Negative regulation of innate immune signaling pathways by the selective autophagy receptor TAX1BP1

选择性自噬受体 TAX1BP1 对先天免疫信号通路的负调节

• 批准号: 10797470
• 负责人: EDWARD W HARHAJ
• 金额: $ 6.68万
• 依托单位: PENNSYLVANIA STATE UNIV HERSHEY MED CTR
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10797470
• 关键词: Adaptor Signaling Protein; Apoptosis; Apoptotic; Automobile Driving; Autophagocytosis; Autophagosome; CASP1 gene; Cell Death; Cell membrane; Cells; DNA; Double-Stranded RNA; Endoplasmic Reticulum; Genes; Homeostasis; Host Defense; IRF3 gene; Immune; Immune response; Immune signaling; Inflammasome; Inflammation; Inflammatory; Inflammatory Response; Interferon Type I; Invaded; Investigation; Lytic; Macrophage; Mediating; Membrane; Mitochondria; Molecular; NF-kappa B; Natural Immunity; Pathway interactions; Pattern; Pattern recognition receptor; Phosphorylation; Phosphotransferases; Play; Production; Proteins; RNA Helicase; Regulation; Role; Signal Pathway; Signaling Protein; Stimulator of Interferon Genes; TBK1 gene; Testing; Tissues; Viral Genome; Virus; Work; Zinc Fingers; adaptive immune response; adaptive immunity; cytokine; ds-DNA; immunoregulation; inhibitor; insight; novel; pathogen; pathogenic microbe; protein aggregation; receptor; recruit; response; sensor; ubiquitin isopeptidase

ABSTRACT Innate immunity provides the first line of host defense in response to invading pathogens. Pattern recognition receptors (PRRs) sense pathogen-associated molecular patterns (PAMPs) in viruses and other pathogens. RIG-I/MDA-5 are DExD/H box RNA helicases in the RIG-I-like receptor (RLR) pathway that detect double stranded RNA viral genomes and activate the mitochondrial adaptor protein MAVS. The DNA sensor cGAS detects double stranded DNA and activates STING, a transmembrane endoplasmic reticulum adaptor. Both MAVS and STING activate canonical (IKKa and IKKb), and noncanonical IKK kinases (TBK1 and IKKi) to activate transcription factors NF-kB and IRF3 respectively. Together, IRF3 and NF-kB regulate the expression of type I interferon (IFN) and inflammatory genes that coordinate the innate response and initiate the adaptive immune response against pathogens. The NLRP3 inflammasome also plays a critical role in inflammatory responses by triggering caspase-1-mediated pro-IL-1b cleavage to yield the biologically active form of IL- 1b that drives inflammation and adaptive immunity. NLRP3 also induces a highly lytic form of inflammatory cell death termed pyroptosis via cleavage of gasdermin-D to form plasma membrane pores. The RLR, cGAS- STING and NLRP3 inflammasome pathways are potent inducers of inflammation that must be tightly regulated to avert overexuberant inflammation and tissue damage. TAX1BP1 was first identified as an anti-apoptotic protein that interacts with the zinc finger deubiquitinase A20/TNFAIP3. Our previous work has established that TAX1BP1 restricts cytokine-induced NF-kB activation as well as RLR-induced type I IFN production and apoptosis. TAX1BP1 functions as a selective autophagy receptor by recruiting ubiquitinated cargo to developing autophagosomes via two LC3 interaction regions (LIRs). However, it remains unclear how TAX1BP1 autophagy function is regulated and if TAX1BP1 inhibits other innate immune signaling pathways. In preliminary studies we provide experimental evidence that TAX1BP1 is phosphorylated by both noncanonical and canonical IKK kinases which controls both basal and virus-induced TAX1BP1 autophagic degradation respectively. Using TAX1BP1-deficient macrophages we have demonstrated that TAX1BP1 is a novel inhibitor of both cGAS-STING and NLRP3 pathways. Furthermore, MAVS protein aggregates accumulate in TAX1BP1- deficient cells suggesting a potential aggrephagy function in the regulation of innate immune signaling. The central hypothesis driving the proposed investigations is that TAX1BP1 inhibits RLR, cGAS-STING and NLRP3 pathways by autophagy-mediated clearance of signaling protein aggregates. We will test this hypothesis experimentally with the following Specific Aims: (1) determine the role of TAX1BP1 phosphorylation in its autophagy function, (2) determine the mechanisms of TAX1BP1 inhibition of the cGAS-STING pathway, and (3) determine the mechanisms of TAX1BP1 inhibition of the NLRP3 pathway. Completion of the proposed studies will provide new insights into innate immune regulation and immune homeostasis.

抽象的 先天免疫提供了宿主应对入侵病原体的第一道防线。模式识别 受体（PRR）感知病毒和其他病原体中的病原体相关分子模式（PAMP）。 RIG-I/MDA-5 是 RIG-I 样受体 (RLR) 通路中的 DExD/H 盒 RNA 解旋酶，可检测双 链RNA病毒基因组并激活线粒体接头蛋白MAVS。 DNA 传感器 cGAS 检测双链 DNA 并激活 STING（一种跨膜内质网接头）。两个都 MAVS 和 STING 激活经典（IKKa 和 IKKb）和非经典 IKK 激酶（TBK1 和 IKKi） 分别激活转录因子 NF-kB 和 IRF3。 IRF3 和 NF-kB 共同调节表达 I 型干扰素 (IFN) 和炎症基因协调先天反应并启动适应性 针对病原体的免疫反应。 NLRP3炎症小体在炎症反应中也发挥着关键作用 通过触发 caspase-1 介导的 pro-IL-1b 裂解产生具有生物活性形式的 IL- 1b 驱动炎症和适应性免疫。 NLRP3 还诱导高度溶解形式的炎症细胞 通过gasdermin-D 裂解形成质膜孔而导致的死亡被称为细胞焦亡。 RLR、cGAS- STING 和 NLRP3 炎症小体通路是炎症的有效诱导物，必须受到严格调控 以避免过度炎症和组织损伤。 TAX1BP1 首次被鉴定为抗凋亡药物 与锌指去泛素酶 A20/TNFAIP3 相互作用的蛋白质。我们之前的工作已经确定 TAX1BP1 限制细胞因子诱导的 NF-kB 激活以及 RLR 诱导的 I 型 IFN 产生和 细胞凋亡。 TAX1BP1 通过招募泛素化货物来发挥选择性自噬受体的作用 通过两个 LC3 相互作用区域 (LIR) 形成自噬体。然而，目前尚不清楚如何 如果 TAX1BP1 抑制其他先天免疫信号通路，则 TAX1BP1 自噬功能受到调节。在 初步研究我们提供了 TAX1BP1 被非规范磷酸化的实验证据 以及控制基础和病毒诱导的 TAX1BP1 自噬降解的经典 IKK 激酶 分别。使用 TAX1BP1 缺陷型巨噬细胞，我们证明了 TAX1BP1 是一种新型抑制剂 cGAS-STING 和 NLRP3 通路。此外，MAVS 蛋白聚集体在 TAX1BP1- 中积累 缺陷细胞表明在先天免疫信号调节中具有潜在的聚合吞噬功能。这 推动拟议研究的中心假设是 TAX1BP1 抑制 RLR、cGAS-STING 和 NLRP3 通过自噬介导的信号蛋白聚集体清除途径。我们将检验这个假设 实验具有以下具体目标：（1）确定 TAX1BP1 磷酸化在其 自噬功能，(2) 确定 TAX1BP1 抑制 cGAS-STING 通路的机制，以及 (3)确定TAX1BP1抑制NLRP3通路的机制。完成拟议的 研究将为先天免疫调节和免疫稳态提供新的见解。