Molecular Pharmacology of Estrogen Sulfotransferase

描述（由申请人提供）：雌激素磺基转移酶（EST）是一种II相代谢酶，可磺基结合并灭活类固醇激素雌激素。虽然已经了解了很多关于EST和相关类固醇磺基转移酶的生物化学、结构生物学和药物遗传学，但EST和其他类固醇磺基转移酶的分子药理学和体内功能仍然不完全清楚。这项建议的目的是测试的假设，EST是一个重要的肝外结合酶，调节组织雌激素的敏感性，并在局部雌激素代谢和稳态中发挥生理作用。本研究的长期目标是了解EST活性的变化，通过遗传（药物遗传学）或环境因素（药物-药物相互作用），可能会改变组织的雌激素敏感性下的生理或治疗设置。在我们的初步研究中，我们已经产生了一个EST敲除（KO）小鼠，这将用于测试我们的假设。在这项提议中，我们将追求以下具体目标：具体目标1：测试子宫和胎盘EST表达防止胎儿雌激素毒性的假设。我们初步发现雌性EST KO小鼠生育能力降低，这一假设得到了支持。在缺乏EST的情况下，未代谢的雌激素可能对发育中的胎儿产生毒性或干扰分娩过程。药理学方法，如雌激素受体拮抗剂的使用将应用于这项调查。具体目标2：验证EST在维持Leydig细胞胆固醇稳态中发挥生理作用的假设。我们已经发现EST KO小鼠Leydig细胞异常积累中性脂质。我们将确定这些细胞中的异常脂质积聚是否由清道夫受体，B类，I型（SRBI）介导，以及它是否依赖于雌激素受体功能。生物化学、分子生物学和遗传学方法将用于解决这一问题。具体目标3：为了验证EST保护Leydig细胞免受雌激素诱导的类固醇生成抑制的假设，并且这种抑制发生在底物动员步骤或P450 17 α-羟化酶步骤。具体目标4：为了验证EST在雄性生殖道附属结构中以雄激素依赖方式表达的假说。我们对EST KO小鼠的初步研究支持了具体目标3和4中的两个假设。拟议的研究将提供一个分子基础，了解雌激素磺基转移酶的体内药理学和生理学的原型II相类固醇磺基共轭酶。

DESCRIPTION (provided by applicant): Estrogen sulfotransferase (EST) is a phase II metabolic enzyme that sulfoconjugates and inactivates the steroid hormone estrogen. Although much has been learned on the biochemistry, structural biology and pharmacogenetics of EST and related steroid sulfotransferases, the molecular pharmacology and in vivo function of EST and other steroid sulfotransferases remain incompletely understood. The goal of this proposal is to test the hypothesis that EST is a significant extrahepatic conjugation enzyme that regulates tissue estrogen sensitivity, and as such plays a physiological role in local estrogen metabolism and homeostasis. The long-term objective of this study is to understand how variation in EST activity, through either genetic (pharmacogenetics) or environmental factors (drug-drug interaction), might alter tissue estrogen sensitivity under physiological or therapeutic settings. In our preliminary studies, we have generated an EST knockout (KO) mouse which will be used to test our hypothesis. In this proposal, we will pursue the following specific aims: Specific aim 1: To test the hypothesis that uterine and placental EST expression prevents fetal estrogen toxicity. This hypothesis is supported by our preliminary finding that female EST KO mice have reduced fertility. In the absence of EST, unmetabolized estrogen may become toxic to the developing fetus or disturb the parturition process. Pharmacological approaches such as the use of estrogen receptor antagonists will be applied to this investigation. Specific aim 2: To test the hypothesis that EST plays a physiological role in maintaining cholesterol homeostasis in Leydig cells. We have found that EST KO mouse Leydig cells abnormally accumulate neutral lipids. We will determine if abnormal lipid accumulation in these cells is mediated by the Scavenger Receptor, Class B, Type I (SRBI) and whether it is dependent on estrogen receptor function. Biochemical, molecular biological and genetic approaches will be applied to address this question. Specific aim 3: To test the hypothesis that EST protects Leydig cells from estrogen-induced inhibition of steroidogenesis and that such inhibition occurs either at the substrate mobilization step or at the P450 17a-hydroxylase step. Specific aim 4: To test the hypothesis that EST is expressed in the accessory structures of the male reproductive tract in an androgen-dependent manner. Both hypotheses in Specific aim 3 and 4 are supported by our preliminary study of the EST KO mice. The proposed studies will provide a molecular basis for understanding the in vivo pharmacology and physiology of estrogen sulfotransferase as a prototypical phase II steroid sulfoconjugation enzyme.