Enteropathogenic Escherichia coli induces modification of the focal adhesions of infected host cells

Summary Enteropathogenic Escherichia coli (EPEC) is a human-specific pathogen that causes severe diar- rhoea in young children. The disease involves inti- mate interaction between the pathogen and the brush border of enterocytes. During infection, EPEC uses a type III secretion system (TTSS) to inject several pro- teins into the infected cells, and these effector pro- teins modify specific processes in the host cell. We show that, upon infection, EPEC induces detachment of the infected host cells from the substratum, modi- fication of focal adhesions (FA) in the infected cells and specific dephosphorylation of focal adhesion kinase (FAK). We also show that EPEC-induced cell detachment is dependent on FAK expression by the infected cells. Finally, we demonstrate that cell detachment, FA modification and FAK dephosphory- lation are dependent on functional TTSS in the infect- ing EPEC. These results suggest that EPEC is using its TTSS to inject protein(s) into the infected cells, which can induce FAK dephosphorylation, as well as FAK-dependent FA modification and cell detachment. These processes are specific and probably play an important role in EPEC virulence.