Physiologic regulation of soluble Klotho levels by systemic acid/base status

全身酸/碱状态对可溶性 Klotho 水平的生理调节

基本信息

批准号：
9890373
负责人：
Richard Tyler Miller
金额：
--
依托单位：
VA NORTH TEXAS HEALTH CARE SYSTEM
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9890373
关键词：
Acidosis Acids Adenine Alkalies Alkalinization American Animal Model Atrophic condition of skin Bicarbonates Bilateral Blood Blood Circulation Blood Vessels Calcium-Sensing Receptors Cells Characteristics Chemicals Chronic Chronic Kidney Failure Citrates Clinical Research Clinical Trials Contralateral Cultured Cells DASH diet Dialysis procedure Diet Disease Disease Progression Disease model Distal convoluted renal tubule structure Divalent Cations Early treatment Effectiveness of Interventions End stage renal failure Endothelin Environment Family GTP-Binding Protein alpha Subunits, Gs Goals Health Heart Hypertrophy Human Human Volunteers Hypertension Inflammation Injury to Kidney Ischemia Kidney Kidney Diseases Kidney Failure Knockout Mice Lead Ligands Link Measures Mediating Membrane Microdomains Metabolism Modeling Multiprotein Complexes Mus Nephrectomy Oral Parathyroid gland Pathway interactions Patients Pattern Phenotype Physiological Premature aging syndrome Production Proteins Public Health Rattus Receptor Activation Receptor Signaling Regulation Renal Tissue Renal function Renal tubule structure Renin-Angiotensin-Aldosterone System Reperfusion Therapy Scaffolding Protein Serum Small Interfering RNA Sodium Bicarbonate Source Specificity Structure of renal vein Supplementation System Testing Tissues Transplantation Urine Vascular Diseases Vascular calcification Veterans Work aged alkalinity base calcification coronary fibrosis disease phenotype endothelial dysfunction falls feeding functional loss in vivo kidney fibrosis knock-down loss of function mouse model novel preservation prevent receptor renal calcium response sarcopenia

Acidosis Acids Adenine Alkalies Alkalinization American Animal Model Atrophic condition of skin Bicarbonates Bilateral Blood Blood Circulation Blood Vessels Calcium-Sensing Receptors Cells Characteristics Chemicals Chronic Chronic Kidney Failure Citrates Clinical Research Clinical Trials Contralateral Cultured Cells DASH diet Dialysis procedure Diet Disease Disease Progression Disease model Distal convoluted renal tubule structure Divalent Cations Early treatment Effectiveness of Interventions End stage renal failure Endothelin Environment Family GTP-Binding Protein alpha Subunits, Gs Goals Health Heart Hypertrophy Human Human Volunteers Hypertension Inflammation Injury to Kidney Ischemia Kidney Kidney Diseases Kidney Failure Knockout Mice Lead Ligands Link Measures Mediating Membrane Microdomains Metabolism Modeling Multiprotein Complexes Mus Nephrectomy Oral Parathyroid gland Pathway interactions Patients Pattern Phenotype Physiological Premature aging syndrome Production Proteins Public Health Rattus Receptor Activation Receptor Signaling Regulation Renal Tissue Renal function Renal tubule structure Renin-Angiotensin-Aldosterone System Reperfusion Therapy Scaffolding Protein Serum Small Interfering RNA Sodium Bicarbonate Source Specificity Structure of renal vein Supplementation System Testing Tissues Transplantation Urine Vascular Diseases Vascular calcification Veterans Work aged alkalinity base calcification coronary fibrosis disease phenotype endothelial dysfunction falls feeding functional loss in vivo kidney fibrosis knock-down loss of function mouse model novel preservation prevent receptor renal calcium response sarcopenia

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项目摘要

Chronic kidney disease (CKD) frequently progresses to end-stage renal disease accompanied by complications including cardiac hypertrophy, accelerated vascular disease, ectopic calcification, endothelial dysfunction, osteodystrophy, sarcopenia, skin atrophy, and renal fibrosis. Factors including hypertension, volume-overload, acidosis, chronic low-grade inflammation, disordered Ca and PO4 metabolism, elevated PTH and FGF23 levels, and reduced circulating Klotho (sKlotho) levels are associated with CKD. HCO3 supplementation or alkaline diets (eg. DASH diet) slow progression of CKD even in stages 3 and 4. The mechanism(s) by which HCO3 supplementation or alkaline diets work are unknown. The goal of these studies is to identify physiologic mechanisms that can slow or reverse the course of CKD. sKlotho is normally produced by the kidney and released into the circulation, preserves renal function, and prevents many of the systemic complications of renal failure. As renal disease progresses serum and urine sKlotho levels fall, and patients acquire characteristics resembling the premature aging phenotype of Klotho-/- mice. The kidney is the source of sKlotho as demonstrated by findings that Klotho levels are high in the renal vein, bilateral nephrectomy lowers sKlotho, and mice with kidney-specific Klotho deletion have patterns of disease that are phenotypically indistinguishable from Klotho-/- mice. Possible physiologic mechanisms by which sKlotho levels might be regulated have not been defined. We discovered that in intact mice and rats, mouse renal cortical homogenates, and cultured cells, calcium-sensing receptor (CaSR) activation increases sKlotho levels via ADAM10-mediated shedding. The ability of ligands to activate the CaSR is modified by pH with an alkaline pH environment increasing, and an acid pH environment decreasing CaSR signaling. We found that an alkali load increases CaSR signaling and sKlotho in mice and rats, and that an alkaline milieu increases Klotho shedding in mouse kidney homogenates and cultured cells in a CaSR-dependent manner, and that oral K citrate for 72 hrs increases serum and urine Klotho in human volunteers. These results define a novel physiologic mechanism for regulation of sKlotho levels by the renal CaSR and pH. We hypothesize that acidosis accelerates, and alkalinization slows the rate of loss of renal function in CKD because acidosis decreases, and alkalinity increases renal CaSR-stimulated Klotho shedding from the kidney. The hypothesis will be developed with studies in: 1) mice, CaSR-/- mice, renal homogenates, cultured cells, that will demonstrate that renal Klotho shedding is regulated by the CaSR in response to CaSR ligands and pH; 2) CKD disease models to show that alkali treatment increases sKlotho levels and reduces renal injury and cardiac hypertrophy, and 3) renal tissue and cultured cells to define the mechanisms that permit the CaSR, Klotho, and ADAM10 to interact focusing on the C8 tetraspanin family.

慢性肾脏疾病（CKD）经常发展为并发症完成的终末期肾脏疾病包括心脏肥大，加速血管疾病，异位钙化，内皮功能障碍，骨营养不良，肌肉减少症，皮肤萎缩和肾纤维化。包括高血压，体积超负荷的因素，酸中毒，慢性低度炎症，无序CA和PO4代谢，PTH和FGF23水平升高，循环klotho（Sklotho）水平降低与CKD相关。 HCO3补充或合金即使在第3阶段和第4阶段，饮食（例如DASH饮食）也会缓慢进展。HCO3的机制补充或碱性饮食的工作尚不清楚。这些研究的目的是确定生理可以减慢或逆转CKD过程的机制。 Sklotho通常由肾脏和释放到循环中，保留肾功能，并防止许多肾脏的系统并发症失败。随着肾脏疾病的发展，血清和尿液sklotho水平下降，患者获得了特征类似于klotho的过早衰老表型 - / - 小鼠。肾脏是Sklotho的来源通过发现肾静脉中的klotho水平很高，双侧肾切除术降低了Sklotho，而小鼠则具有肾脏特异性的klotho缺失具有与klotho - / - 表型不同的疾病模式老鼠。尚未定义可能调节Sklotho水平的可能的生理机制。我们发现在完整的小鼠和大鼠中，小鼠肾皮质匀浆和培养的细胞，钙感应受体（CASR）激活通过ADAM10介导的脱落增加了Sklotho水平。配体的能力激活CASR通过pH值增加，合金pH环境增加，酸性pH环境降低CASR信号传导。我们发现，碱负荷增加了小鼠和大鼠的CASR信号传导和Sklotho，而且，酗酒的环境增加了小鼠肾脏匀浆中的klotho脱落 CASR依赖性的方式，口服K柠檬酸盐72小时增加了人类的血清和尿液klotho 志愿者。这些结果定义了一种新型的生理机制，用于通过肾脏调节Sklotho水平 CASR和PH。我们假设酸中毒会加速，碱化减慢了肾脏的损失率 CKD的功能是因为酸中毒的下降，并且碱度增加了肾脏CASR刺激的Klotho 肾脏脱落。该假设将通过：1）小鼠，casr - / - 小鼠，肾脏的研究来开发。匀浆，培养的细胞，这将表明肾脏Klotho脱落受到CASR的调节对CASR配体和pH的反应； 2）CKD疾病模型表明碱处理增加了Sklotho水平并减少肾脏损伤和心脏肥大，以及3）肾脏组织和培养细胞以定义机制这使CASR，Klotho和Adam10可以相互作用，重点是C8四跨果素家族。