Prostaglandin D2 induces interleukin-6 synthesis via Ca2+ mobilization in osteoblasts: regulation by protein kinase C.
We previously showed that prostaglandin (PG) D2 stimulates Ca2+ influx from extracellular space and activates phosphoinositidic (PI)-hydrolyzing phospholipase C and phosphatidylcholine (PC)-hydrolyzing phospholipase D independently from PGE2 or PGF2alpha in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of PGD2 on the synthesis of interleukin-6 (IL-6) and its regulatory mechanism in MC3T3-E1 cells. PGD2 significantly stimulated IL-6 synthesis dose-dependently in the range between 10 nM and 10 microM. The depletion of extracellular Ca2+ by EGTA reduced the PGD2-induced IL-6 synthesis. TMB-8, an inhibitor of intracellular Ca2+ mobilization, significantly inhibited the PGD2-induced IL-6 synthesis. On the other hand, calphostin C, a specific inhibitor of protein kinase C (PKC), enhanced the synthesis of IL-6 induced by PGD2. In addition, U-73122, an inhibitor of phospholipase C, and propranolol, a phosphatidic acid phosphohydrolase inhibitor, enhanced the PGD2-induced IL-6 synthesis. These results strongly suggest that PGD2 stimulates IL-6 synthesis through intracellular Ca2+ mobilization in osteoblasts, and that the PKC activation by PGD2 itself regulates the over-synthesis of IL-6.
Tokuda
H
H
Department of Internal Medicine, Chubu National Hospital, National Institute for Longevity Sciences, Obu, Japan.
Kozawa
O
O
Harada
A
A
Uematsu
T
T
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002999:Clone Cells; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis*; D051379:Mice; D009281:Naphthalenes / Q000494:pharmacology; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D015230:Prostaglandin D2 / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology
D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D004963:Estrenes; D015850:Interleukin-6; D009281:Naphthalenes; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D011433:Propranolol; D011493:Protein Kinase C; C058819:calphostin C; D015230:Prostaglandin D2; D002118:Calcium