Mechanisms of NaCl Absorption in the Human Colon

人体结肠吸收 NaCl 的机制

• 批准号: 8442524
• 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/8442524
• 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; public health relevance; response; 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）： 与炎症性肠病（IBD）或食源性病原体感染相关的腹泻仍然是我们老患者群体中的一个主要健康问题。尽管医学取得了重大进展，腹泻病在全世界范围内仍然导致很高的发病率和死亡率。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且优越的干预策略至关重要。腹泻结果 由于肠道分泌增加和/或吸收减少。人体肠道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物腹泻有关，该基因编码 DRA（腺瘤中下调），这是一种已知在介导肠道氯化物吸收中发挥关键作用的蛋白质。最近，DRA 表达的显着降低已被证明是 IBD 患者腹泻的主要机制之一。然而，迄今为止，人们对腹泻疾病中 DRA 表达降低的分子机制知之甚少。为了阐明 IBD 中 DRA 表达下调的机制，我们的研究重点是肝核因子（HNF，许多转运蛋白表达所必需的转录因子）和 miRNA（已知在 IBD 患者和 IBD 患者中表达上调）的作用。 IBD 动物模型）。我们广泛的初步数据为 HNF 及其激活剂地塞米松 (DEX) 和共轭亚油酸 (CLA) 以及 miRNA 对 DRA 表达的调节提供了有力的证据。基于这些数据，我们假设发炎肠道中 HNF 的下调和某些 miRNA 的上调可能分别通过转录和转录后机制导致 DRA 表达减少。因此，当前的应用旨在利用体外（目标 1 和 2）和体内模型（目标 3）研究 HNF 和 miRNA 对 DRA 的调节，如下所示： 目标 1. 阐明 DRA 基础调节的详细机制HNF 启动子，降低 IBD 中 DRA 表达，并为 DEX 和 CLA 上调 DRA 建立分子基础；目标2：广泛分析miRNA对DRA转录后调控的机制；目标 3：分析 IBD 野生型和 IL-10 敲除小鼠模型中 HNF 和 miR 对 DRA 的调节。这些研究的结果应该明确 HNF 在基础、炎症或 CLA/DEX 介导的 DRA 上调中的作用，并且还将首次确定 miR 在正常和炎症条件下调节肠道 NaCl 吸收中的作用。这些研究还应该确定干预 IBD 相关腹泻的新目标。