Atg5-independent sequestration of ubiquitinated mycobacteria.
Atg5-independent sequestration of ubiquitinated mycobacteria.
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DOI：
10.1371/journal.ppat.1000430
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发表时间：
2009-05
期刊：
影响因子：
6.7
通讯作者：
Brown EJ
中科院分区：
文献类型：
--
作者：
Collins CA;De Mazière A;van Dijk S;Carlsson F;Klumperman J;Brown EJ
像其他几种细胞内病原体一样，海分枝杆菌（Mm）从吞噬体逃逸到宿主细胞质中，在那里它可以吞噬肌动蛋白，导致运动，促进扩散到邻近细胞。然而，只有约25%的内化Mm形成肌动蛋白尾巴，其余细菌的命运尚不清楚。在这里，我们表明，在一个新的和复杂的主机病原体相互作用的结果胞质访问：主机巨噬细胞泛素化毫米，而毫米脱落的泛素化细胞壁。吞噬体逃逸和泛素化的MM迅速发生，感染后3.5小时之前，在同一时间，泛素化的MM细胞壁材料与宿主衍生的致密膜网络混合出现在细胞溶质细菌附近，这表明细胞壁脱落和与残余的裂解吞噬体的关联。在感染后24小时，聚合肌动蛋白的Mm没有被泛素化，而泛素化的Mm在类似溶酶体的LAMP-1阳性空泡内被发现。虽然观察到双膜隔离Mm远离胞质溶胶，Mm的LAMP-1阳性空泡的靶向是独立于经典的自噬，如通过LC 3协会和Atg 5的情况下，其形成的独立性证明。此外，泛素化和LAMP-1协会没有发生突变体无毒Mm缺乏ESX-1（VII型）分泌，未能逃脱的主要吞噬体，除了其功能在吞噬体逃逸，ESX-1是不是直接需要Mm泛素化在巨噬细胞或体外。这些数据表明，有毒的Mm遵循两个不同的路径，在受感染的宿主细胞的胞质溶胶：细菌泛素化之后，通过自噬独立的途径螯合到溶酶体样细胞器，而细胞壁脱落可能允许逃脱这种命运，允许继续居住在胞质溶胶和形成肌动蛋白尾巴。 M.结核病是世界上最普遍的病原体之一，每年感染三分之一的人，造成200万人死亡。M. marinum（Mm）作为M.由于其相对安全性及其共同的发病机制，因此其在结核病中的作用是非常重要的;例如，先前的研究已经强调了分泌系统ESX-1在M.结核病和MM。在这里，我们表明，主机的泛素系统，最有名的标记宿主蛋白质的降解，也承认MM已经逃脱了他们原来的吞噬体通过ESX-1依赖的机制，并进入胞质溶胶。泛素化的细菌有两种不同的命运;泛素标记的Mm可以被隔离到溶酶体样区室中，但它们也可以脱落细胞壁，这可能使它们逃避隔离。溶酶体隔离独立于自噬，自噬是对饥饿或感染的反应，导致细胞器和某些其他胞内病原体的降解。这些实验揭示了泛素化作为宿主细胞识别分枝杆菌的机制，以及宿主和入侵微生物之间可能适合于治疗干预的新界面的存在。
Like several other intracellular pathogens, Mycobacterium marinum (Mm) escapes from phagosomes into the host cytosol where it can polymerize actin, leading to motility that promotes spread to neighboring cells. However, only ∼25% of internalized Mm form actin tails, and the fate of the remaining bacteria has been unknown. Here we show that cytosolic access results in a new and intricate host pathogen interaction: host macrophages ubiquitinate Mm, while Mm shed their ubiquitinated cell walls. Phagosomal escape and ubiquitination of Mm occured rapidly, prior to 3.5 hours post infection; at the same time, ubiquitinated Mm cell wall material mixed with host-derived dense membrane networks appeared in close proximity to cytosolic bacteria, suggesting cell wall shedding and association with remnants of the lysed phagosome. At 24 hours post-infection, Mm that polymerized actin were not ubiquitinated, whereas ubiquitinated Mm were found within LAMP-1–positive vacuoles resembling lysosomes. Though double membranes were observed which sequestered Mm away from the cytosol, targeting of Mm to the LAMP-1–positive vacuoles was independent of classical autophagy, as demonstrated by absence of LC3 association and by Atg5-independence of their formation. Further, ubiquitination and LAMP-1 association did not occur with mutant avirulent Mm lacking ESX-1 (type VII) secretion, which fail to escape the primary phagosome; apart from its function in phagosome escape, ESX-1 was not directly required for Mm ubiquitination in macrophages or in vitro. These data suggest that virulent Mm follow two distinct paths in the cytosol of infected host cells: bacterial ubiquitination is followed by sequestration into lysosome-like organelles via an autophagy-independent pathway, while cell wall shedding may allow escape from this fate to permit continued residence in the cytosol and formation of actin tails. M. tuberculosis is one of the world's most prevalent pathogens, infecting one third of humans and contributing to 2 million deaths each year. M. marinum (Mm) has been increasingly studied as a model of M. tuberculosis due to its relative safety and its shared mechanisms of pathogenesis; for example, previous studies have highlighted the importance of the secretion system ESX-1 in pathogenesis of both M. tuberculosis and Mm. Here, we show that the host's ubiquitin system, best known for tagging host proteins for degradation, also recognizes Mm that have escaped their original phagosomes via an ESX-1–dependent mechanism and entered into the cytosol. Ubiquitinated bacteria have two distinct fates; ubiquitin tagged Mm can be sequestered into lysosome-like compartments, but they also can shed cell wall, which may allow them to evade sequestration. Lysosomal sequestration is independent of autophagy, a response to starvation or infection that leads to degradation of organelles and certain other intracytosolic pathogens. These experiments reveal ubiquitination as a mechanism of host cell recognition of mycobacteria and the existence of a new interface between the host and invading microbe that may be amenable to therapeutic intervention.
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DOI：
10.1083/jcb.152.4.657
发表时间：
2001-02-19
期刊：
The Journal of cell biology
影响因子：
--
作者：
Mizushima N;Yamamoto A;Hatano M;Kobayashi Y;Kabeya Y;Suzuki K;Tokuhisa T;Ohsumi Y;Yoshimori T
通讯作者：
Yoshimori T
影响因子：
6.7
作者：
Angot, Aurelie;Vergunst, Annette;Genin, Stephane;Peeters, Nemo
通讯作者：
Peeters, Nemo
影响因子：
64.5
作者：
Katzmann, DJ;Babst, M;Emr, SD
通讯作者：
Emr, SD
影响因子：
3.4
作者：
Koo, Ingrid C.;Wang, Chen;Brown, Eric J.
通讯作者：
Brown, Eric J.
p62/SQSTM1形成自噬降解的蛋白质聚集体，并对亨廷顿蛋白诱导的细胞死亡具有保护作用。
影响因子：
7.8
作者：
Bjorkoy, Geir;Lamark, Trond;Brech, Andreas;Outzen, Heidi;Perander, Maria;Overvatn, Aud;Stenmark, Harald;Johansen, Terje
通讯作者：
Johansen, Terje