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

In recent years, the enzymes which are involved in the formation of DHT in steroid target tissues have been well investigated, however, enzymes responsible for the catabolism and elimination of steroids in these tissues, in particular the uridine diphospho-glucuronosyltransferase (UGT) family of enzymes, have received much less attention. We have recently demonstrated that human and monkey are unique in having high plasma levels of C19 steroid glucuronides. These circulating conjugates have been proposed to reflect the peripheral conversion of adrenal and gonadal C19 steroids to potent androgens, especially DHT. In humans, the presence of steroid UGT activities is found in the liver and several extrahepatic tissues including the prostate, mammary gland and ovary. In addition, UGT activities were observed in breast and prostate tumor cell lines such as MCF-7 and LNCaP, respectively. In agreement with the presence of steroid conjugating enzymes in extrahepatic tissues, UGT cDNA clones, which encode steroid conjugating proteins, have been isolated from libraries constructed from human and monkey prostate mRNA. The presence of UGT transcripts and proteins in extrahepatic tissues in both species, as determined by Northern blot, ribonuclease protection, specific RT-PCR, in situ hybridization, Western blot and immunocytochemistry analysis, indicate the relevance of steroid glucuronidation in tissues other than the liver. Knowing that both the human prostate and the human prostate cancer LNCaP cell line express steroid metabolizing proteins, including UGT enzymes, regulation of UGT mRNA and protein levels, as well as promoter activity was studied in these cells. The results demonstrate a differential regulation between the two highly related isoforms UGT2B15 and UGT2B17, where only the expression of UGT2B17 was affected following treatments of LNCaP cells with androgens, growth factors or cytokines. Steroid conjugation by UGT enzymes is potentially involved in hormone inactivation in steroid target tissues, thus modifications in UGT expression levels may influence hormonal responses.
J Steroid Biochem Mol Biol
PMID:Characterization of UDP-glucuronosyltransferases active on steroid hormones. 1041 20

We previously reported lymphocyte expression of genes encoding enzymes required for steroid metabolism; however, only 17beta-HSD and 5alpha-reductase showed significant enzyme activity. We now investigate regulation of lymphocyte expression for genes encoding 17beta-HSD and 5alpha-reductase. Cultured human T and B lymphoid cell lines and peripheral blood mononuclear cells were treated with known regulators of steroidogenic gene expression including forskolin, PMA, ionomycin, various steroids, interleukin (IL)-4, and IL-6. Treatment with 10 or 50 microM forskolin resulted in a 20-60% reduction of expression for HSD17B1 (encoding 17beta-HSD I) in T and B lymphoid cell lines and peripheral blood mononuclear cells, although such a change was not observed in the expression of SRD5A1 (encoding 5alpha-reductase I). No significant changes were found when cells were treated for 24 h with various concentrations of PMA or ionomycin. Incubation with 10(-9) to 10(-7) M androstenedione or estradiol increased expression of HSD17B1, while testosterone decreased the expression of this gene. SRD5A1 expression was increased in the presence of 5alpha-DHT although no consistent changes were observed when the cells were treated with testosterone. Other steroids, including dexamethasone, progesterone, and 6-hydroxypregnanolone, produced no effects on expression of either HSD17B1 or SRD5A1. Treatment with 0.1-10 ng/ml of IL-4 or IL-6 also did not effect significant changes in gene expression. These data implicate the involvement of the cAMP-protein kinase signal transduction pathway in regulating lymphocyte expression of HSD17B1. Furthermore, it appears that lymphocyte HSD17B1 and SRD5A1 are regulated to some extent by specific steroids.
Mol Genet Metab 1999 Nov
PMID:Regulation of HSD17B1 and SRD5A1 in lymphocytes. 1056 69

CNNT. There was a good correlation between bioactivity and binding affinity to AR for the 7alpha-substituted androgens compared to T. In contrast, relative to their binding affinity to AR, the androgenic potency of DHT and 19-NT was lower compared to T. The reason for the lower in vivo androgenic activity of 19-NT is attributable to its enzymatic conversion to 5alpha-reduced-19-NT in the prostate. In the case of DHT, the lower bioactivity could be attributed to its faster metabolic clearance rate relative to T. The correlation was further investigated in vitro by co-transfection of rat ARcDNA expression plasmid and a reporter plasmid encoding the chloramphenicol acetyl transferase (CAT) gene driven by an androgen inducible promoter into CV-1 cells. All the androgens led to a dose-dependent increase in the CAT activity. MENT was found to be the most potent followed by DHT, 19-NT, T, and CNNT. The specificity of the androgenic response was confirmed by its inhibition with hydroxyflutamide, an antiandrogen. Thus, there was a good correlation between binding affinity and in vitro bioactivity in the transient transfection assay for the androgens. This suggests that the in vivo bioactivity of androgens could be influenced not only by binding affinity to receptors but also by factors such as absorption, binding to serum proteins and metabolism. However, the high potency of MENT is primarily related to its higher affinity to AR.
J Steroid Biochem Mol Biol 1999 Dec 31
PMID:7alpha-methyl-19-nortestosterone, a synthetic androgen with high potency: structure-activity comparisons with other androgens. 1070 10

We developed a new stable prostatic cell line expressing the human androgen receptor (AR) and the AR-responsive reporter gene to generate a powerful tool for investigating androgen action and for rapid screening of agonists and antagonists. The AR-deficient PC-3 cells were stably transfected with pSG(5)-puro-hAR and pMMTV-neo-Luc. After selection with puromycin and neomycin, one highly inducible clone was isolated and named PALM, for PC-3-Androgen receptor-Luciferase-MMTV. The expression of hAR was confirmed by western blot and steroid-binding assays on the whole cells. The transcriptional activity of the clone was measured after incubation of cells with increasing concentrations of synthetic R1881 or natural androgens (DHT and testosterone). The three agonists had the same maximal activity at 0.1 microM and the fold induction was equal to 20. The agonist and antagonist activities of the steroidal antiandrogens (cyproterone acetate and RU2956) and the non-steroidal antiandrogens (nilutamide, bicalutamide, inocoterone and hydroxyflutamide) measured with the PALM cells were in good correlation with the results obtained with transiently transfected cells. The selectivity in steroid transactivation was demonstrated with estradiol, progesterone, cortisol, dexamethasone and aldosterone. Spironolactone and RU486 showed partial agonist and antagonist activities, whereas R5020 presented only a partial antagonist activity. We here demonstrate that this stable transfectant provides an accurate tool for studying wild-type human AR activation and its regulation by androgens and antiandrogens in a human prostatic epithelial cell, which is routinely available and remains androgen-responsive in vitro.
Mol Cell Endocrinol 2000 Feb 25
PMID:A stable prostatic bioluminescent cell line to investigate androgen and antiandrogen effects. 1071 37

Degeneration of serotonergic fibers in the rat striatum was produced by local administration of the serotonergic neurotoxin 5, 7-dihydroxytryptamine (5,7-DHT) or the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)), which is also toxic to serotonergic neurons. One week before neurotoxin administration, fibroblasts engineered to express the human BDNF gene were grafted into the mesencephalon, dorsal to the substantia nigra. Rats implanted with fibroblasts expressing the LacZ gene were used as controls, as well as sham-operated animals (not injected with any neurotoxin). After a survival period of 1 week, the serotonergic innervation of the striatum was assessed by measuring serotonin (5-HT) content and by immunohistochemical detection of 5-HT positive fibers. BDNF-producing cells prevented the striatal 5-HT loss induced by local administration of either 5,7-DHT or MPP(+), as well as the striatal dopamine (DA) loss induced by the latter neurotoxin. Grafting of fibroblasts carrying the BDNF or the Lac-Z gene did not modify striatal 5-HT or DA content in sham-operated animals. In 5, 7-DHT-lesioned rats, implanted or not with control Lac-Z fibroblasts, a striking reduction in the density of 5-HT immunoreactive fibers was observed. By contrast, the density of 5-HT fibers was similar in rats implanted with BDNF-producing fibroblasts as compared to sham-operated controls. The protective effect of BDNF on the damage to serotonergic terminals induced by the two neurotoxins suggests the interest of this neurotrophin in the treatment of behavioral disorders associated to neurodegenerative diseases.
Brain Res Mol Brain Res 2000 Mar 29
PMID:Implanted BDNF-producing fibroblasts prevent neurotoxin-induced serotonergic denervation in the rat striatum. 1076 6

17beta-Hydroxysteroid dehydrogenase (17beta-HSD) type 5 has been cloned from human prostate and is identical to type 2 3alpha-HSD and is a member of the aldo-keto reductase (AKR) superfamily; it is formally AKR1C3. In vitro the homogeneous recombinant enzyme expressed in Escherichia coli functions as a 3-keto-, 17-keto- and 20-ketosteroid reductase and as a 3alpha-, 17beta- and 20alpha-hydroxysteroid oxidase. The enzyme will reduce 5alpha-DHT, Delta(4)-androstene-3,17-dione, estrone and progesterone to produce 3alpha-androstanediol, testosterone, 17beta-estradiol and 20alpha-hydroxprogesterone, respectively. It will also oxidize 3alpha-androstanediol, testosterone, 17beta-estradiol and 20alpha-hydroxyprogesterone to produce 5alpha-androstane-3,17-dione, Delta(4)-androstene-3,17-dione, and progesterone, respectively. Many of these properties are shared by the related AKR1C1, AKR1C2 and AKR1C4 isoforms. RT-PCR shows that AKR1C3 is dominantly expressed in the human prostate and mammary gland. Examination of k(cat)/K(m) for these reactions indicates that as a reductase it prefers 5alpha-dihydrotestosterone and 5alpha-androstane-3,17-dione as substrates to Delta(4)-androstene-3,17-dione, suggesting that in the prostate it favors the formation of inactive androgens. Its concerted reductase activity may, however, lead to a pro-estrogenic state in the breast since it will convert estrone to 17beta-estradiol; convert Delta(4)-androstene-3,17-dione to testosterone (which can be aromatized to 17beta-estradiol); and it will reduce progesterone to its inactive metabolite 20alpha-hydroxyprogesterone. Drawing on detailed structure-function analysis of the related rat 3alpha-HSD (AKR1C9), which shares 69% sequence identity with AKR1C3, it is predicted that AKR1C3 catalyzes an ordered bi bi mechanism, that the rate determining step is k(chem), and that an oxyanion prevails in the transition state. Based on these relationships steroidal-based inhibitors that compete with the steroid product would be desirable since they would act as uncompetitive inhibitors. With regards to transition state analogs steroid carboxylates and pyrazoles may be preferred while 3alpha, 17beta or 20alpha-spiro-oxiranes may act as mechanism-based inactivators.
Mol Cell Endocrinol 2001 Jan 22
PMID:Structure-function aspects and inhibitor design of type 5 17beta-hydroxysteroid dehydrogenase (AKR1C3). 1116 22

Cultured human dermal papilla cells are useful for studying the androgen-dependent growth of hair follicles. We cloned the human homolog of FAR-17a, a gene identified from the hamster flank organ as one of the androgen inducible genes, by degenerative PCR and human dermal papilla cDNA library screening. We isolated a novel cDNA clone, designated as AIG1 (Androgen-inducible Gene 1), whose expression was found to be inducible by androgen. AIG1 cDNA consists of 1,398 nucleotides in length, which encodes a protein of 238 amino acids (27 kDa). The deduced protein sequence showed 35% overall homology with FAR-17a. RT-PCR of human dermal papilla cDNA revealed two mRNA transcripts, which differed by 156 nucleotides. This results in an in-frame deletion of 52 amino acids. A computer analysis of hydropathy indicated five hydrophobic domains are present in the large protein sequence, while four hydrophobic portions are in the smaller protein sequence. In a Northern blot analysis, the major 1.5 kb and minor 1.2 kb bands of AIG1 mRNA were detected. AIG1 mRNA was expressed at a relatively high level in the heart, ovary, testis, liver, and kidney. However, they were expressed at a low level in the spleen, prostate, brain, skeletal muscle, pancreas, small intestine, and colon. When dermal sheath cells were stimulated with DHT, the level of AIG1 mRNA expression was increased at 30 ng/ml. The level of expression was higher in males than females. In this study, we cloned and initially characterized AIG1. Further study will be needed to understand the functions of AIG1 in the androgen-regulated hair cycle.
Mol Cells 2001 Feb 28
PMID:Cloning of androgen-inducible gene 1 (AIG1) from human dermal papilla cells. 1126 18

Plasma gonadotropin II (GTH II) concentrations were significantly higher (approx. 15-20-fold) in estradiol-17beta (E(2)) treated (1.0 microg or 2.5 microg g(-1) body weight) female black porgy from days 4 to 12 compared with the control. E(2) (1 microg g(-1) wt.) had a stronger stimulation on plasma GTH II in early recrudescent phase (low GSI) males (11-fold) than in high GSI and late spermiating males (2.6-fold, P< 0.05). No effect of androgens (testosterone, T; 5alpha-dihydrotestosterone, DHT) on plasma GTH II levels was observed either sex. The levels of plasma GTH II were stimulated in 1,4,6-androstatriene-3,17-dione (ATD, 1 microg g(-1), 2 microg g(-1) body wt.) and fadrozole-treated (1 microg g(-1), 3 microg g(-1) body wt.) groups compared to control. Tamoxifen (1 microg g(-1), 3 microg g(-1) body wt.) but not enclomiphene could stimulate high GTH II levels in plasma. In another experiment of ATD in combination with T, T treatment further attenuated the ATD stimulation of plasma GTH II levels. We concluded that GTH II secretion is positively regulated by an estrogen-specific effect in female and male black porgy. Gonadal stage had significant effects on the responsiveness of GTH II to E(2) stimulation in males. A negative aromatase-dependent feedback control of plasma GTH II levels was also suggested in the protandrous black porgy, Acanthopagrus schlegeli.
Comp Biochem Physiol B Biochem Mol Biol 2001 Jun
PMID:Regulation of plasma gonadotropin II secretion by sex steroids, aromatase inhibitors, and antiestrogens in the protandrous black porgy, Acanthopagrus schlegeli Bleeker. 1139 74

Aromatase is possibly involved in male brain sexual differentiation. Aim of these experiments was to evaluate the role of testosterone (T) and of DHT, in the regulation of aromatase expression and activity. The experiments were done utilizing rat primary cultures of hypothalamic neurons from 16-day old embryos sex-screened by SRY gene. Aromatase expression was assessed semiquantitatively by RT-PCR using a neuronal marker (MAP2c) as coamplification product; enzymatic activity was estimated by the 3H(2)O method. The results indicate that (1) cultured neurons possess a functional aromatase, which increases significantly during a 5-days culture period; (2) neurons from males possess a higher expression and activity of the enzyme than females; (3) androgens negatively control expression/activity of aromatase in males, DHT is more active than T; (4) on the contrary, in females T produces a small stimulation of aromatase expression, but not of activity (DHT has produced inconsistent results). The results obtained in this model indicate that T does not stimulate aromatase; therefore, it is not responsible for triggering the perinatal enzymatic peak, nor for the sexual dimorphic aromatase expression. A model is proposed in which DHT might induce, at least in males, the descending phase of the aromatase peak.
Mol Cell Endocrinol 2001 Jun 10
PMID:Aromatase expression and activity in male and female cultured rat hypothalamic neurons: effect of androgens. 1140 88

Inhibitors of human 5alpha-reductase type II are promising drug candidates for the treatment of benign prostatic hyperplasia which is associated with high prostatic DHT levels. In this study we describe the evaluation of potential inhibitors in a new cell assay. First a plasmid (pRcCMV-5alphaII) for the expression of human 5alpha-reductase type II was constructed by the use of the vector pRcCMV and transfected into the African green monkey fibroblast-like cell line COS1. By selection with G418 sulfate, ten COS1 single cell clones were obtained of which three stably exhibited high 5alpha-reductase activity. One single cell clone (COS1-5alphaIIST) was selected for further investigations. By Southern blot analysis, fluorescence in situ hybridization (FISH) and comparative PCR experiments it turned out that the expression plasmid pRcCMV-5alphaII has been integrated into the chromosome, resulting in a long-term stable expression of the foreign 5alpha-reductase gene. The newly established cell line was used for testing novel compounds on their inhibitory effect on human 5alpha-reductase type II. Using this whole cell assay, inhibitors with IC(50) values in the nanomolar range could be identified.
J Steroid Biochem Mol Biol 2001 Sep
PMID:Stable expression of human 5alpha-reductase type II in COS1 cells due to chromosomal gene integration: a novel tool for inhibitor identification. 1159 8


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>