Surgical Studies of Gut Permeability

 描述(申请人提供)：急性肠道屏障功能障碍通常发生在有严重外科疾病的患者中，如创伤、烧伤、败血症、出血和大规模外科手术，导致管腔有毒物质和细菌转移到血流中。由于急性屏障功能障碍的确切机制尚不清楚，保护屏障完整性和促进其功能恢复的有效治疗方法有限，导致外科危重患者肠漏死亡。近年来，长非编码RNAs(Long Non Coding RNAs，LncRNAs)已成为一类新的基因表达调控因子，参与多种生物学过程和多种人类疾病。这一竞争性更新应用的目的是通过开展一系列多学科研究，确定LncRNAs H19和SPRY4-IT1在关键手术条件下控制紧密连接(TJ)表达和肠道通透性方面的功能。我们的初步结果表明：a)在手术条件下，小鼠的靶向缺失H19保护TJ屏障功能，而H19的过表达抑制TJ蛋白的表达并增加细胞旁通透性；b)lncRNA SPRY4-IT1沉默使TJ mRNAs不稳定，从而增加上皮细胞旁细胞通透性；SPRY4-IT1与TJ mRNAs结合需要RNA结合蛋白Hur；c)减少细胞多胺使lncRNA H19水平增加，但降低lncRNA SPRY4-IT1。基于这些令人兴奋的观察，我们推测lncRNAs H19和SPRY4-IT1在关键手术条件下通过与Hur相互作用在TJ表达和肠道屏障功能的调节中发挥重要作用，并且它们的细胞丰度受多胺调节。提出了三个特定的目的来验证这一假说：1)确定在关键手术应激过程中，lncRNAs H19和SPRY4-IT1在调节TJ表达和屏障功能中的确切作用；2)表征Hur与lncRNAs H19和SPRY4-IT1在手术应激反应中调节TJ蛋白表达的相互作用；以及3)确定多胺是否作为新的lncRNAs H19和SPRY4-IT1表达的调节因子。这些特定目标的完成将在概念上取得重大进展，将lncRNA介导的TJ表达与危重外科疾病患者的肠道通透性联系起来，并将为开发新的、更有效的治疗方法以维护上皮屏障的完整性奠定基础。

 DESCRIPTION (provided by applicant): Acute gut barrier dysfunction occurs commonly in patients with critical surgical disorders such as trauma, burns, sepsis, hemorrhage, and massive surgical operations, leading to the translocation of luminal toxic substances and bacteria to the blood stream. Since the exact mechanism underlying the acute barrier dysfunction remains largely unknown, effective therapies to protect the barrier integrity and enhance its functional recovery are limited, contributing to death in critically surgical patients with leaky gut. Recentl, long noncoding RNAs (lncRNAs) have emerged as a novel class of master regulators of gene expression and are fundamentally involved in many biological processes and different human diseases. The goal of this competitive renewal application is to determine the functions of lncRNAs H19 and SPRY4-IT1 in the control of tight junction (TJ) expression and gut permeability under critical surgical conditions by carrying out a series of multi-disciplinary studies. Our preliminary results indicate that a) target deletion of H19 in mice protects the TJ barrier function under surgical conditions, whereas H19 overexpression represses TJ protein expression and increases paracellular permeability; b) lncRNA SPRY4-IT1 silencing destabilizes TJ mRNAs and thus increases epithelial paracellular permeability; SPRY4-IT1 binding to TJ mRNAs requires the RNA-binding protein HuR; and c) decreasing cellular polyamines increases lncRNA H19 levels but decreases lncRNA SPRY4-IT1. Based on these exciting observations, we HYPOTHESIZE that lncRNAs H19 and SPRY4-IT1 play an important role in the regulation of TJ expression and gut barrier function by interacting with HuR in critica surgical conditions and their cellular abundances are regulated by polyamines. Three specific aims are proposed to test the hypothesis: 1) to define the exact roles of lncRNAs H19 and SPRY4-IT1 in the regulation of TJ expression and barrier function during critical surgical stress; 2) to characterize the interactions between HuR and lncRNAs H19 and SPRY4-IT1 in the regulation of TJ protein expression in response to surgical stress; and 3) to determine if polyamines function as novel regulators of expression of lncRNAs H19 and SPRY4-IT1. Completion of these specific aims will make a significant conceptual advance by linking the lncRNA-mediated TJ expression with gut permeability in patients with critical surgical illness and will create a fundamental base for development of novel and more effective therapies to preserve the epithelial barrier integrity.