The Regulation of Human Hydroxysteroid Sulfotransferase by Nuclear Receptor ROR

描述(申请人提供)：这项建议的目标是探索维甲酸相关孤儿受体(RORS)在调节人类羟基类固醇磺基转移酶SULT2A1中的新作用，SULT2A1是一种对胆汁酸和许多其他外源和内生物质的新陈代谢至关重要的II相酶。此前已知RORS在组织发育和昼夜节律中发挥作用。在三种ROR亚型中，ROR？那RoR呢？在肝脏中表达，但其肝功能尚不清楚。最近的研究表明，某些肝脏CYP酶，如CYP7B1和CYP2C8，可以被Rors转录调控，这表明这些孤儿受体在异种和内生酶的调控中发挥了更广泛的作用。我们的初步结果表明：1)ROR？与人原代肝细胞中SULT2A1的表达呈负相关；抑制内源性SULT2A1基因在HepG2细胞中的表达；3)在SULT2A1基因启动子中发现一个ROR反应元件(RORE)，该元件与同一启动子上的CARE重叠；4)共转染ROR？可抑制CAR对SULT2A1基因启动子的正调控。根据我们的初步数据，我们假设RoR？和/或RoR？在人类羟基类固醇磺基转移酶SULT2A1的调节中具有以前未知的作用。具体地说，我们假设：1)ROR的表达式？和/或RoR？与SULT2A1基因在人肝脏中的表达呈负相关；2)人SULT2A1基因启动子是Rors的转录靶点。我们提出了两个具体的目标来检验我们的假设：(1)确定ROR的表达是否？那RoR呢？与SULT2A1在人肝脏中的表达相关；以及(2)确定ROR？那RoR呢？调控SULT2A1基因的表达。据我们所知，这项研究是首次系统评价ROR？的新功能。那RoR呢？在调节人体肝脏药物代谢酶方面。SULT2A1介导的胆汁酸硫化和解毒在预防和缓解胆汁淤积中起着重要作用。这项研究的结果可能有助于了解Rors在SULT2A1基因表达的个体间差异和患者的胆汁淤积倾向中的作用。以前，Rors因其在组织发育和昼夜节律中的作用而为人所知。目前的申请代表了一个创新的和范式转换的项目，符合NIH R21探索性发展研究资助计划的任务。 公共卫生相关性：本申请涉及维甲酸相关孤儿受体(RORs)对人类羟类固醇磺基转移酶(SULT2A1)的调节，SULT2A1是一种第二阶段药物代谢酶。ROR以前因其在组织发育和昼夜节律中的作用而闻名，目前的应用代表了一项创新和范式转换的项目，符合NIH R21探索性发展研究资助计划的任务。SULT2A1对胆汁酸的代谢和胆汁淤积的缓解很重要。这项研究的结果可能有助于了解Rors在SULT2A1基因表达的个体间差异和患者的胆汁淤积倾向中的作用。

DESCRIPTION (provided by applicant): The goal of this proposal is to explore the novel role of the retinoid-related orphan receptors (RORs) in the regulation of the human hydroxysteroid sulfotransferase SULT2A1, a Phase II enzyme important for the metabolism of bile acids and many other xenobiotics and endobiotics. RORs were previously known to play a role in tissue development and circadian rhythm. Among three ROR isoforms, ROR? and ROR? are expressed in the liver, but their hepatic function remains unknown. It has recently been reported that certain hepatic CYP enzymes, such as CYP7B1 and CYP2C8, can be transcriptionally regulated by RORs, suggesting a broader role of these orphan receptors in xeno- and endobiotic enzyme regulation. Our preliminary results showed that: 1) The expression of ROR? was negatively correlated to the expression of SULT2A1 in primary human hepatocytes; 2) Overexpression of ROR? inhibited the expression of endogenous SULT2A1 in HepG2 cells; 3) A ROR response element (RORE) has been identified in the SULT2A1 gene promoter that overlaps a CAR response element (CARE) on the same promoter; and 4) The positive regulation of SULT2A1 gene promoter by CAR was inhibited by the co-transfection of ROR?. Based on our preliminary data, we hypothesize that ROR? and/or ROR? have a previously unrecognized role in the regulation of the human hydroxysteroid sulfotransferase SULT2A1. Specifically, we hypothesize that: 1) The expression of ROR? and/or ROR? is negatively correlated to the expression of SULT2A1 in the human liver; and 2) The human SULT2A1 gene promoter is a transcriptional target of RORs. We propose two specific aims to test our hypotheses: (1) To determine whether the expression of ROR? and ROR? correlates to the expression of SULT2A1 in the human liver; and (2) To determine the molecular mechanism by which ROR? and ROR? regulate the expression of SULT2A1 gene. To our knowledge, this study represents the first attempt to systematically evaluate the novel function of ROR? and ROR? in regulating hepatic drug metabolizing enzymes in humans. SULT2A1-mediated bile acid sulfation and detoxification play an important role in the prevention and relief of cholestasis. Results from this study may help to understand the role of RORs in the interindividual variation of SULT2A1 gene expression and the propensity to cholestasis in patients. RORs were previously known for their roles in tissue development and circadian rhythm. The current application represents an innovative and paradigm-shifting project that meets the missions of the NIH R21 Exploratory Developmental Research Grant Program. PUBLIC HEALTH RELEVANCE: This application addresses the regulation of the human hydroxysteroid sulfotransferase (SULT2A1), a Phase II drug-metabolizing enzyme, by the retinoid-related orphan receptors (RORs). RORs are previously known for their roles in tissue development and circadian rhythm, the current application represents an innovative and paradigm-shifting project that meets the missions of the NIH R21 Exploratory Developmental Research Grant Program. SULT2A1 is important for the metabolism of bile acids and relief of cholestasis. Results from this study may help to understand the role of RORs in the interindividual variation of SULT2A1 gene expression and the propensity to cholestasis in patients.