The type three secretion system effector protein IpgB1 promotes Shigella flexneri cell-to-cell spread through double-membrane vacuole escape.
The type three secretion system effector protein IpgB1 promotes Shigella flexneri cell-to-cell spread through double-membrane vacuole escape.
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DOI：
10.1371/journal.ppat.1010380
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发表时间：
2022-03
期刊：
影响因子：
6.7
通讯作者：
Agaisse HF
中科院分区：
文献类型：
--
作者：
Weddle EA;Köseoğlu VK;DeVasure BA;Agaisse HF
福氏志贺氏菌是引起细菌性痢疾的重要人类病原体。在感染过程中，福氏志贺氏菌侵入结肠上皮细胞，劫持宿主细胞的细胞骨架在感染细胞的胞浆中移动，并通过形成膜突起在细胞之间传播，膜突起伸入相邻细胞并分解成双膜空泡(DMV)。福氏志贺氏菌在细胞间的传播需要三型细菌分泌系统(T3SS)的完整性。然而，T3SS效应蛋白在传播过程中的确切作用仍然知之甚少。在这里，我们研究了T3SS效应蛋白IpgB1在福氏志贺氏菌传播中的作用。IpgB1以前被认为是一种鸟嘌呤核苷酸交换因子，有助于侵袭。除了侵袭缺陷外，我们还发现ipgB1突变体在HT-29细胞中形成了较小的感染灶。这种表型的互补需要IpgB1的全球环境基金活性。使用实时共聚焦显微镜，我们表明ipgB1突变体在DMV逃逸中受到特异性损伤。在入侵过程中，IpgB1的宿主细胞靶标rac1的耗尽，以及对rac1信号的药理抑制，减少了细胞间的传播和DMV的逃逸。在靶向siRNA筛选中，我们发现RhoA耗尽恢复了ipgB1细胞间的扩散和DMV逃逸，揭示了IpgB1-rac1轴在拮抗RhoA介导的DMV逃逸限制中的关键作用。利用志贺氏菌病的幼兔模型，我们发现ipgB1突变体在感染动物的结肠中形成了更少和更小的感染灶，这与疾病症状的减轻有关，包括上皮开窗和血性腹泻。我们的结果表明，除了在侵袭过程中发挥作用外，IpgB1还调节Rho家族的小GTP酶信号，以促进细胞间传播、DMV逃逸和福氏志贺菌的致病。细菌性痢疾由福氏志贺氏菌引起，是一种严重的腹泻疾病，每年在全球范围内导致2亿多例病例和20多万人死亡。越来越多的福氏志贺菌菌株对多种抗生素产生抗药性，这一现象令人担忧，这使得人们迫切需要进一步了解福氏志贺菌是如何致病的。福氏志贺氏菌在人类结肠细胞内感染和复制，并在整个结肠传播，导致大量组织破坏和血性腹泻。人们对支持这一传播过程的机制知之甚少。在这里，我们描述了一种细菌蛋白IpgB1，它允许福氏志贺氏菌在整个人类(宿主)结肠中传播。当细菌从一个宿主细胞传播到另一个宿主细胞时，细菌被困在宿主细胞膜隔间，称为双膜空泡(DMV)。我们发现，IpgB1操纵宿主细胞信号蛋白来逃避DMV，传播到整个结肠，并导致疾病。我们的工作提供了对福氏志贺氏菌致病机制的洞察，并提出了新的治疗靶点。
S. flexneri is an important human pathogen that causes bacillary dysentery. During infection, S. flexneri invades colonic epithelial cells, hijacks the host cell cytoskeleton to move in the cytosol of infected cells, and spreads from cell to cell through formation of membrane protrusions that project into adjacent cells and resolve into double membrane vacuoles (DMVs). S. flexneri cell-to-cell spread requires the integrity of the bacterial type three secretion system (T3SS). However, the exact role of the T3SS effector proteins in the dissemination process remains poorly understood. Here, we investigated the role of the T3SS effector protein IpgB1 in S. flexneri dissemination. IpgB1 was previously characterized as a guanine nucleotide exchange factor (GEF) that contributes to invasion. In addition to the invasion defect, we showed that the ipgB1 mutant formed smaller infection foci in HT-29 cells. Complementation of this phenotype required the GEF activity of IpgB1. Using live confocal microscopy, we showed that the ipgB1 mutant is specifically impaired in DMV escape. Depletion of Rac1, the host cell target of IpgB1 during invasion, as well as pharmacological inhibition of Rac1 signaling, reduced cell-to-cell spread and DMV escape. In a targeted siRNA screen, we uncovered that RhoA depletion restored ipgB1 cell-to-cell spread and DMV escape, revealing a critical role for the IpgB1-Rac1 axis in antagonizing RhoA-mediated restriction of DMV escape. Using an infant rabbit model of shigellosis, we showed that the ipgB1 mutant formed fewer and smaller infection foci in the colon of infected animals, which correlated with attenuated symptoms of disease, including epithelial fenestration and bloody diarrhea. Our results demonstrate that, in addition to its role during invasion, IpgB1 modulates Rho family small GTPase signaling to promote cell-to-cell spread, DMV escape, and S. flexneri pathogenesis. Bacillary dysentery, caused by the bacterium Shigella flexneri, is a severe diarrheal disease that causes more than 200 million cases and over 200,000 deaths worldwide each year. The increasing and alarming presence of S. flexneri strains resistant to multiple antibiotics generates urgency for increased understanding of how S. flexneri causes disease. S. flexneri infects and replicates within human colon cells and spreads throughout the colon, leading to massive tissue destruction and bloody diarrhea. The mechanisms supporting this dissemination process are poorly understood. Here, we characterized one of the bacterial proteins, IpgB1, which allows S. flexneri to spread throughout the human (host) colon. Upon spreading from one host cell to another, the bacteria are entrapped in host cell membrane compartments termed double membrane vacuoles (DMVs). We found that IpgB1 manipulates host cell signaling proteins to escape DMVs, spread throughout the colon, and cause disease. Our work provides insight into the mechanisms by which S. flexneri causes disease and suggests novel therapeutic targets.
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影响因子：
64.8
作者：
通讯作者：
--
影响因子：
5.7
作者：
Agaisse H
通讯作者：
Agaisse H
DOI：
10.1083/jcb.201604015
发表时间：
2016-11-21
期刊：
The Journal of cell biology
影响因子：
--
作者：
Martin E;Ouellette MH;Jenna S
通讯作者：
Jenna S
影响因子：
5.8
作者：
Hachani, Abderrahman;Biskri, Latefa;Allaoui, Abdelmounaaim
通讯作者：
Allaoui, Abdelmounaaim
影响因子：
5.4
作者：
Anand I;Choi W;Isberg RR
通讯作者：
Isberg RR