CHLORIDE CHANNELS AND GASTRIC ACID SECRETION

胃溃疡疾病的治疗控制取决于控制HCl分泌的干预措施。 该提案的广泛，长期目标是确定参与调节HCl分泌的分子和机制。 HCl的分泌涉及胃H/K ATP酶和K的转运系统，以提供H/K ATP酶和C1，以提供HCl生产的C1当量。 在这个建议中要测试的工作假设是，刺激的兔胃壁细胞的顶膜包含C1和K通道，这是密切相关的和必不可少的调节胃酸分泌。 C1通道（C1 C-2G）是本实验室克隆的一种整流性钾通道，受Ca ~（2+）或Mg ~（2+）、CaMK Ⅱ、PKA、电压和细胞外pH值的调节，K通道是一种内向整流性钾通道，受PKA和细胞外pH值的调节，二价阳离子也可能起作用。 已获得候选K通道克隆RBHIK 1，并将其特性与天然通道的特性进行比较和对比。 K和C1的生理相关向外运动基本上由相同的效应器调节，并且对电和化学环境的变化做出类似的反应。 计划中的研究是针对了解细胞内离子之间的相互作用，促进整流，蛋白激酶，电压和pH值的影响，在促进外向运动的C1 CIC-2G和K的本地和克隆内向整流K通道。 功能研究将通过使用含有阳离子结合位点、磷酸化位点和pH传感器位点突变的通道cDNA的相关结构研究来补充。 适用于CI和K通道的具体目的是研究：1）阳离子在通道整流中的作用; 2）蛋白激酶在C1和K通道功能中的作用; 3）质子在C1和K通道功能中的作用;以及4）非分泌（静息）和分泌（刺激）状态下胃壁细胞中通道的位置。前3个目标将使用功能以及相关的结构方法进行研究。目标4将使用基于通道序列知识的结构探针来实现。 这些研究致力于解决有关调节HCl分泌的分子和机制的基本问题。

Therapeutic control of gastric ulcer disease depends upon interventions which control HCl secretion. The broad, long term objectives of this proposal are to define the molecules and mechanisms involved in regulated HCl secretion. HCl secretion involves the gastric H/K ATPase and a transport system for K to supply the H/K ATPase and for C1 to provide equivalents of C1 for HCl production. The working hypothesis to be tested in this proposal is that the apical membrane of the stimulated rabbit gastric parietal cell contains both C1 and K channels which are intimately associated with and essential for regulated gastric HCl secretion. The C1 channel, C1C-2G was cloned in this laboratory, and it is a rectifier which is controlled by Ca2+ or Mg2+, CaMKII as well as PKA, voltage, and extracellular pH. The K channel appears to be an inwardly rectifying K channel which is regulated by PKA and extracellular pH. Divalent cations may also play a role. A candidate K channel clone, RBHIK1, has been obtained and its properties will be compared and contrasted with those of the native channel. The physiologically relevant outward movement of both K and C1 are regulated by essentially the same effectors and respond similarly to changes in the electrical and chemical environments. The planned studies are directed toward understanding the interactions between intracellular ions in promoting rectification, the effects of protein kinases, voltage, and pH in promotion of outward movements of C1 by CIC-2G and of K by the native and cloned inwardly rectifying K channel. Functional studies will be complemented by correlated structural studies using channel cDNAs containing mutations of the cation binding sites, phosphorylation sites, and pH sensor sites. The Specific Aims which apply to both the CI and K channels are to study: 1) the role of cations in rectification of the channels; 2) the role of protein kinases in C1 and K channel function; 3) the role of protons in C1 and K channel function; and 4) the location of the channels in the gastric parietal cell in the non-secreting (resting) and secreting (stimulated) states. The first 3 aims will be studied using functional as well as correlated structural approaches. Aim 4 will be accomplished using structural probes based on knowledge of the sequence of the channels. These studies strive to address the fundamental questions regarding the molecules and mechanisms involved in regulated HCl secretion.