FUNCTION & REGULATION OF GASTRIC NA/K/2CL COTRANSPORTERS

功能

• 批准号: 6517527
• 负责人: CHRISTIAN Y LYTLE
• 金额: $ 15.1万
• 依托单位: UNIVERSITY OF CALIFORNIA RIVERSIDE
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-01 至 2004-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6517527
• 关键词: cell migration; chloride ion; gastric juice; gastric mucosa; gastrointestinal absorption /transport; hydrochloric acid; hydrogen potassium exchanging ATPase; laboratory rabbit; laboratory rat; membrane transport proteins; microspectrophotometry; potassium ion; protein localization; protein structure function; secretion; sodium ion

The gastric mucosa secretes digestive hydrochloric acid and pepsin in coordination with dietary intake. Although it is now axiomatic that parietal cells secrete HCl, a growing body of evidence indicates that these cells undergo major morphological, biochemical, and functional changes as they migrate down into the neck and base of the gastric gland. The nature and functional significance of these changes are poorly understood. We show that parietal cell transformation includes a sudden and prodigious expression of the secretory Na-K-2Cl cotransporter (NKCC). The migration-associated expression of NKCC is topologically correlated with loses of Cl/HCO3 exchanger (AE2) and H,K-ATPase activity, and with expression of aquaporin-4 water channels. We hypothesize that downwardly-migrating parietal cells might undergo a programmed conversion of their principal function from acidic chloride (HCl) secretion to nonacidic chloride (NaCl) secretion. The secretion of a saline fluid volume by parietal cells in the base of the gland might serve to flush the lumen of local pepsinogen and distal acid. The project proposed here consists of four complementary studies. Aim 1 will determine the functional consequences of NKCC expression and AE2 loss during parietal cell migration on intracellular Cl- homeostasis and vectorial Cl- transport by microspectrofluorometric imaging of isolated gastric glands. Aim 2 will begin to delineate the signals, receptors, and intracellular mediators that regulate NKCC in basilar parietal cells in vitro and in vivo. Aim 3 will directly test whether parietal cells in the gland base cease to function as robust acid secretors, as previous evidence has suggested. Finally, Aim 4 will map the cellular and subcellular distribution of K-Cl cotransporter-1 (KCC1) in gastric mucosa and begin to assess the possibility that K-Cl cotransporter-1 (KCC1) may contribute to apical K+ recycling in parietal cells. Completion of these aims will begin to clarify the functional consequences of the migration-associated differentiation of parietal cells.

胃粘膜分泌消化盐酸和胃蛋白酶与饮食摄入协调。 虽然现在壁细胞分泌HCl是不言自明的，但越来越多的证据表明，这些细胞在向下迁移到胃腺的颈部和基部时经历了主要的形态、生化和功能变化。 这些变化的性质和功能意义知之甚少。 我们发现，壁细胞转化包括突然和巨大的表达分泌型钠-钾-2Cl协同转运蛋白（NKCC）。 NKCC的迁移相关表达与Cl/HCO 3交换器（AE 2）和H，K-ATP酶活性的丧失以及水通道蛋白-4水通道的表达具有拓扑学相关性。 我们推测，向下迁移的壁细胞可能会经历一个程序化的转换，其主要功能从酸性氯化物（HCl）分泌到非酸性氯化物（NaCl）分泌。 腺基部壁细胞分泌的盐水可能用于冲洗胃蛋白酶原和远端酸的内腔。 本报告提出的项目包括四项相辅相成的研究。 目的1将通过离体胃腺的显微荧光光谱成像来确定壁细胞迁移期间NKCC表达和AE 2损失对细胞内氯离子稳态和矢量氯离子转运的功能后果。 目的2将开始描述在体外和体内调节基底壁细胞NKCC的信号、受体和细胞内介质。 目标3将直接测试腺基部的壁细胞是否像以前的证据所表明的那样停止作为强有力的酸分泌物的功能。 最后，目的4将绘制K-Cl协同转运蛋白-1（KCC 1）在胃粘膜中的细胞和亚细胞分布，并开始评估K-Cl协同转运蛋白-1（KCC 1）可能有助于壁细胞顶端K+再循环的可能性。 这些目标的完成将开始澄清壁细胞迁移相关分化的功能后果。