Chlamydia exploits filopodial capture and a macropinocytosis-like pathway for host cell entry.
Chlamydia exploits filopodial capture and a macropinocytosis-like pathway for host cell entry.
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DOI：
10.1371/journal.ppat.1007051
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发表时间：
2018-05
期刊：
影响因子：
6.7
通讯作者：
Hayward RD
中科院分区：
文献类型：
--
作者：
Ford C;Nans A;Boucrot E;Hayward RD
病原体劫持宿主的内吞途径，迫使自己进入真核靶细胞。许多细菌利用受体介导的拉链或直接注射毒力蛋白来触发膜重组和细胞骨架重排。相比之下，胞外C.沙眼原体（EB）显然采用拉链和触发机制两者的小面，并且直径仅约400 nm。我们对C.沙眼衣原体的进入揭示了与入侵EB相关的出乎意料的多种宿主结构，表明内化可能通过多个潜在冗余途径或单个途径内的几个连续事件进行。在这里，我们进行了定量分析的肌动蛋白组织在衣原体入口灶，突出丝状伪足捕获和吞噬杯占主导地位的和保守的形态结构早期内化。我们应用基于通道的筛选和雇用报告系统地分析和可视化的时空贡献不同的内吞信号介质，以C。沙眼进入。除了Rac 1 GT3及其相关的成核促进因子（NPF）WAVE的公认作用外，我们的数据还揭示了另一种未被识别的途径，该途径具有巨胞饮作用的关键特征：i）阿米洛利敏感性，ii）液相摄取，iii）NPF N-WASP的募集和活性，以及iv）磷酸肌醇-3-磷酸（PI 3 P）物质的局部产生。考虑到它们在巨胞饮作用和对PI 3 P的亲和力中的中心作用，我们评估了SNX-PX-BAR家族蛋白的作用。引人注目的是，SNX 9特异性地和瞬时地富集在C.沙眼侵入灶SNX 9-/-细胞在EB进入中表现出20%的缺陷，当细胞在没有沉积诱导的EB粘附的情况下被感染时，该缺陷增强至60%，这与初始EB-宿主相互作用中的缺陷一致。相应地，C.沙眼衣原体EB在SNX 9-/-细胞中特异性减弱，暗示SNX 9是衣原体进入早期丝状伪足捕获的中心宿主介体。我们的研究结果确定了一个意想不到的复杂的信号基础细胞进入这一主要的人类病原体，并提出有趣的相似之处与病毒进入机制。沙眼衣原体仍然是全球性传播疾病的主要细菌病原体，并在发展中国家导致一种称为沙眼的失明，世界卫生组织认为这是一种被忽视的热带疾病。尽管有这种负担，我们对它如何在分子水平上引起疾病的了解相对较少。衣原体必须生活在人体细胞内才能生存，在这里我们研究了它如何进入细胞的机制，这对生命周期至关重要。我们研究了细菌如何利用细胞内的信号通路，通过重组底层细胞骨架使细胞膜变形，并确定了参与这一过程的新因素。我们的研究结果表明，一些病毒如何进入细胞具有有趣的相似性。更好地了解这些过程可能有助于开发未来的疫苗和新的治疗方法。
Pathogens hijack host endocytic pathways to force their own entry into eukaryotic target cells. Many bacteria either exploit receptor-mediated zippering or inject virulence proteins directly to trigger membrane reorganisation and cytoskeletal rearrangements. By contrast, extracellular C. trachomatis elementary bodies (EBs) apparently employ facets of both the zipper and trigger mechanisms and are only ~400 nm in diameter. Our cryo-electron tomography of C. trachomatis entry revealed an unexpectedly diverse array of host structures in association with invading EBs, suggesting internalisation may progress by multiple, potentially redundant routes or several sequential events within a single pathway. Here we performed quantitative analysis of actin organisation at chlamydial entry foci, highlighting filopodial capture and phagocytic cups as dominant and conserved morphological structures early during internalisation. We applied inhibitor-based screening and employed reporters to systematically assay and visualise the spatio-temporal contribution of diverse endocytic signalling mediators to C. trachomatis entry. In addition to the recognised roles of the Rac1 GTPase and its associated nucleation-promoting factor (NPF) WAVE, our data revealed an additional unrecognised pathway sharing key hallmarks of macropinocytosis: i) amiloride sensitivity, ii) fluid-phase uptake, iii) recruitment and activity of the NPF N-WASP, and iv) the localised generation of phosphoinositide-3-phosphate (PI3P) species. Given their central role in macropinocytosis and affinity for PI3P, we assessed the role of SNX-PX-BAR family proteins. Strikingly, SNX9 was specifically and transiently enriched at C. trachomatis entry foci. SNX9-/- cells exhibited a 20% defect in EB entry, which was enhanced to 60% when the cells were infected without sedimentation-induced EB adhesion, consistent with a defect in initial EB-host interaction. Correspondingly, filopodial capture of C. trachomatis EBs was specifically attenuated in SNX9-/- cells, implicating SNX9 as a central host mediator of filopodial capture early during chlamydial entry. Our findings identify an unanticipated complexity of signalling underpinning cell entry by this major human pathogen, and suggest intriguing parallels with viral entry mechanisms. Chlamydia trachomatis remains the leading bacterial agent of sexually transmitted disease worldwide and causes a form of blindness called trachoma in Developing nations, which is recognised by the World Health Organisation as a neglected tropical disease. Despite this burden, we know comparatively little about how it causes disease at a molecular level. Chlamydia must live inside human cells to survive, and here we study the mechanism of how it enters cells, which is critical to the lifecycle. We study how the bacterium exploits signalling pathways inside the cell to its own advantage to deform the cell membrane by reorganising the underlying cell skeleton, and identify new factors involved in this process. Our findings suggest intriguing similarities with how some viruses enter cells. A better understanding of these processes may help to develop future vaccines and new treatments.
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影响因子：
19
作者：
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通讯作者：
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影响因子：
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