ANALYSIS OF ERYTHROCYTE SODIUM-PHOSPHATE COTRANSPORTER

描述（改编自申请人的摘要）：本项目的目标 是了解钠-磷酸盐共转运的分子机制， 钠-锂反向转运Na-PO 4共转运是一种重要的 通过其主动运输对所有哺乳动物细胞至关重要的生理过程 无机磷酸盐，一种中心代谢物。钠-锂对输运是一种 将锂泵出细胞的重要医学细胞机制。其 红细胞中的红细胞比率与Li疗法的有效性呈负相关 在双相情感障碍中， 高血压尽管这些过程很重要， 因为负责的分子还没有被识别出来， 在模型系统中充分表征。最近，在以下方面取得了进展： 这两个领域。有间接的动力学和药理学 有证据表明，“大脑特异性”基因，BNP 1（或相关的同种型），是 K562红白血病细胞和红细胞中的Na-PO 4协同转运蛋白的 该项目将测试三个假设。假设一：BNP 1是红细胞 Na-PO 4协同转运蛋白。这一假设将在具体目标1中进行检验， 证明BNP 1是存在于人红细胞生成中的主要同种型， 细胞和K562细胞以及特异性目的2中，通过证明BNP 1蛋白 存在于这些细胞和成熟红细胞中。假设二： 红细胞钠-磷酸盐协同转运蛋白也是主要的钠-钠交换器。这 将在具体目标3中通过确定以下物质的化学计量来检验假设： Na-PO 4共转运和具体目标4中的新Na转运 由BNP 1在卵母细胞和HEK 293细胞中的异源表达引起 使用新的诱导型启动子系统。假设三：Na-PO 4协同转运蛋白 是钠-锂逆向转运的长期分子基础。这一假设 将在《特定目标5》中通过确定新的钠-锂反向转运进行测试 在表达BNP 1的卵母细胞和HEK 293细胞中。

DESCRIPTION (Adapted from the Applicant's Abstract): The goal of this project is to understand the molecular mechanism of sodium-phosphate cotransport and sodium-lithium countertransport. Na-PO4 cotransport is an important physiological process vital to all mammalian cells through its active transport of inorganic phosphate, a central metabolite. Na-Li countertransport is a medically important cellular mechanism that pumps lithium out of cells. Its rate in erythrocytes inversely correlates with the effectiveness of Li therapy in bipolar disease and directly correlates with the development of essential hypertension. Despite their importance, these processes are not well understood because the responsible molecules have not been identified or have not been adequately characterized in model systems. Recently there has been progress in both of these areas. There is circumstantial kinetic and pharmacological evidence that the "brain specific" gene, BNP1 (or a related isoform), is the Na-PO4 cotransporter in K562 erythroleukemic cells and erythrocytes. The project will test three hypotheses. Hypothesis I: BNP1 is the erythrocyte Na-PO4 cotransporter. This hypothesis will be tested in Specific Aim 1 by demonstrating that BNP1 is the major isoform present in human erythropoietic cells and K562 cells and in Specific Aim 2 by demonstrating that BNP1 protein is present in those cells and mature erythrocytes. Hypothesis II: the erythrocyte Na-phosphate cotransporter is also the major Na-Na exchanger. This hypothesis will be tested in Specific Aim 3 by determining the stoichiometry of Na-PO4 cotransport and in Specific Aim 4 by characterizing the new Na transport caused by the heterologous expression of BNP1 in oocytes and in HEK293 cells using a new inducible promoter system. Hypothesis III: the Na-PO4 cotransporter is the long sought molecular basis for Na-Li countertransport. This hypothesis will be tested in Specific Aim 5 by determining the new Na-Li countertransport in BNP1 expressing oocytes and HEK293 cells.