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

• Natural Product Sciences
• /
• 제25권1호
• /
• pp.28-33
• /
• 2019

A popular approach for the study of estrogen receptor ${\alpha}$ inhibition is to investigate the protein-protein interaction between the estrogen receptor (ER) and the coactivator surface. In our study, we investigated phytochemicals from Rubus coreanus that were able to disrupt $ER{\alpha}$ and coactivator interaction with an $ER{\alpha}$ antagonist. The E-screen assay and molecular docking analysis were performed to evaluate the effects of the estrogenic activity of R. coreanus extract and its constituents on the MCF-7 human breast cancer cell line. At $100{\mu}g/mL$, R. coreanus extract significantly stimulated cell proliferation ($574.57{\pm}8.56%$). Sanguiin H6, which was isolated from R. coreanus, demonstrated the strongest affinity for the $ER{\alpha}$ coactivator-binding site in molecular docking analysis, with a binding energy of -250.149. The initial results of the study indicated that sanguiin H6 contributed to the estrogenic activity of R. coreanus through the activation of the $ER{\alpha}$ coactivator-binding site.

• BMB Reports
• /
• 제42권8호
• /
• pp.516-522
• /
• 2009

SH2D4A, comprising a single SH2 domain, is a novel protein of the SH2 signaling protein family. We have previously demonstrated SH2D4A is expressed ubiquitously in various tissues and is located in the cytoplasm. In this study we investigated the function of SH2D4A in human embryonic kidney (HEK) 293 cells using interaction analysis, cell proliferation assays, and kinase activity detection. SH2D4A was found to directly bind to estrogen receptor $\alpha$ (ER$\alpha$), and prevent the recruitment of phospholipase C-$\gamma$ (PLC-$\gamma$) to ER$\alpha$. Moreover, we observed its inhibitory effects on estrogen-induced cell proliferation, involving the protein kinase C (PKC) signaling pathway. Together, these findings suggested that SH2D4A inhibited cell proliferation by suppression of the ER$\alpha$/PLC-$\gamma$/PKC signaling pathway. SH2D4A may be useful for the development of a new anti-cancer drug acting as an ER signaling modulator.

• 한국발생생물학회지:발생과생식
• /
• 제10권4호
• /
• pp.255-261
• /
• 2006

일부 식물성 에스트로겐(phytoestrogen)의 경우, 긍정적인 효과를 갖는 것으로 보이지만, 대부분의 내분비계 장애 물질(endocrine disruptor 또는 endocrine disrupting compound, EDC)은 노출된 개체의 내분비계를 교란시켜 인간이나 야생 동물의 건강에 해로운 것으로 알려져 있다. 선행 연구에서 본 연구자들은 사춘기 전에 단기간으로 식물성 에스트로겐인 genistein(GS)을 투여했을 때 암컷 흰쥐의 생식계가 활성화되어 조기 사춘기가 유도되지만, 플라스틱 가소제인 di(2-ethyl hexyl)phthalate(DEHP)를 투여했을 때 반대로 생식계의 불활성화가 유도되어 사춘기 지연이 초래됨을 보고하였다. 본 연구에서는 사춘기전 GS 또는 DEHP 투여가 흰쥐 난소와 자궁에서의 성적인 성숙 상태를 반영하는 에스트로겐 수용체($ER\;{\alpha}$ and $ER\;{\beta}$)와 LH 수용체(LHR) 발현에 미치는 효과를 조사하였다. GS(100 mg/kg/day i.p.)를 생후 25일부터 사춘기 개시의 지표인 최초의 질구 개방(vaginal opening, VO)이 일어나는 날까지 투여하고 다음 날(day 32) 희생시켰다. 유사하게, DEHP(100 mg/kg/day i.p.)를 생후 25일부터 대조군(corn oil $200\;{\mu}L$)에서 최초 질구 개방(vaginal opening, VO)이 일어나는 날까지 투여하고 다음 날(day 36) 희생시켰다. 희생 직후 난소와 자궁의 total RNA를 추출하여 각 호르몬 수용체들의 전사 수준을 측정하기 위해 정량적인 RT-PCR을 수행하였다. GS 투여에 의해 자궁에서의 $ER\;{\alpha}$, $ER\;{\beta}$ 그리고 LHR mRNA 수준 모두 대조군에 비해 유의하게 증가하였다. GS군의 난소에서는 LHR 발현이 유의하게 증가하였으나 $ER\;{\alpha}$와 $ER\;{\beta}$의 발현은 증가하는 경향만을 보였다. 한편, DEHP군에서는 난소와 자궁에서의 $ER\;{\alpha}$, $ER\;{\beta}$ 그리고 LHR mRNA 수준은 모두 대조군에 비해 유의하게 감소하였다. 사춘기 전의 암컷 흰쥐의 난소와 자궁에서 성숙과 관련된 생식호르몬 수용체들의 발현 변화는 이들 조직의 무게와 해부학적인 변화, 그리고 혈중 생식호르몬들의 수준 등 사춘기 과정에서의 표현형적인 측면 변화-2차 성징-들을 반영하는 것으로 추정된다.

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

• Journal of Korean Neurosurgical Society
• /
• 제50권5호
• /
• pp.415-419
• /
• 2011

Objective : The purpose of this study was to investigate the possible association of estrogen receptor alpha ($ER{\alpha}$) gene polymorphisms in a cohort of degenerative spondylolisthesis (DS) patients. Methods : Accordingly, the authors examined the association between DS and $ER{\alpha}$ gene polymorphisms in 174 patients diagnosed with DS. The $Pvu$ $II$ and $Xba$ $I$ polymorphisms, bone mineral density at the lumbar spine and femoral neck, and biochemical markers were analyzed and compared in the 174 patients with DS and 214 patients with spinal stenosis (SS). Results : A comparison of genotype frequencies in DS and SS patients revealed a significant difference for the $Pvu$ $II$ polymorphism only ($p$=0.0452). No significant difference was found between these two groups with respect to the $Xba$ $I$ polymorphism, BMD or biochemical markers. No significant association was found between the$Pvu$ $II$ polymorphism of $ER{\alpha}$ and BMD, vertebral slip or biochemical markers in patients with DS. Conclusion : These results suggest that the $ER{\alpha}$ gene polymorphism using $Pvu$ $II$ restriction enzyme influences the prevalence of DS.

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권7호
• /
• pp.4049-4052
• /
• 2013

Resistance to chemotherapy treatment, which may lead to limited efficacy of systemic therapy in breast cancer patients, is multifactorial. Among the mechanisms of resistance to chemotherapy treatment, there are those closely related to estrogen receptor ${\alpha}$, P-glycoprotein, multidrug resistance-related protein, glutathione S-transferase pi and topoisomerase-II. $ER{\alpha}$ is ligand-activated transcription factor that regulates gene expression and plays a critical role in endocrine signaling. In previous preclinical and clinical studies, positive $ER{\alpha}$ expression in breast cancer cells was correlated with decreased sensitivity to chemotherapy. This article reviews current knowledge on the predictive value of $ER{\alpha}$ with regard to response to chemotherapy. Better understanding of its role may facilitate patient selection of therapeutic regimens and lead to optimal clinical outcomes.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권2호
• /
• pp.451-457
• /
• 2012

One decade early onset of the breast cancer in Iranian females was reported but the basis of the observed difference has remained unclear and difference in gene silencing by epigenetic processes is suggested. Hence, this study was sought to map the methylation status of estrogen receptor (ER) gene CpG islands and its impact on clinicopathological factors of triple negative and non-triple negative ductal cell carcinoma of the breast in Iranian females. Surgically resected formalin-fixed paraffin-embedded breast tissues from sixty Iranian women with confirmed invasive ductal carcinoma were assessed by methylation-specific PCR using primer sets encompassing some of the 29 CpGs across the ER gene CpG island. The estrogen and progesterone receptors, Her-$2^+$ overexpression, and nuclear accumulation of P53 were examined using immunohistochemistry (IHC). Methylated ER3, ER4, and ER5 were found in 41.7, 11.3, and 43.3% of the samples, respectively. Significantly higher methylation of ER4 was found in the tumors with nuclear accumulation of P53, and significantly higher methylation of ER5 was found in patients with lymph node involvement and tumor with bigger size or higher grades. Furthermore, significantly higher rate of ER5 methylation was found in patients with Her-$2^+$ tumors and in postmenopausal patients with $ER^-$, $PgR^-$, or $ER^-/PgR^-$ tumors. However, no significant difference in ERs methylation status was found between triple negative and non-triple negative tumors in pre- and postmenopausal patients. Findings revealed that aberrant hypermethylation of the ER-alpha gene frequently occurs in Iranian women with invasive ductal cell carcinoma of the breast. However, methylation of different CpG islands produced a diverse impact on the prognosis of breast cancer, and ER5 was found to be the most frequently methylated region in the Iranian women, and could serve as a marker of poor prognosis.

• 대한의생명과학회지
• /
• 제15권3호
• /
• pp.179-185
• /
• 2009

In our previous report, we showed that $PPAR{\gamma}$ does not influence adipogenesis in females with functioning ovaries, indicating that $PPAR{\gamma}$ activity on adipogenesis is associated with sex-related factors. Among the sex-related factors, estrogen has been recognized as a major factor in inhibiting adiposgenesis in females. Thus, we hypothensized that $17{\beta}$-estradiol (E) inhibits 3T3-L1 cell adipogenesis by preventing $PPAR{\gamma}$ activity. E decreased triglyceirde accumulation in differentiated 3T3-L1 cells compared with control group. E also decreased the expression of $PPAR{\gamma}$ mRNA as well as $PPAR{\gamma}$ dependent adipocyte-specific genes, such as adipocyte fatty acid binding protein and tumor necrosis factor $\alpha$. In addition, E not only decreased luciferase reporter activity by $PPAR{\gamma}$, but also transfection of estrogen receptor $\alpha$ ($ER{\alpha}$) or $ER{\beta}$ led to decreases in $PPAR{\gamma}$ reporter gene activation. Moreover, E-activated ERs significantly decreased the luciferase reporter gene activation induced by $PPAR{\gamma}$ transfection, suggesting that estrogen-activated ERs inhibit $PPAR{\gamma}$-dependent transactivation. Accordingly, our results demonstrate that E inhibits the action of $PPAR{\gamma}$ on adipogenesis through E activated ER, providing evidence that lack of estrogen may potentiate $PPAR{\gamma}$ action on adipogenesis.

• Journal of Microbiology and Biotechnology
• /
• 제16권9호
• /
• pp.1453-1458
• /
• 2006

PKR-like endoplasmic reticulum (ER) kinase (PERK) is a type I transmembrane ER-resident protein containing a cytoplasmic catalytic domain with a Ser/Thr kinase activity, which is most closely related to the eukaryotic translation initiation factor-$2{\alpha}$ ($eIF2{\alpha}$) kinase PKR involved in the antiviral defense pathway by interferon. We cloned and expressed the PERK C-terminal kinase domain (cPERK) in Escherichia coli. Like PERK activation in cells under ER stress, wild-type cPERK underwent autophosphorylation when overexpressed in E. coli, whereas the cPERK(K621M) with a methionine substitution for the lysine at amino acid 621 lost the autophosphorylation activity. The activated form cPERK which was purified to near homogeneity, formed an oligomer and was able to trans-phosphorylate specifically its cellular substrate $eIF2{\alpha}$. Two-dimensional phosphoamino acids analysis revealed that phosphorylation of cPERK occurs at the Ser and Thr residues. The functionally active recombinant cPERK, and its inactive mutant should be useful for the analysis of biochemical functions of PERK and for the determination of their three-dimensional structures.