权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

REGULATION OF PHAGOCYTOSIS

吞噬作用的调节

基本信息

批准号：
6380580
负责人：
JAMES CARDELLI
金额：
$ 18.53万
依托单位：
LOUISIANA STATE UNIV HSC SHREVEPORT
依托单位国家：
美国
项目类别：
财政年份：
1988
资助国家：
美国
起止时间：
1988-01-01 至 2003-06-30
项目状态：
已结题

项目摘要

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?

白细胞对微生物的吞噬作用代表了重要的第一预防全身感染的定义线。吞噬体含有致病生物体通常是通过一系列融合来修饰的和裂变反应，涉及内溶酶体的区室系统，导致敌对生物体的破坏吞噬溶酶体的环境。许多病原体，包括致病菌结核病（分枝杆菌）的影响，已进化出预防机制吞噬体成熟为吞噬溶酶体，从而允许它们生存。关于其生化机制知之甚少调节裂变和融合反应调节吞噬体成熟，尽管有人假设小 G 蛋白的 Rab 家族磷脂酰肌醇3-激酶（PI 3-激酶）发挥重要作用。鉴于世界范围内传染病发病率显着增加疾病的发生，了解其生化机制至关重要调节吞噬作用成熟以开发合理的治疗方法接近。目前正在研究调节吞噬作用的机制遗传上易驯化的阿米巴原虫，盘基网柄菌（Dictyostelium discoideum）。这些研究揭示了吞噬体成熟的至少 4 个阶段，包括包含多个颗粒的宽敞吞噬体的形成，一个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 GPTase、Rab7 和 PI 3- 激酶 DdPIK1 和 DdPIK2 似乎调节这一过程。此外，在人类细胞中也发现了一种新的 Rab，RabB，它可以调节吞噬作用。到确定调节吞噬体的生化机制成熟后，提出以下具体目标。在具体目标#1中，遗传和生化方法将用于： 1) 确定 PI 3- 激酶通过磷酸化吞噬体膜中的脂质直接发挥作用调节同型融合； 2) 确定 Rab7 和 PI 3-激酶是否功能耦合，3) 鉴定 Rab7 效应蛋白。具体来说目标#2，RabB 调节作用的生化机制吞噬作用和吞噬体成熟将得到更好的定义。结果这些研究应该为以下重要问题提供答案问题：1) Rab7 和 PI 3-激酶的功能和物理功能相互作用：2) PI 激酶和 Rab7 是否调节细胞中的其他步骤？吞噬体成熟途径，除了同型融合之外：3）什么是与 Rab7 相互作用的效应蛋白的生化性质； 4) RabB 如何调节粒子的内化以及 5) 如何调节粒子的内化 RabB 在吞噬体途径的其他地方发挥作用？