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Gpr116 Regulation of Renal Acid Excretion

Gpr116 肾酸排泄的调节

基本信息

批准号：
10475269
负责人：
Nathan A Zaidman
金额：
$ 8.72万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-25 至 2022-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10475269
关键词：
Acids Address Adhesions Agonist Alkalosis Animals Biological Biological Assay Blood Cell membrane Consequentialism Cre lox recombination system Data Disease Drug Targeting Duct (organ) structure Electrons Elements Endocytosis Excretory function Exons Extracellular Domain F-Actin FDA approved Family Feedback G-Protein-Coupled Receptors GTP-Binding Protein alpha Subunits, Gs GTP-Binding Proteins Glycocalyx Glycoproteins Goals Hormones Human Immunity Immunoprecipitation In Situ Integral Membrane Protein Intercalated Cell Investigation Kidney Knock-out Knockout Mice Knowledge Life Light Lung Mediating Membrane Metabolic acidosis Molecular Mus N-terminal Neurotransmitters Odors Pathway interactions Peptides Pharmacologic Substance Phase Phylogenetic Analysis Physiological Physiology Platelet Activation Polysaccharides Process Proteins Proton Pump Proton-Translocating ATPases Publishing Pulmonary Surfactants Receptor Activation Recovery Regulation Reporter Reporting Research Research Project Grants Retrieval Role Sequence Homology Signal Transduction Signaling Protein Site Surface Testing Therapeutic Time Tissues Transcript Tubular formation Urine Variant Vesicle apical membrane base biological systems cellular microvillus detection assay experimental study extracellular inhibitor interdisciplinary approach luminal membrane member method development novel polymerization receptor rho rho GTP-Binding Proteins rhotekin synaptic function transcriptome sequencing transmission process tumor progression vacuolar H+-ATPase

项目摘要

Project Summary G protein-coupled receptors (GPCRs) are a diverse family of integral membrane proteins that recognize an assortment of extracellular molecules including neurotransmitters, hormones, light and odors. Accordingly, they are important pharmaceutical targets, with over 1200 FDA approved drugs targeting GPCRs. However, many GPCRs have unknown biologic roles. Thus, uncovering the function and physiologic significance of understudied GPCRs represents a wealth of untapped therapeutic potential. Our lab previously reported that an adhesion-class GPCR (aGPCR), Gpr116, is among the most highly expressed GPCRs in the kidney. However, its role in renal physiology had not been investigated. Recently published data presented in the current proposal demonstrate localization of Gpr116 to the apical membrane of A-intercalated cells (AICs) in murine collecting ducts. Furthermore, deletion of Gpr116 from AICs using a targeted Cre-Lox recombination system revealed Gpr116 to be a critical regulator of renal acid excretion. Mice deficient for Gpr116 in the kidney have significantly reduced urine pH and are incapable of further acidifying their urine after induction of a metabolic acidosis, suggesting that loss of Gpr116 is sufficient to maximally acidify urine. Notably, the reduction in urine pH is accompanied with an increase in blood pH and a decrease in pCO2, an acid/base disorder we term “renal tubular alkalosis”. Moreover, Gpr116-null animals have significantly more surface expression of V-ATPase proton pumps in AICs. Although these findings are significant, there are still substantial gaps in our knowledge regarding the function of Gpr116 in the kidney. For example, the molecular mechanisms that cause urine acidification in the absence of Gpr116 in AICs are unknown, and the endogenous activator of the receptor has yet to be identified. Therefore, the overarching goal of this proposal is to address these critical components of Gpr116 renal physiology. Based on previous observations and strong preliminary data outlined in this proposal, I hypothesize that Gpr116 activation is facilitated by membrane-bound glycoproteins in the microvilli of stimulated AICs, leading to a Rho GTPase cascade and a retrieval of V-ATPase from the luminal membrane. These support my central hypothesis that Gpr116 acts as a negative-feedback element to inhibit excessive acid secretion through regulation of V-ATPase endocytosis. I have proposed the following specific aims to test this hypothesis: 1) Determine the Gpr116-activated pathways that inhibit V-ATPase surface expression; and 2) Identify interactions and luminal conditions that facilitate endogenous activation of Gpr116 in AICs. Completion of these studies will define the molecular pathways relevant to Gpr116 in the kidney for the first time and establish the therapeutic potential of Gpr116 as a targeted modulator of renal acid excretion.

项目概要 G 蛋白偶联受体 (GPCR) 是一个多样化的整合膜蛋白家族，可识别各种细胞外分子，包括神经递质、激素、光和气味。据此，他们是重要的药物靶点，FDA 批准了超过 1200 种针对 GPCR 的药物。然而，许多 GPCR 具有未知的生物学作用。因此，揭示其功能和生理意义未被充分研究的 GPCR 代表着大量尚未开发的治疗潜力。我们实验室之前报道过粘附类 GPCR (aGPCR) Gpr116 是肾脏中表达最高的 GPCR 之一。然而，其在肾脏生理学中的作用尚未得到研究。最近发布的数据显示在目前的提案证明 Gpr116 定位于 A 嵌入细胞 (AIC) 的顶膜小鼠集合管。此外，使用靶向 Cre-Lox 重组从 AIC 中删除 Gpr116 系统显示 Gpr116 是肾酸排泄的关键调节因子。缺乏 Gpr116 的小鼠肾脏显着降低尿液 pH 值，并且在诱导后无法进一步酸化尿液代谢性酸中毒，表明 Gpr116 的损失足以最大限度地酸化尿液。值得注意的是，尿液 pH 值降低伴随着血液 pH 值升高和 pCO2（一种酸/碱）降低这种疾病我们称之为“肾小管性碱中毒”。此外，Gpr116缺失的动物具有明显更多的表面 AIC 中 V-ATPase 质子泵的表达。尽管这些发现意义重大，但仍然存在我们对 Gpr116 在肾脏中的功能的了解存在很大差距。例如，分子 AIC 中缺乏 Gpr116 时导致尿液酸化的机制尚不清楚，并且受体的内源性激活剂尚未确定。因此，本提案的总体目标的目的是解决 Gpr116 肾脏生理学的这些关键组成部分。根据之前的观察和该提案中概述了强有力的初步数据，我假设 Gpr116 的激活是通过刺激 AIC 的微绒毛中的膜结合糖蛋白，导致 Rho GTPase 级联和从管腔膜中回收 V-ATP 酶。这些支持我的中心假设，即 Gpr116 充当负反馈元件通过调节 V-ATP 酶内吞作用抑制过多的酸分泌。我提出了以下具体目标来检验这一假设：1）确定 Gpr116 激活途径抑制 V-ATP 酶表面表达； 2) 确定促进的相互作用和腔内条件 AIC 中 Gpr116 的内源性激活。这些研究的完成将确定分子途径首次与肾脏中的 Gpr116 相关，并确定 Gpr116 作为药物的治疗潜力肾酸排泄的靶向调节剂。