Rab14 is critical for maintenance of Mycobacterium tuberculosis phagosome maturation arrest
Rab14 is critical for maintenance of Mycobacterium tuberculosis phagosome maturation arrest
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DOI：
10.1038/sj.emboj.7601407
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发表时间：
2006-11-15
期刊：
影响因子：
11.4
通讯作者：
Deretic, Vojo
中科院分区：
文献类型：
--
作者：
Kyei, George B.;Vergne, Isabelle;Deretic, Vojo
结核分枝杆菌在感染的巨噬细胞中阻止吞噬体成熟，并且除了健康意义之外，还提供了一个极好的模型系统来解剖吞噬溶酶体生物合成途径。在这里，我们证明了一个关键的作用，小GTTRab 14在维持分枝杆菌吞噬体成熟阻滞。四维显微镜显示，吞噬后，含有活分枝杆菌的吞噬体积累Rab 14。Rab 14的募集具有很强的功能性后果，因为通过siRNA敲低内源性Rab 14或过量表达Rab 14显性阴性突变体（Rab 14 S25 N和Rab 14 N125 I）释放了成熟阻滞，并允许携带活分枝杆菌的吞噬体进入吞噬溶酶体。相反，野生型Rab 14和组成型活性突变体Rab 14 Q70 L的过度表达阻止了具有死亡分枝杆菌的吞噬体默认成熟为吞噬溶酶体细胞器。机制研究表明Rab 14在刺激吞噬体和早期内体之间的细胞器融合中发挥作用，但不与晚期内体融合。Rab 14使分枝杆菌吞噬体能够保持早期内体特征，并避免晚期内体/溶酶体降解组分。
Mycobacterium tuberculosis arrests phagosomal maturation in infected macrophage, and, apart from health significance, provides a superb model system to dissect the phagolysosomal biogenesis pathway. Here, we demonstrate a critical role for the small GTPase Rab14 in maintaining mycobacterial phagosome maturation block. Four-dimensional microscopy showed that phagosomes containing live mycobacteria accumulated Rab14 following phagocytosis. The recruitment of Rab14 had strong functional consequence, as a knockdown of endogenous Rab14 by siRNA or overexpression of Rab14 dominant-negative mutants (Rab14S25N and Rab14N125I) released the maturation block and allowed phagosomes harboring live mycobacteria to progress into phagolysosomes. Conversely, overexpression of the wild-type Rab14 and the constitutively active mutant Rab14Q70L prevented phagosomes with dead mycobacteria from undergoing default maturation into phagolysosomal organelles. Mechanistic studies demonstrated a role for Rab14 in stimulating organellar fusion between phagosomes and early endosomes but not with late endosomes. Rab14 enables mycobacterial phagosomes to maintain early endosomal characteristics and avoid late endosomal/lysosomal degradative components.