Inverse relationship between the expression of messenger ribonucleic acid for peroxisome proliferator-activated receptor gamma and P450 side chain cleavage in the rat ovary

Messenger RNA for peroxisome proliferator-activated receptor gamma (PPARgamma) has been found in granulosa cells, and its expression decreases after the LH surge. We determined which developmental stage of ovarian follicle expresses mRNA for PPARgamma and evaluated the impact of PPARgamma agonists on steroidogenesis. Ovaries were collected from immature eCG/hCG-treated rats at 0 (no eCG), 24, and 48 h post-eCG and 4 and 24 h post-hCG. Ovarian tissue was serially sectioned and processed for in situ hybridization to localize mRNA corresponding to PPARgamma, aromatase, and the LH receptor, and P450 side chain cleavage (P450SCC) and to determine whether apoptotic cells were present. During follicular development, there was no correlation between the expression of mRNAs for PPARgamma and aromatase or the presence of apoptotic cells, but a general inverse correlation was observed between the expression of PPARgamma mRNA and LH receptor mRNA. At 4 h post-hCG, follicles expressing P450SCC mRNA had lost expression of PPARgamma mRNA. This inverse pattern of expression between PPARgamma and P450SCC mRNAs was also observed 24 h post-hCG, with developing luteal tissue expressing high levels of P450SCC mRNA but little or no PPARgamma mRNA. To determine the impact of PPARgamma on steroidogenesis, granulosa cells were collected from ovaries 24 h post-eCG and cultured alone, with FSH alone, or with FSH in combination with the PPARgamma agonists ciglitazone or 15-deoxy-delta 12,14-prostaglandin J2 (PGJ2). Treatment of granulosa cells with PGJ2 stimulated basal progesterone secretion, whereas ciglitazone or PGJ2 had no significant effect on FSH-stimulated steroid production. These findings suggest that 1) PPARgamma may regulate genes involved with follicular differentiation and 2) the decline in PPARgamma in response to LH is important for ovulation and/or luteinization.

Ff1b is required for the development of steroidogenic component of the zebrafish interrenal organ

The zebrafish ftz-f1 gene, ff1b, is activated in two cell clusters lateral to the midline in the trunk during late embryogenesis. These cell clusters coalesce to form a discrete organ at around 30 hpf, which then begins to acquire a steroidogenic identity as evidenced by the expression of the steroidogenic enzyme genes, cyp11a and 3beta-hsd. The migration of the cell clusters to the midline is impaired in zebrafish midline signaling mutants. Knockdown of Ff1b activity by antisense ff1b morpholino oligonucleotide (ff1bMO) leads to phenotypes that are consistent with impaired osmoregulation. Injection of ff1bMO was also shown to downregulate the expression of cyp11a and 3beta-hsd. Histological comparison of wild-type and ff1b morphants at various embryonic and juvenile stages revealed the absence of interrenal tissue development in ff1b morphants. The morphological defects of ff1b morphants could be mimicked by treatment with aminoglutethimide, an inhibitor of de novo steroid synthesis. Based on these data, we propose that ff1b is required for the development of the steroidogenic tissue of the interrenal organ.

The molecular phenotype of polycystic ovary syndrome (PCOS) theca cells and new candidate PCOS genes defined by microarray analysis

Polycystic ovary syndrome (PCOS) affects 5% of reproductive aged women and is the leading cause of anovulatory infertility. A hallmark of PCOS is excessive theca cell androgen secretion, which is directly linked to the symptoms of PCOS. Our previous studies demonstrated that theca cells from PCOS ovaries maintained in long term culture persistently secrete significantly greater amounts of androgens than normal theca cells, suggesting an intrinsic abnormality. Furthermore, previous studies suggested that ovarian hyperandrogenemia is inherited as an autosomal dominant trait. However, the genes responsible for ovarian hyperandrogenemia of PCOS have not been identified. In this present study, we carried out microarray analysis to define the gene networks involved in excess androgen synthesis by the PCOS theca cells in order to identify candidate PCOS genes. Our analysis revealed that PCOS theca cells have a gene expression profile that is distinct from normal theca cells. Included in the cohort of genes with increased mRNA abundance in PCOS theca cells were aldehyde dehydrogenase 6 and retinol dehydrogenase 2, which play a role in all-trans-retinoic acid biosynthesis and the transcription factor GATA6. We demonstrated that retinoic acid and GATA6 increased the expression of 17alpha-hydroxylase, providing a functional link between altered gene expression and intrinsic abnormalities in PCOS theca cells. Thus, our analyses have 1) defined a stable molecular phenotype of PCOS theca cells, 2) suggested new mechanisms for excess androgen synthesis by PCOS theca cells, and 3) identified new candidate genes that may be involved in the genetic etiology of PCOS.

Expression of 3beta-hydroxysteroid dehydrogenase and P450 side chain cleavage enzyme in the human uterine endometrium

The enzyme complex 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4-isomerase (3beta-HSD) is involved in the biosynthesis of all classes of active steroids. The expression of 3b-HSD in human uterine endometrium during the menstrual cycle and decidua was examined in an effort to understand its role during ova implantation. 3beta-HSD was weakly expressed in the glandular epithelium of the proliferative phase and moderately expressed in the glandular epithelium of secretory phase of the endometrium. In the decidua of the ectopic pregnancy, 3beta-HSD was strongly expressed. The human uterine endometrial 3beta-HSD was identified as being the same type as the placental 3beta-HSD by RT-PCR and sequence analysis. In addition to the expression of 3beta-HSD, P450scc was expressed in the decidua of the ectopic pregnancy. These results suggest that pregnenolone might be synthesized from cholesterol by P450scc de novo and then, it is converted to progesterone by 3beta-HSD in the uterine endometrium. The data implies that the endometrial 3beta-HSD can use not only the out-coming pregnenolone from the adrenal gland but also the self- made pregnenolone to produce progesterone. The de novo synthesis of progesterone in the endometrium might be a crucial factor for implantation and maintenance of pregnancy.

ACTH modulation of transcription factors responsible for steroid hydroxylase gene expression in the adrenal cortex

Steroid hormone biosynthesis in the adrenal cortex and gonads involves the coordinated transcription of the genes encoding the steroid hydroxylases, 3beta-hydroxysteroid dehydrogenase (3betaHSD), the steroidogenic acute regulatory protein (StAR), and adrenodoxin (Adx). Transcriptional regulation of steroidogenic genes is multifactorial, entailing developmental, tissue-specific, constitutive, and cAMP-dependent mechanisms. Optimal steroidogenic capacity is achieved by the actions of ACTH which exerts transcriptional pressure on all steroidogenic genes. The actions of ACTH in the adrenal cortex have been studied in great detail and is mediated by cAMP and protein kinase A (PKA) via two temporally distinct pathways. The acute response leads to mobilization of cholesterol, the initial substrate for all steroidogenic pathways, from cellular stores to the inner mitochondrial membrane where cholesterol sidechain cleavage cytochrome P450 (P45011A1) resides. The slower, chronic response of ACTH in the adrenal cortex directs transcription of the genes encoding the steroidogenic enzymes. Although steroidogenic gene transcription in response to ACTH is cAMP-dependent, the consensus cAMP response pathway (CRE/CREB) is not involved. Instead, each steroidogenic gene utilizes unique cAMP-responsive sequences (CRS) found in the promoters of each gene, which bind a diverse array of transcription factors. Moreover, once specific transcription factors are bound to the promoters of the steroidogenic genes, increased gene expression requires posttranslational modification (phosphorylation/dephosphorylation) of the transcription factors and binding of coactivator proteins. This review provides a general view (with emphasis on the human) of the important factors involved in regulating steroidogenic gene expression and ultimately steroid hormone biosynthesis.

Human skin is a steroidogenic tissue: steroidogenic enzymes and cofactors are expressed in epidermis, normal sebocytes, and an immortalized sebocyte cell line (SEB-1)

Although the human sebaceous gland can synthesize cholesterol from acetate and can further metabolize steroids such as dehydroepiandrosterone into potent androgens, the de novo production of steroids from cholesterol has not been demonstrated in human skin. The goal of this study was to delineate the steroidogenic pathway upstream from dehydroepiandrosterone by documenting the presence of members of the P450 side chain cleavage system (P450scc). This system catalyzes the initial step in steroid hormone synthesis following translocation of cholesterol to the inner mitochondrial membrane. In concert with its cofactors, adrenodoxin and adrenodoxin reductase, and the transcription factor steroidogenic factor 1, P450scc converts cholesterol to pregnenolone. An SV40 immortalized human sebaceous gland cell line (SEB-1) was established in order to facilitate investigation of the P450scc system. The sebaceous phenotype of SEB-1 sebocytes was confirmed using immunohistochemistry, Oil Red O staining, and gene array expression analysis. Presence of P450scc, adrenodoxin reductase, cytochrome P450 17-hydroxylase (P450c17), and steroidogenic factor 1 was documented in human facial skin, human sebocytes, and SEB-1 sebocytes. Using immunohistochemistry, antibodies to the above proteins localized to epidermis, hair follicles, sebaceous ducts, and sebaceous glands in sections of facial skin. Results of immunohistochemistry were confirmed with Western blotting. Biochemical activity of cytochrome P450scc and P450c17 was demonstrated in SEB-1 sebocytes using radioimmunoassay. The relative abundance of mRNA for P450scc, P450c17, and steroidogenic factor 1 in SEB-1 sebocytes and sebaceous glands was compared to mRNA levels in ovarian theca and granulosa cells using real-time quantitative polymerase chain reaction. Gene array expression analysis and quantitative polymerase chain reaction indicated that mRNA for P450scc is more abundant than mRNA for both P450c17 and steroidogenic factor 1 in sebaceous glands and SEB-1 cells. These data demonstrate that the skin is in fact a steroidogenic tissue. The clinical significance of this finding in mediating androgenic skin disorders such as acne, hirsutism, or androgenetic alopecia remains to be established.

Molecular pathogenesis of lipoid adrenal hyperplasia and adrenal hypoplasia congenita

Congenital lipoid adrenal hyperplasia (lipoid CAH) is the most severe form of CAH in which the synthesis of all gonadal and adrenal cortical steroids is markedly impaired. Lipoid CAH may be caused by the defect in either the steroidogenic acute regulatory (StAR) protein or the P450scc. More than 34 different mutations in StAR gene have been identified. Clinically, most of the patients manifest adrenal insufficiency from 1 day to 2 months of age, but some patient show delayed onset of adrenal insufficiency. Affected 46, XY subjects do not show pubertal development, whereas affected 46, XX subjects undergo spontaneous feminization, breast development and cyclical vaginal bleeding at the usual age of puberty. X-linked adrenal hypoplasia congenital (AHC) is a rare congenital adrenal disorder characterized by severe adrenal insufficiency and hypogonadotropic hypogonadism. More than 80 different several intragenic mutations of DAX-1 have been identified. The failure of pubertal development may be caused by either abnormal hypothalamic or pituitary regulation of gonadotropin secretion. In addition, although the testicular steroidogenesis is largely intact, the functional maturity of Sertoli cells and also spermatogenesis are impaired. The type of mutation does not predict clinical phenotype. Thus, unified mechanism how DAX-1 gene defect gives rise to adrenal insufficiency, hypothalamic/pituitary hypogonadism and impaired spermatogenesis remains established.

Parallel early development of zebrafish interrenal glands and pronephros: differential control by wt1 and ff1b

Steroids are synthesized mainly from the adrenal cortex. Adrenal deficiencies are often associated with problems related to its development, which is not fully understood. To better understand adrenocortical development, we studied zebrafish because of the ease of embryo manipulation. The adrenocortical equivalent in zebrafish is called the interrenal, because it is embedded in the kidney. We find that interrenal development parallels that of the embryonic kidney (pronephros). Primordial interrenal cells first appear as bilateral intermediate mesoderm expressing ff1b in a region ventral to the third somite. These cells then migrate toward the axial midline and fuse together. The pronephric primordia are wt1-expressing cells located next to the interrenal. They also migrate to the axial midline and fuse to become glomeruli at later developmental stages. Our gene knockdown experiments indicate that wt1 is required for its initial restricted expression in pronephric primordia, pronephric cell migration and fusion. wt1 also appears to be involved in interrenal development and ff1b expression. Similarly, ff1b is required for interrenal differentiation and activation of the differentiated gene, cyp11a1. Our results show that the zebrafish interrenal and pronephros are situated close together and go through parallel developmental processes but are governed by different signaling events.

Steroidogenic acute regulatory protein in ovarian follicles of gonadotropin-stimulated rats is regulated by a gonadotropin-releasing hormone agonist

The aim of the present study was to examine the acute and chronic effects of the gonadotropin-releasing hormone agonist (GnRH-a) leuprolide acetate (LA) on the expression of the steroidogenic acute regulatory protein (StAR), the cytochrome P450 side-chain cleavage enzyme (P450scc), and steroid production in antral ovarian follicles obtained from prepubertal equine choriogonadotropin (eCG)-treated rats. Follicular contents of StAR and P450scc proteins were measured by Western blotting following in vivo injection of eCG (control) and eCG+LA (LA) to prepubertal rats. Treatment with eCG for 2 h resulted in no change in StAR protein content, but it was markedly increased at 4 and 8 h after hormone treatment. However, coadministration of eCG+LA produced a significant increase (P < 0.05) in StAR protein levels at 2, 4, and 8 h when compared with eCG treatment. Acute and chronic treatment with either eCG or eCG+LA did not alter the P450scc protein levels in freshly isolated follicles. The increase in StAR protein expression following LA treatment was qualitatively similar to StAR mRNA expression, as determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. Furthermore, administration of eCG demonstrated a time-dependent increase (2-8 h) in the levels of StAR mRNA, and these levels were markedly increased by eCG+LA. However, the temporal response pattern of StAR mRNA was much greater at 2 h following LA administration when compared with controls. In addition, 48 h of LA treatment in eCG-treated rats resulted in a significant increase (P < 0.05) in follicular progesterone levels, whereas significant decreases in androgen (testosterone and androsterone) and estradiol levels were observed. Similar results were obtained when serum androgens and estradiol were measured, but serum progesterone levels were unchanged. Collectively, these findings demonstrate that the inhibitory effect of LA on ovarian androgen and estradiol levels is related to changes in the follicular levels of StAR protein and steroid production.

Expression of LDL receptor and uptake of LDL in mouse preimplantation embryos

OBJECTIVES

The aim of this study is to address the role of low-density lipoprotein (LDL) on mouse preimplantation embryos.

METHODS

The temporal expression of low-density lipoprotein receptor (LDLR) and side-chain cleavage cytochrome P450 (P450scc) mRNAs in mouse oocytes and preimplantation embryos up to the hatched blastocyst stage were analyzed by RT-PCR and nested PCR techniques. Simultaneously, the expression of LDLR in the protein level was analyzed by fluorescent immunohistochemistory at oocyte, 4-cell embryo and blastocyst. Uptake of LDL was analyzed using the LDL labeled with the fluorescent probe DiO.

RESULTS

LDLR mRNA was detected at oocyte, 8-cell, morula, blastocyst and hatched blastocyst stages. P450scc mRNA was detected at oocyte, 1-cell, 2-cell, 4-cell, blastocyst and hatched blastocyst stages. LDLR protein was detected in blastocyst. P450scc protein was detected in oocyte, 4-cell, and blastocyst. LDL-DiO was taken into embryo at blastocyst stage and this uptake was competitively suppressed by excess unlabeled LDL.

CONCLUSIONS

It is suggested from the present study that LDLR may play an essential role in uptake of exogenous LDL into blastocyst stage and cholesterol derived from LDL may be the source of steroid hormone synthesis.

Formation and functioning of fused cholesterol side-chain cleavage enzymes

We studied the properties of various fused combinations of the components of the mitochondrial cholesterol side-chain cleavage system including cytochrome P450scc, adrenodoxin (Adx), and adrenodoxin reductase (AdR). When recombinant DNAs encoding these constructs were expressed in Escherichia coli, both cholesterol side-chain cleavage activity and sensitivity to intracellular proteolysis of the three-component fusions depended on the species of origin and the arrangement of the constituents. To understand the assembly of the catalytic domains in the fused molecules, we analyzed the catalytic properties of three two-component fusions: P450scc-Adx, Adx-P450scc, and AdR-Adx. We examined the ability of each fusion to carry out the side-chain cleavage reaction in the presence of the corresponding missing component of the whole system and examined the dependence of this reaction on the presence of exogenously added individual components of the double fusions. This analysis indicated that the active centers in the double fusions are either unable to interact or are misfolded; in some cases they were inaccessible to exogenous partners. Our data suggest that when fusion proteins containing P450scc, Adx, and AdR undergo protein folding, the corresponding catalytic domains are not formed independently of each other. Thus, the correct folding and catalytic activity of each domain is determined interactively and not independently.

Critical role of the plasma membrane for expression of mammalian mitochondrial side chain cleavage activity in yeast

Engineered yeast cells efficiently convert ergosta-5-eneol to pregnenolone and progesterone provided that endogenous pregnenolone acetylase activity is disrupted and that heterologous sterol delta7-reductase, cytochrome P450 side chain cleavage (CYP11A1) and 3beta hydroxysteroid dehydrogenase/isomerase (3beta-HSD) activities are present. CYP11A1 activity requires the expression of the mammalian NADPH-adrenodoxin reductase (Adrp) and adrenodoxin (Adxp) proteins as electron carriers. Several parameters modulate this artificial metabolic pathway: the effects of steroid products; the availability and delivery of the ergosta-5-eneol substrate to cytochrome P450; electron flux and protein localization. CYP11A1, Adxp and Adrp are usually located in contact with inner mitochondrial membranes and are directed to the outside of the mitochondria by the removal of their respective mitochondrial targeting sequences. CYP11A1 then localizes to the plasma membrane but Adrp and Adxp are detected in the endoplasmic reticulum and cytosol as expected. The electron transfer chain that involves several subcellular compartments may control side chain cleavage activity in yeast. Interestingly, Tgl1p, a potential ester hydrolase, was found to enhance steroid productivity, probably through both the availability and/or the trafficking of the CYP11A1 substrate. Thus, the observation that the highest cellular levels of free ergosta-5-eneol are found in the plasma membrane suggests that the substrate is freely available for pregnenolone synthesis.

Changes in the expression of steroid metabolism-related genes in rat adrenal glands during selective REM sleep deprivation

Selective REM sleep deprivation was carried out under the conditions designed to minimize the adverse influence of environmental conditions and restricted movement, and the influence of REM sleep deprivation on adrenocortical steroid metabolism was investigated by measuring the steady-state levels of mRNAs encoding steroid metabolism-related genes, steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme cytochrome P450 (P450scc) and steroid 5alpha-reductase (5alpha-R), in rat adrenal glands. Selective REM sleep deprivation caused a significant decrease in StAR mRNA and an increase in 5alpha-R mRNA levels without any notable change in P450scc mRNA levels in the adrenal gland. In contrast, non-selective sleep disturbance, resulting in the partial reductions of non-REM and REM sleep, tended to increase both StAR and P450scc mRNA levels without any statistical significance. These results indicate that REM sleep deprivation by itself may affect the expression of steroid metabolism-related genes in the adrenal gland, suggesting a possible relation between REM sleep and adrenocortical steroid metabolism.

Exposure of neonatal rats to diethylstilbestrol affects the expression of genes involved in ovarian differentiation

Exposing neonatal rats with the synthetic estrogen, diethylstilbestrol (DES), induces morphological and functional abnormalities in the adult ovary. We examined the events that lead to this condition using female rats that were exposed to DES for the first five days after birth. The expression of steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage cytochrome P450 (P450scc), which are both required for steroidogenesis in the theca/interstitial region was markedly reduced. The expression of Mullerian inhibiting substance (MIS) was transiently increased in small growing follicles in the ovary of DES-treated rats at postnatal day 7 (P7), and the expression profile in the ovary differed between DES- and vehicle oil-treated rats at P14 and P21. The expression of the transcription factor, steroidogenic factor-1 (SF-1), reduced in theca/interstitial cells, but increased in granulosa cells of primary follicles. These results indicate that altered steroidogenesis and MIS production are mechanisms through which DES induces abnormal ovarian development, and support the notion that androgens and MIS are both critical factors in regulating early ovarian differentiation.

Hippocampal cytochrome P450s synthesize brain neurosteroids which are paracrine neuromodulators of synaptic signal transduction

Hippocampal pyramidal neurons and granule neurons of adult male rats are equipped with a complete machinery for the synthesis of pregnenolone, dehydroepiandrosterone, 17beta-estradiol and testosterone as well as their sulfate esters. These brain neurosteroids are synthesized by cytochrome P450s (P450scc, P45017alpha and P450arom) from endogenous cholesterol. Synthesis is acutely dependent on the Ca(2+) influx attendant upon neuron-neuron communication via N-methyl-D-aspartate (NMDA) receptors. Pregnenolone sulfate, estradiol and corticosterone rapidly modulate neuronal signal transduction and the induction of long-term potentiation via NMDA receptors and putative membrane steroid receptors. Brain neurosteroids are therefore promising neuromodulators that may either activate or inactivate neuron-neuron communication, thereby mediating learning and memory in the hippocampus.

Effects of deletion of the prolactin receptor on ovarian gene expression

Prolactin (PRL) exerts pleiotropic physiological effects in various cells and tissues, and is mainly considered as a regulator of reproduction and cell growth. Null mutation of the PRL receptor (R) gene leads to female sterility due to a complete failure of embryo implantation. Pre-implantatory egg development, implantation and decidualization in the mouse appear to be dependent on ovarian rather than uterine PRLR expression, since progesterone replacement permits the rescue of normal implantation and early pregnancy. To better understand PRL receptor deficiency, we analyzed in detail ovarian and corpora lutea development of PRLR-/- females. The present study demonstrates that the ovulation rate is not different between PRLR+/+ and PRLR-/- mice. The corpus luteum is formed but an elevated level of apoptosis and extensive inhibition of angiogenesis occur during the luteal transition in the absence of prolactin signaling. These modifications lead to the decrease of LH receptor expression and consequently to a loss of the enzymatic cascades necessary to produce adequate levels of progesterone which are required for the maintenance of pregnancy.

Anti-tumor mechanism of Z-100, an immunomodulatory Arabinomannan extracted from Mycobacterium tuberculosis strain Aoyama B, on pulmonary metastases of B16F10 melanoma: restoration of helper T cell responses via suppression of glucocorticoid-genesis

In the present study, the anti-tumor mechanism of Z-100 was investigated with the use of pulmonary metastasis of B16F10 melanoma. In B16F10 mice, Th1 cytokine production (IL-2, IFN-gamma) was suppressed in comparison with normal mice. On the other hand, Th2 cytokine production (IL-4, IL-10) was increased in the B16F10 mice. The administration of Z-100 to B16F10 mice restored the balance of Th1/Th2 cell responses from the Th2 dominant state to the normal state. Z-100 significantly suppressed the pulmonary metastasis of B16F10 melanoma in a dose-dependent manner. These results suggest that Z-100 restored the breakdown of Th1 cell responses, resulting in the suppression of pulmonary metastasis of B16F10 melanoma. Moreover, Z-100 decreased the corticosterone levels, which is known to suppress the Th1 cell responses, in both serum specimens and splenic tissue, and the steroidogenic CYP11A1 mRNA expression in CD4+ T cells. These results suggest that a suppression of pulmonary metastasis and restoration of Thl/Th2 cell responses by Z-100 may be due to the decrease in the corticosterone levels and the steroidogenic CYP11A1 mRNA expression of CD4+ T cells in B16F10 mice. Further, the role of Th1 cytokine, IFN-gamma, on these activities of Z-100 was examined. The suppressive effects of Z-100 on pulmonary metastasis and restoration of Th1/Th2 cell responses were eliminated by the administration of anti-IFN-gamma mAb. Moreover, the suppressive effects of Z-100 on glucocorticoid-genesis were eliminated by the administration of anti-IFN-gamma-mAb. These results suggest that Z-100 restores the balance of Th1/Th2 cell responses via the suppression of glucocorticoid-genesis by Z-100-induced IFN-gamma. IFN-gamma acts as a key cytokine in anti-tumor activities of Z-100.

Effects of Vinclozolin Administration on Sperm Production and Testosterone Biosynthetic Pathway in Adult Male Rat

The effect of vinclozolin (VCZ), used as a fungicide and known to have anti-androgenic effects on spermatogenesis and gene expression in the male rat testis was investigated. In Experiment 1, VCZ (100 mg/kg/day) or flutamide (FM, 25 mg/kg/day) was orally administered to male Holzman rats for six days. 8 days after the last administration (D8), a drastic increase in intratesticular testosterone was detected in FM (4.2-fold over control) but not in VCZ treated animals, whereas on D36 post-administration, both groups showed similar levels. Significant decreases in daily sperm production were seen in both VCZ and FM-treated rats on D36. Semiquantitative RT-PCR analysis with testicular and pituitary mRNAs on D8 revealed that LHbeta and FSHbeta mRNAs were increased in the pituitary by VCZ, as well as by FM. Among the four testicular steroidogenic enzyme genes, cytochrome P450 side chain cleavage (P450scc) and cytochrome P450 17alpha/C(17-20) lyase (P450c17) mRNAs were significantly increased, whereas 17beta-hydroxysteroid dehydrogenase type III (17betaHSD) mRNA was not changed. A significant increase in 3beta-hydroxysteroid dehydrogenase type I (3betaHSD) and a decrease in androgen receptor (AR) mRNA were observed only in FM treated rats. Immunohistochemistry demonstrated intense staining of P450scc in the interstitial cells of VCZ-treated testis on D8. In Experiment 2, hormone levels were measured at 1, 3, 6, 12 and 24 hours after VCZ (100 mg/kg) administration to Sprague-Dawley rats. Serum LH level remained constant for the first 3 hours and started to increase at 6 hrs. In contrast, serum and intratesticular testosterone levels increased 2-fold at 1 hr and maintained the level until 24 hrs. P450c17 mRNA level was 2-fold increased at all periods, whereas no obvious changes were detected in the other steroidogenic enzyme genes. Although not statistically significant, AR mRNA level increased 2-fold, 3 hrs after VCZ administration. These results indicate that VCZ affects the pituitary in a similar manner as FM, but functions differently on testicular gene expression.

Effects of various N-terminal addressing signals on sorting and folding of mammalian CYP11A1 in yeast mitochondria

Topogenesis of cytochrome p450scc, a resident protein of the inner membrane of adrenocortical mitochondria, is still obscure. In particular, little is known about the cause of its tissue specificity. In an attempt to clarify this point, we examined the process in Saccharomyces cerevisiae cells synthesizing cytochrome p450scc as its native precursor (pCYP11A1) or versions in which its N-terminal addressing presequence had been replaced with those of yeast mitochondrial proteins: CoxIV(1-25) and Su9(1-112). We found the pCYP11A1 and CoxIV(1-25)-mCYP11A1 versions to be effectively imported into yeast mitochondria and subjected to proteolytic processing. However, only minor portions of the imported proteins were incorporated into mitochondrial membranes, whereas their bulk accumulated as aggregates insoluble in 1% Triton X-100. Along with previously published data, this suggests that a distinguishing feature of the import of the CYP11A1 precursors into yeast mitochondria is their easy translocation into the matrix where the foreign proteins mainly undergo proteolysis or aggregation. The fraction of CYP11A1 that happens to be inserted into the inner mitochondrial membrane is effectively converted into the catalytically active holoenzyme. Experiments with the Su9(1-112)-mCYP11A1 construct bearing a re-export signal revealed that, after translocation of the fused protein into the matrix and its processing, the Su9(67-112) segment ensures association of the mCYP11A1 body with the inner membrane, but proper folding of the latter does not take place. Thus it can be said that the most specific stage of CYP11A1 topogenesis in adrenocortical mitochondria is its confinement and folding in the inner mitochondrial membrane. In yeast mitochondria, only an insignificant portion of the imported CYP11A1 follows this mechanism.

Expression of messenger ribonucleic acid encoding steroidogenic enzymes in postmenopausal ovaries

To investigate expression of steroidogenic enzymes involved in androgen and estrogen synthesis in the stroma of postmenopausal ovaries.Ovarian stromal tissue samples were obtained at hysterectomy from postmenopausal women who had hysterectomy and oophorectomy. Tissues were frozen immediately in liquid nitrogen and kept frozen until RNA was extracted. Total RNA was examined by Northern blot analysis using (32)P-labeled cDNA probes encoding human P450 side chain cleavage (P450(SSC)), P450(17alpha), and cytochrome P450 aromatase (P450(arom)). Concentrations of mRNA encoding cytochrome P450(SSC), cytochrome P450 17alpha-hydroxylase (CYP17), and P450(arom) were determined in the ovarian stroma. We detected P450(SSC) mRNA in all postmenopausal ovaries studied. P450(SSC) mRNA was increased threefold in the ovarian stroma of postmenopausal women with endometrial cancer and endometrial hyperplasia. CYP17 mRNA was detected in the ovarian stroma of all women with endometrial cancer. P450(arom) mRNA was not detected in the ovaries studied. Postmenopausal ovaries possess enzymes for initiation of steroidogenesis. Enzymes essential for androgen synthesis were expressed in the ovarian stroma of postmenopausal women with endometrial cancer or hyperplasia.

Adrenocorticotrophic hormone (ACTH) stimulation of sheep fetal adrenal cortex can occur without increased expression of ACTH receptor (ACTH-R) mRNA

In the present study, it was hypothesized that the adrenocorticotrophin hormone receptor (ACTH-R) would be up-regulated in the adrenal gland of the sheep fetus following infusion of physiological amounts of ACTH, as shown for adrenal cortical cells in culture. In chronically catheterized sheep, an intravenous infusion of ACTH(1-24) was given to 6 fetuses for 24 h at a rate of 0.5 microg h(-1), starting on Day 126 or 127 of gestation (term approximately 147 days). Four control fetuses received an infusion of vehicle (saline). Total RNA was extracted from the fetal adrenal glands by the guanidinium thiocyanate method. Expression of specific mRNAs was determined by ribonuclease protection assay using cRNA probes directed against: ACTH-R; the steroid enzymes side-chain cleavage (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17apha-hydroxylase (P450c17) and 21beta-hydroxylase (P450c21); and beta-actin. Ratios of mRNA expression to beta-actin mRNA expression (arbitrary units) were calculated to correct for differences in RNA quality between samples. The concentration (mean +/- SEM) of immunoreactive cortisol in fetal plasma was greater after ACTH infusion than after vehicle infusion (47 +/- 3 v. 13 +/- 2 ng mL(-1) respectively; P<0.001). Adrenal expression of P450scc and P450c21 mRNA increased after ACTH infusion (P<0.05), whereas expression of P450c17 and 3beta-HSD mRNA was unchanged. There was no difference in ACTH-R mRNA expression between ACTH- and vehicle-infused fetuses (254 +/- 48 v. 305 +/- 76 arbitrary units respectively). It was concluded that ACTH is able to increase plasma cortisol concentrations in the sheep fetus by up-regulating cortisol synthesis in the adrenal gland, but that in vivo this does not require up-regulation of ACTH-R mRNA.

Expression of zebrafish cyp11a1 as a maternal transcript and in yolk syncytial layer

Cyp11a1 (P450scc, cholesterol side-chain cleavage enzyme) is the first enzyme for the synthesis of all steroid hormones. The regulation of steroid synthesis has been extensively investigated, except during embryogenesis. To study steroidogenesis in embryos, we have isolated the zebrafish cyp11a1 gene, which consists of 11 exons. Reverse transcription-polymerase chain reaction analysis indicates that zebrafish cyp11a1 is expressed temporally in two waves during embryonic stages and when sexual differentiation begins. It is expressed in adult brain, testicular Leydig cells, and the granulosa/theca layer of the ovary. In addition, zebrafish cyp11a1 is expressed in oocytes, and is inherited as a maternal transcript in early embryos. Throughout zebrafish epiboly and segmentation stages, cyp11a1 is expressed in the yolk syncytial layer. At 36 h post fertilization, cyp11a1 transcript is located ventral to the third somite, where the primordial interrenal gland is located. In summary, zebrafish cyp11a1 is expressed in the cytoplasm of oocytes, as a maternal transcript, and in yolk syncytial layer during early embryogenesis.

The genetic basis of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age. The disorder is characterized by clinical features of hyperandrogenism, menstrual irregularities and often central obesity and hyperinsulinaemia. PCOS may increase the risk for infertility, type 2 diabetes mellitus, dyslipidaemia, cardiovascular disease and endometrial cancer, emphasizing the need for early diagnosis of the syndrome. The genetic basis of PCOS is unknown. There is a strong familial component but the mode of inheritance is uncertain and several candidate genes have been proposed to contribute to susceptibility. Not only genes involved in steroid hormone biosynthesis have been studied but also genes associated with the regulation of insulin secretion and action since hyperinsulinaemia is a characteristic of PCOS. So far there is evidence that INS VNTR (insulin variable number of tandem repeats) or CYP11alpha (cholesterol side chain cleavage) genes are associated with this syndrome. PCOS appears, however, to be an oligogenic disorder and more studies are necessary to define the genetic basis.

11beta-hydroxylase and aldosterone synthase expression in fetal rat hippocampal neurons

The central nervous system produces many of the enzymes responsible for corticosteroid synthesis. A model system to study the regulation of this local system would be valuable. Previously, we have shown that primary cultures of hippocampal neurons isolated from the fetal rat can perform the biochemical reactions associated with the enzymes 11beta-hydroxylase and aldosterone synthase. Here, we demonstrate directly that these enzymes are present within primary cultures of fetal rat hippocampal neurons.

Function of the transcriptional regulating protein of 132 kDa (TReP-132) on human P450scc gene expression

Cytochrome P450scc catalyzes the important first step in the steroid synthesis pathway; however, it is clear that additional factors regulating the temporal and spacial specific expression of the CYP11A1 gene remain to be identified. To isolate novel transcription factors that regulate this gene, a cis-acting element of the 5'-flanking region from nucleotides -155 to -131 (-155/-131) was used to screen a human placental lambda gt11 cDNA expression library, and an interacting clone was isolated. The open reading frame of the cDNA encodes several domains that are characteristic of transcription factors including an acidic region, a region rich in prolines and three zinc-finger motifs. Expression of the cDNA by in vitro transcription/translation and by transient transfection in HeLa cells yielded a protein of 132 kDa, which concurs with the predicted size. Transfection of the cDNA in placental JEG-3 and adrenal NCI-H295 cells, stimulate expression of a reporter construct controlled by the P450scc gene 5'-flanking region from nucleotides -1676 to +49. This transcriptional regulating protein of 132kDa (TReP-132) when expressed in HeLa cells was demonstrated to interact with the -155/-131 region in bandshift analysis, and tandem copies of this region was shown to confer activation of the heterologous HSV thymidine kinase minimal promoter. Coexpression of CBP/p300 with TReP-132 further increased promoter activity, and the proteins were demonstrated to interact physically. RNA analysis demonstrated the highest levels of expression in the adrenal cortex and testis; and transcript expression is also found in the steroidogenic JEG-3, NCI-H295, and MCF-7 cell lines, but not in non-steroidogenic HepG2 and HK293 cells. Subsequently it has been shown that TReP-132 interacts with steroidogenic factor-1 (SF-1) through specific domains; and along with the interaction with CBP/p300 these factors are postulated to form a complex to regulate expression of the P450scc gene.