Modification and dynamic regulation of Argonaute proteins-the key small RNA pathway components in host innate immunity

 描述（由申请人提供）：真核生物，包括动物和植物，已经进化出复杂的免疫系统来保护自己免受病原体的侵害。小RNA（sRNA）是短的非编码调节RNA，其通过与Argonaute（AGO）蛋白结合并指导具有互补序列的基因沉默来诱导RNA干扰（RNAi）。我们的工作和其他人的工作已经证明，来自宿主或病原体的sRNA通过AGO蛋白发挥功能，并在宿主-病原体相互作用中发挥重要作用。然而，基本的监管机制仍然难以捉摸。我们的长期目标是了解sRNA和RNAi在宿主先天免疫中的动态调节。AGO蛋白是sRNA介导的基因沉默的关键参与者，并且我们假设它们被其相关蛋白修饰和调节以调节sRNA介导的基因沉默。本文以拟南芥及其病原菌Pseudomonasaesthingae和侵袭性病原真菌Botrytis cinerea为模型，研究AGO在RNAi途径中的修饰和调控，以及在宿主抗细菌和抗真菌免疫应答中的作用。在过去的资助期间，我们已经确定了不同类别的宿主sRNAs调节宿主免疫力，并已证明，拟南芥AGO 2（AtAGO 2）是高度诱导的细菌感染和积极调节宿主免疫力。我们还证明了B.灰霉病菌将其sRNA递送到宿主细胞中并劫持宿主AtAGO 1以抑制宿主免疫基因以成功感染。为了获得AtAGO 1和AtAGO 2如何调节的机制理解，我们通过蛋白质组学分析鉴定了它们的相关蛋白。此次更新将研究AtAGO 1和AtAGO 2在RNA干扰途径和宿主先天免疫中通过其相关蛋白的修饰和调节。本研究的结果将大大推进我们对RNAi在宿主免疫反应中对病原体的动态控制的理解，这将对农业和人类健康产生重大影响。具体目标是：1.阐明蛋白质精氨酸甲基转移酶在宿主免疫中修饰和调节AtAGO功能的作用。2.研究DDX 3样RNA解旋酶在宿主免疫中调节AtAGO功能的功能。3.研究蛋白磷酸酶在调节AtAGO和宿主免疫中的作用。

 DESCRIPTION (provided by applicant): Eukaryotic organisms, including animals and plants, have evolved sophisticated immune systems to protect themselves against pathogens. Small RNAs (sRNAs) are short, non-coding regulatory RNAs that induce RNA interference (RNAi) by binding to Argonaute (AGO) proteins and directing silencing of genes with complementary sequences. Our work and those of others have demonstrated that sRNAs, derived from either hosts or pathogens, function through AGO proteins and play an important role in host-pathogen interactions. However, the underlying regulatory mechanisms remain elusive. Our long-term goal is to understand the dynamic regulation of sRNAs and RNAi in host innate immunity. AGO proteins are key players of sRNA- mediated gene silencing, and we hypothesize that they are modified and regulated by their associated proteins to modulate sRNA-mediated gene silencing. Here, we seek to understand the modification and regulation of AGOs in RNAi pathway, and in host antibacterial and antifungal immune responses, by using model plant-pathogen interaction systems - Arabidopsis thaliana and its bacterial pathogen Pseudomonas syringae and aggressive fungal pathogen Botrytis cinerea. During the last funding period, we have identified diverse classes of host sRNAs regulating host immunity, and have demonstrated that Arabidopsis AGO2 (AtAGO2) is highly induced by bacterial infection and positively regulates host immunity. We have also shown that B. cinerea delivers its sRNAs into host cells and hijacks host AtAGO1 to suppress host immunity genes for successful infection. To obtain a mechanistic understanding of how AtAGO1 and AtAGO2 are regulated, we have identified their associated proteins via proteomics analysis. This renewal will study the modification and regulation of AtAGO1 and AtAGO2 by their associated proteins in RNAi pathways and host innate immunity. The output of this study will significantly advance our understanding of dynamic control of RNAi in host immune responses against pathogens, which will have great impact on both agricultural and human health. The specific aims are: 1. Elucidate the role of protein arginine methyltransferases in modification and regulation of AtAGO function in host immunity. 2. Investigate the function of DDX3-like RNA helicases in modulating AtAGO function in host immunity. 3. Study the role of protein phosphatases in modulating AtAGO and host immunity.