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: 10533460
• 负责人: EUGENE P. RHEE
• 金额: $ 48.18万
• 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/10533460
• 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; Pharmacology; 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; alpha-glycerophosphoric acid; base; 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; prevent; renal ischemia; sensor; sodium-phosphate cotransporter proteins; 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.

抽象的 磷酸盐 (Pi) 对生命至关重要，在骨矿化、细胞信号传导和能量方面发挥着重要作用 代谢。然而，如何检测 Pi 水平尚不清楚，这表明在 人类生物学。骨源性激素 FGF23 通过减少肾脏 Pi 重吸收来应对 Pi 升高 和 1,25(OH)2D 的产生，但 Pi 不会直接刺激骨 FGF23 的产生和中间体 Pi 过量和 FGF23 合成之间的步骤仍然不清楚。最近，我们发现了一种肾脏到 骨信号轴，肾源性 3-磷酸甘油 (G-3-P)（糖酵解的副产物）通过该轴循环 进入骨骼并触发 FGF23 的产生。在初步数据中，我们发现 Pi 给药（在喂食的小鼠中）会触发 肾脏中糖酵解和 G-3-P 产生急剧增加，而其他器官没有观察到变化。 在这里，我们提出了一个中心假设：肾近端肾小管细胞糖酵解是哺乳动物的糖酵解过程。 磷酸盐传感器，G-3-P 和 FGF23 的上游。目标 1 将确定糖酵解的作用和 Pi 刺激 G-3-P 生产中的糖异生。我们将检验 Pi 刺激肾脏 G-3-P 的假设 生产发生在进食状态下，但在糖异生条件下减弱；我们将检查两个 生理相关的糖异生刺激、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，Pi 刺激的 G-3-P 需要糖酵解， 糖异生和甘油三酯合成。目标 2 将确定 3-磷酸甘油的作用 脱氢酶 1 (Gpd1) 是一种在全身 Pi 稳态中催化 G-3-P 合成的酶。使用 我们实验室生成了 Gpd1 敲除动物，我们将测试 Gpd1 介导 G-3-P 和 FGF23 的产生对于预防慢性疾病引起的高磷血症、血管钙化和骨质流失是必需的。 膳食Pi负荷；我们将比较 0.6%、1.2% 和 2% Pi 饮食并评估 Gpd1 有或没有的作用 诱发甲状旁腺功能减退症。此外，我们将评估外源性 G-3-P 是否可以拯救有害物质 Gpd1 缺乏对 Pi 稳态的影响。目标 3 将证明钠依赖性协同转运蛋白 Npt2a 赋予糖酵解 Pi 传感的肾脏特异性。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 Npt2a；我们将 在比较静脉注射时还应考虑肠道 Pi 的吸收。与口服 Pi 给药相比。在体外，我们将测试 将 Npt2a 引入没有基础 Npt2a/c 表达的细胞中是否会产生 Pi 响应性糖酵解 和 G-3-P 的产生，如在原代人和小鼠肾近曲小管细胞中观察到的。如果成功的话， 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影响， 并将认可治疗磷酸盐稳态紊乱的新药理学目标。最后，这个 该提案将由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 FGF23、骨生物学和代谢成像。