Signaling mechanisms in plant innate immunity

描述（由申请人提供）：先天免疫是植物、动物和人类中最古老和进化上最保守的中央防御系统，其将宿主自体与非自体微生物病原体区分开来。它提供了对传染病的第一道诱导性防御，并成为预防持续和无所不在的微生物入侵的基础。先天免疫的一个关键功能是通过模式识别受体检测微生物相关的分子模式（MAMP，如细菌鞭毛蛋白）并启动适当的防御反应。最近的研究发现，在植物、动物和人类中，富含亮氨酸的重复序列受体在识别不同的MAMPs和激活多个MAPK级联反应方面具有显着的趋同进化。尽管MAPK级联在植物、蠕虫、苍蝇、哺乳动物和人类中普遍和重要地参与介导MAMP信号传导，但由于不同信号传导途径中的功能冗余、突变致死性和共享组分的复杂性，交织的信号网络的分子机制仍然是难以捉摸的。本研究的目的是以拟南芥为模型系统，建立MAMP信号转导的调控框架。本实验旨在整合分子、生物化学、细胞、遗传学和基因组学方法，研究多功能BAK 1-MAPKKK复合物和MAPKK-MAPK级联反应，并分析下游WRKY转录因子在植物防御反应中调控不同靶基因的作用。具体而言，该项目将集中于使用基于细胞的测定、转基因植物和在鞭毛蛋白受体FLS 2、受体信号传导伴侣BAK 1、MAPKKK-MAPKK-MAPK级联和WRKY转录因子中具有特定缺陷的功能丧失突变体来表征和整合15个拟南芥基因在鞭毛蛋白信号传导中的功能。蛋白质相互作用，磷酸化和泛素化分析，定量RT-PCR，全基因组芯片和染色质免疫沉淀将被用来阐明植物先天免疫的关键和保守的信号转导机制。三个具体目标是：目标1。分析BAK 1-MAPKKK信号复合物的相互作用和调节。剖析MAPKK-MAPK级联在会聚MAMP信号传导中的功能。阐明WRKY转录因子的功能和调控。公共卫生相关性：强大的先天免疫系统是预防持续和无所不在的微生物入侵的基础，并为植物，动物和人类提供了针对传染病的第一道诱导性防御。先天免疫的一个关键功能是检测微生物相关分子模式（MAMP）和启动适当的防御反应。最近的研究发现，富含亮氨酸的重复模式识别受体和多个MAPK级联的激活在MAMP感知中具有显着的趋同进化。从受体激酶信号复合物到交织的MAPK级联和WRKY转录控制的拟议研究将发现先天免疫信号传导中的新的和基本的分子机制，并为未来改善农业，环境和可再生能源生产以及治疗感染，炎症和自身免疫性疾病的人类健康提供创新工具。

DESCRIPTION (provided by applicant): Innate Immunity is the most ancient and evolutionarily conserved central defense system that distinguishes host-self from non-self microbial pathogens in plants, animals and humans. It provides the first line of inducible defense against infectious diseases and underlies the prevention of constant and omnipresent microbial invasion. A key function of innate immunity is the detection of microbe-associated molecular patterns (MAMPs, such bacterial flagellin) by pattern recognition receptors and the launch of appropriate defense responses. Recent discoveries have revealed remarkable convergent evolution in the recognition of diverse MAMPs by leucine-rich-repeat receptors and the activation of multiple MAPK cascades in plants, animals and humans. Despite the universal and essential involvement of MAPK cascades in mediating MAMP signaling in plants, worms, flies, mammals and humans, the molecular mechanisms underlying the intertwined signaling webs remain mostly elusive due to the complexity of functional redundancy, mutant lethality and shared components in distinct signaling pathways. The goal of this research project is to establish a regulatory framework for the convergent MAMP signaling using Arabidopsis thaliana as a model system. The proposed experiments aim to integrate molecular, biochemical, cellular, genetic, and genomic approaches to dissect the multifunctional BAK1-MAPKKK complexes and MAPKK-MAPK cascades, and to analyze the downstream WRKY transcription factors in controlling diverse target genes in plant defense responses. Specifically, the project will focus on characterizing and integrating the functions of 15 Arabidopsis genes in flagellin signaling using cell- based assays, transgenic plants and loss-of-function mutants with specific defects in the flagellin receptor FLS2, receptor signaling partner BAK1, MAPKKK-MAPKK-MAPK cascades and WRKY transcription factors. Protein interaction, phosphorylation and ubiquitination assays, quantitative RT- PCR, whole-genome microarray and chromatin-immunoprecipitation will be carried out to elucidate the key and conserved signaling mechanisms in plant innate immunity. Three Specific Aims are: Aim 1. Analyze interactions and regulations of BAK1-MAPKKK signaling complexes Aim 2. Dissect the MAPKK-MAPK cascade functions in convergent MAMP signaling Aim 3. Define functions and regulations of WRKY transcription factors. PUBLIC HEALTH RELEVANCE: The powerful innate immune system underlies the prevention of constant and omnipresent microbial invasion, and provides the first line of inducible defense against infectious diseases in plants, animals and humans. A key function of innate immunity is the detection of microbe- associated molecular patterns (MAMPs) and the launch of appropriate defense responses. Recent discoveries have revealed remarkable convergent evolution in MAMP perception by leucine-rich- repeat pattern recognition receptors and the activation of multiple MAPK cascades. The proposed research from receptor kinase signaling complexes to intertwined MAPK cascades and WRKY transcriptional controls will discover novel and fundamental molecular mechanisms in innate immune signaling, and provide innovative tools for future improvement of agriculture, environment and renewable energy production, as well as human health in treating infectious, inflammatory and autoimmune diseases.