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Luteinizing hormone/human chorionic gonadotropin-mediated activation of mTORC1 signaling is required for androgen synthesis by theca-interstitial cells.
- Source :
-
Molecular endocrinology (Baltimore, Md.) [Mol Endocrinol] 2012 Oct; Vol. 26 (10), pp. 1732-42. Date of Electronic Publication: 2012 Jul 24. - Publication Year :
- 2012
-
Abstract
- LH triggers the biosynthesis of androgens in the theca-interstitial (T-I) cells of ovary through the activation of a cAMP-dependent pathway. We have previously shown that LH/human chorionic gonadotropin (hCG) activates mammalian target of rapamycin complex 1 (mTORC1) signaling network, leading to cell proliferation. In the present study, we provide evidence that the LH/hCG-mediated activation of the mTORC1 signaling cascade is involved in the regulation of steroidogenic enzymes in androgen biosynthesis. Treatment with LH/hCG increased the expression of downstream targets of mTORC1, ribosomal protein S6 kinase 1, and eukaryotic initiation factor 4E as well as steroidogenic enzymes. LH/hCG-mediated stimulation of the steroidogenic enzyme mRNA was blocked by the mTORC1 inhibitor, rapamycin. This inhibitory effect was selective because rapamycin failed to block hCG-mediated increase in the expression of Star mRNA levels. Furthermore, pharmacological targeting of mTORC1 with rapamycin also blocked LH/hCG- or forskolin-induced expression of cAMP response element-binding protein (CREB) and steroidogenic enzymes (P450 side-chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase type 1, and 17α-hydroxylase/17,20 lyase) but produced no effect on steroidogenic acute regulatory protein levels. These results were further confirmed by demonstrating that the knockdown of mTOR using small interfering RNA selectively abrogated the LH/hCG-induced increase in steroidogenic enzyme expression, without affecting steroidogenic acute regulatory protein expression. LH/hCG-stimulated androgen production was also blocked by rapamycin. Furthermore, the pharmacological inhibition of mTORC1 or ribosomal protein S6 kinase 1 signaling prevented the LH/hCG-induced phosphorylation of CREB. Chromatin immunoprecipitation assays revealed the association of CREB with the proximal promoter of the Cyp17a1 gene in response to hCG, and this association was reduced by rapamycin treatment. Taken together, our findings show for the first time that LH/hCG-mediated activation of androgen biosynthesis is regulated by the mTORC1 signaling pathway in T-I cells.
- Subjects :
- Androstenedione biosynthesis
Animals
Cells, Cultured
Cholesterol Side-Chain Cleavage Enzyme genetics
Cholesterol Side-Chain Cleavage Enzyme metabolism
Chorionic Gonadotropin pharmacology
Colforsin pharmacology
Cyclic AMP Response Element-Binding Protein metabolism
Enzyme Induction
Eukaryotic Initiation Factor-4E genetics
Eukaryotic Initiation Factor-4E metabolism
Female
Gene Knockdown Techniques
Luteinizing Hormone pharmacology
Mechanistic Target of Rapamycin Complex 1
Multiprotein Complexes
Phosphoproteins metabolism
Phosphorylation
Protein Processing, Post-Translational
Proteins antagonists & inhibitors
RNA Interference
Rats
Rats, Sprague-Dawley
Ribosomal Protein S6 Kinases genetics
Ribosomal Protein S6 Kinases metabolism
Signal Transduction
Sirolimus pharmacology
Steroid 17-alpha-Hydroxylase genetics
Steroid 17-alpha-Hydroxylase metabolism
TOR Serine-Threonine Kinases genetics
TOR Serine-Threonine Kinases metabolism
Androgens biosynthesis
Chorionic Gonadotropin physiology
Luteinizing Hormone physiology
Proteins metabolism
Theca Cells metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1944-9917
- Volume :
- 26
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- Molecular endocrinology (Baltimore, Md.)
- Publication Type :
- Academic Journal
- Accession number :
- 22827930
- Full Text :
- https://doi.org/10.1210/me.2012-1106