• Asian-Australasian Journal of Animal Sciences
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• 제16권12호
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• pp.1716-1721
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• 2003

Steroid hormones and their receptors play an important role in reproductive process. Estrogen is intimately involved with pregnancy and its function is mediated through the estrogen receptor which has been chosen as a candidate gene to study litter size in pigs. In this study, we report that two estrogen receptor variants, designated pER-1 and pER-2 were co-expressed in the uteri of normal cycling Lan-Yu pig (Sus vittatus; a small-ear miniature in Taiwan) with the pER-1 expression level appeared to be several times higher than that of pER-2. These receptor variants were isolated using reverse transcription-PCR from the pig uteri and their sequences were determined. The pER-1 and pER-2 sequences, which are homologous to those found in other mammalian estrogen receptors, encode putative proteins consisting of 574 and 486 amino acids, respectively. A deletion in exon I was identified in both sequences, with deletion lengths of 63 bp in pER-1 and 327 bp in pER-2. The deletion in pER-1 is internal to that in pER-2 and both deletions resulted in a truncation of the B domain, which confers the transactivating activity of estrogen receptor protein. This result describes the existence of estrogen receptor variants with a deletion in exon I and implies the possibility that physiological functioning of an estrogen receptor may not require the presence of an intact B domain.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2003년도 Annual Meeting of KSAP : International Symposium on Pharmaceutical and Biomedical Sciences on Obesity
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• pp.70-70
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• 2003

Estrogen receptor is a ligand-activated transcription factor. Its action depends on the receptor, its ligand, and its coactivator proteins. As a consequence, the concentration of the receptor is a major component that governs the magnitude of the estrogen response. Despite the extensive knowledge on mechanism of estrogen receptor action, regulation of estrogen receptor itself is not very well understood. Estrogen receptor is known to be downregulated under hypoxia leading to inhibition of estrogen receptor mediated transcription activation. We have studied mechanism of loss of estrogen responsiveness under hypoxia. We found that Hif-l${\alpha}$, a major transcription factor regulating hypoxic response, inhibited transcription of estrogen response element driven luciferase gene by expression of HIF-l${\alpha}$/vp16 construct designed to contain transcription activity under normoxia. This loss of estrogen responsiveness appears to be the result of ER${\alpha}$ downregulation. ER${\alpha}$was downregulated at the levels of ligand-biding and protein within l2-24h, and the response was blocked by the proteasome inhibitor MG132, protein synthesis inhibitor cyclohexamide, and tyrosine kinase inhibitor Genistein. These results demonstrate that Hif-l${\alpha}$ downregulates ER${\alpha}$ by proteasome dependent pathway.

• 생명과학회지
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• 제13권3호
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• pp.314-323
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• 2003

지금까지 estrogen 호르몬이 유방암의 발생과 진전에 관여한다는 사실을 뒷받침 할 수 있는 여러 가지 증거가 제시되어 왔지만, 암화에 관여하고 있는 estrogen의 분자생물학적 작용기전에 대해서는 아직 명확히 알려져 있지 않다. 유방암 세포의 발암현상은 다양한 핵 수용체들과 이들 각각의 신호전달경로들 사이의 기능적 상호교류 (Functional Cross-talk)에 의해 조절되는 것으로 추측되고 있다. 그러므로, 유방암세포의 성장과 증식에 관여하는 신호전달경로중에서 estrogen의 작용을 조절할 수 있는 핵 수용체를 밝혀내고, 이러한 수용체와 estrogen receptor사이에 어떠한 기능적 상호교류가 일어나는지를 규명하는 것은 암화와 관련된 estrogen의 분자생물학적 작용기전을 이해하는 데 중요한 진전을 가져올 수 있다. 따라서 본 연구의 목적은 유방암세포 내에서 estrogen의 작용이 xenobiotic nuclear receptor에 의해 조절되는지를 규명하기 위하여, 두 종류의 유방암세포인 estrogen receptor가 발현되는 MCF-7 세포와 ER의 발현이 일어나지 않는 MDA-MB-231세포를 배양하여, 에스트로겐에 의해 전사가 촉진되는 보고유전자의 발현이 CAR, SXR, 그리고 PPAR${\gamma}$에 의해서 어떻게 영향을 받는지를 조사하고 그 결과를 간암세포에서의 반응과 비교 분석하였다. 최근에 보고된 연구결과와 일치하게, xenobiotic nuclear receptor가 간세포에서 일어나는 에스트로겐 수용체의 신호전달경로에 영향을 줄 수 있음을 확인하였다. PPAR${\gamma}$를 제외한 핵 수용체 CAR와 SXR은 ER의 전사활성 효과를 현저하게 또는 어느 정도 각각 감소시켰다. Hep G2세포에서와는 달리 유방암세포에서는 조사된 세가지의 xenobiotic 핵 수용체가 ER의 전사활성에 그다지 영향을 미치지 않거나 유방암세포의 종류와 각각의 수용체에 따라서 다소 촉진하는 경향을 나타내었다. MCF-7 세포에서는 CAR와 PPAR${\gamma}$을 제외한 SXR이 ER의 transactivation 효과를 약간 촉진한 반면 MDA-MB-231세포는 SXR을 제외한 CAR와 PPAR${\gamma}$에 의해 ER의 transactivation 효과가 약간 증가되는 경향을 보였다. 이러한 결과는 유방암세포에서는 CAR, SXR, PPAR${\gamma}$과 같은 xenobiotic nuclear receptor에 의한 ER transactivation 효과가 간암세포와는 다르게 나타나며, 유방암의 종류에 따라서 endogenous CAR, SXR, PPAR${\gamma}$수용체가 다르게 발현됨으로써 이들에 대한 반응이 서로 상이한 특징을 나타낼 수 있을 것으로 사료된다. 따라서 estrogen receptor에 의해 매개되는 estrogn의 전사활성조절기전이 표적세포에 따라 다른 경로를 포함 할 수 있음을 시사한다.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.228.2-229
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• 2003

Estrogen Receptor is a ligand-activated transcription factor. The concentration of the receptor is a major component that regulates expression of estrogen-responsive genes. We have studied mechanism of estrogen receptor alpha (ER${\alpha}$) downregulation by HIF-1 using HIF-1${\alpha}$/VP16 constructs. ER${\alpha}$ is known to be downregulated under hypoxic condition. Transcriptional response under hypoxia is mediated through Hypoxia-inducible factor-1 (HIF-1), a transcription factor that is usullaly degraded but stabilized under hypoxia. (omitted)

• Asian Pacific Journal of Cancer Prevention
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• 제16권6호
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• pp.2161-2166
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• 2015

Estrogen receptors (ERs) are steroid receptors located in the cytoplasm and on the nuclear membrane. The sequence similarities of human $ER{\alpha}$, mouse $ER{\alpha}$, rat $ER{\alpha}$, dog $ER{\alpha}$, and cat $ER{\alpha}$ are above 90%, but structures of $ER{\alpha}$ may different among species. Estrogen can be agonist and antagonist depending on its target organs. This hormone play roles in several diseases including breast cancer. There are variety of the relative binding affinity (RBA) of ER and estrogen species in comparison to $17{\beta}-estradiol$ (E2), which is a natural ligand of both $ER{\alpha}$ and $ER{\beta}$. The RBA of the estrogen species are as following: diethyl stilbestrol (DES) > hexestrol > dienestrol > $17{\beta}-estradiol$ (E2) > 17- estradiol > moxestrol > estriol (E3) >4-OH estradiol > estrone-3-sulfate. Estrogen mimetic drugs, selective estrogen receptor modulators (SERMs), have been used as hormonal therapy for ER positive breast cancer and postmenopausal osteoporosis. In the postgenomic era, in silico models have become effective tools for modern drug discovery. These provide three dimensional structures of many transmembrane receptors and enzymes, which are important targets of de novo drug development. The estimated inhibition constants (Ki) from computational model have been used as a screening procedure before in vitro and in vivo studies.

• Journal of Ginseng Research
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• 제43권4호
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• pp.527-538
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• 2019

Background: Ginsenoside Rg1 was shown to exert ligand-independent activation of estrogen receptor (ER) via mitogen-activated protein kinase-mediated pathway. Our study aimed to delineate the mechanisms by which Rg1 activates the rapid ER signaling pathways. Methods: ER-positive human breast cancer MCF-7 cells and ER-negative human embryonic kidney HEK293 cells were treated with Rg1 ($10^{-12}M$, $10^{-8}M$), $17{\beta}$-estradiol ($10^{-8}M$), or vehicle. Immunoprecipitation was conducted to investigate the interactions between signaling protein and ER in MCF-7 cells. To determine the roles of these signaling proteins in the actions of Rg1, small interfering RNA or their inhibitors were applied. Results: Rg1 rapidly induced $ER{\alpha}$ translocation to plasma membrane via caveolin-1 and the formation of signaling complex involving linker protein (Shc), insulin-like growth factor-I receptor, modulator of nongenomic activity of ER (MNAR), $ER{\alpha}$, and cellular nonreceptor tyrosine kinase (c-Src) in MCF-7 cells. The induction of extracellular signal-regulated protein kinase and mitogen-activated protein kinase kinase (MEK) phosphorylation in MCF-7 cells by Rg1 was suppressed by cotreatment with small interfering RNA against these signaling proteins. The stimulatory effects of Rg1 on MEK phosphorylation in these cells were suppressed by both PP2 (Src kinase inhibitor) and AG1478 [epidermal growth factor receptor (EGFR) inhibitor]. In addition, Rg1-induced estrogenic activities, EGFR and MEK phosphorylation in MCF-7 cells were abolished by cotreatment with G15 (G protein-coupled estrogen receptor-1 antagonist). The increase in intracellular cyclic AMP accumulation, but not Ca mobilization, in MCF-7 cells by Rg1 could be abolished by G15. Conclusion: Ginsenoside Rg1 exerted estrogenic actions by rapidly inducing the formation of ER containing signalosome in MCF-7 cells. Additionally, Rg1 could activate EGFR and c-Src ER-independently and exert estrogenic effects via rapid activation of membrane-associated ER and G protein-coupled estrogen receptor.

• Journal of Animal Science and Technology
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• 제45권4호
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• pp.523-528
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• 2003

본 연구는 PvuII PCR-RFLP를 이용하여 Yorkshire종 돼지에서 Estrogen Receptor의 유전적 다형과 산자수간의 관련성을 분석하기 위하여 수행되었다. 무창 돈사에서 사육중인 242두의 종빈돈으로부터 혈액을 채취하여 PvuII PCR- RFLP로 ER 유전자형을 결정하였다. ER 유전자 좌위에서 유전자 빈도는 각각 0.39(A)와 0.61(B)였다. ER 유전자형별 산자수에 대한 효과는 최소제곱평균을 설명하는 고정모형을 설정하여 추정하였다. 분석결과 복당 총산자수와 실산자수에서 특정 ER 대립유전자(B)에서 산자수 증진효과가 관찰되었다. 따라서 돼지 ER 좌위의 유전적 변이는 번식돈의 산자수 증대와 관련된 marker-assisted selection(MAS)에 응용될 수 있을 것으로 사료된다.

• Toxicological Research
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• 제20권3호
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• pp.205-211
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• 2004

Concern that some chemicals in our environment may affect human health by disrupt-ing normal endocrine function has prompted a research on interactions of environmental contaminants with steroid hormone receptor. Toxaphene and chlordane are among the 12 persistent organic pollutants identified by the United Nations Environment Programme as requiring urgent attention. We compared the estrogenic activity of two organochlorine pesticides, toxaphene and chlordane, at estrogen receptor a (ER$\alpha$) and estrogen receptor $\beta$ (ER$\beta$). Human hepatoma cells (HepG2) were transiently transfected with rat ER$\alpha$ or ER$\beta$ plus an estrogen-responsive complement C3-luciferase (C3-Luc) reporter gene. After transfection, cells were treated with various concentrations of toxaphene and chlordane to investigate agonism or antagonism of these chemicals. Both toxaphene and chlordane were potent agonists in HepG2 cells for ER$\alpha$. In contrast, these chemicals had a minimal agonist activity with ER$\beta$ and almost abolished 17$\beta$-estradiol-induced ER$\beta$-mediated activity. Therefore, toxaphene and chlordane behaved as an ER$\alpha$ agonist and an ER$\beta$ antagonist with estrogen-responsive reporter plasmid C3-Luc, and exposure to these organochlorine pesticides could have a crictical effect on normal endocrine function.

• Biomolecules & Therapeutics
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• 제13권4호
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• pp.227-231
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• 2005

The estrogen receptor (ER) is activated and degraded by estrogen. We have examined ER downregulation and activation under hypoxia mimetic conditions. Cobalt chloride induced ER downregulation at 24 h of treatment. This degradation involved hypoxia-inducible factor-1$\alpha$ (HIF-1$\alpha$) as examined by using a constitutively active form of HIF-1$\alpha$, HIF-1$\alpha$/VP16, constructed by replacing the transactivation domain of HIF-1$\alpha$ with that of VP16. Western blot analysis revealed that E2-induced ER downregulation was observed within ${\~}6h$, whereas HIF-1$\alpha$/VP16-induced ER degradation was observed within 12${\~}$20h. HIF-1$\alpha$/VP16 activated the transcription of estrogen-responsive reporter gene in the absence of estrogen. These results suggest that ER downregulation and activation under hypoxia maybe mediated in part by a HIP-1$\alpha$ expression.

• Asian-Australasian Journal of Animal Sciences
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• 제21권4호
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• pp.510-522
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• 2008

Our earlier studies showed that estrogen was involved in the regulation of fluid reabsorption in adult mouse efferent ductules (ED), through estrogen receptor (ER) ${\alpha}$ and $ER{\beta}$ by modulating gene expression of epithelial genes involved in ion homeostasis. However, little is known about the importance of $ER{\alpha}$ in the ED during postnatal development. Based on previous findings, we hypothesized that there should be a difference in the expression of epithelial ion transporters and anion producers in the ED of postnatal wild type (WT) and estrogen receptor ${\alpha}$ knockout (${\alpha}ERKO$) mice. Using absolute, comparative and semi-quantitative RT-PCR along with immunohistochemistry, we looked at expression levels of several genes in the ED across postnatal development. The presence of estrogen in the testicular fluid was indirectly ascertained by immunohistochemical detection of the P450 aromatase in the testis. There was no immunohistochemically detectable difference in the expression of P450 aromatase in the testes and ER${\beta}$ in the ED of WT and ${\alpha}$ERKO mice. ER${\alpha}$ was only detected in the ED of WT mice. The absence of ER${\alpha}$ in the ED of postnatally developing mice resulted in differential expression of mRNAs and/or proteins for carbonic anhydrase II, $Na^+/H^+$ exchanger 3, down-regulated in adenoma, cystic fibrosis transmembrane regulator, and $Na^+/K^+$ ATPase ${\alpha}$. Our data indicate that the absence of ER${\alpha}$ resulted in altered expression of an epithelial ion producer and transporters during postnatal development of mice. We conclude that the presence of ER${\alpha}$is important for regulation of the ED function during the prepubertal developmental and postpubertal period.