The role of ErbB3-induced Pmp22 in intestinal barrier function

项目摘要/摘要 肠道上皮在维持肠道健康和功能方面起着至关重要的作用。它吸收营养物质， 水，同时也是将管腔内容物和微生物区系与身体其他部分隔开的屏障。 肠道干细胞(ISCs)是这种屏障形成和再生的中心。屏障功能障碍是 与炎症性肠病、乳糜泻和肠易激综合征等疾病有关。 尽管它在肠道疾病中很重要，但目前还没有针对屏障的治疗方法。 我的初步数据表明，ErbB3受体酪氨酸激酶在维持这一屏障方面起着重要作用， 作为肠道上皮ErbB3缺失的小鼠(ErbB3-IEKO)，肠道通透性增加。 以前的研究表明，ErbB3及其配体NRG-1β与NRG-1β一样，是上皮屏障的重要因素 促进呼吸道上皮细胞紧密连接的形成；然而，ErbB3的S在维持呼吸道上皮细胞紧密连接中的作用 肠道屏障目前还知之甚少。我们发现ErbB3-IEKO小鼠明显减少了 PMP22的表达，PMP22是上皮紧密连接的一种成分，最初被描述为在骨髓鞘中的表达 周围神经。在这个项目中，我将测试ErbB3促进紧密连接形成和 通过诱导PMP22维持肠上皮细胞的功能。在第一个目标中，我将定义 PMP22在调节肠上皮紧密连接中的作用。这将通过肠道上皮细胞完成 携带PMP22基因的细胞系通过转基因被击倒或过表达，并给小鼠腹腔注射 NRG-1β诱导PMP22表达。在第二个目标中，我将确定PMP22如何在 肠上皮细胞中ErbB3下游小分子抑制通路的利用 上皮细胞。因为ErbB3需要异二聚化伙伴来进行信令，所以我还将确定哪一个 ErbB家族成员是EbB3驱动的PMP22表达所必需的。拟议的研究将会取得进展 了解肠道屏障是如何形成和调节的，并最终将致力于发展 屏障维持作为肠道炎症性疾病的治疗靶点。

PROJECT SUMMARY/ABSTRACT The intestinal epithelium is critical in the maintenance of gut health and function. It absorbs nutrients and water, while also acting as a barrier to separate luminal contents and the microbiota from the rest of the body. Intestinal stem cells (ISCs) are central to the formation and regeneration of this barrier. Barrier dysfunction is associated with diseases such as inflammatory bowel disease, celiac disease, and irritable bowel syndrome. Despite the importance it has in intestinal disorders, there are currently no treatments that target the barrier. My preliminary data suggest that the ErbB3 receptor tyrosine kinase is important in maintenance of this barrier, as mice with ErbB3 deletion in the intestinal epithelium (ErbB3-IEKO) have increased intestinal permeability. Previous studies implicated ErbB3 and its ligand Nrg-1β as important factors in epithelial barriers, as Nrg-1β promotes tight junction formation in airway epithelial cells; however, ErbB3’s role in maintenance of the intestinal barrier is as yet poorly understood. We find that ErbB3-IEKO mice have markedly reduced expression of Pmp22, a component of epithelial tight junctions originally described as in the myelin sheath of peripheral nerves. In this project, I will test the hypothesis that ErbB3 promotes tight junction formation and maintenance in the intestinal epithelium through induction of Pmp22. In the first aim, I will define the role of Pmp22 in regulating tight junctions in the intestinal epithelium. This will be done through intestinal epithelial cell lines with Pmp22 knocked down or overexpressed via transfection, and mice given intraperitoneal injection of Nrg-1β to induce Pmp22 expression. In the second aim, I will determine how Pmp22 is regulated in the epithelium through the use of the small molecules inhibiting pathways downstream of ErbB3 in intestinal epithelial cells. Because ErbB3 requires a heterodimerization partner for signaling, I will also determine which ErbB family members are required for EbB3-driven Pmp22 expression. The proposed research will advance knowledge of how the intestinal barrier is formed and regulated, and ultimately will work towards developing barrier maintenance as a therapeutic target for inflammatory diseases in the gut.