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Analysis of functions of the cholesterol export/bile acid uptake transporters, and the effects of food factors on their activities

胆固醇输出/胆汁酸摄取转运蛋白的功能分析以及食物因素对其活性的影响

基本信息

批准号：
14360069
负责人：
RYUICHIRO Sato
金额：
$ 10.3万
依托单位：
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：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14360069/
关键词：
FXR BABP IBAT bile acid CDCA ABCG5 ABCG8 コレステロール小腸排出トランスポーター LXR Caco-2

项目摘要

(1)Functions of the bile acid-binding proteinBased on the fact that both of the bile acid-binding protein (BABP) and FXR can bind bile acids, we examined whether BABP affects the FXR activity. In the culture cells stably expressing BABP, induction of the FXR activity was observed by chenodeoxycholic acid (CDCA) imported independently on the ileum bile acid transporter (IBAT), suggesting that the efficient exchange of bile acids between two proteins might exist. In the cells expressing IBAT transiently, the same phenomenon was observed. Furthermore, conjugated bile acids up taken by IBAT stimulated the FXR activity more significantly. It was thought that the more efficient absorption of conjugated bile acids than unconjugated ones by IBAT in the presence of BABP can explain this finding.(2)Establishment of assay systems for evaluating the activation of FXR and the ligand-binding affinityThe current luciferase assay system enabled us to evaluate the FXR-stimulating effects of food ingredients. We succeeded to find out some factors that stimulate or decline the FXR activity among 160 kinds of food ingredients. We also established a new assay system to evaluate the ligand-binding affinity for food ingredients to the ligand-binding domain of FXR, which detect the activity of alkaline phosphatase fused to the nuclear receptor coactivator recruited by the binding of some factors to the ligand-binding domain. We have been analyzing the binding affinity of food ingredients using this assay system.

(1)胆汁酸结合蛋白的功能基于胆汁酸结合蛋白（BABP）和FXR均能结合胆汁酸，我们考察了BABP是否影响FXR的活性。在稳定表达BABP的培养细胞中，观察到在回肠胆汁酸转运体（IBAT）上独立导入的鹅脱氧胆酸（CDCA）诱导了FXR活性，表明两种蛋白之间可能存在胆汁酸的有效交换。在短暂表达IBAT的细胞中，也观察到同样的现象。此外，IBAT吸收的共轭胆汁酸更显著地刺激了FXR活性。人们认为，在BABP存在的情况下，IBAT对共轭胆汁酸的吸收比非共轭胆汁酸更有效，这可以解释这一发现。(2)建立评价FXR活化和配体结合亲和力的分析系统现有的荧光素酶分析系统使我们能够评价食品成分的FXR刺激作用。我们成功地找出了160种食品成分中刺激或抑制FXR活性的因素。我们还建立了一个新的检测系统来评估食品成分与FXR配体结合域的亲和力，该系统检测了一些因子与配体结合域结合而募集的核受体共激活因子融合的碱性磷酸酶的活性。我们一直在使用该检测系统分析食品成分的结合亲和力。