Effects of cellular mediator agonists on cortisol and steroid acute regulatory (StAR) protein in bovine zona fasciculata (ZF) cells.
Primary cultures of bovine ZF cells were incubated for 1 h or 6h with the agonists 8-bromo-cyclic AMP (8-Br-cAMP) an activator of protein kinase A (PKA), the phorbol ester phorbol 12-myristate 13-acetate (PMA) a protein kinase C (PKC) activator, the Ca2+ ionophore, A23187, or the L-type Ca2+ channel agonist Bay K8644. Both cortisol secretion (determined by radioimmunoassay of cell medium) and cellular StAR protein levels (quantified by western blotting) were significantly increased at 6h, by all agonists. However, while all agonists stimulated cortisol secretion at 1h, StAR protein levels remained unchanged by these treatments. We conclude that in bovine ZF cells, StAR protein synthesis can be regulated by mechanisms involving activation of PKA, PKC and Ca2+ influx. However, a net increase in cellular StAR protein does not appear to be essential for the initiation for the first stage of acute steroidogenesis.
Morley
S D
SD
Department of Reproductive & Developmental Sciences, University of Edinburgh, Royal Infirmary, UK. steve.morley@ed.ac.uk
Hobkirk
J L
JL
Hall
R J
RJ
Nicol
M
M
Mason
J I
JI
Williams
B C
BC
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D006854:Hydrocortisone / Q000378:metabolism*; D007476:Ionophores / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015383:Zona Fasciculata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000098682:Steroidogenic Acute Regulatory Protein
D002120:Calcium Channel Agonists; D007476:Ionophores; D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000001:Calcimycin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D017868:Cyclic AMP-Dependent Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D006854:Hydrocortisone