REGULATION OF THE SODIUM/MYO-INOSITOL COTRANSPORTER

肌醇是存在于所有细胞中的丰富的糖。它有两个非常 重要功能：1）是磷脂酰肌醇的前体， 所有细胞质膜的重要组成部分，2）它是一种 相容的渗透剂，即-与钠和钾相反， 细胞内浓度可增加10倍而不干扰细胞 功能虽然血浆中肌醇的浓度为0.05mM， 其在大多数细胞中的浓度为10 - 20 mM。它进入细胞对抗这样一种 钠/肌醇共转运蛋白上陡峭浓度梯度， 由钠的电化学梯度驱动。虽然细胞内 肌醇的缺乏与神经病有关， 糖尿病肾病，几乎没有什么是已知的， 协同运输或其监管。 该项目旨在了解该功能， 通过克隆调节钠/肌醇协同转运蛋白， 从培养的肾细胞中测序它的cDNA， 髓质，提高他们的肌醇水平，以应对> 80毫米 高渗在那个时候，协同转运蛋白的活性增加， 有证据表明协同转运蛋白的mRNA增加了。cDNA将是 测序以揭示协同转运蛋白的一级结构， 有助于产生抗体。抗体将 用于定量肾细胞中共转运蛋白的数量， 确定细胞是否积累了更多的肌醇，因为有 更多的协同转运蛋白，如果有更多，这是否是由于 协同转运蛋白的合成增加和/或降解减少。的 cDNA将用于构建RNA探针以测量细胞mRNA水平， 共同运输者以确定实际上是否有增加 协同转运蛋白mRNA以及mRNA的合成和/或降解是否 监管.如果mRNA合成增加，协同转运蛋白的基因 将被克隆，以便调节高渗性的机制， 可以研究其他因素。cDNA将用于开发探针， 克隆钠/肌醇协同转运蛋白的cDNA， 肾脏和小肠的顶端质膜，其功能是 将肌醇从管腔运输到血液。序列数据应该会产生 关于导致协同转运蛋白被 位于一些上皮细胞的顶端质膜和 其他上皮细胞的基底外侧质膜。

Myo-inositol is an abundant sugar present in all cells. It has two very important functions: 1) It is a precursor of phosphatidylinositol, an important component of the plasma membrane of all cells, and 2) it is a compatible osmolyte, i.e.-in contrast to sodium and potassium, its intracellular concentration can increase 10 fold without disturbing cell function. Although the concentration of myo-inositol in plasma is 0.05mM, its concentration in most cells is lO-2OmM. It enters cells against such a steep concentration gradient on a sodium/myo-inositol cotransporter that is driven by the electrochemical gradient for sodium. Although intracellular deficiency of myoinositol has been implicated in the neuropathy and nephropathy of diabetes mellitus, virtually nothing is known about the cotransporter or its regulation. This project is designed to gain an understanding of the function and regulation of the sodium/myo-inositol cotransporter by cloning and sequencing its cDNA from cultured kidney cells, that like the renal medulla, raise their myo-inositol levels to >80mM in response to hypertonicity. At that time, there is increased cotransporter activity, some evidence for increased mRNA for the cotransporter. The cDNA will be sequenced to reveal the primary structure of the cotransporter and facilitate the production of antibodies against it. The antibodies will be used to quantify the number of cotransporters in renal cells in order to determine whether the cells accumulate more myo-inositol because there are more cotransporters, and if there are more, whether that is due to increased synthesis and/or decreased degradation of the cotransporter. The cDNA will be used to construct an RNA probe to measure cell mRNA levels for the cotransporter to determine whether there is in fact an increase in cotransporter mRNA and whether synthesis and/or degradation of the mRNA is regulated. If mRNA synthesis is increased, the gene for the cotransporter will be cloned so that the mechanism of regulation hypertonicity and by other factors can be studied. The cDNA will be used to develop probes to clone the cDNA for sodium/ myo-inositol cotransporters located in the apical plasma membrane of kidney and small intestines where it functions to transport myo-inositol from lumen to blood. The sequence data should yield information about the signal that results in the cotransporter being located in the apical plasma membrane of some epithelia and in the basolateral plasma membrane of other epithelia.