Elucidating the Structural Mechanisms of NAIP Receptors in Bacterial Detection and Inflammasome Activation

阐明 NAIP 受体在细菌检测和炎症小体激活中的结构机制

• 批准号: 10338540
• 负责人: Liman Zhang
• 金额: $ 36.03万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-12-10 至 2026-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10338540
• 关键词: Address; Advanced Development; Apoptosis; Architecture; Bacteria; Bacterial Proteins; Binding; Binding Sites; Biochemical; CASP1 gene; Caspase; Cell Death; Cell membrane; Cell surface; Cells; Clinical Drug Development; Communicable Diseases; Complex; Cryoelectron Microscopy; Data; Detection; Development; Disease; Environment; Exhibits; Family; Flagellin; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Human; Immune response; Immunologic Receptors; Inflammasome; Inflammation; Inflammatory; Innate Immune System; Interleukin-1; Interleukin-18; Interphase Cell; Learning; Legionella pneumophila; Leucine-Rich Repeat; Ligand Binding; Ligands; Macrophage activation syndrome; Malignant Neoplasms; Metabolic Diseases; Modeling; Molecular; Molecular Conformation; Mus; Mutation; Mutation Analysis; N-terminal; Needles; Nucleotides; Pathogenicity; Pathway interactions; Play; Process; Protein Family; Proteins; Reaction; Regulation; Reporting; Research; Resolution; Rod; Role; Salmonella; Salmonella typhimurium; Science; Signal Transduction; Specificity; Spinal Muscular Atrophy; Structure; Testing; Type III Secretion System Pathway; Work; autoinflammation; autoinflammatory; base; cytokine; dalton; delta protein; effective therapy; extracellular; insight; novel; novel therapeutic intervention; pathogen; polymerization; prevent; protein complex; receptor; recruit; response

Project Summary Inflammasomes are mega-Dalton protein complexes that initiate inflammation responses and play important roles in the innate immune system. Upon activation, inflammasomes recruit and activate the effector protein caspase-1. Caspase-1 in turn cleaves the Gasdermin D (GSDMD) protein to release its N-terminal domain, which inserts into the cell membrane to punch holes on the cell surface. As a result, the host cell will undergo pyroptotic cell death (pyroptosis) and release the cell contents into the extracellular environment. Pro-inflammatory cytokines IL-1 and IL-18, both activated by caspase-1, will also be released to activate the downstream inflammation reactions. NAIP is a family of cytosolic immunological receptors that activate the NAIP/NLRC4 inflammasomes in response to Gram-negative bacterial infections. There are seven NAIP proteins in mouse, each sense a specific ligand such as Flagellin, Needle protein or Inner Rod protein in the type III secretion system. In previous studies, we have shown active NAIPs activate NLRC4 through the nucleated polymerization mechanism. However, it is still largely unknown about how NAIPs remain inactive in the resting cells, and how is the ligand specificity is determined among different NAIPs. Unlike in mouse, humans only have one NAIP and it was shown to be activated by all three bacterial ligands. This leads to many questions including what is the structural basis of the broad detection of bacterial ligands by human NAIP and what does it tell us about the human inflammasomal bacterial detection mechanism? To address these questions, we propose to combine electron cryo-microscopy (cryoEM) with biochemical and functional studies to elucidate the structural mechanisms underlying the signal transduction by NAIP proteins. Dysregulation of NAIP/NLRC4 inflammasomes causes macrophage activation syndrome (MAS) and autoinflammation, and mutations of NAIP protein are highly correlated with spinal muscular atrophy (SMA). The successful execution of this work will broadly advance the development of effective therapies to treat infectious diseases, autoinflammatory diseases, SMA, and cancer through targeting the inflammasome pathway.

项目概要 炎症小体是巨型道尔顿蛋白复合物，可引发炎症反应并发挥重要作用 在先天免疫系统中的作用。激活后，炎症小体招募并激活效应蛋白 胱天蛋白酶-1。 Caspase-1 依次裂解 Gasdermin D (GSDMD) 蛋白以释放其 N 末端结构域，从而 插入细胞膜，在细胞表面打孔。结果，宿主细胞将发生焦亡 细胞死亡（焦亡）并将细胞内容物释放到细胞外环境中。促炎性 细胞因子IL-1和IL-18均被caspase-1激活，也会被释放以激活下游 炎症反应。 NAIP 是细胞质免疫受体家族，可激活 NAIP/NLRC4 炎症小体 对革兰氏阴性细菌感染的反应。小鼠体内有七种 NAIP 蛋白，每种蛋白感知特定的 III型分泌系统中的配体，例如鞭毛蛋白、针蛋白或内杆蛋白。在之前的研究中， 我们已经证明活性 NAIP 通过成核聚合机制激活 NLRC4。然而，它是 关于 NAIP 如何在静息细胞中保持非活性，以及​​配体特异性如何，目前仍知之甚少。 不同 NAIP 之间确定。与小鼠不同，人类只有一种 NAIP，并且被证明 由所有三种细菌配体激活。这引发了许多问题，包括其结构基础是什么？ 人类 NAIP 对细菌配体的广泛检测以及它告诉我们关于人类炎症小体的什么信息 细菌检测机制？为了解决这些问题，我们建议结合电子冷冻显微镜 (cryoEM) 通过生化和功能研究来阐明信号背后的结构机制 NAIP 蛋白的转导。 NAIP/NLRC4 炎症小体失调导致巨噬细胞激活 综合征（MAS）和自身炎症，NAIP蛋白突变与脊髓肌肉损伤高度相关 萎缩（SMA）。这项工作的成功执行将广泛推动有效疗法的开发 通过靶向炎症小体来治疗传染病、自身炎症性疾病、SMA 和癌症 途径。