Genetic analysis of innate immunity using C. elegans

描述(由申请人提供)：本提案的目的是对先天免疫的分子机制提供见解。正向和反向遗传学研究已经发现线虫和哺乳动物防御反应所需的信号通路，这表明尽管线虫和哺乳动物之间存在巨大的进化鸿沟，但防御反应的一些潜在机制可能是相似的。我们使用了一组对病原体具有超敏性的线虫突变体来定义一个防御反应通路，该通路涉及CED-3程序性细胞死亡途径和由PMK-1基因编码的哺乳动物p38丝裂原活化蛋白激酶(MAPK)的线虫同源物。此外，在线虫中，脂多糖(LPS)被发现作为病原体相关的分子模式(PAMP)，触发依赖CED/MAPK的程序性细胞死亡。我们的初步结果表明，CED-1蠕虫对肠球菌是超敏的，CED-1是有效清除凋亡细胞所必需的，并与CED-3合作促进细胞死亡，编码哺乳动物CD91受体的同源基因，该受体通过识别热休克蛋白(包括HSP90)参与诱导先天性和获得性免疫反应。此外，为了建立哺乳动物和线虫天然免疫之间的相似性，我们研究了脂多糖暴露小鼠的表达谱，以确定PAMP应答基因，并分析了线虫同源基因在防御反应中的作用。三个内毒素应答基因的线虫突变体对细菌病原体的敏感性进行了测试，其中两个被发现缺乏防御反应。其中一个突变体是daf-21(P673)，它在哺乳动物HSP90的线虫同源物中存在错义突变。首先，我们建议继续我们涉及ce基因的初步研究，以确定这些基因触发防御反应的机制，以及细胞死亡与病原体易感性之间的关系。我们还将进一步研究DAF-21/HSP90在防御反应中的作用，并剖析其与CED-1/CD91通路的相互作用。最后，我们建议使用生物信息学、功能基因组学和比较基因组学来识别和表征线虫和哺乳动物天然免疫所需的防御相关基因。

DESCRIPTION (provided by applicant): The goal of this proposal is to provide insights into the molecular mechanism of innate immunity. Forward and reverse genetic studies have led to the identification of C. elegans signaling pathways that are required for defense response in both nematodes and mammals, suggesting that despite the vast evolutionary gulf between nematodes and mammals, some of the underlying mechanisms of defense response may be similar. We have used a set of C. elegans mutants hypersusceptible to pathogens to define a defense response pathway that involves the CED-3 programmed cell death pathway and the C. elegans homolog of the mammalian p38 mitogen-activated protein kinase (MAPK) encoded by the pmk-1 gene. Also, lipopolysaccharide (LPS) was found to act as a pathogen-associated molecular pattern (PAMP) that triggers a CED/MAPK-dependent programmed cell death in C. elegans. Our preliminary results indicate that ced-1 worms are hypersusceptible to S. enterica, ced-1, that is required for efficient clearance of apoptotic cells and cooperates with ced-3 to promote cell death, encodes a homolog of the mammalian CD91 receptor which has been involved in the elicitation of innate and adaptive immune responses by recognizing heat shock proteins, including HSP90. In addition, to establish parallels between innate immunity in mammals and nematodes, we have studied the expression profile of mice exposed to LPS to identify PAMPresponsive genes and the role of the C. elegans homologs in defense response was analyzed. Three C. elegans mutants in LPS-responsive genes were tested for their susceptibility to bacterial pathogens and two of them were found to be deficient in defense response. One of the mutants is daf-21(p673), which has a missense mutation in the C. elegans homolog of mammalian hsp90. First, we propose to continue our preliminary studies involving ced genes to determine the mechanisms by which these genes trigger defense response and the relationship between cell death and susceptibility to pathogens. We will also further characterize the role of DAF-21/HSP90 in defense-response and dissect its interaction with the CED-1/CD91 pathway. Finally, we propose to use bioinformatics and functional and comparative genomics to identify and characterize defense-related genes required for innate immunity in both nematodes and mammals.