中文摘要：

为探讨肝细胞核因子1α（HNF1α）对人胆汁酸受体（FXR）转录激活的作用及机制，将含HNF1α的真核表达载体（pcDNA3．1（＋）HNF1α）和含有FXR启动子的荧光素酶报告基因载体共转染人肝癌细胞系HepG2，检测转染细胞中荧光素酶活性并用半定量RT-PCR、免疫印迹法检测FXR的表达．QuikChange法对FXR启动子HNF1α可能结合位点进行突变，将包含突变点的重组荧光素酶报告质粒单独或与pcDNA3．1（＋）共同转染HepG2细胞，检测各组荧光素酶活性．根据凝胶电泳迁移率变化，分析HNF1α与FXR启动子区域的结合．结果发现，转染pcDNA3．1（＋）HNF1α可以上调FXR在HepG2细胞中的表达，并增强FXR启动子活性且具有剂量依赖性；-65～-48区域的点突变，导致FXR启动子活性明显降低，共转染pcDNA3．1（＋）HNF1α也不具有增强作用．结果提示，转录因子HNF1α能调控FXR基因表达，其机制为：HNF1α与FXR启动子区域-65～-48区域的反向半位点结合，发挥其反式激活作用．

英文摘要：

To investigate the regulation of FXR promoter activity by HNF1α and its mechanism, the HNF1α expression vector （pcDNA 3.1 （ ＋ ）HNF1α） and the luciferase reporter vector containing the FXR promoter were co-transfected into HepG2 cell line. The luciferase activity of transfected HepG2 was determined and FXR expression was detected by semi-quantitative RT-PCR and Western blotting. The binding sites of HNF1α to FXR promoter were mutated using QuikChange method. These recombined luciferase reporter vectors containing the mutated sites were transfected into HepG2 cell alone or with pcDNA 3.1 （ ＋ ） HNF1α. The luciferase activity of transfected ceils was determined again. The interaction with FXR promoter was performed by electrophoretic mobility shift assay （EMSA）. Results showed that pcDNA 3.1 （＋）HNFla transfection could up-regulate FXR expression of HepG2 ceils and simultaneously enhance the promoter activity of FXR gene in a dose-dependent manner. The mutation of FXR promoter at - 65 to - 48 resulted in a striking decrease of promoter activity and co-transfection with pcDNA 3.1 （ ＋ ） HNF1α did not enhance the promoter activity. HNF1α could bind to the - 65 to - 48 region in human FXR promoter. These results suggest that HNF1α could transactivate the FXR promoter activity. The mechanism may lie in that HNF1α bind to the inverse half site at - 65 to - 48, then activate the promoter activity.