Regulation Of Androgen Production Research Articles

FRI376 Regulation Of Theca Cell Function By Salt-Inducible Kinases

Abstract Disclosure: M. Rodriguez Esquivel: None. E. Hayes: None. O. Lakomy: None. M. Hassan: None. R. Filzen: None. C.O. Stocco: Grant Recipient; Self; NIH R01HD097202. The most common identifiable factors of female infertility are ovulatory disorders. Ovulation is the pinnacle of folliculogenesis, a process that requires an interplay between the oocyte, the granulosa cells, and the theca cells (TCs). TCs are the only source of ovarian androgens. Androgens play vital roles in female fertility acting as substrates for estrogen production in granulosa cells and directly regulating ovarian function via the activation of the androgen receptor. However, abnormally elevated androgen levels reduce fertility in humans and animals, suggesting that a delicate equilibrium exists between the beneficial and harmful effects of androgens in the ovary. Therefore, uncovering novel mechanisms regulating androgen synthesis in TCs is of great significance. The capacity of TCs to synthesize androgens relies on the expression of the rate-limiting enzyme CYP17A1, which converts progestogens into androgens, and its stimulation by the luteinizing hormone (LH). Previously, our group showed that salt-inducible kinases (SIKs) regulate granulosa cell steroidogenesis. Here, we investigated whether SIKs play any role in the regulation of androgen production in TCs. SIK2 and SIK3 were detected by IHC in the TCs of rat ovaries. Western blot confirmed this finding using isolated rat TCs. Next, rat TCs in culture were treated with LH in the presence or absence of HG, a highly specific SIK inhibitor. SIK inhibition enhanced the stimulatory effect of LH on Cyp17a1 mRNA expression. HG alone also increased Cyp17a1 expression to levels higher than those found in the presence of LH. Similarly, HG alone increased testosterone and potentiated LH stimulation of testosterone production. SIK inhibition also enhanced the stimulatory effect of LH on the expression of StAR and Cyp11a1. Concentration-response experiments for the SIK inhibitor in the presence or absence of LH show that SIK inhibition stimulates Cyp17a1 in a concentration-dependent manner from 0.1 to 1 µM. Of note, at 3 µM, HG was less effective in inducing Cyp17a1 than at 1 µM, suggesting that higher concentrations of HG may have alternative unknown effects. Activation of adenyl cyclase with forskolin or emulation of increased intracellular cAMP with dbcAMP stimulated Cyp17a1 an effect that was also enhanced by the inhibition of SIK. Since the main target of cAMP is PKA, we used lentivirus to express constitutively active PKA (caPKA). Overexpression of caPKA was sufficient to stimulate testosterone production, an effect that was significantly augmented by SIK inhibition, suggesting that SIKs regulate factors downstream of PKA. This evidence shows that TCs express SIKs and reveal novel roles for SIKs in the regulation of TC function and androgen production. This information could contribute to uncovering therapeutic targets to treat hyperandrogenic diseases such as PCOS. Presentation: Friday, June 16, 2023

Retinoic acid receptor beta and angiopoietin-like protein 1 are involved in the regulation of human androgen biosynthesis

Androgens are essential for sexual development and reproduction. However, androgen regulation in health and disease is poorly understood. We showed that human adrenocortical H295R cells grown under starvation conditions acquire a hyperandrogenic steroid profile with changes in steroid metabolizing enzymes HSD3B2 and CYP17A1 essential for androgen production. Here we studied the regulatory mechanisms underlying androgen production in starved H295R cells. Microarray expression profiling of normal versus starved H295R cells revealed fourteen differentially expressed genes; HSD3B2, HSD3B1, CYP21A2, RARB, ASS1, CFI, ASCL1 and ENC1 play a role in steroid and energy metabolism and ANGPTL1, PLK2, DUSP6, DUSP10 and FREM2 are involved in signal transduction. We discovered two new gene networks around RARB and ANGPTL1, and show how they regulate androgen biosynthesis. Transcription factor RARB stimulated the promoters of genes involved in androgen production (StAR, CYP17A1 and HSD3B2) and enhanced androstenedione production. For HSD3B2 regulation RARB worked in cooperation with Nur77. Secretory protein ANGPTL1 modulated CYP17A1 and DUSP6 expression by inducing ERK1/2 phosphorylation. By contrast, our studies revealed no evidence for hormones or cell cycle involvement in regulating androgen biosynthesis. In summary, these studies establish a firm role for RARB and ANGPTL1 in the regulation of androgen production in H295R cells.

Inhibition of LH-stimulated androgen production in rat immature Leydig cells: Effects on nuclear receptor steroidogenic factor 1 by FGF2

Both fibroblast growth factor 2 (FGF2) and luteinizing hormone (LH) have been reported to regulate androgen production in Leydig cells in progenitor Leydig cells. The objective of the present study is to examine the regulation of androgen production in rat immature Leydig cells (ILCs). ILCs were isolated from 35-day-old rat testes and cultured in DMEM/F12 medium with LH (1 ng/ml) or FGF2 (10 ng/ml). 5α-Androstane-3α, 17β-diol (3α-DIOL), the primary androgen in ILCs, and testosterone (T) were measured by Radioimmuno assay. The results showed the LH stimulated androgen production in ILCs, and FGF2 did not. However, FGF2 decreased the LH-stimulated androgen production. Real-time PCR and enzyme assay showed that FGF2 decreased levels of several steroidogenic enzymes, inhibited the expressions of steroidogenic acute regulatory (StAR) protein and steroidogenic factor 1 (Nr5a1) in LH-stimulated ILCs. FGF2-mediated inhibition of Nr5a1gene expression may be the mechanism through which FGF2 inhibits LH-stimulated androgen production.

Androgen production by monkey luteal cell subpopulations at different stages of the menstrual cycle.

Androgens produced by the primate corpus luteum (CL) serve as precursors for estrogen synthesis; moreover, detection of androgen receptors in luteal tissue suggests a regulatory role within the CL. To determine the cellular source(s) and agonist regulation of androgen production during the lifespan of the primate CL, luteal tissues were collected from rhesus monkeys in the early (days 3-5 post-LH surge), mid (days 7-8), mid-late (days 11-12), and late (days 14-15) luteal phase of the menstrual cycle. Collagenase-dispersed cells (i.e., mixed cells) were analyzed by flow cytometry based on light scatter properties and sorted into populations of small (< or = 15 microns) and large (> 20 microns) luteal cells. Cells (n = 4 animals/stage) were incubated in Ham's F-10 and 0.1% BSA for 3 h at 37 C with or without hCG (100 ng/mL), PGE2 (14 mumol/L), or dibutyryl cAMP (dbcAMP; 5 mmol/L), and androstenedione (A4) and testosterone were measured. Basal A4 production by large cells was markedly higher (P < 0.05) than that by small cells (e.g. mid-late luteal phase, 821 +/- 188 vs. 69 +/- 25 pg/mL.5 x 10(4) cells/3 h; mean +/- SEM), whereas that by mixed cells was intermediate (317 +/- 205 pg/mL). In the early luteal phase, hCG stimulated A4 synthesis by mixed (1.6-fold; P < 0.05) and large (3.1-fold; P < 0.05) luteal cells, but not by small cells (1.3-fold). By the mid-late luteal phase, hCG did not increase A4 production by any cell type, although hCG responsiveness returned to large cells (2.0-fold increase; P < 0.05) by the late luteal phase. PGE2 responsiveness by cell types was similar to that of hCG, except large cell responsiveness did not return in the late luteal phase. In all cell types, dbcAMP stimulated the largest increase in A4 levels; in the mid-late luteal phase, small and large cells responded to dbcAMP with 8.2- and 3.0-fold increases (P < 0.05) in A4 production, respectively. When luteal cells were incubated with the steroidogenic substrates, 17 alpha-hydroxyprogesterone or 17 alpha-hydroxypregnenolone (1 mumol/L), large cells produced much more (P < 0.05) A4, testosterone, estrone, and estradiol than small cells. Both substrates elicited similar patterns of androgen production, with A4 synthesis predominant in all luteal cell types. Thus, cell subpopulations in the primate CL can be distinguished by their ability to produce androgen and estrogen. Changes in agonist-responsive androgen production may influence the local steroid milieu and function of the CL during the menstrual cycle.

Hypersecretion of androstenedione by isolated thecal cells from polycystic ovaries.

The aim of this study was to examine the hypothesis that hypersecretion of ovarian androgens in polycystic ovary syndrome results from an intrinsic abnormality of androgen biosynthesis by thecal cells. Steroid accumulation by human thecal cells from normal and polycystic ovaries (PCO-theca) was examined under basal and LH-stimulated conditions. A method for dispersing and culturing human thecal cells as primary monolayers in serum-free medium was developed. LH increased androstenedione (A), progesterone (P), 17 alpha-hydroxyprogesterone, dehydroepiandrosterone, and estradiol accumulation in the overlying medium in a dose-dependent manner at a maximum effective dose of 2.5 ng/mL. The principal variables affecting the magnitude of steroid accumulation were plating density, duration of incubation, and follicle size. Using only theca from follicles less than 10 mm and keeping plating density constant, 48-h steroid production by theca from five normal ovaries was compared to that from nine polycystic ovaries isolated from both anovulatory and ovulatory women. There was a significant increase in both basal (median, 32.1 pmol/1000 cells.48 h; range, 18.7-250) and LH-stimulated (56 pmol/1000 cells; range, 40.7-406) A accumulation by PCO-theca compared to basal (1.7 pmol/1000 cells; range, 1.1-4.3) and LH-stimulated (2.8 pmol/1000 cells; range, 2.0-8.1) A accumulation by normal theca, with no overlap in values between the two. Although P production was also increased in the PCO-theca, the A to P ratios under both basal and LH-stimulated conditions were significantly higher in the PCO-theca [A/P ratio normal; PCO basal, 0.1 and 0.53 (P < 0.01); LH-stimulated, 0.04 and 0.65 (P < 0.001)], suggesting increased conversion of P to A. The steroid response to LH was similar in both groups. This is the first report of a difference in thecal androgen production between normal and polycystic ovaries and supports the hypothesis that there is a primary abnormality in the regulation of androgen production in PCOS.

Regulation of androgen production in cultured human thecal cells by insulin-like growth factor I and insulin

To investigate if human thecal cells contain messenger ribonucleic acid (RNA) encoding insulin-like growth factor I (IGF-I) and insulin receptors and if IGF-I and insulin could stimulate androgen production in thecal cells. Poly-adenine+ RNA was extracted from fresh thecal tissue, and the expression of the genes encoding insulin and IGF-I receptors were analyzed. Isolated thecal cells were cultured 4 to 6 days with and without hormones. Procedures were performed in a university laboratory. Eight women in the follicular phase of natural cycles were undergoing gynecological laparotomy for reasons unrelated to ovarian pathology. The leading follicle(s) was excised, and dispersed cells of the theca interna layer were isolated through combined mechanical and enzymatic techniques. Luteinizing hormone (LH), IGF-I, and insulin were added to the cell cultures. The expression of IGF-I receptor and insulin receptor transcripts were analyzed by Northern blot. Medium levels of androstenedione and testosterone were measured by radioimmunoassay. In the separated thecal tissue both IGF-I receptor and insulin-receptor transcripts were detected. Insulin-like growth factor I and insulin potentiated LH-induced androgen secretion while having less pronounced effects on basal androgen production. The present study demonstrates that both insulin and IGF-I receptor genes are expressed and that insulin and IGF-I can stimulate steroid production in human thecal cells. The study provides further support for the hypothesis that IGF-I and insulin may be involved both in physiological regulation of ovarian function as well as in its pathophysiology.

An Autoregulatory Process for Androgen Production in Rat Thecal-Interstitial Cells1

The regulation of androgen production by thecal-interstitial cells (TIC) of the mammalian ovary is a complex process. Although androgen production is primarily controlled by LH, a variety of factors have been demonstrated to alter LH-stimulated androgen production. It is uncertain, however, if an androgen-mediated autoregulatory process for androgen production exists in TIC. To determine the existence of this phenomenon, TIC obtained from ovaries of immature hypophysectomized rats were enriched by Percoll density gradient centrifugation. When TIC (20,000 viable cells/0.2 ml/well) were cultured for 48 h in the presence of a maximal concentration of hCG (0.2 ng/ml), androsterone production was increased 26-fold versus control levels. Treatment with increasing concentrations (5-1000 nM) of the synthetic androgen 17 beta-hydroxy-7 alpha,17 alpha-dimethyl-4-estren-3-one (mibolerone) inhibited hCG-stimulated androsterone production by an average of 32% at every dose tested. Mibolerone (100 nM) alone was without effect on basal levels of androgens. The addition of insulin (100 ng/ml) or insulin-like growth factor I (100 ng/ml) to TIC cultures did not alter the basal accumulation of androsterone but significantly augmented hCG-induced androgen production by 2- and 3-fold, respectively, versus controls. Concomitant treatment with mibolerone (100 nM) decreased the synergistic action of insulin or IGF-I on hCG-stimulated androsterone synthesis by 46% and 40%, respectively. To elucidate the mechanism(s) of action of mibolerone, we investigated the effects on 8-bromo-cAMP-stimulated androgen production. At a dose of 0.1 mM 8-bromo-cAMP, androsterone production was maximally stimulated to levels observed with 0.2 ng/ml hCG. In the presence of mibolerone (100 nM), cAMP-induced androsterone synthesis was inhibited by 41%. This result suggested that mibolerone was acting at a site distal to cAMP formation. Additional evidence revealed that through the use of the combination of cAMP analogs, N6-monobutyryl-cAMP (50 microM) and 8-bromo-cAMP (75 microM)--which are known activators of the cAMP-dependent protein kinase isoenzymes PKA I and II--androsterone synthesis was increased by 130-fold over basal levels. Treatment with mibolerone (100 nM), however, reduced this cAMP-stimulated androgen synthesis by 51%. Therefore, the results demonstrate the existence of an autoregulatory process for androgen production in TIC, which may be important in limiting the overproduction of androgens.

Catecholamines inhibit steroidogenesis by cultured porcine thecal cells

The ovaries of many species contain catecholamines and β-adrenergic receptors. The present studies were done to determine if catecholamines play a role in the regulation of androgen production by porcine theca cells. Basal and luteinizing hormone (LH)-stimulated androstenedione production was significantly inhibited by noradrenaline and isoproterenol. The inhibitory effects were dose-dependent and were enhanced when the cultures contained the carboxy- O-methyl transferase inhibitor, U-0521. The inhibitory effect of isoproterenol was reversed by the β-adrenergic antagonist, metoprolol. Isoproterenol caused a generalized inhibition of LH-stimulated steroidogenesis, decreasing the accumulation of pregnenolone, progesterone, androstenedione and estradiol in the culture medium. These studies suggest that catecholamines may be important regulators of thecal androgen production.

Mesenchymal-epithelial cell interactions in the ovary: estrogen-induced theca cell steroidogenesis

The role of mesenchymal-epithelial cell interactions in the control of ovarian physiology was investigated Theca cells are the mesenchymal (i.e. stromal) like cells that surround the ovarian follicle and produce androgen in response to the gonadotropin luteinizing hormone (LH). Granulosa cells are the epithelial-like cells that form the follicle, support the developing oocyte, and utilize androgens produced by theca cells as a substrate for the production of estrogen Observations presented indicate that estrogen produced by granulosa cells dramatically stimulates androgen production by theca cells Estrogen was found to have greater stimulatory effect on theca cell androgen production than gonadotropin, and a combination of estrogen and gonadotropin results in a greater than additive response of the two hormones. Regulation of androgen production by estrogen provides a local feedback loop in the follicle that will significantly influence ovarian steroidogenesis. This steroid-mediated theca-granulosa cell interaction provides evidence for the importance of mesenchymal (i.e. stromal)-epithelial cell interactions in adult tissues and implies that epithelial cells can produce paracrine factors that modulate mesenchymal cell function and differentiation The theca cell-granulosa cell interaction identified is postulated to be a critical mesenchymal-epithelial cell interaction for the control of ovarian physiology and the endocrine status of the female.

Regulation of androgen production by frog ( Rana esculenta) testis: An in vitro study on the effects exerted by estradiol, 5α-dihydrotestosterone, testosterone, melatonin, and serotonin

The possible role of estradiol-17β (E 2), testosterone (T), 5α-dihydrotestosterone (DHT), melatonin, and serotonin on the regulation of androgen (A) production by the frog, Rana esculenta, testes was studied in vitro, E 2 (10 −6 M) inhibited A production whether alone or in combination with oLH (20 μg) after 6 hr incubation. After 24 hr incubation, A production was reduced by E 2 concentration of around 10 −6 and 10 −9 M. Melatonin and serotonin did not induce any change whichever experimental condition was used. Preincubation for 6 hr with 10 −6 M T or DHT enhanced the oLH-stimulated A production after 18 hr incubation. These data suggest that steroids may regulate their intratesticular levels without passing into the blood stream.