ATP stimulates interleukin-6 production via P2Y receptors in human HaCaT keratinocytes

We evaluated the role of ATP in functions of human HaCaT keratinocytes. ATP was released from HaCaT cells by changing the culture medium. Reverse transcription-polymerase chain reaction analysis revealed that HaCaT cells expressed multiple P2 purinergic receptor mRNAs. UTP was the most potent agonist to increase the intracellular Ca2+ concentration ([Ca2+]i). UTP and ATP caused the accumulation of [3H]inositol phosphates, suggesting that UTP binds to the Gq/11-coupled P2Y receptor. UTP increased IL-6 mRNA and protein levels, and the increases were inhibited by a P2 purinergic receptor antagonist (suramin, 300 μM). While a protein kinase C inhibitor (GF109203X, 10 μM) was without effect, an intracellular free Ca2+ chelator (BAPTA-AM, 50 μM) suppressed UTP-mediated IL-6 induction. These results suggest that 1) ATP is released from HaCaT cells upon physical stimulation and may act as an autocrine molecule, and 2) the stimulation of P2Y receptors causes IL-6 production via mRNA expression through [Ca2+]i elevation.