Li Qiurong, Zhang Qiang, Wang Chenyang, Li Ning, Li Jieshou
Institute of General Surgery, Jinling Hospital, Nanjing, China.
FEBS J. 2008 Dec;275(23):6022-32. doi: 10.1111/j.1742-4658.2008.06731.x.
Enteropathogenic Escherichia coli (EPEC) has been shown to disrupt the barrier function of host intestinal epithelial tissues through entering tight junctions. However, the mechanism by which this occurs remains poorly understood. In this study, we determined that EPEC invades host cells through tight junctions as it initiates infection. Immunofluorescence microscopy revealed redistribution of the tight-junction proteins occludin and ZO-1 from an intercellular to a cytoplasmic location after EPEC invasion. Flotillin-1 was recruited to sites of EPEC entry. EPEC entered host cells through tight-junction membrane microdomains. Tight-junction ultrastructure was disrupted following EPEC infection, accompanied by loss of barrier function. EPEC infection caused a time-dependent decrease in trans-epithelial electrical resistance. Subcellular fractionation using discontinuous sucrose density gradients demonstrated a decline in raft-associated occludin following exposure to EPEC. These results indicate the important role of host membrane tight-junction microdomains in EPEC invasion.
肠致病性大肠杆菌（EPEC）已被证明可通过进入紧密连接来破坏宿主肠道上皮组织的屏障功能。然而，其发生机制仍知之甚少。在本研究中，我们确定EPEC在引发感染时通过紧密连接侵入宿主细胞。免疫荧光显微镜检查显示，EPEC入侵后，紧密连接蛋白闭合蛋白和闭锁小带蛋白1（ZO-1）从细胞间位置重新分布到细胞质位置。小窝蛋白-1（Flotillin-1）被募集到EPEC进入的部位。EPEC通过紧密连接膜微结构域进入宿主细胞。EPEC感染后紧密连接超微结构被破坏，同时屏障功能丧失。EPEC感染导致跨上皮电阻随时间下降。使用不连续蔗糖密度梯度进行亚细胞分级分离显示，暴露于EPEC后，与脂筏相关的闭合蛋白减少。这些结果表明宿主膜紧密连接微结构域在EPEC入侵中起重要作用。
