Extracellular signal-regulated kinase induces phosphorylation of IκBα in Helicobacter pylori-infected gastric epithelial AGS cells

In Helicobacter pylori (H. pylori)-induced gastric ulceration, NF-κB regulates the expression of inflammatory genes. NF-κB is activated by phsophorylation of its endogenous inhibitor, IκBα. The possible involvement of mitogenactivated protein kinase (MAPK) on NF-κB activation has been suggested in various cells. Present study aims to investigate whether H. pylori in a Korean isolate induces phosphorylation of IkBα and whether H. pylori-induced phosphorylation of IkBα is mediated by MAPK in gastric epithelial AGS cells. AGS cells were treated with MAPK inhibitors (U0126 for extracellular signal-regulated kinase, SB203580 for p38 kinase, SP600125 for c-Jun NH2-terminal protein kinases) and stimulated with H. pylori. As a result, H. pylori increased phospho-specific IκBα accompanied with the decrease in control IκBα. H. pylori-induced phosphorylation of IκBα was inhibited by treatment of U0126, but not by SB203580 or SP600125. In conclusion, extracellular signal-regulated kinase induces phosphorylation of IκBα in H. pylori-infected AGS cells.