The mechanism of bradykinin-induced arachidonic acid release in osteoblast-like MC3T3-E1 cells phospholipase A2 activation by bradykinin and its regulation by protein kinase C and calcium.
In the present study, we investigated the mechanism by which bradykinin (BK) enhances [3H]arachidonic acid release in murine osteoblast-like MC3T3-E1 cells prelabeled with [3H]arachidonic acid. BK enhanced [3H]arachidonic acid release in a time- and concentration-dependent manner, when cells were stimulated in the presence, but not in the absence, of extracellular Ca2+. It appears that the BK-induced [3H]arachidonic acid release was attributed to the activation of phospholipase A2, since a phospholipase A2 inhibitor, mepacrine, significantly inhibited the BK enhancement of [3H]arachidonic acid release whereas a diacylglycerol lipase inhibitor, RHC80267, failed to do so. Furthermore, it was found that a protein kinase C inhibitor, staurosporine, and down-regulation of protein kinase C by prolonged exposure of cells to phorbol 12-myristate 13-acetate inhibited the BK-induced [3H]arachidonic acid release. These results provide evidence that BK stimulation of MC3T3-E1 cells activates phospholipase A2 to liberate arachidonic acid by the mechanism which involves both Ca2+ and protein kinase C.
Suzuki
N
N
Department of Orthopaedic Surgery, Gifu University, School of Medicine, Japan.
Matsunaga
T
T
Kanaho
Y
Y
Nozawa
Y
Y
D016475:3T3 Cells / Q000378:metabolism; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001920:Bradykinin / Q000494:pharmacology* / Q000502:physiology; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D051379:Mice; D010006:Osteoblasts / Q000201:enzymology / Q000378:metabolism*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D011796:Quinacrine / Q000494:pharmacology; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D016718:Arachidonic Acid; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2; D011796:Quinacrine; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D001920:Bradykinin; D002118:Calcium