Role of Epithelia In Ischemia Reperfusion Injury

描述（申请人提供）：肠、肺等粘膜器官是高度维管化的器官，代谢需求广泛。上皮细胞排列在肠内，其功能是协调多种粘膜反应，并且由于其解剖位置，是血流量减少和由此引起的缺氧介导的损伤的主要目标。我们之前的研究探讨了肠上皮细胞对缺氧的反应，这些研究确定了一个由缺氧诱导因子（hypoxia inducible factor， HIF）介导的转录信号通路。HIF的激活导致协同诱导一簇顶端定位的屏障保护基因产物。在本提案中，我们将验证HIF协调保护性上皮对缺氧反应的假设。本文提出了3个具体目标来验证这一假设。首先，我们将利用新开发的表达肠道特异性HIF功能丧失和获得的小鼠模型来回答关于健康和肠道疾病期间HIF激活的基本问题。其次，我们将以最近的研究结果为基础，探索体外和体内腺嘌呤核苷酸代谢和信号传导的影响。特别是，我们将研究顶端定位的膜腺嘌呤核苷酸外切酶和腺苷受体如何在缺氧时调节白细胞介导的屏障破坏。第三，我们将定义白细胞在肠上皮细胞间运输的分子事件，因为它们与缺氧有关。特别是，我们将阐明缺氧调节的表面分子的分子细节，这些表面分子协调白细胞穿越顶膜表面。本提案的总体目的是阐明介导粘膜上皮对缺氧和炎症反应的转录信号事件。

DESCRIPTION (provided by applicant): Mucosal organs such as the intestine and lung are highly vascular organs with extensive metabolic demands. Epithelial cells which line the intestine function to orchestrate a multitude of mucosal responses, and given their anatomic location, are primary targets for diminished blood flow and resultant hypoxia-mediated damage. Our previous studies have explored the response of intestinal epithelial cells to hypoxia and these studies defined a transcriptional signaling pathway mediated by hypoxia-inducible factor (HIF). Activation of HIF results in the coordinated induction of a cluster of apically-localized, barrier protective gene products. In this proposal, we will test the hypothesis that HIF coordinates protective epithelial responses to hypoxia. 3 specific aims are proposed to test this hypothesis. First, we will utilize newly developed murine models which express intestinal specific loss and gain of HIF function to answer basic questions regarding HIF activation in health and during intestinal disease in vivo. Second, we will build on recent findings to explore the influence of adenine nucleotide metabolism and signaling in vitro and in vivo. In particular, we will study how apically-localized membrane adenine nucleotide ecto-enzymes and adenosine receptors contribute to the regulation of leukocyte-mediated barrier disruption during hypoxia. Third, we will define molecular events of leukocyte trafficking across intestinal epithelial cells as they relate to hypoxia. In particular, we will elucidate the molecular details of hypoxia-regulated surface molecules which orchestrate leukocyte transit across the apical membrane surface. The overall aim of this proposal is to elucidate the transcriptional signaling events mediating mucosal epithelial responses to hypoxia and inflammation.