Regulation of Innate Immunity by Virulence Factors

描述（由申请人提供）：本探索性提案的目标是解决秀丽隐杆线虫是否可以用于在整个动物水平上提供对细菌毒力因子调节宿主基因表达以抑制先天免疫的机制的理解的见解。许多细菌病原体，包括潜在的生物战病原体，都有共同的策略来感染和定植各种动物。这表明毒力因子与其宿主靶点之间的相互作用有一个古老的起源，并开启了使用替代的非脊椎动物模型来加速病原体和宿主信号通路的识别和表征的可能性，这些信号通路可以作为干预的目标。我们一直在用遗传方法研究秀丽隐杆线虫模型遗传生物中细菌毒力因子与其靶点之间的相互作用。利用正向和反向遗传方法，我们已经确定了秀丽隐杆线虫和哺乳动物发病所需的多种沙门氏菌毒力相关基因，包括与沙门氏菌III型分泌系统（TTSS）相关的基因，该系统致力于输出效应蛋白，通过特异性干扰宿主细胞过程促进细菌发病。我们已经证明，当在秀丽隐杆线虫肠细胞中表达时，效应蛋白SptP通过靶向p38 MARK信号通路使动物更容易感染肠链球菌，p38 MARK信号通路对哺乳动物的先天免疫也很重要。本课题的具体目的是：1)利用微阵列技术进行转录谱分析，鉴定受肠链球菌毒力因子肠道表达调控的特异性先天免疫基因。2)利用秀丽隐杆线虫RNAi文库，鉴定在失活时增强或抑制秀丽隐杆线虫因毒力因子表达而增加的肠球菌敏感性表型的基因。3)阐明Aims 1和Aims 2中鉴定的基因对秀丽隐杆线虫先天免疫通路在哺乳动物中保守的作用机制。

DESCRIPTION (provided by applicant): The goal of this exploratory proposal is to address the question of whether C. elegans can be used to provide insights into the understanding of the mechanisms by which bacterial virulence factors regulate host gene expression to inhibit innate immunity at the whole animal level. Many bacterial pathogens, including potential agents of biological warfare, share strategies to infect and colonize a wide range of animals. This suggests an ancient origin for the interactions between virulence factors and their targets in the host, and opens the possibility of using alternative non-vertebrate models to accelerate the identification and characterization of both pathogen and host signaling pathways that can be targeted for intervention. We have been using a genetic approach to study the interaction between bacterial virulence factors and their targets in the model genetic organism Caenorhabditis elegans. Using forward and reverse genetic approaches, we have identified a variety of Salmonella virulence-related genes required for pathogenesis in C. elegans and mammals, including genes related to the Salmonella type III secretion system (TTSS) dedicated to export effector proteins that facilitate bacterial pathogenesis by specifically interfering with host cellular processes. We have shown that when expressed in the C. elegans intestinal cells, effector protein SptP makes the animals more susceptible to S. enterica by targeting a p38 MARK signaling pathway that is also important for innate immunity in mammals. The Specific Aims of this proposal are: 1) Use microarrays to carry out transcriptional profiling analysis to identify specific innate immunity genes that are regulated by the intestinal expression of S. enterica virulence factors. 2) Use C. elegans RNAi libraries to identify genes which when inactivated enhance or suppress the increased susceptibility to S. enterica phenotype imposed by the expression of virulence factors in C. elegans. 3) Elucidate the mechanism by which the genes identified in Aims 1 and 2 contribute to C. elegans innate immunity pathways conserved in mammals.