Phorbol ester, retinoic acid and diacylglycerol decrease ecto- but increase total basal-protein kinase activity of human fibroblasts.
Studies have been carried out on intact human lung fibroblasts (HLF) in situ to investigate the effect of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and the anti-tumor promoter retinoic acid (RA) on ecto-protein kinases. The ecto-kinase reaction of the HLF-cells was cAMP-independent, showed an apparent Km for ATP of 6.99 +/- 0.35 (microM) and was substantially inhibited by TPA and RA. With the notable exception of a approximately 57 kD phosphoprotein both compounds decreased the overall phosphorylation of intact cells. In contrast to RA-treatment, however, TPA caused the release of a high molecular weight (approximately 210 kD) phosphoprotein from the HLF. RA was the most potent retinoid in reducing ecto-kinase activity. The physiological modulators of protein kinase C: 1,2- and 1,3-diolein as well the synthetic 1,2-dioctanoylglycerol decreased the ecto-kinase activity to an extent similar to that of TPA. The drop in ecto-kinase activity of HLF-cells in situ caused by TPA, RA and the diacylglycerols was accompanied by an increase in total basal-(Mg++-dependent) protein kinase activity present in extracts of treated cells. The results suggest an important role of ecto-kinase in the response of intact cells to TPA and RA.
D002478:Cells, Cultured; D004075:Diglycerides / Q000494:pharmacology*; D005110:Extracellular Space / Q000378:metabolism; D005347:Fibroblasts; D005989:Glycerides / Q000494:pharmacology*; D006801:Humans; D008168:Lung / Q000166:cytology; D008970:Molecular Weight; D010703:Phorbol Esters / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D012176:Retinoids / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology*
D004075:Diglycerides; D005989:Glycerides; D010703:Phorbol Esters; D010750:Phosphoproteins; D012176:Retinoids; D014212:Tretinoin; D011494:Protein Kinases; C034454:ectoprotein kinase