THE ROLE OF PROTEIN-KINASE-C IN INTERLEUKIN-1 AND TUMOR NECROSIS FACTOR-ALPHA INDUCTION OF FIBROBLASTS TO PRODUCE AND RELEASE GRANULOCYTE-MACROPHAGE COLONY-STIMULATING ACTIVITY

  • 1 September 1990
    • journal article
    • research article
    • Vol. 18  (8) , 888-892
Abstract
The process of signal transduction by interleukin 1 (IL-1) or tumor necrosis factor alpha (TNF.alpha.) for the production of hematopoietic growth factors by cultured fibroblasts was studied using inhibitors for protein kinase C, cyclic nucleotide-dependent protein kinases, calmodulin-dependent protein kinases, and the Na+-H+ antiport system. The protein kinase C inhibitor H-7 was shown to inhibit both IL-1.beta.- and TNF.alpha.-induced granulocyte-macrophage colony-stimulating activity (GM-CSA) production and release from cultured fibroblasts in a dose-dependent manner, with 40 .mu.M H-7 demonstrating maximum suppression of the GM-CSA response. In addition, 100-200 nM staurosporine, a more potent inhibitor of protein kinase C, also completely suppressed GM-CSA from IL-1.beta.- and TNF.alpha.-induced fibroblasts. In contrast, a potent inhibitor of cyclic nucleotide-dependent protein kinases, HA 1004, showed no effect when used at 10-40 .mu.m. In addition, an inhibitor of calmodulin-induced protein kinases, W-7, also showed no effect when used at 10-30 .mu.M. Prior incubation with H-7 did not inhibit the ability of fibroblasts to subsequently respond to IL-1.beta. or TNF.alpha., nor did H-7 directly inhibit the granulocyte-macrophage colony-forming assay. Both dibutyryl cyclic adenosine monophosphate (10-30 .mu.M) and forskolin (1-100 nM), activators of adenylate cyclase, in the presence or absence of the phosphodiesterase inhibitor isobutylmethylxanthine, failed to stimulate a GM-CSA response from cultured fibroblasts, indicating a lack of effect of cyclic nucleotide-dependent protein kinases. Furthermore, the addition of H-7 30 min after induction with IL-1.beta. or TNF.alpha. showed little effect on the synthesis of GM-CSA by cultured fibroblasts, indicating that the signal transduction process probably occurred within the first 30 min of ligand-receptor interaction. Finally, amelioride, an inhibitor of the Na+-H+ antiport, was shown to inhibit IL-1.beta.-induced GM-CSA in a dose-dependent manner.

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