A NOVEL ROLE FOR PTPN2 IN INTESTINAL EPITHELIAL BARRIER REGULATION

描述（由申请人提供）：肠道通透性增加在许多慢性肠道炎症条件中起着至关重要的作用，包括1型糖尿病（T1D），乳糜泻，以及克罗恩病（CD）和溃疡性结肠炎（UC），统称为炎症性肠病（IBD）。超过140万美国人患有炎症性肠病。虽然IBD的确切病因尚不清楚，但有大量证据表明，肠上皮层的通透性缺陷在IBD的发展中起着重要作用。肠上皮是一层细胞，它形成了肠道细菌（肠道微生物群）与身体其他部分之间的界面。在炎症期间，上皮暴露于高水平的炎症介质，如干扰素-g （IFNg）。这些介质激活信号通路，改变上皮的各种功能，如屏障维持。这些信号的终止主要是由磷酸酶的活性介导的。其中一种磷酸酶，蛋白酪氨酸磷酸酶非受体2型（PTPN2），在非上皮细胞中负向调节IFNg信号。然而，关于PTPN2在肠上皮中的功能知之甚少。最近，PTPN2基因的单核苷酸多态性（SNP）被确定为与克罗恩病、UC、T1D和乳糜泻相关的遗传标记。因此，这些疾病具有共同的基因关联和肠道通透性升高。我们最近发现了一种全新的PTPN2参与上皮屏障功能的调节。因此，本课题的具体目的是了解PTPN2在调节肠道屏障功能中的作用，并确定PTPN2如何参与慢性肠道炎症性疾病的发病机制。这将通过三个具体目标来解决。目的1将通过确定PTPN2如何限制炎症因子引起的肠上皮屏障功能障碍来研究PTPN2如何调节炎症诱导的肠屏障功能障碍。目的2将确定炎症细胞因子如何调节PTPN2的表达、活性和细胞定位。目的3将利用PTPN2缺陷小鼠，在体内确定PTPN2如何调节肠道通透性。预期结果和影响：这些研究将为PTPN2在肠屏障功能调节中的作用、炎症介质对PTPN2表达和活性的影响以及PTPN2缺失对上皮细胞因子信号传导的功能影响提供基础见解。在更广泛的范围内，我们将发现一个基因（PTPN2）和一种病理生理现象（肠道通透性增加）之间的统一联系，它们都从根本上参与了乳糜泻、UC、1型糖尿病和乳糜泻。这些研究也可能为表达PTPN2 SNP的IBD患者确定新的诊断和治疗方法。

DESCRIPTION (provided by applicant): Increased intestinal permeability plays a crucial role in a number of chronic intestinal inflammatory conditions including Type 1 Diabetes (T1D), celiac disease, as well as Crohn's disease (CD) and ulcerative colitis (UC), collectively referred to as inflammatory bowel disease (IBD). More than 1.4 million Americans suffer from IBD. While the exact cause(s) of IBD are unknown, there is considerable evidence that a permeability defect in the intestinal epithelial layer plays a major role in the development of IBD. The intestinal epithelial lining is a single layer of cells that forms the interface between the bactera that reside in the intestine (intestinal microbiota), and the rest of the body. During inflammation the epithelium is exposed to high levels of inflammatory mediators such as interferon-g (IFNg). These mediators activate signaling pathways that alter various functions of the epithelium, such as barrier maintenance. Termination of these signals is mediated largely by the activity of phosphatases. One such phosphatase, protein tyrosine phosphatase non-receptor type 2 (PTPN2), negatively regulates IFNg signaling in non-epithelial cells. However, little is known about the function of PTPN2 in the intestinal epithelium. Recently, single nucleotide polymorphisms (SNP) in the PTPN2 gene have been identified as a genetic marker associated with Crohn's disease, UC, T1D and celiac disease. Thus, these diseases share a common gene association and an elevation in intestinal permeability. We have recently identified a completely novel involvement of PTPN2 in the regulation of epithelial barrier function. Therefore, the specific objectives of this proposal are to understand the role of PTPN2 in regulating intestinal barrier function, and to identify how PTPN2 may be involved in the pathogenesis of chronic intestinal inflammatory diseases. This will be addressed in three specific aims. Aim 1 will investigate how PTPN2 modulates inflammation-induced intestinal barrier dysfunction by determining how PTPN2 restricts intestinal epithelial barrier dysfunction caused by inflammatory cytokines. Aim 2 will identify how the expression, activity and cellular localization of PTPN2 are regulated by inflammatory cytokines. Aim 3 will identify how PTPN2 regulates intestinal permeability in vivo using PTPN2-deficient mice. Expected Outcomes & Impact: These studies will provide fundamental insights into the role of PTPN2 in the regulation of intestinal barrier function, the effect of inflammatory mediators on PTPN2 expression and activity, and the functional consequences of a loss of PTPN2 on epithelial cytokine signaling. On a broader scale, we will identify a unifying link for a gene (PTPN2) and a pathophysiological phenomenon (increased intestinal permeability) that are both fundamentally involved in CD, UC, Type 1 diabetes and celiac disease. These studies may also identify new diagnostic and treatment approaches for IBD patients expressing a PTPN2 SNP.