Abstract
Estradiol (E2) production by human luteinized granulosa cells (hLGC) is inhibited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The molecular target of TCDD toxicity has not been identified. The decrease in E2 is ameliorated by androgen substrate addition and is not associated with changes in aromatase cytochrome P450 (P450arom) activity or protein expression. An antihuman 17α-hydroxylase/17,20-lyase cytochrome P450 (P450c17) antisera and a direct radiometric assay of 17,20-lyase activity were used to test the hypothesis that TCDD targets P450c17, thereby decreasing substrate availability for E2 synthesis by hLGC. P450c17 expression and 17,20-lyase activity were detected in hLGC with high levels of E2 secretion. Western immunoblot analysis demonstrated that TCDD treatment of hLGC decreased the expression of P450c17 by as much 50% (P < 0.05). TCDD exposure induced a 65% decrease in 17,20-lyase activity (P < 0.05), but no changes were seen in P450arom or in nicotinamide adenine dinucleotide phosphate (reduced)-cytochrome P450 oxido-reductase (reductase). Furthermore, the decreases in P450c17 and 17,20-lyase were proportional to the inhibition of E2 secretion. We conclude that the molecular target for endocrine disruption of hLGC by TCDD is P450c17, specifically decreasing the supply of androgens for E2 synthesis, and that it does not involve either P450arom or the redox partner protein reductase.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 467-473 |
| Number of pages | 7 |
| Journal | Endocrinology |
| Volume | 144 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2003 |
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ASJC Scopus subject areas
- Endocrinology
- Endocrinology, Diabetes and Metabolism
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Molecular target of endocrine disruption in human luteinizing granulosa cells by 2,3,7,8-tetrachlorodibenzo-p-dioxin : Inhibition of estradiol secretion due to decreased 17α-hydroxylase/17,20-lyase cytochrome p450 expression. / Morán, F. M.; Vandevoort, C. A.; Overstreet, J. W.; Lasley, B. L.; Conley, Alan J.
In: Endocrinology, Vol. 144, No. 2, 01.02.2003, p. 467-473.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Molecular target of endocrine disruption in human luteinizing granulosa cells by 2,3,7,8-tetrachlorodibenzo-p-dioxin
T2 - Inhibition of estradiol secretion due to decreased 17α-hydroxylase/17,20-lyase cytochrome p450 expression
AU - Morán, F. M.
AU - Vandevoort, C. A.
AU - Overstreet, J. W.
AU - Lasley, B. L.
AU - Conley, Alan J
PY - 2003/2/1
Y1 - 2003/2/1
N2 - Estradiol (E2) production by human luteinized granulosa cells (hLGC) is inhibited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The molecular target of TCDD toxicity has not been identified. The decrease in E2 is ameliorated by androgen substrate addition and is not associated with changes in aromatase cytochrome P450 (P450arom) activity or protein expression. An antihuman 17α-hydroxylase/17,20-lyase cytochrome P450 (P450c17) antisera and a direct radiometric assay of 17,20-lyase activity were used to test the hypothesis that TCDD targets P450c17, thereby decreasing substrate availability for E2 synthesis by hLGC. P450c17 expression and 17,20-lyase activity were detected in hLGC with high levels of E2 secretion. Western immunoblot analysis demonstrated that TCDD treatment of hLGC decreased the expression of P450c17 by as much 50% (P < 0.05). TCDD exposure induced a 65% decrease in 17,20-lyase activity (P < 0.05), but no changes were seen in P450arom or in nicotinamide adenine dinucleotide phosphate (reduced)-cytochrome P450 oxido-reductase (reductase). Furthermore, the decreases in P450c17 and 17,20-lyase were proportional to the inhibition of E2 secretion. We conclude that the molecular target for endocrine disruption of hLGC by TCDD is P450c17, specifically decreasing the supply of androgens for E2 synthesis, and that it does not involve either P450arom or the redox partner protein reductase.
AB - Estradiol (E2) production by human luteinized granulosa cells (hLGC) is inhibited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The molecular target of TCDD toxicity has not been identified. The decrease in E2 is ameliorated by androgen substrate addition and is not associated with changes in aromatase cytochrome P450 (P450arom) activity or protein expression. An antihuman 17α-hydroxylase/17,20-lyase cytochrome P450 (P450c17) antisera and a direct radiometric assay of 17,20-lyase activity were used to test the hypothesis that TCDD targets P450c17, thereby decreasing substrate availability for E2 synthesis by hLGC. P450c17 expression and 17,20-lyase activity were detected in hLGC with high levels of E2 secretion. Western immunoblot analysis demonstrated that TCDD treatment of hLGC decreased the expression of P450c17 by as much 50% (P < 0.05). TCDD exposure induced a 65% decrease in 17,20-lyase activity (P < 0.05), but no changes were seen in P450arom or in nicotinamide adenine dinucleotide phosphate (reduced)-cytochrome P450 oxido-reductase (reductase). Furthermore, the decreases in P450c17 and 17,20-lyase were proportional to the inhibition of E2 secretion. We conclude that the molecular target for endocrine disruption of hLGC by TCDD is P450c17, specifically decreasing the supply of androgens for E2 synthesis, and that it does not involve either P450arom or the redox partner protein reductase.
UR - http://www.scopus.com/inward/record.url?scp=0037318493&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037318493&partnerID=8YFLogxK
U2 - 10.1210/en.2002-220813
DO - 10.1210/en.2002-220813
M3 - Article
C2 - 12538606
AN - SCOPUS:0037318493
VL - 144
SP - 467
EP - 473
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 2
ER -