title: Interleukin-6 synthesis induced by prostaglandin E2: cross-talk regulation by protein kinase C.
abstract: We previously showed that prostaglandin E2 (PGE2) stimulates multiple intracellular signaling pathways as follows: by activation of adenylate cyclase; phosphoinositide (PI)-hydrolyzing phospholipase C and phosphatidylcholine (PC)-hydrolyzing phospholipase D; and by induction of Ca2+ influx in osteoblast-like MC3T3-E1 cells. In this study, we investigated the effect of PGE2 on the synthesis of interleukin-6 (IL-6) and its regulatory mechanism in MC3T3-E1 cells. PGE2 significantly stimulated IL-6 secretion in a dose-dependent manner in the range between 1 nmol/L and 10 micromol/L. A23187, a calcium ionophore, or dibutyryl-cAMP significantly induced IL-6 secretion. The effect of a combination of A23187 and dibutyryl-cAMP on IL-6 secretion was additive. The depletion of extracellular Ca2+ by EGTA reduced the PGE2-induced IL-6 secretion. EP1 receptor antagonist inhibited the PGE2-induced IL-6 secretion. H-89, an inhibitor of cAMP-dependent protein kinase, decreased the PGE2-induced IL-6 secretion. EP2 receptor agonist alone stimulated IL-6 secretion. However, EP4 receptor antagonist had little effect on IL-6 secretion. Calphostin C, a specific inhibitor of protein kinase C (PKC), enhanced the secretion of IL-6 induced by PGE2. The stimulative effect of PGE2 on IL-6 secretion was significantly enhanced in PKC downregulated MC3T3-E1 cells. Pertussis toxin enhanced PGE2-induced IL-6 secretion. These results strongly suggest that PGE2 stimulates IL-6 synthesis through both Ca2+ mobilization from extracellular space via EP1 receptor and cAMP production via EP2 receptor in osteoblast-like cells, and that the PKC activation by PGE2 itself regulates oversynthesis of IL-6.
authors.affiliation: Department of Pharmacology, Gifu University School of Medicine, Japan.
authors.forename: O
authors.initials: O
authors.lastname: Kozawa
authors.forename: A
authors.initials: A
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Tokuda
authors.forename: T
authors.initials: T
authors.lastname: Kaida
authors.forename: T
authors.initials: T
authors.lastname: Uematsu
mesh_terms: D016475:3T3 Cells; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D015232:Dinoprostone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis*; D007476:Ionophores / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D051379:Mice; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018078:Receptors, Prostaglandin E / Q000819:agonists / Q000378:metabolism; D058307:Receptors, Prostaglandin E, EP2 Subtype; D013449:Sulfonamides
chemical_list: D002614:Chelating Agents; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D007476:Ionophores; D007546:Isoquinolines; D009281:Naphthalenes; C545645:Ptger2 protein, mouse; D018078:Receptors, Prostaglandin E; D058307:Receptors, Prostaglandin E, EP2 Subtype; D013449:Sulfonamides; D000001:Calcimycin; D004533:Egtazic Acid; D003994:Bucladesine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C058819:calphostin C; D015232:Dinoprostone; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D002118:Calcium