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

---

Query: EC:3.1.21.1 (DNase)
7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sixty-two primary breast carcinomas were analyzed for estrogen receptor (ER) by both the dextran-coated charcoal (DCC) technique and estrogen receptor immunocytochemical assay (ER-ICA) on cryostat and permanent sections. Paraffin sections of formalin-fixed breast tissue underwent DNase pretreatment to expose the nuclear antigenic site as described by P. Shintaku and J. H. Said (Am J Clin Pathol 87:161, 1987). The results of immunocytochemical staining agreed with those of the DCC biochemical assay in 89% of paraffin-sectioned tissue and in 94% of the cryostat sections. Comparison of the results of ER-ICA on permanent and frozen sections showed 85% agreement (kappa statistic = 0.704). This study suggests that ER can be demonstrated immunocytochemically on paraffin-sectioned breast tissue. However, although highly specific, immunoperoxidase determination on paraffin-embedded tissue is less sensitive than that on frozen tissue. The commercial source of DNase, length of incubation, and tissue fixation are important factors in the demonstration of ER immunoreactivity. The assay may offer an alternative for assessment of ER when tissue is not suitable or available for biochemical assay or conventional cytochemical analysis.
...
PMID:Potential value of estrogen receptor immunocytochemical assay in formalin-fixed breast tumors. 170 13

We have identified an estrogen-responsive enhancer element (DH3 ERE) in the estrogen-induced DNAase I-hypersensitive region III of the chicken ovalbumin gene, which is located approximately 3.3 kb upstream from the mRNA start site and does not contain palindromic ERE. Four TGACC half-palindromic motifs, separated from each other by more than 100 bp, are responsible for conferring estrogen inducibility either to the proximal ovalbumin gene promoter or to heterologous promoters. Thus, widely spaced half-palindromic ERE motifs can act synergistically. Each half-palindromic motif was shown to bind the estrogen receptor (ER) with a low efficiency in vitro. However, two widely spaced half-palindromic motifs bound the ER cooperatively, much more efficiently than expected from binding to isolated half-ERE motifs. The ovalbumin promoter half-palindromic ERE motif located close to the TATA box was required for the activity of the distal DH3 ERE, but could be replaced by the binding sites of other transactivators.
...
PMID:A far upstream estrogen response element of the ovalbumin gene contains several half-palindromic 5'-TGACC-3' motifs acting synergistically. 173 78

Expression of the vitellogenin genes in avian and amphibian liver is regulated by estrogens. The DNA elements mediating estrogen induction of the various vitellogenin genes of chicken and Xenopus encompass one or more copies of a 13-mer palindromic sequence called the estrogen-responsive element (ERE). Here we show that upon incubation with the purified estrogen receptor (ER) from calf uterus the Xenopus vitellogenin A2 gene yields a DNase-I footprint over the ERE between -331 and -319. This element does not mediate the response to glucocorticoids or progestins in T47D cells. The three guanine residues in each half of the palindrome are protected against methylation by dimethylsulfate after incubation with ER, but not with glucocorticoid (GR) or progesterone (PR) receptors. In contrast, the chicken vitellogenin II gene exhibits multihormonal regulation by estrogens, progestins, and glucocorticoids in T47D and MCF7 cells. Regulation is mediated by the DNA region between -721 and -591 that contains four binding sites for hormone receptors, as demonstrated by DNase-I footprints and methylation protection experiments. The two distal and most proximal binding sites are recognized by ER, GR, and PR, whereas the central binding site is only bound by ER and GR. At suboptimal concentrations, estrogens and progestins or glucocorticoids act synergistically. In experiments using a DNA fragment containing an ERE adjacent to a glucocorticoid-responsive element/progesterone-responsive element, ER and PR bind synergistically to their corresponding sites, perhaps explaining the functional synergism of both hormones. Thus, two very different regulatory elements are used to mediate estrogen induction of related genes in chickens and amphibians.
...
PMID:Hormonal regulation of vitellogenin genes: an estrogen-responsive element in the Xenopus A2 gene and a multihormonal regulatory region in the chicken II gene. 189 Sep 89

In vitro studies have demonstrated that the estrogen receptor (ER) can bind to the rat PRL estrogen response element (ERE) located 1700 basepairs upstream of the transcriptional start site. However, the mechanism by which the receptor-DNA complex influences the activity of RNA polymerase located in the promoter region is not understood. To begin investigating this process, we developed cell lines derived from GH3 cells that contain steroid-responsive bovine papillomavirus minichromosomes. Within these minichromosomes is a hybrid gene composed of the 5' flanking region of the PRL gene, driving the expression of the Tn5 gene. The episomal PRL DNA sequences responded to 17 beta-estradiol (E2) by increasing the rate of Tn5 gene transcription. Nucleosome mapping experiments using micrococcal nuclease demonstrated that nucleosome-like structures were assembled on the minichromosome in an ordered array separated by 150-200 basepairs of DNA. Novel S1 nuclease as well as DNase-I-hypersensitive sites in the chromatin of the promoter and distal regulatory regions of the episomal PRL gene were detected by indirect end-labeling studies. The nuclease hypersensitive sites in the distal region containing the ERE were modified after treatment of the cells with either E2 or the antiestrogen 4-hydroxytamoxifen. However, only E2 treatment of cells resulted in an increase in the nuclease hypersensitivity of the promoter region and induced gene expression, while antiestrogen treatment had no effect on either parameter. This suggests that complex interactions between factors located at the distal and proximal regulatory regions ultimately determine the transcriptional response of the PRL gene to E2.
...
PMID:An interaction between the 5' flanking distal and proximal regulatory domains of the rat prolactin gene is required for transcriptional activation by estrogens. 196 74

The transcription of the progesterone receptor gene is induced by estrogens and decreased by progestins. Studies were performed to define the regions of the gene and the molecular mechanisms involved. No hormonal regulation could be observed using 5' flanking regions of the gene up to -2762 in front of a heterologous gene. Estrogen and progestin regulation could be observed only when using fragments of the gene extending down to +788. Progressive deletions from the 5' and 3' ends, site-directed mutagenesis and DNase protection experiments with purified estrogen receptor suggested that the biologically active estrogen responsive element (ERE) is present at +698/+723, overlapping the initiation of translation. An oligonucleotide was synthesized bearing this ERE and shown to impart estrogen inducibility to a heterologous gene. Its regulation by anti-estrogens corresponded to that of the in situ progesterone receptor gene since tamoxifen was a partial agonist whereas ICI 164384 was a full antagonist. This ERE also mediated down-regulation by progestins in the presence of the progesterone receptor, even though it has no progesterone receptor binding ability. DNase footprinting showed that this effect was not due to a decrease of estrogen receptor affinity for the ERE in the presence of progesterone receptor. Finally, use of deletion mutants of the progesterone receptor showed that the steroid binding and the DNA binding domains were necessary for down-regulation whereas deletions of various parts of the N-terminal domain were without effect.
...
PMID:Characterization of the hormone responsive element involved in the regulation of the progesterone receptor gene. 205 Jan 23

We have studied by immunocytochemistry and monoclonal antibodies the presence and localization of estrogen receptors, progesterone receptors, and a 24-kD estrogen-regulated heat shock protein in biopsies from breast and endometrial cancer patients. Three different tissue processing protocols were used to colocalize the antigens in the same tissue sections: a) frozen sections, b) formalin fixation with routine paraffin embedding, and c) picric acid-formaldehyde (PAF) fixation with a rapid embedding in paraffin. Frozen sections showed good receptor staining but poor 24-kD protein immunoreactivity, while routine paraffin sections (with or without DNase pretreatment) were inadequate to reveal the nuclear receptor proteins at the same level seen in frozen sections. On the other hand, all three proteins could be detected satisfactorily in PAF-fixed paraffin-embedded tissue. Using this procedure we were able to visualize 24-kD protein and estrogen receptor or progesterone receptor in individual cells in paraffin sections. The study revealed that in all of the estrogen receptor positive breast and endometrial tumor samples, almost 90% of the cells expressing the cytoplasmic 24-kD protein contained estrogen receptor in the cell nucleus. In contrast, 24-kD immunoreactive cells did not express progesterone receptors in almost 40% of the progesterone receptor positive tumor samples.
...
PMID:Colocalization of estrogen and progesterone receptors with an estrogen-regulated heat shock protein in paraffin sections of human breast and endometrial cancer tissue. 208 75

The interaction of partially purified calf uterine estradiol-charged estrogen receptor ([3H]ER) with rat nuclei was studied in vitro. We previously observed a significantly greater number of [3H]ER binding sites (at saturation) in nuclei of R3230AC mammary tumors from intact vs ovariectomized (ovex) rats with no difference in the affinity of [3H]ER binding for these nuclei. We now report on the nuclease sensitivity of [3H]ER binding sites in nuclei from these tumors and from normal rat tissues. Digestion of tumor nuclei with deoxyribonuclease I (DNase I) prior to incubation with [3H]ER in vitro resulted in a progressive loss of [3H]ER binding capacity, which was not accompanied by alterations in the affinity of [3H]ER for the nuclei (Kd = 1-3 nM). A significantly lower concentration (P less than 0.005) of DNase I eliminated 50% of the [3H]ER binding sites in nuclei of tumors from intact hosts (8 unit.min/ml) compared to tumors from ovex hosts (22 unit.min/ml). These results indicate that DNA regions capable of binding ER are more susceptible to DNase I digestion in tumors from intact rats than those from ovex hosts, suggesting that the endogenous hormonal milieu is responsible, at least in part, for maintenance of nuclease-sensitive DNA conformations in this hormone-responsive mammary tumor. The amount of DNase I required to eliminate 50% of [3H]ER binding to nuclei from lactating mammary gland, liver, and kidney ranged from 14 to 56 unit.min/ml. Therefore, accessibility of [3H]ER binding sites to nuclease digestion in normal rat tissue is generally less than that of R3230AC tumors.
...
PMID:Nuclease sensitivity of estradiol-charged estrogen receptor binding sites in nuclei isolated from normal and neoplastic rat mammary tissues. 219 77

Uteroglobin is expressed in various tissues of the rabbit under complex hormonal control. In the endometrium the uteroglobin gene is transcribed only in epithelial cells after administration of ovarian hormones. In this paper we demonstrate that within the promoter region of the rabbit uteroglobin gene, there is a functional estrogen-responsive element (ERE) located between -265 and -252. Hybrid constructions containing sequences of the uteroglobin promoter up to -299, linked to the chloramphenicol acetyltransferase gene of E. coli respond to estrogens in gene transfer experiments, whereas a deletion that removes half of the ERE does not. A synthetic oligonucleotide corresponding to the putative ERE is able to confer estrogen inducibility to an otherwise unresponsive promoter. Binding experiments with purified estrogen receptor from calf uterus reveal a DNase-I footprint over the ERE. Within this protected region six guanine residues that have been shown to be contacted by the receptor in other EREs are protected against methylation by dimethylsulfate in the presence of the estrogen receptor. We compare this ERE with the vitellogenin A2 ERE from Xenopus and find that the relative affinity of the uteroglobin ERE is slightly lower than that of the vitellogenin ERE. Thus, this uteroglobin ERE could be involved in physiological regulation of uteroglobin expression in the genital tract.
...
PMID:The uteroglobin promoter contains a noncanonical estrogen responsive element. 228 Jul 77

Antagonism to estradiol has been examined in murine uteri. When tamoxifen was administered simultaneously with estradiol (0.05 microgram/mouse), it was able to act as an antagonist over the dosage range 0.05-50 micrograms/mouse. The metabolite 4-hydroxytamoxifen (4OH-tamoxifen) had high affinity for estrogen receptors and was a slightly better antagonist over the dosage range 0.005-1 microgram/mouse. After uteri were exposed to either [3H] estradiol or [3H]4OH-tamoxifen, receptors complexed with [3H] estradiol penetrated a chromatin region, which was released as the Mg2+-soluble chromatin fraction after DNAase I treatment more readily than receptors complexed with [3H]4OH-tamoxifen. [3H]4OH-tamoxifen-receptor complexes could not be driven into the Mg2+-soluble chromatin fraction by increasing the ligand concentration during translocation. Relative to [3H]estradiol, significantly more [3H]4OH-tamoxifen was observed to associate with uterine cells and to penetrate the nucleus so that neither restricted entry nor extranuclear partitioning could explain the failure of [3H]4OH-tamoxifen-receptor complexes to enter the Mg2+-soluble chromatin. Bleomycin, an agent that interrupts DNA continuity, did not interfere with the appearance of estrogen receptor activity in the Mg2+-soluble chromatin fraction. Preincubation of intact uteri in the presence of molybdate (20 mM) did inhibit the appearance of receptor activity in this chromatin fraction; however, this effect did not occur through inhibition of receptor activation, but, rather, through the lowering of receptor activity in all chromatin fractions. In the studies reported here, the chromatin positioning of estrogen receptors complexed with estradiol appeared to be distinct from the positioning of receptors complexed with 4OH-tamoxifen. These observations suggest an additional basis from which the mechanisms separating the actions of estrogen agonists and antagonists can be approached.
...
PMID:Antagonism to estradiol in the mouse: reduced entry of receptors complexed with 4-hydroxytamoxifen into a Mg2+-soluble chromatin fraction. 242 13

Immunohistochemical and immunochemical analysis using Western blot techniques were carried out with estrogen receptor (ER) monoclonal antibody H-222 to 1) clarify the "nuclear translocation" phenomenon of ER, 2) elucidate the primary nuclear binding site of ER, and 3) to evaluate the binding force between ER and its nuclear binding site in the uterus of ovariectomized adult mice. Exclusive nuclear localization of ER was recognized in the epithelial cells, stroma cells, and smooth muscle cells. Uterine tissues prepared from animals injected with saline, 17 beta-estradiol (E2), estriol (E3), and diethylstilbestrol (DES) exhibited almost the same ER immunostaining when they were fixed prior to sectioning (prefixation method) and frozen sections were used. On the other hand, when fresh-frozen sections were fixed before or after incubation with various solutions (postfixation method) and then treated with various salt solutions, greater differences were seen in immunostaining of ER between saline-injected and hormone-treated animals. Immunostaining of ER in control animals was low after incubation with PBS (0.01 M phosphate buffer containing 0.16 M NaCl, pH 7.2), whereas uterine tissue from hormone-injected mice showed strong nuclear immunostaining after this treatment. After treatment with 0.4 M KCl or 0.5 M NaCl, immunostaining in the uterus of both hormone-injected and control animals was completely abolished. DNase treatment caused an almost complete loss of immunostaining of ER; however, RNase digestion slightly increased immunoreactivity in both E2-injected and control animals. Quantitative analysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot techniques showed that after incubation of tissue sections for 30 min with PBS, 0.4 M KCl, or DNase, 60%, 10%, and 30% of ER were present, respectively, compared to amount of ER present in unincubated sections. These findings suggest the following for the ER in uterine tissue; nuclear occupancy is a phenomenon that occurs due to a differential affinity between occupied and unoccupied receptors in the nucleus; after hormone treatment, the receptor levels do not fluctuate in the nucleus to the extent demonstrated by binding assays; and the properties of the ER detected in the immunohistochemical analysis are identical to those observed in biochemical studies.
...
PMID:Immunological analysis of the biochemical properties of the uterine estrogen receptor. 277 19


1 2 3 4 Next >>

---