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Functional analyses of the type III effectors in pathogenic E.coli

致病性大肠杆菌 III 型效应子的功能分析

基本信息

批准号：
16590370
负责人：
ABE Akio
金额：
$ 2.24万
依托单位：
Kitasato University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16590370/
关键词：
Enteropathogenic E.coli Enterohemorrhagic E.coli Type III secretion system Diarrhea Effector Microtuble GEF-H1 Tight junction アクチン GFF-H1

项目摘要

Enteropathogenic Escherichia coli delivers a subset of effectors into host cells via a type III secretion system, and this step is required for the progression of disease. In this study, we demonstrated that the type III effectors, EspG and its homolog EspG2, trigger actin stress fiber formation and the destruction of the microtubule networks beneath adherent bacteria. Both effectors were shown to possess the ability to interact with tubulins, and to stimulate microtubule destabilization in vitro. A recent study showed that microtubule-bound GEF-H1, a RhoA-specific guanine nucleotide exchange factor, was converted to its active form by microtubule destabilization, and this sequence of events resulted in RhoA stimulation. Indeed, EspG- and EspG2-induced stress fiber formation was inhibited by the expression of dominant-negative forms of GEF-H1 and RhoA, but not of Rac1 and Cdc42. These results indicate that the impact of EspG/EspG2 on microtubule networks triggers the activation of the … More RhoA-ROCK signaling pathway via GEF-H1 activity. In addition, we revealed that the EspG/EspG2 alter epithelial paracellular permeability. When MDCK cells were infected with wild-type (WT) EPEC, RhoA was activated, and this event was dependent on the delivery of either EspG or EspG2 into host cells. In contrast, a loss of transepithelial electrical resistance and ZO-1 disruption were induced by infection with an espG/espG2 double-knockout mutant, as was the case with the WT EPEC, indicating that EspG/EspG2 is not involved in the disruption of tight junctions during EPEC infection. Although EspG- and EspG2-expressing MDCK cells exhibited normal overall morphology and maintained fully assembled tight junctions, the paracellular permeability to 4-kDa dextran, but not the paracellular permeability to 500-kDa dextran, was greatly increased. This report reveals for the first time that a pathogen can regulate the size-selective paracellular permeability of epithelial cells in order to elicit a disease process. Less

致病性大肠杆菌通过III型分泌系统将效应子的子集递送到宿主细胞中，并且这一步骤是疾病进展所必需的。在这项研究中，我们证明了III型效应子EspG及其同源物EspG 2触发肌动蛋白应力纤维的形成和粘附细菌下方微管网络的破坏。这两种效应器被证明具有与微管蛋白相互作用的能力，并在体外刺激微管不稳定。最近的一项研究表明，微管结合GEF-H1，RhoA特异性鸟嘌呤核苷酸交换因子，通过微管去稳定化转化为其活性形式，这一系列事件导致RhoA刺激。事实上，EspG和EspG 2诱导的应力纤维的形成被抑制的GEF-H1和RhoA的显性负性形式的表达，但不Rac 1和Cdc 42。这些结果表明，EspG/EspG 2对微管网络的影响触发了微管蛋白的激活。 ...更多信息 RhoA-ROCK信号通路通过GEF-H1活性。此外，我们发现EspG/EspG 2改变上皮细胞旁通透性。当用野生型（WT）EPEC感染MDCK细胞时，RhoA被激活，并且该事件依赖于EspG或EspG 2向宿主细胞中的递送。与此相反，损失的跨上皮电阻和ZO-1破坏诱导感染的espG/espG 2双敲除突变体，是与WT EPEC的情况下，表明EspG/EspG 2是不参与EPEC感染过程中的紧密连接的破坏。尽管表达EspG和EspG 2的MDCK细胞表现出正常的整体形态并保持完全组装的紧密连接，但对4-kDa葡聚糖的细胞旁渗透性，而不是对500-kDa葡聚糖的细胞旁渗透性，大大增加。这份报告首次揭示了病原体可以调节上皮细胞的大小选择性细胞旁通透性，以引发疾病过程。少