Regulation of side-chain cleavage enzyme and 3 beta-hydroxysteroid dehydrogenase by Ca2+ second messenger and protein kinase C systems in the placenta of the cow.
The steroidogenic activity of the bovine placenta is not modulated by cyclic nucleotide-mediated mechanisms. However, both translocation of intracellular Ca2+ and influx of extracellular Ca2+ activate the side-chain cleavage enzyme and 3 beta-hydroxysteroid dehydrogenase. Protein kinase C activation in concert with Ca2+ mobilization also activates the side-chain cleavage enzyme. Cholesterol availability is a rate-limiting factor. Using polyclonal antibodies against bovine adrenal cytochrome P-450scc, the presence of P-450scc was demonstrated in both placental and luteal tissues. The cytochrome P-450scc was then localized, using gold-staining electron microscopy, in the mononuclear cells but not the binuclear cells of the placentome. The results suggest that cholesterol is metabolized by the mononuclear cell to pregnenolone, where it is further metabolized to progesterone by the mononuclear and binuclear cells.
Shemesh
M
M
Department of Hormone Research, Kimron Veterinary Institute, Bet Dagan, Israel.
Hansel
W
W
Strauss
J F
JF
Shore
L S
LS
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002450:Cell Communication; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism*; D005260:Female; D010920:Placenta / Q000187:drug effects / Q000502:physiology*; D011247:Pregnancy; D011374:Progesterone / Q000096:biosynthesis; D011493:Protein Kinase C / Q000378:metabolism*
D000001:Calcimycin; D011374:Progesterone; D015096:3-Hydroxysteroid Dehydrogenases; D002786:Cholesterol Side-Chain Cleavage Enzyme; D011493:Protein Kinase C; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine