Defective flow-dependent tubule transport in the pathogenesis of kidney disease

肾脏疾病发病机制中的血流依赖性肾小管运输缺陷

基本信息

批准号：
10063866
负责人：
Tong Wang Wang
金额：
$ 37.71万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-02-01 至 2022-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10063866
关键词：
Acids Aneurysm Animal Disease Models Apical Architecture Blood Vessels Calcium Cations Cells Cyst Cystic kidney DNA Sequence Alteration Data Defect Development Distal Dopamine Dopamine Antagonists Dopamine Receptor Electrolyte Balance Endocytosis Endoplasmic Reticulum Equilibrium Excretory function Family Feedback Fluid Balance Glomerular Filtration Rate Growth Hydrostatic Pressure Impairment Kidney Kidney Diseases Knockout Mice Liquid substance Measures Mediating Methodology Methods Modeling Mus Mutant Strains Mice Mutation Na(+)-K(+)-Exchanging ATPase Natriuresis Nephrons Null Lymphocytes PKD2 protein Pathogenesis Patients Permeability Phenotype Physiological Play Polycystic Kidney Diseases Potassium Prevention Proton-Translocating ATPases Regulation Renal clearance function Renal tubule structure Role Ryanodine Receptor Calcium Release Channel Signal Transduction Sodium Sodium Chloride Surface TRP channel Testing Tubular formation Variant Work absorption conditional knockout glomerular filtration immunocytochemistry improved in vivo inhibitor/antagonist kidney dysfunction kidney preservation mathematical model mutant mouse model novel novel therapeutics preservation pressure prevent protein intake receptor renal damage shear stress trafficking

项目摘要

Summary The scientific premise of the proposed work is that defective flow-dependent proximal tubule transport may be instrumental in the development and progression of renal dysfunction, a notable example being polycystic kidney disease (PKD). Flow-dependent transport underlies glomerulotubular balance (GTB), whose physiologic importance has been appreciated in normal fluid and electrolyte balance. Whether impaired GTB predisposes to renal damage before GFR is reduced (such as renal cyst formation), has not been studied. Our hypothesis is that episodic increases in kidney tubule hydrostatic pressure promote the creation and growth of renal cysts. This is analogous to the role of arterial pressure in creating vascular aneurysms. There are two control mechanisms, which serve to mitigate the swings in tubule pressure that accompany increases in glomerular filtration (GFR), namely tubuloglomerular feedback and glomerulotubular balance. A mathematical model estimates that with a 50% increase in GFR, impaired GTB increases distal nephron flow, and provokes sharp increases pressure by about 40% in both proximal and distal tubule. This role of GTB, to mitigate GFR- dependent changes of tubule pressure, has never been examined experimentally. During the past 15 years, we have demonstrated that IP3 receptor-mediated intracellular Ca2+ signaling plays a critical role in GTB. Polycystin-2 (PC2) is a nonselective calcium permeable cation channel belonging to the Transient Receptor Potential (TRP) channel family and functions as a Ca2+ channel in the endoplasmic reticulum (ER). Mutations of PC2 abolished the IP3-induced calcium release from the ER. Our preliminary data show a) defective GTB in Pkd2 mutant mice before any renal cysts are formed; and b) Dopamine receptor (DA1) antagonist improves tubule sensitivity to flow and also reduces renal cyst formation in Pkd2 KO mouse, suggesting a new therapeutic method to treat renal disease. In the proposed work, mathematical modeling, renal clearance, microperfusion, immunocytochemistry, and measuring renal tubular pressure in vivo will be used. Hypotheses will be studied in novel nephron-specific conditional knockout PKD animal models, and in PKD null cells to test whether: 1) GTB stabilizes kidney tubule hydrostatic pressure during variations of GFR. This limits tubule distention during GFR elevation, and thus acts to slow cyst formation in Pkd2 KO mice. 2) Inhibition of Na/H- exchanger 3 (NHE3) endocytosis by a DA1 antagonist, increases proximal tubule transporter flow sensitivity, and prevents cyst formation in Pkd2 KO mice. 3) Flow-stimulated NHE3 and/or Na+/K-ATPase trafficking is abrogated in Pkd2 null cells and is similar to blocking the IP3 receptor in WT cells. Inhibition of NHE3 endocytosis by DA1 inhibitor and/or by increasing Ca2+ release from the ER restores the flow-sensing in Pkd2 null cells.

概括拟议工作的科学前提是，有缺陷的流动依赖性近端小管运输可能是在肾功能障碍的发展和进展中发挥了作用，这是一个值得注意的例子是多囊性的肾脏疾病（PKD）。流动依赖的运输是肾小球座平衡（GTB）的基础，其生理在正常的流体和电解质平衡中，重要性已得到理解。 GTB是否易感性障碍在减少GFR之前的肾脏损害（例如肾囊肿形成）尚未研究。我们的假设是肾小管静水压力的情节增加促进了肾囊肿的创造和生长。这类似于动脉压在产生血管动脉瘤中的作用。有两个控制机制，可减轻伴随肾小球增加的小管压力的旋转过滤（GFR），即肾小球斜体反馈和肾小球管平衡。数学模型据估计，随着GFR增加50％，GTB受损会增加肾小管远端流动，并引起尖锐在近端和远端小管中的压力增加了约40％。 GTB的这种角色，以减轻GFR- 小管压力的依赖变化从未通过实验检查。在过去的15年中，我们已经证明IP3受体介导的细胞内Ca2+信号传导在GTB中起关键作用。 Polycystin-2（PC2）是属于瞬态受体的非选择性钙渗透阳离子通道电位（TRP）通道家族和内质网（ER）中的Ca2+通道功能。突变 PC2消除了IP3诱导的钙从ER中释放。我们的初步数据显示a）GTB缺陷在形成任何肾囊肿之前的PKD2突变小鼠； b）多巴胺受体（DA1）拮抗剂改善小管对流动的敏感性，还减少了PKD2 KO小鼠中的肾囊肿形成，这表明了一种新的治疗肾脏疾病的治疗方法。在拟议的工作中，数学建模，肾脏清除率，将使用微灌注，免疫细胞化学和测量体内肾小管压力。假设将在新型的肾单位特异性敲除PKD动物模型和PKD无效细胞中进行研究以测试是否：1）GTB在GFR的变化过程中稳定肾小管静水压力。这限制了小管 GFR升高期间的扩张，因此起作用慢慢的囊肿形成在PKD2 KO小鼠中。 2）抑制Na/h- DA1拮抗剂的交换器3（NHE3）内吞作用，增加了近端小管转运蛋白流动蛋白流动敏感性，并防止PKD2 KO小鼠中的囊肿形成。 3）流量刺激的NHE3和/或Na+/K-ATPase运输是在PKD2无效细胞中废除，类似于阻断WT细胞中的IP3受体。抑制NHE3 DA1抑制剂和/或通过增加Ca2+从ER释放的内吞作用，可恢复PKD2中的流动性零细胞。