Role of Ion Channels in Kidney Diseases

离子通道在肾脏疾病中的作用

• 批准号: 8932680
• 负责人: HE-PING MA
• 金额: $ 35.1万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-24 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8932680
• 关键词: ATP-Binding Cassette Transporters; Address; Affect; Angiotensin II; Apical; Atomic Force Microscopy; Binding; Blood Pressure; Cell membrane; Cells; Cholesterol; Cholesterol Homeostasis; Cholesterol Synthesis Inhibition; Clinical Research; Confocal Microscopy; Data; Development; Diffusion; Distal; Down-Regulation; Duct (organ) structure; Electron Microscopy; Epithelial; Equilibrium; Genetic Polymorphism; Goals; Health; Hypertension; In Vitro; Intracellular Membranes; Investigation; Ion Channel; Kidney; Kidney Diseases; Knock-out; Knockout Mice; Lateral; Lovastatin; Membrane; Membrane Lipids; Metabolic; Methods; Movement; Mus; Nephrons; Patch-Clamp Techniques; Pathway interactions; Phosphatidylinositol 4,5-Diphosphate; Phosphoric Monoester Hydrolases; Phosphotransferases; Regulation; Reporting; Resolution; Role; Scanning; Sodium; Sodium Channel; System; Tangier Disease; Telemetry; Testing; absorption; apical membrane; base; cellular microvillus; cholesterol biosynthesis; cholesterol transporters; cholesterol-binding protein; clinically significant; epithelial Na+ channel; in vivo; inhibitor/antagonist; innovation; loss of function mutation; mouse model; novel; patch clamp; phosphatidylinositol 4-phosphate; prominin; receptor; research study; salt intake; scanning ion conductance microscopy

DESCRIPTION (provided by applicant): The long term goals of this project are to determine the regulation of ion channels in the kidney and to integrate our findings to kidney diseases. This proposal will determine how the renal epithelial sodium channel (ENaC) is regulated by ATP-binding cassette transporter A1 (ABCA1). The proposed in vivo and in vitro experiments will test a central hypothesis that deletion of ABCA1 elevates Cho in cortical collecting duct (CCD) principal cells, this elevated Cho stabilizes phosphatidylinositol-4,5-bisphosphate (PIP2) in apical microvilli, and this microvilli- located PIP2 increases ENaC activity to enhance sodium retention and cause hypertension. The hypothesis is based on previous studies and two key preliminary data showing that both blood pressure and ENaC activity are elevated in ABCA1 KO mice and that inhibition of Cho synthesis causes PIP2 diffusion out of microvilli and reduces ENaC activity. The proposal is clinically significant, because investigation of ABCA1-controlled membrane and intracellular Cho homeostasis may provide a rationale for using Cho biosynthesis inhibitors such as statins to treat hypertension. The project is innovative because it will provide the first evidence for the role of ABCA1 in regulating ENaC activity and PIP2 lateral movement between two specialized apical membrane domains (microvilli and planar regions). A variety of experimental approaches including scanning ion conductance microscopy and the high resolution scanning patch-clamp techniques will be used to test three hypotheses (1) that deletion of ABCA1 increases ENaC activity and Na+ absorption thereby causing hypertension; (2) that Cho increases ENaC activity by stabilizing PIP2 in microvilli; and (3) that PIP2 in planar regions promotes formation of endocytic pits containing inactive ENaC.

描述（由申请人提供）：该项目的长期目标是确定肾脏中离子通道的调节并将我们的发现整合到肾脏疾病中。该提案将确定 ATP 结合盒转运蛋白 A1 (ABCA1) 如何调节肾上皮钠通道 (ENaC)。拟议的体内和体外实验将测试一个中心假设，即 ABCA1 的缺失会升高皮质集合管 (CCD) 主细胞中的 Cho，这种升高的 Cho 会稳定顶端微绒毛中的磷脂酰肌醇 4,5-二磷酸 (PIP2)，并且这种微绒毛- 定位的 PIP2 会增加 ENaC 活性，从而增强钠潴留并导致高血压。该假设基于之前的研究和两个关键的初步数据，这些数据表明 ABCA1 KO 小鼠的血压和 ENaC 活性均升高，并且抑制 Cho 合成会导致 PIP2 扩散出微绒毛并降低 ENaC 活性。该提议具有临床意义，因为对 ABCA1 控制的细胞膜和细胞内 Cho 稳态的研究可能为使用他汀类药物等 Cho 生物合成抑制剂治疗高血压提供依据。该项目具有创新性，因为它 将为 ABCA1 在调节 ENaC 活性和两个特殊顶膜区域（微绒毛和平面区域）之间的 PIP2 横向运动中的作用提供第一个证据。包括扫描离子电导显微镜和高分辨率扫描膜片钳技术在内的多种实验方法将用于测试三个假设（1）ABCA1 的缺失增加 ENaC 活性和 Na+ 吸收，从而导致高血压； (2) Cho通过稳定微绒毛中的PIP2来增加ENaC活性； (3) 平面中的 PIP2 区域促进含有非活性 ENaC 的内吞凹坑的形成。