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.

抽象的 磷酸盐（PI）对于生命至关重要，在骨矿化，细胞信号和能量中发挥基本作用 代谢。但是，如何检测PI级别是未知的，代表了知识的显着差距 人类生物学。骨衍生的激素FGF23通过减少肾脏PI的重吸收来响应PI的升高 和1,25（OH）2D生产，但PI并未直接刺激骨FGF23的产生和中间。 PI过量和FGF23合成之间的步骤仍然晦涩难懂。最近，我们确定了肾脏至 骨信号轴，肾脏衍生的甘油-3-磷酸甘油（G-3-P），糖酵解的副产品，循环 骨骼和触发FGF23产生。在初步数据中，我们发现PI给药（在喂养小鼠中）触发 肾脏中糖酵解和G-3-P产生的急性增加，在其他器官中没有观察到的变化。 在这里，我们推进了肾脏近端管细胞糖酵解是哺乳动物的中心假设 磷酸盐传感器，G-3-P和FGF23的上游。 AIM 1将决定糖酵解的作用和 PI刺激的G-3-P产生中的糖异生。我们将测试PI刺激的肾脏G-3-P的假设 生产发生在美联储状态，但在糖原性条件下会减弱。我们将检查两个 生理上相关的糖原性刺激，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的抑制剂，需要糖酵解PI刺激的G-3-P， 糖异生和甘油三酸酯合成。 AIM 2将确定3-磷酸甘油的作用 脱氢酶1（GPD1），催化G-3-P合成的酶，在全身性PI稳态中。使用 GPD1敲除动物在我们的实验室产生的动物，我们将检验以下假设：GPD1介导的G-3-P和 需要产生FGF23以防止高磷酸血症，血管钙化和骨质流失 饮食PI负载；我们将比较0.6％，1.2％和2％PI饮食，并评估GPD1的作用。 诱发甲状腺功能减退症。此外，我们将评估外源G-3-P是否可以挽救有害的 GPD1缺乏对PI稳态的影响。 AIM 3将证明依赖钠的共转运蛋白 NPT2A赋予肾脏特异性对糖酵解PI感应。我们将测试PI刺激的假设 肾脏中的糖酵解需要NPT2a，如18F-FDG PET/MRI和代谢组分析所评估的。我们将 还考虑在静脉内的肠道摄入量与口服PI给药。在体外，我们将测试 将NPT2A引入没有基础NPT2A/C表达的细胞是否赋予PI反应性糖酵解 如在原代人和小鼠肾近端小管细胞中观察到的，G-3-P产生。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影响， 并将认可治疗磷酸盐稳态疾病的新药理靶标。最后，这个 提案将由具有协作记录的团队执行，涵盖肾脏的专业知识 代谢，PI和FGF23，骨生物学和代谢成像。