Involvement of the epidermal growth factor receptor in the invasion of cultured mammalian cells by Salmonella typhimurium

Abstract

SALMONELLA infection continues to be a major world-wide health problem¹. One essential pathogenic feature common to all Salmonella is their ability to penetrate the cells of the intestinal epithelium which are normally non-phagocytic². The internalization of Salmonella into mammalian cells is thought to be a receptor-mediated phenomenon and the invasion of cultured epithelial cells depends on several Salmonella genes, but nothing is known about the host determinants participating in this interaction^3–6. Protein tyrosine phosphorylation follows stimulation of many cell-surface receptors to initiate signal transduction path-ways that stimulate cellular responses⁷. We report here that invasion of cultured Henle-407 cells by Salmonella typhimurium induces the tyrosine phosphorylation of the epidermal growth factor (EGF) receptor. In contrast, an isogenic strain of S. typhimurium that is defective in invasion owing to a mutation in the invA gene is unable to induce such phosphorylation. Addition of EGF to cultured Henle-407 cells allowed the internalization of the invasion-defective S. typhimurium invA mutant although it did not cause the internalization of an adherent, but non-invasive, strain of Escherichia coli. This result indicates that stimulation of the EGF receptor is involved in the invasion of cultured Henle-407 cells by S. typhimurium.