title: Regulation of purinergic signaling by prostaglandin E2 in murine macrophages.
abstract: Extracellular nucleotides are primary signals for tissue injury, acting together with various chemical mediators such as prostanoids at the inflammatory site. We investigated whether prostaglandin E2 (PGE2) affects purinergic signaling in murine J774 macrophages. J774 cells expressed four different purinoceptor mRNAs: the ionotropic P2X4 and P2X7 receptors and G-protein-coupled P2Y2 and P2Y6 receptors. Functional responses mediated by these purinoceptor subtypes were confirmed by measurement of intracellular Ca2+ concentration ([Ca2+]i) in fura-2-loaded cells. Thus, low concentrations (10 microM) of ATP (P2Y2 agonist) and UDP (P2Y6 agonist) evoked Ca2+ transient in a phospholipase C (PLC)-dependent manner, whereas the P2X7 agonist benzoylbenzoyl-ATP (BzATP, 500 microM) caused a sustained rise in [Ca2+]i. Furthermore, ivermectin, an activator of the P2X4-receptor channel, enhanced the ATP-induced [Ca2+]i elevation. PGE2 inhibited ATP- and UDP-induced [Ca2+]i elevation, without affecting the BzATP-induced sustained [Ca2+]i elevation. Stimulation of J774 cells by UDP or BzATP increased the production of macrophage inflammatory peptide-alpha (MIP-alpha). PGE2 abolished the UDP-induced MIP-alpha production, but not the BzATP-induced one. These results demonstrate that purinergic signalings in macrophages were regulated by PGE2 in a subtype-specific manner. The different inhibitory effects on distinct purinoceptor functions may be related to the anti-inflammatory property of PGE2.
authors.affiliation: Laboratory of Pharmacology, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki-shi, Gunma, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ito
authors.forename: Isao
authors.initials: I
authors.lastname: Matsuoka
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D054405:Chemokine CCL3 / Q000187:drug effects / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000187:drug effects* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism
chemical_list: D054405:Chemokine CCL3; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D010738:Type C Phospholipases; D015232:Dinoprostone; D002118:Calcium