Oliveira Maria Jose, Costa Angela Margarida, Costa Ana Catarina, Ferreira Rui Manuel, Sampaio Paula, Machado Jose Carlos, Seruca Raquel, Mareel Marc, Figueiredo Ceu
Institute of Molecular Pathology and Immunology, University of Porto, Porto, Portugal.
J Infect Dis. 2009 Sep 1;200(5):745-55. doi: 10.1086/604727.
Helicobacter pylori induces an invasive phenotype in gastric epithelial cells through a mechanism that requires the type IV secretion system and the phosphorylation of c-Met. The E-cadherin-catenin complex is a major component of the adherens junctions and functions as an invasion suppressor. We investigated whether E-cadherin has a role in H. pylori-induced, c-Met phosphorylation-dependent cell-invasive phenotype.
AGS cells that lack E-cadherin and that are invasive to H. pylori stimulation were transduced with E-cadherin and infected with H. pylori. NCI-N87 cells, which endogenously express E-cadherin, were also used for infection experiments.
E-cadherin was sufficient to suppress not only H. pylori-mediated cell-invasive phenotype but also c-Met and p120-catenin tyrosine phosphorylation. H. pylori infection led to increased interactions between E-cadherin and p120-catenin, c-Met and E-cadherin, and c-Met and p120-catenin. Using in vitro infection assays, we showed that H. pylori CagA interacts with E-cadherin, p120-catenin, and c-Met. Finally, using small interfering RNA, we showed that interactions between CagA and E-cadherin and between CagA and p120-catenin were established through c-Met.
We suggest that H. pylori alters the E-cadherin-catenin complex, leading to formation of a multiproteic complex composed of CagA, c-Met, E-cadherin, and p120-catenin. This complex abrogates c-Met and p120-catenin tyrosine phosphorylation and suppresses the cell-invasive phenotype induced by H. pylori.
幽门螺杆菌通过一种需要IV型分泌系统和c-Met磷酸化的机制诱导胃上皮细胞出现侵袭性表型。E-钙黏蛋白-连环蛋白复合体是黏着连接的主要成分，起侵袭抑制因子的作用。我们研究了E-钙黏蛋白在幽门螺杆菌诱导的、c-Met磷酸化依赖性细胞侵袭性表型中是否发挥作用。
用E-钙黏蛋白转导缺乏E-钙黏蛋白且对幽门螺杆菌刺激有侵袭性的AGS细胞，并感染幽门螺杆菌。内源性表达E-钙黏蛋白的NCI-N87细胞也用于感染实验。
E-钙黏蛋白不仅足以抑制幽门螺杆菌介导的细胞侵袭性表型，还能抑制c-Met和p120-连环蛋白的酪氨酸磷酸化。幽门螺杆菌感染导致E-钙黏蛋白与p120-连环蛋白、c-Met与E-钙黏蛋白以及c-Met与p120-连环蛋白之间的相互作用增加。通过体外感染试验，我们发现幽门螺杆菌CagA与E-钙黏蛋白、p120-连环蛋白和c-Met相互作用。最后，使用小干扰RNA，我们发现CagA与E-钙黏蛋白之间以及CagA与p120-连环蛋白之间的相互作用是通过c-Met建立的。
我们认为幽门螺杆菌改变了E-钙黏蛋白-连环蛋白复合体，导致形成由CagA、c-Met、E-钙黏蛋白和p120-连环蛋白组成的多蛋白复合体。该复合体消除了c-Met和p120-连环蛋白的酪氨酸磷酸化，并抑制了幽门螺杆菌诱导的细胞侵袭性表型。
