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Regulation of renal ion transport by the CUL3-WNK-SPAK pathway

CUL3-WNK-SPAK 通路对肾离子转运的调节

基本信息

批准号：
10083727
负责人：
JAMES A MCCORMICK
金额：
$ 33.88万
依托单位：
OREGON HEALTH & SCIENCE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-04-01 至 2023-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10083727
关键词：
Address Affect Amino Acids Animals Autophagocytosis Binding Blood Pressure Cardiac Myocytes Cells Chronic Kidney Failure Complex Cullin Proteins Cultured Cells Data Defect Development Dietary Potassium Disease Disputes Distal Distal convoluted renal tubule structure Equilibrium Exons Familial disease Functional disorder Gitelman syndrome Goals Heart failure Heterozygote Homeostasis Human Hypertension Hypokalemia Immunofluorescence Immunologic In Vitro Ion Transport Kidney Knock-out Knockout Mice Knowledge Lead Ligase Limb structure Maintenance Mediating Messenger RNA Modeling Molecular Mus Mutation Nephrons Neurons Normal Range Pathway interactions Phenotype Phosphotransferases Physiology Plasma Play Polyuria Potassium Primary Cell Cultures Progress Reports Proteins Rare Diseases Regulation Role SLC11A2 gene Scaffolding Protein Skeletal Muscle Sodium System Testing Thick Ubiquitination Work base blood pressure regulation cullin-3 driving force exon skipping extracellular familial hyperkalemic hypertension gain of function hyperkalemia in vivo inhibitor/antagonist insight loss of function meter mouse model mutant novel therapeutics renal epithelium scaffold sensor ubiquitin ligase

项目摘要

Project Summary The kidney plays a key role in maintaining plasma [K+], with distal segments of the nephron fine-tuning K+ secretion to keep it in the normal range. We previously proposed that the renal distal convoluted tubule (DCT) plays a key role by sensing plasma [K+]. Decreasing plasma [K+] by dietary K+ restriction activates the WNK- SPAK/OSR1-NCC pathway, and increased NaCl reabsorption though NCC reduces delivery of sodium to, and possibly remodels, distal K+ secreting segments to lower K+ secretion. The disease Familial Hyperkalemic Hypertension (FHHt) is caused by increased NCC activation due to mutations in WNKs, Cullin 3 (CUL3), and KLHL3. The Cullin Ring Ligase (CRL) complex, composed of the scaffold CUL3, the substrate adaptor KLHL3, and the ligase RING, degrades WNKs. The effects of mutant CUL3, produced by skipping of exon 9 which causes internal deletion of 57 amino acids (CUL3-∆9), are controversial. CUL3-∆9 triggers its own degradation in vitro, and also in a mouse model of CUL3 FHHt. Thus, the prevailing model is that CUL3-∆9 causes FHHt by inducing CUL3 haploinsufficiency. Our preliminary data in CUL3 heterozygote mice and a new mouse model of CUL3-∆9 FHHt do not support this, and we hypothesize that CUL3-∆9 exerts dominant effects to cause FHHt and dysregulate the plasma [K+] sensor. We propose that CUL3-∆9 causes FHHt by a combined effect of lowering abundance of itself and of KLHL3. Our data suggest that NKCC2 activation along the thick ascending limb (TAL) may also contribute to FHHt. Finally, we previously generated kidney-specific CUL3 knockout (KO) mice, and found that they display a severe phenotype (polyuria and chronic kidney disease), with defects along multiple nephron segments. Our overall aim is to determine the mechanisms underlying CUL3-∆9-mediated FHHt, and gain insight into CUL3 function in the kidney. In Aim 1 we will determine the effects of CUL3-∆9 expression and CUL3 KO specifically along DCT to determine whether CRL disruption along DCT is sufficient to cause FHHt. We will determine the effects of CRL disruption on KLHL3 in mice, since we found CUL3-∆9 inappropriately degrades it in cultured cells. We will also directly test whether mice with lower abundance of CUL3 and KLHL3 develop FHHt. In Aim 2 we will determine whether remodeling of K+-secreting segments occurs in FHHt mediated by CUL3-∆9, and examine the effects of CRL disruption on NKCC2 activity. Some models suggest that CUL3-∆9 leads to dramatically lower CRL activity, but data suggest this would be lethal. We propose that CUL3-∆9 may exert unique effects that cause it to preferentially degrade certain CRL adaptors. Therefore, in Aim 3 we will examine effects of CUL3-∆9 on other CRL adaptors and substrates in our mouse models and in primary cell culture.

项目总结