Serine Phosphorylation of Cortactin Controls Focal Adhesion Kinase Activity and Cell Scattering Induced by Helicobacter pylori

Abstract

Cell migration and invasion require the coordinated regulation of cytoskeletal architectural changes by signaling factors, including the actin-binding protein cortactin. Bacterial and viral pathogens subvert these signaling factors to promote their uptake, spread and dissemination. We show that the gastric pathogen Helicobacter pylori (Hp) targets cortactin by two independent processes leading to its tyrosine dephosphorylation and serine phosphorylation to regulate cell scattering and elongation. The phosphorylation status of cortactin dictates its subcellular localization and signaling partners. Upon infection, cortactin was found to interact with and stimulate the kinase activity of focal adhesion kinase (FAK). This interaction required the SH3 domain and phosphorylation of cortactin at serine 405 and a proline-rich sequence in FAK. Using Hp as a model, this study unravels a previously unrecognized FAK activation pathway. We propose that Hp targets cortactin to protect the gastric epithelium from excessive cell lifting and ensure sustained infection in the stomach.

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

“…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). In another study, the activation of SHP-2 phosphatase activity was reported to inactivate FAK (focal adhesion kinase) in cells that ectopically express CagA (26).…”

c-Src and c-Abl kinases control hierarchic phosphorylation and function of the CagA effector protein in Western and East Asian Helicobacter pylori strains

“…To determine the minimum number of phosphorylated EPIYA motifs needed for phenotypic outcome during infection, we generated phosphorylation-mimetic strain 26695 CagA mutants with EPIYA tyrosines replaced by aspartic acid (Y>D), which serves as a phosphorylation substrate in other proteins (38,39). To avoid additional phosphorylation of the constructs by c-Src or c-Abl, all nontargeted tyrosines in adjacent EPIYA motifs were replaced by phenylalanines.…”

Extracellular secretion of protease HtrA fromCampylobacter jejuniis highly efficient and independent of its protease activity and flagellum

“…Horseradish peroxidase-conjugated anti-rabbit polyvalent sheep immunoglobulin was used as secondary antibody (DAKO Denmark A/S, DK-2600 Glostrup, Denmark). Blots were developed with ECL Plus Western blot reagents (GE Healthcare, UK limited Amersham Place, UK) as described [50].…”