Role of phosphatidylinositol 3-kinase and Rab5 effectors in phagosomal biogenesis and mycobacterial phagosome maturation arrest.
Role of phosphatidylinositol 3-kinase and Rab5 effectors in phagosomal biogenesis and mycobacterial phagosome maturation arrest.
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磷脂酰肌醇3-激酶和RAB5效应子在吞噬体生物发生和分枝杆菌吞噬体成熟停滞中的作用。
DOI：
10.1083/jcb.200106049
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发表时间：
2001-08-06
影响因子：
7.8
通讯作者：
Deretic, V
中科院分区：
文献类型：
--
作者：
Fratti, R A;Backer, J M;Gruenberg, J;Corvera, S;Deretic, V
吞噬体生物发生是一个基本的生物学过程，对吞噬细胞和抗原提呈细胞的功能具有特别重要的意义。吞噬体成熟为吞噬溶酶体的确切机制尚不完全清楚。在这里，我们利用致病性分枝杆菌在感染巨噬细胞中引起吞噬体成熟停滞的特性，作为分析吞噬体生物发生关键步骤的工具。我们报道了3-磷酸肌苷的需求和Rab5效应早期内体自身抗原（EEA1）的获得是吞噬体成熟所必需的基本分子事件。与含有乳胶珠的模型吞噬体（会短暂招募EEA1）不同，分枝杆菌吞噬体排除了这种控制内体途径内膜系结和融合过程的囊泡运输调节剂，并通过与磷脂酰肌醇3-磷酸（PtdIns[3]P）结合被招募到内体膜上。磷脂酰肌醇3′(OH)-激酶（PI-3K）活性抑制剂可减少EEA1向新形成的胶乳头吞噬体的募集，并阻断吞噬体获得晚期内吞特性，表明PtdIns(3)P的产生在吞噬体成熟中起作用。在巨噬细胞中微量注射EEA1和PI-3K hVPS34抗体，可减少乳胶珠吞噬体获取晚期内吞标记物，证明这些Rab5效应物在吞噬体生物发生中的重要作用。用分枝杆菌产物研究了EEA1在分枝杆菌吞噬体中的排斥作用机制。用从结核分枝杆菌H37Rv中分离出来的糖基化磷脂酰肌醇脂阿拉伯糖甘露聚糖包覆乳珠，抑制EEA1向乳珠吞噬体的募集，并减少其成熟。这些发现将磷脂酰肌醇3-磷酸的产生和EEA1的募集定义为：(a)吞噬体成熟过程中的重要调控事件和(b)受结核分枝杆菌影响的关键分子靶点。本研究还确定分枝杆菌磷酸肌苷是具有特殊毒性的产物，干扰吞噬体成熟过程中的离散运输阶段。
Phagosomal biogenesis is a fundamental biological process of particular significance for the function of phagocytic and antigen-presenting cells. The precise mechanisms governing maturation of phagosomes into phagolysosomes are not completely understood. Here, we applied the property of pathogenic mycobacteria to cause phagosome maturation arrest in infected macrophages as a tool to dissect critical steps in phagosomal biogenesis. We report the requirement for 3-phosphoinositides and acquisition of Rab5 effector early endosome autoantigen (EEA1) as essential molecular events necessary for phagosomal maturation. Unlike the model phagosomes containing latex beads, which transiently recruited EEA1, mycobacterial phagosomes excluded this regulator of vesicular trafficking that controls membrane tethering and fusion processes within the endosomal pathway and is recruited to endosomal membranes via binding to phosphatidylinositol 3-phosphate (PtdIns[3]P). Inhibitors of phosphatidylinositol 3′(OH)-kinase (PI-3K) activity diminished EEA1 recruitment to newly formed latex bead phagosomes and blocked phagosomal acquisition of late endocytic properties, indicating that generation of PtdIns(3)P plays a role in phagosomal maturation. Microinjection into macrophages of antibodies against EEA1 and the PI-3K hVPS34 reduced acquisition of late endocytic markers by latex bead phagosomes, demonstrating an essential role of these Rab5 effectors in phagosomal biogenesis. The mechanism of EEA1 exclusion from mycobacterial phagosomes was investigated using mycobacterial products. Coating of latex beads with the major mycobacterial cell envelope glycosylated phosphatidylinositol lipoarabinomannan isolated from the virulent Mycobacterium tuberculosis H37Rv, inhibited recruitment of EEA1 to latex bead phagosomes, and diminished their maturation. These findings define the generation of phosphatidylinositol 3-phosphate and EEA1 recruitment as: (a) important regulatory events in phagosomal maturation and (b) critical molecular targets affected by M. tuberculosis. This study also identifies mycobacterial phosphoinositides as products with specialized toxic properties, interfering with discrete trafficking stages in phagosomal maturation.