CELLULAR REGULATION OF PHOSPHATE TRANSPORT IN KIDNEY

肾脏磷酸盐转运的细胞调节

• 批准号: 3483585
• 负责人: THOMAS P DOUSA
• 金额: $ 15.94万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 1982
• 资助国家: 美国
• 起止时间: 1982-04-01 至 1994-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3483585
• 关键词: alkaline phosphatase; apical membrane; brush border membrane; calcium metabolism; cyclic AMP; dietary potassium; dietary trace element; glucocorticoids; gluconeogenesis; ion transport; kidney metabolism; laboratory mouse; laboratory rabbit; laboratory rat; malnutrition; membrane permeability; membrane transport proteins; nicotinamide adenine dinucleotide; nutrition related tag; parathyroid hormones; phosphates; phosphorus metabolism disorders; posttranslational modifications; protein kinase; renal cortex; renal tubular transport; sodium; vitamin D resistant rickets

The major goal of this research project is to elucidate the cellular mechanisms by which phosphate (Pi) is reabsorbed from the lumen of proximal tubules across the brush border membrane (BBM). The investigations are based on the general hypothesis that: (A). Na+-gradient-dependent uptake of Pi at luminal BBM is of higher capacity in early proximal convoluted tubules (PCT) and is determined mainly by dietary phosphorus (P) intake, whereas in late proximal straight segments - pars recta (PR) it is of lower capacity and is regulated mainly by hormonal stimuli; (B). that long-term "adaptive" stimuli regulate Pi transport across BBM by changing rate or mode of biogenesis of the Na-Pi cotransporter (Na-Pi-COT) of BBM, whereas short-term "rapid" stimuli act by the changing balance between Na-Pi-COT within BBM and Na-P-COT in cytoplasmic depot vesicles - recycling of Na-Pi-COT. Specific objectives of the planned research include: 1). To isolate the BBM vesicles (BBMV) containing Na+-Pi-COT specifically from early proximal segments (PCT) and from the late proximal segments (PR). 2). To determine intramembranous localization of Na-Pi-COT within BBM, and the major biochemical components involved in its function and regulation. 3). To elucidate the biogenesis of the Na-Pi-COT in BBM from PCT and PR. To determine incorporation of amino acid and monosaccharide precursors into Na-P-COT of BBM; these studies will be conducted on renal preparations in vitro and in vivo. 4). To determine the cellular mechanism of action of a) long-term adaptive stimuli (dietary Pi intake, glucocorticoids, thyroxine) and b) rapid modulatory stimuli (PTH, calcitonin, acute Pi load) on biogenesis and recycling of Na-Pi-COT. We will examine whether long-term stimuli modify the rate of synthesis or the mode of post-translational modification of Na-Pi-COT, whereas, rapid stimuli modulate the balance between active Na-Pi-COT inserted into BBM and nonfunctional Na-Pi-COT located in cytoplasmic vesicles (membrane recycling). These regulatory mechanisms will be examined separately in BBM from PCT and BBM from PR. 5). To determine the biochemical nature, intramembranous BBM localization, and axial nephron localization of the Na-Pi-COT defect occurring in the murine model of X-linked hypophosphatemic rickets ("Hyp-mice").

该研究项目的主要目标是阐明细胞 磷酸盐（PI）从近端腔中重吸收的机制 刷子边界膜（BBM）的小管。 调查是 基于：（a）的一般假设。 Na+ - 差异依赖性摄取 Luminal BBM处的PI的能力更高 小管（PCT），主要由饮食磷（P）摄入量确定 而在晚期直段段 - pars retecta（pr）较低 能力，主要由荷尔蒙刺激调节； （b）。长期 “自适应”刺激通过改变速率或 BBM的Na-Pi共转运蛋白（Na-Pi-Cot）的生物发生模式，而 短期“快速”刺激作用着NA-PI-COT之间的平衡不断变化 在BBM和Na-P-COT中，细胞质库囊泡 - 回收 na-pi-cot。 计划研究的具体目标包括： 1）。分离包含Na+-Pi-Cot的BBM囊泡（BBMV） 从早期近端段（PCT）和晚期近端段（PR）。 2）。确定na-pi-cot在BBM中的膜内定位，并 主要的生化成分涉及其功能和调节。 3）。为了阐明来自PCT和PR的BBM中Na-Pi-Cot的生物发生。 确定将氨基酸和单糖前体掺入 BBM的Na-P-COT；这些研究将针对肾脏制剂进行 体内和体内。 4）。确定A）长期自适应的作用机理 刺激（饮食PI摄入，糖皮质激素，甲状腺素）和B）快速 调节性刺激（PTH，降钙素，急性PI负荷）在生物发生和 na-pi-cot的回收。 我们将检查长期刺激是否修改 合成速率或后翻译后修改方式 na-pi-cot，而快速刺激调节主动之间的平衡 Na-pi-cot插入BBM和非功能性Na-Pi-Cot中 细胞质囊泡（膜回收）。 这些调节机制 将从PCT和PR中分别检查BBM和BBM。 5）。为了确定生化性质，膜内BBM定位， 以及发生在Na-Pi-COT缺陷的轴向肾单位定位 X连锁下磷酸ri鼠的鼠模型（“催眠小鼠”）。