Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytosol from human benign hyperplastic and carcinomatous prostatic tissue has been shown to contain a progestin receptor with a dissociation constant of approximately 10(-9) M. The receptor was measured using 3H-labeled R 5020 (17 alpha, 21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione) as ligand. Progesterone, cyproterone acetate, and R 1881 (methyltrienolone) were efficient competitors to R 5020 for binding sites on the receptor whereas testosterone, 5 alpha--dihydrotestosterone, estradiol, cortisol, and several hydroxylated and saturated derivatives of progesterone did not compete. The [3H]R 2020-receptor-complex had a sedimentation coefficient of approximately 4 S, an isoelectric point of approximately 5, was heat-labile, and was destroyed by treatment with trypsin but not with deoxyribonuclease or ribonuclease. Seventeen of 21 patients with benign prostatic hyperplasia and three patients with prostatic carcinoma had 1 to 40 fmoles of specific R 5020-binding sites per mg of cytosol protein. One sample of normal prostatic tissue did not contain significant amounts of progesting receptor. Tissue specimens removed by transvesical adenoma enucleation displayed a larger number of specific R 5020-binding sites than electroresected specimens. The progestin receptor in hyperplastic prostate may be involved in the mechanism of the action of progestins used in the medical treatment of benign prostatic hyperplasia. Quantitation of progestin receptor in cancer of the prostate may form part of the basis of a predictive test program for endocrine therapy of prostatic malignancy.
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PMID:Demonstration of a progestin receptor in human benign prostatic hyperplasia and prostatic carcinoma. 7 18

In order to characterize the uterine progesterone-binding proteins of oestrogen-primed and unprimed, ovariectomized immature and adult golden hamsters, cytosols were incubated with [3H]progesterone and/or other steroids and analyzed by sucrose-glycerol density gradient ultracentrifugation. Progesterone-binding components with sedimentation coefficients of 7S and 4.5S were found in the uterine cytosols, but not in the cytosols from the hypothalamus, pituitary, diaphragm, or small intestine. Oestradiol-17beta markedly elevated the level of 7S uterine receptor and this increase appeared to be due to new receptor synthesis, since actinomycin D and cycloheximide blocked this response. Fifty to 100 mug of oestradiol-17beta per kg body weight was found to promote a maximum increase in the 7S macromolecular component. The 7S receptor showed a tendency to saturate at 1 X 10(-7) M [1,2-3H]progesterone, indicating limited capacity. At a molar ratio of 100:1, unlabeled progesterone competed effectively for 7S and 4,5S [3H]progesterone binding, whereas 5alpha-pregnane-3,20-dione, oestradiol-17beta and testosterone did not. Moreover, [1,2-3H]cortisol and [1,2-3H]corticosterone did not bind to the 7S receptor, implying steroid specificity. CI-628, a non-steroid oestrogen antagonist, completely prevented [6,7-3H]oestradiol-17beta binding to its 8.5S uterine cytosol receptor, but was entirely without effect on 7S and 4.5S [3H]progesterone binding. Pronase, but not DNase or RNase, abolished 7S and 4.5S progesterone binding, suggesting that the binders are at least in part protein. Protamine sulphate and p-hydroxymercuribenzoate also obliterated 7S binding, implying that this receptor may be an acidic protein which contains sulfhydryl groups that are necessary for progesterone binding.
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PMID:Oestrogen-inducible uterine progesterone receptors. characteristics in the ovariectomized immature and adult hamster. 17 Jul 71

Progesterone receptors (PR) are the strongest predictors of response to hormone therapy in metastatic breast cancer, while PR and the DNA indices of cell ploidy and percentage of S phase are useful prognostic indicators in early stage breast cancer. We have developed a flow cytometry method to measure PR and DNA indices simultaneously using two aneuploid breast cancer cell lines--PR-positive T47D cells and PR-negative MDA-231 cells. Cells were pretreated with the progestin 17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione, harvested, counted, fixed with paraformaldehyde, and permeabilized with Triton X-100. To measure total PR, cells were first exposed to a mixture of the mouse anti-PR monoclonal antibody AB-52, which binds both Protein A and Protein B of human PR, and to monoclonal antibody B-30 or B-64, which bind only Protein B. Then the cells were treated with fluorescein isothiocyanate-conjugated goat anti-mouse second antibody to produce a green fluorescence signal corresponding to PR. To measure nonspecific binding, cells were treated with mouse IgG1 as the first antibody in a parallel incubation. Specific immunoassayable PR is the difference between total and nonspecific binding. Following the antibodies, the cells were treated with RNase A and propidium iodide to give a red fluorescence signal corresponding to DNA content. Red and green fluorescence per cell was then quantified by flow cytometry. This method gives a strong specific signal for PR in several T47D cell sublines but no specific binding in MDA-231 cells. Progestin treatment led to apparent increases in PR. The proportion of cells in the G0-G1, S, and G2-M phases of the cell cycle was determined from DNA histograms and showed that both cell lines were hyperdiploid. The simultaneous flow cytometry method allowed assignment of relative PR levels in subsets of cells segregated by their DNA content. In T47D cells, PR were present throughout the cell cycle, and levels doubled in G2 and mitosis.
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PMID:Simultaneous measurement of progesterone receptors and DNA indices by flow cytometry: characterization of an assay in breast cancer cell lines. 273 33

Progesterone-specific binding components were detected in the cytosol fraction of enlarged oviducts from estrogen (diethylstilbestrol)-primed immature Japanese quail (Coturnix coturnix japonica) females by several techniques using [3H]promegestone. The oviduct as a target tissue of progesterone is the most efficient in [3H]promegestone binding, and muscle and intestine as nontarget tissues and plasma are less efficient as expected. By using [3H]promegestone for binding, the possibility of blood contamination of the oviduct may have been eliminated with the detection of a specific binding site. The participation of protein in the steroid-binding site was inferred from the destruction of the binding component by protease, but not by RNase or DNase. The interaction with [3H]promegestone in low salt conditions has a high affinity (Kd 0.69 nM) and low capacity (the number of binding sites per milligram of protein is about 1.3 pmol). Six unlabeled steroids were tested as competitors for binding to [3H]promegestone in vitro. Progesterone-like steroids competed specifically with [3H]promegestone: progesterone congruent to promegestone greater than deoxycorticosterone greater than testosterone much greater than estradiol-17 beta greater than cortisol. These chemical properties show that the progesterone binding protein present in the oviduct of estrogen-primed quail is essentially similar to that obtained from chick oviduct. In addition, heterogeneity of the [3H]promegestone binding components was shown. The binding component was eluted as an aggregate on gel (Bio-Gel A-0.5m) column chromatography in low salt conditions which reverted to two major peaks, tentatively named I (molecular weight, about 110,000) and II (about 41,000), in the presence of high salt (0.3 M KCl). The relative amounts of the two peaks differed. It was interesting that peak II of the small component was not found in the estrogen-primed chick and was a distinctive one in quail. On the other hand, both peaks were recovered with 0.3 M KCl elution on DEAE-cellulose column chromatography. These studies suggest that this binding component may function as a biological receptor for progesterone in the estrogen-enlarged oviduct, and the problems to be solved are under examination.
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PMID:Binding of progesterone with the oviduct cytosol fraction of estrogen-primed quail (Coturnix coturnix japonica). 653 58

We have recently shown that oxytocin (OT) is synthesized within human amnion, chorion, and decidua during late gestation. The levels of OT messenger ribonucleic acid (mRNA) increased around the time of parturition, suggesting that locally produced OT may play a role in this poorly understood process. In this report, we present results from investigations into the effects of estrogen and progesterone on the synthesis of OT by human chorio-decidua. Using an in vitro incubation system, estradiol at physiological concentrations more than doubled the concentration of OT mRNA. This was reflected by an increase in the amount of OT peptide secreted into the medium. The increase in OT mRNA was antagonized by tamoxifen, suggesting that the effects were estrogen receptor mediated. Progesterone had no effect on OT mRNA synthesis. Using ribonuclease protection assays, mRNAs for estrogen receptor (ER) and progesterone receptor (PR) were detected in all tissues examined. The highest levels were found in decidua, with lower amounts in chorion and very small amounts in amnion and placenta. This is the same relative tissue distribution that we previously demonstrated for OT mRNA. A single transcript was present for ER, and two transcripts were protected for PR. The concentrations of ER mRNA in chorio-decidua were 3-fold higher in tissues obtained after spontaneous labor onset than in tissues obtained from cesarean section at a similar gestational age but before labor onset. Levels of PR did not change significantly. We conclude that synthesis of OT in human chorio-decidua may be regulated in part by estrogen, and that regulation of ER levels may be an important factor modulating this effect. These data support the hypothesis of a paracrine network within human fetal membranes and decidua that may participate in regulating the timing of human birth.
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PMID:Estrogen stimulates oxytocin gene expression in human chorio-decidua. 785 22

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) cDNA was isolated from a subtracted cDNA library that selected for progesterone-induced transcripts from rat uterine stromal cells. In this study, the effects of progesterone and estradiol on the expression of HB-EGF in mature rat uterine epithelial and stromal cells have been examined. RNase protection assays and in situ hybridization demonstrated that progesterone stimulated expression of HB-EGF in rat uterine stromal cells, but repressed levels of HB-EGF mRNA in luminal and glandular epithelial cells. In contrast, estradiol treatment strongly enhanced HB-EGF expression in epithelial cells, but had no effect on mRNA levels for this growth factor in stromal cells. Progesterone treatment followed by estradiol injection stimulated HB-EGF expression in stromal cells and repressed expression in luminal and glandular epithelium. Stimulation of HB-EGF expression in stromal cells by progesterone was not inhibited by treatment with cycloheximide, demonstrating that HB-EGF mRNA expression is a primary response of stromal cells to progesterone. These results reveal that expression of HB-EGF is stimulated in epithelial and stromal cells in vivo under the same hormonal conditions that induce cell proliferation in each of these cell types and strongly suggest that HB-EGF may mediate the mitogenic effects of steroid hormones in the rat uterus.
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PMID:Heparin-binding epidermal growth factor-like growth factor is differentially regulated by progesterone and estradiol in rat uterine epithelial and stromal cells. 811 47

Regression of the CL causes a dramatic decrease in plasma progesterone levels. To test the hypothesis that the decrease in progesterone involves the down-regulation of mRNA encoding the steroidogenic enzymes, cytochrome P450 side-chain cleavage (P450scc) and/or 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), levels of plasma progesterone and luteal mRNA for P450scc and 3 beta-HSD were measured and correlated during induced luteolysis. Holstein heifers (n = 25) were injected with 25 mg prostaglandin F2 alpha (PGF2 alpha) on Day 6 or 7 of the estrous cycle (Day 0 = estrus) to induce luteal regression. To determine acute changes in plasma progesterone during luteolysis, jugular blood samples were obtained from 5 heifers hourly for 12 h, beginning immediately before injection of PGF2 alpha, and assayed for progesterone by RIA. A significant decrease in plasma progesterone levels was observed as early as 1 h after the PGF2 alpha injection (3.62 vs. 2.72 ng/ml, p < 0.05). Progesterone levels continued to decline with time through 12 h after administration of PGF2 alpha. The other 20 animals were ovariectomized at 0 (n = 6), 2 (n = 4), 12 (n = 4), or 24 (n = 6) h after PGF2 alpha. Levels of P450scc and 3 beta-HSD mRNA were determined in extracts of total luteal RNA by ribonuclease (RNase) protection assay. By 2 h after PGF2 alpha, 3 beta-HSD mRNA levels had decreased by about 40% as compared with levels at time 0 (p < 0.05), and a further significant decrease occurred between 2 and 12 h.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Changes in levels of messenger ribonucleic acid for cytochrome P450 side-chain cleavage and 3 beta-hydroxysteroid dehydrogenase during prostaglandin F2 alpha-induced luteolysis in cattle. 814 50

Several studies in the past few years have supported the hypothesis that oxytocin (OT) is synthesized in a paracrine system within the pregnant human uterus and that this paracrine system may be an important regulator of the timing of human parturition. Using ribonuclease protection assays, we have demonstrated a three-fold increase in the rate of synthesis of OT mRNA in human decidua around the time of parturition. We also have shown that a similar increase in OT mRNA and peptide synthesis can be stimulated in vitro by physiological concentrations of estradiol. This increase is inhibited by concomitant use of the estrogen receptor (ER) blocker tamoxifen or by transcription inhibitors. Progesterone had little, if any effect. We also detected mRNAs for ER and progesterone receptor (PR) in amnion, chorion and decidua with the same relative tissue concentrations as OT mRNA. The concentrations of ER but not PR increased significantly around the time of labour onset. To determine if local OT concentrations may be regulated by changes in OT metabolism, we determined kinetic parameters for OT metabolism in decidua, chorion and placenta. [3H]tyrosyl-OT was used as substrate. Metabolites were separated using HPLC and identified using amino acid analysis and mass spectrometry. Metabolism in decidua and chorion occurred predominantly via a cytosolic post-proline endopeptidase and the activity was comparable to placenta. In microsomal fractions, cystine aminopeptidase activity predominated and placenta had significantly more activity than decidua and chorion. There were no changes in any Km or apparent vmax values around the time of parturition. These findings support the existence of a paracrine system within human decidua that involves sex steroids regulating synthesis of OT and that undergoes significant changes around the time of parturition. Changes in local OT concentrations are controlled by rates of synthesis rather than rates of metabolism.
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PMID:Synthesis and metabolism of oxytocin in late gestation in human decidua. 871 92

gamma-Aminobutyric acid (GABA)ergic neurons terminating in the rostral hypothalamus are stimulated by testosterone. To investigate whether this action is mediated locally through androgen receptors in the rostral hypothalamus, bilateral microcannulas (28 gauge) containing the androgen receptor antagonist, hydroxyflutamide (HF), were stereotaxically implanted into the rostral medial preoptic area (rMPA) just dorsal to the major population of GnRH cell bodies. Two days later, blood samples were collected for assay of LH, and animals were killed for determination of GABAergic neuronal activity in tissue dissected from the site of the implanted cannulas. Animals were decapitated either without treatment or 60 min after inhibition of GABA degradation by aminooxyacetic acid (100 mg/kg, ip). The rate of GABA accumulation in the tissue after aminooxyacetic acid treatment was used as a measure of GABA turnover. Levels of messenger RNA for both forms of glutamic acid decarboxylase (GAD65 and GAD67), the rate-limiting enzyme responsible for GABA synthesis also were measured by a microlysate ribonuclease protection assay. LH levels were significantly increased (1.8-fold) in HF-treated animals compared with controls. In the MPA, beneath the implant cannulas, GABA turnover was significantly reduced in HF-treated rats. There was no effect of treatment in the frontal cortex, which was used as a control region. Surprisingly, levels of messenger RNA for both GAD65 and GAD67 were significantly increased in HF-treated rats. The results indicate that GABAergic neurons terminating in the rostral hypothalamus are tonically stimulated by testosterone acting by means of androgen receptors localized in this region. These findings support the working hypothesis that androgen-sensitive GABAergic neurons in the rMPA mediate the negative feedback action of testosterone on GnRH secretion in the male rat.
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PMID:Antiandrogen microimplants into the rostral medial preoptic area decrease gamma-aminobutyric acidergic neuronal activity and increase luteinizing hormone secretion in the intact male rat. 882 73

Down-regulation of the progesterone receptor (PR) by its ligand has been demonstrated in breast cancer cell lines and in the rat uterus. However, in the stromal cells of endometrium, reduction of the PR level is not apparent in the luteal phase of the menstrual cycle. The purpose of this study was to determine the effect of progestin on PR and PR mRNA in isolated human endometrial stromal cells. Western blot analysis showed that progesterone or medroxyprogesterone acetate increased the two isoforms, PR-A and PR-B, in stromal cells but reduced them in glandular epithelial cells. Progestin increased the PR-A and PR-B mRNA by 2- to > 10-fold in the stromal cells of 12 specimens measured by solution hybridization-ribonuclease protection assay. A time study showed that the increase in PR mRNA required at least a 2- to 3-day incubation with progestin and that the high mRNA levels were maintained or increased slightly beyond 10 days of progestin incubation. The stimulatory effect of progestin was inhibited by RU-486 and by cycloheximide, suggesting that the up-regulation requires ligand binding to PR and de novo protein synthesis. Progestin also increased the stability of PR mRNA in endometrial stromal cells. These results demonstrated for the first time that progestin exerts an up-regulation of PR by increasing the steady-state level of PR mRNA specifically in human endometrial stromal cells. The up-regulation of PR by progestin may be mediated in part by progestin-induced endometrial stromal cell factors such as estrogen and insulin-like growth factor-I, both of which stimulated the PR-A and PR-B mRNA in stromal cells.
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PMID:Regulation of progesterone receptor messenger ribonucleic acid by progestin in human endometrial stromal cells. 940 41


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