Regulation of Renal Bicarbonate and Chloride Absorption

肾脏碳酸氢盐和氯化物吸收的调节

• 批准号: 7463901
• 负责人: ROBERT J ALPERN
• 金额: $ 37.98万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7463901
• 关键词: Acidosis; Acids; Acute; Adenylate Cyclase; Aldolase B; Alkalies; Amino Acid Sequence; Amino Acids; Ammonia; Bicarbonates; Binding; Binding Proteins; Blood; Buffers; C-terminal; Cell-Free System; Cells; Chimera organism; Chloride Ion; Chlorides; Chronic; Circadian Rhythms; Citrate; Citrates; Endothelin; Endothelin B Receptor; Endothelin-1; Enzymes; Focal Adhesions; Genes; Goals; Grant; Interstitial Nephritis; Kidney; Laboratories; Laboratory Study; Mediating; Messenger RNA; Metabolic acidosis; Microarray Analysis; Molecular; Mus; Muscle; Muscle Proteins; Mutagenesis; Nephrocalcinosis; Nephrolithiasis; Normal Range; Numbers; Osteoclasts; Osteoporosis; Phosphotransferases; Play; Process; Protein Binding; Protein Tyrosine Kinase; Proteins; Protons; Proximal Kidney Tubules; Receptor Activation; Regulation; Role; Role playing therapy; SRC gene; Series; Signal Pathway; Signal Transduction; System; Tail; Transfection; Tubular formation; Tyrosine Phosphorylation; Yeasts; absorption; antiporter; apical membrane; base; bone; design; hypercalciuria; kidney cortex; mutant; nocturnin; novel; receptor; research study; response; sensor; yeast two hybrid system

DESCRIPTION (provided by applicant): Chronic metabolic acidosis induces a series of homeostatic responses that are designed to return blood pH to normal values. In the renal proximal tubule, this response includes increases in hydrogen ion secretion, ammonia synthesis and citrate absorption. Studies from this laboratory have examined the molecular basis by which these adaptations occur, focusing on regulation of the apical membrane Na/H antiporter, NHE3. During the last grant period, we showed that significant roles are played by the endothelins, Pyk2, c-Src, ERK, and focal adhesion proteins. The proposed studies continue our focus on the mechanisms by which the proximal tubule senses a decrease in intracellular pH and relays the signals so as to eventually increase NHE3 activity. Studies are divided into four aims. In aim 1, studies will utilize microarrays to identify novel acid-regulated and endothelin-regulated genes. In aim 2 we will focus on nocturnin. Preliminary results with microarrays have identified nocturnin as the most highly regulated gene in acute acidosis. Nocturnin is a circadian rhythm gene. Studies will examine the relationship between circadian rhythm and renal acidification and the role of nocturnin in acid signaling in the proximal tubule. In aim 3 we will study the endothelin B receptor. Previous studies have demonstrated that the endothelin B receptor can activate NHE3 and that it plays a key role in activation of NHE3 by acid. Two domains within the endothelin B receptor have been found to be key, the C-terminal tail and the second intracellular loop (ICL2). Studies will utilize the yeast two-hybid system to identify proteins that bind to ICL2. Using the yeast two-hybrid system, we have shown that Aldolase B binds to the C-terminal domain, and will now study its role in regulating NHE3. Lastly, studies will be performed to determine the specific role played by the endothelin B receptor in acid signaling. The last aim will study Pyk2. Pyk2 is activated in acidosis and we have shown that it is directly regulated by ambient pH, indicating that it can serve as a pH sensor. Studies will determine the specific domains/amino acids responsible for its pH sensitivity, and define the role that Pyk2 plays in the acid signaling cascade.

描述（由申请人提供）：慢性代谢性酸中毒诱导一系列稳态反应，旨在使血液pH值恢复至正常值。在肾近端小管中，这种反应包括氢离子分泌、氨合成和柠檬酸盐吸收的增加。该实验室的研究已经检查了这些适应发生的分子基础，重点是顶端膜Na/H反向转运蛋白NHE 3的调节。在最后一次资助期间，我们发现内皮素、Pyk 2、c-Src、ERK和黏着斑蛋白发挥了重要作用。拟议的研究继续关注近端小管感知细胞内pH值降低并传递信号以最终增加NHE 3活性的机制。研究分为四个目标。在目标1中，研究将利用微阵列来鉴定新的酸调节和内皮素调节基因。在目标2中，我们将重点关注转向。微阵列的初步结果已经确定了在急性酸中毒中最高度调节的基因。Nocturnin是一个昼夜节律基因。研究将检查昼夜节律和肾脏酸化之间的关系，以及在近端小管中酸性信号传导中的β-胡萝卜素的作用。目的3研究内皮素B受体。以前的研究已经证明内皮素B受体可以激活NHE 3，并且它在酸激活NHE 3中起关键作用。已发现内皮素B受体内的两个结构域是关键，C末端尾和第二胞内环（ICL 2）。研究将利用酵母双杂交系统来鉴定与ICL 2结合的蛋白质。使用酵母双杂交系统，我们已经表明，醛缩酶B结合的C-末端结构域，现在将研究其在调节NHE 3的作用。最后，将进行研究以确定内皮素B受体在酸信号传导中所起的特定作用。最后一个目标是研究Pyk 2。Pyk 2在酸中毒中被激活，我们已经证明它直接受环境pH值的调节，这表明它可以作为pH传感器。研究将确定负责其pH敏感性的特定结构域/氨基酸，并确定Pyk 2在酸信号级联中发挥的作用。