Pathogen sensing by nuclear hormone receptors in C. elegans intestinal epithelial cells

项目总结/摘要 肠上皮细胞中的病原体感知和免疫效应诱导机制并不清楚。 完全理解病原体感应和免疫稳态机制的破坏 肠上皮细胞可导致生态失调和炎症，以及对细菌感染的易感性。 利用免疫学方法，已经对肠上皮细胞免疫和宿主-病原体相互作用进行了关键性的研究。 线虫C.优雅线虫通过保守的免疫系统对细菌感染进行先天性免疫防御 免疫途径，但病原体检测的机制是未知的，在这种生物体。在线虫中， 与其它后生动物相比，核激素受体（NHRs）家族已显著扩大。 NHRs是一种配体门控转录因子，能够感知内源性和外源性信号以诱导适应性细胞凋亡。 转录反应。梭线虫基因组编码274个NHR，其中260个是人类NHR的同源物， HNF 4 α。HNF 4 α是炎症性肠病中的关键NHR，但其作用机制尚不清楚。 HNF 4 α介导人类炎症性肠病尚不清楚。这一提议的核心假设是 梭线虫HNF 4 α同源物是一个古老的病原体传感器家族，其在进化过程中的扩展， C. elegans是由它们检测各种病原体的功能驱动的。以下主要调查结果支持这一观点 假设：（i）核激素受体NHR-86/HNF 4 α感知细胞环境并激活 C.线虫肠道免疫防御;（ii）NHR-86/HNF 4 α是病原体抗性和免疫防御所必需的。 对革兰氏阳性人体病原体E. faecalis;和（iii）不同的C.秀丽隐杆线虫HNF 4 α 同源物是针对革兰氏阴性病原体的病原体防御和免疫效应调节所必需的 P.铜绿。在本提案中，目标1将定义C的作用。线虫NHR-86/HNF 4 α在病原体检测中的应用 以及E.粪便感染使用转录组学，ChIP- 测序、组织特异性拯救和遗传上位性。目标2将描述一个单独的C的功能。 在铜绿假单胞菌感染期间，线虫HNF 4 α同源物在病原体感知中的作用。该方法包括： 转录组学、全局NHR结合位点鉴定、组织特异性拯救和铜绿假单胞菌遗传学。 总的来说，这些研究将描述一个全新的免疫激活范式， 解决了病原体在C.优雅这些调查结果还将建立国家人权机构 作为进化上古老的病原体传感器。最后，我们希望详细分析 HNF 4 α在哺乳动物病原体感知和炎症性肠道中的作用 疾病

PROJECT SUMMARY/ABSTRACT The mechanisms of pathogen sensing and immune effector induction in intestinal epithelial cells are not completely understood. Disruption in the mechanisms of pathogen sensing and immune homeostasis in intestinal epithelial cells can lead to dysbiosis and inflammation, as well as susceptibility to bacterial infection. Key insights into intestinal epithelial cell immunity and host-pathogen interactions have been made using the nematode C. elegans. Nematodes mount innate immune defenses against bacterial infection via conserved immune pathways, but the mechanisms of pathogen detection are unknown in this organism. In nematodes, the family of nuclear hormone receptors (NHRs) has dramatically expanded compared to other metazoans. NHRs are ligand-gated transcription factors that sense endogenous and exogenous signals to induce adaptive transcriptional responses. The C. elegans genome encodes 274 NHRs, of which 260 are homologs of human HNF4α. HNF4α is a key NHR involved in inflammatory bowel disease, though the mechanism through which HNF4α mediates inflammatory bowel disease in humans is unknown. The central hypothesis of this proposal is that C. elegans HNF4α homologs are an ancient family of pathogen sensors whose evolutionary expansion in C. elegans was driven by their function in detecting diverse pathogens. The following key findings support this hypothesis: (i) The nuclear hormone receptor, NHR-86/HNF4α, senses the cellular environment and activates C. elegans intestinal immune defenses; (ii) NHR-86/HNF4α is required for pathogen resistance and immune response towards the gram positive human pathogen E. faecalis; and (iii) A different C. elegans HNF4α homolog is required for pathogen defense and immune effector regulation against the gram negative pathogen P. aeruginosa. In this proposal, Aim 1 will define the role of C. elegans NHR-86/HNF4α in pathogen detection and immune effector induction during E. faecalis infection using a combination of transcriptomics, ChIP- sequencing, tissue-specific rescue and genetic epistasis. Aim 2 will characterize the function of a separate C. elegans HNF4α homolog in pathogen sensing during P. aeruginosa infection. The approach includes: transcriptomics, global NHR binding site identification, tissue specific rescue, and P. aeruginosa genetics. Collectively, these studies will characterize a fundamentally new paradigm of immune activation, which will solve a major conundrum of how pathogens are sensed in C. elegans. These findings will also establish NHRs as evolutionarily ancient pathogen sensors. Ultimately, the expectation is that detailed dissection of this mechanism will shed light on the role of HNF4α in mammalian pathogen sensing and inflammatory bowel disease.