UTP and ATPgammaS Induce Mucin Secretion via Ca2+ Dependant Pathways in Human Nasal Epithelial Cells

Abstract

BACKGROUND AND OBJECTIVES: Nucleotides such as adenosine triphosphate (ATP) and uridine-5-triphosphate (UTP) play fundamental roles in the early stage of secretion in nasal epithelial cells via P2Y receptor. In the present study, we examined the expression pattern of P2Y subtypes and their functions on Ca2+ influx ([Ca2+]i) in normal human nasal epithelial (NHNE) cells. We also examined the effect of UTP (agonist for P2Y2) and ATPgammaS (agonist for P2Y11) on mucin secretion and mucin gene expression. MATERIALS AND METHOD: The expression pattern of P2Y receptors and mRNA levels of MUC5AC, MUC5B and MUC8 were examined after treatment with UTP and ATPgammaS by RT-PCR. Mucin was quantitated by immunoblotting assay. We measured the [Ca2+]i in NHNE cells with a double perfusion chamber. RESULTS: Two uracil-sensitive receptors (P2Y2, P2Y4) and two adenine-sensitive receptors (P2Y1, P2Y11) were expressed in NHNE cells. UTP and ATPgammaS increased [Ca2+]i via caffeine-sensitive pathways, and these two agonists stimulated mucin secretion to a similar magnitude without their gene enhancement. In addition, the mucin stimulatory effects subsided when the intracellular Ca2+ was removed by 2-bis (2-aminophenoxy) ethane-N, N, N', N'-tetraacetic acid-acetoxymethyl ester. CONCLUSION: Our study showed that P2Y2 and P2Y11 receptors were expressed in NHNE cells and that their agonists, UTP and ATPgammaS, act as secretogogues on mucin secretion via Ca2+-dependent pathways.