Rab5a GTPase regulates fusion between pathogen-containing phagosomes and cytoplasmic organelles in human neutrophils.
Rab5a GTPase regulates fusion between pathogen-containing phagosomes and cytoplasmic organelles in human neutrophils.
复制标题
Rab5a GTPase 调节人中性粒细胞中含有病原体的吞噬体与细胞质细胞器之间的融合。
作者：
N. Perskvist;K. Roberg;A. Kulyté;O. Stendahl
吞噬溶酶体的生物发生通过与内吞细胞器的一系列连续的相互作用进行，该过程已知由Rab和SNARE蛋白调节。然而，嗜中性粒细胞吞噬体成熟的分子机制尚不清楚。我们研究了含有细胞内病原体结核分枝杆菌与细胞外病原体金黄色葡萄球菌的吞噬体之间的融合（将含有分枝杆菌的吞噬体命名为MCP，将S.含金黄色吞噬体）和人嗜中性粒细胞的细胞质区室。蛋白质印迹分析后分离的吞噬体内化显示，乳铁蛋白（次级颗粒的成分）和LAMP-1被纳入SCP和MCP，而hck（嗜天青颗粒的标志物）仅与SCP相互作用。Rab 5a蛋白和突触融合蛋白-4的亚细胞分布表明在中性粒细胞中颗粒和/或内体与靶膜的对接中起作用。我们观察到，在吞噬过程中，Rab 5a在GTP结合的形式与MCP膜上的突触融合蛋白-4相互作用，并保留长达90分钟，而复合物在5分钟内被招募到SCP，但在吞噬30分钟后选择性地从这些空泡中耗尽。通过反义寡核苷酸下调Rab 5a有效地减少Rab 5a的合成，突触融合蛋白-4与MCP和SCP的结合以及由含病原体的吞噬体所表现出的融合能力，但对细菌内化没有影响。这些数据表明，颗粒融合的差异与Rab 5a和突触融合蛋白-4与吞噬体的关联的差异相关。细胞内含有病原体的吞噬体保留Rab 5a和突触融合蛋白-4，而细胞外含有病原体的吞噬体与该复合物短暂结合。这些结果还确定Rab 5a作为人嗜中性粒细胞吞噬溶酶体成熟的关键调节因子。
Biogenesis of phagolysosomes proceeds through a sequential series of interactions with endocytic organelles, a process known to be regulated by Rab and SNARE proteins. The molecular mechanisms underlying phagosome maturation in neutrophils are, however, not clearly understood. We investigated fusion between phagosomes containing the intracellular pathogen Mycobacterium tuberculosis versus the extracellular pathogen Staphylococcus aureus (designated MCP for mycobacteria-containing phagosome and SCP for S. aureus-containing phagosome) and cytoplasmic compartments in human neutrophils. Western blot analysis of phagosomes isolated after internalisation revealed that lactoferrin (a constituent of secondary granules) and LAMP-1 were incorporated into both SCP and MCP, whereas hck (marker of azurophil granules) interacted solely with SCP. The subcellular distribution of the proteins Rab5a and syntaxin-4 suggested a role in docking of granules and/or endosomes to the target membrane in the neutrophil. We observed that during phagocytosis, Rab5a in GTP-bound form interacted with syntaxin-4 on the membrane of MCP and were retained for up to 90 minutes, whereas the complex was recruited to the SCP within 5 minutes but was selectively depleted from these vacuoles after 30 minutes of phagocytosis. Downregulation of Rab5a by antisense oligonucleotides efficiently reduced the synthesis of Rab5a, the binding of syntaxin-4 to MCP and SCP and the capacity for fusion exhibited by the pathogen-containing phagosomes, but it had no effect on bacteria internalisation. These data indicate that the difference in granule fusion is correlated with a difference in the association of Rab5a and syntaxin-4 with the phagosomes. Intracellular pathogen-containing phagosomes retain Rab5a and syntaxin-4, whereas extracellular pathogen-containing phagosomes bind briefly to this complex. These results also identified Rab5a as a key regulator of phagolysosome maturation in human neutrophils.
影响因子：
56.9
作者：
STURGILLKOSZYCKI, S;SCHLESINGER, PH;RUSSELL, DG
通讯作者：
RUSSELL, DG