Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cDNA encoding the catfish ovarian aromatase has previously been isolated and described (accession number S75715). As demonstrated previously, the predicted amino acid sequence and enzymatic activity of the encoded protein share a significant degree of similarity to the forms of aromatase found in other vertebrates. Analyses utilizing reverse transcription coupled with the polymerase chain reaction (RT-PCR) demonstrate the expression of aromatase mRNA in catfish brain, testis and ovary. In spite of the evidence provided by Northern blot analysis for a single transcript encoding ovarian aromatase, RT-PCR analysis indicated transcript heterogeneity within the ovary, but not the testis or the brain. Although not characterized, PCR analysis indicated that the transcript complexity of ovarian aromatase was within the encoding region. Until this study, the expression of aromatase and its correlation with the reproductive physiology of fish had not been studied at the molecular level. In the catfish, significant changes in ovarian development were evident following elevation of plasma estradiol titers during October and again in February. Seasonal changes in the expression of ovarian aromatase and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) mRNA was reflected in estradiol plasma titers. Ovarian expression of 3beta-HSD mRNA commenced a month before the message for aromatase was detected. Both transcripts were present from October to April. As the female approached the time of spawning (in May), the abundance of both aromatase and 3beta-HSD transcripts decreased. The aromatase message was not detected in post-spawning females but 3beta-HSD transcripts were evident. These data indicate that the timely synthesis of estradiol in catfish is caused by the regulation of both 3beta-HSD and aromatase.
J Steroid Biochem Mol Biol 1997 Apr
PMID:Expression of cytochrome P450 aromatase in the channel catfish, Ictalurus punctatus. 936 16

The present study was undertaken to investigate intraovarian mechanism(s) for the antiovulatory effect of Onapristone (ON), because antiprogestins possessing the same antiprogestational activity and inhibiting the preovulatory LH surge to the same extent differ in their antiovulatory potency. Ovulation was induced by treating immature female rats with pregnant mare serum gonadotropin (PMSG) for folliculogenesis and hCG for the induction of ovulation. The animals were treated twice with ON (200 mg/kg 42 h and 48 h after PMSG) and killed at different times. The ovulation rate was assessed by counting the number of ova in the fallopian tubes and uteri. Blood and ovaries were collected for radioimmunoassay (RIA) of steroid hormones and histological analysis for 3beta-hydroxysteroid dehydrogenase (3beta-HSDH), 17beta-hydroxysteroid dehydrogenase (17beta-HSDH), progesterone (PR), estrogen (ER) and androgen (AR) receptors. Treatment with ON totally blocked ovulation and the progesterone (P4) surge was significantly diminished in comparison to the control (6-8 h post-hCG), whereas androgen levels remained unaffected. The decreased P4 concentrations correlated well with a reduced staining intensity of 3beta-HSDH in granulosa cells of tertiary follicles. Moreover, we observed a down-regulation of PR in granulosa cells of tertiary follicles. Additionally, in secondary and tertiary follicles the expression of AR between 0 and 6 h after hCG was reduced. These results suggest that the antiovulatory effect of the antiprogestin ON is related to down-regulation of intraovarian progesterone, caused by attenuated 3beta-HSDH activity and PR expression. One can thus assume that intraovarian P4 is an important factor for the induction of ovulation. An effect of ON on the staining intensity of 17beta-HSDH in theca and granulosa cells could not be observed at any time. In conclusion, the inhibition of ovulation induced by the antiprogestin, ON, could be related to decreased intraovarian progesterone production through reduced 3beta-HSDH activity and the down-regulation of PR.
J Steroid Biochem Mol Biol 1997 May
PMID:The antiovulatory effect of the antiprogestin onapristone could be related to down-regulation of intraovarian progesterone (receptors). 936 4

This study investigated the mechanisms underlying 2-hydroxyestradiol (2-OHE2) effect on luteal steroidogenesis using serum-free cultures of mixed luteal cells from day 8 pseudopregnant rats. Initially, interactions between 2-OHE2 and LH or dibutyryl (db)cAMP on progesterone production were investigated. LH (250 ng/ml) and 2-OHE2 (2.5 microg/ml) had comparable effects on progesterone accumulation, while dbcAMP (5 mM) was more stimulatory. When applied together, 2-OHE2 did not synergize with LH or dbcAMP to further enhance progesterone accumulation. Furthermore, in time course experiments, the dose-dependent effect of 2-OHE2 was to reduce and eventually abolish the time-dependent increase in cAMP accumulation. In contrast LH stimulated cAMP accumulation at all times. Experiments in which cells were co-treated with 2-OHE2, 22-OH-cholesterol and cyanoketone, or with 2-OHE2 and 22-OH-cholesterol or pregnenolone indicated that 2-OHE2 not only had a stimulatory effect on the cholesterol side-chain cleavage and 3beta-hydroxysteroid dehydrogenase enzymes, but it also appeared to inhibit the 20alpha-hydroxysteroid dehydrogenase leading to a relative increase in progesterone accumulation. Experiments with hormone antagonists suggested that the actions of 2-OHE2 were not mediated by the estrogen, alpha- or beta-adrenergic receptors. The results of this study support the concept of a physiological role for catecholestrogens in rat luteal steroidogenesis.
Mol Cell Endocrinol 1994 May
PMID:Catecholestrogen modulation of steroid production by rat luteal cells: mechanism of action. 939 36

The rat H540 Leydig cell tumor has been shown to express cholesterol side-chain cleavage and 17alpha-hydroxylase cytochrome P450s, 3beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase, and steroid 5alpha-reductase, making it a useful model in which to study steroidogenesis. In the current studies, we report that cultured H540 cells express high levels of aromatase cytochrome P450 (P450arom), which converts androgens to estrogens. Levels of aromatase activity varied from 9.4 to 51.7 pmol/h/mg protein and inhibition of 5alpha-reductase with finasteride did not significantly effect aromatase measurements, indicating that 5alpha-reductase is not competing for the substrate used in the aromatase assays. Aromatase activity was decreased 95% by preincubating the cells with 4-hydroxyandrostenedione, an aromatase inhibitor. Characterization of the aromatase mRNA expressed in the H540 cell line demonstrates that, like R2C cells and rat ovarian tissue, three distinct P450arom mRNA species are detected by Northern analysis, and that these transcripts are derived from the same site of transcription initiation. Despite these similarities, the regulation of aromatase activity by 8-bromo-cAMP in H540 cells differs from both R2C cells and rat ovarian tissue. As the H540 and R2C cell lines appear to have distinct origins, H540 is the second rat Leydig tumor cell line characterized that constitutively expresses high levels of aromatase.
J Steroid Biochem Mol Biol
PMID:Expression of aromatase cytochrome P450 in rat H540 Leydig tumor cells. 944 4

Steroid metabolism was investigated in cultured human B-lymphoblastoid cells (B-LCL), and peripheral blood T and B cells. Gene expression was examined by reverse-transcription polymerase chain reaction amplification (RT-PCR). Appropriate sized transcripts were detected in both cultured and fresh peripheral lymphocytes for CYP11A, CYP17, HSD11L (11beta-hydroxysteroid dehydrogenase I), HSD17B1 (17beta-hydroxysteroid dehydrogenase type I) and SRD5A1 (5alpha-reductase I). B-LCL, but not T and B cells, expressed CYP11B. There was minimal expression of HSD3B1 and HSD3B2 (3beta-hydroxysteroid dehydrogenase I and II) in B-LCL and T cells. Transcripts for CYP19 and HSD11K were not detected. Corresponding enzymatic activity was detectable only for 17-hydroxysteroid dehydrogenase and 5alpha-reductase, respectively producing testosterone and 5alpha-dihydrotestosterone. Steroid identities were confirmed by gas chromatography/mass spectrometry (GC/MS). One metabolite thought to be deoxycorticosterone was identified by GC/MS as 6alpha-hydroxypregnanolone. It was concluded that sex hormone metabolism, including androgen synthesis, occurs in lymphocytes, and may modulate immune response.
Mol Cell Endocrinol 1998 Mar 16
PMID:Prominent sex steroid metabolism in human lymphocytes. 968 15

Sex steroids play a predominant role in the development and differentiation of normal mammary gland as well as in the regulation of hormone-sensitive breast cancer growth. There is evidence suggesting that local intracrine formation of sex steroids from inactive precursors secreted by the adrenals namely, dehydroepiandrosterone (DHEA) and 4-androstenedione (4-dione) play an important role in the regulation of growth and function of peripheral target tissues, including the breast. Moreover, human breast carcinomas are often infiltrated by stromal/immune cells secreting a wide spectra of cytokines. These might in turn regulate the activity of both immune and neoplastic cells. The present study was designed to examine the action of cytokines on 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) activities in human breast cancer cells. The various types of human 17beta-HSD (five types) and 3beta-HSD (two types), because of their tissue- and cell-specific expression and substrate specificity, provide each cell with necessary mechanisms to control the level of intracellular active androgens and estrogens. We first investigated the effect of exposure to IL-4 and IL-6 on reductive and oxidative 17beta-HSD activities in both intact ZR-75-1 and T-47D human breast cancer cells. In ZR-75-1 cells, a 6 d exposure to IL-4 and IL-6 decreased E2-induced cell proliferation, the half maximal inhibitory effect being exerted at 88 and 26 pM, respectively. In parallel, incubation with IL-4 and IL-6 increased oxidative 17beta-HSD activity by 4.4- and 1.9-fold, respectively, this potent activity being observed at EC50 values of 22.8 and 11.3 pM, respectively. Simultaneously, reductive 17beta-HSD activity leading to E2 formation was decreased by 70 and 40% by IL-4 and IL-6, respectively. Moreover, IL-4 and IL-6 exerted the same regulatory effects on 17beta-HSD activities when testosterone and 4-dione were used as substrates, thus strongly suggesting the expression of the type 2 17beta-HSD ZR-75-1 cells. In contrast, in T-47D cells, IL-4 increased the formation of E2, whereas IL-6 exerts no effect on this parameter. However, we found that T-47D cells failed to convert testosterone efficiently into 4-DIONE, thus suggesting that there is little or no expression of type 2 17beta-HSD in this cell line. The present findings demonstrate that the potent regulatory effects of IL-4 and IL-6 on 17beta-HSD activities depend on the cell-specific gene expression of various types of 17beta-HSD enzymes. We have also studied the effect of cytokines on the regulation of the 3beta-HSD expression in both ZR-75-1 and T-47D human breast cancer cells. Under basal culture conditions, there is no 3beta-HSD activity detectable in these cells. However, exposure to IL-4 caused a rapid and potent induction of 3beta-HSD activity, whereas IL-6 failed to induce 3beta-HSD expression. Our data thus demonstrate that cytokines may play a crucial role in sex steroid biosynthesis from inactive adrenal precursors in human breast cancer cells.
J Steroid Biochem Mol Biol 1998 Apr
PMID:Regulation of sex steroid formation by interleukin-4 and interleukin-6 in breast cancer cells. 969 68

To ascertain the potential role of heterozygosity for 3beta-hydroxysteroid (3beta-HSD) deficiency in children with premature pubic hair and adolescent girls with hyperandrogenism, we performed single-strand conformational polymorphism (SSCP) analysis of the 3beta-hydroxysteroid dehydrogenase type 2 (3beta-HSD2) gene in 34 hyperandrogenic patients. Three sequence variants, two missense mutations and a 3'-UTR sequence variant, were detected among seven patients and in none of 100 healthy control subjects. One of these seven patients carried Leu236 --> Ser on one 3beta-HSD2 allele and Glu318 --> STOP on one 21-hydroxylase (CYP21) allele. ACTH stimulation tests were performed in 5/7 patients with sequence variants and were compatible with decreased 3beta-hydroxysteroid dehydrogenase activity in three. Thus, 7 of 34 (20.6%) mildly hyperandrogenic patients carry heterozygous sequence variants of the 3beta-HSD2 gene. Since obligate heterozygotic carriers for congenital adrenal hyperplasia are typically asymptomatic, other genetic or environmental influences may contribute to the expression of hyperandrogenic symptoms in our patients.
Mol Genet Metab 1998 Jul
PMID:Variants of the type II 3beta-hydroxysteroid dehydrogenase gene in children with premature pubic hair and hyperandrogenic adolescents. 971 27

3beta-hydroxysteroid dehydrogenase/steroid delta5-->4-isomerase (3beta-HSD/isomerase) was expressed by baculovirus in Spodoptera fungiperda (Sf9) insect cells from cDNA sequences encoding human wild-type I (placental) and the human type I mutants - H261R, Y253F and Y253,254F. Western blots of SDS-polyacrylamide gels showed that the baculovirus-infected Sf9 cells expressed the immunoreactive wild-type, H261R, Y253F or Y253,254F protein that co-migrated with purified placental 3beta-HSD/isomerase (monomeric Mr=42,000 Da). The wild-type, H261R and Y253F enzymes were each purified as a single, homogeneous protein from a suspension of the Sf9 cells (5.01). In kinetic studies with purified enzyme, the H261R mutant enzyme had no 3beta-HSD activity, whereas the Km and Vmax values of the isomerase substrate were similar to the values obtained with the wild-type and native enzymes. The Vmax (88 nmol/min/mg) for the conversion of 5-androstene-3,17-dione to androstenedione by the Y253F isomerase activity was 7.0-fold less than the mean Vmax (620 nmol/min/mg) measured for the isomerase activity of the wild-type and native placental enzymes. In microsomal preparations, isomerase activity was completely abolished in the Y253,254F mutant enzyme, but Y253,254F had 45% of the 3beta-HSD activity of the wild-type enzyme. In contrast, the purified Y253F, wild-type and native enzymes had similar Vmax values for substrate oxidation by the 3beta-HSD activity. The 3beta-HSD activities of the Y253F, Y253,254F and wild-type enzymes reduced NAD+ with similar kinetic values. Although NADH activated the isomerase activities of the H261R and wild-type enzymes with similar kinetics, the activation of the isomerase activity of H261R by NAD+ was dramatically decreased. Based on these kinetic measurements, His261 appears to be a critical amino acid residue for the 3beta-HSD activity, and Tyr253 or Tyr254 participates in the isomerase activity of human type I (placental) enzyme.
J Steroid Biochem Mol Biol 1998 Sep
PMID:Site-directed mutagenesis identifies amino acid residues associated with the dehydrogenase and isomerase activities of human type I (placental) 3beta-hydroxysteroid dehydrogenase/isomerase. 974 38

Sex steroids play a crucial role in the development and differentiation of normal mammary gland as well as in the regulation of breast cancer growth. Local intracrine formation of sex steroids from inactive precursors secreted by the adrenals, namely, dehydroepiandrosterone and its sulfate, may regulate growth and function of peripheral target tissues, including the breast. Both endocrine and paracrine influences on the proliferation of human breast cancer cells are well recognized. Breast tumors harbor tumor-associated macrophages and tumor-infiltrating lymphocytes that secrete a wide spectrum of cytokines. These factors may also contribute to neoplastic cell activity. The present study was designed to investigate the action of cytokines on 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity, which is an essential step in the biosynthesis of active estrogens and androgens in human breast cancer cell lines and in normal human mammary epithelial cells in primary culture. 3Beta-HSD activity was undetectable in ZR-75-1 and T-47D estrogen receptor-positive (ER)+ cells under basal growth conditions. This activity was markedly induced after exposure to picomolar concentrations of interleukin (IL)-4 or IL-13. The potent stimulatory effect of these cytokines on 3beta-HSD activity was also observed in the ER- MDA-MB-231 human breast cancer cell line and in normal human mammary epithelial cells (HMECs) in primary culture. The stimulation of 3beta-HSD activity by IL-4 and IL-13 results from a rapid increase in 3beta-HSD type 1 mRNA levels as measured by RT-PCR and Northern blot analyses. Such an induction of the 3beta-HSD activity may modulate androgenic and estrogenic biological responses as demonstrated using ZR-75-1 cells transfected with androgen- or estrogen-sensitive reporter constructs and treated with the adrenal steroid 5-androstene-3beta,17beta-diol. The DNA-binding activity of Stat6, a member of the signal transducers and activators of transcription gene family, is activated 30 min after exposure to IL-4 and IL-13 in human breast cancer cell lines as well as in HMECs in primary culture. In these cells, Stat6 activated by IL-4 or IL-13 binds to two regions of the 3beta-HSD type 1 gene promoter, containing Stat6 consensus sequences. IL-4 induction of 3beta-HSD mRNA and activity is sensitive to staurosporine. This protein kinase inhibitor also inhibits IL-4-induced Stat6 DNA-binding activity. Our data demonstrate for the first time that IL-4 and IL-13 induce 3beta-HSD type 1 gene expression, thus suggesting their involvement in the fine control of sex steroid biosynthesis from adrenal steroid precursors in normal and tumoral human mammary cells. Furthermore, aromatase and/or 5alpha-reductase(s) are expressed in the mammary gland and in a large proportion of human breast tumors. An increase in the formation of their substrates, namely, 4-androstenedione and testosterone, may well have a significant impact on the synthesis of active estrogens and androgens in these tissues.
Mol Endocrinol 1999 Jan
PMID:Induction of 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase type 1 gene transcription in human breast cancer cell lines and in normal mammary epithelial cells by interleukin-4 and interleukin-13. 989 13

We have demonstrated that continuous administration of a gonadotropin-releasing hormone agonist (GnRH-Ag) suppresses luteal steroidogenesis in the pregnant rat. We further demonstrated that the peripheral-type benzodiazepine receptor (PBR) and the steroidogenic acute regulatory protein (StAR) play key roles in cholesterol transport leading to steroidogenesis. The purpose of this study was to understand the cellular and molecular mechanisms involved in the suppression of luteal steroidogenesis leading to a fall in serum progesterone levels in GnRH-Ag-treated rats during early pregnancy. Pregnant rats were treated individually starting on day 8 of pregnancy with 5 microgram/day GnRH-Ag using an osmotic minipump. Sham-operated control rats received no treatment. At 0, 4, 8 and 24 h after initiation of the treatment, rats were killed and corpora lutea (CL) were removed for PBR mRNA, protein and radioligand binding analyses, immunoblot 1-D gel analysis of StAR, P450 scc and 3beta-hydroxysteroid dehydrogenase as well as 2-D gel analysis of StAR. The treatment decreased the luteal PBR mRNA expression at all time periods starting at 4 h compared with that in corresponding sham controls. GnRH-Ag also reduced, in the CL, the PBR protein/ligand binding, the StAR protein and P450 scc protein and its activity as early as 8 h after the treatment and they remained low compared with those in corresponding sham controls. The data from 2-D gel studies suggest that the majority of the decrease in StAR protein appears to be in the phosphorylated forms of StAR. Thus, we have demonstrated, for the first time, the presence of PBR and StAR in the pregnant rat CL and that the coordinated suppression of these proteins involved in the mitochondrial cholesterol transport along with P450 scc by GnRH-Ag leads to reduced ovarian steroidogenesis.
J Mol Endocrinol 1999 Feb
PMID:GnRH agonist treatment decreases progesterone synthesis, luteal peripheral benzodiazepine receptor mRNA, ligand binding and steroidogenic acute regulatory protein expression during pregnancy. 992 79


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