REGULATION OF EPITHELIAL PERMEABILITY BY GROWTH FACTORS

肠上皮细胞的屏障功能主要由 相邻细胞之间的紧密连接。 紧密连接渗透性是 由许多不同的因素调节，包括几种炎症因子， 介质，通过涉及细胞骨架变化的过程。 有越来越多的证据表明，增加连接渗透性， 在疾病的病因、进展和维持中发挥重要作用 慢性腹泻和炎症性肠病。 尤其是 连接渗透性的遗传性障碍可能使个体倾向于 克罗恩病。 为了了解增加的分子基础 结合渗透率，需要更好的基本理解 这种细胞旁途径的物理性质以及机制和因素 从而调节其渗透性。 此应用程序将识别角色 胰岛素和胰岛素样生长因子（IGFs）在 连接渗透性的调节。 使用单层培养的 分化的人结肠上皮细胞系T84，我们已经表明， 胰岛素和胰岛素样生长因子引起特异性、可逆且剂量依赖性的增加 连接渗透性。 使用分化的细胞的单层培养， 人结肠上皮细胞系T84，我们已经证明胰岛素和 IGFs可引起特异性、可逆性和剂量依赖性的连接蛋白表达增加， 磁导率 使用这个模型系统，我们将研究这些 肽类激素通过以下方式调节渗透性：1）识别受体 2）确定涉及的细胞内机制 在转导应答中;和3）识别细胞内的变化， 细胞骨架伴随着渗透性的变化。 然后我们将 确定IGF样肽的自分泌产生是否占 T84细胞不能保持高的跨上皮电阻， 在无血清培养基中生长。 实现这一目标将导致 确定的无血清培养基条件可用于检查生产， 培养的上皮细胞对其他生长因子的反应， 细胞因子 最后，我们将把我们的观察扩展到非致瘤性 细胞系培养和组织从兔实验 诱导结肠炎，以确定是否胰岛素样生长因子可能 以介导体内粘膜渗透性的增加。 这些实验 可能阐明参与调节的因素和机制 连接渗透性 这可能会导致一个更合理的方法， 了解病因和改善炎症治疗 肠道疾病。

The barrier function of intestinal epithelial cells is mediated largely by tight junctions between adjacent cells. Tight junctional permeability is regulated by a number of disparate factors including several inflammatory mediators, by processes which involve changes in the cellular cytoskeleton. There is accumulating evidence that increased junctional permeability could play an important role in the etiology, progression and maintenance of chronic diarrheal and inflammatory bowel diseases. In particular, an inherited disorder in junctional permeability may predispose individuals to Crohn's disease. In order to understand the molecular basis for increased junctional permeability, a better basic understanding is needed of the physical nature of this paracellular pathway and the mechanisms and factors which regulate its permeability. This application will identify the role and mechanism of insulin and insulin-like growth factors (IGFs) in regulation of junctional permeability. Using monolayer cultures of the differentiated human colonic epithelial cell line, T84, we have shown that insulin and IGFs cause a specific, reversible and dose dependent increase in junctional permeability. Using monolayer cultures of the differentiated human colonic epithelial cell line, T84, we have shown that insulin and IGFs cause a specific, reversible and dose dependent increase in junctional permeability. Using this model system, we will investigate how these peptide hormones regulate permeability by 1) identifying the receptors which mediate the effect; 2) identifying intracellular mechanisms involved in transducing the response; and 3) identifying changes in the cellular cytoskeleton which accompany changes in permeability. We will then determine whether autocrine production of IGF-like peptides accounts for the inability of T84 cells to retain high transepithelial resistance when grown in defined, serum-free media. Completion of this aim will result in defined, serum-free media conditions useful in examining the production and response of cultured epithelial cells to other growth factors and cytokines. Finally, we will extend our observations to non-tumorigenic cell lines in culture and to tissues from rabbits with experimentally induced colitis to determine whether insulin-like growth factors are likely to mediate increased mucosal permeability in vivo. These experiments are likely to elucidate the factors and mechanisms involved in regulating junctional permeability. This could lead to a more rational approach in understanding the etiology and in improving treatment for inflammatory bowel disease.