Regulation of Legionella pneumophila pathogenesis by the central eukaryotic metabolic checkpoint kinase Mechanistic Target of Rapamycin (MTOR)

中央真核代谢检查点激酶雷帕霉素 (MTOR) 调节嗜肺军团菌发病机制

• 批准号: 10329977
• 负责人: Stanimir Stefanov Ivanov
• 金额: $ 36.5万
• 依托单位: LOUISIANA STATE UNIV HSC SHREVEPORT
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-02-11 至 2024-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10329977
• 关键词: Agonist; Alveolar Macrophages; Anabolism; Autophagocytosis; Bacterial Infections; Binding; Binding Proteins; Biochemical; Biochemical Genetics; Catabolism; Cells; Cytosol; Defense Mechanisms; Etiology; Eukaryota; Eukaryotic Cell; Event; Evolution; FRAP1 gene; Homeostasis; Host Defense; Human; IL6 gene; Immune; Immune response; Immunity; Infection; Inflammation; Inflammatory; Inflammatory Response; Innate Immune System; Interleukin-10; Interleukin-12; Interruption; Invaded; Knowledge; Legionella; Legionella pneumophila; Legionnaires' Disease; Link; Lipids; Lung; Maintenance; Mediating; Membrane; Metabolic; Metabolism; Microbe; Molecular; Organelles; Parasites; Pathogenesis; Pathogenicity; Pathway interactions; Phosphotransferases; Process; Protein-Serine-Threonine Kinases; Proteins; Proteolysis; Protozoa; Regulation; Regulatory Element; Rupture; Shapes; Sterols; System; TNF gene; Testing; Toxin; Training; Ubiquitin; Virulence; Virulent; Work; antimicrobial; atypical pneumonia; base; cytokine; design; genetic approach; imaging approach; immune system function; insight; lipid biosynthesis; macrophage; mutant; novel; pathogen; pathogenic bacteria; programs; receptor; respiratory; respiratory pathogen; response; sensor; transcription factor; ubiquitin ligase

The work proposed here seeks to investigate the mechanism by which mammalian macrophages suppress the metabolic checkpoint kinase Mechanistic target of rapamycin (MTOR) to promote immune defenses and counteract anabolic reprogramming by the vacuolar pathogen Legionella pneumophila. MTOR is a universally conserved master switch regulating catabolism to anabolism transition in eukaryotic cells. Vacuolar pathogens rely on host metabolites not only for bacterial replication but also for maintenance of their intracellular niches. The human respiratory pathogen Legionella pneumophila is a prototypical vacuolar pathogen that infects and replicates within mammalian macrophages. We uncovered that Legionella stimulates host membrane biosynthesis to expand its niche by subverting MTOR. However, a host suppression pathway counteracts L. pneumophila-induced MTOR activation by targeting MTOR for ubiquitin-dependent proteolysis. In macrophages, MTOR suppression promotes cell intrinsic (autophagy) and cell extrinsic (inflammation) host defenses. Specifically, pathogenic L. pneumophila expressing the type IVb secretion system (T4bSS) but not the avirulent mutants lacking a functional T4bSS elicited the host MTOR suppression response. Thus, we hypothesize that in mammalian macrophages MTOR functions downstream of homeostatic mechanisms that sense the pathogenic potential of invading microbes to potentiate host defenses. Such mechanisms operate by detecting virulence adaptations encoded by bacterial pathogens (such as specialized secretion systems and secreted toxins), which frequently produce pathogen-specific signatures. In the first aim we will determine the mechanism by which Legionella subverts MTOR function, when the host suppression pathway is inactivated. In the second aim we are going to use biochemical and genetic approaches to determine how the Legionella intracellular niche is controlled by host metabolic regulators. Our third aim is to elucidate how the pathogen signature that elicits MTOR suppression is generated. To this end, we will perform a systematic analysis of the Legionella intracellular niche using a variety of imaging approaches to define the early events that trigger MTOR suppression.

这里提出的工作旨在调查哺乳动物的机制 巨噬细胞抑制雷帕霉素的代谢检查点激酶机械靶标 （MTOR）促进免疫防御和抵消液泡的合成代谢重编程 病原体肺炎。 MTOR是一种普遍保守的主开关调节 对真核细胞中代谢过渡的分解代谢。液泡病原体依赖宿主 代谢物不仅用于细菌复制，而且还用于维持其细胞内 利基。人类呼吸道病原体肺炎是一种典型的液泡 在哺乳动物巨噬细胞中感染和复制的病原体。我们发现了这一点 军团菌刺激宿主膜的生物合成，通过颠覆MTOR来扩展其利基市场。 然而，宿主抑制途径抵消了肺炎乳杆菌诱导的mTOR激活 靶向MTOR用于泛素依赖性蛋白水解。在巨噬细胞中，mtor抑制 促进细胞固有（自噬）和细胞外部（炎症）宿主防御能力。具体来说， 表达IVB型分泌系统（T4BS）的致病性肺炎乳杆菌，但不是 缺乏功能性T4BS的无毒突变体引起了宿主MTOR抑制反应。 因此，我们假设在哺乳动物巨噬细胞中MTOR的功能下游 稳态机制感知入侵微生物增强的致病潜力 主机防御。这种机制是通过检测由毒力适应所编码的 细菌病原体（例如专业分泌系统和分泌的毒素）， 经常产生病原体特异性签名。在第一个目标中，我们将确定 当主机抑制途径为 灭活。在第二个目标中，我们将使用生化和遗传学方法 确定寄主代谢调节剂如何控制军团菌的细胞内生态位。我们的 第三个目的是阐明引起mtor抑制的病原体特征是如何 生成。为此，我们将对小军团菌的细胞内小裂进行系统分析 使用各种成像方法来定义触发mTOR的早期事件 抑制。