Department of Bacteriology I, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan.
Department of Life Science and Medical Bioscience, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
Commun Biol. 2020 Jan 13;3(1):25. doi: 10.1038/s42003-020-0753-3.
In innate immunity, multiple autophagic processes eliminate intracellular pathogens, but it remains unclear whether noncanonical autophagy and xenophagy are coordinated, and whether they occur concomitantly or sequentially. Here, we show that Streptococcus pneumoniae, a causative of invasive pneumococcal disease, can trigger FIP200-, PI3P-, and ROS-independent pneumococcus-containing LC3-associated phagosome (LAPosome)-like vacuoles (PcLVs) in an early stage of infection, and that PcLVs are indispensable for subsequent formation of bactericidal pneumococcus-containing autophagic vacuoles (PcAVs). Specifically, we identified LC3- and NDP52-delocalized PcLV, which are intermediates between PcLV and PcAV. Atg14L, Beclin1, and FIP200 were responsible for delocalizing LC3 and NDP52 from PcLVs. Thus, multiple noncanonical and canonical autophagic processes are deployed sequentially against intracellular S. pneumoniae. The Atg16L1 WD domain, p62, NDP52, and poly-Ub contributed to PcLV formation. These findings reveal a previously unidentified hierarchical autophagy mechanism during bactericidal xenophagy against intracellular bacterial pathogens, and should improve our ability to control life-threating pneumococcal diseases.
在先天免疫中,多种自噬过程可以清除细胞内病原体,但目前尚不清楚非典型自噬和异噬是否协调,以及它们是同时发生还是相继发生。在这里,我们表明,导致侵袭性肺炎球菌病的肺炎链球菌可以在感染的早期触发 FIP200、PI3P 和 ROS 非依赖性含有肺炎球菌的 LC3 相关吞噬体(LAPosome)样空泡(PcLVs),并且 PcLVs 对于随后形成杀菌性含肺炎球菌的自噬空泡(PcAVs)是必不可少的。具体而言,我们鉴定了 LC3 和 NDP52 去定位的 PcLV,它是 PcLV 和 PcAV 之间的中间体。Atg14L、Beclin1 和 FIP200 负责将 LC3 和 NDP52 从 PcLVs 中去定位。因此,针对细胞内 S. pneumoniae ,多种非典型和典型的自噬过程被相继部署。Atg16L1 WD 结构域、p62、NDP52 和多聚泛素有助于 PcLV 的形成。这些发现揭示了针对细胞内细菌病原体的杀菌性异噬作用过程中以前未被识别的分层自噬机制,这应该提高我们控制危及生命的肺炎球菌病的能力。