Role of protein kinase C in bradykinin-induced prostaglandin formation in osteoblasts.
Bradykinin (1 microM, 5 min) induced translocation of protein kinase C (PKC) to the plasma membrane fraction in osteoblastic MC3T3-E1 cells. Bradykinin also enhanced the binding of phorbol 12,13-dibutyrate (PDBu) to intact cells, a measure of PKC activation. Addition of bradykinin (1 microM) to cells preincubated with [3H]PDBu (10 nM, 20 min) caused an increase in specific PDBu binding that was maximal after 5-10 min. The bradykinin-induced enhancement of PDBu binding was seen at 1 nM and was maximal at 10 nM. The bradykinin B1 receptor agonist des-Arg9-bradykinin (1 microM) did not enhance specific PDBu binding to intact MC3T3-E1 cells. PDBu at and above 3 nM stimulated the formation of prostaglandin E2 (PGE2) in MC3T3-EI cells. This stimulatory effect was seen after 15-20 min incubation. The Ca2+ ionophore A23187 at and above 1 microM induced a rapid (within seconds) burst of PGE2 formation in MC3T3-E1 cells. The effect of PDBu and A23187 on PGE2 formation was synergistic. The PKC inhibitor staurosporine (200 nM) inhibited basal as well as bradykinin-induced prostaglandin-formation in MC3T3-E1 cells.


CONCLUSIONS
bradykinin enhances PKC activation in osteoblastic MC3T3-E1 cells. This kinase activation may be involved in bradykinin-induced prostaglandin formation.
Ljunggren
O
O
Department of Internal Medicine, University Hospital, Uppsala, Sweden.
Fredholm
B B
BB
Nordstedt
C
C
Ljunghall
S
S
Lerner
U H
UH
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D015232:Dinoprostone / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D006854:Hydrocortisone / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011453:Prostaglandins / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D011453:Prostaglandins; C024626:bradykinin, des-Arg(9)-; D015240:Phorbol 12,13-Dibutyrate; D000001:Calcimycin; D011493:Protein Kinase C; D019311:Staurosporine; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D001920:Bradykinin; D006854:Hydrocortisone; D007213:Indomethacin