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.

全身性红斑狼疮（SLE）是一种自身免疫性疾病，其特征是产生过多 I型干扰素（IFN）和炎症细胞因子，以及缺乏对自核酸的耐受性， 特别是双链DNA（dsDNA）。有证据表明细胞外和细胞内DNA 刺激SLE的IFN产生。确实，帕斯卡尔博士的小组最近发现氧化了线粒体 DNA（mtDNA）可能是SLE中细胞外DNA的相关来源。虽然该DNA可以通过 PDC触发内体TLR9激活和IFN的产生，同一mtDNA是否刺激 以细胞自治方式的胞质传感器是未知的。 3'维修外切酶1，称为TREX1， 是哺乳动物细胞中的主要3' - ^5'外切酶，并降解单链DNA（ssDNA）和 dsdna。 TREX1在去除内源性DNA的存储中起着至关重要的作用 感知和IFN产生。缺乏DNA核酸酶活性的Trex1突变导致AICARDI-GOTIERES 综合征和SLE。通过刺痛积聚在Trex1缺陷细胞信号中的DNA，但几乎没有 知道对这种积累的响应并与下游连接的胞质传感器 sting路。大多数核酸胞质传感器都使用适配器激活炎性体反应 和MAV或刺痛以激活IFN响应。我们的研究表明DDX41是关键的胞质 传感器识别dsDNA并触发通过刺激介导的IFN宿主免疫反应。其他研究 表明DDX41以及IFI16在感测自DNA中起很少作用。为了识别新型传感器 识别自DNA，我们在单核细胞中分离并表征了DNA结合蛋白，并发现已知 以及新型的DNA传感器。在后者中，源自/肾上腺素核酸内切酶1，apex1，作品 TREX1的下游并使用刺激途径来触发IFN和炎症细胞因子反应。 根据我们的发现，我们假设Apex1是在自身免疫中感知自DNA的关键分子 诸如SLE之类的疾病。我们的具体目的（1）将APEX1作为关键的胞质传感器的作用 SLE中的自我DNA，包括mtDNA； （2）表征Apex1-Sting-TBK1复合物在SLE中的作用。