title: Protein kinase C in adrenal cells: possible role in regulation of steroid synthesis.
abstract: Y-1 adrenal tumor cells and rat fasciculata cells were shown to possess an enzyme with the properties of protein kinase C. Activity was stimulated by Ca2+ and phospholipid (specifically phosphatidylserine). Enzyme activity was stimulated by addition of phorbol ester to a cell homogenate (ED50 10 nM) and inhibited by trifluoperazine (ID50 10 microM). ACTH and cyclic AMP added to Y-1 cells increased the activity of protein kinase C. Dose-response curves with ACTH showed that the hormone was effective in stimulating protein kinase C at lower concentrations than those required to increase steroid synthesis. When phorbol ester was added to Y-1 cells, total kinase C activity was diminished. Neither phorbol ester nor ACTH causes redistribution of protein kinase C between membranes and cytosol. Phorbol ester also stimulates steroid production by Y-1 cells. Protein kinase C phosphorylates 5 proteins in Y-1 cells (67, 61, 32, 16 and less than 14.4 kDa). Puromycin and cycloheximide increase the activity of protein kinase C in adrenal cells. It is concluded that protein kinase C may play an ancillary role in regulation of adrenal steroid synthesis but does not mediate the classical steroidogenic response that results from activation of adenylate cyclase by ACTH.
mesh_terms: D004092:20-alpha-Dihydroprogesterone / Q000096:biosynthesis*; D000310:Adrenal Gland Neoplasms / Q000378:metabolism* / Q000473:pathology; D000311:Adrenal Glands / Q000166:cytology; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000032:analysis; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003600:Cytosol / Q000032:analysis; D051379:Mice; D010703:Phorbol Esters / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology; D011374:Progesterone / Q000031:analogs & derivatives*; D011493:Protein Kinase C / Q000502:physiology*; D011691:Puromycin / Q000494:pharmacology; D051381:Rats
chemical_list: D010703:Phorbol Esters; D010743:Phospholipids; D004092:20-alpha-Dihydroprogesterone; D011691:Puromycin; D011374:Progesterone; D000324:Adrenocorticotropic Hormone; D003513:Cycloheximide; D011493:Protein Kinase C; D002118:Calcium