CELLULAR MECHANISMS OF MINERALOCORTICOID ACTION

描述（改编自申请人的摘要）： 细胞外液容量稳态对于血流动力学是必不可少的 稳定性和肾钠处理异常与 心血管疾病和高血压。 钠的最终调节 肾脏中的排泄发生在远端肾单位中， 盐皮质激素醛固酮 这项研究的长期目标是 了解醛固酮调节钠的细胞机制 重吸收 醛固酮作用的初始生理事件是 由于数量的增加， 传导性钠通道的开放概率。 本研究建议， 研究这种通道激活的生化机制。 已知蛋白质的羧甲基化受醛固酮刺激， 确切的地点仍有争议。 这项研究将表征醛固酮 钠通道特定亚基的依赖性羧甲基化， 采用体外缺失和定点突变技术， 转录的肽以确定门控的特定位点 羧甲基化 这些实验将通过重构来验证 在脂质双层中的研究，以验证 甲基化位点 甲基转移酶的调控研究 将其具体的基板进行，以确定性质的 醛固酮调节步骤。 由于通道子单元是明显的最终 醛固酮调节的效应物或底物，将进行研究 确定醛固酮调节的时间过程和性质， 在顶端膜的亚基组成。 最后，研究将 开始检查盐皮质激素的转录激活 和糖皮质激素在受体移位、转运 激活和生化目标。

DESCRIPTION (Adapted from the Applicant's Abstract): Maintenance of extracellular fluid volume homeostasis is essential for hemodynamic stability, and abnormalities of renal sodium handling have been linked to cardiovascular disease and hypertension. Ultimate regulation of sodium excretion in the kidney occurs in the distal nephron and is modulated by the mineralocorticoid aldosterone. The long-term goal of this research are to understand the cellular mechanisms by which aldosterone regulates sodium reabsorption. The initial physiologic event in aldosterone action is an increase in apical membrane permeability due to an increase in number and open probability of conductive sodium channels. This study proposes to study the biochemical mechanisms underlying this channel activation. Carboxymethylation of proteins is known to be stimulated by aldosterone but the exact site is in dispute. This study will characterize the aldosterone dependent carboxymethylation of specific subunits of the sodium channel and employ the techniques of deletion and site specific mutagenesis of in vitro transcribed peptides to determine the specific site of the gating carboxymethylation. These experiments will be paralleled by reconstitution studies in lipid bilayers to validate the physiologic relevance of the methylation site. Studies of the regulation of the methyltransferase and its specific substrate will be carried out to determine the nature of the aldosterone regulated step. Since channel subunits are apparent final effector or substrate for aldosterone regulation, studies will be carried out to define the time course and nature of aldosterone regulation of subunit composition in the apical membrane. Finally, studies will be initiated to examine the transcriptional activation by mineralocorticoids and glucocorticoids both in terms of receptor translocation, transport activation and biochemical targets.