Interleukin-1 stimulation of arachidonic acid release from human synovial fibroblasts; blockade by inhibitors of protein kinases and protein synthesis.
Addition of IL-1 (interleukin-1) to human synovial fibroblasts radiolabelled with [3H]arachidonic acid caused a linear dose-dependent increase in arachidonic acid release and a transient rise in labelled diacylglycerol. Protein kinase C activators PMA 4-phorbol 12-myristate 13-acetate and DiC8 (1,2-dioctanoyl-sn-glycerol) also increased arachidonic acid release, but the time course observed with PMA was different from that of IL-1. When cultures were treated with PMA for 16-24 h to down regulate protein kinase C, the ability of IL-1 to increase arachidonic acid release persisted to the same extent as in nontreated cultures. In contrast, PMA pretreatment prevented the eight-fold stimulation of arachidonic acid release in response to PMA observed in cultures not previously exposed to PMA. To examine the role of other kinases in IL-1 stimulated arachidonic acid release, cultures were treated with H-7 (1-(5-isoquinolinesulphonyl)-2-methylpiperazine dichloride), H-8 (N-[2-(methylamino) ethyl]-5-isoquinolinesulphonamide dichloride), HA1004 (N-(2-guanidoinoethyl)-5-isoquinolinesulphonamide hydrochloride), and staurosporine. IL-1 stimulation of arachidonic acid release was blocked by H-7, H-8 and staurosporine. H-7 was a more potent inhibitor than H-8, suggesting that cAMP dependent kinase did not mediate IL-1 action. Addition of H-7 at various times following IL-1 decreased IL-1 stimulated arachidonic acid release, suggesting that continued protein kinase activity was necessary for IL-1 action. Cycloheximide and actinomycin D inhibited the stimulation of arachidonic acid release by IL-1, PMA or DiC8. The addition of cycloheximide or actinomycin D 15-45 min after IL-1 also inhibited IL-1 stimulated arachidonic acid release, indicating that continued protein synthesis was required for IL-1 action. These results suggest that IL-1 stimulation of acylhydrolyase activity in human synovial cells occurs by a mechanism requiring continued protein synthesis and protein kinase activity and that neither protein kinase C nor cAMP dependent protein kinase is involved.
Cisar
L A
LA
Department of Cell Biology, University of Medicine and Dentistry of New Jersey, School of Osteopathic Medicine, Stratford 08084.
Schimmel
R J
RJ
Mochan
E
E
D001095:Arachidonic Acids / Q000378:metabolism*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D007700:Kinetics; D011493:Protein Kinase C / Q000378:metabolism; D047428:Protein Kinase Inhibitors; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D013582:Synovial Fluid / Q000166:cytology / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D001095:Arachidonic Acids; D007375:Interleukin-1; D047428:Protein Kinase Inhibitors; D011500:Protein Synthesis Inhibitors; D003513:Cycloheximide; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate