Regulation of IFN-g-induced Innate Immunity by LRG-47

LRG-47 对 IFN-g 诱导的先天免疫的调节

• 批准号: 6709981
• 负责人: GREGORY A TAYLOR
• 金额: $ 37.01万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6709981
• 关键词: Salmonella typhimurium; active sites; antibacterial agents; antiprotozoal agents; bacterial disease; biological transport; bioterrorism /chemical warfare; catalyst; chemical kinetics; endocytosis; enzyme activity; enzyme induction /repression; enzyme mechanism; genetic manipulation; genetically modified animals; guanosinetriphosphatases; host organism interaction; immunity; interferon gamma; intracellular; laboratory mouse; lysosomes; macrophage; protein localization; protein structure function; tissue /cell culture; vesicle /vacuole

DESCRIPTION (provided by applicant): Recently, a new family of IFN-gamma-induced p47 GTPases has been identified that is essential for innate immunity against intracellular pathogens. Knock-out (KO) mouse studies have shown that three of these proteins (LRG-47, IGTP, and IRG-47) are critical for resistance to multiple category A, B, and C biodefense priority pathogens. In particular, LRG-47, but not IGTP or IRG-47, is absolutely required for resistance to the intracellular bacteria Salmonella typhimurium, Mycobacterium tuberculosis, Listeria monocytogenes, and Francisella tularensis. In contrast, all three proteins are required for resistance to the protozoan parasite Toxoplasma gondii. The underlying mechanism for the antibacterial actions of LRG-47 is unknown. It is hypothesized here that LRG-47 regulates host resistance to intracellular bacteria by promoting IFN-gamma-induced bacterial killing in macrophages. It is further hypothesized that the protein localizes to the early endosomal compartment, where it catalyzes endosomal fusion with nascent bacteria-containing phagosomes, promoting phagosomal maturation and bacterial killing. In contrast, it is proposed that IGTP and IRG-47 localize to lysosomes and catalyze different facets of phagosomal processing. These hypotheses will be tested with the following aims: Aim I. The subcellular mechanism that underlies the impaired ability of LRG-47 KO macrophages to elicit IFN-gamma-induced bacterial killing will be defined, by determining: (a) the precise localization of LRG-47 within endosomal compartments; (b) the kinetics of LRG-47 trafficking to S. typhimurium-containing phagosomes; and (c) the effect of LRG-47 on maturation of the phagosome maturation, including lysosomal fusion, phagosomal acidification, and trafficking of endosomal markers. Aim II. Molecular domains of LRG-47 that determine its activity will be defined. Extensive mutational analysis and functional assays will define domains required for: (a) association with endosomes and trafficking to phagosomes; (b) endosome/phagosome fusion; (c) modulation of phagosomal maturation; and (d) bacterial killing in cultured macrophages and in vivo. Thus, this research will elucidate a mechanism that is critical for IFN-gamma- induced innate resistance to intracellular bacteria, with the ultimate goal of creating broadly effective anti-bacterial agents for biodefense.

描述（由申请人提供）：最近，已经确定了一个新的IFN-GAMMA诱导的P47 GTPases家族，这对于对抗细胞内病原体的先天免疫力至关重要。敲除（KO）小鼠研究表明，其中三种蛋白质（LRG-47，IGTP和IRG-47）对于对多个类别A，B和C Biodefense Primits Priority Partogens的抗性至关重要。尤其是耐药性细菌鼠伤寒沙门氏菌，结核分枝杆菌，单核细胞增生李斯特菌和francisella toarlensels绝对需要LRG-47，但不是IGTP或IRG-47。相比之下，所有三种蛋白质都需要对原生动物寄生虫弓形虫的抗性。 LRG-47抗菌作用的基本机制尚不清楚。在这里假设LRG-47通过促进巨噬细胞中IFN-GAMMA诱导的细菌杀伤来调节宿主对细胞内细菌的耐药性。进一步假设该蛋白质定位于早期内体室，在那里它与含有新生细菌的吞噬体催化内体融合，从而促进吞噬体成熟和细菌杀伤。相比之下，提议IGTP和IRG-47局部局部呈溶酶体并催化吞噬体加工的不同方面。这些假设将通过以下目的进行测试： AIM I.将通过确定：（a）内体隔室内LRG-47的精确定位来定义LRG-47 KO巨噬细胞引起IFN-GAMMA诱导的细菌杀伤能力受损能力受损能力受损能力的亚细胞机制； （b）LRG-47贩运孢子菌的动力学的动力学； （c）LRG-47对吞噬体成熟成熟的影响，包括溶酶体融合，吞噬体酸化和内体标记的运输。 目标II。确定其活性的LRG-47的分子结构域将被定义。广泛的突变分析和功能测定将定义以下区域所需的域：（a）与内体和贩运与吞噬体的关联； （b）内体/吞噬体融合； （c）调节吞噬体成熟； （d）在培养的巨噬细胞和体内杀死细菌。 因此，这项研究将阐明一种机制，对于IFN-GAMMA诱导的对细胞内细菌的抗性至关重要，其最终目标是为生物脱脂素创造广泛有效的抗细菌剂。