Dopamine inhibition of proximal tubule Na, K-ATPase

多巴胺抑制近曲小管 Na、K-ATP 酶

• 批准号: 6614815
• 负责人: CARLOS H PEDEMONTE
• 金额: $ 31.07万
• 依托单位: UNIVERSITY OF HOUSTON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6614815
• 关键词: biological signal transduction; confocal scanning microscopy; dopamine; electron microscopy; endocytosis; fluorescence resonance energy transfer; genetically modified animals; high performance liquid chromatography; immunoprecipitation; laboratory mouse; matrix assisted laser desorption ionization; phosphatidylinositols; phosphorylation; renal tubule; sodium potassium exchanging ATPase; western blottings

DESCRIPTION (provided by applicant): Renal sodium homeostasis, a major determinant of blood pressure, is regulated by a variety of endocrine, autocrine, and neural factors. The molecular mechanism by which these factors act is not well understood but involves regulation of the rate of tubular sodium reabsorption. Several lines of evidence indicate that regulation of Na+,K+-ATPase activity is, at least in part, responsible for the reduced sodium reabsorption induced by dopamine in renal proximal tubules. At the cellular level, dopamine triggers a specific signaling cascade that ultimately leads to endocytosis of membrane Na+,K+-ATPase, a process that we have demonstrated is responsible for the decreased Na+,K+-ATPase activity. The aims of this proposal are: 1) To determine how the signal originated by phosphorylation of Na+,K+-ATPase alpha-subunit Ser-18 is transmitted to other domains of the a-subunit, such as the polyproline site (81-TPPPTTP-87) and the "endocytic sequence" (537-YLEL). 2) To test the hypothesis that PI3K binds to the Na+,K+-ATPase alpha-subunit polyproline site (81-TPPPTTP-87) and forms a scaffold for recruitment of other proteins that participate in the endocytosis of Na+,K+-ATPase molecules. 3) To identify the location and size of the intracellular pool that exchanges Na+,K+-ATPase molecules with the plasma membrane during dopamine induced Na+,K+-ATPase endocytosis. 4) To identify the stage(s) within the dopamine signaling cascade that is/are sensitive to changes of intracellular sodium concentration. 5) To test the in vivo regulatory role of dopamine by producing transgenic mice that express Na+,K+-ATPase molecules that are resistant to regulation by dopamine. These studies will provide insight into the molecular mechanism by which dopamine promotes renal sodium excretion in proximal tubules. Alterations in the regulation of kidney sodium reabsorption are often found on patients with congestive heart failure, cirrhosis, renal failure, and hypertension. Better knowledge of the mechanism of regulation of proteins involved in renal sodium transport will facilitate the development of new approaches in the treatment of patients with these disorders.

描述(由申请人提供)：肾钠稳态是血压的主要决定因素，受多种内分泌、自分泌和神经因素的调节。这些因素作用的分子机制还不是很清楚，但涉及到管状钠重吸收速率的调节。一些证据表明，对Na+，K+-ATPase活性的调节至少在一定程度上是多巴胺引起的肾脏近端小管钠重吸收减少的原因。在细胞水平上，多巴胺触发特定的信号级联，最终导致膜Na+，K+-ATPase内吞，我们已经证明这一过程是导致Na+，K+-ATPase活性降低的原因。这个建议的目的是：1)确定由Na+，K+-ATPaseα亚基Ser-18磷酸化而来的信号是如何传递到a亚基的其他结构域的，如多聚脯氨酸位点(81-TPPPTTP-87)和“内吞序列”(537-YLEL)。2)验证PI3K与Na+，K+-ATPaseα亚单位多聚脯氨酸结合位点(81-TPPPTTP-87)结合的假说，并为参与Na+，K+-ATPase分子内吞作用的其他蛋白质的募集提供支架。3)确定多巴胺诱导的Na+，K+-ATPase内吞过程中与质膜交换Na+，K+-ATPase分子的胞内池的位置和大小。4)确定多巴胺信号通路中对细胞内钠离子浓度变化敏感的阶段(S)。5)通过制造表达抵抗多巴胺调节的Na+，K+-ATPase分子的转基因小鼠来测试多巴胺在体内的调节作用。这些研究将深入了解多巴胺促进肾近端小管钠排泄的分子机制。充血性心力衰竭、肝硬变、肾功能衰竭和高血压患者常可发现肾脏钠重吸收调节的改变。更好地了解参与肾脏钠转运的蛋白质的调节机制将有助于开发治疗这些疾病患者的新方法。