Regulation Of Estrogen Receptor Research Articles

TRPM4 is overexpressed in breast cancer associated with estrogen response and epithelial-mesenchymal transition gene sets.

Ion channels form an important class of drug targets in malignancies. Transient receptor potential cation channel subfamily M member 4 (TRPM4) plays oncological roles in various solid tumors. Herein, we examined TRPM4 protein expression profile by immunohistochemistry (IHC) in breast cancer cases compared with normal breast ducts, its association with clinico-demographical parameters, and its potential function in breast cancers by Gene Set Enrichment Analysis (GSEA). Data-mining demonstrated that TRPM4 transcript levels were significantly higher in The Cancer Genome Atlas series of breast cancer cases (n = 1,085) compared with normal breast tissues (n = 112) (p = 1.03 x 10−11). Our IHC findings in tissue microarrays showed that TRPM4 protein was overexpressed in breast cancers (n = 83/99 TRPM4+; 83.8%) compared with normal breast ducts (n = 5/10 TRPM4+; 50%) (p = 0.022). Higher TRPM4 expression (median frequency cut-off) was significantly associated with higher lymph node status (N1-N2 vs N0; p = 0.024) and higher stage (IIb-IIIb vs I-IIa; p = 0.005). GSEA evaluation in three independent gene expression profiling (GEP) datasets of breast cancer cases (GSE54002, n = 417; GSE20685, n = 327; GSE23720, n = 197) demonstrated significant association of TRPM4 transcript expression with estrogen response and epithelial-mesenchymal transition (EMT) gene sets (p<0.01 and false discovery rate<0.05). These gene sets were not enriched in GEP datasets of normal breast epithelium cases (GSE10797, n = 5; GSE9574, n = 15; GSE20437, n = 18). In conclusion, TRPM4 protein expression is upregulated in breast cancers associated with worse clinico-demographical parameters, and TRPM4 potentially regulates estrogen receptor signaling and EMT progression in breast cancer.

Apigenin Inhibits Histamine-Induced Cervical Cancer Tumor Growth by Regulating Estrogen Receptor Expression.

Apigenin is a natural flavone with anti-inflammatory and antioxidant properties and antitumor abilities against several types of cancers. Previous studies have found that the antitumor effects of apigenin may be due to its similar chemical structure to 17β-estradiol (E2), a main kind of estrogen in women. However, the precise mechanism underlying the antitumor effects of apigenin in cervical cancer remains unknown. On the other hand, there is increasing evidence that describes a histamine role in cancer cell proliferation. In this study, we examined whether apigenin can attenuate the effects of histamine on tumors by regulating the expression level of estrogen receptors (ERs) to inhibit cervical cancer growth. Our in vitro data indicates that apigenin inhibited cell proliferation in a dose-dependent manner in human cervical cancer cells (HeLa), while histamine shows the opposite effects. After that, the xenograft model was established to explore the antitumor effects of apigenin in vivo, the results show that apigenin inhibited cervical tumor growth by reversing the abnormal ER signal in tumor tissue which was caused by histamine. We also demonstrate that apigenin inhibited cell proliferation via suppressing the PI3K/Akt/mTOR signaling pathway. Collectively, our results suggest that apigenin may inhibit tumor growth through the ER-mediated PI3K/Akt/mTOR pathway and that it can also attenuate the effects of histamine on tumors.

Sex‐Specific Estrogen Regulation of Hypothalamic Astrocyte Estrogen Receptor and Glycogen Metabolic Enzyme Protein Expression, and Glycogen Content in Rats

Brain astrocytes are implicated in estrogenic neuroprotection against bio‐energetic insults, which may involve their glycogen energy reserve. Forebrain estrogen receptor (ER)‐alpha (ERα) and ‐beta (ERβ) exert differential control of glycogen metabolic enzyme [glycogen synthase (GS); phosphorylase (GP)] expression in hypoglycemic male versus female rats. Studies were conducted using a rat hypothalamic astrocyte primary culture model along with selective ER agonists to investigate the premise that estradiol (E2) exerts sex‐dimorphic control over astrocyte glycogen mass and metabolism. Female astrocyte GS and GP profiles are more sensitive to E2 stimulation than the male. E2 did not regulate expression of phospho‐GS (inactive enzyme form) in either sex. Data also show that transmembrane G protein‐coupled ER‐1 (GPER) signaling is implicated in E2 control of GS profiles in each sex, and regulates GP expression in females. E2 increases total 5′‐AMK‐activated protein kinase (AMPK) protein in female astrocytes, but stimulated pAMPK (active form) expression with equivalent potency via GPER in females and ERα in males. In female astrocytes, ERα protein was up‐regulated at a lower E2 concentration and over a broader dosage range compared to males, whereas ERβ was increased after exposure to 1–10 nM versus 100 pM E2 levels in females and males, respectively. GPER profiles were stimulated by E2 in female, but not male astrocytes. E2 increased astrocyte glycogen content in female, but not male astrocytes; selective ERβ or ERα stimulation elevated glycogen levels in the female and male, respectively. Outcomes imply that dimorphic astrocyte protein and glycogen responses to E2 may reflect, in part, differential steroid induction of ER variant expression and/or regulation of post‐receptor signaling in each sex.Support or Funding InformationThis research was supported by NIH DK 109382.

Abstract P1-21-03: Unique estrogen receptor alpha turnover, regulation and targeting in invasive lobular breast carcinoma

Abstract Invasive lobular breast carcinoma (ILC) accounts for 10-15% of breast cancers diagnosed annually. Evidence suggests that endocrine treatment response might differ between invasive ductal carcinoma (IDC) and ILC, and that patients with ILC have worse long-term survival. ILCs are more likely to be estrogen receptor alpha (ER/ERα) positive (90-95%) compared to IDCs (60-70%). We investigated whether there are differences in ER protein steady state levels and/or turn-over rates in ILC that might explain differences in response to endocrine therapy. Analysis of the TCGA dataset revealed lower levels of ESR1 mRNA (P = 0.002) and ERα protein (P = 0.038) in ER+ ILC (n = 137) compared to ER+ IDC (n = 554). Supporting this observation, analysis of tumors from patients treated at UPMC Magee-Women’s Hospital (ILC, n = 143; IDC, n = 877), showed lower ESR1 mRNA (P &amp;lt; 0.005) in ILC and similar ERα protein levels in both subtypes. In both datasets, the correlation between ESR1 mRNA and ERα protein was significantly weaker in ILC suggesting differential post-transcriptional regulation of ER. This was confirmed in in vitro studies showing 17β-estradiol (E2) decreased the rate of degradation and increased half-life of ERα in MDA-MB-134-VI and SUM44PE ILC cell lines, whereas the opposite was observed in IDC cell lines. Further analysis of MDA-MB-134-VI cells revealed that E2 downregulated ubiquitination pathway genes and failed to induce ubiquitination of ERα. To determine potential clinical relevance of our findings, we evaluated the effect of two selective estrogen receptor down-regulators (SERDs) on ERα turnover and E2-induced proliferation of IDC and ILC cell lines. While fulvestrant and AZD9496, a novel orally bioavailable SERD, showed similar effects in IDC cell lines, AZD9496 was less effective than fulvestrant in decreasing ERα protein stability and E2-induced proliferation in ILC cells. Furthermore, AZD9496 exhibited partial agonist activity in growth and gene expression assays in the absence of ligand. Collectively, our data provide evidence for distinct ligand-induced ERα turnover in ILC cell lines. In addition, the novel SERD AZD9496 displays partial agonist activity in ILC cells, and further studies should address whether these observations are causally linked. These results provide a strong rationale for inclusion of ILC subgroups into preclinical and clinical testing of SERDs. Citation Format: Jennifer M Atkinson, Sreeja Sreekumar, Kevin M Levine, Matthew J Sikora, Jian Chen, David J Dabbs, Carolin Meier, Ahmed Basudan, Nilgun Tasdemir, David Boone, Priscilla F McAuliffe, Rachel C Jankowitz, Adrian V Lee, Steffi Oesterreich. Unique estrogen receptor alpha turnover, regulation and targeting in invasive lobular breast carcinoma [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-21-03.

MiR-203 regulates estrogen receptor α and cartilage degradation in IL-1β-stimulated chondrocytes

Estrogen receptor α (ERα) plays important roles in the etiology of osteoarthritis (OA), in which cartilage degradation and cellular inflammation are involved. MiR-203 is reported to direct target ERα, but its roles in chondrocytes remain uncovered. In this study, ELISA showed that the level of estrogen hormone in the serum of postmenopausal OA patients was significantly lower than the one in patients without OA. RT-PCR revealed that the expression level of miR-203 was significantly up-regulated in the OA patients. Furthermore, western blotting demonstrated the lower expression levels of aggrecan, Col2A1, and ERα in the isolated articular cartilage tissues of OA patients. To decipher the association between ERα and miR-203 in the pathogenesis of OA, IL-1β stimulated cultured chondrocyte cell model was established to measure the cell viability, cellular inflammation, cell injury, as well as cartilage degradation with miR-203 inhibitor and ERα. The results showed that IL-1β stimulation induced the expression of miR-203, which promoted cellular inflammation and cell injury, and caused down-regulation of aggrecan and Col2A1. Luciferase assay indicated the direct binding between miR-203 and ERα, and ERα-specific SiRNA inversed the protective role of miR-203 inhibitor in the progression of OA in the cell system. MiR-203 is critical in the onset and progression of OA, at least in part, caused by estrogen deficiency and ERα instability in OA patients, providing a novel therapeutic target for the treatment of OA.

Sex-dependent regulation of estrogen receptor beta in human colorectal cancer tissue and its relationship with clock genes and VEGF-A expression.

The incidence of colorectal cancer (CRC) shows a sex-dependent difference in humans. The aim of this study was to analyze estrogen receptor beta mRNA (ERbeta) expression in patients with CRC with respect to their gender and clinicopathological features. Since cancer progression is accompanied by tumor vascularization, VEGF-A (vascular endothelial growth factor A) transcription was analyzed along with ERbeta mRNA. ERbeta mRNA was also correlated with the expression of clock genes, which are known to influence the cell cycle. ERbeta mRNA expression in females with CRC showed an inverse association with increasing tumor staging that was not observed in males. Lower levels of ERbeta mRNA were observed in females with a higher clinical stage compared with those with earlier-stage tumors. ERbeta mRNA expression showed a significant positive correlation with mRNA of clock genes period 2 and cryptochrome 2 in healthy but not in cancerous tissue in males. Expression of VEGF-A mRNA showed a negative correlation with ERbeta mRNA after splitting of the cohort according to gender and nodus involvement. We propose that gender differences in ERbeta mRNA expression in tumors during the early stages of CRC can partially explain the lower occurrence of CRC in females compared with males.

ESR1-Stabilizing Long Noncoding RNA TMPO-AS1 Promotes Hormone-Refractory Breast Cancer Progression.

Acquired endocrine therapy resistance is a significant clinical problem for breast cancer patients. In recent years, increasing attention has been paid to long noncoding RNA (lncRNA) as a critical modulator for cancer progression. Based on RNA-sequencing data of breast invasive carcinomas in The Cancer Genome Atlas database, we identified thymopoietin antisense transcript 1 (TMPO-AS1) as a functional lncRNA that significantly correlates with proliferative biomarkers. TMPO-AS1 positivity analyzed by in situ hybridization significantly correlates with poor prognosis of breast cancer patients. TMPO-AS1 expression was upregulated in endocrine therapy-resistant MCF-7 cells compared with levels in parental cells and was estrogen inducible. Gain and loss of TMPO-AS1 experiments showed that TMPO-AS1 promotes the proliferation and viability of estrogen receptor (ER)-positive breast cancer cells in vitro and in vivo Global expression analysis using a microarray demonstrated that TMPO-AS1 is closely associated with the estrogen signaling pathway. TMPO-AS1 could positively regulate estrogen receptor 1 (ESR1) mRNA expression by stabilizing ESR1 mRNA through interaction with ESR1 mRNA. Enhanced expression of ESR1 mRNA by TMPO-AS1 could play a critical role in the proliferation of ER-positive breast cancer. Our findings provide a new insight into the understanding of molecular mechanisms underlying hormone-dependent breast cancer progression and endocrine resistance.

Tamoxifen in Duchenne muscular dystrophy (TAMDMD): study protocol for a multicenter, randomized, placebo-controlled, double-blind phase 3 trial

BackgroundDuchenne muscular dystrophy (DMD) is an inherited neuromuscular disorder of childhood with a devastating disease course. Several targeted gene therapies and molecular approaches have been or are currently being tested in clinical trials; however, a causative therapy is still not available and best supportive care is limited to oral glucocorticoids with numerous long-term side effects. Tamoxifen is a selective estrogen receptor regulator, and shows antioxidant actions and regulatory roles in the calcium homeostasis besides its antitumor activity. In a mouse model of DMD, oral tamoxifen significantly improved muscle strength and reduced muscle fatigue. This multicenter, randomized, double-blind, placebo-controlled phase III trial aims to demonstrate safety and efficacy of tamoxifen over placebo in pediatric patients with DMD. After completion of the double-blind phase, an open-label extension of the study will be offered to all participants.Methods/designAt least 71 ambulant and up to 20 nonambulant patients with DMD are planned to be enrolled at multiple European sites. Patients will be randomly assigned to receive either tamoxifen 20 mg or placebo daily over 48 weeks. In the open-label extension phase, all patients will be offered tamoxifen for a further 48 weeks. The primary endpoint of the double-blind phase is defined as the change of the D1 domain of the motor function measure in ambulant patients or a change of the D2 domain in nonambulant patients under tamoxifen compared to placebo. Secondary outcome measures include change in timed function tests, quantitative muscle testing, and quantitative magnetic resonance imaging of thigh muscles. Laboratory analyses including biomarkers of tamoxifen metabolism and muscle dystrophy will also be assessed.DiscussionThe aim of the study is to investigate whether tamoxifen can reduce disease progression in ambulant and nonambulant patients with DMD over 48 weeks. Motor function measures comprise the primary endpoint, whereas further clinical and radiological assessments and laboratory biomarkers are performed to provide more data on safety and efficacy. An adjacent open-label extension phase is planned to test if earlier initiation of the treatment with tamoxifen (verum arm of double-blind phase) compared to a delayed start can reduce disease progression more efficiently.Trial registrationClinicalTrials.gov, NCT03354039. Registered on 27 November 2017.

The Osteoprotective Effects Of Kaempferol: The Evidence From In Vivo And In Vitro Studies.

Kaempferol is a dietary bioflavonoid ubiquitously found in various types of plant. It possesses a wide range of medicinal properties suggesting its potential clinical utility that requires further investigation. The present review intends to highlight the efficacy of kaempferol and its molecular mechanisms of action in regulating bone metabolism. Many reports have acknowledged the bone-protecting property of kaempferol and kaempferol-containing plants using in vitro and in vivo experimental models. Kaempferol supplementation showed bone-sparing effects in newborn rats, glucocorticoid-induced and ovariectomy-induced osteoporotic models as well as bone fracture models. It achieves the bone-protective effects by inhibiting adipogenesis, inflammation, oxidative stress, osteoclastic autophagy and osteoblastic apoptosis while activating osteoblastic autophagy. The anti-osteoporotic effects of kaempferol are mediated through regulation of estrogen receptor, bone morphogenetic protein-2 (BMP-2), nuclear factor-kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and mammalian target of rapamycin (mTOR) signaling pathways. In summary, kaempferol exhibits beneficial effects on skeleton, thus is potentially effective for the prophylaxis and treatment of osteoporosis.

G protein-coupled estrogen receptor in colon function, immune regulation and carcinogenesis.

Estrogens play important roles in the development and progression of multiple tumor types. Accumulating evidence points to the significance of estrogen action not only in tumors of hormonally regulated tissues such as the breast, endometrium and ovary, but also in the development of colorectal cancer (CRC). The effects of estrogens in physiological and pathophysiological conditions are mediated by the nuclear estrogen receptors α and β, as well as the membrane-bound G protein-coupled estrogen receptor (GPER). The roles of GPER in CRC development and progression, however, remain poorly understood. Studies on the functions of GPER in the colon have shown that this estrogen receptor regulates colonic motility as well as immune responses in CRC-associated diseases, such as Crohn’s disease and ulcerative colitis. GPER is also involved in cell cycle regulation, endoplasmic reticulum stress, proliferation, apoptosis, vascularization, cell migration, and the regulation of fatty acid and estrogen metabolism in CRC cells. Thus, multiple lines of evidence suggest that GPER may play an important role in colorectal carcinogenesis. In this review, we present the current state of knowledge regarding the contribution of GPER to colon function and CRC.

Abstract 5203: Segregating activities of the estrogen receptor in gene regulation

Abstract Upon stimulation with its ligand estradiol (E2), the estrogen receptor (ER) obviously can induce both transcriptional activation and repression in breast cancer cells. Although the mechanism of gene activation has been extensively scrutinized, how ER targets are turned off is generally overlooked. Some theories have been proposed to explain the trans-suppression process, such as engagement of corepressors, physiological squelch of coactivators, or decommission of RNA Polymerase II, etc. However, none of these models really elucidate the intrinsic and external factors that segregate ER activities in transcriptional regulation. In this study, we identified a functional domain of ER, which is specifically required for E2-mediated gene repression. While the DNA-binding domain (DBD) was essential for the overall response to E2, deletion of AF2 fragment at C-terminus of ER specifically reverted the E2-repressed transcriptional program into E2-activated one. We further demonstrated that RNAs transcribed from these E2-repressed enhancers (eRNAs) act as the exterior determinants of ER activity in gene repression. In addition to stabilizing promoter-enhancer looping structure, these eRNAs recruit ER to particular chromatin loci, and facilitate the hierarchical formation of a functional complex responsible for transcriptional repression. Thus, our findings suggest that by targeting distinct functional domains of ER, we may be able to reprogram expression of a specific subset of ER targets, which play critical roles in conferring malignant phenotypes of breast cancer cells. Meanwhile, as a distinctive class of cis-acting elements besides chromatin regulatory regions, eRNAs help to refine ER-dependent transcriptional program that contributes to the development and progression of breast cancer. Citation Format: Mei Yang, Zhao Zhang, Kexin Xu. Segregating activities of the estrogen receptor in gene regulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5203.

Sex-dimorphic estrogen receptor regulation of ventromedial hypothalamic nucleus glucoregulatory neuron adrenergic receptor expression in hypoglycemic male and female rats

The ventromedial hypothalamic nucleus (VMN) is a vital component of the neural circuitry that regulates glucostasis. Norepinephrine (NE) controls VMN gluco-inhibitory γ-aminobutyric acid (GABA) and gluco-stimulatory nitric oxide (NO) transmission. Sex-specific insulin-induced hypoglycemic (IIH) patterns of VMN GABA signaling are estrogen receptor-alpha (ERα)- and -beta (ERβ)-dependent. Current research utilized combinatory immunocytochemistry, laser-microdissection, and Western blot techniques in a pharmacological approach to address the hypothesis that ERα and/or -β mediate sex-dimorphic VMN GABAergic and/or nitrergic nerve cell receptivity to NE and estradiol during IIH. The impact of these ER on expression of the pyruvate recycling pathway marker proteins glutaminase (GLS) and malic enzyme-1 (ME-1) was also examined. Both VMN neuron populations express ERα, ERβ, and G protein-coupled estrogen receptor-1 (GPER), along with alpha1, alpha2, and beta1 adrenergic receptor (AR) proteins. NO neurons exhibited ERα/β-dependent (beta1 AR, GPER) and -independent (alpha1 AR) sex differences in receptor protein responses to hypoglycemia. Similarly, sex-dimorphic effects of IIH on alpha1 AR, alpha2 AR, and ERα profiles in GABA neurons involve ERα/β. These ERs also underlie divergent adjustments in gluco-regulatory nerve cell GLS and ME-1 protein expression in hypoglycemic males and females. Sex-specific nitrergic and GABAergic nerve cell sensitivity to NE and E, respectively, during IIH may contribute to sex-contingent patterns of neurotransmitter signaling.

Neddylation Inactivation Facilitates FOXO3a Nuclear Export to Suppress Estrogen Receptor Transcription and Improve Fulvestrant Sensitivity.

How the neddylation pathway functions in breast tumor and regulation of estrogen receptor (ER) expression is rarely reported. The purpose of this study was to identify the role of neddylation in breast cancer and ER expression, and further explore the underlying mechanisms. Expression patterns of nedd8-activating enzyme (NAE) and nedd8, two key proteins in the neddylation pathway, were examined in human breast specimens. ER-α expression was investigated using animal 18F-FES-PET/CT and immunoblotting upon NAE inhibitor MLN4924 treatment. Chromatin immunoprecipitation assay, luciferase reporter promoter assay, and the CRISPR-Cas9 system were used to elucidate the mechanism of ER-α regulation by MLN4924. The ER-positive breast cancer mouse model was used to determine the synergetic effect of MLN4924 and fulvestrant on tumor growth. All statistical tests were two-sided. Both NAE1 and nedd8 expressions were higher in the ER-positive subgroup. Higher expressions of NAE1 and nedd8 indicated poorer prognosis. Importantly, ER-α expression was significantly downregulated upon MLN4924 treatment in vitro and in vivo. Mechanistically, MLN4924 treatment delayed serum and glucocorticoid-induced protein kinase (SGK) degradation and induced Forkhead box O3a (FOXO3a) nuclear export as well as decreased binding to the ESR1 promoter. Importantly, MLN4924 single or synergized with fulvestrant significantly suppressed the growth of ER-positive breast cancer in vitro and in vivo. Our proof-of-principle study determines the activation of neddylation in breast tumor tissues for the first time and reveals a new ER-α regulatory mechanism, as well as further explores an effective approach to improve fulvestrant sensitivity through a neddylation inactivation combination.

Hypoxia differentially regulates estrogen receptor alpha in 2D and 3D culture formats

Hypoxia is a common feature in solid tumors. Clinical samples show a positive correlation between the expression of the hypoxia-inducible factor HIF-1α and estrogen receptor alpha (ERα) and a negative correlation between HIF-1α and hormone sensitivity. Results from monolayer cultures are in contention with clinical observations, showing that ER (+) cell lines no longer express ERα under hypoxic conditions (1% O2). Here, we compared the impact of hypoxia on the ERα signaling pathway for T47D cells in a 2D and 3D culture format. In the 2D format, the cells were cultured as monolayers. In the 3D format, paper-based scaffolds supported cells suspended in a collagen matrix. Using ELISA, Western blot, and immunofluorescence measurements, we show that hypoxia differentially regulates ERα protein levels in a culture environment-dependent manner. In the 2D format, the protein levels are significantly decreased in hypoxia. In the 3D format, the protein levels are maintained in hypoxia. Hypoxia reduced ERα transcriptional activation in both culture formats. These results highlight the importance of considering tissue dimensionality for in vitro studies. They also show that ERα protein levels in hypoxia are not an accurate indicator of ERα transcriptional activity, and confirm that a positive stain for ERα in a clinical sample may not necessarily indicate hormone sensitivity.

The Role of 17β-Estradiol and Estrogen Receptors in Regulation of Ca2+ Channels and Mitochondrial Function in Cardiomyocytes.

Numerous epidemiological, clinical, and animal studies showed that cardiac function and manifestation of cardiovascular diseases (CVDs) are different between males and females. The underlying reasons for these sex differences are definitely multifactorial, but major evidence points to a causal role of the sex steroid hormone 17β-estradiol (E2) and its receptors (ER) in the physiology and pathophysiology of the heart. Interestingly, it has been shown that cardiac calcium (Ca2+) ion channels and mitochondrial function are regulated in a sex-specific manner. Accurate mitochondrial function and Ca2+ signaling are of utmost importance for adequate heart function and crucial to maintaining the cardiovascular health. Due to the highly sensitive nature of these processes in the heart, this review article highlights the current knowledge regarding sex dimorphisms in the heart implicating the importance of E2 and ERs in the regulation of cardiac mitochondrial function and Ca2+ ion channels, thus the contractility. In particular, we provide an overview of in-vitro and in-vivo studies using either E2 deficiency; ER deficiency or selective ER activation, which suggest that E2 and ERs are strongly involved in these processes. In this context, this review also discusses the divergent E2-responses resulting from the activation of different ER subtypes in these processes. Detailed understanding of the E2 and ER-mediated molecular and cellular mechanisms in the heart under physiological and pathological conditions may help to design more specifically targeted drugs for the management of CVDs in men and women.

Hindbrain estrogen receptor regulation of ventromedial hypothalamic glycogen metabolism and glucoregulatory transmitter expression in the hypoglycemic male rat

Estrogen receptor-alpha (ERα) and -beta (ERβ) occur in key elements of the brain gluco-homeostatic network in both sexes, including the hindbrain dorsal vagal complex (DVC), but the influence of distinct receptor populations on this critical function is unclear. The ventromedial hypothalamic nucleus (VMN) maintains glucose balance by integrating nutrient, endocrine, and neurochemical cues, including metabolic sensory information supplied by DVC A2 noradrenergic neurons. Current research utilized the selective ERα and ERβ antagonists MPP and PHTPP to characterize effects of DVC ERs on VMN norepinephrine (NE) activity and metabolic neurotransmitter signaling in insulin-induced hypoglycemic (IIH) male rats. Data show that ERβ inhibits VMN glycogen synthase and stimulates phosphorylase protein expression, while attenuating hypoglycemic augmentation of glycogen content. Furthermore, both ERs attenuate VMN glucose concentrations during IIH. Hypoglycemic up-regulation of nitric oxide (NO) and brain-derived neurotrophic factor (BDNF) signaling was correspondingly driven by ERα or -β, whereas GABA and steroidogenic factor-1 were respectively suppressed independently of ER input or by ERβ. IIH intensified VMN NE accumulation by ERβ-dependent mechanisms, but did not alter NE levels in other gluco-regulatory loci. ERβ amplified the magnitude of insulin-induced decline in blood glucose. Both ERs regulate corticosterone, but not glucagon secretion during IIH and oppose hypoglycemic diminution of circulating free fatty acids. These findings identify distinguishing versus common VMN functions targeted by DVC ERα and -β. Sex differences in hypoglycemic VMN NE accumulation, glycogen metabolism, and transmitter signaling may involve, in part, discrepant regulatory involvement or differential magnitude of impact of these hindbrain ERs.

Hormonal Regulation of Estrogen Receptors

BackgroundWe previously showed that estrogen has beneficial effects on cardiovascular function via the novel G‐protein coupled estrogen receptor (GPER). Selectively activating GPER may elicit beneficial cardiovascular effects of estrogen without eliciting deleterious effects. Receptor expression is important in developing targeted pharmacological therapies, but the regulation and expression of estrogen receptors is still not fully understood.ObjectiveOur goal was to study the effects androgens, glucocorticoids, and progesterone on the expression of the classical estrogen receptor ERα and novel estrogen receptor GPER.MethodsMouse aortic smooth muscle cells (MOVAS) were grown in 10% FBS media to 80% confluency and then starved for 24 h in charcoal‐stripped 0.5% FBS. The plates were treated for 24 h with 100 nm of dexamethasone (DEX), dihydrotestosterone (DHT), medroxyprogesterone acetate (MPA), or vehicle. After treatment, RNA was extracted and droplet digital PCR was used to quantify the expression of both GPER and ERα. Results were analyzed using a one‐way ANOVA.ResultsGPER expression was decreased by both DHT (66% of control, p=0.006, n=9) and MPA (70% of control, p=0.012, n=6). The impact of DEX on GPER was not statistically significant (89% of control, p=0.245, n=9). ERα expression was significantly reduced by DEX (65% of control, p=0.0046, n=9), DHT (56% of control, p=0.004, n=9), and MPA (52% of control, p=0.005, n=6) as compared to controls.ConclusionsIn cultured vascular smooth muscle cells, DHT and MPA decreased the expression GPER, while DEX, DHT, and MPA downregulated ERα. These results suggest that androgens, glucocorticoids, and progesterone act at the transcriptional level to decrease the expression of GPER and ERα. This decrease in receptor expression could lessen beneficial effects of GPER and/or ERα on cardiovascular function. Future studies will address the impact of androgens, glucocorticoids, and progesterone on the molecular mechanisms and in vivo cardiovascular responses to estrogen. The regulation of estrogen receptor expression is important for understanding the clinical interactions that may alter the response to hormone therapy.Support or Funding InformationFunding was provided by NIH HL133619 to SHL.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

PI3K Inhibition Activates SGK1 via a Feedback Loop to Promote Chromatin-Based Regulation of ER-Dependent Gene Expression

The PI3K pathway integrates extracellular stimuli to phosphorylate effectors such as AKT and serum-and-glucocorticoid-regulated kinase (SGK1). We have previously reported that the PI3K pathway regulates estrogen receptor (ER)-dependent transcription in breast cancer through the phosphorylation of the lysine methyltransferase KMT2D by AKT. Here, we show that PI3Kα inhibition, via a negative-feedback loop, activates SGK1 to promote chromatin-based regulation of ER-dependent transcription. PI3K/AKT inhibitors activate ER, which promotes SGK1 transcription through direct binding to its promoter. Elevated SGK1, in turn, phosphorylates KMT2D, suppressing its function, leading to a loss of methylation of lysine 4 on histone H3 (H3K4) and a repressive chromatin state at ER loci to attenuate ER activity. Thus, SGK1 regulates the chromatin landscape and ER-dependent transcription via the direct phosphorylation of KMT2D. These findings reveal an ER-SGK1-KMT2D signaling circuit aimed to attenuate ER response through a role for SGK1to program chromatin and ER transcriptional output.

A Novel Micro RNA Feedback Loop of High Mobility Group Protein A1a in Regulating Estrogen Receptor Alpha Alternative Splicing

The hERI± gene is known for its major role in estrogen dependent growth of breast cancer. ERI± positivity is a hallmark in treating these cancers. Though there are many isoforms reported for hERI±, the splicing regulation...

PA28\u03b1\u03b2 overexpression enhances learning and memory of female mice without inducing 20S proteasome activity

BackgroundThe proteasome system plays an important role in synaptic plasticity. Induction and maintenance of long term potentiation is directly dependent on selective targeting of proteins for proteasomal degradation. The 20S proteasome activator PA28αβ activates hydrolysis of small nonubiquitinated peptides and possesses protective functions upon oxidative stress and proteinopathy. The effect of PA28αβ activity on behavior and memory function is, however, not known. We generated a mouse model that overexpresses PA28α (PA28αOE) to understand PA28αβ function during healthy adult homeostasis via assessment of physiological and behavioral profiles, focusing on female mice.ResultsPA28α and PA28β protein levels were markedly increased in all PA28αOE tissues analyzed. PA28αOE displayed reduced depressive-like behavior in the forced swim test and improved memory/learning function assessed by intersession habituation in activity box and shuttle box passive avoidance test, with no significant differences in anxiety or general locomotor activity. Nor were there any differences found when compared to WT for body composition or immuno-profile. The cognitive effects of PA28αOE were female specific, but could not be explained by alterations in estrogen serum levels or hippocampal regulation of estrogen receptor β. Further, there were no differences in hippocampal protein expression of neuronal or synaptic markers between PA28αOE and WT. Biochemical analysis of hippocampal extracts demonstrated that PA28α overexpression did not increase PA28–20S peptidase activity or decrease K48-polyubiquitin levels. Instead, PA28αOE exhibited elevated efficiency in preventing aggregation in the hippocampus.ConclusionsThis study reveals, for the first time, a connection between PA28αβ and neuronal function. We found that PA28α overexpressing female mice displayed reduced depressive-like behavior and enhanced learning and memory. Since the positive effects of PA28α overexpression arose without an activation of 20S proteasome capacity, they are likely independent of PA28αβ’s role as a 20S proteasome activator and instead depend on a recognized chaperone-like function. These findings suggest that proteostasis in synaptic plasticity is more diverse than previously reported, and demonstrates a novel function of PA28αβ in the brain.