Mechanism of thrombin-induced arachidonic acid release in osteoblast-like cells.
In a previous study, we have reported that thrombin stimulates phosphatidylcholine hydrolysis by phospholipase (PL) D, but has little effect on phosphoinositide hydrolysis by PLC in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the mechanism of the thrombin-induced arachidonic acid (AA) release in MC3T3-E1 cells. Thrombin stimulated AA release dose dependently in the range between 0.1 and 1 U/ml. Quinacrine, a PLA2 inhibitor, suppressed the thrombin-induced AA release. In addition, quinacrine also suppressed the thrombin-induced prostaglandin E2 synthesis in these cells. On the other hand, propranolol, which is known to inhibit phosphatidic acid phosphohydrolase, did not affect the thrombin-induced AA release. 1(6-((17beta-3-Methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H- pyrrole-2,5-dione (U-73122), a PLC inhibitor, had no effect on the AA release by thrombin. In addition, 1,6-bis-(cyclohexyloximinocarbonylamino)-hexane (RHC-80267), a selective inhibitor of diacylglycerol lipase, had little effect on the thrombin-induced AA release. Neither propranolol, U-73122 nor RHC-80267 affect the thrombin-induced prostaglandin E2 synthesis. These results strongly suggest that thrombin induces AA release not by phosphatidylcholine hydrolysis by PLD nor phosphoinositide hydrolysis by PLC but mainly by PLA2 in osteoblast-like cells.
Suzuki
A
A
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Kozawa
O
O
Shinoda
J
J
Watanabe-Tomita
Y
Y
Saito
H
H
Oiso
Y
Y
D016475:3T3 Cells; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D003512:Cyclohexanones / Q000494:pharmacology; D015232:Dinoprostone / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D008071:Lipoprotein Lipase / Q000037:antagonists & inhibitors; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D010711:Phosphatidate Phosphatase / Q000037:antagonists & inhibitors; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism; D054467:Phospholipases A2; D011433:Propranolol / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D011796:Quinacrine / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
D003512:Cyclohexanones; D004791:Enzyme Inhibitors; D004963:Estrenes; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D016718:Arachidonic Acid; C036535:1,6-bis(cyclohexyloximinocarbonyl)hexane; D011433:Propranolol; D010741:Phospholipases A; D008071:Lipoprotein Lipase; D054467:Phospholipases A2; D010711:Phosphatidate Phosphatase; D010738:Type C Phospholipases; D013917:Thrombin; D011796:Quinacrine; D015232:Dinoprostone