The P2Y14 receptor of airway epithelial cells -: Coupling to intracellular Ca2+ and IL-8 secretion

Uridine nucleotides and UDP-glucose are endogenous molecules, which are released into the extracellular environment in a lytic manner after cell damage, as well as by regulated nonlytic mechanisms. Recently, a UDP-glucose-specific Gi protein-coupled P2Y receptor, namely P2Y,,, has been cloned. In this study, we demonstrated expression of the P2Y(14) mRNA in human lung epithelia] cells and in the epithelial cell lines A549 and BEAS-2B. Evidence of functional expression of the P2Y14 receptor in these cell lines was provided by calcium measurements after stimulation with uridine 5'-diphosphoglucose (IJDP-glc). Experiments with pertussis toxin and the Ca2+-chelator EGTA revealed participation of pertussis toxin-sensitive G(i/o)-proteins in the mobilization of Ca2+-ions from intracellular stores by UDP-glc. Moreover, UDP-glc increased secretion of the potent neutrophil chemoattractant CXCL8/IL-8 in A549 and BEAS-2B cells in a pertussis toxin-sensitive manner. Moreover, reverse transcription and quantitative polymerase chain reaction revealed that UDP-glc modulated mRNA levels of IL-8/CXCL8. However, stimulation of A549 and BEAS-2B cells with UDP-glc neither modified basal nor cytokine-induced secretion of the CXC-chemokines CXCL9/MIG, CXCLIO/IP-10, and CXCL11/1-TAC. In addition, UDP-glc did not affect proliferation of the two cell lines. In summary, our data provide evidence for a distinct physiologic role of P2Y(14) in the selective release of specific chemokines from human airway epithelial cells.