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

功能

• 批准号: 6363036
• 负责人: CHRISTIAN Y LYTLE
• 金额: $ 14.66万
• 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 2003-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6363036
• 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.

胃粘膜与饮食摄入相配合，分泌消化用盐酸和胃蛋白酶。 尽管现在壁细胞分泌 HCl 已是不言自明的事实，但越来越多的证据表明，这些细胞在向下迁移到胃腺颈部和基部时，会经历重大的形态、生化和功能变化。 人们对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分泌型 Na-K-2Cl 协同转运蛋白 (NKCC) 的突然和大量表达。 NKCC 的迁移相关表达与 Cl/HCO3 交换器 (AE2) 和 H,K-ATP 酶活性的丧失以及 aquaporin-4 水通道的表达在拓扑上相关。 我们假设向下迁移的壁细胞可能会经历其主要功能从酸性氯化物（HCl）分泌到非酸性氯化物（NaCl）分泌的程序性转换。 腺体底部壁细胞分泌的大量盐水可能有助于冲洗局部胃蛋白酶原和远端酸的管腔。 这里提出的项目由四项补充研究组成。 目标 1 将通过离体胃腺的显微分光荧光成像确定壁细胞迁移过程中 NKCC 表达和 AE2 丢失对细胞内 Cl- 稳态和矢量 Cl- 转运的功能影响。 目标 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 将直接测试腺体基底的壁细胞是否不再像之前的证据所暗示的那样，停止作为强大的酸分泌者发挥作用。 最后，目标 4 将绘制 K-Cl 协同转运蛋白-1 (KCC1) 在胃粘膜中的细胞和亚细胞分布图，并开始评估 K-Cl 协同转运蛋白-1 (KCC1) 可能有助于壁细胞顶端 K+ 循环的可能性。 这些目标的完成将开始阐明壁细胞迁移相关分化的功能后果。