨噬细胞转化为泡沫细胞;ABCG5和ABCG8抑制肠道膳食中脂类吸收,并促进胆固醇通过胆汁排泄;表达在胰岛β细胞上的ABCC8作为钾通道的调节亚基控制胰岛素的释放,维持血糖平衡;ABCB1,ABCC1-ABCC5以及ABCC2是药物转运相关的外排蛋白,影响着其底物药物的体内过程,也参与体内内源性物质的转运.上述ABC家族转运体缺失或变异有可能诱发糖尿病及其并发症;而糖尿病状态下体内环境的变化也会改变这些ABC家族转运体表达与功能,进一步加剧了病情的发展.本文讨论了糖尿病及与之相关的四类ABC家族转运体,以期深入理解两者之间的相互作用,为糖尿病研究和治疗提供新思路.     

Metabolism of ATP-binding cassette drug transporter inhibitors: complicating factor for multidrug resistance

Membrane transport proteins belonging to the ATP-binding cassette (ABC) family of transport proteins play a central role in the defence of organisms against toxic compounds, including anticancer drugs. However, for compounds that are designed to display a toxic effect, this defence system diminishes their effectiveness. This is typically the case in the development of cellular resistance to anticancer drugs. Inhibitors of these transporters are thus potentially useful tools to reverse this transporter-mediated cellular resistance to anticancer drugs and, eventually, to enhance the effectiveness of the treatment of patients with drug-resistant cancer. This review highlights the various types of inhibitors of several multidrug resistance-related ABC proteins, and demonstrates that the metabolism of inhibitors, as illustrated by recent data obtained for various natural compound inhibitors, may have considerable implications for their effect on drug transport and their potential for treatment of drug resistance.     

Variations in ATP-binding cassette transporter regulation during the progression of human nonalcoholic fatty liver disease

Transporters located on the sinusoidal and canalicular membranes of hepatocytes regulate the efflux of drugs and metabolites into blood and bile, respectively. Changes in the expression or function of these transporters during liver disease may lead to a greater risk of adverse drug reactions. Nonalcoholic fatty liver disease (NAFLD) is a progressive condition encompassing the relatively benign steatosis and the more severe, inflammatory state of nonalcoholic steatohepatitis (NASH). Here, we present an analysis of the effect of NAFLD progression on the major ATP-binding cassette (ABC) efflux transport proteins ABCC1-6, ABCB1, and ABCG2. Human liver samples diagnosed as normal, steatotic, NASH (fatty), and NASH (not fatty) were analyzed. Increasing trends in mRNA expression of ABCC1, ABCC4-5, ABCB1, and ABCG2 were found with NAFLD progression, whereas protein levels of all transporters exhibited increasing trends with disease progression. Immunohistochemical staining of ABCC3, ABCB1, and ABCG2 revealed no alterations in cellular localization during NAFLD progression. ABCC2 staining revealed an alternative mechanism of regulation in NASH in which the transporter appears to be internalized away from the canalicular membrane. This correlated with a preferential shift in the molecular mass of ABCC2 from 200 to 180 kDa in NASH, which has been shown to be associated with a loss of glycosylation and internalization of the protein. These data demonstrate increased expression of multiple efflux transporters as well as altered cellular localization of ABCC2 in NASH, which may have profound effects on the ability of patients with NASH to eliminate drugs in an appropriate manner.     

ATP结合盒蛋白E1在真核生物中的作用

ATP结合盒（ATP-binding cassette,ABC）蛋白超家族是真核生物进化过程中最为保守的一类蛋白。ABCE1是ABC超家族中E亚家族的唯一成员,除可抑制哺乳动物核糖核酸酶L外,还参与真核生物蛋白合成的翻译起始、终止及核糖体循环,并有可能成为新的抗肿瘤靶点。本文对ABCE1的基本生物学特性及其生物学作用作一介绍。     

Prediction and identification of drug interactions with the human ATP-binding cassette transporter multidrug-resistance associated protein 2 (MRP2; ABCC2)

The chemical space of registered oral drugs was explored for inhibitors of the human multidrug-resistance associated protein 2 (MRP2; ABCC2), using a data set of 191 structurally diverse drugs and drug-like compounds. The data set included a new reference set of 75 compounds, for studies of hepatic drug interactions with transport proteins, CYP enzymes, and compounds associated with liver toxicity. The inhibition of MRP2-mediated transport of estradiol-17beta-D-glucuronide was studied in inverted membrane vesicles from Sf9 cells overexpressing human MRP2. A total of 27 previously unknown MRP2 inhibitors were identified, and the results indicate an overlapping but narrower inhibitor space for MRP2 compared with the two other major ABC efflux transporters P-gp (ABCB1) and BCRP (ABCG2). In addition, 13 compounds were shown to stimulate the transport of estradiol-17beta-D-glucuronide. The experimental results were used to develop a computational model able to discriminate inhibitors from noninhibitors according to their molecular structure, resulting in a predictive power of 86% for the training set and 72% for the test set. The inhibitors were in general larger and more lipophilic and presented a higher aromaticity than the noninhibitors. The developed computational model is applicable in an early stage of the drug discovery process and is proposed as a tool for prediction of MRP2-mediated hepatic drug interactions and toxicity.