Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00691 (EE2)
 7,802 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Norethindrone (ENT), which is a representative in estrane series of progestogen, is not only strongly progestational but also estrogenic and in some cases, antiestrogenic. To understand progestational effect and antiestrogenic effect, the interactions of ENT on estrogen and progestogen receptors were studied in the uterine cytosol of white female rabbit. The 274,200 X G supernatant of uterine homogenate was used as cytosol. 3H-Estradiol, 3H-Progesterone, 3H-ENT or cold ENT were incubated with uterine cytosol at 4 degrees C for 2 hours. Results are as follows: 1. Sucrose gradient centrifugation [5 approximately 20% linear and 40,000 rpm (159,200 X G) for 16 hours at 4 degrees C]: ENT was bound to extrogen 8S receptor in immature rabbit uterus (Fig. 2 & 3), and to progestogen 8S receptor in estrogen primed rabbit uterus (Fig. 5). 2. Kinetic study, determined by dextran coated charcoal (0.001% dextran and 0.1% charcoal): (1) In the uterine cytosol of immature rabbit, 3H-estradiol-receptor binding was observed with Kd divide by 3.6 X 10-9 M and it was revealed that ENT was a competitive inhibitor to this binding with Ki divide by 2.6 X 10-6 M, as in Fig. 6. (2) 8S component, obtained by centrifugation of uterine cytosol (Fig. 1) in estrogen primed rabbit, binds 3H-progesterone with Kd divide by 8.1 X 10-10 M and Bm (maximal binding sites) divide by 5.0 X 10-8 M/mg of protein, and ENT was a competitive inhibitor in this binding with Ki divide by 2.3 X 10-9 M (FIG. 7 & 8). 3H-ENT-8S binding was demonstrated with Kd divide by 1.1 X 10-9 M and Bm divide by 8.7 X 10-8 M/mg of cytosol protein (Fig. 8). These results indicate: (a) ENT is bound to both estrogen and progestogen receptors in 8S macromolecules of uterine cytosol, (b) competitive inhibition of ENT to these bindings indicated that ENT is bound to these receptors at the steroid binding sites where estradiol and progesterone bind to, (c) ENT has much more affinity to progestogen receptor (Ki divide by 2.3 X 10-9 M) than to estrogen receptor (Ki divide 2.6 X 10-6 M), (d) while ENT is bound to progestogen and estrogen receptors at the same time, Bm of ENT (8.7 X 10-8 M/mg of cytosol protein) is more than Bm of progesterone (5.0 X 10-9 M/mg of cytosol protein), and Kd of ENT (1.1 X 10-9 M) was less than Ki of ENT (2.3 X 10-9 M) in the binding to progesterone-receptor. Biologically, while ENT is bound to progestogen -receptor with high affinity and to estrogen receptor with low affinity, ENT is actually progestational in low dose and antiestrogenic in high dose but the anti-estrogenicity seems to be incomplete in vivo as ENT may be metabolized to a potent estrogenic compound, ethinyl estradiol
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PMID:[Interaction of norethindrone on estrogen and progesterone receptors in the rabbit uterine cytosol (author's transl)]. 18 90

The uterotropic and antiuterotrapic effects of a variety of structural derivatives of the nonsteroidal antiestrogen tamoxifen have been determined in the rat and the mouse. One derivative, monohydroxytamoxifen, was found to be a potent antiestrogen in the rat, with a high affinity for the estrogen receptor. Various techniques of sucrose density gradient analysis were used to demonstrate that estradiol and tamoxifen bind to the rat uterine cytoplasmic estrogen receptor. Estrogens and antiestrogens provoke the translocation of estrogen receptors to the nucleus and deplete the cytoplasmic estrogen receptor pool for short or long periods depending on the dose administered. Estradiol stimulates endometrial hyperplasia with an increase in total uterine DNA content, whereas tamoxifen stimulates endometrial hypertrophy with only a slight increase in uterine DNA content. It is concluded that the molecular shape of the ligand that binds to the estrogen receptor determines antiestrogenic activity.
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PMID:Nonsteroidal antiestrogens: their biological effects and potential mechanisms of action. 20 80

A nuclear subfraction containing bound estrogen receptor in presumed complex with its nuclear acceptor site has been partially purified from hen oviduct. Sucrose density gradient ultracentrifugation was used to separate mechanically sheared chromatin (i.e. lysed nuclei) into several fractions which differed in protein to DNA ratio as well as in vitro template activity. Gradient fractions were then examined for the presence of bound estrogen receptors. Care was taken to use physiological ionic strength buffers when preparing nuclei since the number of estrogen receptors per nucleus decreased from 5600 to 1600 when nuclei prepared in low ionic strength (mu = 0.013 M) were compared with nuclei prepared in physiological ionic strength (mu = 0.2 M). [3H]Estradiol was introduced into nuclear estrogen receptors by exposing minced oviduct to labeled hormone in tissue culture or by exchanging nuclear estrogen receptor complexes formed in vivo with labeled hormone. In all cases, receptor was found in a fast sedimenting nuclear subfraction of low in vitro template activity. Sodium dodecyl sulfate-gel electrophoresis revealed no differences between proteins from receptor-containing and slower sedimenting fractions. Hybrdization experiments using a cDNA probe made from ovalbumin mRNA indicated no enrichment of this gene in DNA from receptor-containing nuclear material. Salt-extracted nuclear estrogen receptor was shown to partially aggregate to fast sedimenting species of heterogeneous size when sedimented in gradients containing low salt concentrations. Bound receptors were distinguished from such receptor aggregates using a novel electrophoresis technique. In addition, receptor aggregates could be disrupted in high salt, while bound receptors were resistant to this treatment. The number of exchangeable nuclear estrogen receptors in immature chicks given secondary estrogen stimulation was compared with birds that had been withdrawn from hormone. The number of receptors per nucleus was shown to be higher in animals given secondary stimulation, and these receptors were associated exclusively with fast sedimenting nuclear material.
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PMID:Isolation of estrogen receptor in complex with a discrete nuclear subfraction from hen oviduct. 42 74

The estrogen receptor has been purified to homogeneity from calf uterus cytosol by sequential affinity chromatography by using heparin--Sepharose 4B and 17-hemisuccinyl-17beta-estradiol-ovalbumin--Sepharose 4B. The procedure yields about 1.2 mg of receptor protein from 1 kg of calf uteri, with a recovery of 53%. The receptor protein, as a complex with 17beta-[3H]estradiol, is purified more than 99%. A single band is seen on polyacrylamide gel ectrophoresis under nondenaturing conditions. 17beta-[3H]Estradiol comigrates with the protein band. As computed from the specific activity of radioactive hormone, 64,450 g of purified receptor protein binds 1 mol of 17beta-estradiol. 17beta-[3H]Estradiol bound to the protein is displaced by estrogenic steriods but not by progesterone, testosterone, or cortisone. As judged by chromatography on calibrated Sephadex G-200 columns, the purified receptor is identical with native receptor in crude cytosol: both show a Stokes radius of 6.4 nm. On sucrose gradient in low-salt buffer, the purified receptor sediments at 8 S. On electrophoresis in NaDodSO4 gels, the purified receptor migrates as a single protein band with an apparent molecular weight of 70,000. The sedimentation coefficient measured on sucrose gradients in the presence of chaotropic salts [1 M NaBr or NaSCN (0.1 M)] is 4.2 S. We conclude that the estrogen receptor of cytosol consists of a single subunit weighing about 70,000 daltons and endowed with one estrogen binding site. Under native conditions in cytosol, several subunits associate to form a quaternary structure with a Stokes radius of 6.4 nm.
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PMID:Estrogen-binding proteins of calf uterus. Purification to homogeneity of receptor from cytosol by affinity chromatography. 44 62

The dissociation of estradiol from the estrogen receptor occurs in two kinetic phases: a fast component having a half-time of approximately 3 min and a slower, or second, dissociating component having a half-time of approximately 95 min at 28 degrees. The fast component is produced by the dissociation of estradiol from the nonactivated 4 S receptor, a monomer. Thus, the magnitude of the fast component of the [3H] estradiol biphasic dissociation curve is proportional to the fraction of the receptor in the nonactivated state. The slow component is the estradiol dissociating from the activated 5 S receptor, a dimer. The salt-extracted estrogen receptor isolated from uterine nuclei shows a single, slow dissociating component equal to the slower component of the cytoplasmic biphasic dissociation curve. Estradiol binding shifts the receptor equilibrium from the low affinity nonactivated 4 S receptor toward the high affinity activated 5 S receptor. The kinetics of estriol dissociation from the receptor shows a larger fractional magnitude for the fast component and a faster second dissociating component than estradiol. This suggests that estriol transforms a smaller fraction of the receptor to the activated state and that the activated estriol receptor has a shorter half-time than estradiol. The biphasic dissociation kinetics of an estrogen from the receptor provides a new and sensitive criterion for measuring receptor activation.
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PMID:The role of ligand-binding as a determinant of the structure and activation of the estrogen receptor. 47 83

The involvement of rotenone in rat mammary carcinogenesis has been suggested to occur through estrogenic effects. This hypothesis was tested by determining the extent of rotenone inhibition of 17 beta-estradiol binding to the estrogen receptor and of the 17 beta-estradiol-induced uterotrophic response in ovariectomized Sprague-Dawley rats. Estradiol binding to the uterine estrogen receptor in the presence of rotenone was determined by charcoal assay and Scatchard analysis. Additionally, 17 beta-estradiol-receptor interactions were assessed on sucrose density gradients. No inhibition of binding was observed in either assay with ratios of rotenone/17 beta-estradiol in excess of 10,000. Finally, an in vivo approach was used to extend the in vitro data. Silastic capsules containing rotenone or 17 beta-estradiol were implanted in various combinations into eight groups of ovariectomized Sprague-Dawley rats (four rats/group). After five days, uteri were removed and weighed. An analysis of variance revealed that rotenone neither interfered with 17 beta-estradiol-induced uterine weight gain nor displayed any uterotrophic properties by itself. Results from these three procedures demonstrate that rotenone does not act as an estrogen or as an estrogen antagonist. Additionally, there were no other effects attributable to rotenone.
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PMID:Failure of rotenone to interfere with 17 beta-estradiol action in the rat uterus. 49 75

The antiestrogen tamoxifen has been used successfully in the treatment of breast cancer. In an attempt to elucidate its mode of action, its effects on steroid hormone receptor concentration and RNA polymerase activities in the uteri of ovariectomized rats have been compared with those of estradiol. A single dose of estradiol and tamoxifen, separately or in combination, produced slight increases in uterine wet weight 12 h after injection. Whereas both estradiol and tamoxifen could promote translocation of the estrogen receptor, only estradiol caused cytoplasmic replenishment of the receptor. Both compounds, separately and in combination, stimulated the production of cytoplasmic progesterone receptor 12 h after treatment. Estradiol produced and maintained significant elevations in RNA polymerase I activity, whereas the effects on this enzyme brought about by taxoxifen were less and transitory. However, estrogen and antiestrogen caused equal increases in RNA polymerase II activity, but, again, the effects of taxoxifen were shortlived when compared to those brought about by estradiol. Stimulation of RNA polymerase II activity was due to the availability of increased numbers of apparent initiation sites. These results point to a basic inefficacy in the antiestrogen-receptor complex; although it is able to promote early tissue responses characteristic of an estrogen, these cannot be sufficiently maintained.
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PMID:Effects of estradiol and the antiestrogen tamoxifen on steroid hormone receptor concentration and nuclear ribonucleic acid polymerase activities in rat uteri. 49 77

The synthesis of biospecific adsorbents for the purification of the cytosol estrogen receptor from calf uterus is described. The characteristic of several estradiol derivatives, spacer chains, and insoluble matrix were systematically studied. Estradiol derivatives substituted at positions C2, 3, 4 7 alpha, 17 alpha, and 17 beta were tested for their affinities for the receptor; positions 7 alpha and 17 alpha were the most suibable. Acidic compounds had lower affinities than their methylester analogues. Long chain derivatives bound the receptor less firmly than corresponding shorter chains. However, when these ligands were attached to an insoluble matrix, the long spacer chain derivatives (greater than or equal to 14 atoms) were more efficient than the shorter ones. There was a satisfactory parallelism between affinities of free ligands and receptor binding to the respective biospecific adsorbents. On the basis of their stability in the presence of cytosol (no release of ligand), due to the absence of ester bonds, long chains were selected as spacers. Both acrylamide and agarose biospecific adsorbents displayed some ionic exchange capacity and consequently nonspecifically bound proteins; the influence of this nonspecific binding on the purification of the receptor was studied. On the basis of their stability, of their binding specificity, and of their selectivity for the receptor, the estradiol-7 alpha derivative adsorbents were selected for the purification of the receptor.
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PMID:New biospecific adsorbents for the purification of estradiol receptor. 55 54

Following in vivo ethinyl estradiol (EE2) administration (100 microgram sc) to adult female rats, the estradiol-specific binding sites (ESBS) of liver cytosol were markedly reduced at 30 and 60 min. The reduction at 30 min was to one-quarter of that found in rats treated with vehicle alone. Coincident with this reduction, nuclear ESBS were increased. The ESBS of partially purified cytosol and of dense sucrose-purified nuclei were determined by gel filtration after incubations with tritiated estradiol using exchange assay conditions. An elevated temperature during the exchange assay incubations was necessary to demonstrate most of the ESBS in purified nuclei of EE2-treated rats and suggested that estrogens are attached at these sites. Following administration of 5 microgram EE2, the decrease in cytosol ESBS and the increase in nuclear ESBS were smaller. In contrast, 5 microgram EE2 was as effective as 100 microgram EE2 in substantially increasing the ESBS observed in uterine nuclear fractions. The low level of ESBS found in whole brain purified nuclei was unchanged by 100 microgram EE2 administration. The steroid specificity and proteolytic enzyme sensitivity of the purified nuclear ESBS of treated rats were similar to that of the partially purified cytosol ESBS of rats treated with vehicle alone. The data are consistent with the ESBS being estrogen receptor proteins which translocate from the liver cytosol to the nucleus after estrogen administration in vivo.
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PMID:Estrogen receptor in rat liver: translocation to the nucleus in vivo. 74 66

Estradiol, estradiol-16alpha, estriol and a series of positional isomers of estriol were tested for their post-coital contraceptive activity, and their ability to compete with estradiol for the cytosolic estrogen receptor protein of rat uteri. Estrogenicity was determined for each compound in immature rats with single injections and in mature castrated rats by injecting the lowest fully contraceptive dose for four consecutive days. All compounds were active anti-implantational agents, varying in required dosage from 4 mug to 2000 mug (total dosage over 4 days). The rank order or contraceptive activity was found to be: estradiol greater than estriol = epiestriol greater than 11beta - (OH) - estradiol greater than estradiol - 16alpha greater than 7alpha-(OH)-estradiol greater than 6beta-(OH)-estradiol, while the order of estrogenicity at levels of contraceptive activity in the ovariectomized mature rat was: epiestriol = estriol less than 7 alpha - (OH) - estradiol less than estradiol - 16alpha less than 6beta - (OH) - estradiol = 11beta - (OH)- estradiol less than estradiol-17beta. Reasonably good correlation between competition for estrogen receptor and anti-implantational activity was observed. The most active binding competitors were estradiol-16alpha, epiestriol, and estriol which showed an affinity from 50-20% that of estradiol, while the other compounds had 3% or less binding competition for estradiol.
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PMID:Post-coital contraceptive activity and estrogen receptor binding affinity of phenolic steroids. 83 36


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