Genetic analysis of innate immunity using C. elegans

描述（由申请人提供）：本提案的目标是深入了解先天免疫的分子机制。正向和反向遗传研究已经确定了线虫和哺乳动物防御反应所需的秀丽隐杆线虫信号通路，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。我们使用一组对病原体敏感的秀丽隐杆线虫突变体来定义一个防御反应途径，该途径涉及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）的秀丽隐杆线虫同源物。此外，脂多糖（LPS）被发现作为病原体相关分子模式（PAMP）触发线虫中CED/ mapk依赖性程序性细胞死亡。我们的初步结果表明，ced-1蠕虫对肠链球菌敏感，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受体的同源物，该受体通过识别热休克蛋白（包括HSP90）参与先天和适应性免疫反应的激发。此外，为了建立哺乳动物和线虫先天免疫之间的相似性，我们研究了暴露于LPS的小鼠的表达谱，以鉴定pamsponsponsive基因，并分析了秀丽隐杆线虫同源物在防御反应中的作用。对3株秀丽隐杆线虫的lps应答基因进行了易感性检测，发现其中2株存在防御应答缺陷。其中一个突变体是daf-21(p673)，它在线虫的哺乳动物hsp90同源物中有一个错义突变。首先，我们建议继续进行涉及ced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。我们还将进一步表征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和功能和比较基因组学来鉴定和表征线虫和哺乳动物先天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.