Initiation and Regulation of Antiviral Innate Immunity

项目摘要 该提案的目标是确定模式识别受体环GMP-AMP合酶（cGAS） 作为高保真DNA传感器，驱动干扰素（IFN）和炎症反应。在人类和 在小鼠中，cGAS在结合DNA后合成第二信使环GMP-AMP（cGAMP）。该第二 信使在结合下游调节蛋白STING后刺激免疫应答。因此，在本发明中， cGAMP被认为是下一代佐剂。因为cGAS检测到的糖磷酸骨架 双链DNA，一个主要的问题是如何调节这种酶，以确保炎症 应答选择性地响应于病毒（而非自身）DNA而产生。自然界中的所有cGAS蛋白都含有 C-末端催化结构域，其对于DNA结合和cGAMP产生是必需且足够的。所有cGAS 蛋白质还含有功能不明确的N-末端结构域。在上一个融资周期，我们 发现cGAS N-末端结构域的功能是防止人类细胞内的自身DNA反应性。尽管 尽管对cGAS调节的这种了解，但关于其在感染性和非感染性中的活性仍不清楚。 contexts.事实上，我们已经发现了惊人的物种特异性调节机制的多样性， cGAS活动。了解驱动cGAS介导的炎症反应的调节事件将使 讨论如何激发保护性免疫力以对抗感染和癌症。在本申请中，我们 提出利用天然cGAS多样性来解释DNA诱导的IFN应答的机制（目的1）， 并利用合成生物学将cGAS进一步多样化为“保卫蛋白”，这提供了一种新的手段， 探测宿主-病毒相互作用（目的2）。

Project Summary The goal of this proposal is to identify how the pattern recognition receptor cyclic GMP-AMP synthase (cGAS) operates as a high-fidelity DNA sensor that drives interferon (IFN) and inflammatory responses. In humans and mice, cGAS synthesizes the second messenger cyclic GMP-AMP (cGAMP) upon binding DNA. This second messenger stimulates immune responses upon binding the downstream regulatory protein STING. As such, cGAMP is considered a next-generation adjuvant. Because cGAS detects the sugar-phosphate backbone of double stranded DNA, a major question relates to how this enzyme is regulated to ensure inflammatory responses are selectively generated in response to viral (but not self) DNA. All cGAS proteins in nature contain a C-terminal catalytic domain that is necessary and sufficient for DNA binding and cGAMP production. All cGAS proteins also contain an N-terminal domain of poorly defined function. In the previous funding period, we discovered that the cGAS N-terminal domain functions to prevent self-DNA reactivity within human cells. Despite this insight into cGAS regulation, much remains unclear about its activities in infectious and non-infectious contexts. Indeed, we have discovered striking species-specific diversity of regulatory mechanisms that control cGAS activities. Understanding regulatory events that drive cGAS-mediated inflammatory responses will enable discussions of how protective immunity can be stimulated against infection and cancer. In this application, we propose to leverage natural cGAS diversity to explain the mechanisms of DNA-induced IFN responses (Aim 1), and leverage synthetic biology to further diversify cGAS into a “guard protein”, which provides a novel means of probing host-virus interaction (Aim 2).