Role of enteroaggregative E.coli induced activation of epidermal growth factor receptor in cultured human intestinal epithelial cell lines

Abstract

Enteric pathogens exploit the versatility of cytoskeletal system for internalization into non-phagocytic cells, as a crucial step in their pathogenic life cycle. Enteropathogenic Escherichia coli(EPEC) andEnterohemorrhagic Escherichia coli (EHEC) were shown to form actin pedestals in host cells using type-III secretion system. Earlier, we reported that EAEC induced increase in intracellular calcium ions might have crucial role in F-actin rearrangements in INT-407 cells leading to its invasion. It was suggested that EGFR might contribute in Rck-mediated adherence and invasion of Salmonella in host cells. In the present study, we assessed the role of EAEC induced activated EGFR in human intestinal epithelial cell lines (INT-407 & HCT-15). The presence of activated EGFR was detected in membrane fractions ofeach cell line, infected with two different strains of EAEC (EAEC-T8 & EAEC-O42) separatelyfor 3h in presence and absence of Tyrphostin AG1478 (EGFR-inhibitor), by western immunoblotting using p-EGFR (Y1068) antibody. Adherence and invasion of EAEC-T8 to each cell line were checked in presence of Tyrphostin AG1478. Further, the effect of Tyrphostin AG1478 on cytoskeletal F-actin rearrangement of EAEC-T8 infected cells was assessed under confocal microscope following staining with TRITC-phalloidin. EAEC-T8 induced maximum increase in EGFR autophosphorylation at Y1068. Adherence and invasion of EAEC-T8 as well as this organism induced cytoskeletal F-actin polymerization were found to be inhibited in presence of Tyrphostin AG1478. Our study revealed that EAEC induced activated EGFR might play a major role in host cell adherence and cytoskeletal rearrangements leading to invasion of the organism in these cells.