The Regulation of Human Hydroxysteroid Sulfotransferase by Nuclear Receptor ROR

描述（由申请人提供）：本提案的目的是探索类视黄醇相关孤儿受体（RORs）在调节人羟基类固醇磺基转移酶SULT2A1中的新作用，SULT2A1是一种对胆酸和许多其他外源性和内源性代谢很重要的II期酶。先前已知RORs在组织发育和昼夜节律中起作用。在三个ROR异构体中，ROR？和ROR吗?在肝脏中表达，但其肝功能尚不清楚。最近有报道称，某些肝脏CYP酶，如CYP7B1和CYP2C8，可以通过RORs进行转录调节，这表明这些孤儿受体在外源性和内源性酶调节中具有更广泛的作用。我们的初步结果表明：1)ROR？与SULT2A1在人原代肝细胞中的表达呈负相关；2) ROR过表达？抑制HepG2细胞内源性SULT2A1的表达；3)在SULT2A1基因启动子中发现了一个ROR反应元件（RORE），该元件与同一启动子上的CAR反应元件（CARE）重叠；4) CAR对SULT2A1基因启动子的正调控作用被ROR共转染抑制。根据我们的初步数据，我们假设ROR？和/或ROR吗?在人类羟基类固醇硫转移酶SULT2A1的调节中有一个以前未被认识到的作用。具体来说，我们假设：1)ROR？和/或ROR吗?与SULT2A1在人肝脏中的表达呈负相关；2)人类SULT2A1基因启动子是RORs的转录靶点。我们提出了两个具体目标来检验我们的假设：(1)确定ROR？和ROR吗?与人肝脏中SULT2A1的表达相关；(2)确定ROR的分子机制。和ROR吗?调节SULT2A1基因的表达。据我们所知，这项研究首次尝试系统地评估ROR的新功能。和ROR吗?在调节人类肝脏药物代谢酶。sult2a1介导的胆汁酸硫酸化和解毒在预防和缓解胆汁淤积中起重要作用。本研究的结果可能有助于了解RORs在SULT2A1基因表达个体间变异和患者胆汁淤积倾向中的作用。之前，RORs因其在组织发育和昼夜节律中的作用而闻名。目前的申请代表了一个创新和范式转换的项目，满足了NIH R21探索性发展研究资助计划的任务。

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.