The role of ErbB3-induced Pmp22 in intestinal barrier function

项目总结/摘要 肠上皮细胞在维持肠道健康和功能方面至关重要。它吸收营养， 水，同时也作为一个屏障，将管腔内容物和微生物群与身体的其他部分分开。 肠干细胞（ISCs）是这一屏障形成和再生的核心。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相关。 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，ErbB 3受体酪氨酸激酶在维持这种屏障中很重要， 因为肠上皮中ErbB 3缺失的小鼠（ErbB 3-IEKO）具有增加的肠通透性。 以前的研究表明ErbB 3及其配体Nrg-1β是上皮屏障的重要因子， 促进气道上皮细胞紧密连接的形成;然而，ErbB 3在维持气道上皮细胞紧密连接中的作用， 对肠屏障还知之甚少。我们发现，ErbB 3-IEKO小鼠的免疫应答显著减少， Pmp 22的表达，Pmp 22是上皮紧密连接的一种成分，最初被描述为在神经胶质瘤的髓鞘中。 周围神经在这个项目中，我将测试ErbB 3促进紧密连接形成的假设， 通过诱导Pmp 22维持在肠上皮中。在第一个目标中，我将定义 pmp 22在调节肠上皮细胞紧密连接中的作用。这将通过肠上皮细胞完成 Pmp 22通过转染敲低或过表达的细胞系，以及腹腔注射 Nrg-1β诱导Pmp 22表达。在第二个目标中，我将确定Pmp 22在细胞中是如何调节的。 通过使用小分子抑制ErbB 3下游途径， 上皮细胞由于ErbB 3需要异二聚化伴侣来进行信号传导，我还将确定 ErbB家族成员是EbB 3驱动的Pmp 22表达所必需的。拟议的研究将推进 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.