Molecular Genetics of Innate Immunity in C. elegans

描述（由申请人提供）：最近的研究表明，哺乳动物先天免疫的关键信号传导途径具有古老的进化起源，在无脊椎动物生物体（如昆虫和线虫）的免疫应答级联中很明显。本项目的长期目标是对C. elegans，预期在这种遗传上易处理的宿主生物体中的免疫的系统研究将阐明哺乳动物先天免疫中病原体识别和防御的进化保守机制。我们已经启动了一个多管齐下的功能基因组学方法来研究C。线虫免疫我们鉴定了保守的PMK-1 p38 MARK通路和TIR-1的需要，TIR-1是一种保守的Toll-白细胞介素-1-受体（TIR）结构域衔接蛋白，其似乎在PMK-1通路的上游起作用。我们已经使用全基因组微阵列分析来确定PMK-1途径调控下的候选免疫效应物。我们已经从基于RNAi的系统性筛选中确定了可能会聚集在PMK-1上的其他候选免疫信号传导组分。基于这些数据，我们提出了这一建议的具体假设，即病原体感染激活TIR-1-PMK-1信号级联，通过调节感染部位分泌的抗菌因子来赋予免疫力。我们提出了三个具体的目标来定义TIR-1-PMK-1途径赋予免疫力的机制。首先，我们将确定PMK-1 MAPK通路是否在感染部位的细胞中局部作用或在病原体防御中全身作用。其次，我们将通过对PMK-1转录靶点的功能分析来确定PMK-1赋予病原体抗性的调控机制。第三，我们将明确TIR-1激活PMK-1 MAPK通路的机制。我们将解剖TIR-1蛋白的功能结构域和相互作用的蛋白质的特点，分配候选基因从我们的RNAi筛选TIR-1-PMK-1途径的遗传相互作用分析，并系统地确定所需的额外的基因TIR-1激活PMK-1途径使用互补的遗传方法。总之，p38 MAPK通路构成了先天免疫的关键介质，其从蠕虫到人类都是保守的。我们预计，由p38 MAPK直系同源物PMK-1介导的免疫机制的遗传解剖将为哺乳动物先天免疫机制提供重要的见解，包括哺乳动物TIR-1直系同源物SARM的作用。

DESCRIPTION (provided by applicant): Recent studies have revealed that key signaling pathways of mammalian innate immunity have ancient evolutionary origins evident in the immune response cascades of invertebrate organisms such as insects and nematodes. The long-term goal of this project is to carry out the comprehensive analysis of innate immunity in C. elegans, with the anticipation that the systematic study of immunity in this genetically tractable host organism will illuminate evolutionarily conserved mechanisms of pathogen recognition and defense in mammalian innate immunity. We have initiated a multi-pronged functional genomic approach to the study of C. elegans immunity. We identified a requirement for a conserved PMK-1 p38 MARK pathway and TIR-1, a conserved Toll-lnterleukin-1-Receptor (TIR) domain adaptor protein that appears to function upstream of the PMK-1 pathway. We have used genome-wide microarray analysis to identify candidate immune effectors under the regulation of the PMK-1 pathway. We have identified additional candidate immune signaling components that may converge on PMK-1 from a systematic RNAi-based screen. Based on these data, we have developed the specific hypothesis of this proposal, which is that pathogen infection activates a TIR-1-PMK-1 signaling cascade that confers immunity through the regulation of secreted antimicrobial factors at the site of infection. We propose three specific aims to define the mechanisms by which the TIR-1-PMK-1 pathway confers immunity. First, we will determine whether the PMK-1 MAPK pathway acts locally in cells at the site of infection or systemically in pathogen defense. Second, we will define the mechanisms regulated by PMK-1 that confer pathogen resistance by functional analysis of PMK-1 transcriptional targets. Third, we will define the mechanism of TIR-1 activation of the PMK-1 MAPK pathway in response to pathogen. We will dissect the functional domains of the TIR-1 protein and characterize interacting proteins, assign candidate genes from our RNAi screen to the TIR-1-PMK-1 pathway by genetic interaction analysis, and systematically identify additional genes required for TIR-1 activation of the PMK-1 pathway using complementary genetic methods. In summary, the p38 MAPK pathway constitutes a critical mediator of innate immunity that has been conserved from worms to humans. We anticipate that the genetic dissection, of the mechanisms of immunity mediated by the p38 MAPK ortholog, PMK-1, will provide important insights into the mechanisms of mammalian innate immunity, including the role of the mammalian TIR-1 ortholog, SARM.