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)

To determine possible cellular mechanisms governing androgen action in the brain, we examined the hormonal regulation of androgen receptor (AR) mRNA in neural tissues by Northern blot hybridization and RNase protection analysis. While a single hybridizable species of AR mRNA of approximately 11 kb was found in the anterior pituitary gland (AP) and ventral prostate gland (VP), an additional species of AR mRNA, approximately 2 kb smaller, was revealed in neural tissues. Furthermore, in these neural tissues, hormonal regulation of the two species of mRNA was coordinated; long-term castration increased levels of both forms, while testosterone replacement reduced them. The same pattern of regulation was observed for the single 11 kb form in the AP. An RNase protection assay was validated and utilized to quantitatively analyze the hormonal regulation of AR mRNA. Castration (4 days) resulted in significantly increased AR mRNA in the AP and hypothalamic-preoptic area, but not the amygdala, which subsequent administration of dihydrotestosterone (DHT; 1 day; 2 mg/animal) significantly decreased. In the AP, administration of estradiol benzoate (EB) for 1 or 5 days also reversed this effect. However, EB treatment increased the amount of total RNA isolated per gland. Consequently, when the data are normalized to RNA content per gland, 5 days of EB treatment resulted in a significant increase in AR mRNA content. These findings suggest that in contrast to the AP and VP, two forms of androgen receptor mRNA exist in the brain. In addition, there appears to be tissue and hormone specific regulation of AR mRNA.
Brain Res Mol Brain Res 1993 Jul
PMID:Hormonal regulation of androgen receptor mRNA in the brain and anterior pituitary gland of the male rat. 836 43

Repeated high doses of d-fenfluramine (dF; 10 mg/kg, i.p. twice daily for 4 days) markedly reduced serotonin (5-HT) concentrations in the hippocampus and striatum of rat brain up to 1 month after treatment, while tryptophan hydroxylase (TPH) levels were reduced only in the hippocampus 5 days after injection. Unlike dF, an intracerebroventricular (i.c.v.) injection of 5,7-dihydroxytryptamine (5,7-DHT 150 micrograms/20 microliters) induced a marked and long-lasting reduction of 5-HT and TPH in both brain regions. Thirty days after injection, 5,7-DHT, but not dF, markedly reduced the number of labelled neurons in the dorsal and ventral regions of the nucleus raphe dorsalis (NRD) and raised the levels of TPH mRNA in the spared neurons at all times examined. TPH mRNA levels were raised 5 and 15 days after dF treatment in the NDR suggesting that changes in the TPH gene expression or transcript stability result following 5-HT depletion. These data are in agreement with the suggestion that 5,7-DHT damages 5-HT nerve terminals and perikarya, but leave unanswered the question of the mechanism of the long-lasting reduction of 5-HT levels caused by high, repeated doses of dF.
Brain Res Mol Brain Res 1993 Aug
PMID:Effect of d-fenfluramine and 5,7-dihydroxytryptamine on the levels of tryptophan hydroxylase and its mRNA in rat brain. 841 72

A 56 kDa protein expressed in human genital skin fibroblasts was first identified by independent laboratories on the basis of its specific expression in androgen target cells and its ability to covalently bind androgenic affinity ligands. Recently, immunoscreening of a cDNA library with antisera directed against this protein resulted in the isolation of a partial cDNA clone identical to human cytosolic aldehyde dehydrogenase (ALDH1). We report here the preparation of a full-length cDNA encoding ALDH1 from human genital fibroblasts. Translation of the encoded protein in a cell-free system yields a 56 kDa product that can be covalently radiolabeled with [3H]dihydrotestosterone 17 beta-bromoacetate (DHT-BA). Expression of the full-length clone in mammalian cells also results in expression of a 56 kDa DHT-BA binding protein. The covalent binding of DHT-BA by ALDH1 is an intrinsic property of the enzyme and is not dependent on androgen receptor expression.
Mol Cell Endocrinol 1993 Feb
PMID:An androgenic affinity ligand covalently binds to cytosolic aldehyde dehydrogenase from human genital skin fibroblasts. 847 48

The isoenzymes of the 3 beta-hydroxysteroid dehydrogenase/5-ene-4-ene-isomerase (3 beta-HSD) gene family catalyse the transformation of all 5-ene-3 beta-hydroxysteroids into the corresponding 4-ene-3-keto-steroids and are responsible for the interconversion of 3 beta-hydroxy- and 3-keto-5 alpha-androstane steroids. The two human 3 beta-HSD genes and the three related pseudogenes are located on the chromosome 1p13.1 region, close to the centromeric marker D1Z5. The 3 beta-HSD isoenzymes prefer NAD+ to NADP+ as cofactor with the exception of the rat liver type III and mouse kidney type IV, which both prefer NADPH as cofactor for their specific 3-ketosteroid reductase activity due to the presence of Tyr36 in the rat type III and of Phe36 in mouse type IV enzymes instead of Asp36 found in other 3 beta-HSD isoenzymes. The rat types I and IV, bovine and guinea pig 3 beta-HSD proteins possess an intrinsic 17 beta-HSD activity specific to 5 alpha-androstane 17 beta-ol steroids, thus suggesting that such "secondary" activity is specifically responsible for controlling the bioavailability of the active androgen DHT. To elucidate the molecular basis of classical form of 3 beta-HSD deficiency, the structures of the types I and II 3 beta-HSD genes in 12 male pseudohermaphrodite 3 beta-HSD deficient patients as well as in four female patients were analyzed. The 14 different point mutations characterized were all detected in the type II 3 beta-HSD gene, which is the gene predominantly expressed in the adrenals and gonads, while no mutation was detected in the type I 3 beta-HSD gene predominantly expressed in the placenta and peripheral tissues. The mutant type II 3 beta-HSD enzymes carrying mutations detected in patients affected by the salt-losing form exhibit no detectable activity in intact transfected cells, at the exception of L108W and P186L proteins, which have some residual activity (approximately 1%). Mutations found in nonsalt-loser patients have some residual activity ranging from approximately 1 to approximately 10% compared to the wild-type enzyme. Characterization of mutant proteins provides unique information on the structure-function relationships of the 3 beta-HSD superfamily.
J Steroid Biochem Mol Biol 1995 Dec
PMID:Structure-function relationships and molecular genetics of the 3 beta-hydroxysteroid dehydrogenase gene family. 854 74

The administration of the anorexigenic drug d,l-fenfluramine (Ponderax) to laboratory animals results in a dose-dependent reduction in presynaptically located serotonergic reuptake transporter protein. This long-term effect may represent an altered mechanism of synthesis of the transporter (downregulation). Alternatively, fenfluramine may destroy the serotonergic terminals on which 5-HT transporters are located. To distinguish between these two alternatives, we applied an assay of neurotransmitter-specific nerve endings (alpha) to brain tissue from two animal models of reduced 5-HT transporter density. In Model 1, serotonergic nerve terminals were destroyed (rats received 5,7-dihydroxytryptamine [5,7-DHT] intracisternally); in Model 2, there was a loss of 5-HT transporter per se on otherwise intact serotonergic nerve terminals. The manner in which alpha declined as transporter density was decreased (reducing Vmax values) in animal Models 1 and 2 was found to be significantly different. In rats treated with fenfluramine, the association between 5-HT transporter density and alpha was the same as in the neurotoxic model.
Mol Neurobiol
PMID:The nature of d,l-fenfluramine-induced 5-HT reuptake transporter loss in rats. 856 60

Sequence determinants for the importation of tRNAs into the mitochondrion of Leishmania tarentolae in vivo were investigated. tRNA(Ile)(UAU) is exclusively localized within the mitochondrion and tRNA(Gln)(CUG) exclusively in the cytosol (Lye LF, Chen DHT, Suyama Y, 1993, Mol Biochem Parasitol 58:233-246; Shi X, Chen DHT, Suyama Y, 1994, Mol Biochem Parasitol 65:23-37). L. tarentolae cells were transfected with plasmids encoding either tRNA(Ile) or tRNA (Gln) that were tagged with altered sequences in the D loop, permitting discrimination from the endogenous tRNAs. Primer extension analysis was used to show that the plasmid-encoded genes were expressed and that the tagged tRNAs showed a similar intracellular localization as the endogenous tRNAs. Exchange or deletion of the 5'-flanking genomic sequences had no effect on the expression or mitochondrial localization of the tagged tRNA(Ile) or on the expression or cytosolic localization of the tagged tRNA(Gln), suggesting that the signals for importation are localized within the tRNA itself. Swapping the D loop+stem from the exclusively cytosolic tRNA(Gln) with that from the tRNA(Ile) produced a partial mitochondrial localization of the plasmid-expressed mutated tRNA(Gln). However, D loop exchange did not eliminate the mitochondrial localization of the plasmid-expressed mutated tRNA(Ile), suggesting that tertiary structure or additional sequence elements may be involved in the importation signal.
 ...
PMID:Sequence-dependent in vivo importation of tRNAs into the mitochondrion of Leishmania tarentolae. 866 10

This paper summarizes the most recent data obtained in the authors' laboratory on the metabolism of testosterone and progesterone in neurons and in the glia. 1. The activities of 5 alpha-reductase (the enzyme that converts testosterone into dihydrotestosterone; DHT) and of 3 alpha-hydroxy steroid dehydrogenase (the enzyme that converts DHT into 5 alpha-androstane-3 alpha, 17 beta-diol; 3 alpha-diol) were first evaluated in primary cultures of neurons, oligodendrocytes, and type-1 and type-2 astrocytes, obtained from the fetal or neonatal rat brain. The formation of DHT and 3 alpha-diol was evaluated incubating the different cultures with labeled testosterone or labeled DHT as substrates. The results obtained indicate that the formation of DHT takes place preferentially in neurons; however, also type-2 astrocytes and oligodendrocytes possess considerable 5 alpha-reductase activity. A completely different localization was observed for 3 alpha-hydroxysteroid dehydrogenase; the formation of 3 alpha-diol appears to be prevalently, if not exclusively, present in type-1 astrocytes; 3 alpha-diol is formed in very low yields by neurons, type-2 astrocytes, and oligodendrocytes. Moreover, the results indicate that, in type 1 astrocytes, both 5 alpha-reductase and 3 alpha-HSD are stimulated by coculture with neurons and by the addition of neuron-conditioned medium, suggesting that secretory products released by neurons might intervene in the control of glial cell function. 2. Subsequently it was shown that, similarly to what happens when testosterone is used as the substrate, 5 alpha-reductase, which metabolizes progesterone into 5 alpha-pregnane-3,20-dione, (DHP), shows a significantly higher activity in neurons than in glial cells; however, also type-1 and type-2 astrocytes as well as oligodendrocytes possess some ability to 5 alpha-reduce progesterone. On the contrary, 3 alpha-hydroxysteroid dehydrogenase, the enzyme which converts DHP into 5 alpha-pregnane-3 alpha-ol-20-one (THP), appears to be present mainly in type-1 astrocytes; much lower levels of this enzyme are present in neurons and in type-2 astrocytes. At variance with the previous results obtained using androgens as precursors, oligodendrocytes show considerable 3 alpha-hydroxysteroid dehydrogenase activity, even if this is statistically lowe than that present in type-1 astrocytes. The existence of isoenzymatic forms of the enzymes involved in androgen and progesterone metabolism is discussed.
Cell Mol Neurobiol 1996 Jun
PMID:Testosterone and progesterone metabolism in the central nervous system: cellular localization and mechanism of control of the enzymes involved. 881 96

Finasteride is a potent 5 alpha-reductase inhibitor which has proven useful in the clinical management of benign prostatic hyperplasia. To determine a potential mode of action for finasteride in prostatic cell proliferation, we have studied the incorporation of [3H]-thymidine into the DNA of cultured epithelial and stromal cells from normal and hyperplastic human prostates. The effects of short treatment with 10(-9) M and 10(-6) M finasteride (48 hrs.) on the incorporation of labelled thymidine were studied. A significant effect of finasteride on prostatic cell proliferation was observed at 10(-6) M for both epithelium and stroma from normal prostate: the rate of thymidine incorporation decreased to 80 +/- 3% (p < 0.001) and 55 +/- 10% (p < 0.01), respectively, compared to the control cells. As observed for normal prostates, this rate of thymidine incorporation was less for hyperplastic epithelium (70 +/- 4%, p < 0.001) than that observed for the hyperplastic stroma (74 +/- 4%, p < 0.01). These data clearly demonstrate that the reduction of the prostate volume observed in BPH treatment by finasteride is partly due to an inhibition of cell proliferation. However, the absence of complete inhibition of cell proliferation at 10(-6) M, a concentration known to strongly inhibit the 5 alpha-reductase activity, supports the hypothesis that factors other than DHT are necessary to induce prostatic cell proliferation.
Cell Mol Biol (Noisy-le-grand) 1996 Jun
PMID:Effect of finasteride (Proscar) on the proliferation of cultured epithelial and stromal cells from normal and hyperplastic human prostates. 882 6

Androgen-dependent growth of prostate tissue has been well documented. An additional prerequisite for cellular growth is the accumulation of ribosomes. It is thus reasonable to hypothesize that ribosomal DNA (rDNA) transcription in prostate tissue must be stimulated by androgen either directly or indirectly. This hypothesis was tested using both LNCaP cells, an androgen-dependent tissue culture line and in a rat animal model. Nuclear run-on assays confirmed that the administration of DHT to LNCaP cells resulted in a two- to three-fold increase in the rate of rRNA synthesis when compared to cells maintained in the absence of androgen. Enzymatic analysis and Western blots were carried out to measure the amount (activity and mass) of RNA polymerase I in DHT treated LNCaP cells. These assays demonstrated that neither the catalytic activity of RNA polymerase I nor the amount of the enzyme varied in response to DHT. However, Western blots revealed that the amount of the auxiliary RNA polymerase I transcription factor UBF, was significantly increased (two- to three-fold) in cells grown in the presence of DHT. Similar experiments were carried out with prostatic tissue obtained from orchiectomized rats maintained on either placebo or testosterone pellets. In this model, both the catalytic activity as well as the amount of RNA polymerase I protein decreased. However, in agreement with the tissue culture model, UBF protein decreased in prostates from orchiectomized rats and was maintained in animals supplemented with testosterone. These lines of evidence are consistent with the hypothesis that androgens stimulate rRNA synthesis by increasing the quantities of the components of the rDNA transcription system.
J Steroid Biochem Mol Biol 1996 Dec
PMID:Androgen regulation of ribosomal RNA synthesis in LNCaP cells and rat prostate. 901 Mar 48

Homogenates of histologically normal human testis from three men were incubated separately with pregnenolone, 16-dehydropregnenolone, 5alpha-pregnane-3,20-dione, 3beta-hydroxy-5alpha-pregnan-20-one and androsta-5,16-dien-3beta-ol (androstadienol) in the presence of NADPH in a study of androst-16-ene and androgen biosynthesis. After the addition of internal standards and initial extraction and purification, metabolites were identified using gas chromatography-mass spectrometry (GC-MS) and monitoring selectively for three principal ions in each case at the appropriate GC retention time. Quantification was achieved by comparison with calibration lines for authentic steroids, together with the appropriate internal standards, prepared by monitoring three ion fragments for each analyte. In all experiments, androstadienol was found to be the major androst-16-ene metabolite of pregnenolone (seven times the control, i.e. endogenous, quantity; 19.8 +/- 3 ng/100 mg homogenate protein, mean +/- SEM, n = 9). Pregnenolone was also converted to androsta-4,16-dien-3-one (androstadienone) with three times the endogenous quantity (44 +/- 10 ng/100 mg homogenate protein, mean +/- SEM, n = 9) being formed. The formation of testosterone occurred only in trace amounts in the incubations of testis taken from one man (a 69-yr-old) but appreciable yields (six times endogenous levels 90 +/- 7 ng/100 mg homogenate protein, mean +/- SEM, n = 9) were found with testes from two younger men. Only traces of 5alpha-dihydrotestosterone were detected. Using androstadienol as the substrate, androstadienone was shown to be the major metabolite (approximately 10 times greater than control incubations) together with 5alpha-androst-16-en-3alpha- and 3beta-ols at approximately twice the endogenous quantities (5 ng/100 mg homogenate protein). In some incubations with androstadienol, 5alpha-androst-16-en-3-one (5alpha-androstenone) was formed (32 +/- 1 ng/100 mg homogenate protein/h; mean +/- SEM, n = 3); surprisingly, no endogenous 5alpha-androstenone could be detected. No evidence was obtained for the production of testosterone or 5alpha-DHT from androstadienol. Using cytosolic fractions of human testis, specific (displaceable) binding of 5alpha-androstenone was determined, with binding sites of approximately 200 fmol/mg tissue and a Ka of approximately 8 nmol/l.
J Steroid Biochem Mol Biol 1997 Jan
PMID:Use of gas chromatographic-mass spectrometric techniques in studies of androst-16-ene and androgen biosynthesis in human testis; cytosolic specific binding of 5alpha-androst-16-en-3-one. 918 68


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