Surgical Studies on Mucosal Homeostasis

有严重外科疾病的患者，如创伤、热损伤、休克、败血症和 大手术通常合并急性肠黏膜损伤和 在流血。肠道上皮完整性的破坏会导致败血症，在某些情况下会起到 引发多器官功能障碍综合征(MODS)的触发因素是 危重病人。加强黏膜防御和促进上皮细胞生长的有效治疗方法 外科危重疾病患者急性损伤后的修复有限，有助于 大量粘膜出血，修复受损，肠道屏障功能障碍。在上一次 资助期内，我们已经证明了蛋白磷酸酶2A(PP2A)相关蛋白 α-4在肠粘膜再生和防御中发挥重要作用，但其确切的 α4调节肠道内环境平衡的机制在很大程度上仍不清楚。 非编码RNAs(NcRNAs)，包括microRNAs(MiRNAs)和Long ncRNAs(LncRNAs)，具有 新近出现的一类新的肠上皮细胞动态平衡的主要调节者 而且还与不同的人类疾病有关。MiRNAs和lncRNAs调节 目的基因的表达，从而调节各种细胞过程。 我们的初步结果表明，a)在小鼠中靶向删除α4降低了 肠粘膜miR-503和LncRNA uc.230；b)miR-503和 UC.230经其拮抗基因转染后被抑制的肠上皮修复 C)miR-503抑制血管内皮细胞的表达 抗酶(AZ；多胺生物合成的负调控因子)，而uc.230上调 Rac1和凋亡抑制蛋白1(IAP1)。基于这些令人兴奋的观察，我们 假设α4通过调节miRNA miR-4促进肠上皮细胞动态平衡 503和LncRNAuc.230在危重手术条件下。 提出了三个具体的目标来检验这一假设：1)检查基因的表达谱 α-4缺陷肠上皮对手术应激反应的miRNA和lncRNA 为了确定miR-503和uc.230在α4调节的粘膜修复和修复中的确切作用 3)确定miR-503和uc.230调控表达的机制 AZ、rac1和IAP1的。完成这些具体目标将在以下方面取得概念上的进步 关键手术条件下α-4/ncRNA通路与肠上皮细胞动态平衡的关系 这些研究还将为开发新的治疗方法奠定基础 在我们的VA患者中保持上皮完整性，从而降低 靶向α4的大量粘膜损伤和炎症、延迟修复、脓毒症和MODS 及其调控的ncRNA。

Patients with critical surgical disorders such as trauma, thermal injury, shock, sepsis, and massive surgical operations are commonly complicated with acute gut mucosal injury and bleeding. Disruption of the gut epithelial integrity causes sepsis and in some instances acts as the trigger that drives multiple organ dysfunction syndrome (MODS), a leading cause of death in critically ill patients. Effective therapies to enhance mucosal defense and promote epithelial repair after acute injury in patients with critical surgical illnesses are limited, contributing to massive mucosal hemorrhage, impaired repair, and gut barrier dysfunction. During the previous funding periods, we have demonstrated that protein phosphatase 2A (PP2A)-associated protein α4 plays an important role in intestinal mucosal regeneration and defense, but its exact mechanism underlying α4-regulated intestinal homeostasis remains largely unknown. Noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long ncRNAs (lncRNAs), have recently emerged as a novel class of master regulators of the intestinal epithelium homeostasis and are also implicated in different human diseases. miRNAs and lncRNAs modulate expression of target genes and thus regulate a variety of cellular processes. Our preliminary results indicate that a) targeted deletion of α4 in mice decreased the levels of mucosal miR-503 and lncRNA uc.230 in the intestine; b) specific inhibition of miR-503 and uc.230 by transfection with their antagonisms repressed intestinal epithelial repair after wounding and also enhanced epithelial cell apoptosis; and c) miR-503 inhibited expression of antizyme (AZ; a negative regulator of polyamine biosynthesis), whereas uc.230 up-regulated Rac1 and inhibitor of apoptosis protein 1 (IAP1). Based on these exciting observations, we HYPOTHESIZE that α4 promotes intestinal epithelial homeostasis by modulating miRNA miR- 503 and lncRNA uc.230 in critical surgical conditions. Three specific aims are proposed to test the hypothesis: 1) to examine the expression profiles of miRNAs and lncRNAs in the α4-deficient intestinal epithelium in response to surgical stress; 2) to determine the exact roles of miR-503 and uc.230 in α4-regulated mucosal repair and apoptosis; and 3) to define the mechanisms by which miR-503 and uc.230 regulate expression of AZ, Rac1, and IAP1. Completion of these specific aims will make a conceptual advance by linking α4/ncRNA pathway with gut epithelium homeostasis under critical surgical conditions. These studies will also create a fundamental basis for development of novel therapies to preserve epithelial integrity in our VA patients, thus decreasing morbidity and mortality of massive mucosal injury and inflammation, delayed repair, sepsis, and MODS by targeting α4 and its regulatory ncRNAs.