Mycobacterium tuberculosis Type VII Secretion System Effectors Differentially Impact the ESCRT Endomembrane Damage Response.
Mycobacterium tuberculosis Type VII Secretion System Effectors Differentially Impact the ESCRT Endomembrane Damage Response.
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DOI：
10.1128/mbio.01765-18
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发表时间：
2018-11-27
期刊：
影响因子：
6.4
通讯作者：
Philips JA
中科院分区：
文献类型：
--
作者：
Mittal E;Skowyra ML;Uwase G;Tinaztepe E;Mehra A;Köster S;Hanson PI;Philips JA
结核分枝杆菌导致结核病，它比任何其他感染致死的人都多。结核分枝杆菌生长在巨噬细胞中，巨噬细胞专门吞噬和降解微生物。像许多细胞内病原体一样，为了引起疾病，结核分枝杆菌在巨噬细胞摄取后破坏其封闭的膜结合腔室（吞噬体）。最近的研究表明，当化学物质破坏这种类型的细胞内隔室时，细胞利用称为运输所需的内体分选复合体（ESCRT）的机制迅速检测并修复损伤。因此，我们假设ESCRT也可能对病原体诱导的损伤有反应。同时，我们之前的工作表明结核分枝杆菌的EsxG-EsxH异源二聚体可以抑制ESCRT，这增加了结核分枝杆菌损害这种宿主反应的可能性。在这里，我们发现ESCRT被招募到受损的结核分枝杆菌吞噬体中，EsxG-EsxH破坏ESCRT介导的膜修复。因此，我们的研究证明了宿主和病原体之间在膜完整性方面的斗争。细胞内病原体有不同的策略来突破内溶酶体屏障，以便它们可以将效应器传递到宿主细胞质中，获取营养物质，在细胞质中复制，并避免在溶酶体中降解。在结核分枝杆菌的情况下，细菌在被巨噬细胞吞噬后不久就穿孔吞噬体膜。吞噬体损伤取决于分枝杆菌ESX-1 VII型分泌系统（T7SS）。无菌损伤，如二氧化硅晶体或膜溶肽，也可以破坏吞噬体和内溶酶体膜。最近的研究表明，宿主内体转运所需分选复合体（ESCRT）机制对无菌内溶酶体损伤迅速作出反应并促进膜修复。我们假设escrt也可能对病原体诱导的吞噬体损伤作出反应，而结核分枝杆菌可能损害宿主的这种反应。事实上，我们发现ESCRT-III蛋白以esx -1依赖的方式被募集到结核分枝杆菌吞噬体中。我们之前已经证明，由ESX-3 T7SS分泌的分枝杆菌效应物EsxG/TB9.8和EsxH/TB10.4可以抑制escrt依赖性受体向溶酶体的运输。在此，我们还发现esrt - iii向内溶酶体损伤位点的募集被EsxG和EsxH拮抗，无论是在结核分枝杆菌感染还是无菌损伤的情况下。此外，EsxG和EsxH本身在几分钟内以独立于钙和ESCRT-III募集的方式对膜损伤作出反应。因此，我们的研究揭示了T7SS效应物和ESCRT参与了一系列控制吞噬体完整性的措施和对策。
Mycobacterium tuberculosis causes tuberculosis, which kills more people than any other infection. M. tuberculosis grows in macrophages, cells that specialize in engulfing and degrading microorganisms. Like many intracellular pathogens, in order to cause disease, M. tuberculosis damages the membrane-bound compartment (phagosome) in which it is enclosed after macrophage uptake. Recent work showed that when chemicals damage this type of intracellular compartment, cells rapidly detect and repair the damage, using machinery called the endosomal sorting complex required for transport (ESCRT). Therefore, we hypothesized that ESCRT might also respond to pathogen-induced damage. At the same time, our previous work showed that the EsxG-EsxH heterodimer of M. tuberculosis can inhibit ESCRT, raising the possibility that M. tuberculosis impairs this host response. Here, we show that ESCRT is recruited to damaged M. tuberculosis phagosomes and that EsxG-EsxH undermines ESCRT-mediated endomembrane repair. Thus, our studies demonstrate a battle between host and pathogen over endomembrane integrity. Intracellular pathogens have varied strategies to breach the endolysosomal barrier so that they can deliver effectors to the host cytosol, access nutrients, replicate in the cytoplasm, and avoid degradation in the lysosome. In the case of Mycobacterium tuberculosis, the bacterium perforates the phagosomal membrane shortly after being taken up by macrophages. Phagosomal damage depends upon the mycobacterial ESX-1 type VII secretion system (T7SS). Sterile insults, such as silica crystals or membranolytic peptides, can also disrupt phagosomal and endolysosomal membranes. Recent work revealed that the host endosomal sorting complex required for transport (ESCRT) machinery rapidly responds to sterile endolysosomal damage and promotes membrane repair. We hypothesized that ESCRTs might also respond to pathogen-induced phagosomal damage and that M. tuberculosis could impair this host response. Indeed, we found that ESCRT-III proteins were recruited to M. tuberculosis phagosomes in an ESX-1-dependent manner. We previously demonstrated that the mycobacterial effectors EsxG/TB9.8 and EsxH/TB10.4, both secreted by the ESX-3 T7SS, can inhibit ESCRT-dependent trafficking of receptors to the lysosome. Here, we additionally show that ESCRT-III recruitment to sites of endolysosomal damage is antagonized by EsxG and EsxH, both within the context of M. tuberculosis infection and sterile injury. Moreover, EsxG and EsxH themselves respond within minutes to membrane damage in a manner that is independent of calcium and ESCRT-III recruitment. Thus, our study reveals that T7SS effectors and ESCRT participate in a series of measures and countermeasures for control of phagosome integrity.