Noncoordinate regulation of de novo synthesis of cytochrome P-450 cholesterol side-chain cleavage and cytochrome P-450 17 alpha-hydroxylase/C17-20 lyase in mouse Leydig cell cultures: relation to steroid production.
The role of cAMP in the regulation of the amount and synthesis of cytochrome P-450 cholesterol side-chain cleavage (P-450scc) and cytochrome P-450 17 alpha-hydroxylase/C17-20 lyase (P-450(17 alpha) was investigated in mouse Leydig cell cultures. In the absence of cAMP, the amount of immunoreactive P-450(17 alpha) decreased to less than 5% by day 4 and was undetectable between days 7 and 11. In contrast, the amount of immunoreactive P-450scc remained relatively constant throughout the same period. Treatment of Leydig cell cultures for 4 days with 0.05 mM 8-bromo-cAMP initiated on day 7 increased the amount of P-450(17 alpha) with relatively little effect on the amount of P-450scc. The rate of de novo synthesis of each of the P-450 enzymes was studied by determining [35S]methionine incorporation into newly synthesized protein. In the absence of cAMP, de novo synthesis of P-450(17 alpha) ceased while the rate of de novo synthesis of P-450scc increased with time in culture between days 2 and 11. Treatment with cAMP initiated on day 7 of culture caused a time-dependent increase in the rate of de novo synthesis of P-450(17 alpha) on days 9 and 11 equivalent to 40% and 60%, respectively, of that observed in freshly isolated Leydig cells. The rate of de novo synthesis of P-450scc was increased 2-fold relative to untreated cultures on days 9 and 11. De novo synthesis of P-450(17 alpha) ceased when cAMP was removed on day 11 and restored when cAMP was added again on day 13 of culture.(ABSTRACT TRUNCATED AT 250 WORDS)
Anakwe
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Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor 48109-0278.
Payne
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AH
D000818:Animals; D000918:Antibody Specificity; D002478:Cells, Cultured; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000096:biosynthesis*; D000242:Cyclic AMP / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D015971:Gene Expression Regulation, Enzymologic; D015151:Immunoblotting; D007985:Leydig Cells / Q000201:enzymology*; D008297:Male; D051379:Mice; D013254:Steroid 17-alpha-Hydroxylase / Q000096:biosynthesis*; D013256:Steroids / Q000096:biosynthesis*; D013462:Sulfur Radioisotopes
D013256:Steroids; D013462:Sulfur Radioisotopes; D000242:Cyclic AMP; D013254:Steroid 17-alpha-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme