Role of sphingosine kinase and sphingolipids in phagosome biology relevant for pathogenic mycobacteria infection in macrophages

鞘氨醇激酶和鞘脂在与巨噬细胞致病性分枝杆菌感染相关的吞噬体生物学中的作用

• 批准号: 37702489
• 负责人: Professor Gareth Griffiths, Ph.D.
• 金额: --
• 依托单位: Department of Molecular Biosciences
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/37702489?language=en
• 关键词: Role; sphingosine; kinase; sphingolipids; phagosome

Sphingosine kinase converts sphingosine (Sp) to sphingosine-1-phosphate (S1P). Sp kinase acts as a switch since substrate and product have opposite effects on cells; Sp for example promotes apoptosis, while S1 P favours cell survival. We showed that Sp kinase activity is present in membranes of latex bead phagosomes (LBP) isolated from 1 macrophages; there, high Sp inhibits membrane-catalysed actin assembly, which S1P stimulates. In macrophages, high S1P favours killing of mycobacteria enclosed in phagosomes, a pro-inflammatory response linked to actin assembly, while Sp behaves as an anti-inflammatory factor favouring mycobacterial growth. The ability of pathogenic mycobacteria such as M.tuberculosis to block the fusion of its phagosomes with lysosomes was recently shown to be dependent on their ability to inhibit Sp kinase. The goal here is to characterize Sp kinase on isolated phagosomes and phagosomes in macrophages in more detail. These analyses will be facilitated by using GFP-Sp kinase constructs and by RNAi experiments to selectively remove Sp kinase and its inter-linked molecules. LBP actin assembly is dependent on ezrin and P14,5P2 and is regulated by PLD. From the literature Sp Kinase binds directly to PLD, while PLD itself binds both Gactin, which inhibits its activity, and F-actin, which stimulates PLD. Sp kinase also indirectly binds PKA while cAMP/PKA inhibit phagosome actin assembly. These interactions have not all been analysed in one cell system. The isolated LBP and phagosomes inside macrophages are attractive systems to decipher the role of sphingolipids in a defined membrane process, actin assembly- that appears to be part of the pro-inflammatory response. This is relevant for killing pathogenic mycobacteria and modulation of sphingosine kinase activity could be considered as a therapeutic approach against these pathogens.

鞘氨醇激酶将鞘氨醇(Sp)转化为鞘氨醇-1-磷酸(S1P)。由于底物和产物对细胞有相反的作用，SP激酶起着开关的作用；例如，Sp促进细胞凋亡，而S1P有利于细胞存活。我们发现，从1个巨噬细胞分离的胶乳微珠吞噬体膜上存在Sp激酶活性；在那里，高Sp抑制S1P刺激的膜催化的肌动蛋白组装。在巨噬细胞中，高S1P有利于杀死吞噬小体中的分枝杆菌，这是一种与肌动蛋白组装有关的促炎反应，而Sp则作为一种抗炎因子，有利于分枝杆菌的生长。最近研究表明，结核分枝杆菌等致病分支杆菌阻止其吞噬小体与溶酶体融合的能力依赖于它们抑制Sp激酶的能力。这里的目标是更详细地描述分离的吞噬小体和巨噬细胞中的吞噬小体上的Sp激酶。这些分析将通过使用GFP-Sp激酶结构和RNAi实验来选择性地移除Sp激酶及其相互连接的分子来促进。LBP肌动蛋白的组装依赖于Ezrin和P14，5P2，并受PLD调节。根据文献，Sp Kinase直接与PLD结合，而PLD本身既结合抑制其活性的Gactin，又结合刺激PLD的F-actin。SP激酶还间接结合PKA，而cAMP/PKA抑制吞噬小体肌动蛋白组装。这些相互作用并不都是在一个细胞系统中分析的。巨噬细胞内分离的LBP和吞噬小体是破译鞘脂在一个明确的膜过程中的作用的有吸引力的系统，肌动蛋白组装似乎是促炎反应的一部分。这与杀死致病分枝杆菌有关，调节鞘氨酸激酶活性可被认为是治疗这些病原体的方法。