TOXICOLOGICAL SIGNIFICANCE OF BILE SALT EXPORT PUMP

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。药物引起的肝毒性通常表现为胆汁淤积、肝炎或两者兼而有之。胆汁淤积症是由胆汁流动受损引起的，表现为一系列胆汁淤积症状。已发现许多药物可引起胆汁淤积。虽然许多因素可能导致胆汁淤积，但最近认为小管分泌紊乱是一个主要的决定因素。遗传和生化研究已经证实胆盐输出泵（BSEP）负责胆汁酸的分泌。BSEP功能降低或缺陷与遗传性和获得性胆汁淤积直接相关。该项目的长期目标是验证异种生物通过不同但功能相关的核受体途径的转录调节来调节BSEP表达的假设。本试点项目的具体目的包括：(1)确定外源性药物对BSEP表达的调控模式；(2)定位BSEP启动子中的顺式作用元件，这些元件负责通过这些化学物质调节BSEP的表达。第一个特定目的是为了验证这些化学物质通过改变转录速率或mRNA稳定性来调节BSEP表达的假设。提出了两种实验方法来检验这一假设：(a)将对这些化学品进行剂量反应和时间过程研究；(b)和细胞将与异种生物制剂和转录抑制剂共同处理，并监测BSEP mRNA的水平。第二个特定目的是为了测试这些化学物质对BSEP的转录调节是序列特异性的假设。设计了两种实验方法来检验这一假设：(a)将制备一种含有可能的异种生物反应成分的BSEP启动子，并测试其对这些化学品的反应性；(b) BSEP启动子的缺失突变体将定位功能重要的调控表达序列。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Drug-induced hepatotoxicity is generally presented as cholestasis, hepatitis, or both. Cholestasis is caused by impaired bile flow and exhibits a series of bile-stagnated symptoms. Many drugs have been found to induce cholestasis. Although many factors likely contribute to cholestasis, disrupted canalicular secretion is recently recognized as a major determinant factor. Genetic and biochemical studies have established that the bile salt export pump (BSEP) is responsible for the secretion of bile acids. Decreased or defective BSEP function is linked directly to hereditary and acquired cholestasis. The long-term goal of the proposed project is to test the hypothesis that the regulated expression of the BSEP by xenobiotics is achieved by transcription regulation through distinct but functionally related nuclear receptor pathways. The specific aims of this pilot project include: (1) to determine the regulatory modes of BSEP expression by xenobiotics; and (2) to locate cis-acting elements in the BSEP promoter responsible for the regulated expression of BSEP by those chemicals. The first specific aim is designed to test the hypothesis that the regulated expression of BSEP by these chemicals is achieved by either altering transcription rate or mRNA stability. Two experimental approaches are proposed to test this hypothesis: (a) dose-response and time course studies will be conducted with these chemicals; (b) and cells will be co-treated with xenobiotics and transcription inhibitors, and the level of BSEP mRNA will be monitored. The second specific aim is designed to test the hypothesis that transcription regulation of BSEP by these chemicals is sequence-specific. Two experimental approaches are designed to test the hypothesis: (a) A BSEP promoter containing potential xenobiotic-response elements will be prepared and tested for the responsiveness to these chemicals; and (b) deletion mutants of the BSEP promoter will be made to locate functionally important sequences for the regulated expression.