Crosstalk between FceRI and MAVS signaling pathways in mast cells

项目摘要 在过去的几十年里，哮喘和过敏性疾病的患病率一直在增加。IGE扮演着一个 在哮喘和过敏性疾病的发病机制中起中心作用。IL-4和IL-13刺激血管生成 伊格。多价变应原诱导肥大细胞上IgE结合的高亲和力IgE受体(FceRI)的交联 细胞和嗜碱性粒细胞。FceRI的交联启动几种蛋白酪氨酸激酶(PTKs)的激活 包括受体相关的Lyn和其他Src PTK，它们可以磷酸化 免疫受体酪氨酸激活基序(ITAM)在受体的信号亚基中。 磷酸化G亚基招募Syk，这是触发下游激活事件所必需的PTK(即， 预先形成的致敏介质的脱颗粒和二十烷类化合物的从头合成和分泌 各种细胞因子和趋化因子)，最终导致过敏反应的启动。 呼吸道病毒感染引起的哮喘急性加重表现为严重的发病率、死亡率、 以及沉重的医疗成本。感染甲型流感病毒(IAV)的宿主细胞通过 模式识别受体，如RIG-I。RIG-I样受体(RLRs)的信号通过 适配器线粒体抗病毒信号蛋白(MAVS)位于线粒体外膜。一次 激活后，MAVS进而激活TBK1和IKKE，导致转录的磷酸化和激活 因子IRF3/IRF7和核因子-kB。IRF3和IRF7激活了I型干扰素基因的转录，而 核因子-kB激活炎性细胞因子基因。肥大细胞也与病毒感染有关。桅杆 依赖RIG-I/MAVS的IAV感染期间细胞因子和趋化因子的产生 而组胺的产生是通过不依赖RIG-I/MAVS的机制进行的。肥大细胞- 基因缺陷小鼠和酮替芬(肥大细胞稳定剂)处理的小鼠表现出IAV诱导的肺病理减轻 分别与肥大细胞充足的小鼠和未处理的小鼠进行比较。因此，肥大细胞很可能 通过FceRI和抗病毒信号通路之间的串扰导致哮喘加重。 我们的初步数据表明，在RLR抗病毒途径的信号分子中，MAV， 在抗原/IgE诱导的肥大细胞活化中，独特而强烈地抑制Syk活性。因此，Syk可能是 受Syk和/或MAVS相关的酪氨酸磷酸酶的负调控(S)。在目标1中，我们将调查 Syk是否受Tula-2或SHP-1/2以MAV依赖的方式调节。这些候选人 对于这种可能性，将对磷酸酶进行深入的分析。在目标2中，我们将研究体内和体内 肥大细胞表达的MAVs和Syk在IAV感染中的体外作用。因此，通过这个项目，我们将获得 对肥大细胞中的MAV如何调节Syk以及FceRI之间的串扰如何进行机械洞察 抗病毒RLR信号通路影响IAV感染。这些信息将成为小说的基础 IAV引起的哮喘加重的治疗/预防干预。

Project Summary The prevalence of asthma and allergic diseases has been increasing for the last several decades. IgE plays a central role for the pathogenesis of asthma and allergic diseases. IL-4 and IL-13 stimulate the production of IgE. Multivalent allergen induces the cross-linking of IgE-bound high-affinity IgE receptors (FceRI) on mast cells and basophils. Cross-linking of FceRI initiates activation of several protein-tyrosine kinases (PTKs) including receptor-associated Lyn and other Src PTKs, which phosphorylate tyrosine residues of the immunoreceptor tyrosine-based activation motifs (ITAMs) in signaling subunits of the receptor." Tyrosine- phosphorylated g subunits recruit Syk, the PTK essential for triggering downstream activation events (i.e., degranulation of preformed allergenic mediators and de novo synthesis and secretion of eicosanoids and various cytokines and chemokines), eventually leading to the initiation of allergic reactions. Respiratory virus infection-induced acute exacerbations of asthma represent severe morbidity, mortality, and burdensome healthcare costs. Host cells infected with influenza A virus (IAV) sense the infection by pattern recognition receptors such as RIG-I. Signaling by RIG-I-like receptors (RLRs) occurs through the adaptor mitochondrial antiviral-signaling protein (MAVS) at the outer membrane of the mitochondria. Once activated, MAVS in turn activates TBK1 and IKKe, leading to phosphorylation and activation of the transcription factors IRF3/IRF7 and NF-kB. IRF3 and IRF7 activate the transcription of type I interferon (IFN) genes while NF-kB activates that of inflammatory cytokine genes. Mast cells are also implicated in virus infections. Mast cell production of cytokines and chemokines during IAV infection occurs in a RIG-I/MAVS-dependent mechanism, whereas histamine production occurs through a RIG-I/MAVS-independent mechanism. Mast cell- deficient mice and ketotifen (mast cell stabilizer)-treated mice showed reduced IAV-induced lung pathology compared to mast cell-sufficient mice and untreated mice, respectively. Therefore, it is likely that mast cells contribute to asthma exacerbations via the crosstalk between FceRI and antiviral signaling pathways. Our preliminary data demonstrates that MAVS, among the signaling molecules of RLR antiviral pathways, uniquely and strongly inhibits Syk activity in antigen/IgE-induced mast cell activation. Thus, Syk may be negatively regulated by a Syk- and/or MAVS-associated tyrosine phosphatase(s). In Aim 1, we will investigate whether Syk is regulated by TULA-2 or SHP-1/2 in a MAVS-dependent manner. These candidate phosphatases will be intensively analyzed for this possibility. In Aim 2, we will investigate the in vivo and in vitro roles of mast cell-expressed MAVS and Syk in IAV infection. Therefore, through this project, we will gain mechanistic insights into how Syk is regulated by MAVS in mast cells and how the crosstalk between FceRI and antiviral RLR signaling pathways impacts IAV infection. Such information will be basis for novel therapeutic/preventive interventions of IAV-induced asthma exacerbations.