Prostaglandin F2 alpha stimulates cAMP phosphodiesterase via protein kinase C in cultured human granulosa cells.
To investigate the involvement of cyclic AMP phosphodiesterase in the antigonadotrophic actions of prostaglandin F2 alpha (PGF2 alpha), human granulosa cells were cultured in serum-supplemented medium for 72 h, treated for 30 min with cloprostenol or phorbol myristate acetate (PMA) and then exposed to human chorionic gonadotrophin (hCG) +/- isobutyl-methylxanthine (IBMX) for a further 4 h. In the absence of IBMX, cloprostenol and PMA inhibited hCG-stimulated progesterone production. However, in the presence of 0.5 mM IBMX, inhibition of phosphodiesterase prevented these antigonadotrophic effects. Phosphodiesterase activity was assessed by a novel direct assay performed on intact cells after 3 days of culture. PGF2 alpha, cloprostenol and 4 beta-PMA all enhanced cAMP degradation whilst an inactive phorbol ester (4 alpha-PMA) had no effect. Down-regulation of protein kinase C by 4 beta-PMA pre-treatment prevented the subsequent stimulation of phosphodiesterase activity by both cloprostenol and 4 beta-PMA. We conclude that the antigonadotrophic actions of PGF2 alpha in cultured human granulosa cells involve a stimulation of cAMP phosphodiesterase mediated via protein kinase C.
Michael
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AE
MRC/AFRC Comparative Physiology Research Group, Institute of Zoology, Regent's Park, London, U.K.
Webley
G E
GE
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000328:Adult; D002478:Cells, Cultured; D003008:Cloprostenol / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D015237:Dinoprost / Q000502:physiology*; D005260:Female; D006107:Granulosa Cells / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D011374:Progesterone / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D003008:Cloprostenol; D011374:Progesterone; D015237:Dinoprost; D000242:Cyclic AMP; D011493:Protein Kinase C; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D013755:Tetradecanoylphorbol Acetate; D015056:1-Methyl-3-isobutylxanthine