Apical Polarity Complex Signaling in Inflammation in Intestinal Epithelia

描述(申请人提供)：我们实验室最近发表的工作表明，在肿瘤坏死因子刺激下，在DSS小鼠结肠炎模型和炎症性肠病患者中，肠上皮细胞中非典型PKC的表达显著下调。在这个项目中，我们将从力学上分析aPKC缺失对细胞功能、信号通路和分子效应器的影响，这些都是已知在这些细胞中IBD的病理生理中必不可少的。我们的初步数据有力地表明，在动物模型和患者中观察到的aPKC活性的降低足以触发经典的I？B通路的激活，而不依赖于TNFR。这一观察结果开启了这样一种可能性，即即使去除了最初的细胞因子刺激，蛋白激酶C下游的信号也可能会建立一种负反馈，使上皮细胞处于“发炎”状态。如果我们的假设是正确的，打破这一循环可能有助于迅速纠正屏障缺陷和上皮细胞分泌细胞因子，这将是慢性肠道炎症所希望的。此外，由于这些通路是上皮细胞特有的，了解它们可能会使组织特异性干预成为可能。目标1将研究这一现象的机制方面和后果。我们的初步数据还显示，在上皮损伤中也发生了类似的短暂事件，这表明它可能也参与了上皮恢复的早期阶段，这将在目标2中进行测试。最后，在目标1和2中研究的分子机制将在目标3的结肠炎动物模型的背景下进行分析。总之，该项目有望建立一种全新的信号通路，确定其正常功能，并带来新的，因为你们可能是未知的治疗靶点来调节上皮对炎症的反应。 与公共卫生相关：炎症性肠病是一种免疫系统的多因素异常反应，除其他影响外，还影响肠腔内的细胞层，即上皮细胞。这个项目研究了一种新的细胞内信号通路，它可以抵消炎症的影响。重要的是，如果我们的假设是正确的，抑制这一新途径可能有助于炎症效应的持久存在，并可能提供新的意想不到的治疗机会。

DESCRIPTION (provided by applicant): Recent published work in our laboratory has shown a profound downregulation of atypical PKC in intestinal epithelial cells under TNF¿ stimulation, in the DSS model of murine colitis, and in Inflammatory Bowel Disease patients. In this project we will analyze mechanistically the consequences of aPKC loss on cellular functions, signaling pathways, and molecular effectors, known to be essential in the pathophysiological of IBD in these cells. Our preliminary data strongly indicate that a decrease in aPKC activity comparable to that observed in the animal model and in patients, is sufficient to trigger activation of the classic I?B pathway independently of TNFR. This observation opens the possibility that signaling downstream of aPKC may establish a negative feedback that keeps epithelial cells in an "inflamed" condition even if the original cytokine stimulaton is removed. If our hypothesis is correct, breaking this cycle may help to rapidly correct barrier defects and cytokine secretion by epithelial cells, which would be desirable in chronic intestinal inflammation. Moreover, since these pathways are specific to epithelial cells, understanding them may allow tissue-specific interventions. The mechanistic aspects and the consequences of this phenomenon will be studied in Aim 1. Our preliminary data also shows that a similar transient event occurs in epithelial wounds, suggesting the hypothesis that it may also be involved in the early stages of epithelial restitution, which will b tested in Aim 2. Finally, the molecular mechanisms studied in aims 1 and 2 will be analyzed in in the context of an animal model of colitis in Aim 3. Altogether the project is expeced to establish a totally novel signaling pathway, identify its normal function, and bring new, as ye unsuspected possible therapeutic targets to modulate the epithelial response to inflammation. PUBLIC HEALTH RELEVANCE: Inflammatory Bowel Disease is a multi-factorial aberrant response of the immune system that, among other effects, impacts on the layer of cells lining the intestinal lumen, the epithelium. This project studies a novel intracellular signaling pathway in the epithelium that counteracts the effects of inflammation. Importantly, if our hypothesis is correct, inhibition of this new pathway may contribute to the persistence of the effects of inflammation and may provide new unsuspected therapeutic opportunities.