Mechanism of M. tuberculosis Phagosome Maturation Arrest

描述（由申请人提供）：结核分枝杆菌感染大量人群的能力，加上艾滋病中多药耐药性和机会性感染的广泛出现，导致其被列入NIAID生物防御和新发感染性病原体名单。结核分枝杆菌在人群中的持久性取决于其感染巨噬细胞并在巨噬细胞中存活的能力。细胞内结核分枝杆菌抑制吞噬体成熟，并驻留在病原体友好的吞噬体中，逃避溶酶体的杀菌机制和有效的抗原呈递。该项目的长期目标是表征结核分枝杆菌吞噬体成熟阻滞的分枝杆菌产物，并确定分枝杆菌因子靶向的宿主细胞膜运输过程。这些现象与分枝杆菌干扰宿主细胞Rab gtp酶控制的膜运输和细胞器生物发生过程有关。我们假设结核分枝杆菌干扰特定的Rab相互作用伙伴，包括一种Rab效应物，磷脂酰肌醇3-激酶，它使吞噬体准备与其他细胞器系住和融合。该假说的一个组成部分是结核分枝杆菌脂类，其模拟哺乳动物磷脂酰肌醇，通过干扰宿主细胞中磷脂酰肌醇3-激酶依赖过程影响细胞器融合和吞噬体成熟。具体目标是：1。鉴定结核分枝杆菌影响吞噬体成熟的脂质和蛋白产物并确定其作用方式。2. 描述包括Rab5效应物在内的宿主细胞膜运输调节因子在结核分枝杆菌吞噬体成熟阻滞中的作用。3. 表征新的，基于细胞生物学的过程，可以抵消结核分枝杆菌吞噬体成熟阻滞。这种三管齐下的方法将提高我们对结核分枝杆菌的主要致病决定因素的理解，并为潜在地对抗活动性疾病和潜伏性感染的新干预措施提供基础。

DESCRIPTION (provided by applicant): The ability of Mycobacterium tuberculosis to infect an extraordinary number of people, combined with the widespread emergence of multidrug resistance and opportunistic infections in AIDS, has lead to its placement on the NIAID list of biodefense and emerging infectious agents. M. tuberculosis persistence in human populations rests upon its ability to infect and survive in macrophages. Intracellular M. tuberculosis inhibits phagosomal maturation and resides in a pathogen-friendly phagosome escaping lysosomal bactericidal mechanisms and efficient antigen presentation. The long-term objectives of this project are to characterize mycobacterial products responsible for the M. tuberculosis phagosomal maturation block and identify the host cell membrane trafficking processes that are targeted by the mycobacterial factors. These phenomena have been linked to mycobacterial interference with membrane trafficking and organelle biogenesis processes controlled by host cell Rab GTPases. We hypothesize that M. tuberculosis interferes with specific Rab-interacting partners, including a Rab effector, phosphatidylinositol 3-kinase, that prepares phagosomes for tethering and fusion with other organelles. An integral part of this hypothesis is that M. tuberculosis lipids, which mimic mammalian phosphatidylinositols, affect organellar fusion and phagosomal maturation by interfering with phosphatidylinositol 3-kinase-dependent processes in the host cell. The specific aims are: 1. Identify M. tuberculosis lipid and protein products affecting phagosome maturation and characterize their mode of action. 2. Delineate the role of host cell membrane trafficking regulators including Rab5 effectors in M. tuberculosis phagosome maturation arrest. 3. Characterize novel, cell biology-based processes that can counteract M. tuberculosis phagosome maturation arrest. This three-prong approach will improve our understanding of a marquee pathogenic determinant of M. tuberculosis and provide a foundation for new interventions potentially combating both active disease and latent infection.