Role of CD98 in Intestinal Permeability

描述(由申请人提供)：主要的上皮通透性屏障由一系列由同型和异型细胞/细胞相互作用和细胞/细胞外基质(ECM)相互作用触发的事件控制和调节。自从开始这项研究以来，我们已经证明了CD98，一种II型膜糖蛋白，与肠上皮细胞中的氨基酸转运体共价连接，形成异源二聚体。在肠上皮细胞中，异源二聚体与21-整合素和细胞间黏附分子-1(ICAM-1)结合，在极化的肠上皮细胞的基侧膜上形成大分子复合体。CD98的胞外C末端结构域含有一个PDZ结合域，在ECM蛋白/蛋白相互作用中发挥作用。在肠道炎症过程中，上皮CD98的上调是由促炎细胞因子干扰素-3(IFN-3)介导的。我们的总体假设是，大分子复合体可能控制重要的功能，如细胞/细胞和细胞/基质相互作用。本研究的第一个目的是研究上皮细胞CD98表达对体外和体内肠道屏障功能的影响。具体地说，我们将确定影响肠上皮细胞通透性屏障的特定分子CD98结构域。其次，我们将研究CD98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CD98分子结构域。最后，我们将使用体内方法研究CD98在T淋巴细胞中表达的作用。该项目将涉及多种生化、分子、体外和体内方法。体外实验将利用肠上皮细胞系Caco 2-BBE和免疫细胞系Jurkat，从分子和生化水平研究CD98在肠道炎症中的表达和功能。体内实验将使用携带条件CD98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以改善包括IBD在内的肠道炎症状况所需的关键信息。在美国，有100多万成年人和儿童患有炎症性肠病。基于对IBD发病机制的更好理解，新的治疗策略将改善该疾病患者的临床护理。与公共卫生相关：尽管在过去十年中，在了解IBD的遗传学、环境和免疫失调方面取得了重大进展，但对IBD的病因还知之甚少。预计这项研究将确定CD98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包括IBD在内的肠道炎症状况。

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.