Role of CD98 in Intestinal Permeability

描述（由申请人提供）：主要上皮渗透性屏障由同型和异型细胞/细胞相互作用和细胞/细胞外基质（ECM）相互作用触发的级联事件控制和调节。自从开始这项研究以来，我们已经证明了CD 98，一种II型膜糖蛋白，与肠上皮细胞中的氨基酸转运蛋白共价连接，形成异二聚体。在肠上皮中，异二聚体与21-整合素和细胞间粘附分子1（ICAM-1）结合，在极化的肠上皮细胞的基底外侧膜中形成大分子复合物。CD 98的细胞外C-末端结构域含有在ECM蛋白/蛋白相互作用中具有作用的PDZ结合结构域。在肠道炎症期间，上皮细胞CD 98上调由促炎细胞因子干扰素3（IFN-3）介导。我们的总体假设是，大分子复合物可能控制重要的功能，如细胞/细胞和细胞/基质相互作用。本提案的第一个目的是研究上皮CD 98表达对体外和体内肠屏障功能的功能影响。具体而言，我们将确定影响肠上皮细胞通透性屏障的特定分子CD 98结构域。其次，我们将研究CD 98在上皮/T细胞和上皮/基质相互作用中的作用。此外，我们将确定负责这些相互作用的CD 98分子结构域。最后，我们将使用体内方法研究在T淋巴细胞中表达的CD 98的作用。该项目将涉及各种生物化学、分子、体外和体内方法。体外实验将使用肠上皮细胞系Caco 2-BBE和免疫细胞系Jurkat在分子和生化水平上研究CD 98在肠道炎症中的表达/功能。体内实验将使用携带条件性CD 98基因的小鼠和实验性结肠炎小鼠，以确认和开发设计治疗策略所需的关键信息，以改善肠道炎症状况，包括IBD。在美国，超过一百万的成人和儿童患有炎症性肠病。新的治疗策略的基础上更好地了解炎症性肠病的发病机制，将改善这种疾病的患者的临床护理。公共卫生相关性：尽管在过去的十年中，在理解IBD的遗传、环境和免疫失调方面取得了重大进展，但对IBD的发病机制知之甚少。据设想，这项研究将确定CD 98在肠道炎症中的功能作用的分子机制，并启动治疗策略，以改善肠道炎症性疾病，包括IBD。

DESCRIPTION (provided by applicant): The major epithelial permeability barriers are controlled and regulated by a cascade of events triggered by homotypic and heterotypic cell/cell interactions and cell/extracellular matrix (ECM) interactions. Since starting this research, we have demonstrated that CD98, a type II membrane glycoprotein, is covalently linked to an amino-acid transporter in intestinal epithelial cells to form a heterodimer. In intestinal epithelia, the heterodimer is associated with 21-integrin and intercellular adhesion molecular 1 (ICAM-1) to form a macromolecular complex in the basolateral membranes of polarized intestinal epithelial cells. The extracellular C-terminal domain of CD98 contains a PDZ-binding domain that has a role in ECM protein/protein interactions. Epithelial CD98 up-regulation is mediated by the pro-inflammatory cytokine interferon 3 (IFN-3) during intestinal inflammation. Our overall hypothesis is that the macromolecular complex may control important functions such as cell/cell and cell/matrix interactions. The first aim of this proposal is to investigate the functional effects of epithelial CD98 expression on in-vitro and in-vivo intestinal barrier function. Specifically, we will identify the specific molecular CD98 domains that affect intestinal epithelia permeability barriers. Second, we will investigate the role of CD98 in epithelial/T cell and epithelial/matrix interactions. Furthermore, we will identify the CD98 molecular domains that are responsible for these interactions. Finally, we will examine the role of CD98 that is expressed in T lymphocytes using an in-vivo approach. The project will involve a variety of biochemical, molecular, in vitro and in vivo approaches. In vitro experiments will use intestinal epithelial cell line Caco2-BBE and immune cell line Jurkat to investigate at the molecular and biochemical levels the expression/function of CD98 in intestinal inflammation. In vivo experiments will use mice that harbored a conditional CD98 gene and experimental colitis mice in order to confirm and develop the key information needed to design therapeutic strategies to ameliorate intestinal inflammatory conditions including IBD. Over one million adults and children in the U.S, suffer from inflammatory bowel disease. New therapeutic strategies based on a better understanding of the pathogenesis of IBD will improve the clinical care of patient with this disorder. PUBLIC HEALTH RELEVANCE: Even though major advances have been made in the past decade with respect to understanding the genetics, environmental and immune dysregulation in IBD, the etiopathogenesis of IBD is poorly understood. It is envisaged that this investigation will define the molecular mechanisms underlying the functional role of CD98 in intestinal inflammation and initiate therapeutic strategies to ameliorate intestinal inflammatory conditions including IBD.