RT Journal Article SR Electronic T1 Cross-Talk between Gs- and Gq-Coupled Pathways in Regulation of Interleukin-4 by A2B Adenosine Receptors in Human Mast Cells JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 727 OP 735 DO 10.1124/mol.106.022780 VO 70 IS 2 A1 Sergey Ryzhov A1 Anna E. Goldstein A1 Italo Biaggioni A1 Igor Feoktistov YR 2006 UL http://molpharm.aspetjournals.org/content/70/2/727.abstract AB Human mast cells express functional A2A and A2B adenosine receptors. However, only stimulation of A2B, not A2A, leads to secretion of interleukin (IL)-4, an important step in adenosine receptor-mediated induction of IgE synthesis by B-cells. In this study, we investigate intracellular pathways that link stimulation of A2B receptors to IL-4 up-regulation in HMC-1 mast cells. Both A2A and A2B receptors couple to Gs proteins and stimulate adenylate cyclase, but only A2B stimulates phospholipase Cβ through coupling to Gq proteins leading to activation of protein kinase C and calcium mobilization. Inhibition of phospholipase Cβ completely blocked A2B receptor-dependent IL-4 secretion. The protein kinase C inhibitor 2-{8-[(dimethylamino)-methyl]-6,7,8,9-tetrahydropyrido[1,2-a]indol-3-yl}-3-(1-methyl-1H-indol-3-yl)maleimide (Ro-32-0432) had no effect on A2B receptor-mediated IL-4 secretion but inhibited phorbol 12-myristate 13-acetate-stimulated IL-4 secretion. In contrast, chelation of intracellular Ca2+ inhibited both A2B receptor- and ionomycin-dependent IL-4 secretion. This Ca2+-sensitive pathway probably includes calcineurin and nuclear factor of activated T cells, because A2B receptor-dependent IL-4 secretion was blocked with cyclosporin A or 11R-VIVIT peptide. Gs-linked pathways also play a role in the A2B receptor-dependent stimulation of IL-4 secretion; inhibition of adenylate cyclase or protein kinase A attenuated A2B receptor-dependent IL-4 secretion. Although stimulation of adenylate cyclase with forskolin did not increase IL-4 secretion on its own, it potentiated the effect of Pasteurella multocida toxin by 2-fold and ionomycin by 3-fold. Both forskolin and stimulation of A2B receptors up-regulated NFATc1 protein levels. We conclude that A2B receptors up-regulate IL-4 through Gq signaling that is potentiated via cross-talk with Gs-coupled pathways.