Gonadotropin release and redistribution of calcium-activated, phospholipid-dependent protein kinase in phorbol-stimulated rat pituitary cells.
The effect of phorbol esters on calcium-activated, phospholipid-dependent kinase (protein kinase C) and luteinizing hormone (LH) secretion was examined in cultured rat anterior pituitary cells. The potent tumor promoter 12-O-tetra-decanoylphorbol-13-acetate (TPA) stimulated LH secretion and activated pituitary protein kinase C in the presence of calcium and phosphatidylserine. The enzyme activity present in cytosol and particulate fractions was eluted at about 0.05 M NaCl during DE52-cellulose chromatography. Preincubation of pituitary cells with TPA markedly decreased cytosolic protein kinase C activity and increased enzyme activity in the particulate fraction. The maximal TPA-induced change in enzyme activity, with a 76% decrease in cytosol and a 4.3-fold increase in the particulate fraction, occurred within 10 min. The dose-dependent changes in protein kinase C redistribution in TPA-treated cells were correlated with the stimulation of LH release by the phorbol ester. These results suggest that activation of protein kinase C by TPA is associated with intracellular redistribution of the enzyme and is related to the process of secretory granule release from gonadotrophs.
D000818:Animals; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D010703:Phorbol Esters; D007986:Luteinizing Hormone; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate