scholarly journals 17β-Estradiol Inhibits Iron Hormone Hepcidin Through an Estrogen Responsive Element Half-Site

Endocrinology ◽  
2012 ◽  
Vol 153 (7) ◽  
pp. 3170-3178 ◽  
Author(s):  
Qing Yang ◽  
Jinlong Jian ◽  
Stuart Katz ◽  
Steven B. Abramson ◽  
Xi Huang
Keyword(s):  
Hepg2 Cells ◽  
Gene Knockout ◽  
Negative Regulator ◽  
Estrogen Responsive Element ◽  
Gene Knockout Mice ◽  
17Β Estradiol ◽  
Responsive Element ◽  
Hepcidin Gene ◽  
Hepcidin Mrna ◽  
Half Site

Interaction of estrogen with iron at the systemic level is long suspected, but direct evidence linking the two is limited. In the present study, we examined the effects of 17β-estradiol (E2) on hepcidin, a key negative regulator of iron absorption from the liver. We found that transcription of hepcidin was suppressed by E2 treatment in human liver HuH7 and HepG2 cells, and this down-regulation was blocked by E2 antagonist ICI 182780. Chromatin immunoprecipitation, deletion, and EMSA detected a functional estrogen responsive element half-site that is located between −2474 and −2462 upstream from the start of transcription of the hepcidin gene. After cloning the human hepcidin promoter into the pGL3Luc-Reporter vector, luciferase activity was also down-regulated by E2 treatment in HepG2 cells. E2 reduced hepcidin mRNA in wild-type mice as well as in hemochromatosis Fe gene knockout mice. In summary, our data suggest that hepcidin inhibition by E2 is to increase iron uptake, a mechanism to compensate iron loss during menstruation. This mechanism may also contribute to increased iron stores in oral contraceptive users.

The Mask Mutation Identifies TMPRSS6 as an Essential Suppressor of Hepcidin Gene Expression, Required for Normal Uptake of Dietary Iron.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3-3 ◽  
Author(s):  
Ernest Beutler ◽  
Pauline Lee ◽  
Terri Gelbart ◽  
Xin Du ◽  
Bruce Beutler
Keyword(s):  
Iron Deficiency ◽  
Serine Protease ◽  
Positional Cloning ◽  
Negative Regulator ◽  
Mrna Levels ◽  
Dietary Iron ◽  
Iron Deficient ◽  
Total Body ◽  
Hepcidin Gene ◽  
Hepcidin Mrna

Abstract Hepcidin, the central negative regulator of iron absorption and iron release from macrophages, is upregulated by iron. Mutations in hemojuvelin, Hfe, transferrin receptor 2, and SMAD4 are known to prevent upregulation. Additionally, the bone morphogenetic proteins (BMPs), and the inflammatory cytokines IL-1 and IL-6 stimulate hepcidin gene activation. Downregulation of hepcidin is effected by anemia and hypoxia, but nothing is known of the mechanism through which this occurs. Here we describe the recessive ENU-induced phenotype Mask, so called because affected homozygotes developed regional alopecia in which truncal hair was shed while facial hair was retained. The Mask phenotype was found to be a manifestation of iron deficiency, and was eliminated by correcting the iron deficiency. When fed an iron deficient diet, mutant mice absorbed less iron than controls, as measured by total body 59Fe counting. After reaching a plateau total body counts stabilized, indicating that blood loss did not play a role in the iron deficiency. The level of liver hepcidin mRNA of iron deficient mice is normally greatly decreased; in contrast, the Mask mouse had high liver hepcidin mRNA levels. By positional cloning, we were able to ascribe the Mask phenotype to a splicing error in the Tmprss6 gene, which encodes a membrane-bound serine protease of previously unknown function. The mutation truncates the protein, eliminating the serine protease domain. Transfecting HepG2 cells to express the wildtype TMPRSS6 protein decreased baseline hepcidin reporter activity and almost entirely blunted the hepcidin inducing effect of IL-6, IL-1, hemojuvelin, and the BMPs. A construct encoding the Mask truncation mutant had diminished activity. Thus, TMPRSS6 powerfully down-regulates hepcidin gene transcription in the baseline state and prevents its upregulation by all known stimulators. TMPRSS6 is a non-redundant component of a hepcidin suppression pathway that exerts dominant effect over all known hepcidin inducing pathways, and is required for normal absorption of dietary iron.

scholarly journals Krüppel-Like Factor 9 Is a Negative Regulator of Ligand-Dependent Estrogen Receptor α Signaling in Ishikawa Endometrial Adenocarcinoma Cells

2007 ◽  
Vol 21 (12) ◽  
pp. 2988-3001 ◽  
Author(s):  
Michael C. Velarde ◽  
Zhaoyang Zeng ◽  
Jennelle R. McQuown ◽  
Frank A. Simmen ◽  
Rosalia C. M. Simmen
Keyword(s):  
Estrogen Receptor ◽  
Epithelial Cells ◽  
Promoter Region ◽  
Small Interfering Rna ◽  
Negative Regulator ◽  
Luciferase Reporter ◽  
Target Cells ◽  
Estrogen Responsive Element ◽  
Responsive Element ◽  
Interfering Rna

Abstract Estrogen and progesterone, acting through their respective receptors and other nuclear proteins, exhibit opposing activities in target cells. We previously reported that Krüppel-like factor 9 (KLF9) cooperates with progesterone receptor (PR) to facilitate P-dependent gene transcription in uterine epithelial cells. Here we evaluated whether KLF9 may further support PR function by directly opposing estrogen receptor (ER) signaling. Using human Ishikawa endometrial epithelial cells, we showed that 17β-estradiol (E2)-dependent down-regulation of ERα expression was reversed by a small interfering RNA to KLF9. Transcription assays with the E2-sensitive 4× estrogen-responsive element-thymidine kinase-promoter-luciferase reporter gene demonstrated inhibition of ligand-dependent ERα transactivation with ectopic KLF9 expression. E2 induced PR-A/B and PR-B isoform expression in the absence of effects on KLF9 levels. Addition of KLF9 small interfering RNA augmented E2 induction of PR-A/B while abrogating that of PR-B, indicating selective E2-mediated inhibition of PR-A by KLF9. Chromatin immunoprecipitation of the ERα minimal promoter demonstrated KLF9 promotion of E2-dependent ERα association to a region containing functional GC-rich motifs. KLF9 inhibited the recruitment of the ERα coactivator specificity protein 1 (Sp1) to the PR proximal promoter region containing a half-estrogen responsive element and GC-rich sites, but had no effect on Sp1 association to the PR distal promoter region containing GC-rich sequences. In vivo association of KLF9 and Sp1, but not of ERα with KLF9 or Sp1, was observed in control and E2-treated cells. Our data identify KLF9 as a transcriptional repressor of ERα signaling and suggest that it may function at the node of PR and ER genomic pathways to influence cell proliferation.

scholarly journals Estrogenic Activities of Fatty Acids and a Sterol Isolated from Royal Jelly

2008 ◽  
Vol 5 (3) ◽  
pp. 295-302 ◽  
Author(s):  
Kazu-Michi Suzuki ◽  
Yoichiro Isohama ◽  
Hiroe Maruyama ◽  
Yayoi Yamada ◽  
Yukio Narita ◽  
...  
Keyword(s):  
Royal Jelly ◽  
Binding Assay ◽  
Estrogenic Activity ◽  
Luminal Epithelium ◽  
Concomitant Treatment ◽  
Decenoic Acid ◽  
Estrogen Responsive Element ◽  
17Β Estradiol ◽  
Responsive Element ◽  
Mcf 7

We have previously reported that royal jelly (RJ) from honeybees (Apis mellifera) has weak estrogenic activity mediated by interaction with estrogen receptors that leads to changes in gene expression and cell proliferation. In this study, we isolated four compounds from RJ that exhibit estrogenic activity as evaluated by a ligand-binding assay for the estrogen receptor (ER) β. These compounds were identified as 10-hydroxy-trans-2-decenoic acid, 10-hydroxydecanoic acid,trans-2-decenoic acid and 24-methylenecholesterol. All these compounds inhibited binding of 17β-estradiol to ERβ, although more weakly than diethylstilbestrol or phytoestrogens. However, these compounds had little or no effect on the binding of 17β-estradiol to ERα. Expression assays suggested that these compounds activated ER, as evidenced by enhanced transcription of a reporter gene containing an estrogen-responsive element. Treatment of MCF-7 cells with these compounds enhanced their proliferation, but concomitant treatment with tamoxifen blocked this effect. Exposure of immature rats to these compounds by subcutaneous injection induced mild hypertrophy of the luminal epithelium of the uterus, but was not associated with an increase in uterine weight. These findings provide evidence that these compounds contribute to the estrogenic effect of RJ.

scholarly journals Single-Chain Estrogen Receptors (ERs) Reveal that the ERα/β Heterodimer Emulates Functions of the ERα Dimer in Genomic Estrogen Signaling Pathways

2004 ◽  
Vol 24 (17) ◽  
pp. 7681-7694 ◽  
Author(s):  
Xiaodong Li ◽  
Jing Huang ◽  
Ping Yi ◽  
Robert A. Bambara ◽  
Russell Hilf ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Mammalian Cells ◽  
Target Genes ◽  
Estrogen Receptor Α ◽  
Estrogen Signaling ◽  
Single Chain ◽  
Estrogen Responsive Element ◽  
17Β Estradiol ◽  
Responsive Element

ABSTRACT The effects of estrogens, particularly 17β-estradiol (E2), are mediated by estrogen receptor α (ERα) and ERβ. Upon binding to E2, ERs homo- and heterodimerize when coexpressed. The ER dimer then regulates the transcription of target genes through estrogen responsive element (ERE)-dependent and -independent pathways that constitute genomic estrogen signaling. Although ERα and ERβ have similar ERE and E2 binding properties, they display different transregulatory capacities in both ERE-dependent and -independent signaling pathways. It is therefore likely that the heterodimerization provides novel functions to ERs by combining distinct properties of the contributing partners. The elucidation of the role of the ER heterodimer is critical for the understanding of physiology and pathophysiology of E2 signaling. However, differentially determining target gene responses during cosynthesis of ER subtypes is difficult, since dimers formed are a heterogeneous population of homo- and heterodimers. To circumvent the pivotal dimerization step in ER action and hence produce a homogeneous ER heterodimer population, we utilized a genetic fusion strategy. We joined the cDNAs of ERα and/or ERβ to produce single-chain ERs to simulate the ER homo- and heterodimers. The fusion ERs interacted with ERE and E2 in a manner similar to that observed with the ER dimers. The homofusion receptors mimicked the functions of the parent ER dimers in the ERE-dependent and -independent pathways in transfected mammalian cells, whereas heterofusion receptors emulated the transregulatory properties of the ERα dimer. These results suggest that ERα is the functionally dominant partner in the ERα/β heterodimer.

scholarly journals 17β-estradiol binding to ERα promotes the progression of prolactinoma through estrogen-response element-induced CaBP-9k up-regulation

2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Jun Liu ◽  
Hao Han ◽  
Wenpeng Lu ◽  
Gaoyang Fan
Keyword(s):  
Cell Apoptosis ◽  
Cell Counting ◽  
Transcriptional Level ◽  
Calbindin D9k ◽  
Estrogen Response ◽  
Estrogen Responsive Element ◽  
Gene Reporter Assay ◽  
17Β Estradiol ◽  
Responsive Element ◽  
Luciferase Gene Reporter Assay

Abstract 17β-estradiol (E2) is considered to be an important instigator of prolactinoma, and can positively regulate the expression of calbindin-D9k (CaBP-9k) which contains an estrogen responsive element (ERE) via estrogen receptors (ERs). However, the detailed mechanism of E2 in promoting CaBP-9k expression and their roles in prolactinoma progression remain unclear. Here, we aimed to characterize it. The luciferase gene reporter assay with luc-ERE transfection showed that E2 treatment significantly enhanced the transcriptional level of CaBP-9k, whereas CaBP-9k activity was reduced when GH3 and MMQ cells were treated with AZD9496, an antagonist of ERα. E2 treatment increased the protein expressions of CaBP-9k and ERα but not ERβ, whereas this effect was also abolished when cells were treated with AZD9496. Besides, immunoprecipitation (IP) and immunofluorescence assays demonstrated that CaBP-9k could directly interact with ERα not ERβ, and Chromatin IP (ChIP) assay showed that ERα could bind to ERE of the CaBP-9k promoter. Moreover, cell counting kit-8 (CCK-8) and flow cytometry assays showed that E2 treatment significantly enhanced cell viability and inhibited cell apoptosis, but these effects were all abolished when ERα was down-regulated by short hairpin RNA (shRNA) or inhibited by AZD9496, as well as CaBP-9K suppression in both GH3 and MMQ cell lines. Taken together, these findings indicated that E2 stimulation promoted prolactin cell proliferation and inhibited cell apoptosis through ERα-induced CaBP-9k up-regulation, which then accelerated the advanced progression of prolactinoma.

Detrimental implication of B1 receptors in myocardial ischemia: evidence from pharmacological blockade and gene knockout mice

2002 ◽  
Vol 2 (6) ◽  
pp. 815-822 ◽  
Author(s):  
Caroline Lagneux ◽  
Michael Bader ◽  
João B. Pesquero ◽  
Pierre Demenge ◽  
Christophe Ribuot
Keyword(s):  
Myocardial Ischemia ◽  
Knockout Mice ◽  
Gene Knockout ◽  
B1 Receptors ◽  
Gene Knockout Mice ◽  
Pharmacological Blockade
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