REGULATION OF PHAGOCYTOSIS

白细胞对微生物的吞噬作用代表了一个重要的开端 预防全身感染的定义线。吞噬体 含有病原体的微生物通常通过一系列融合 和裂变反应，涉及内溶酶体的隔室 系统，这导致在敌对的生物体的破坏 吞噬溶酶体的环境。许多病原体，包括致病的 结核病（分枝杆菌）的影响，已经进化出预防机制， 吞噬体成熟为吞噬溶酶体，从而允许它们的 生存我们对这种生物化学机制知之甚少， 调节分裂和融合反应调节吞噬体成熟， 尽管已经假设Rab家族的小G蛋白 磷脂酰肌醇3-激酶（PI 3-kinases）在其中起着重要的作用。 鉴于世界范围内传染病发病率的显著增加， 因此，了解这些疾病的生化机制至关重要。 调节吞噬成熟，以开发合理的治疗 方法。 调节吞噬作用的机制目前正在研究中。 遗传学上易处理的变形虫盘基网柄阿米巴。这些研究 已经揭示了吞噬体成熟的至少4个阶段，包括 一种包含多个颗粒的宽敞吞噬体的形成过程， 被许多细胞内病原体利用。遗传和生化 方法已被用来确定一个GPTase，Rab 7，和PI 3- 激酶DdPIK 1和DdPIK 2似乎调节这一过程。此外，委员会认为， 一种新的Rab，RabB，也在人类细胞中发现，调节吞噬作用。到 确定调节吞噬体的生化机制， 为了促进成熟，提出了以下具体目标。在具体目标#1中， 遗传和生物化学方法将用于：1）确定PI 3- 激酶通过磷酸化吞噬体膜中的脂质直接起作用 以调节同型融合; 2）确定Rab 7和PI 3-激酶是否 功能性偶联和3）鉴定Rab 7效应蛋白。在特定 目的#2，RabB在调节中的作用的生化机制 吞噬作用和吞噬体成熟将被更好地定义。结果 从这些研究应该提供答案，以下重要的 问题：1）Rab 7和PI 3-激酶在功能和物理上 相互作用：2）PI-激酶和Rab 7是否调节细胞内的其他步骤？ 吞噬体成熟途径，除了同型融合：3）什么是 与Rab 7相互作用的效应蛋白的生物化学性质; 4)RabB如何调节颗粒的内化，以及5）如何 RabB在吞噬体途径的其他地方发挥作用？

Phagocytosis of microorganisms by leukocytes represents an important first line of define in the prevention of systemic infections. Phagosomes containing pathogenic organisms are usually modified by a series of fusion and fission reactions, involving compartments of the endo-lysosomal system, which results in the destruction of the organism in the hostile milieu of the phago-lysosome. Many pathogens, including the causative effect of tuberculosis (Mycobacteria), have evolved mechanisms to prevent the maturations of phagosomes to phago-lysosomes, thus allowing for their survival. Little is known concerning the biochemical mechanisms that regulate the fission and fusion reactions regulation phagosome maturation, although it has been hypothesized that the Rab family of small G proteins are phosphatidylinositide 3-kinases (PI 3-kinases) play an important role. Given the significant increase world-wide in the incidence of infectious diseases, it is critical to understand the biochemical mechanisms regulating phagocytosis maturation in order to develop ratione therapeutic approaches. The mechanism regulating phagocytosis are currently being investigated in the genetically tractable amoeba, Dictyostelium discoideum. These studies have revealed at least 4 stages in phagosomal maturation, including the formation of spacious phagosomes containing multiple particles, a process exploited by many intracellular pathogens. Genetic and biochemical approaches have been used to determine that a GPTase, Rab7, and the PI 3- kinases, DdPIK1 and DdPIK2, appear to regulated this process. Furthermore, a novel Rab, RabB, also found in humans cells, regulated phagocytosis. To determine the biochemical mechanisms that operate to regulate phagosomal maturation, the following specific aims are proposed. In specific aim#1, genetic and biochemical approaches will be used to: 1) determine if PI 3- kinases act directly by phosphorylating lipids in the phagosome membrane to regulate homotypic fusion; 2) determine if Rab7 and PI 3-kinases are functionally coupled and 3) identify Rab7 effector proteins. In specific aim #2, the biochemical mechanisms of action of RabB in regulating phagocytosis and phagosomal maturation will be better defined. The results from these studies should supply answers to the following important questions: 1) do Rab7 and PI 3-kinase functionally and physically interact: 2) do PI-kinases and Rab7 regulated other steps in the phagosomal maturation pathway, in addition to homotypic fusion: 3) what is the biochemical nature of the effector proteins that interact with Rab7; 4) how does RabB regulate internalization of particles and 5) how does RabB function elsewhere in the phagosomal pathway?