A pharmacophore-based evolutionary approach for screening selective estrogen receptor modulators

We developed a pharmacophore-based evolutionary approach for virtual screening. This tool, termed the Generic Evolutionary Method for molecular DOCKing (GEMDOCK), combines an evolutionary approach with a new pharmacophore-based scoring function. The former integrates discrete and continuous global search strategies with local search strategies to expedite convergence. The latter, integrating an empirical-based energy function and pharmacological preferences (binding-site pharmacological interactions and ligand preferences), simultaneously serves as the scoring function for both molecular docking and postdocking analyses to improve screening accuracy. We apply pharmacological interaction preferences to select the ligands that form pharmacological interactions with target proteins, and use the ligand preferences to eliminate the ligands that violate the electrostatic or hydrophilic constraints. We assessed the accuracy of our approach using human estrogen receptor (ER) and a ligand database from the comparative studies of Bissantz et al. (J Med Chem 2000;43:4759-4767). Using GEMDOCK, the average goodness-of-hit (GH) score was 0.83 and the average false-positive rate was 0.13% for ER antagonists, and the average GH score was 0.48 and the average false-positive rate was 0.75% for ER agonists. The performance of GEMDOCK was superior to competing methods such as GOLD and DOCK. We found that our pharmacophore-based scoring function indeed was able to reduce the number of false positives; moreover, the resulting pharmacological interactions at the binding site, as well as ligand preferences, were important to the screening accuracy of our experiments. These results suggest that GEMDOCK constitutes a robust tool for virtual database screening.     

Estrogen regulation of trefoil factor 1 expression by estrogen receptor alpha and Sp proteins

Estrogen-responsive genes in human breast cancer cells often have an estrogen response element (ERE) positioned next to an Sp1 binding site. In chromatin immunoprecipitation (ChIP) assays, we investigated the binding of estrogen receptor alpha (ER), Sp1, and Sp3 to the episomal and native estrogen-responsive trefoil factor 1 (TFF1; formerly pS2) promoter in MCF-7 breast cancer cells. Mutation of the Sp site upstream of the ERE reduced estrogen responsiveness and prevented binding of Sp1 and Sp3, but not ER to the episomal promoter. In the absence of estradiol (E2), Sp1, Sp3, histone deacetylase 1 (HDAC), and HDAC2, and low levels of acetylated H3 and H4 are associated with the native promoter, with the histones being engaged in dynamic reversible acetylation. Following E2 addition, levels of ER and acetylated H3 and H4 bound to the native promoter increases. There is clearance of Sp1, but not of Sp3, from the promoter while HDAC1 and HDAC2 remain bound. These data are consistent with a model in which Sp1 or Sp3 aid in recruitment of HDACs and histone acetyltransferases (HATs) to mediate dynamic acetylation of histones associated with the TFF1 promoter, which is in a state of readiness to respond to events occurring following the addition of estrogen.     

Suppression of endogenous estrogen during development affects porcine epididymal sperm maturation

Estrogen plays an important role in male reproduction, critical for sustained fertility in some species. Reducing estrogen's interaction with its receptor(s) in monkey and mouse models is associated with reduced sperm motility and, in some cases, documented elimination of sperm fertilizing ability, suggesting that normal epididymal function may be estrogen dependent. The objective of these experiments was to evaluate the effects of reduced endogenous estrogen on development of epididymal function in the pig, a species in which males have very high levels of endogenous estrogen. Letrozole, a potent inhibitor of estrogen synthesis, was administered to neonatal boars from 1 week of age and markedly suppressed estrogen production. Epididymal function assessed as acquisition of sperm fertilizing ability (in vitro fertilization of zona-free oocytes) was reduced in Letrozole-treated animals at 24 and 28 weeks of age (23% and 30% fertilization, respectively compared with 37% and 54% in vehicle controls) but had recovered by 32 weeks of age. Cauda epididymal sperm numbers were reduced in treated animals (35% of control values at 20 weeks of age) but appeared to be recovering at 32 weeks of age. Reduction of endogenous estrogen had no effect on other aspects of epididymal function (percentage of motile sperm, sperm motion parameters, sperm head morphometrics, or ability of sperm to undergo an acrosome reaction). Reducing endogenous estrogen during postnatal development appears to have transient effects on porcine epididymal function. These transient effects suggest that the pig, with its high endogenous estrogen, may respond differently than other species to reduced estrogen synthesis.     

Interstitial Cajal-like cells (ICLC) as steroid hormone sensors in human myometrium: immunocytochemical approach

Expression of estrogen (ER) and progesterone (PR) receptors was investigated in cultured human normal myometrial cells (non-pregnant uterus, fertile period). The ER and PR expression was studied by immunohistochemistry and immunofluorescence on either myocytes or interstitial Cajal-like cells (ICLC). Only those cells double immunostained for c-kit and steroid receptors were considered as ICLC. ER and/or PR immunoreactivity was localized in ICLC, primarily concentrated at the nucleus level, but it was also observed in the cell body (cytoplasm) and processes. Stronger immunopositive reaction in the ICLC nucleus for PR than for ER was noted. Under our experimental conditions, a clear positive repeatable reaction for steroid receptors could not be detected in myocytes. In conclusion, these data suggest that ICLC could be true hormonal 'sensors', possibly participating in the regulation of human myometrial contractions (via gap junctions with myocytes and/or by paracrine signaling).     

雌激素神经保护作用机制:线粒体功能的调节

大量研究表明雌激素具有神经保护作用,但其机制尚不清楚。近年来研究提示,雌激素的神经保护作用与线粒体有着密切联系。线粒体是细胞内能量和活性氧自由基(ROS)的主要来源,对细胞内信号转导、细胞存活与死亡调节等具有十分重要的影响。在生理和病理条件下,雌激素可多方面调节线粒体功能,包括影响ATP与ROS的生成、稳定线粒体膜电位、维护细胞内钙稳态,以及调节线粒体基因和蛋白表达等。本文主要从线粒体角度综述了雌激素神经保护作用及其机制。     

The effects of peptides with estrogen‐like activity on cell proliferation and energy metabolism in human derived vascular smooth muscle cells

Hormone replacement therapy (HRT) for post‐menopausal symptoms in diabetes is associated with increased risk of coronary heart disease and stroke. Therefore, there is a need for new HRT with no adverse effects on diabetic post‐menopausal women. We developed peptides as potential estrogen mimetic compounds and now we evaluated the effects of the most efficacious peptide; hexapeptide estrogen‐mimetic peptide 1 (EMP‐1) (VSWFFE) in comparison to estrogen (E₂) and peptides with weak activity A44 (KAWFFE) and A45 (KRAFFE) on modulation of cell proliferation of vascular smooth muscle cells (VSMC) growing in normal (ng) or high glucose (hg) concentrations. In ng EMP‐1‐like E₂ inhibited cell proliferation at high concentration, and stimulated at low concentration. EMP‐1 did not affect E₂ stimulation of DNA, but inhibited E₂ inhibition of cell proliferation at high concentration. All effects by the combination of EMP‐1 and E₂ were abolished at hg. A44‐stimulated cell proliferation at all concentrations and A45 had no effect. When A44 was co‐incubated with E₂ at both concentrations, DNA synthesis was stimulated, but abolished at hg. A45 abolished E₂ stimulation and inhibition of cell proliferation at both glucose concentrations. All peptides tested except A45‐stimulated CK‐specific activity at both glucose concentrations. In hg A44 stimulation of DNA was unaffected as well as its inhibition by EMP‐1. EMP‐1 and A44 similar to E₂‐stimulated MAPK activity in ng or hg, suggesting similar mechanism of action. The results presented here suggest that EMP‐1 provided it acts similarly in vivo can replace E₂ for treatment of post‐menopausal women in hyperglycemia due to diabetes. J. Cell. Biochem. 110: 1142–1146, 2010. Published 2010 Wiley‐Liss, Inc.     

雌激素受体与神经系统疾病

雌激素受体是类固醇激素受体超家族成员之一,是一种配体依赖性转录因子,具有广泛的生物学功能。雌激素受体在脑内具有广泛的分布,且与一些神经系统疾病的发生发展相关。就雌激素受体在脑内的分布及其与神经系统疾病的关系进行论述。