DNA sensors and associated signaling pathways in the innate immune response

描述(申请人提供)：RNA和DNA可引起炎症反应，这对抗微生物免疫至关重要。DNA是炎性细胞因子和类型的有力触发者 I-干扰素基因转录以及caspase-1介导的促炎细胞因子IL-1？和IL-18。越来越多的证据表明，DNA识别不仅是抗微生物宿主防御的核心，也是DNA疫苗佐剂活性以及与系统性红斑狼疮等自身免疫性疾病相关的病理的主要因素。因此，我们理解DNA识别的分子基础是至关重要的。我们小组最近的工作表明，PYHIN家族成员在黑色素瘤-2中缺失(AIM2)和干扰素诱导蛋白(IFI16)作为微生物DNA的传感器。这两种蛋白质都通过HIN结构域与DNA结合。AIM2通过派林结构域与ASC结合，形成caspase-1激活的炎症体，而IFI16激活胞浆信号通路，涉及干扰素基因刺激物(STING)、坦克结合蛋白-1(TBK-1)和干扰素调节因子3(IRF3)，以调节I型干扰素基因的转录。敲除IFI16或其小鼠同源基因p204可阻止病毒DNA触发IRF3激活和干扰素？基因诱导，同时不影响对胞质RNA的反应。最近的证据也表明，IFI16可以在对Kaposi肉瘤疱疹病毒感染的核感应反应中形成炎症体。我们实验室的进一步工作也表明，DEAD盒解旋酶DEAD盒蛋白3X(DDX3X)在TBK1/IRF3信号通路中对RNA和细胞质DNA途径(包括IFI16)都是重要的，但其在先天性免疫中的作用仍未完全确定。在这项提议中要检验的基本假设是，IFI16扮演着一个 研究表明，DDX3X通过调节炎症反应在先天免疫和宿主防御微生物病原体中发挥核心作用，并且DDX3X是IFI16信号通路下游的重要组成部分。我们建议探索IFI16激活的分子机制，并确定IFI16和DDX3X在抗病毒宿主防御中的作用。这个项目将增加我们对先天免疫系统如何感知病原体的理解，从而导致新的治疗靶点。

DESCRIPTION (provided by applicant): RNA and DNA elicit inflammatory responses which are critical for anti-microbial immunity. DNA is a potent trigger of inflammatory cytokine and type I IFN gene transcription, as well as caspase-1-mediated processing of the pro-inflammatory cytokines IL-1? and IL-18. Growing evidence indicates that DNA recognition is central not only to anti-microbial host defenses but is also a major contributor to the adjuvant activity of DNA vaccines as well as the pathology associated with autoimmune diseases such as Systemic Lupus Erythematosis. It is therefore critical that we understand the molecular basis of DNA recognition. Recent work from our group has implicated the PYHIN family members Absent in melanoma-2 (AIM2) and the interferon-inducible protein (IFI16) as sensors of microbial DNA. Both proteins bind DNA via HIN domains. AIM2 engages ASC via a pyrin domain to form a caspase-1 activating inflammasome while IFI16 activates a cytosolic signaling pathway involving Stimulator of IFN genes (STING), TANK binding kinase-1 (TBK-1) and interferon regulatory factor 3 (IRF3) to regulate transcription of type I IFN genes. Knockdown of IFI16, or its murine ortholog p204 prevents viral DNA from triggering IRF3 activation and IFN? gene induction, while not affecting responses to cytosolic RNA. Recent evidence also indicates that IFI16 can form an inflammasome in responses to nuclear sensing of Kaposi's Sarcoma Herpes Virus infection. Additional work from our laboratories has also implicated the DEAD box helicase DEAD box protein 3x (DDX3x) in the TBK1/IRF3 signaling pathway important for both RNA and cytoplasmic DNA pathways (including for IFI16), but its role in innate immunity remains to be fully characterized. The underlying hypothesis to be tested in this proposal is that IFI16 plays a central role in innate immunity and host-defense to microbial pathogens by regulating inflammatory responses and that DDX3x is an important downstream component of the IFI16 signaling pathway. We propose to explore the molecular mechanisms of IFI16 activation and define the role of IFI16 and DDX3x in anti-viral host-defenses. This project will increase our understanding of how the innate immune system senses pathogens, leading to novel therapeutic targets.