S1771 Interferon-γ Selectively Modulates the Ability of EGF to Activate EGFR Signaling and Reverses Its Inhibitory Effects On K + Channel Activity in T84 Colonic Epithelial Cells

Abstract

BBE cells in the presence or absence of mature microRNAs and luciferase activity or GFP expression was analyzed. HT29-Cl.19A cells were infected with enteropathogenic E. coli (EPEC) and PepT1 and microRNAs levels were quantified by Northern blot and real-time RT-PCR. Results: Among the microRNAs tested, expression level of miR-619 was decreased following Caco2-BBE cell differentiation, and this is accompanied with an opposite pattern of PepT1 expression. This observation suggests that miR-619 is involved in PepT1 expression. Transfection of Caco2-BBE cells with miR-619 significantly decreased PepT1 mRNA and protein expression levels and transport activity, whereas other microRNA candidates did not exhibit any effects. This result demonstrates the specificity of miR-619 in the regulation of PepT1 expression. Importantly, miR-619 significantly decreased the luciferasse activity as well as GFP expression, indicating that miR-619 effectively binds PepT1 3'UTR mRNA. Furthermore, infection of HT29-Cl.19A with EPEC induced PepT1 expression and decreased miR-619 expression level, suggesting that this microRNA is implicated in the regulation of colonic PepT1 expression under pathological states. Conclusions: Here we demonstrate, for the first time, that PepT1 expression can be regulated by microRNAs. Our study reveals a novel mechanism underlying the regulation of this transporter, as well as open new insights to modulate epithelial transport.