Role of OCIAD1 in RIG-I-mediated STAT1 signaling pathway

项目摘要 宿主模式识别受体，如视黄酸诱导的基因I（RIG-I），感测病毒RNA，并诱导病毒RNA的表达。 干扰素介导的先天免疫以限制病毒感染。已经确定RIG-I诱导I型 通过线粒体抗病毒信号蛋白（MAVS）和TANK结合激酶1表达干扰素（IFN） （TBK1）。I型IFN作为危险信号，并进一步激活JAK-STAT信号通路，以诱导 干扰素刺激基因（ISG），从而限制病毒感染。最近的一项研究报告了另一个RIG-I 信号传导分支，其中MAVS直接诱导STAT 1磷酸化和ISG表达，通过 酪氨酸激酶SYK RIG-I-STAT 1信号转导已被证明在早期宿主防御中至关重要。 病毒感染阶段。然而，连接MAVS和SYK的关键中间信号分子缺失 因为MAVS不具有基于免疫受体酪氨酸的激活基序 （ITAM）负责SYK结合和激活。因此，在RIG-I-STAT 1中存在知识空白 信号通路本申请的目的是确定卵巢癌的作用 RIG-I-STAT 1信号通路中含有免疫反应性抗原结构域1（OCIAD 1）的蛋白质与宿主 防御病毒感染。尽管RIG-I-STAT 1信号通路是最近建立的，但存在一个与RIG-I-STAT 1信号通路相关的信号通路。 MAVS和SYK之间缺少联系生物信息学分析表明，OCIAD 1具有ITAM样基序， 可以招募并激活SYK我们的初步数据和以前的研究表明，OCIAD 1与 MAVS此外，OCIAD 1的缺陷损害RIG-I介导的STAT 1磷酸化。另外我们 等人报道甲型流感病毒的NS 2蛋白与OCIAD 1相互作用。NS 2过表达 阻断STAT 1磷酸化。因此，根据现有文献和我们的初步数据，我们 假设OCIAD 1将SYK募集到MAVS信号体，并激活STAT 1磷酸化， RIG-I-STAT 1信号通路。此外，流感NS 2抑制RIG-I-STAT 1信号通路 通过对抗OCIAD 1目的1研究OCIAD 1在IAV感染中的作用 主要细胞目的2：探讨OCIAD 1调控RIG-I-STAT 1的分子机制 以及NS 2如何拮抗这一通路。 我们的研究将填补RIG-I-STAT 1信号级联的空白，并确定NS 2在以下方面的潜在作用： 宿主先天免疫应答的破坏，这将为病毒逃避宿主的新策略提供见解 国防监视我们的研究结果不仅有助于开发有效的抗病毒疗法， 也加深了我们对宿主对病毒的先天免疫反应的理解。

Project summary Host pattern recognition receptors, such as retinoic acid-induced gene I (RIG-I), sense viral RNA and elicit interferon-mediated innate immunity to restrict viral infection. It is well-established that RIG-I induces type I interferon (IFN) expression via the mitochondrial antiviral signaling protein (MAVS) and TANK-binding kinase 1 (TBK1). Type I IFN acts a danger signal and further activates the JAK-STAT signaling pathway to induce interferon-stimulated genes (ISGs), thereby limiting viral infection. A recent study reported another RIG-I signaling branch, in which MAVS directly induces STAT1 phosphorylation and ISG expression through the tyrosine kinase SYK. The RIG-I-STAT1 signaling has been shown to be critical for host defense at the early stage of viral infection. However, the critical intermediate signal molecule(s) linking MAVS and SYK is missing in this signal cascade because MAVS does not have the immunoreceptor tyrosine-based activation motif (ITAM) responsible for SYK binding and activation. Thus, there is a knowledge gap in the RIG-I-STAT1 signaling pathway. The objective in this application is to determine the role of the ovarian cancer immunoreactive antigen domain containing 1 (OCIAD1) in the RIG-I-STAT1 signaling pathway and host defense to viral infection. Although the RIG-I-STAT1 signaling pathway is established recently, there is a missing link between MAVS and SYK. Bioinformatic analysis showed that OCIAD1 had an ITAM-like motif that can recruit and activate SYK. Our preliminary data and previous studies showed that OCIAD1 interacted with MAVS. Furthermore, deficiency of OCIAD1 impaired RIG-I-mediated STAT1 phosphorylation. In addition, we and others reported that the NS2 protein of influenza A virus interacted with OCIAD1. Overexpression of NS2 blocked STAT1 phosphorylation. Thus, based on the existing literature and our preliminary data, we hypothesize that OCIAD1 recruits SYK to the MAVS signalosome and activates STAT1 phosphorylation in the RIG-I-STAT1 signaling pathway. Furthermore, influenza NS2 suppresses the RIG-I-STAT1 signaling pathway by antagonizing OCIAD1. Aim 1 will determine the role of OCIAD1 in IAV infection in vivo and in human primary cells. Aim 2 will dissect the molecular mechanisms of how OCIAD1 regulates the RIG-I-STAT1 signaling and how NS2 antagonizes this pathway. Our study will bridge the gaps in the RIG-I-STAT1 signaling cascades and determine a potential role of NS2 in subversion of host innate immune response, which will provide insights on a new viral strategy for evading host defense surveillance. The findings in our study will not only help develop effective antiviral therapeutics but will also deepen our understanding of host innate immune responses to viruses.