scholarly journals Changes in mRNAs encoding steroidogenic acute regulatory protein, steroidogenic enzymes and receptors for gonadotropins during spermatogenesis in rainbow trout testes

2006 ◽  
Vol 189 (3) ◽  
pp. 541-554 ◽  
Author(s):  
M Kusakabe ◽  
I Nakamura ◽  
J Evans ◽  
P Swanson ◽  
G Young
Keyword(s):  
Cytochrome P450 ◽  
Rainbow Trout ◽  
Reproductive Cycle ◽  
Regulatory Protein ◽  
Hydroxysteroid Dehydrogenase ◽  
Steroidogenic Acute Regulatory Protein ◽  
Fsh Receptor ◽  
Steroidogenic Enzyme ◽  
Lh Receptor ◽  
Steroidogenic Acute Regulatory

In vertebrates, sperm development and maturation are directly regulated by gonadal steroid hormone secretion. The relationships among the expression of genes encoding steroidogenic proteins and receptors for gonadotropins, and testicular steroid production have not yet been comprehensively determined in male teleosts. In this study, the changes in levels of mRNAs encoding follicle-stimulating hormone (FSH) receptor, luteinizing hormone (LH) receptor, steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage, 3β-hydroxysteroid dehydrogenase/Δ5–4-isomerase, cytochrome P450 17α-hydroxylase/17,20-lyase, cytochrome P450 11β-hydroxylase, 11β-hydroxysteroid dehydrogenase and 20β-hydroxysteroid dehydrogenase were determined by real-time, quantitative PCR assays and related to changes in serum steroid levels throughout the reproductive cycle in male rainbow trout. Serum 11-ketotestosterone and 17α,20β-dihydroxy-4-pregnen-3-one levels were measured by RIA. Although the pattern of change in the mRNA levels for the enzymes was variable, the increases in steroidogenic enzyme mRNAs started prior to a significant increase of serum steroid levels. The patterns of transcript levels of FSH and LH receptors suggest that changes in StAR and steroidogenic enzyme transcripts are largely mediated by the FSH receptor during early and mid-spermatogenesis and by the LH receptor during late spermatogenesis and spermiation. Levels of StAR (10-fold) and P450 17α-hydroxylase/17,20-lyase (sevenfold) transcripts changed with the greatest magnitude and were closely related to the changes in serum steroids, suggesting that changes in StAR and P450 17α-hydroxylase/17,20-lyase abundance are likely to be the major influences on overall steroidogenic output during the reproductive cycle in male rainbow trout.

scholarly journals Luteinizing Hormone/Human Chorionic Gonadotropin-Mediated Activation of mTORC1 Signaling Is Required for Androgen Synthesis by Theca-Interstitial Cells

2012 ◽  
Vol 26 (10) ◽  
pp. 1732-1742 ◽  
Author(s):  
Murugesan Palaniappan ◽  
K. M. J. Menon
Keyword(s):  
Chorionic Gonadotropin ◽  
Regulatory Protein ◽  
Steroidogenic Acute Regulatory Protein ◽  
Steroidogenic Enzymes ◽  
Steroidogenic Enzyme ◽  
S6 Kinase ◽  
Ribosomal Protein S6 ◽  
Mtorc1 Signaling ◽  
Steroidogenic Acute Regulatory ◽  
I Cells

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.

scholarly journals Regulation by Adrenocorticotropin (ACTH), Angiotensin II, Transforming Growth Factor-β, and Insulin-Like Growth Factor I of Bovine Adrenal Cell Steroidogenic Capacity and Expression of ACTH Receptor, Steroidogenic Acute Regulatory Protein, Cytochrome P450c17, and 3β-Hydroxysteroid Dehydrogenase*

Endocrinology ◽  
2000 ◽  
Vol 141 (5) ◽  
pp. 1599-1607 ◽  
Author(s):  
Christine Le Roy ◽  
J. Yuan Li ◽  
Douglas M. Stocco ◽  
Dominique Langlois ◽  
José M. Saez
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Regulatory Protein ◽  
Hydroxysteroid Dehydrogenase ◽  
Steroidogenic Acute Regulatory Protein ◽  
Mrna Levels ◽  
Factor I ◽  
Acth Receptor ◽  
Igf I ◽  
Steroidogenic Acute Regulatory

Abstract The purpose of this study was to evaluate the time-course effect of a 36-h treatment with ACTH (10−8m), transforming growth factor-β1 (TGFβ1; 10−10m), angiotensin II (AngII; 10−7m), and insulin-like growth factor I (IGF-I; 10−8m) on the steroidogenic capacity of bovine adrenocortical cells (BAC) and on messenger RNA (mRNA) levels of ACTH receptor, cytochrome P450c17, 3β-hydroxysteroid dehydrogenase (3βHSD), steroidogenic acute regulatory protein (StAR), and StAR protein. ACTH and IGF-I enhanced, in a time-dependent manner, the acute 2-h ACTH-induced cortisol production, whereas TGFβ1 and AngII markedly reduced it. ACTH, IGF-I, and AngII increased ACTH receptor mRNA, but the opposite was observed after TGFβ1 treatment. ACTH and IGF-I increased P450c17 and 3βHSD mRNAs, whereas AngII and TGFβ1 had the opposite effects. However, the effects of the four peptides on ACTH-induced cortisol production appeared before any significant alterations of the mRNA levels occurred. The most marked and rapid effect of the four peptides was on StAR mRNA. The stimulatory effect of ACTH was seen within 1.5 h, peaked at 4–6 h, and declined thereafter, but at the end of the 36-h pretreatment, the levels of StAR mRNA and protein were higher than those in control cells. IGF-I also enhanced StAR mRNA levels within 1.5 h, and these levels remained fairly constant. The effects of AngII on StAR mRNA expression were biphasic, with a peak within 1.5–3 h, followed by a rapid decline to almost undetectable levels of both mRNA and protein. TGFβ1 had no significant effect during the first 3 h, but thereafter StAR mRNA declined, and at the end of the experiment the StAR mRNA and protein were almost undetectable. Similar results were observed when cells were treated with ACTH plus TGFβ1. A 2-h acute ACTH stimulation at the end of the 36-h pretreatment caused a higher increase in StAR mRNA and protein in ACTH- or IGF-I-pretreated cells than in control cells, which, in turn, had higher levels than cells pretreated with TGFβ1, ACTH plus TGFβ1, or AngII. These results and the fact that the stimulatory (IGF-I) or inhibitory (AngII and TGFβ1) effects on ACTH-induced cortisol production were more pronounced than those on the ability of cells to transform pregnenolone into cortisol strongly suggest that regulation of StAR expression is one of the main factors, but not the only one, involved in the positive (IGF-I) or negative (TGFβ1 and AngII) regulation of BAC for ACTH steroidogenic responsiveness. A high correlation between steady state mRNA level and acute ACTH-induced cortisol production favors this conclusion.

Influence of season and low-level oestradiol immunoneutralization on episodic LH and testosterone secretion and testicular steroidogenic enzymes and steroidogenic acute regulatory protein in the adult ram

Reproduction ◽  
2000 ◽  
pp. 251-262 ◽  
Author(s):  
CA Price ◽  
GM Cooke ◽  
LM Sanford
Keyword(s):  
Cytochrome P450 ◽  
Breeding Season ◽  
Regulatory Protein ◽  
Density Lipoprotein ◽  
Pulse Frequency ◽  
Steroidogenic Acute Regulatory Protein ◽  
Blood Concentrations ◽  
Testosterone Secretion ◽  
Testosterone Biosynthesis ◽  
Steroidogenic Acute Regulatory

The regulation of LH-dependent and -independent increases in testosterone secretion by key proteins in the testes of adult rams was investigated. Serial blood samples were collected from groups of four control and passively immunized (oestradiol antiserum for 3 weeks) rams and the animals were gonadectomized in either the non-breeding season (April) or the breeding season (September). LH pulse frequency and basal (interpulse) concentrations were several times greater (P < 0.01) in the breeding season than in the non-breeding season. Neither of these parameters nor LH pulse amplitude were affected by oestradiol immunization. Parameters of testosterone episodic secretion and response to an injection (i.v.) of 15 micrograms NIH-LH-S25 were also greater (P < 0.05) in the breeding season and, with the exception of pulse frequency, in immunized rams versus controls. Substrate utilization established that testosterone biosynthesis was predominantly via the 5-ene pathway. Increases in blood testosterone concentration in the breeding season were associated with a fivefold higher (P < 0.01) activity of cytochrome P450 17alpha-hydroxylase/C-17,20 lyase (P450(17alpha)) and a 65% higher (P < 0.05) relative amount of mRNA for cytochrome P450 cholesterol side-chain cleavage enzyme complex (P450scc) in the testis. Of the steroidogenic enzyme activities examined, only that for 17beta-hydroxysteroid dehydrogenase (17beta-HSD) tended to be increased by oestradiol immunization. Blood concentrations of cholesterol lipoproteins and expression of the testicular low density lipoprotein receptor were not affected by season or immunization. The amount of steroidogenic acute regulatory protein (StAR) mRNA was 65% higher (P < 0.01) in the breeding season and 20% higher (P < 0.01) in immunized rams versus controls. These results indicate that greater LH stimulation may increase testosterone biosynthesis in the breeding season by increasing StAR mRNA (and presumably delivery of cholesterol to P450scc) and the activity of P450(17alpha), and possibly that of P450scc (activity not measured). More moderate increases in StAR mRNA and 17beta-HSD activity may explain, in part, the increases in testosterone secretion with oestradiol immunization.

scholarly journals Cyclooxygenase-2 and Prostaglandin F2α in Syrian Hamster Leydig Cells: Inhibitory Role on Luteinizing Hormone/Human Chorionic Gonadotropin-Stimulated Testosterone Production

Endocrinology ◽  
2006 ◽  
Vol 147 (9) ◽  
pp. 4476-4485 ◽  
Author(s):  
Mónica B. Frungieri ◽  
Silvia I. Gonzalez-Calvar ◽  
Fernanda Parborell ◽  
Martin Albrecht ◽  
Artur Mayerhofer ◽  
...  
Keyword(s):  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Syrian Hamster ◽  
Leydig Cells ◽  
Regulatory Protein ◽  
Hydroxysteroid Dehydrogenase ◽  
Steroidogenic Acute Regulatory Protein ◽  
Testosterone Production ◽  
Cox 2 ◽  
Steroidogenic Acute Regulatory

We have previously found that cyclooxygenase-2 (COX-2), a key enzyme in the biosynthesis of prostaglandins (PGs), is present in the testicular interstitial cells of infertile men, whereas it is absent in human testes with no evident morphological changes or abnormalities. To find an animal model for further investigating COX-2 and its role in testicular steroidogenesis, we screened testes from adult species ranging from mice to monkeys. By using immunohistochemical assays, we found COX-2 expression only in Leydig cells of the reproductively active (peripubertal, pubertal, and adult) seasonal breeder Syrian hamster. COX-2 expression in hamster Leydig cells was confirmed by RT-PCR. In contrast, COX-1 expression was not detected in hamster testes. Because COX-2 expression implies PG synthesis, we investigated the effect of various PGs on testosterone production and found that PGF2α stood out because it significantly reduced human chorionic gonadotropin-stimulated testosterone release from isolated hamster Leydig cells in a dose-dependent manner. This mechanism involves a decreased expression of testicular steroidogenic acute regulatory protein and 17β-hydroxysteroid dehydrogenase. Testicular concentration and content of PGF2α in reproductively active hamsters as well as production of PGF2α from isolated hamster Leydig cells were also determined. Moreover, PGF2α receptors were localized in Leydig cells of hamsters and testicular biopsies from patients with Sertoli cell only and germ arrest syndromes. Thus, in this study, we described a COX-2-initiated pathway that via PGF2α production, PGF2α receptors, steroidogenic acute regulatory protein, and 17β-hydroxysteroid dehydrogenase represents a physiological local inhibitory system of human chorionic gonadotropin-stimulated testosterone production in the Syrian hamster testes.

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