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The function of ezrin in stimulus-coupled acid secretion

埃兹蛋白在刺激耦合酸分泌中的功能

基本信息

批准号：
7491958
负责人：
XUEBIAO YAO
金额：
$ 1.79万
依托单位：
MOREHOUSE SCHOOL OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
1999
资助国家：
美国
起止时间：
1999-09-01 至 2008-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7491958
关键词：
Acids Actin-Binding Protein Actins Address Am 80 Apical Binding Biological Assay Cell Polarity Cell membrane Cell physiology Cells Chemicals Complex Coupled Couples Coupling Cyclic AMP-Dependent Protein Kinases Cytoskeleton Data Disease Docking Electrons Epithelial Epithelial Cells Epitopes Fluorescence Fluorescence Microscopy Gastric Acid Gastric Glands Gastric Parietal Cells Gastroesophageal reflux disease Gland Goals Green Fluorescent Proteins H(+)-K(+)-Exchanging ATPase Hormones In Vitro Mediating Membrane Microscopic Molecular Monitor Optical reporter Peptic Ulcer Peptides Phosphoproteins Phosphorylation Phosphorylation Site Process Protein Kinase Proteins Regulation Reporter Research Role Signal Transduction Signaling Protein Stimulus Stomach Time Vesicle apical membrane chemical genetics crosslink design ezrin syntaxin 3

项目摘要

The digestive function of the stomach depends on acidification of the gastric lumen. Acid secretion into the lumen is triggered by activation of a cAMP-dependent protein kinase (PKA) cascade, which ultimately results in the insertion of gastric H,K-ATPases into the apical plasma membranes of parietal cells. This relocation of the H,K-ATPase occurs concomitantly with extensive remodeling of the actin cytoskeleton at the apical membrane, which is also an essential step in the activation of acid secretion. While these aspects of parietal cell activation are well defined, the molecular mechanisms that couple the PKA signaling cascade to mobilization of H,K-ATPases and cytoskeletal remodeling are not known. A coupling protein is ezrin, an 80 kDa phosphoprotein, whose phosphorylation by PKA is required for parietal cell activation. However, little is known regarding the molecular mechanism(s) by which ezrin operates in gastric acid secretion. The long-term goal of our research is to delineate how ezrin orchestrates stimulus-coupled gastric acid secretion. To address this question, three Specific Aims are proposed: first, we will evaluate how phospho-ezrin interacts with IQGAP2 using epitope-tagging, chemical footprinting, and crosslinking approaches. These studies will involve a detailed analysis of the structural determinants that mediate a direct ezrin-IQGAP2 contact. Binding domain data will be used to design peptides that potently and specifically perturb ezrin-IQGAP2 interactions in in vitro binding assays. The function of this interaction will then be determined by the effects of the peptides on acid secretion using permeabilized gastric glands. Second, we will determine how ezrin interacts with syntaxin 3 to facilitate the insertion of H,K-ATPase into the apical membrane upon the stimulation. These studies will be facilitated by real time microscopic analyses of parietal cell activation using fluorescence reporters. Third, we plan to define the role of ezrin-PALSl interaction in the apical membrane remodeling related to the cell activation by first pin-pointing their binding domains. The importance of such an interaction in acid secretion will then be evaluated by functional assay coupled with ultrastructural analysis. Studying the molecular and cellular mechanisms underlying parietal cell activation is of substantial significance in understanding the cellular physiology of regulated epithelial secretion in the gut, and is also expected to be of great benefit in leading to pharmacological strategies for correcting abnormal gastric acid secretion in disorders such as peptic ulcers, and gastroesophageal reflux disease.

胃的消化功能取决于胃腔的酸化。酸分泌