J Biol Chem. 2002 Apr 12;277(15):13202-9. Epub 2002 Jan 31.
Mutations targeted to a predicted helix in the extreme carboxyl-terminal region of the human estrogen receptor-alpha alter its response to estradiol and 4-hydroxytamoxifen.

Schwartz JA, Zhong L, Deighton-Collins S, Zhao C, Skafar DF.

Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201, USA.

The human estrogen receptor-alpha, a member of the nuclear receptor superfamily, is a ligand-regulated transcriptional modulator. Because comparatively little is known about the extreme carboxyl-terminal region of the estrogen receptor (F domain), we used secondary structure prediction to design mutations that delete the F domain (S554stop), disrupt a possible turn (G556L/G557L), and alter a predicted helix (S559A/E562A, Q565P), and we evaluated the effects of these mutations on hormone binding and transcription activation in response to estradiol and the mixed agonist/antagonist 4-hydroxytamoxifen. Mutations that deleted the F domain (S554stop) or targeted the predicted helix (S559A/E562A, Q565P) greatly reduced or eliminated the agonist activity of 4-hydroxytamoxifen. Deleting the F domain increased the affinity of the receptor for estradiol and decreased the antagonist activity of 4-hydroxytamoxifen. The Q565P mutant exhibited a non-cooperative hormone-binding mechanism, as well as an impaired response to estradiol and increased antagonist activity of 4-hydroxytamoxifen. Our results show that mutations in the F domain alter not only the response to estradiol, the affinity for hormone, and the interaction between receptor subunits but can uncouple the agonist and antagonist activities of 4-hydroxytamoxifen. These results suggest that the F domain modulates the activity of the estrogen receptor-alpha by multiple mechanisms.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11823467&dopt=Abstract estradiol




Stroke. 2002 Feb;33(2):600-5.
17beta-estradiol increases rat cerebrovascular prostacyclin synthesis by elevating cyclooxygenase-1 and prostacyclin synthase.

Ospina JA, Krause DN, Duckles SP.

Department of Pharmacology, College of Medicine, University of California at Irvine, 92697-4625, USA.

BACKGROUND AND PURPOSE: It has been reported that estrogens modulate peripheral vascular synthesis of vasodilatory hormones, including prostacyclin. If this occurs in the cerebral circulation, it could have important consequences in the modulation of cerebral hemodynamic function and improvement of stroke outcome. We investigated the hypothesis that in vivo 17beta-estradiol treatment of ovariectomized rats increases cerebrovascular prostacyclin production via elevation of the enzymes responsible for prostacyclin synthesis. METHODS: Cerebral blood vessels from 17beta-estradiol-treated and nontreated ovariectomized rats were isolated and examined for prostacyclin synthesis by enzyme-linked immunosorbent assay or for protein levels of cyclooxygenase-1, prostacyclin-synthase, and cytosolic phospholipase A2 by immunoblot analysis. RESULTS: We report that chronic in vivo 17beta-estradiol treatment significantly enhanced basal prostacyclin synthesis in rat cerebral blood vessels by 2.6-fold over control. 17beta-estradiol treatment also resulted in a 5.1-fold increase of cyclooxygenase-1 protein and a 6.7-fold increase of prostacyclin-synthase protein in the cerebral vasculature. There was no effect of estrogen on levels of cytosolic phospholipase A2. CONCLUSIONS: Our findings suggest that estrogen influences the biosynthesis of prostacyclin, which may be important in the regulation of cerebral blood flow and thrombosis. This finding may shed light on the mechanisms that govern sex-based differences in cerebrovascular disease.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11823676&dopt=Abstract estradiol




J Cereb Blood Flow Metab. 2002 Feb;22(2):183-95.
17-beta-estradiol induces heat shock proteins in brain arteries and potentiates ischemic heat shock protein induction in glia and neurons.

Lu A, Ran RQ, Clark J, Reilly M, Nee A, Sharp FR.

Department of Neurology and Neurosciences Program, Vontz Center for Molecular Studies, University of Cincinnati, Cincinnati, Ohio 45267, USA.

Estradiol reduces brain injury from many diseases, including stroke and trauma. To investigate the molecular mechanisms of this protection, the effects of 17-beta-estradiol on heat shock protein (HSP) expression were studied in normal male and female rats and in male gerbils after global ischemia. 17-beta-estradiol was given intraperitoneally (46 or 460 ng/kg, or 4.6 microg/kg) and Western blots performed for HSPs. 17-beta-estradiol increased hemeoxygenase-1, HSP25/27, and HSP70 in the brain of male and female rats. Six hours after the administration of 17-beta-estradiol, hemeoxygenase-1 increased 3.9-fold (460 ng/kg) and 5.4-fold (4.6 microg/kg), HSP25/27 increased 2.1-fold (4.6 microg/kg), and Hsp70 increased 2.3-fold (460 ng/kg). Immunocytochemistry showed that hemeoxygenase-1, HSP25/27,and HSP70 induction was localized to cerebral arteries in male rats, possibly in vascular smooth muscle cells. 17-beta-estradiol was injected intraperitoneally 20 minutes before transient occlusion of both carotids in adult gerbils. Six hours after global cerebral ischemia, 17-beta-estradiol (460 ng/kg) increased levels of hemeoxygenase-1 protein 2.4-fold compared with ischemia alone, and HSP25/27 levels increased 1.8-fold compared with ischemia alone. Hemeoxygenase-1 was induced in striatal oligodendrocytes and hippocampal neurons, and HSP25/27 levels increased in striatal astrocytes and hippocampal neurons. Finally, Western blot analysis confirmed that estrogen induced heat shock factor-1, providing a possible mechanism by which estrogen induces HSPs in brain and other tissues. The induction of HSPs may be an important mechanism for estrog




Sheng Li Xue Bao. 2001 Oct;53(5):380-4.
[Down-regulation of ETA receptor of vascular smooth muscle cells by 17 beta-estradiol]

[Article in Chinese]

Wang TH, Tan Z, Liu PQ, Lu W, Yang D, Pan JY.

Department of Physiology, Sun Yat-Sen University of Medical Sciences, Guangzhou 510089. Thwanzsums.edu.cn

In the present study, the effects of 17 beta-estradiol on vascular reactivity of ovariectomized rats and proliferation of cultured rat aortic smooth muscle cells were studied. The vascular reactivity was significantly increased in ovariectomized rats compared with the sham-operated animals. The selective ETA receptor antagonist BQ123 inhibited the increase in [3H]-TdR incorporation in response to ET-1 on vascular smooth muscle cells (VSMCs). 17 beta-estradiol also attenuated the ET-1 effects in a dose-dependent manner. The results of RT-PCR and Western blot show that expression of ETA receptor was decreased after treatment with 17 beta-estradiol. The effect of 17 beta-estradiol was partially inhibited by estrogen receptor antagonist tamoxifen. The above results demonstrate that proliferation of VSMCs stimulated by ET-1 was mainly mediated through ETA receptor. Due to the down-regulation of ETA receptor and mediation of estrogen receptor, 17 beta-estradiol inhibits the ET-1-induced proliferation of VSMCs and decreases the vascular reactivity of ovariectomized rats.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11833423&dopt=Abstract estradiol




Mol Reprod Dev. 2002 Mar;61(3):367-75.
A estradiol-17beta receptor in the reproductive system of the female of Octopus vulgaris: characterization and immunolocalization.

Di Cosmo A, Di Cristo C, Paolucci M.

Faculty of Science, University of Sannio, Via Port'Arsa, Benevento, Italy. dicosmnima.it

In this study, for the first time we have identified an estradiol-17beta receptor (ER) in the reproductive system of the female of Octopus vulgaris. Scatchard analysis revealed that one binding component with high affinity and low capacity for the ligand was present in the cytosol, but not in the nuclear extract of the ovary and the oviduct. A steroid specificity competition assay showed that 3H-estradiol-17beta binding activity showed a preference for estradiol-17beta. DNA-cellulose chromatography confirmed the presence of one 3H-estradiol-17beta binding component. By using antibodies anti ER (578-595), we have localized by Western blotting one band of about 70 kDa. ER immunoreactivity has been localized in the nuclei of the follicle cells of the ovary, in the nuclei of the epithelium lining the proximal portion of the oviduct and in the nuclei, and in the cytoplasm of the inner region of the oviducal gland and in the cytoplasm of the outer region of the oviducal gland. These data, taken together, provide evidence that in Octopus vulgaris the ER has biochemical and immunohistochemical characteristics resembling those of ER in vertebrates. Copyright 2002 Wiley-Liss, Inc.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11835582&dopt=Abstract estradiol




Int J Oncol. 2002 Mar;20(3):589-94.
Low sex steroid environment affects survival and steroid secretion of ovarian tumour cells in primary cultures.

Taube M, Hockenstrom T, Isaksson M, Lindgren PR, Backstrom T.

Department of Clinical Sciences, Obstetrics and Gynaecology, University Hospital of Umea, SE 901 85 Umea, Sweden.

Ovarian epithelial tumours are considered to be endocrine related. The effects of an environment with low levels of the steroid hormones 17 beta-estradiol, testosterone or progesterone on cell survival and steroid secretion were studied in primary cell cultures derived from 25 patients suffering from epithelial ovarian tumours. Tumour cells cultured in 17 beta-estradiol and testosterone showed a reduced cell survival (-10.3 +/- 2.3% and -15.6 +/- 2.7% minimum survival respectively). This reduction was inversely proportional to hormone concentrations within the range studied. No similar effect was observed in the progesterone cultures. It was found that 17 beta-estradiol was secreted from the primary cell cultures and, interestingly, the amount of 17 beta-estradiol secreted increased with increasing levels of 17 beta-estradiol in the environment. Neither progesterone nor testosterone production was observed in any of the cultures studied. It is believed that 17 beta-estradiol has an antiapoptotic effect on ovarian surface epithelial (OSE) cells. Reduction of 17 beta-estradiol in the environment may inhibit this effect, resulting in reduced cell survival. The ability of ovarian epithelial tumour cells to secrete 17 beta-estradiol suggests that epithelial ovarian tumours play an active role in altering their own hormonal environment, promoting tumour progression.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11836573&dopt=Abstract estradiol




Anal Chem. 2002 Feb 1;74(3):533-8.
Electrochemical evaluation of the interaction between endocrine disrupter chemicals and estrogen receptor using 17,beta-estradiol labeled with daunomycin.

Kuramitz H, Natsui J, Sugawara K, Itoh S, Tanaka S.

Division of Material Science, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan.

A new electrochemical screening method for endocrine disrupting chemicals (EDCs) was developed. To evaluate the binding capacity of EDCs to the estrogen receptor (ER), 17beta-estradiol labeled with daunomycin as an electroactive compound was prepared. The electrochemical sensitivity of the prepared labeled estradiol (LE) was high, as compared with daunomycin. The interaction between LE and ER was observed by the decrease in the electrode response of LE, indicating the specific binding of LE with ER. The competitive reaction between LE and 17beta-estradiol for the limiting binding site on ER produced increases in the peak current of LE. The relative standard deviation at 1 x 10(-8) M 17beta-estradiol was about 10.0% (n = 7). The binding affinity between EDC and ER was also evaluated by comparison with 17beta-estradiol-ER interaction. Bisphenol A, p-nonylphenol and p,p'-DDT was used as a test compound. All test compounds demonstrated some ability to bind with ER. This electrochemical binding assay illustrates a new method for evaluating the binding capacity of EDCs to ER without the need for a separation procedure for the bound and free LE.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11838671&dopt=Abstract estradiol




J Appl Physiol. 2002 Mar;92(3):1064-73.
Time- and dose-dependent differential upregulation of three genes by 17 beta-estradiol in endothelial cells.

Villablanca AC, Lewis KA, Rutledge JC.

Division of Cardiovascular Medicine, University of California, Davis, California 95616-8636, USA. avillalanccdavis.edu

The purpose of this study was to identify genetic targets in the vasculature for estrogen by profiling genes expressed in female human aortic endothelial cells exposed to various doses of 17 beta-estradiol at differing concentrations and for differing periods of time. Our approach employed a RT-PCR-based cloning strategy of DNA differential display analysis, with differential expression verified by semiquantitative PCR performed with gene-specific primers. A significant increase in mRNA expression in response to 17 beta-estradiol was observed for the following three genes: aldose reductase (3.4-fold), caspase homologue-alpha protein (4.2-fold), and plasminogen activator inhibitor-1 intron e (2.3-fold). For all three upregulated genes, estradiol-induced upregulation occurred with a similar time course and temporally clustered to the first 24 h after hormone treatment. In addition, the effect of estradiol dose on gene expression was consistent and occurred at physiological concentrations. Our results describe previously uncharacterized estradiol-sensitive time- and dose-dependent regulation of genes with potential importance to vascular function in human endothelial cells.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11842041&dopt=Abstract estradiol




Am J Phys Anthropol. 2002 Mar;117(3):218-27.
Morphological and hormonal parameters in two species of macaques: impact of seasonal breeding.

Muehlenbein MP, Campbell BC, Murchison MA, Phillippi KM.

Department of Anthropology, Yale University, New Haven, Connecticut 06520-8277, USA. michael.net.net

To compare physiological and developmental differences between two cogeneric species that differ by seasonal vs. aseasonal breeding, values for morphological measurements, testicular volume, serum testosterone, estradiol, and dehydroepiandrosterone-sulfate levels were obtained from 53 rhesus during the early breeding season, as well as 41 pig-tailed macaque males maintained at the Tulane Primate Center. The two species exhibited similar body size, testosterone, and estradiol levels, but differed substantially in testicular volume (3.00 +/- 1.7 vs. 1.72 +/- 1.3 cc), abdominal skinfold measures (15.7 +/- 9.2 vs. 9.0 +/- 7.7 mm), and DHEA-S levels (18.0 +/- 11.7 vs. 7.6 +/- 5.4 microg/dl). Significant interaction effects for species by age group were found for weight, tricep circumference, length, and estradiol level. In addition, length was more closely related to testicular volume among rhesus compared to pig-tailed macaques, suggesting different developmental patterns between the species. Predictors of hormonal levels differed between the two species. In the rhesus, estradiol levels were related to testicular volume and testosterone levels while there were no anthropometric predictors of testosterone or DHEA-S. For the pig-tailed macaques, testicular volume was related to tricep circumference, testosterone to triceps skinfold and testicular volume, and estradiol to weight. It is argued that rhesus have larger testes for body size and more abdominal fat deposits during the early breeding season relative to pig-tailed macaques reflecting the increased demands of sperm competition in a seasonally breeding species. Hormonal differences associated with the difference in breeding system appear to be primar