The Helicobacter pylori CagA protein disrupts matrix adhesion of gastric epithelial cells by dephosphorylation of vinculin

Abstract

SummaryHelicobacter pylori colonizes the human stomach, contributing to or causing several diseases. Translocation of the CagA bacterial protein into gastric epithelial cells has been linked to an increased risk of peptic ulcer disease and gastric carcinoma. Upon translocation, CagA is tyrosine phosphorylated by Src family kinases (SFKs), which themselves become inactivated via a negative feedback loop. Here, we show that tyrosine-phosphorylated CagA disrupts adhesion of AGS cells to the extracellular matrix. Owing to the inactivation of c-Src via CagA interaction, vinculin is dephosphorylated at tyrosine residues, 100 and 1065, by corresponding phosphatases. Vinculin dephosphorylation disturbs the interaction and recruitment of the actin-related protein 2/3 (Arp2/3) complex by p34Arc, resulting in a reduction of focal adhesion complexes. These defects can be mimicked by downregulating vinculin using RNA interference in non-infected cells. Tyrosine dephosphorylation of vinculin results in severe cellular deficiencies in cell-matrix adhesion, cell spreading and wound repair. We hypothesize that CagA-mediated inactivation of vinculin is a key step in the mechanism by which H. pylori induces damage to the gastric epithelium and represents an important step in disease development.

Structural insights into Helicobacter pylori oncoprotein CagA interaction with β1 integrin

“…A remarkable and key property of CagA is that it can modify several types of cell-to cell junctions (22). In particular, CagA colocalizes with and affects FAK and vinculin phosphorylation at FAs (7,23,24). CagA also disrupts the E-cadherin/β-catenin complex at adherens junctions (8,9).…”

Evaluation of Cell- Morphological Changes by Helicobacter pylori CagA and Pragmin in AGS Human Gastric Carcinoma Cells

“…In this regard, it was reported that Src-mediated CagA phosphorylation is followed by a rapid inactivation of Src kinase activity by the binding of CagA to Csk, and then, Src kinase inactivation leads to the dephosphorylation of Src target proteins such as vinculin, ezrin, and cortactin, which are important in the process of regulation of the actin cytoskeleton and focal adhesions. This process contributes to inducing morphological changes of H. pylori-infected cells (18,23,24). Also, it was shown that phosphorylation of cortactin (serine 405) was mediated by ERK1/2 kinases, which might trap activated FAK, leading to a disturbed turnover of focal adhesions and cell elongation morphology (25).…”

Vinculin phosphorylation at residues Y100 and Y1065 is required for cellular force transmission

“…Phosphorylation at position 822 by the kinase Abl is only required for E-cadherin-mediated force transmission and signaling in cell-cell contacts (Subauste et al, 2004), but not for force transmission through cell-ECM adhesions (Bays et al, 2014). By contrast, phosphorylation of vinculin at position 100 and 1065 by Src kinase affects cell spreading and wound repair (Zhang et al, 2004;Moese et al, 2007). Phosphorylation at position 1065 is also associated with the lipid membrane interaction of the vinculin tail domain (Ito et al, 1983;Chandrasekar et al, 2005) and generation of cellular tractions (Diez et al, 2009;Küpper et al, 2010).…”