A novel role for PTPN2 in intestinal epithelial barrier regulation

项目摘要 肠道通透性增加在许多慢性肠道炎症中起着关键作用。 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IBD。 虽然IBD的确切原因(S)尚不清楚，但有相当多的证据表明， 肠上皮细胞(IEC)层在IBD的发生发展中起重要作用。肠上皮衬里 是构成驻留在肠道(肠道)的细菌之间的界面的单层细胞 微生物区系)，以及身体的其他部分。在炎症过程中，上皮细胞暴露在高水平的 炎症介质，如干扰素-(干扰素)。这些介体激活信号通路，从而改变 上皮细胞的各种功能，如屏障维持。这些信号的终止是由 主要是由磷酸酶的活性决定的。一种这样的磷酸酶，蛋白酪氨酸磷酸酶，非受体类型 2(PTPN_2)，负调控非上皮细胞干扰素信号转导。然而，人们对此知之甚少 PTPN2在肠上皮细胞中的功能。PTPN2基因的单核苷酸多态(SNP)具有 已被确认为与克罗恩病、UC、T1D和乳糜泻相关的遗传标记。因此，这些 疾病有共同的基因关联和肠道通透性升高。我们已经确定了一个 PTPN2在调节上皮屏障功能中的全新参与。因此，具体的 这项建议的目的是更好地了解PTPN2功能丧失突变是如何改变的 磷酸化信号网络对肠道屏障功能的影响，如果这一点可以通过一种 临床有效的治疗剂。这将在三个具体目标中得到解决。目标1：确定 PTPN2功能丧失导致上皮屏障缺陷的分子机制目的2：PTPN2是一种 JAK-STAT炎症信号通路的负调控因子。我们将调查JAK抑制剂， 托法替尼通过抑制JAK-STAT通路纠正PTPN2功能丧失的后果 通常受到PTPN2的限制。目的3：确定PTPN2磷酸酶活性的丧失如何改变其“磷酸化”。 IEC中的“相互作用体”以及这对紧密连接蛋白的磷酸调节有何影响。预期 结果和影响：这些研究不仅将建立一个更准确的机制理解 功能缺失的PTPN2突变对屏障功能调节和相关信号的影响 但也将确定一种可能的治疗方法来解决这些缺陷。

Project Summary 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 cell (IEC) 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 bacteria 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- (IFN). 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 IFN signaling in non-epithelial cells. However, little is known about the function of PTPN2 in the intestinal epithelium. Single nucleotide polymorphisms (SNP) in the PTPN2 gene have been confirmed 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 identified a completely novel involvement of PTPN2 in the regulation of epithelial barrier function. Therefore, the specific objectives of this proposal are to better understand how PTPN2 loss-of-function mutations alter phosphorylation signaling networks impacting upon intestinal barrier function, and if this can be corrected by a clinically-effective therapeutic agent. This will be addressed in three specific aims. Aim 1: Determine the molecular mechanisms causing epithelial barrier defects due to PTPN2 loss of function Aim 2: PTPN2 is a negative regulator of JAK-STAT inflammatory signaling pathways. We will investigate if the JAK inhibitor, Tofacitinib can correct the consequences of PTPN2 loss of function through inhibiting JAK-STAT pathways normally restricted by PTPN2. Aim 3: Identify how loss of PTPN2 phosphatase activity alters its “phospho- interactome” in IEC and how does this impact upon tight junction protein phosphoregulation. Expected Outcomes & Impact: These studies will not only build a more accurate mechanistic understanding of the consequences of loss-of-function PTPN2 mutations for barrier function regulation and associated signaling networks, but will also identify a possible therapeutic approach to resolve these defects.