Invasion of human epithelial cells by Pseudomonas aeruginosa involves Src-like tyrosine kinases p60Src and p59Fyn

Pseudomonas aeruginosa plays a major role in respiratory tract infections o r sepsis in patients with cystic fibrosis or upon suppression of the immune system. Several P. aeruginosa strains have been shown to be internalized b y human epithelial cells; however, the molecular mechanisms of the invasion process are poorly characterized. Here, we show that the internalization o f P. aeruginosa into human epithelial cells results in and requires activat ion of the Src-like tyrosine kinases p59Fyn and p60Src and the consequent t yrosine phosphorylation of several eukaryotic proteins. The significance of Src-like tyrosine kinase activation is shown by an almost complete blockad e of P. aeruginosa internalization, but not adhesion, upon inhibition of Sr c-like tyrosine kinases. Likewise, inhibition of P. aeruginosa binding to C FTR, which has been shown to block P. aeruginosa internalization, prevents Src and Fyn activation, supporting a pivotal role of Src-like tyrosine kina ses for invasion by P. aeruginosa.