Interplay of Renal Ca and Na Transport Pathways

肾钙和钠转运途径的相互作用

• 批准号: 7362397
• 负责人: JI-BIN PENG
• 金额: $ 26.22万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7362397
• 关键词: Adult; Affect; Anabolism; Apical; Binding; Binding Sites; Biochemical; Blood Pressure; Calmodulin; Carrier Proteins; Cell Line; Cell membrane; Cells; Dietary Intervention; Disease; Distal; Distal convoluted renal tubule structure; Dose; Elderly; Employee Strikes; Epithelial; Equilibrium; Figs - dietary; Gatekeeping; Goals; Health; Heart failure; Hereditary Disease; Hypertension; Hypotension; Ions; Kidney; Knowledge; Link; Localized; Mediating; Molecular; Myocardial Infarction; Numbers; Oocytes; Osteoporosis; Pathogenesis; Pathway interactions; Phosphotransferases; Physiological; Plasma; Play; Positioning Attribute; Protein Kinase; Regulation; Research; Research Personnel; Risk Factors; Role; Side; Stroke; Surface; Syndrome; System; Testing; Tetanus Helper Peptide; Work; Xenopus laevis; apical membrane; base; blood pressure regulation; expectation; experience; innovation; insight; mutant; novel strategies; pressure; prevent; programs; radiotracer; thiazide; trafficking; voltage

DESCRIPTION (provided by applicant): Hypertension occurs in nearly one out of every three US adults and is a major risk factor for stroke, heart attack, and heart failure. The molecular pathogenesis of hypertension is not well understood; however, recent findings from genetic disorders affecting blood pressure highlight the important roles of the thiazide- sensitive Na-CI cotransporter NCC and the WNK protein kinases in the distal tubule of the kidney in blood pressure regulation. Intriguingly, Na and Ca transport pathways in the distal tubule are inversely related; therefore, an increase in Ca transport in the distal tubule decreases the Na transport and in turn lowers the blood pressure. Hence, a detailed understanding of the interplay between the Na and Ca transport pathways is important in blood pressure regulation. As a gatekeeper for Ca reabsorption, TRPV5 is prominently localized in the apical membrane of the late segment of the distal convoluted tubule, where NCC and WNK4 are also expressed. WNK4 enhances TRPVS-mediated Ca transport in striking contrast to its inhibitory effect on NCC. Furthermore, the enhancing effect of WNK4 on TRPV5 is dose-dependently blocked by NCC. In addition, the enhancing effect of WNK4 on TRPV5 is abolished by chelating intracellular Ca. Based on these findings we hypothesize that WNK4 integrally regulates Na and Ca transport pathways by enhancing TRPV5 and suppressing NCC; the actions of WNK4 are also modulated by TRPV5 and NCC. We plan to test our hypothesis by pursuing three specific aims: 1) determine the mechanism by which WNK4 enhances TRPVS-mediated Ca transport; 2) determine the mechanism by which NCC modulates the action of WNK4; and 3) determine the role of Ca/calmodulin in modulating WNK4-mediated regulation. The studies will be carried out using molecular, biochemical and physiological approaches with both X. laevis oocytes and MDCK strain I cells. Stable MDCK I cell lines will be developed to assess the physiological significance of the regulation mechanisms. It is expected that new insights into the regulation of Ca and Na transport pathways through the interplay between the transport proteins and their common regulator WNK4 will be obtained at the completion of the project. With new knowledge acquired from the proposed studies, it is likely a new strategy via integral regulation of Na and Ca pathways in the distal tubule could be developed for blood pressure control.

描述（由申请人提供）：近三分之一的美国成年人患有高血压，是中风、心脏病和心力衰竭的主要危险因素。高血压的分子发病机制尚不清楚；然而，最近对影响血压的遗传性疾病的研究结果强调了噻嗪类敏感性 Na-CI 协同转运蛋白 NCC 和肾远端小管中的 WNK 蛋白激酶在血压调节中的重要作用。有趣的是，远端小管中的 Na 和 Ca 转运途径呈负相关。因此，远端肾小管中钙转运的增加会减少钠转运，从而降低血压。因此，详细了解钠和钙转运途径之间的相互作用对于血压调节非常重要。作为 Ca 重吸收的看门人，TRPV5 显着定位于远曲小管后段的顶膜，NCC 和 WNK4 也在此表达。 WNK4 增强 TRPVS 介导的 Ca 转运，与其对 NCC 的抑制作用形成鲜明对比。此外，WNK4 对 TRPV5 的增强作用被 NCC 剂量依赖性地阻断。此外，WNK4对TRPV5的增强作用被细胞内Ca螯合所消除。基于这些发现，我们假设 WNK4 通过增强 TRPV5 和抑制 NCC 来整体调节 Na 和 Ca 转运途径。 WNK4 的作用也受到 TRPV5 和 NCC 的调节。我们计划通过追求三个具体目标来检验我们的假设：1）确定 WNK4 增强 TRPVS 介导的 Ca 转运的机制； 2)确定NCC调节WNK4作用的机制； 3)确定Ca/钙调蛋白在调节WNK4介导的调节中的作用。这些研究将采用分子、生物化学和生理学方法，对非洲虎卵母细胞和 MDCK I 株细胞进行。将开发稳定的 MDCK I 细胞系来评估调节机制的生理意义。预计在该项目完成后，将获得通过转运蛋白与其共同调节因子 WNK4 之间的相互作用来调节 Ca 和 Na 转运途径的新见解。利用从拟议研究中获得的新知识，很可能可以开发出一种通过远端小管中 Na 和 Ca 途径的整体调节来控制血压的新策略。