Regulation Of Inorganic Phosphorus (Pi) Metabolism By Estrogen

雌激素对无机磷 (Pi) 代谢的调节

• 批准号: 8527766
• 负责人: HASSANE AMLAL
• 金额: $ 28.01万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-26 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8527766
• 关键词: 3' Untranslated Regions; Acute; Address; Adverse effects; Agonist; Animal Model; Animals; Apical; Binding; Biochemical; Biochemical Process; Blood; Bone Matrix; Brush Border; COS-7 Cell; Cardiovascular system; Cell Culture Techniques; Cell Line; Cells; Chronic; Clinical Research; Complement; Complementary DNA; Creatinine clearance measurement; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Down-Regulation; Eating; Equilibrium; Estrogen Receptors; Estrogens; Excretory function; Exhibits; Experimental Models; Factor V; Family; Female; Functional disorder; GTP-Binding Proteins; Genetic; Gonadal Steroid Hormones; Homeostasis; Hormones; Hour; Hypophosphatemia; Implant; In Vitro; Intestines; Intracellular Signaling Proteins; Kidney; Knockout Mice; Laboratories; Length; MAP Kinase Signaling Pathways; MDCK cell; Maintenance; Mediating; Membrane; Messenger RNA; Metabolism; Minerals; Molecular; Mus; Nuclear Receptors; Oocytes; PDZ protein; Parathyroid gland; Pathway interactions; Patients; Phospholipids; Phosphorus; Physiological; Physiological Processes; Placebos; Plasma; Play; Postmenopausal Osteoporosis; Protein Biosynthesis; Proximal Kidney Tubules; Rattus; Regulation; Regulatory Pathway; Role; Serum; Sodium; Suspension substance; Suspensions; Techniques; Therapeutic; Tubular formation; Urine; Woman; Xenopus laevis; absorption; bone loss; cis acting element; in vivo; inorganic phosphate; mRNA Stability; member; non-genomic; novel; null mutation; pill; prevent; public health relevance; receptor; receptor coupling; research study; tool; trafficking; urinary; wasting

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to study the regulation of inorganic phosphorus (Pi) homeostasis by female sex steroids, mainly Estrogen (E2). Inorganic phosphorus (Pi) is an important mineral that is essential to various important physiological and biochemical processes. Clinical studies have shown that women treated with E2 exhibited renal Pi wasting and hypophosphatemia. Both kidney and intestine play an important role in the control and maintenance of Pi homeostasis. Studies have shown that E2 stimulates Pi absorption in the intestine; however, the effect of E2 on renal handling of Pi is poorly understood. Our preliminary studies showed that E2 treatment of ovariectomized (OVX) rat caused urinary Pi wasting and hypophosphatemia. This effect resulted from a specific downregulation of type IIa apical sodium-dependent phosphate cotransporter (NaPi-IIa), independently of changes in food intake and parathyroid hormone (PTH) levels. In vitro studies indicated that this effect is mediated through a posttranscriptional mechanism involving the mRNA stability of NaPi-IIa. To fully characterize this new regulatory pathway of Pi metabolism, we propose to perform the experiments described in the following two Specific Aims. Aim 1: Characterize the rapid, non-genomic effect of E2 on Pi handling by the kidney. The effects of E2 on urinary Pi excretion, NaPi-IIa transport activity, and its membrane expression (trafficking) will be examined in female OVX rats. The transduction pathways mediating this effect will be investigated using both in vitro and in vivo studies involving PDZK1 and NHERF1 knout mice. These studies will be complemented with in vitro experiments, which will examine the expression and transport activity of NaPi-IIa using proximal tubule suspensions, Xenopus Laevis oocytes and MDCK cells. Aim 2: Determine the molecular mechanisms and transduction pathways mediating the chronic effect of E2 on renal Pi handling in OVX female rats. We will use the pharmacological agonists as well as mice with genetic deletion of estrogen receptors ER? or ER?. The role of mRNA stability and 3'UTR in E2- induced downregulation of NaPi-IIa will be determined using COS7 cells transfected with NaPi-IIa full- length cDNA. These studies will use both animal models as well as cell culture experiments. Once completed, these studies will provide us with a full characterization of E2 as a novel regulatory factor of Pi homeostasis with a clear understanding of its effects on renal handling of Pi. We propose that E2 could be an important and efficient therapeutic tool that can prevent hyperphosphatemia and its adverse effects on cardiovascular system in conditions associated with parathyroid gland dysfunction. PUBLIC HEALTH RELEVANCE: Inorganic phosphorus (Pi) is an important mineral involved in several functions of the body. The blood level of Pi is controlled by estrogen, which increases its excretion in the urine. This effect should be considered when prescribing estrogen, and this hormone can also be used when blood level of Pi is high (hyperphosphatemia).

描述（由申请人提供）：本提案的长期目标是研究女性性类固醇，主要是雌激素（E2）对无机磷（Pi）稳态的调节。无机磷（Pi）是一种重要的矿物质，对于各种重要的生理生化过程至关重要。临床研究表明，接受 E2 治疗的女性表现出肾 Pi 消耗和低磷血症。肾脏和肠道在控制和维持 Pi 稳态中发挥着重要作用。研究表明E2可刺激肠道对Pi的吸收；然而，E2 对肾脏处理 Pi 的影响知之甚少。我们的初步研究表明，E2 治疗卵巢切除 (OVX) 大鼠会导致尿 Pi 消耗和低磷血症。这种效应是由 IIa 型顶端钠依赖性磷酸盐协同转运蛋白 (NaPi-IIa) 的特异性下调引起的，与食物摄入量和甲状旁腺激素 (PTH) 水平的变化无关。体外研究表明，这种效应是通过涉及 NaPi-IIa mRNA 稳定性的转录后机制介导的。为了充分表征 Pi 代谢的这种新调控途径，我们建议进行以下两个具体目标中描述的实验。目标 1：表征 E2 对肾脏处理 Pi 的快速、非基因组效应。将在雌性 OVX 大鼠中检查 E2 对尿 Pi 排泄、NaPi-IIa 转运活性及其膜表达（转运）的影响。将使用涉及 PDZK1 和 NHERF1 基因敲除小鼠的体外和体内研究来研究介导这种效应的转导途径。这些研究将与体外实验相补充，这些实验将使用近端小管悬浮液、非洲爪蟾卵母细胞和 MDCK 细胞检查 NaPi-IIa 的表达和转运活性。目标 2：确定 E2 对 OVX 雌性大鼠肾脏 Pi 处理的慢性影响的分子机制和转导途径。我们将使用药理学激动剂以及雌激素受体 ER? 基因缺失的小鼠。还是急诊室？ mRNA稳定性和3'UTR在E2诱导的NaPi-IIa下调中的作用将使用用NaPi-IIa全长cDNA转染的COS7细胞来确定。这些研究将使用动物模型和细胞培养实验。一旦完成，这些研究将为我们提供 E2 作为 Pi 稳态的新型调节因子的完整表征，并清楚地了解其对肾脏处理 Pi 的影响。我们认为 E2 可能是一种重要且有效的治疗工具，可以预防高磷血症及其在甲状旁腺功能障碍相关疾病中对心血管系统的不利影响。 公众健康相关性：无机磷 (Pi) 是一种重要的矿物质，参与身体的多种功能。 Pi 的血液水平受雌激素控制，雌激素会增加其在尿液中的排泄。在开雌激素处方时应考虑这种效应，并且当血液 Pi 水平高（高磷血症）时也可以使用这种激素。