Gpr116 Regulation of Renal Acid Excretion

Gpr116 肾酸排泄的调节

• 批准号: 10754323
• 负责人: Nathan A Zaidman
• 金额: $ 24.9万
• 依托单位: UNIVERSITY OF NEW MEXICO HEALTH SCIS CTR
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-15 至 2026-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10754323
• 关键词: Acids; Address; Adhesions; Agonist; Alkalosis; Animals; Binding; Biological; Biological Assay; Blood; Cell Separation; Cell membrane; Cre lox recombination system; Data; Disease; Disparate; Drug Targeting; Duct (organ) structure; Electrons; Elements; Endocytosis; Excretory function; Exons; Extracellular Domain; F-Actin; FDA approved; Family; Feedback; Fertility; G-Protein-Coupled Receptors; GTP-Binding Proteins; Glycocalyx; Glycoproteins; Goals; Hormones; Human Genome; Immunity; Immunoprecipitation; In Situ; Integral Membrane Protein; Intercalated Cell; Investigation; Investments; 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; Polymers; 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

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.

项目摘要 G蛋白偶联受体（GPCRs）是一个积分膜蛋白的潜水家族，识别 包括神经递质，激素，光和气味在内的细胞外分子的各种分类。据他们说 是重要的药物靶标，靶向GPCR的1200多种批准的药物。但是，很多 GPCR具有未知的生物学作用。揭示了功能和生理意义 研究的GPCRs代表了许多未开发的治疗潜力。我们的实验室以前报告说 GPR116的粘附级GPCR（AGPCR）是肾脏中表达最高的GPCR之一。 但是，尚未研究其在肾脏生理学中的作用。最近发布的数据 当前的建议证明了GPR116在A中嵌入细胞（AIC）的顶膜中的定位。 鼠收集管道。此外，使用靶向的Cre-lox重组从AIC中删除GPR116 系统显示GPR116是肾脏酸排泄的关键调节剂。小鼠缺乏GPR116 肾脏显着降低尿液pH，并且在诱导A后无法进一步酸化其尿液 代谢性酸中毒，表明GPR116的丧失足以使尿液最大程度地酸化。值得注意的是 通过增加血液pH和PCO2降低，尿液pH的降低是酸/碱的减少 疾病我们称“肾小管碱中毒”。此外，GPR116无效动物的表面明显更多 AIC中V-ATPase质子泵的表达。尽管这些发现很重要，但仍有 关于GPR116在肾脏中的功能的知识，我们的差距很大。例如，分子 在AIC中没有GPR116的情况下引起尿液酸化的机制尚不清楚，并且 接收器的内源激活因子尚未确定。因此，该提议的总体目标 是解决GPR116肾脏生理学的这些关键组成部分。基于以前的观察和 我假设GPR116激活是由本提案中概述的强大初步数据 刺激AIC的微绒毛中膜结合的糖蛋白，导致Rho GTPase级联反应和A 从腔膜中检索V-ATPase。这些支持我的中心假设，即GPR116充当 负反馈元件通过调节V-ATPase内吞作用来抑制过量的酸分泌。我 提出了以下特定目的来检验此假设：1）确定GPR116激活途径 抑制V-ATPase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。这些研究的完成将定义分子途径 首次与肾脏中的GPR116相关，并确定GPR116的治疗潜力 肾酸排泄的靶向调节剂。