REGULATION OF INTESTINAL EPITHELIAL RESTITUTION

描述（由申请人提供）： 项目摘要/摘要早期肠粘膜恢复的调节缺陷是各种关键病理状态的基础，如急性粘膜损伤/出血、糜烂/溃疡修复受损、上皮完整性破坏和上皮屏障功能障碍。由于浅表创伤后早期快速粘膜修复的确切机制尚不清楚，临床上保护肠上皮完整性的有效治疗方法有限，特别是在创伤和脓毒症等外科危重疾病患者中。损伤和/或溃疡后正常肠粘膜完整性的恢复需要上皮细胞的决定，其调节控制各种基因表达的信号网络。转录后事件，特别是改变mRNA的周转和翻译，是哺乳动物细胞控制基因表达的主要机制，以应对各种压力。mRNA稳定性和翻译的变化主要由RNA结合蛋白（RBP）和microRNA（miRNA）控制，它们是维持肠道上皮完整性的主要调节因子。然而，关于RBP和miRNA在急性损伤后粘膜快速恢复机制中的作用知之甚少。HuR是最突出的翻译和周转调节RBP之一，最近显示调节细胞运动。我们的初步结果表明：a）HuR沉默抑制体外模型中肠上皮细胞（IEC）在受伤区域的迁移; B）组织特异性HuR敲除抑制损伤后早期肠粘膜修复; c）miR-195过表达抑制体外早期上皮修复，但这种抑制可通过增加HuR水平来挽救。基于这些令人兴奋的观察结果，我们假设HuR通过改变编码细胞迁移调节因子的靶mRNA的稳定性和翻译，对损伤后的肠上皮恢复至关重要。 蛋白质，其作用由给定的miRNA调节。提出了三个具体目标来检验这一假设。1)为了确定HuR在术后早期肠粘膜恢复中的确切作用， 急性损伤。2)目的：明确创伤后肠上皮细胞中HuR的新靶基因及其在mRNA稳定性和翻译调控中的作用。3)研究HuR和给定miRNAs之间的相互作用，以控制靶mRNA的稳定性和翻译，从而响应上皮损伤。这些特定目标的完成将通过将HuR/miRNA介导的转录后基因调控与肠中的早期粘膜恢复联系起来而在概念上取得重大进展，并将为开发肠粘膜损伤相关疾病的新治疗方法和在各种临床条件下维持上皮完整性奠定基础。

DESCRIPTION (provided by applicant): Project Summary/Abstract Defective regulation of early intestinal mucosal restitution underlies various critical pathological states such as acute mucosal injury/hemorrhage, impaired repair of erosions/ulcers, disruption of epithelial integrity, and epithelial barrier dysfunction. Since the exact mechanisms of early rapid mucosal restitution after superficial wounds are still obscure, effective therapies to preserve gut epithelial integrity in clinic are limited, especially in patiets with critical surgical illnesses such as trauma and sepsis. The restoration of normal intestinal mucosal integrity after injury and/or ulceration requires epithelial cell decisions that regulate signaling networks controlling expression of various genes. Posttranscriptional events, particularly altered mRNA turnover and translation, are major mechanisms by which mammalian cells control gene expression in response to various stresses. Changes in mRNA stability and translation are predominantly governed by RNA-binding proteins (RBPs) and microRNAs (miRNAs) that are emerged as master regulators of maintenance of gut epithelial integrity. However, little is known about the roles of RBPs and miRNAs in the mechanisms underlying rapid mucosal restitution after acute injury. HuR is among the most prominent translation and turnover regulatory RBPs and is recently show to regulate cell motility. Our preliminary results indicate that a) HuR silencing represses intestinal epithelial cell (IEC) migration over the wounded area in an in vitro model; b) tissue specific HuR knockout inhibits early intestinal mucosal repair after injury; and c) miR-195 overexpression represses early epithelial repair in vitro, but this repression is rescued by increasing HuR levels. Based on these exciting observations, we HYPOTHESIZE that HuR is essential for intestinal epithelial restitution after injury by altering the stability and translation of target mRNAs encoding cell migration-regulatory proteins and its effect is regulated by given miRNAs. Three specific aims are proposed to test the hypothesis. 1) To determine the exact role of HuR in early intestinal mucosal restitution after acute injury. 2) To define new target mRNAs of HuR and its role in the regulation of mRNA stability and translation in the intestinal epithelium after wounding. 3) To investigate the interactions between HuR and given miRNAs in the control of stability and translation of target mRNAs in response to epithelial injury. Completion of these specific aims will make a significant conceptual advance by linking HuR/miRNA-mediated posttranscriptional gene regulation with early mucosal restitution in the intestine and will create a fundamental base for development of new therapeutic approaches for gut mucosal injury-related diseases and for maintaining epithelial integrity under various clinical conditions.