Structure function studies in intestinal epithelial JAM

描述(申请人提供)：本提案的一个中心主题是基于不断发展的概念，即紧密连接(TJ)蛋白的功能不是简单地作为静态的物理屏障形成元件，而是调节肠道上皮细胞内关键的动态平衡功能的信号中心。这一概念与在人类中发现的与肠道稳态失调相关的疾病，如溃疡性结肠炎和克罗恩病，TJ蛋白表达的改变与肠道上皮屏障功能缺陷和广泛的粘膜溃疡/损伤有关。这项建议的目标集中在阐明紧密连接蛋白JAM-A信号如何控制上皮屏障和细胞迁移的基本机制。它将专门专注于识别与JAM-A相连的新的近端信号元件，这些元件在连接组装和稳定状态期间调节屏障(目标1)。它还将侧重于阐明JAM-A如何通过在蛋白质运输和小分子水平上影响β1整合素动态来调节细胞迁移 GTP酶信号转导。我们已经证明，JAM-A介导的细胞迁移和屏障的调节依赖于同一细胞内顺式构型中JAM-A的二聚化。在这项提案的目标3中，我们将扩展这些重要的发现，以确定JAM-A在反式调节细胞之间的二聚化的作用，以及这种相互作用是否在调节细胞迁移和屏障方面发挥作用。从这些研究中获得的知识不仅将为TJ调节渗透性、迁移和增殖的自外向内信号机制提供新的曙光，而且还可能为从增强疫苗/药物输送到伤口愈合/抗炎或抑制癌症进展的多种应用的治疗靶点提供新的想法。

DESCRIPTION (provided by applicant): A central theme of this proposal is based on the evolving concept that tight junction (TJ) proteins do not function simply as static, physical barrir forming elements but as signaling centers that regulate critical homeostatic functions within intestinal epithelial cells. This concept is consistent with findings in humans that have condition associated with dysregulated intestinal homeostasis such as ulcerative colitis and Crohn's Disease where altered TJ protein expression is associated with defective intestinal epithelial barrier function and extensive mucosal ulceration/wounding. The goal of this proposal is centered on elucidating fundamental mechanisms of how the tight junction protein JAM-A signals to control epithelial barrier and cell migration. It will specifically focus on identifyingnovel proximal signaling elements linked to JAM-A that regulate barrier during junctional assembly and during the steady state (Aim 1). It will also focus on elucidating how JAM-A regulates cell migration through effects on beta 1 integrin dynamics at the level of protein trafficking and small GTPase signaling. We have demonstrated that JAM-A mediated regulation of cell migration and barrier are dependent on dimerization of JAM-A in a cis configuration within the same cell. In aim 3 of this proposal, we will extend these important findings to determine the role of dimerization of JAM-A between cells in trans and if such interactions play a role in regulating cell migration and barrier. Knowledge gained from these studies will not only shed new light into mechanisms of outside-in signaling at the TJ that regulate permeability, migration and proliferation, but may also provide new ideas for therapeutic targets with diverse applications ranging from enhanced vaccine/drug delivery to wound healing/anti-inflammation or inhibition of cancer progression.