INTESTINAL MECHANISMS OF C DIFFICILE TOXINS

描述：艰难梭菌是一种常见且无情的病原体。 这是相当大比例传染性疾病的基础 胃肠道疾病在美国和其他国家。虽然 艰难梭菌本身很少致死，对健康构成重大风险， 特别是在那些年纪很小或很老的人中，因为 它的坚韧，或复发和复发的倾向。一个完整的 了解艰难梭菌的致病机制将有 对公共卫生和与医疗保健相关的经济产生重要影响； 因此，这个问题当然值得关注。此应用程序 是为了续签由首席调查员为 好几年了。 艰难梭菌通过精心制作两种独特的毒素而臭名昭著，标记为A 和B.这些毒素通过与细胞结合进入结肠细胞 表面受体；此后，内吞作用促进细胞进入和 随后细胞内机械的衰减。具体地说， 毒素A和B的细胞内靶标似乎是GTP结合的Rho 调节肌动蛋白细胞骨架的蛋白质。很大一部分 我们对这些过程的理解是根据 在过去的十年里，他们一直在调查实验室。此应用程序建议 从三个不同的方面继续这项调查。第一, 将进行毒素A和B受体的纯化和克隆 使用人体组织。这个实验室最近进行了类似的研究 在兔身上工作，证明蔗糖酶-异麦芽糖酶是主要的 该物种中毒素A的细胞表面受体。刻画人物形象 人类受体是这项工作的合理延伸。第二，上皮性 毒素结合激活的细胞转导机制将被确定。 在这一系列实验中，调查人员将延长他们的 毒素结合对结肠细胞影响的初步观察 钙离子通量，特别强调蛋白酪氨酸激酶的作用 和蛋白激酶C在这一过程中。第三，毒素产生的途径 将对其在结肠细胞内的作用部位进行调查。 将特别强调受体介导的内吞作用和 毒素内化过程中的囊泡运输。

DESCRIPTION: Clostridium difficile is a common and relentless pathogen which is the basis for a substantial proportion of infectious gastrointestinal disease in the United States and other countries. Although seldom lethal by itself, C. difficile represents a significant health risk, particularly among those in their very early or very elderly years because of its tenacity, or propensity for relapse and recurrence. A complete understanding the pathogenetic mechanisms of C. difficile would have an important impact on the public health and on healthcare-related economics; as such, the problem is certainly worthy of the attention. This application is for the renewal of an award held by the principal investigator for several years. C. difficile reeks its havoc by elaboration of two unique toxins, labelled A and B. These toxins gain entrance into colonocytes by binding to cell surface receptors; thereafter, endocytosis facilitates cellular entry and subsequent attenuation of intracellular machinery. Specifically, the intracellular targets of toxins A and B appear to be the GTP-binding Rho proteins which regulate the actin cytoskeleton. A substantial portion of our understanding of these processes is consequent to data collected by the investigator's laboratory over the past decade. This application proposes to continue this investigation along three distinct fronts. First, purification and cloning of the receptors for Toxin A and B will be carried out using human tissue. This laboratory has recently carried out similar work in the rabbit, demonstrating that sucrase-isomaltase is the primary cell surface receptor for Toxin A in this species. Characterization of the human receptors is a logical extension of this work. Second, epithelial cell transduction mechanisms activated by toxin binding will be determined. In this series of experiments, the investigators will extend their preliminary observations regarding the effect of toxin binding on colonocyte Ca flux, with particular emphasis on the roles of protein tyrosine kinase and protein kinase C in this processes. Third, the means by which toxins gain access to its site of action within colonocytes will be investigated. Specific emphasis will be placed on receptor mediated endocytosis and vesicular transport in toxin internalization.