Kidney Glycolysis as the Mammalian Phosphate Sensor

肾糖酵解作为哺乳动物磷酸盐传感器

• 批准号: 10705114
• 负责人: EUGENE P. RHEE
• 金额: $ 48.11万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-15 至 2026-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10705114
• 关键词: Acute; Animals; Attenuated; Biochemical; Biology; Blood; Bone Diseases; Cells; Chronic; Collaborations; Coupled; Data; Diet; Disease; Energy Metabolism; Enzymes; Fasting; Gluconeogenesis; Glycerol-3-Phosphate Dehydrogenase; Glycolysis; Goals; Homeostasis; Hormones; Human; Human Biology; Hypoparathyroidism; In Vitro; Intestines; Isotope Labeling; Kidney; Kidney Diseases; Knowledge; Laboratories; Life; Lipids; Magnetic Resonance Imaging; Mediating; Metabolic acidosis; Metabolism; Mus; Nucleic Acids; Oral; Organ; Physiologic calcification; Physiological; Physiology; Play; Positron-Emission Tomography; Process; Production; Proximal Kidney Tubules; Reaction; Role; Signal Transduction; Sodium; Specificity; Stimulus; System; Testing; Tissues; Triglycerides; Tubular formation; Vascular Diseases; Vascular calcification; absorption; alpha-glycerophosphoric acid; body sense; bone; bone health; bone loss; cardiovascular health; dietary; experimental study; fibroblast growth factor 23; fluorodeoxyglucose; follow-up; human disease; in vivo; inhibitor; inorganic phosphate; kidney metabolism; knockout animal; metabolic imaging; metabolomics; novel; pharmacologic; prevent; renal ischemia; sensor; sodium-phosphate cotransporter proteins; symporter; uptake

ABSTRACT Phosphate (Pi) is essential for life, playing fundamental roles in bone mineralization, cell signaling, and energy metabolism. However, how Pi levels are detected is unknown, representing a significant gap in knowledge in human biology. The bone-derived hormone FGF23 responds to elevated Pi by reducing kidney Pi reabsorption and 1,25(OH)2D production, but Pi does not directly stimulate bone FGF23 production and the intermediate steps between Pi excess and FGF23 synthesis have remained obscure. Recently, we identified a kidney-to- bone signaling axis whereby kidney-derived glycerol-3-phosphate (G-3-P), a byproduct of glycolysis, circulates to bone and triggers FGF23 production. In preliminary data, we find that Pi administration (in fed mice) triggers an acute increase in glycolysis and G-3-P production in the kidney, with no change observed in other organs. Here, we advance the central hypothesis that kidney proximal tubular cell glycolysis is the mammalian phosphate sensor, upstream of G-3-P and FGF23. Aim 1 will determine the role of glycolysis and gluconeogenesis in Pi-stimulated G-3-P production. We will test the hypothesis that Pi-stimulated kidney G-3-P production occurs in the fed state, but is attenuated under gluconeogenic conditions; we will examine two physiologically relevant gluconeogenic stimuli, fasting and metabolic acidosis. In addition, we will show that glycolysis is required for Pi-stimulated G-3-P using isotope labeling and inhibitors of glycolysis, gluconeogenesis, and triglyceride synthesis. Aim 2 will establish the role of glycerol-3-phosphate dehydrogenase 1 (Gpd1), the enzyme that catalyzes G-3-P synthesis, in systemic Pi homeostasis. Using a Gpd1 knockout animal generated in our laboratory, we will test the hypothesis that Gpd1 mediated G-3-P and FGF23 production is required to prevent hyperphosphatemia, vascular calcification, and bone loss with chronic dietary Pi loading; we will compare 0.6%, 1.2%, and 2% Pi diets and assess the role of Gpd1 with or without induced hypoparathyroidism. Further, we will assess whether exogenous G-3-P can rescue the deleterious effects of Gpd1 deficiency on Pi homeostasis. Aim 3 will demonstrate that the sodium-dependent cotransporter Npt2a confers kidney specificity to glycolytic Pi sensing. We will test the hypothesis that Pi-stimulated glycolysis in the kidney requires Npt2a, as assessed by 18F-FDG PET/MRI and metabolomic profiling; we will also consider intestinal Pi uptake in a comparison of i.v. versus oral Pi administration. In vitro, we will test whether the introduction of Npt2a to cells without basal Npt2a/c expression confers Pi-responsive glycolysis and G-3-P production, as observed in primary human and mouse kidney proximal tubule cells. If successful, these studies will identify a new mammalian sensor, with broad implications for human biology and disease, and will endorse new pharmacologic targets for treating disorders of phosphate homeostasis. Finally, this proposal will be executed by a team with a track record of collaboration, spanning expertise in kidney metabolism, Pi and FGF23, bone biology, and metabolic imaging.

摘要 磷酸盐（Pi）是生命所必需的，在骨矿化、细胞信号和能量中起着重要作用 新陈代谢.然而，如何检测Pi水平是未知的，这代表了在知识上的显著差距。 人类生物学骨源性激素FGF 23通过减少肾脏对Pi的重吸收来响应Pi的升高 和1，25（OH）2D的产生，但Pi不直接刺激骨FGF 23的产生， Pi过量和FGF 23合成之间的步骤仍然不清楚。最近，我们发现了一个肾脏- 骨信号传导轴，来自肾脏的甘油-3-磷酸（G-3-P），糖酵解的副产物，在其中循环 并触发FGF 23的产生。在初步数据中，我们发现Pi给药（在喂养的小鼠中）触发了 肾脏中糖酵解和G-3-P产生的急性增加，在其他器官中未观察到变化。 在这里，我们提出的中心假设，肾近端小管细胞糖酵解是哺乳动物 磷酸盐传感器，G-3-P和FGF 23的上游。目标1将确定糖酵解的作用， 在Pi刺激的G-3-P产生中的异源发生。我们将检验Pi刺激肾脏G-3-P 生产发生在进食状态，但在产气条件下减弱;我们将研究两个 生理学相关的致炎性刺激、禁食和代谢性酸中毒。此外，我们将证明， 使用同位素标记和糖酵解抑制剂的Pi刺激的G-3-P需要糖酵解， 异源生成和甘油三酯合成。目标2将确定甘油-3-磷酸的作用 脱氢酶1（Gpd 1），催化G-3-P合成的酶，在系统性Pi稳态中起重要作用。使用 Gpd 1基因敲除的动物，我们将检验Gpd 1介导G-3-P和 需要FGF 23的产生来预防高磷酸盐血症、血管钙化和慢性骨质疏松症的骨丢失。 饮食Pi负荷;我们将比较0.6%，1.2%和2% Pi饮食，并评估Gpd 1的作用， 诱发甲状旁腺功能减退此外，我们将评估外源性G-3-P是否可以拯救有害的 Gpd 1缺乏对Pi稳态的影响。目的3将证明钠依赖性协同转运蛋白 Npt 2a赋予肾对糖酵解Pi传感的特异性。我们将检验Pi刺激的假设 通过18F-FDG PET/MRI和代谢组学分析评估，肾脏中的糖酵解需要Npt 2a; 在静脉内与口服Pi给药的比较中也考虑了肠道Pi摄取。在体外，我们将测试 将Npt 2a引入没有基础Npt 2a/c表达的细胞是否赋予Pi响应性糖酵解 和G-3-P产生，如在原代人和小鼠肾近端小管细胞中观察到的。如果成功， 这些研究将确定一种新的哺乳动物传感器，对人类生物学和疾病具有广泛的意义， 并将为治疗磷酸盐体内平衡紊乱提供新的药理学靶点。最后 该提案将由一个具有合作记录的团队执行，涵盖肾脏领域的专业知识 代谢、Pi和FGF 23、骨生物学和代谢成像。