Sphingomyelin functions as a novel receptor for Helicobacter pylori VacA.
Sphingomyelin functions as a novel receptor for Helicobacter pylori VacA.
复制标题
鞘磷脂充当幽门螺杆菌VACA的新型受体。
DOI：
10.1371/journal.ppat.1000073
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发表时间：
2008-05-23
期刊：
影响因子：
6.7
通讯作者：
Blanke, Steven R.
中科院分区：
文献类型：
--
作者：
Gupta, Vijay R.;Patel, Hetal K.;Kostolansky, Sean S.;Ballivian, Roberto A.;Eichberg, Joseph;Blanke, Steven R.
胃病原体幽门螺杆菌的空泡细胞毒素（VacA）结合并进入上皮细胞，最终导致细胞空泡化。据报道，几种宿主因子对VacA功能很重要，但这些因子均未被证明是毒素与质膜结合所必需的。因此，对毒素结合和功能都至关重要的细胞表面受体的身份仍然难以捉摸。在这里，我们确定VacA作为第一个细菌毒力因子，利用重要的质膜鞘磷脂，鞘磷脂（SM），作为细胞受体。用鞘磷脂酶耗尽质膜SM抑制VacA介导的空泡化，并显著降低HeLa细胞以及其他几种细胞系对VacA的敏感性。进一步的分析表明，SM是关键的VacA与质膜的相互作用。恢复质膜SM细胞先前耗尽SM是足以拯救毒素空泡化活性和质膜结合。VacA协会与洗涤剂耐膜抑制在细胞预处理SMase C，表明SM的重要性，VacA协会与脂筏微结构域。最后，VacA结合SM在体外ELISA测定的方式竞争性抑制的细胞溶素，一种已知的SM结合蛋白。我们的研究结果表明，VacA可以利用SM的能力，优先分配到脂筏，以访问筏相关的细胞机器先前显示毒素进入宿主细胞所需的模型。对病原菌产生的毒素的敏感性在很大程度上取决于宿主细胞质膜上毒素受体的存在与否。VacA是由致病性细菌幽门螺杆菌产生的一种重要毒素，它感染人体胃并引起胃溃疡疾病和胃癌。VacA结合并进入人体细胞，并诱导几种变化，最终导致中毒细胞的死亡。然而，负责毒素结合和功能的VacA受体的身份仍然是一个争论的话题。在本文中，我们证明了鞘磷脂，细胞表面的脂质具有重要的膜结构和信号传导特性，作为VacA受体的功能。我们证明，VacA结合鞘磷脂，鞘磷脂的存在或不存在的质膜上决定了多少VacA结合到细胞表面，因此，如何敏感的细胞毒素。鞘磷脂的鉴定还为VacA如何通过细胞表面的专门功能结构域进入细胞提供了概念框架。这是利用鞘磷脂作为受体的细菌毒素的第一个例子，未来的工作将集中在开发阻断VacA与鞘磷脂相互作用的策略上，从而保护细胞免受毒素作用的下游后果。
The vacuolating cytotoxin (VacA) of the gastric pathogen Helicobacter pylori binds and enters epithelial cells, ultimately resulting in cellular vacuolation. Several host factors have been reported to be important for VacA function, but none of these have been demonstrated to be essential for toxin binding to the plasma membrane. Thus, the identity of cell surface receptors critical for both toxin binding and function has remained elusive. Here, we identify VacA as the first bacterial virulence factor that exploits the important plasma membrane sphingolipid, sphingomyelin (SM), as a cellular receptor. Depletion of plasma membrane SM with sphingomyelinase inhibited VacA-mediated vacuolation and significantly reduced the sensitivity of HeLa cells, as well as several other cell lines, to VacA. Further analysis revealed that SM is critical for VacA interactions with the plasma membrane. Restoring plasma membrane SM in cells previously depleted of SM was sufficient to rescue both toxin vacuolation activity and plasma membrane binding. VacA association with detergent-resistant membranes was inhibited in cells pretreated with SMase C, indicating the importance of SM for VacA association with lipid raft microdomains. Finally, VacA bound to SM in an in vitro ELISA assay in a manner competitively inhibited by lysenin, a known SM-binding protein. Our results suggest a model where VacA may exploit the capacity of SM to preferentially partition into lipid rafts in order to access the raft-associated cellular machinery previously shown to be required for toxin entry into host cells. Sensitivity to toxins produced by pathogenic bacteria is largely dictated by the presence or absence of toxin receptors on the plasma membrane of host cells. VacA is an important toxin produced by the pathogenic bacterium Helicobacter pylori, which infects the human stomach and causes gastric ulcer disease and stomach cancer. VacA binds and enters human cells, and induces several changes resulting ultimately in the death of the intoxicated cells. However, the identity of the VacA receptor responsible for toxin binding and function has remained a topic of debate. In this paper, we demonstrate that sphingomyelin, a lipid on the surface of cells with important membrane structural and signaling properties, functions as a VacA receptor. We demonstrate that VacA binds to sphingomyelin, and that presence or absence of sphingomyelin on the plasma membrane dictates how much VacA binds to the cell surface, and therefore, how sensitive cells are to the toxin. The identification of sphingomyelin also provides a conceptual framework for how VacA may enter cells through specialized functional domains on the surface of cells. This is the first example of a bacterial toxin that exploits sphingomyelin as a receptor, and future work will focus on developing strategies to block VacA interactions with sphingomyelin, thereby protecting cells from the downstream consequences of toxin action.
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影响因子：
3.1
作者：
COVER, TL;PURYEAR, W;BLASER, MJ
通讯作者：
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影响因子：
30.8
作者：
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影响因子：
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作者：
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DOI：
10.1083/jcb.200609061
发表时间：
2007-04-23
期刊：
The Journal of cell biology
影响因子：
--
作者：
Gauthier NC;Monzo P;Gonzalez T;Doye A;Oldani A;Gounon P;Ricci V;Cormont M;Boquet P
通讯作者：
Boquet P
影响因子：
2.9
作者：
Chan, EC;Chang, CC;Wu, TZ
通讯作者：
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