Autophagy-mediated reentry of Francisella tularensis into the endocytic compartment after cytoplasmic replication
Autophagy-mediated reentry of Francisella tularensis into the endocytic compartment after cytoplasmic replication
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DOI：
10.1073/pnas.0601838103
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发表时间：
2006-09-26
影响因子：
11.1
通讯作者：
Celli, Jean
中科院分区：
文献类型：
--
作者：
Checroun, Claire;Wehrly, Tara D.;Celli, Jean
细胞内细菌病原体通过物理逃离其吞噬体并复制到细胞质中或通过调节吞噬体成熟和膜结合复制细胞器的生物发生来逃避哺乳动物细胞的杀菌功能。在这里，我们详细介绍了小鼠原代巨噬细胞的细胞内生命周期的土拉热弗朗西丝菌，一种高度感染性的细菌，生存和复制的哺乳动物细胞内。在与内吞途径的短暂相互作用后，细菌在感染后1小时从其吞噬体中逃逸，并在感染后4至20小时在细胞质中进行复制。出乎意料的是，随后发现大多数细菌被封闭在大的、无核的、LAMP-1阳性的空泡内，称为含有弗朗西斯菌的空泡（FCV）。FCV的形成需要细菌的胞质内复制。使用电子显微镜和荧光显微镜，我们观察到FCVs包含形态完整的细菌，尽管与溶酶体融合。FCV是多膜结构，其积累单丹酰尸胺并在其膜上展示自噬特异性蛋白LC 3。FCV的形成被3-甲基腺嘌呤显著抑制，证实了自噬途径在这些细胞器的生物发生中的作用。综上所述，我们的结果表明，通过自噬，F。土拉菌在胞质复制后重新进入内吞途径，这是迄今为止胞内病原体未描述的过程。
Intracellular bacterial pathogens evade the bactericidal functions of mammalian cells by physical escape from their phagosome and replication into the cytoplasm or through the modulation of phagosome maturation and biogenesis of a membrane-bound replicative organelle. Here, we detail in murine primary macrophages the intracellular life cycle of Francisella tularensis, a highly infectious bacterium that survives and replicates within mammalian cells. After transient interactions with the endocytic pathway, bacteria escaped from their phagosome by 1 h after infection and underwent replication in the cytoplasm from 4 to 20 h after infection. Unexpectedly, the majority of bacteria were subsequently found to be enclosed within large, juxtanuclear, LAMP-1-positive vacuoles called Franciselia-containing vacuoles (FCVs). FCV formation required intracytoplasmic replication of bacteria. Using electron and fluorescence microscopy, we observed that the FCVs contained morphologically intact bacteria, despite fusing with lysosomes. FCVs are multimembranous structures that accumulate monodansylcadaverine and display the autophagy-specific protein LC3 on their membrane. Formation of FCVs was significantly inhibited by 3-methyladenine, confirming a role for the autophagic pathway in the biogenesis of these organelles. Taken together, our results demonstrate that, via autophagy, F. tularensis reenters the endocytic pathway after cytoplasmic replication, a process thus far undescribed for intracellular pathogens.