TY - JOUR
T1 - The role of cholesterol esterification in ovarian steroidogenesis
T2 - Studies in cultured swine granulosa cells using a novel inhibitor of acyl coenzyme a: Cholesterol acyltransferase
AU - Veldhuis, Johannes D.
AU - Strauss, Jerome F.
AU - Silavin, Susan L.
AU - Kolp, Lisa A.
AU - Klase, Patricia A.
AU - Juchter, Diana
AU - Garmey, James
PY - 1985
Y1 - 1985
N2 - We have used a novel competitive inhibitor of acyl coenzyme A:cholesterol acyltransferase (ACAT), Sandoz compound 58-035 [3-(decyldimethyl-silyl)N-[2-(4-methylghenylph- phenylethyl propanamide], to assess the importance of the cholesterol esterification reaction in ovarian steroidogenesis. Compound 58-035 markedly (≥96%) inhibited ACAT activity of swine ovarian microsomes in a dose-dependent (0.1-3.5 µg/ml) fashion. In addition, treatment of cultured granulosa pells with this fatty acylamide effectively (≥98%) suppressed hormonally stimulated cholesterol esterification, as assessed by the incorporation of [3H]oleic acid into cholesteryl ester. Accordingly, we used this inhibitor to test the role of cholesterol esterification in ovarian cells. In cultures with limited or no serum supplementation, long term (2- to 6-day) treatment of granulosa cells with compound 58-035 significantly increased basal progesterone production and amplified by 2- to 10-fold the stimulatory actions of trophic hormones, such as estradiol, FSH, estradiol combined with FSH, or insulin. The amplifying effect of ACAT inhibition on hormone- stimulated progesterone production could be mimicked by providing exogenous cholesterol substrate in the form of low density lipoprotein (LDL). Cotreatment with compound 58-035 and LDL resulted in no further augmentation of steroidogenesis. In contrast to the facilitative effects of compound 58-035 in longer term cultures, this ACAT inhibitor did not alter progesterone biosynthesis acutely (2-20 h) in swine or hamster ovarian cells. These observations suggest that there is an obligatory partitioning of some sterol into the ester pool in granulosa cells. In times of diminished availability of cholesterol, inhibition of the esterification pathway can make additional cholesterol available for use in steroid hormone biosynthesis. Thus, in the intact Graafian follicle, where LDL cholesterol delivery to granulosa cells and intracellular cholesteryl ester stores are limited, regulation of the ACAT reaction may significantly modulate rates of progesterone biosynthesis. The present results indicate that the use of a selective inhibitor of cholesterol esterification can permit one to probe the functional significance of the esterification reaction in steroidogenic cells.
AB - We have used a novel competitive inhibitor of acyl coenzyme A:cholesterol acyltransferase (ACAT), Sandoz compound 58-035 [3-(decyldimethyl-silyl)N-[2-(4-methylghenylph- phenylethyl propanamide], to assess the importance of the cholesterol esterification reaction in ovarian steroidogenesis. Compound 58-035 markedly (≥96%) inhibited ACAT activity of swine ovarian microsomes in a dose-dependent (0.1-3.5 µg/ml) fashion. In addition, treatment of cultured granulosa pells with this fatty acylamide effectively (≥98%) suppressed hormonally stimulated cholesterol esterification, as assessed by the incorporation of [3H]oleic acid into cholesteryl ester. Accordingly, we used this inhibitor to test the role of cholesterol esterification in ovarian cells. In cultures with limited or no serum supplementation, long term (2- to 6-day) treatment of granulosa cells with compound 58-035 significantly increased basal progesterone production and amplified by 2- to 10-fold the stimulatory actions of trophic hormones, such as estradiol, FSH, estradiol combined with FSH, or insulin. The amplifying effect of ACAT inhibition on hormone- stimulated progesterone production could be mimicked by providing exogenous cholesterol substrate in the form of low density lipoprotein (LDL). Cotreatment with compound 58-035 and LDL resulted in no further augmentation of steroidogenesis. In contrast to the facilitative effects of compound 58-035 in longer term cultures, this ACAT inhibitor did not alter progesterone biosynthesis acutely (2-20 h) in swine or hamster ovarian cells. These observations suggest that there is an obligatory partitioning of some sterol into the ester pool in granulosa cells. In times of diminished availability of cholesterol, inhibition of the esterification pathway can make additional cholesterol available for use in steroid hormone biosynthesis. Thus, in the intact Graafian follicle, where LDL cholesterol delivery to granulosa cells and intracellular cholesteryl ester stores are limited, regulation of the ACAT reaction may significantly modulate rates of progesterone biosynthesis. The present results indicate that the use of a selective inhibitor of cholesterol esterification can permit one to probe the functional significance of the esterification reaction in steroidogenic cells.
UR - http://www.scopus.com/inward/record.url?scp=0021994659&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0021994659&partnerID=8YFLogxK
U2 - 10.1210/endo-116-1-25
DO - 10.1210/endo-116-1-25
M3 - Article
C2 - 3917248
AN - SCOPUS:0021994659
SN - 0013-7227
VL - 116
SP - 25
EP - 30
JO - Endocrinology
JF - Endocrinology
IS - 1
ER -