Molecular basis of viral DNA sensing through the cGAS-STING pathway

通过 cGAS-STING 途径检测病毒 DNA 的分子基础

• 批准号: 10549776
• 负责人: Pingwei Li
• 金额: $ 36.09万
• 依托单位: TEXAS A&M AGRILIFE RESEARCH
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-02-20 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10549776
• 关键词: Address; Autoimmune Diseases; Binding; C-terminal; CREBBP gene; Cell Nucleus; Cells; Complex; Cryoelectron Microscopy; Crystallization; Cyclic GMP; DNA; Dinucleoside Phosphates; Event; Family; Gene Expression; Genetic Transcription; Goals; Health; Human; Immune response; Immune system; Infection; Innate Immune Response; Innate Immune System; Interferon Type I; Interferon-beta; Interferons; Invaded; Investigation; Length; Ligand Binding; Ligand Binding Domain; Malignant Neoplasms; Mediating; Membrane; Molecular; Molecular Conformation; Mus; Natural Immunity; Nucleic Acids; Pathway interactions; Pattern recognition receptor; Peptides; Periodicity; Phosphorylation; Protein Kinase; RNA; Research; Role; Second Messenger Systems; Signal Induction; Signal Pathway; Signal Transduction; Stimulator of Interferon Genes; Structure; Surface Plasmon Resonance; TBK1 gene; Viral; Viral Physiology; Virus Diseases; X-Ray Crystallography; base; cytokine; dimer; ds-DNA; inhibitor; innate immune pathways; innovation; microbial; mimetics; pathogen; promoter; protein activation; recruit; sensor; transcription factor; viral DNA; viral detection

The Molecular Basis of Viral DNA Sensing through the cGAS-STING Pathway The innate immune response is the first line of defense against invading pathogens. Viral nucleic acids, such as DNA and RNA, serve as danger signals that induce potent immune responses in infected cells. The detection of viral nucleic acids is a central strategy by which the hosts sense infection and launch protective immune responses. Cyclic GMP-AMP synthase (cGAS) is a cytosolic dsDNA sensor in innate immunity. It is activated by viral DNA and catalyzes the synthesis of a noncanonical cyclic dinucleotide 2ʹ, 3ʹ cGAMP (referred to as cGAMP). As a second messenger, cGAMP stimulates the induction of type I interferons (IFNs) via the adaptor STING located on the ER membrane. The engagement of cGAMP by STING leads to the recruitment and activation of the protein kinase TBK1. The transcriptional factor IRF-3 is then recruited to the signaling complex by phosphorylated STING. The induced proximity of IRF-3 and TBK1 leads to IRF-3 phosphorylation and activation. Phosphorylated IRF-3 oligomerizes, translocates to the nucleus, and induces the expression of type I IFNs, conferring antiviral activity to the host and activating the acquired immune responses. To understand the molecular basis of viral DNA sensing through the cGAS-STING pathway, the PI determined the crystal structures of cGAS in isolation and in complex with dsDNA; the structures of STING in isolation and in complex with cGAMP; the structures of mouse TBK1 bound to two inhibitors; the structure of phosphorylated STING C-terminal peptide bound to IRF-3; and the structure of a phosphomimetic dimer of IRF-3. These comprehensive structural and functional studies significantly advanced our understanding about how the innate immune system responds to viral DNA at molecular level. However, it remains unknown how cGAMP binding activates STING and mediates the recruitment and activation of TBK1 and IRF-3 at the signaling complex. In addition, the exact mechanism of how phosphorylation induces the activation of IRF-3 and facilitates its association with the IFN-β promoter remains to be determined. Built-upon our strong preliminary studies, the proposed research will elucidate the molecular bases of several key steps of the cGAS-STING pathway with the following aims: 1). Determine the structural basis of TBK1 recruitment by STING; 2). Elucidate the molecular basis of STING activation by cGAMP; 3). Delineate the mechanism of IRF-3 activation by TBK1. The proposed studies represent a rigorous and comprehensive investigation into the mechanisms of cytosolic DNA sensing and will dramatically advance our understanding of the molecular basis of innate immunity against viral infection. In addition, they provide a structural framework for innovative approaches to treat viral diseases, autoimmune disorders, and cancer by manipulating the innate immune response.

CGAS-STING途径传感病毒DNA的分子基础 先天免疫反应是抵御入侵病原体的第一道防线。病毒核酸，如 作为DNA和RNA，它们是危险信号，可以在感染细胞中诱导强大的免疫反应。这个 病毒核酸的检测是宿主感知感染和启动保护性免疫的中心策略 免疫反应。环状GMP-AMP合成酶(CGAS)是天然免疫中的胞质dsDNA感受器。它是 被病毒DNA激活并催化合成非规范的环二核苷酸2ʹ，3ʹcGAMP(参考文献 至cGAMP)。作为第二信使，cGAMP刺激I型干扰素(IFN)通过 位于ER膜上的适配器套。斯汀与cGAMP的接触导致了招聘 和蛋白激酶TBK1的激活。转录因子IRF-3随后被招募到信号转导中 由磷酸化的刺痛复合而成。IRF-3和TBK1的诱导邻近导致IRF-3的磷酸化 和激活。磷酸化的IRF-3寡聚，移位到细胞核，并诱导表达 I型干扰素，赋予宿主抗病毒活性，激活获得性免疫反应。至 了解通过cGAS-STING途径感知病毒DNA的分子基础，等电点决定了 CGAS的分离和与dsDNA络合物的晶体结构；分离和In的刺状结构 与cGAMP的络合物；小鼠TBK1与两种抑制剂结合的结构；磷酸化的结构 与IRF-3结合的刺激性C端肽；以及IRF-3的仿磷二聚体的结构。这些 全面的结构和功能研究极大地促进了我们对先天的 免疫系统在分子水平上对病毒DNA做出反应。然而，cGAMP如何结合仍是未知的 激活STING，并介导TBK1和IRF-3在信号复合体的招募和激活。在……里面 此外，磷酸化如何诱导IRF-3激活并促进其表达的确切机制 与干扰素-β启动子的关联仍有待确定。在我们强大的初步研究的基础上， 拟议的研究将阐明cGAS-STING途径几个关键步骤的分子基础 目标如下：1)。用STING确定了TBK1招募的结构基础；2)澄清以下问题 CGAMP激活刺痛的分子基础；阐明了TBK1激活IRF-3的机制。这个 建议的研究代表了对胞质DNA机制的严格和全面的研究 并将极大地促进我们对病毒先天免疫的分子基础的理解 感染。此外，它们还为治疗病毒疾病的创新方法提供了一个结构框架， 自身免疫性疾病，以及通过操纵先天免疫反应而患上癌症。