NaCI Balance and Targeted Insulin Receptor Knockout Mice

NaCI 平衡和靶向胰岛素受体基因敲除小鼠

• 批准号: 6762353
• 负责人: Carolyn Mary Ecelbarger
• 金额: $ 15.52万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6762353
• 关键词: animal breeding; electrolyte balance; gene targeting; genetically modified animals; hyperinsulinism; hypertension; insulin receptor; insulin sensitivity /resistance; laboratory mouse; nutrition related tag; pathogenic diet; renal tubular transport; saluresis; sodium chloride; tissue /cell culture; transport proteins

DESCRIPTION (provided by applicant): Insulin is an anti-natriuretic hormone in the kidney. Insulin increases sodium reabsorption in the proximal tubule, thick ascending limb, and distal tubule. However, the molecular mechanisms underlying its actions are not well described. In addition, hyperinsulinemia, due to insulin resistance, is highly correlated with hypertension, which often precedes chronic renal disease. Nevertheless, because of the complexity of these pathological states, the direct effects of insulin, in the kidney through its own receptor, are difficult to parse out. Thus, these studies are aimed at developing two new animal models that will allow us to better address the direct role of insulin in the kidney and its role in NaCI balance, blood pressure, and the regulation of renal NaCI transport proteins. In order to achieve these aims our plan is to develop, through breeding, using the CRE/IoxP approach, two lines of transgenic mice in which the insulin receptor (IR) is knocked out of either the collecting duct principal cells or the thick ascending limb cells, respectively. These mice (and cell cultures prepared from their kidneys) will be evaluated for insulin-sensitive NaCI transport, blood pressure changes, and the regulation of target transport proteins. In this proposal, we test the overall hypothesis that mice that lack insulin receptors in either their collecting duct principal or thick ascending limb cells due to selective knock out of gene expression in these cells will have decreased NaCI reabsorption at these sites under basal or stimulated conditions. In specific aim 1, we plan to develop the collecting duct principal cell insulin receptor knock-out mouse (CD-IR KO) and evaluate NaCI transporting characteristics under basal conditions. In specific aim 2, we plan to develop the thick ascending limb cell insulin receptor knock-out mouse (TAL-IR KO) and, likewise, evaluate basal NaCI transport. Finally, in specific aim 3, we plan to evaluate blood pressure, NaCI balance, NaCI transport, and the regulation of renal NaCI transport proteins in the above mice under hyperinsulinemic conditions in vivo and ex vivo. We plan to achieve hyperinsulinemia in the mouse in two ways: 1) we will infuse insulin via the jugular vein; and 2) we will feed a diabetogenic diet that should induce insulin resistance and thus raise endogenous insulin levels. Overall, we believe these models will provide fresh molecular insight into a physiological phenomenon that has been known for decades, insulin induced hypertension, with clear clinical ramifications.

描述（由申请人提供）：胰岛素是肾脏中的一种抗利钠激素。 胰岛素增加近端肾小管、升支粗管和远端肾小管的钠重吸收。 然而，其作用背后的分子机制尚未得到很好的描述。 此外，由于胰岛素抵抗而导致的高胰岛素血症与高血压高度相关，而高血压通常先于慢性肾病发生。 然而，由于这些病理状态的复杂性，胰岛素通过其自身受体在肾脏中的直接作用很难解析。 因此，这些研究旨在开发两种新的动物模型，使我们能够更好地解决胰岛素在肾脏中的直接作用及其在氯化钠平衡、血压和肾脏氯化钠转运蛋白调节中的作用。 为了实现这些目标，我们的计划是使用 CRE/IoxP 方法通过育种开发两个转基因小鼠品系，其中集合管主细胞或粗升肢细胞中的胰岛素受体 (IR) 被敲除细胞，分别。 将评估这些小鼠（以及从其肾脏制备的细胞培养物）的胰岛素敏感性 NaCl 转运、血压变化和靶转运蛋白的调节。 在本提案中，我们测试了总体假设，即由于选择性敲除这些细胞中的基因表达而在集合管主细胞或厚升肢细胞中缺乏胰岛素受体的小鼠在基础或刺激条件下将在这些部位减少 NaCl 重吸收。 在具体目标1中，我们计划开发集合管主细胞胰岛素受体敲除小鼠（CD-IR KO）并评估基础条件下的NaCI转运特性。 在具体目标 2 中，我们计划开发厚升肢细胞胰岛素受体敲除小鼠 (TAL-IR KO)，并同样评估基础 NaCl 转运。 最后，在具体目标3中，我们计划在体内和离体高胰岛素条件下评估上述小鼠的血压、氯化钠平衡、氯化钠转运和肾氯化钠转运蛋白的调节。 我们计划通过两种方式在小鼠中实现高胰岛素血症：1）通过颈静脉注射胰岛素； 2）我们将喂食致糖尿病的饮食，这会引起胰岛素抵抗，从而提高内源性胰岛素水平。 总的来说，我们相信这些模型将为几十年来已知的生理现象（胰岛素诱发的高血压）提供新的分子见解，并具有明确的临床影响。