Farnesoid X receptor, hepatocyte nuclear factors 1α and 3β are essential for transcriptional activation of the liver-specific organic anion transporter-2 gene
Farnesoid X receptor, hepatocyte nuclear factors 1α and 3β are essential for transcriptional activation of the liver-specific organic anion transporter-2 gene
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DOI：
10.1007/s00535-006-1784-3
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发表时间：
2006-04-01
影响因子：
6.3
通讯作者：
Unno, M
中科院分区：
文献类型：
--
作者：
Ohtsuka, H;Abe, T;Unno, M
背景我们分离了人肝脏特异性有机阴离子转运蛋白基因LST-2（OATP 8/SLCO 1B 3），该基因仅在肝细胞的基底外侧膜中表达。在这项研究中，我们分析了LST-2基因在肝细胞来源的细胞中的转录调控和胆汁酸的影响。使用人LST-2启动子-荧光素酶报告质粒在各种浓度的胆汁酸下测量LST-2基因的转录活性。对法尼醇X受体（FXR）、肝细胞核因子（HNF）1 α和HNF 3 β进行电泳迁移率变动分析。荧光素酶分析表明，LST-2基因5 ′侧翼区的-180 ~-20 bp的区域决定了LST-2的转录活性。通过定点突变分析，发现FXR、HNF 1 α和HNF 3 β的共有结合位点在LST-2基因的转录活性中起重要作用。通过电泳迁移率变动分析，我们观察到FXR、HNF 1 α和HNF-3 β的特异性蛋白-DNA复合物。荧光素酶活性增加五倍时，鹅脱氧胆酸盐或脱氧胆酸盐。北方印迹分析显示，鹅脱氧胆酸盐或脱氧胆酸盐以剂量依赖方式增加LST-2的表达。这项研究表明，LST-2基因的转录受三种转录因子FXR、HNF 1 α和HNF 3 β的调控。HNF 1 α和HNF 3 β可能有助于其肝脏特异性表达，FXR可能在胆汁酸对其转录激活中发挥作用。
Background. We isolated the human liver-specific organic anion transporter gene, LST-2 (OATP8/SLCO1B3), which is exclusively expressed in the basolateral membrane of the hepatocytes. In this study, we analyzed the transcriptional regulation of the LST-2 gene in hepatocyte-derived cells and the effect of bile acid.Methods. Transcriptional activity of the LST-2 gene was measured using a human LST-2 promoter-luciferase reporter plasmid under various concentrations of bile acids. Electrophoresis mobility shift assays of farnesoid X receptor (FXR), hepatocyte nuclear factor (HNF) 1 alpha, and HNF3 beta were performed.Results. Luciferase analysis showed that the 5'-flanking region from -180 to -20bp is responsible for LST-2 transcriptional activity. By site-directed mutation analysis, it was revealed that the consensus binding sites for FXR, HNF1 alpha, and HNF3 beta play important roles in the transcriptional activity of the LST-2 gene. By electrophoresis mobility shift assay, we observed specific protein-DNA complexes of FXR, HNF1 alpha, and HNF-3 beta. Luciferase activity was increased fivefold when chenodeoxycholate or deoxycholate were added. Northern blot analyses revealed that the expression of LST-2 was increased by addition of chenodeoxycholate or deoxycholate in a dose-dependent manner.Conclusions. This study demonstrated that the transcription of the LST-2 gene is regulated by three transcription factors, FXR, HNF1 alpha, and HNF3 beta. HNF1 alpha and HNF3 beta might contribute to its liver-specific expression, and FXR might play a role in its transcriptional activation by bile acids.