Regulation of cGAS-Mediated Cytosolic DNA Sensing Pathway

项目摘要 病毒DNA和泄漏的线粒体DNA（mtDNA）可以触发细胞溶质DNA传感器，环GMP-AMP 干扰素合成酶（cGAS）启动干扰素（IFN）产生信号级联。DNA的异常激活 传感通路可导致炎症和自身免疫性疾病，如系统性红斑狼疮。 然而，宿主如何限制对病毒DNA和线粒体DNA的过度或有害的免疫反应并不清楚 阐明。因此，迫切需要确定防止cGAS异常激活的保护机制。 介导的先天免疫。 我们在本申请中的总体目标是阐明宿主调节反馈机制， cGAS过度激活初步实验鉴定了补体C1 q结合蛋白（C1 QBP）， 主要在线粒体中表达的与cGAS相关的蛋白质。我们的试点研究发现， 敲除C1 QBP增强DNA诱导的IFN应答，表明C1 QBP负调节cGAS 发信号。我们的初步研究进一步发现，病毒感染诱导的线粒体应激导致 C1 QBP从线粒体释放到细胞质。根据现有文献和我们的初步研究， 数据，我们提出了以下中心假设：线粒体应激导致C1 QBP从 线粒体进入胞质溶胶。胞质C1 QBP和cGAS之间的直接相互作用抑制I型IFN 表达，从而提供防止先天性免疫应答的异常或持续激活的机制。 应答 目的1明确C1 QBP在细胞质DNA介导的先天性免疫中的作用。 目的2将确定C1 QBP限制胞质DNA诱导的cGAS的保护机制 activation. CGAS活性必须严格调节，因为持续的IFN产生可导致自身免疫性疾病。 这种探索性的R21应用提出C1 QBP作为线粒体基质中的隐藏宿主保护剂。当 当线粒体被感染和其他细胞应激损伤时，C1 QBP从线粒体释放， 抑制cGAS活性，从而防止由泄漏的mtDNA触发的过度IFN应答。本研究 将阐明一个优雅的宿主自我调节机制，为开发新的 感染性和自身免疫性疾病的治疗策略。

Project summary Viral DNA and leaked mitochondrial DNA (mtDNA) can trigger the cytosolic DNA sensor, cyclic GMP-AMP synthase (cGAS) to initiate the interferon (IFN) production signal cascade. Aberrant activation of the DNA sensing pathway can result in inflammatory and autoimmune diseases, such as systemic lupus erythematosus. However, how host limits excessive or detrimental immune responses to viral DNA and mtDNA is not well elucidated. Thus, it is pressing to define the protective mechanisms that prevent aberrant activation of cGAS- mediated innate immunity. Our overall objective in this application is to elucidate a host regulatory feedback mechanism that prevents cGAS from over-activating. Pilot experiments identified the complement C1q binding protein (C1QBP), a protein predominantly expressed in mitochondria as being associated with cGAS. Our pilot studies found that knockout of C1QBP augmented DNA-induced IFN response, suggesting C1QBP negatively regulates cGAS signaling. Our preliminary studies further discovered that viral infection-induced mitochondrial stress resulted in the release of C1QBP from mitochondria to the cytoplasm. Based on the existing literature and our preliminary data, we propose the following central hypothesis: Mitochondrial stress causes the release of C1QBP from mitochondria into cytosol. Direct interaction between cytosolic C1QBP and cGAS inhibits type I IFN expression, thereby providing a mechanism that prevents aberrant or sustained activation of innate immune responses. Aim 1 will define the role of C1QBP in cytosolic DNA-mediated innate immunity in vitro and in vivo. Aim 2 will determine the protective mechanisms by which C1QBP limits cytosolic DNA-induced cGAS activation. cGAS activity must be tightly regulated because sustained IFN production can lead to autoimmune diseases. This exploratory R21 application proposes C1QBP as a hidden host protector in mitochondria matrix. When mitochondria are damaged by infection and other cellular stresses, C1QBP is released from mitochondria to inhibit cGAS activity, thereby preventing excessive IFN response triggered by the leaked mtDNA. This study will elucidate an elegant host self-regulation mechanism, providing foundations for developing novel therapeutic strategies for infectious and autoimmune diseases.