Structure function studies in intestinal epithelial JAM

摘要 这一提议有力地支持了紧密连接相关蛋白为关键的新概念 肠道上皮内环境平衡的调节器。现在人们意识到，紧密连接(TJ) 蛋白质不是静态的屏障形成单位，而是作为动态信号中心来微调许多 关键的上皮细胞功能包括增殖、迁移和细胞存活。的确， 溃疡性结肠炎和克隆氏病等炎症性疾病与肠漏有关， 上皮细胞增殖和损伤的伤口愈合/粘膜溃疡，部分与改变有关 紧密连接蛋白的表达。与这个项目有关，我们有令人信服的证据表明 TJ相关CTX蛋白、连接黏附分子A(JAM-A)和类CAR的重要性 膜蛋白(CLMP)，在调节粘膜动态平衡中起互补作用 促进上皮屏障功能，下调IEC增殖反应。有趣的是，我们 在炎症条件下观察到上皮细胞-细胞接触中JAM-A减少，而 相反，CLMP的表达增强，表明CTX依赖的协调微调 上皮细胞在动态平衡状态下的反应。这项提案的目标集中在 JAM-A和CLMP调节关键上皮屏障的基本机制 功能和细胞增殖。在目标1和目标2中，我们将扩大初步调查结果，以确定新的 控制JAM-A介导的屏障和上皮细胞增殖调节的信号元件， 分别进行了分析。在目标3中，利用新的可诱导的、组织靶向的基因敲除小鼠，我们将首次定义 时间，CLMP在调节上皮屏障功能和增殖中的作用。建议进行的研究 不仅为TJ调节通透性的内外信号机制提供了新的线索 和增殖，但也可能为具有不同应用的治疗靶点提供新的想法 从加强疫苗/药物输送到伤口愈合/抗炎或抑制癌症 进步。

ABSTRACT This proposal lends strong support to the new concept of tight junction associated proteins as key regulators of epithelial homeostasis in the intestine. It is now appreciated that tight junction (TJ) proteins are not static barrier forming units, but act as dynamic signaling centers to fine tune many critical epithelial cellular functions ranging including proliferation, migration and cell survival. Indeed, inflammatory conditions such as ulcerative colitis and crohns disease are associated with a leaky gut, epithelial proliferation and impaired wound healing/mucosal ulceration that is, in part, related to altered expression of tight junction proteins. Pertinent to this project, we have compelling evidence of the importance of TJ associated CTX proteins, junctional adhesion molecule A (JAM-A) and CAR Like Membrane Protein (CLMP), that play complementary roles in the regulation of mucosal homeostasis by promoting epithelial barrier function and downregulating IEC proliferative responses. Intriguingly, we have observed reduced JAM-A in epithelial cell-cell contacts under inflammatory conditions while CLMP expression, in contrast, is enhanced, suggesting coordinated fine tuning of CTX-dependent epithelial responses under conditions of perturbed homeostasis.The goal of this proposal is centered on elucidating fundamental mechanisms of how JAM-A and CLMP regulate crucial epithelial barrier function and cellular proliferation. In Aims 1 and 2, we will extend preliminary findings that identify new signaling elements controlling JAM-A-mediated regulation of barrier and epithelial proliferation, respectively. In aim 3, with new inducible, tissue targeted knockout mice, we will define, for the first time, the role of CLMP in regulation of epithelial barrier function and proliferation. The proposed studies will not only shed new light into mechanisms of outside-in signaling at the TJ that regulate permeability 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.