Mechanisms of NaCl Absorption in the Human Colon

人体结肠吸收 NaCl 的机制

• 批准号: 8774198
• 负责人: Pradeep K Dudeja
• 金额: --
• 依托单位: JESSE BROWN VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8774198
• 关键词: Affect; Animal Model; Anti-Inflammatory Agents; Bacterial Infections; Bicarbonates; Binding; Binding Sites; Carrier Proteins; Cell Culture Techniques; Cells; Chloride Anion Exchanger; Chloride Ion; Chlorides; Colitis; Colon; Conjugated Linoleic Acids; Coupled; Data; Dexamethasone; Diarrhea; Disease; Disease model; Down-Regulation; Electrolytes; Exhibits; Functional disorder; Genes; Genetic Transcription; Health; Healthcare; Hepatic; Human; In Vitro; Indium; Infection; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Inflammatory disease of the intestine; Interleukin-10; Intervention; Intestinal Secretions; Intestines; Knockout Mice; Knowledge; Mediating; Medical; Messenger RNA; MicroRNAs; Modeling; Molecular; Molecular Biology; Morbidity - disease rate; Mus; Mutation; Nuclear; Outcome Study; Patients; Pharmaceutical Preparations; Play; Post-Transcriptional Regulation; Proteins; Regulation; Reporting; Repressor Proteins; Role; Route; SLC26A3 gene; Signal Transduction; Site; Therapeutic; Time; Transcriptional Regulation; Transfection; Untranslated Regions; Up-Regulation; Veterans; Water Movements; absorption; base; design; foodborne; foodborne pathogen; in vivo; in vivo Model; mortality; mouse model; new therapeutic target; novel; operation; overexpression; patient population; promoter; protein expression; response; targeted treatment; transcription factor

DESCRIPTION (provided by applicant): Diarrhea associated with inflammatory bowel diseases (IBD) or infections by food-borne pathogens remains a major health problem in our veteran patient population. Despite major medical advances, diarrheal diseases still result in very high morbidity and mortality worldwide. Therefore, a better understanding of the pathophysiology of diarrhea associated with these diseases is critical for designing novel and superior strategies for intervention. Diarrhea results from increased intestinal secretion and/or decreased absorption. A major route of electrolyte absorption in the human intestine involves coupled operation of Na+/H+ and Cl-/HCO3- exchangers. The gene Slc26a3, whose mutations are associated with congenital chloride diarrhea, encodes DRA (Down-Regulated in Adenoma), a protein known to play a critical role in mediating intestinal chloride absorption. Recently, significant reduction of DRA expression has been shown to be one of the major mechanisms responsible for diarrhea in IBD patients. To date, however, very little is known about the molecular mechanisms involved in decreasing DRA expression in diarrheal diseases. In order to elucidate the mechanisms underlying the downregulation of DRA expression in IBD, our studies focused on the role of hepatic nuclear factors (HNFs, transcription factors essential for the expression of many transport proteins) and miRNAs (known to be upregulated in IBD patients and animal models of IBD). Our extensive preliminary data provided strong evidence for the regulation of DRA expression by both HNFs and their activators dexamenthasone (DEX) and conjugated linoleic acids (CLAs), as well as miRNAs. Based on these data, we hypothesize that a down-regulation of HNFs and upregulation of certain miRNAs in inflamed gut may underlie the decrease in DRA expression via transcriptional and post-transcriptional mechanisms, respectively. The current application is, therefore, designed to investigate the regulation of DRA by HNFs and miRNAs utilizing both in vitro (Aims 1 & 2) and in vivo models (Aim 3) as follows: Aim 1. Elucidate detailed mechanisms underlying basal regulation of DRA promoter by HNFs, in decreased DRA expression in IBD and to establish the molecular basis for the upregulation of DRA by DEX and CLAs; Aim 2: Extensively analyze the mechanisms underlying post-transcriptional regulation of DRA by miRNAs; and Aim 3: Analyze the regulation of DRA by HNFs and miRs in wild type and IL-10 knock out mouse model for IBD. The outcome of these studies should define the role of HNFs in basal, inflammatory or CLA/DEX-mediated upregulation of DRA, and will also establish for the first time, the role of miRs in the modulation of intestinal NaCl absorption under normal and inflammatory conditions. These studies should also identify novel targets for intervention in IBD associated diarrhea.

描述（由申请人提供）： 与炎症性肠道疾病（IBD）或食源性病原体感染有关的腹泻仍然是我们资深患者人群的主要健康问题。尽管医疗的进展重大，但腹泻疾病仍导致全球发病率和死亡率很高。因此，更好地了解与这些疾病相关的腹泻的病理生理学对于设计新颖和出色的干预策略至关重要。腹泻结果 肠道分泌和/或吸收减少。人类肠中电解质吸收的主要途径涉及Na+/H+和Cl-/Hco3-交换器的耦合操作。基因SLC26A3的突变与先天性氯化腹泻有关，编码DRA（在腺瘤中下调），该蛋白质已知在介导肠氯化物吸收中起着至关重要的作用。最近，DRA表达的显着降低已被证明是导致IBD患者腹泻的主要机制之一。然而，迄今为止，关于降低腹泻疾病中DRA表达的分子机制知之甚少。为了阐明IBD中DRA表达下调的机制，我们的研究集中于肝核因子的作用（HNFS，转录因子，对于许多转运蛋白表达）和miRNA（已知在IBD患者中已上调） IBD的动物模型）。我们广泛的初步数据为HNF及其激活剂右has（DEX）和共轭亚油酸（CLAS）以及miRNA对DRA表达的调节提供了有力的证据。基于这些数据，我们假设HNF的下调和在发炎的肠道中某些miRNA的上调可能是通过转录和转录后机制分别降低DRA表达的降低。因此，当前的应用旨在调查HNFS和miRNA对DRA的调节，并利用体外（AIMS 1和2）和体内模型（AIM 3）（AIM 3），如下：AIM 1。阐明了DRA基础调节的详细机制HNFS的启动子在IBD中的DRA表达降低，并建立了通​​过DEX和CLAS上调DRA的分子基础； AIM 2：广泛分析miRNA对DRA转录后调节的机制；和目标3：分析HNF和MIR在野生型中对DRA的调节，而IL-10敲除IBD的小鼠模型。这些研究的结果应定义HNF在DRA的基底，炎症或CLA/DEX介导的上调中的作用，并且还将首次确定miR在正常和炎症条件下肠NACL吸收调节中的作用。这些研究还应确定干预IBD相关腹泻的新目标。