Characterization of Cytosolic Sensors for mtDNA and Self-DNA in Human Autoimmuni

人类自身免疫中 mtDNA 和自身 DNA 胞质传感器的表征

• 批准号: 8732914
• 负责人: Zhiqiang Zhang
• 金额: $ 14.28万
• 依托单位: BAYLOR RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8732914
• 关键词: APEX1 gene; Autoimmune Diseases; Autoimmunity; Binding; Binding Proteins; Biochemistry; Blood; Cells; Childhood; Complex; Data; Exodeoxyribonuclease I; Fibroblasts; HL60; Human; Immune response; Inflammatory; Inflammatory Response; Inflammatory Response Pathway; Interferon Type I; Interferons; Lead; Lupus; Mammalian Cell; Mediating; Methods; Microbe; Mitochondria; Mitochondrial DNA; Molecular; Molecular Biology; Mutation; Myelogenous; Natural Immunity; Nucleic Acids; Pathway interactions; Patients; Phosphodiesterase I; Play; Production; RNA; Role; Signal Transduction; Source; Structure; Syndrome; Systemic Lupus Erythematosus; TBK1 gene; TREX1 gene; Work; adaptive immunity; base; cytokine; ds-DNA; endonuclease; fighting; monocyte; neutrophil; novel; nuclease; repaired; response; sensor

Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by excess production of type I interferon (IFN) and inflammatory cytokines, as well as by a lack of tolerance to self-nucleic acids, especially double stranded DNA (dsDNA). Evidence suggests that both extra-cellular and intracellular DNA stimulates IFN production in SLE. Indeed, Dr. Pascual's group recently found that oxidized mitochondrial DNA (mtDNA) may be a relevant source of extra-cellular DNA in SLE. While this DNA can be internalized by pDCs to trigger endosomal TLR9 activation and production of IFN, whether the same mtDNA stimulates cytosolic sensors in a cell-autonomous manner is unknown. The 3' repair exonuclease 1, known as TREX1, is the main 3'-^5' exonuclease in mammalian cells and degrades both single-stranded DNA (ssDNA) and dsDNA. TREX1 plays a critical role in removing the store of endogenous DNA to avoid inappropriate sensing and IFN production. Mutations in TREX1 lacking DNA nuclease activity result in Aicardi-Goutieres syndrome and SLE. DNA that accumulates in TREX1 deficient cells signals through STING, but little is known about the cytosolic sensor(s) that respond to this accumulation and connect downstream with the STING pathway. Most nucleic acid cytosolic sensors use adaptors to activate the inflammasome response and MAVS or STING to activate an IFN response. Our studies indicate that DDX41 is the critical cytosolic sensor to recognize dsDNA and trigger the IFN host immune response mediated by STING. Other studies indicate that DDX41 as well as IFI16 play little role in sensing self-DNA. In an effort to identify novel sensors recognizing self-DNA, we isolated and characterized DNA-binding proteins in monocytes and found known as well as novel DNA sensors. Among the latter, the apurinic/ apyrimidinic endonuclease 1, APEX1, works downstream of TREX1 and uses the STING pathway to trigger IFN and inflammatory cytokine responses. Based on our findings, we hypothesize that APEX1 is a critical molecule to sense self DNA in autoimmune diseases such as SLE. Our specific aims will (1) establish the role of APEX1 as a key cytosolic sensor for self-DNA, including mtDNA, in SLE; (2) characterize the role of the APEX1-STING-TBK1 complex in SLE.

系统性红斑狼疮（SLE）是一种自身免疫性疾病，其特征是过量产生 I型干扰素（IFN）和炎症细胞因子，以及对自身核酸缺乏耐受性， 特别是双链DNA（dsDNA）。有证据表明细胞外和细胞内的DNA 刺激SLE中IFN的产生。事实上，帕斯夸尔博士的研究小组最近发现， 线粒体DNA可能是SLE细胞外DNA的一个重要来源。虽然这种DNA可以通过 pDC触发内体TLR 9激活和IFN产生，无论相同的mtDNA刺激 细胞溶质传感器在细胞自主的方式是未知的。3'修复核酸外切酶1，称为TREX 1， 是哺乳动物细胞中主要的3 '-^5'核酸外切酶，降解单链DNA（ssDNA）和 双链DNA TREX 1在去除内源性DNA的储存以避免不适当的细胞凋亡中起着关键作用。 感测和IFN产生。缺乏DNA核酸酶活性的TREX 1突变导致Aicardi-Goutieres 综合征和SLE。在TREX 1缺陷细胞中积累的DNA通过STING发出信号，但很少有 已知细胞溶质传感器响应于这种积累并与下游连接， STING途径。大多数核酸胞质传感器使用衔接子来激活炎性小体反应 和MAVS或STING以激活IFN应答。我们的研究表明，DDX 41是关键的细胞质 传感器识别dsDNA并触发由STING介导的IFN宿主免疫应答。其他研究 表明DDX 41和IFI 16在感应自身DNA中几乎不起作用。为了识别新的传感器 识别自身DNA，我们分离并鉴定了单核细胞中的DNA结合蛋白， 以及新型DNA传感器。在后者中，脱嘌呤/脱嘧啶核酸内切酶1，APEX 1， 在TREX 1的下游，并使用STING途径来触发IFN和炎性细胞因子应答。 基于我们的研究结果，我们假设APEX 1是自身免疫性疾病中感知自身DNA的关键分子， 疾病如SLE。我们的具体目标是（1）建立APEX 1作为关键细胞溶质传感器的作用， 自身DNA，包括mtDNA，在SLE中的作用;（2）表征APEX 1-STING-TBK 1复合物在SLE中的作用。