A Novel Regulation of the Phase II Enzyme Estrogen Sulfotransferase

描述（由申请人提供）：雌激素磺基转移酶（EST或SULT 1 E1）是一种II相结合酶，以其磺化和灭活雌激素（一种抗炎激素）的活性而闻名。这是因为磺化雌激素不能结合并激活雌激素受体。EST的转录受核受体的调控。然而，目前尚不清楚EST是否以及如何受到炎症刺激的调节，以及炎症反应性调节EST的结果是什么。雌激素的平衡合成和代谢密切调节雌激素的稳态。使雌激素失活的关键代谢途径是通过EST介导的硫酸化。然而，还没有测试EST的表达和调节是否影响宿主对炎症刺激的敏感性。结果表明：1）细菌脂多糖（LPS）处理小鼠或盲肠结扎穿孔（CLP）脓毒症模型小鼠，在一定时间内诱导肝脏特异性EST表达和活性。 呈剂量依赖性; 2）肝枯否细胞的耗竭减弱了LPS诱导的EST; 3）LPS处理小鼠的EST诱导与雌激素诱导的子宫上皮细胞增殖和雌激素应答基因表达的抑制以及循环雌二醇水平的降低有关; 4）LPS诱导的EST似乎是核受体非依赖性的。5）EST是一个潜在的NF-κB靶基因，在EST基因启动子上有几个推测的NF-κ B结合位点：6）EST的炎症调节在雄性小鼠和人肝细胞中是保守的; 7）EST-/-小鼠的LPS-反应性炎症反应减弱，可能是由于雌激素活性增加。基于这些观察结果，我们推测EST受炎症刺激的调节，并且EST的表达和调节影响宿主对炎症刺激的敏感性。具体地说，我们假设：1）LPS和CLP诱导EST的表达，并因此剥夺雌激素; 2）TLR 4是必需的炎症反应调节EST，和EST是NF-κ B的转录靶点;和3）EST消融减弱小鼠从，而在肝脏中的转基因过表达的EST，LPS和CLP诱导的炎症反应敏感的小鼠。我们提出了三个具体的目标来验证我们的假设：1）以确定是否炎性刺激剥夺雌激素在EST依赖的方式; 2）以确定的分子机制，炎症刺激调节EST的表达;和3）以确定是否EST消融减弱小鼠，而在肝脏中的转基因EST过表达的小鼠，LPS和CLP诱导的炎症反应的敏感性。据我们所知，这项研究代表了第一次尝试评估的调节EST炎症刺激和雌激素稳态的影响，这种调节。这项研究具有医学意义，特别是在女性健康方面。我们推测，炎症与EST的相互调节可能是炎症的内分泌调节机制之一。阐明这一机制可能为预防和治疗炎症相关疾病提供新的治疗靶点。

DESCRIPTION (provided by applicant): Estrogen sulfotransferase (EST or SULT1E1) is a phase II conjugating enzyme best known for its activity in sulfonating and deactivating estrogens, an anti-inflammatory hormone. This is because sulfonated estrogens fail to bind to and activate the estrogen receptor. EST has been shown to be transcriptionally regulated by nuclear receptors. However, it is unclear whether and how EST is regulated by inflammatory stimuli and what is the consequence of inflammation responsive regulation of EST. The estrogen homeostasis is tightly regulated by balanced synthesis and metabolism of estrogens. A critical metabolic pathway to deactivate estrogens is through EST-mediated sulfation. However, it has not been tested whether the expression and regulation of EST affect the host's sensitivity to inflammatory stimuli. Our preliminary results showed that: 1) Treatment of mice with bacterial lipopolysaccharide (LPS) or subjected mice to the cecal ligation and puncture (CLP) model of sepsis induced the expression and activity of EST specifically in the liver in time- and dose-dependent manner; 2) Depletion of liver Kupffer cells attenuated the EST induction by LPS; 3) The EST induction in LPS-treated mice was associated with an inhibition of estrogen-induced uterine epithelial proliferation and estrogen responsive gene expression, as well as a decreased circulating level of estradiol; 4) The LPS induction of EST appeared to be nuclear receptor- independent. In contrast, the CLP induction of EST was abolished in Toll-like receptor 4 knockout (TLR4-/-) mice; 5) EST is a potential NF-κB target gene, and several putative NF-kB binding sites have been predicted in the EST gene promoter; 6) The inflammatory regulation of EST was conserved in male mice, as well as in human liver cells; 7) EST-/- mice were attenuated from an LPS-responsive inflammatory response, likely due to increased estrogen activities. Based on these observations, we hypothesize that EST is subject to the regulation by inflammatory stimuli; and reciprocally, the expression and regulation of EST influence the host's sensitivity to inflammatory stimuli. Specifically, we hypothesize that: 1) LPS and CLP induce the expression of EST, and consequently deprive estrogens; 2) TLR4 is required for the inflammatory responsive regulation of EST, and EST is a transcriptional target of NF-kB; and 3) EST ablation attenuates mice from, whereas transgenic overexpression of EST in the liver sensitizes mice to, LPS- and CLP-induced inflammatory responses. We propose three specific aims to test our hypotheses: 1) To determine whether the inflammatory stimuli deprive estrogens in an EST-dependent manner; 2) To determine the molecular mechanism by which the inflammatory stimuli regulate the expression of EST; and 3) To determine whether EST ablation attenuates mice from, whereas transgenic overexpression of EST in the liver sensitizes mice to, LPS- and CLP-induced inflammatory response. To our knowledge, this study represents the first attempt to evaluate the regulation of EST in response to inflammatory stimuli and the implications of this regulation in estrogen homeostasis. The proposed study is of medical significance, especially in women's health. We reason that the reciprocal regulation of inflammation and EST may represent a yet to be explored mechanism of endocrine regulation of inflammation. Elucidation of this mechanism may provide a novel therapeutic target for the prevention and treatment of inflammation related diseases.