Analysis of molecular basis for the presence of interindividual difference in the biliary excretion of xenobiotics

异生物质胆汁排泄存在个体差异的分子基础分析

基本信息

批准号：
09470523
负责人：
SUZUKI Hiroshi
金额：
$ 3.97万
依托单位：
Graduate School of Pharmaceutical Sciences, The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Liver, along with kidney, plays an important role in the detoxification of xenobiotics. In the present study, we have performed the cDNA cloning of canalicular multispecific organic anion transporter (cMOAT) and examined its function by using the membrane vesicles isolated from NIH3T3 cells transfected with this cDNA.By examining the transport properties of organic anions with isolated bile canalicular membrane vesicles (CMVs), we have also suggested the presence of multiplicity for the transporters located on the bile canalicular membrane. In addition, cDNA cloning of cMOAT family members was performed. With RT-PCR, we could amplify cDNA fragments of MRP3 and 6 from the liver of Eisai hyperbilirubinemic rats whose cMOAT function is hereditarily defective. We also succeeded in the cDNA cloning of full length rat and human MRP3 and rat MRP6. For MRP3, the cDNA-transfected cells were prepared to isolate the membrane vesicles. With thus prepared membrane vesicles, we could determine the s … More ubstrate specificity of MRP3. Although MRP3 accepts glucuronide conjugates as good substrates, glutathione conjugates were only poor substrates ; the transport properties of MRP3 were quite different from those of MRP1/2. Moreover, we have found that MRP3 is expressed in normal human liver and that its expression in HepG2 cells is induced by phenobarbital. We have also characterized the transport properties of organic anions using the isolated CMVs from rats and humans. Although comparable transport activity has been found among these two species, the transport activity of glutathione conjugates in humans was 1/5 of that in rats. If we consider the fact that MRP3 accepts glucuronide conjugates, but not glutathione conjugates, as good substrates and that MRP3 is expressed in normal human liver, but not in normal rat liver, it is suggested that the difference in the transport activity between rat and human CMVs can be accounted for by the difference in MRP3 expression levels. Since rat and human MRP3 are inducible, it is plausible that the difference in MRP3 expression level may result in the interindividual difference in the biliary excretion activity. Less

肝脏与肾脏一起在异种生物的排毒中起着重要作用。 In the present study, we have performed the cDNA cloning of canalicular multispecific organic anion transporter (cMOAT) and examined its function by using the membrane vegetables isolated from NIH3T3 cells translated with this cDNA.By examining the transport properties of organic anions with isolated bile canalicular membrane vegetables (CMVs), we have also suggested the presence of multiplicity for the transporters located on the胆管膜。此外，进行了CMOAT家族成员的cDNA克隆。使用RT-PCR，我们可以从EISAI高胆红素大鼠的肝脏中扩增MRP3和6的cDNA片段，其CMOAT功能在遗传性上有缺陷。我们还成功地获得了全长大鼠和人MRP3和大鼠MRP6的cDNA克隆。对于MRP3，准备cDNA转染的细胞以分离膜蔬菜。在这样准备的膜蔬菜的情况下，我们可以确定MMP3的ubstrate特异性。尽管MRP3接受谷氨酸结合物作为良好的底物，但谷胱甘肽结合物仅是较差的底物。 MRP3的运输特性与MRP1/2的运输特性完全不同。此外，我们发现MRP3在正常的人肝脏中表达，其在HEPG2细胞中的表达是由苯巴比妥诱导的。我们还使用来自大鼠和人类的分离的CMV来表征有机阴离子的运输特性。尽管在这两个物种中发现了可比的运输活性，但在大鼠中，谷胱甘肽结合物的运输活性为1/5。如果我们认为MRP3接受谷胱甘肽结合物，但不接受谷胱甘肽缀合物，作为良好的底物，并且MRP3在正常的人肝脏中表达，而在正常大鼠肝脏中不表达，则建议通过MRP3表达水平的差异来构成大鼠和人CMV之间的运输活性的差异。由于大鼠和人类MRP3是可诱导的，因此MRP3表达水平的差异可能导致胆道极端效应的个体差异是合理的。较少的