Mechanistic aspects of integrin-mediated Yersinia uptake

描述(由申请人提供)： 微生物的致病力在很大程度上取决于与宿主细胞和组织相互作用以促进定植和存活的毒力因子。这项建议的目的是更好地了解肠道致病性耶尔森氏菌表达的毒力因子利用宿主细胞因子促进疾病的机制。侵袭素是这些细菌产生的主要毒力因子之一，它通过与宿主细胞表面存在的β-1整合素结合，促进肠道上皮细胞的侵袭，在致病过程中发挥关键作用。这一建议验证了寄主中特定的整合素依赖的信号网络是耶尔森氏菌促进入侵的目标的假设。然而，尽管这些途径在最初的入侵过程中被激活，但在感染的后期阶段，它们被其他毒力因子的活性有效地颠覆，从而允许病原体在细胞外生长。这一假说的第二个方面是，整合素依赖的信号网络的组成部分最终克服了这些毒力因子的抑制作用，促进了细菌从肠道中的清除。为解决这些假设，制定了以下具体目标： 目的1：利用体外细胞培养模型，研究耶尔森菌摄取过程中巨噬细胞内整合素依赖的信号网络的分子组织和调控。 目的2：与耶尔森氏菌致病密切相关的整合素依赖的信号通路的一个组成部分是Src家族激酶。本研究的目的是利用Src基因敲除小鼠研究这些蛋白在耶尔森氏菌感染过程中的作用。 目的3：这些小鼠模型也将与一组含有特定细胞粘附素突变的耶尔森氏菌株一起用于探索耶尔森氏菌毒力因子与Src家族激酶在细菌入侵和定植过程中的功能关系。 这些研究的完成将有助于全面了解耶尔森氏菌致病的宿主细胞和微生物机制，并在此过程中提供对其他整合素依赖途径的洞察。

DESCRIPTION (provided by applicant): Microbial pathogenicity is largely determined by virulence factors that interface with host cells and tissues to promote colonization and survival. The goal of this proposal is to develop a better understanding of the mechanisms through which virulence factors expressed by enteropathogenic Yersiniae utilize host cell factors to promote disease. One of the major virulence factors produced by these bacteria is invasin, which plays a crucial role in pathogenicity by binding to beta-1 integrins present on the surface of host cells and facilitating invasion of the intestinal epithelium. This proposal tests the hypothesis that specific integrin dependent signaling networks in the host are targeted by the Yersiniae to promote invasion. Whereas these pathways are activated during the initial invasion process, however, they are effectively subverted at later stages in infection by the activities of other virulence factors, thus allowing for extracellular growth of the pathogen. A second facet of this hypothesis is that components of integrin-dependent signaling networks eventually overcome the inhibitory actions of these virulence factors and facilitate clearance of the bacteria from the intestine. The following specific aims have been developed to address these hypotheses: Aim 1: Using in vitro cell culture models, we propose to investigate the molecular organization and regulation of integrin-dependent signaling networks established in macrophages during the course ofYersinia uptake. Aim 2: One component of integrin-dependent signaling pathways that has been strongly implicated in aspects of Yersinia pathogenicity is the Src family kinases. This aim will explore the function of these proteins in the course of Yersinia infection with the use of Src family knockout mice. Aim 3: These mouse models will also be used, together with a panel of Yersinia strains that contain mutations in specific cellular adhesins, to explore the functional relationship between Yersinia virulence factors and Src family kinases during the course of bacterial invasion and colonization. Completion of these studies will help to generate a comprehensive understanding of the host cell and microbial mechanisms involved in Yersinia pathogenicity and, in the process, provide insight into other integrin-dependent pathways.