Investigating the Antiviral Role of STING During Enteric RNA Virus Infection in Drosophila

项目摘要： 肠道作为物理和免疫屏障，以防止肠道感染。 病原体Cherry实验室使用果蝇作为人类和蚊子肠道的体内模型， 感染，以了解肠道先天免疫反应，以及它是如何影响的， 微生物群的组成。辛德比斯病毒是一种蚊媒病毒， 吸血时蚊子通过口腔传播。我们的初步数据表明果蝇 干扰素基因刺激因子（STING）的同源物在体内抗辛德毕斯病毒， 肠子哺乳动物STING通过结合内源性产生的环状二核苷酸来激活 通过环GMP-AMP合酶（cGAS）或通过细菌外源地。哺乳动物cGAS产生 在结合来自细菌或DNA病毒的胞质DNA后但未被活化的环状二核苷酸 通过结合RNA。我们的初步数据显示，最接近的cGAS直系同源物是抗病毒的， 肠道辛德毕斯感染对这种果蝇cGAS候选物的序列分析显示，它缺乏 在哺乳动物cGAS中发现的DNA结合结构域，表明d-cGAS感测非DNA 配体，可能是病毒RNA。宏基因组数据显示， 编码CDN酶，表明微生物群可以提供外源CDN池， 从随后的病毒感染引发基础STING活性。实际上，我们的初步数据显示 向缺乏其微生物群的果蝇外源性喂食CDN可保护其免受肠道辛德毕斯病毒的侵害 感染此外，我们发现STING可能通过激活自噬来抗病毒 和炎症性NF-κ B活化。 我们假设d-cGAS和微生物组都产生激活dSTING的CDN， 通过肠道内的感染依赖性自噬保护免受RNA病毒感染。到 在目标1中扩展这一假设，我们提出确定d-cGAS和CDN在以下方面的作用： STING依赖的抗病毒防御。此外，在目标2中，我们建议定义机制 STING在肠上皮细胞中具有抗病毒作用。这项工作揭示了古代cGAS的进化- STING防御途径，并定义了其他微生物群衍生的产品，如CDN， 可能影响肠道免疫力。

Project Summary: The intestine serves as a physical and immune barrier to protect against infection by enteric pathogens. The Cherry lab uses Drosophila as an in vivo model of human and mosquito enteric infection to understand the intestinal innate immune response and how it is influenced by the composition of the microbiota. Sindbis virus is a mosquito-borne virus that is transmitted to mosquito vectors orally during a blood meal. Our preliminary data suggest the Drosophila homologue of Stimulator of Interferon Genes (STING) is antiviral against Sindbis virus within the intestine. Mammalian STING is activated by binding cyclic dinucleotides produced endogenously by cyclic GMP-AMP synthase (cGAS) or exogenously by bacteria. Mammalian cGAS produces a cyclic dinucleotide after binding cytosolic DNA from bacteria or DNA viruses but is not activated by binding RNA. Our preliminary data shows that the closest cGAS ortholog is antiviral against enteric Sindbis infection. Sequence analysis of this Drosophila cGAS candidate reveals it lacks the DNA binding domain found in mammalian cGAS, suggesting that d-cGAS senses a non-DNA ligand, perhaps viral RNA. Metagenomic data reveals that Drosophila commensal bacteria encode CDN synthases indicating that the microbiota could provide an exogenous CDN pool to prime basal STING activity from subsequent viral infection. Indeed, our preliminary data suggests exogenous feeding of CDNs to flies lacking their microbiota protects against enteric Sindbis virus infection. Moreover, we found that STING may be antiviral through the activation of autophagy and inflammatory NF-kB activation. We hypothesize that both d-cGAS and the microbiome produce CDNs that activate dSTING to protect from RNA virus infection through infection-dependent autophagy within the intestine. To expand on this hypothesis in Aim 1 we propose to determine the role of d-cGAS and CDNs in STING-dependent antiviral defense. Additionally, in Aim 2 we propose to define the mechanism by which STING is antiviral in enterocytes. This work sheds light on evolution of the ancient cGAS- STING defense pathway and defines how additional microbiota-derived products, such as CDNs, may influence intestinal immunity.