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 G(i) protein-coupled P2Y receptor, namely P2Y(14), has been cloned. In this study, we demonstrated expression of the P2Y(14) mRNA in human lung epithelial cells and in the epithelial cell lines A549 and BEAS-2B. Evidence of functional expression of the P2Y(14) receptor in these cell lines was provided by calcium measurements after stimulation with uridine 5'-diphosphoglucose (UDP-glc). Experiments with pertussis toxin and the Ca(2+)-chelator EGTA revealed participation of pertussis toxin-sensitive G(i/o)-proteins in the mobilization of Ca(2+)-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, CXCL10/IP-10, and CXCL11/I-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.