Estrogen receptor subcellular localization and cardiometabolism

Mitogen-Activated Protein Kinase Phosphatase-2 Deletion Promotes Hyperglycemia and Susceptibility to Streptozotocin-Induced Diabetes in Female Mice In Vivo

The development of type 2 diabetes (T2D) is largely dependent on the maintenance of pancreatic islet function and mass. Sexual dimorphism in T2D is evident in many areas, such as pathophysiology, treatment, and prevention. Mitogen-activated protein kinase phosphatase-2 (MKP-2) has a distinct role in the regulation of cell proliferation and the development of metabolic disorders. However, whether there is a causal relationship between MKP-2 and diabetes onset is unclear. The aim of this study was to determine the role of MKP-2 in the regulation of whole-body glucose homeostasis and the impact on pancreatic islet function using streptozotocin-induced pancreatic injury. Here, we show that female mice with whole-body deletion of MKP-2 exhibit hyperglycemia in mouse models treated with multiple low doses of streptozotocin (STZ). In comparison, both male MKP-2 wild-type and knockout mice were hyperglycemic. Consistent with the hyperglycemia, female MKP-2-deficient mice exhibited reduced islet size. Under T2D conditions, MKP-2-deficient mice display enhanced pancreatic JNK and ERK phosphorylation that is associated with the downregulation of genes important for pancreatic islet development and function, Pdx-1 and MafA. Furthermore, we found impaired metabolic flux in adipose tissue that is consistent with hyperglycemia and dysfunctional pancreas. MKP-2 deletion results in reduced Akt activation that is associated with increased adiposity and insulin resistance in female MKP-2 KO mice. These studies demonstrate the critical role of MKP-2 in the development of T2D diabetes in vivo. This suggests that MKP-2 may have a gender-specific role in diabetes development. This discovery raises the possibility that postmenopausal prevention of T2D may benefit from the activation of MKP-2 activity in islet cells.

New Approach Methodologies (NAMs) to assess killer whale (Orcinus orca) estrogen receptor alpha (ERα) transactivation potencies by DDTs and their risks

Killer whales (Orcinus orca), as apex predators, accumulate high levels of persistent organic pollutants (POPs) such as dichlorodiphenyltrichloroethane and its analogs (DDTs) and face their risks at the population level. The assessment of the function of estrogen receptor alpha (ERα) is crucial for evaluating impact of DDTs on killer whale endocrine and reproductive health. However, due to ethical constraints, little is known about the effects of DDTs on the function of killer whale ERα (kwERα). This study aimed to assess kwERα transactivation potencies in response to various DDTs (p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD, p,p'-DDE, o,p'-DDE, and p,p'-DDOH) by New Approach Methodologies (NAMs). We constructed an in vitro kwERα-expressed reporter gene assay and measured transactivation potencies of DDTs as the 10 % effective concentration (REC10) relative to the maximum response to 17β-estradiol exposure. We also employed in silico approaches such as molecular docking and protein-ligand network analysis (PLNA) to elucidate the interaction of kwERα protein and DDTs. The in vitro results revealed an estrogenic potency in the order of 17β-estradiol > o,p'-DDT > o,p'-DDE > o,p'-DDD > p,p'-DDD > p,p'-DDOH > p,p'-DDT > p,p'-DDE (no activity). Strong positive correlations were found between in vitro REC10 values and in silico docking scores, suggesting the structure-activity relationship of the estrogenic potencies of DDTs to kwERɑ. PLNA highlighted contribution of Glu353 and Phe404 in kwERα as essential residues to the interaction with DDTs. Risk assessments indicated that the o,p'-DDT-estrogenic equivalency quantities of DDTs in the blubber of both Irish and Canadian Arctic killer whales exceeded the in vitro REC10 of o,p'-DDT, suggesting a significant risk of kwERα-mediated endocrine disruption in these populations. These findings underscore the importance of NAMs including in vitro and in silico approaches for assessing the endocrine and reproductive risk in killer whales.

Capsaicin (But Not Other Vanillins) Enhances Estrogen Binding to Its Receptor: Implications for Power Sports and Cancers

Capsaicin (CAP), the pain-inducing compound in chili peppers, exerts its effects mainly through the transient receptor potential vanilloid channel 1 (TRPV1), which mediates pain perception and some metabolic functions. CAP has also been demonstrated to improve performance in power sports (but not endurance sports) and does so mainly for females. CAP may also have anti-cancer effects. Many mechanisms have been explored to explain these phenomena, particularly the effects of TRPV1 activation for calcium influx, glucose transporter (GLUT) upregulation and inhibition of insulin (INS) production, but two important ones seem to have been missed. We demonstrate here that CAP binds to both INS and to the estrogen receptor (ESR1), enhancing estradiol binding. Other TRPV1 agonists, such as vanillin, vanillic acid and acetaminophen, have either no effect or inhibit estrogen binding. Notably, TRPV1, ESR1 and INS share significant regions of homology that may aid in identifying the CAP-binding site on the ESR1. Because activation of the estrogen receptor upregulates GLUT expression and thereby glucose transport, we propose that the observed enhancement of performance in power sports, particularly among women, may result, in part, from CAP enhancement of ESR1 function and prevent INS degradation. Chronic exposure to CAP, however, may result in downregulation and internalization of ESR1, as well as TRPV1 stimulation of glucagon-like peptide 1 (GLP-1) expression, both of which downregulate GLUT expression, thereby starving cancer cells of glucose. The binding of capsaicin to the ESR1 may also enhance ESR1 antagonists such as tamoxifen, benefiting some cancer patients.

Loss of ERα involved-HER2 induction mediated by the FOXO3a signaling pathway in fulvestrant-resistant breast cancer

Patients with estrogen receptor alpha (ERα)-positive breast cancer are commonly treated with anti-estrogen drugs as an initial treatment strategy. Fulvestrant, an estrogen receptor antagonist, effectively blocks ERα signaling; however, long-term fulvestrant treatment induces drug resistance in the absence of ERα. In this study, we investigated the molecular mechanism underlying the loss of ERα, FOXO3a, and induction of HER2 in fulvestrant-resistant breast cancer. Short-term fulvestrant treatment degraded ERα proteins via the ubiquitin-proteasome degradation pathway in MCF7 cells. MCF7 cells turn into highly proliferative cells (fulvestrant-resistant cells: Ful-R) after long-term fulvestrant treatment. These cells exhibit markedly suppressed estrogen and progesterone receptor levels. The phosphorylation of EGFR, HER2, and ERK was induced in Ful-R, and these phosphorylation inhibitors suppressed cell proliferation in Ful-R. FOXO3a, a transcriptional regulator of ERα was decreased in Ful-R, and a ubiquitin-proteasome inhibitor restored the expression of FOXO3a. These results suggest that the suppression of FOXO3a and ERα led to the increased expression of TGF-α, EGFR, and HER2 and subsequent cell proliferation in Ful-R. This study highlights the potential development of therapeutic drugs targeting FOXO3a for the treatment of HER2-positive, estrogen, and progesterone receptor-negative her2-type proliferative breast cancers.

The role of estrogen receptors in intracellular estrogen signaling pathways, an overview

To date five members of estrogen receptors (ESRs) have been reported. They are grouped into two classes, the nuclear estrogen receptors are members of the nuclear receptor family which found at nuclear, cytoplasm and plasma membrane, and the membrane estrogen receptors, such as G protein-coupled estrogen receptor 1, ESR-X and Gq-coupled membrane estrogen receptor. The structure and function of estrogen receptors, and interaction between ESR and coregulators were reviewed. In canonical pathway ESRs can translocate to the nucleus, bind to the target gene promotor with or without estrogen responsive element and regulate transcription, mediating the genomic effects of estrogen. Coactivators and corepressors are recruited to activate or inhibit transcription by activated ESRs. Many coactivators and corepressors are recruited to activate or inhibit ESR mediated gene transcription via different mechanisms. ESRs also indirectly bind to the promoter via interaction with other transcription factors, tethering the transcription factors. ESRs can be phosphorylated by several kinases such as p38, extracellular-signal-regulated kinase, and activated protein kinase B, and which activates transcription without ligand binding. Non-genomic estrogen action can be manifested by the increases of cytoplasmic NO and Ca2+ through the activation of membrane ESRs. In female, ESRs signaling is crucial for folliculogenesis, oocyte growth, ovulation, oviduct and uterus. In male, ESRs signaling modulates libido, erectile function, leydig cell steroidogenesis, sertoli cell's function, and epididymal fluid homeostatsis, supporting spermatogenesis and sperm maturation. The abnormal ESRs signaling is believed to be closely related to reproductive diseases and cancer.

Sex-Based Mechanisms of Cardiac Development and Function: Applications for Induced-Pluripotent Stem Cell Derived-Cardiomyocytes

Males and females exhibit intrinsic differences in the structure and function of the heart, while the prevalence and severity of cardiovascular disease vary in the two sexes. However, the mechanisms of this sex-based dimorphism are yet to be elucidated. Sex chromosomes and sex hormones are the main contributors to sex-based differences in cardiac physiology and pathophysiology. In recent years, the advances in induced pluripotent stem cell-derived cardiac models and multi-omic approaches have enabled a more comprehensive understanding of the sex-specific differences in the human heart. Here, we provide an overview of the roles of these two factors throughout cardiac development and explore the sex hormone signaling pathways involved. We will also discuss how the employment of stem cell-based cardiac models and single-cell RNA sequencing help us further investigate sex differences in healthy and diseased hearts.

Analyses of hypoxia-related risk factors and clinical relevance in breast cancer

Introduction

Hypoxia plays an important role in the heterogeneity, relapse, metastasis, and drug resistance of breast cancer. In this study, we explored the hypoxia-related biological signatures in different subtypes of breast cancer and identified the key prognostic factors by bioinformatics methods.

Methods

Based on The Cancer Genome Atlas (TCGA) Breast Cancer datasets, we divided the samples into immune-activated/suppressed populations by single-sample gene set enrichment analysis (ssGSEA) and then used hierarchical clustering to further identify hypoxic/non-hypoxic populations from the immune-suppressed samples. A hypoxia related risk model of breast cancer was constructed.

Results

Nuclear factor interleukin-3 regulated (NFIL3), serpin family E member 1 (SERPINE1), FOS, biglycan (BGN), epidermal growth factor receptor (EGFR), and sushi-repeat-containing protein, X-linked (SRPX) were identified as key hypoxia-related genes. Margin status, American Joint Committee on Cancer (AJCC) stage, hypoxia status, estrogen receptor/progesterone receptor (ER/PR) status, NFIL3, SERPINE1, EGFR, and risk score were identified as independent prognostic indicators for breast cancer patients. The 3- and 5-year survival curves of the model and immunohistochemical staining on the breast cancer microarray verified the statistical significance and feasibility of our model. Among the different molecular types of breast cancer, ER/PR+ and HER2+ patients might have higher hypoxia-related risk scores. ER/PR-negative samples demonstrated more activated immune-related pathways and better response to most anticancer agents.

Discussion

Our study revealed a novel risk model and potential feasible prognostic factors for breast cancer and might provide new perspectives for individual breast cancer treatment.

Deubiquitinase UCHL1 regulates estradiol synthesis by stabilizing voltage-dependent anion channel 2

Lack of estradiol production by granulosa cells blocks follicle development, causes failure of estrous initiation, and results in an inability to ovulate. The ubiquitin-proteasome system plays a critical role in maintaining protein homeostasis and stability of the estrous cycle, but knowledge of deubiquitination enzyme function in estradiol synthesis is limited. Here, we observe that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) is more significant in estrous sows and high litter-size sows than in nonestrous sows and low-yielding sows. Overexpression of UCHL1 promotes estradiol synthesis in granulosa cells, and interference with UCHL1 has the opposite effect. UCHL1 binds, deubiquitinates, and stabilizes voltage-dependent anion channel 2 (VDAC2), promoting the synthesis of the estradiol precursor pregnenolone. Cysteine 90 (C90) of UCHL1 is necessary for its deubiquitination activity, and Lys45 and Lys64 in VDAC2 are essential for its ubiquitination and degradation. In vivo, compared with WT and sh-NC-AAV groups, the estrus cycle of female mice is disturbed, estradiol level is decreased, and the number of antral follicles is decreased after the injection of sh-UCHL1-AAV into ovarian tissue. These findings suggest that UCHL1 promotes estradiol synthesis by stabilizing VDAC2 and identify UCHL1 as a candidate gene affecting reproductive performance.

URAT1 is expressed in cardiomyocytes and dotinurad attenuates the development of diet-induced metabolic heart disease

We recently reported that the selective inhibition of urate transporter-1 (URAT1), which is primarily expressed in the kidneys, ameliorates insulin resistance by attenuating hepatic steatosis and improving brown adipose tissue function in diet-induced obesity. In this study, we evaluated the effects of dotinurad, a URAT1-selective inhibitor, on the hearts of high-fat diet (HFD)-fed obese mice for 16-20 weeks and on neonatal rat cardiomyocytes (NRCMs) exposed to palmitic acid. Outside the kidneys, URAT1 was also expressed in cardiomyocytes and indeed worked as a uric acid transporter. Dotinurad substantially attenuated HFD-induced cardiac fibrosis, inflammatory responses, and cardiac dysfunction. Intriguingly, among various factors related to the pathophysiology of diet-induced obesity, palmitic acid significantly increased URAT1 expression in NRCMs and subsequently induced apoptosis, oxidative stress, and inflammatory responses via MAPK pathway, all of which were reduced by dotinurad. These results indicate that URAT1 is a potential therapeutic target for metabolic heart disease.

CETP expression ameliorates endothelial function in female mice through estrogen receptor-α and endothelial nitric oxide synthase pathway

Endothelial dysfunction is an early manifestation of atherosclerosis. The cholesteryl ester transfer protein (CETP) has been considered proatherogenic by reducing plasma HDL levels. However, CETP may exhibit cell- or tissue-specific effects. We have previously reported that male mice expressing the human CETP gene show impaired endothelium-mediated vascular relaxation associated with oxidative stress. Although sexual dimorphisms on the metabolic role of CETP have been proposed, possible sex differences in the vascular effects of CETP were not previously studied. Thus, here we investigated the endothelial function of female CETP transgenic mice as compared with nontransgenic controls (NTg). Aortas from CETP females presented preserved endothelium-dependent relaxation to acetylcholine and an endothelium-dependent reduction of phenylephrine-induced contraction. eNOS phosphorylation (Ser1177) and calcium-induced NO levels were enhanced, whereas reactive oxygen species (ROS) production and NOX2 and SOD2 expression were reduced in the CETP female aortas. Furthermore, CETP females exhibited increased aortic relaxation to 17β-estradiol (E2) and upregulation of heat shock protein 90 (HSP90) and caveolin-1, proteins that stabilize estrogen receptor (ER) in the caveolae. Indeed, CETP females showed an increased E2-induced relaxation in a manner sensitive to estrogen receptor-α (ERα) and HSP90 inhibitors methylpiperidinopyrazole (MPP) and geldanamycin, respectively. MPP also impaired the relaxation response to acetylcholine in CETP but not in NTg females. Altogether, the study indicates that CETP expression ameliorates the anticontractile endothelial effect and relaxation to E2 in females. This was associated with less ROS production, and increased eNOS-NO and E2-ERα pathways. These results highlight the need for considering the sex-specific effects of CETP on cardiovascular risk.NEW & NOTEWORTHY Here we demonstrated that CETP expression has a sex-specific impact on the endothelium function. Contrary to what was described for males, CETP-expressing females present preserved endothelium-dependent relaxation to acetylcholine and improved relaxation response to 17β-estradiol. This was associated with less ROS production, increased eNOS-derived NO, and increased expression of proteins that stabilize estrogen receptor-α (ERα), thus increasing E2-ERα signaling sensitivity. These results highlight the need for considering the sex-specific effects of CETP on cardiovascular risk.

Membrane estrogen receptor-α contributes to female protection against high-fat diet-induced metabolic disorders

Background

Estrogen Receptor α (ERα) is a significant modulator of energy balance and lipid/glucose metabolisms. Beyond the classical nuclear actions of the receptor, rapid activation of intracellular signaling pathways is mediated by a sub-fraction of ERα localized to the plasma membrane, known as Membrane Initiated Steroid Signaling (MISS). However, whether membrane ERα is involved in the protective metabolic actions of endogenous estrogens in conditions of nutritional challenge, and thus contributes to sex differences in the susceptibility to metabolic diseases, remains to be clarified.

Methods

Male and female C451A-ERα mice, harboring a point mutation which results in the abolition of membrane localization and MISS-related effects of the receptor, and their wild-type littermates (WT-ERα) were maintained on a normal chow diet (NCD) or fed a high-fat diet (HFD). Body weight gain, body composition and glucose tolerance were monitored. Insulin sensitivity and energy balance regulation were further investigated in HFD-fed female mice.

Results

C451A-ERα genotype had no influence on body weight gain, adipose tissue accumulation and glucose tolerance in NCD-fed mice of both sexes followed up to 7 months of age, nor male mice fed a HFD for 12 weeks. In contrast, compared to WT-ERα littermates, HFD-fed C451A-ERα female mice exhibited: 1) accelerated fat mass accumulation, liver steatosis and impaired glucose tolerance; 2) whole-body insulin resistance, assessed by hyperinsulinemic-euglycemic clamps, and altered insulin-induced signaling in skeletal muscle and liver; 3) significant decrease in energy expenditure associated with histological and functional abnormalities of brown adipose tissue and a defect in thermogenesis regulation in response to cold exposure.

Conclusion

Besides the well-characterized role of ERα nuclear actions, membrane-initiated ERα extra-nuclear signaling contributes to female, but not to male, protection against HFD-induced obesity and associated metabolic disorders in mouse.

Hormonal regulation of metabolism-recent lessons learned from insulin and estrogen

Hormonal signaling plays key roles in tissue and metabolic homeostasis. Accumulated evidence has revealed a great deal of insulin and estrogen signaling pathways and their interplays in the regulation of mitochondrial, cellular remodeling, and macronutrient metabolism. Insulin signaling regulates nutrient and mitochondrial metabolism by targeting the IRS-PI3K-Akt-FoxOs signaling cascade and PGC1α. Estrogen signaling fine-tunes protein turnover and mitochondrial metabolism through its receptors (ERα, ERβ, and GPER). Insulin and estrogen signaling converge on Sirt1, mTOR, and PI3K in the joint regulation of autophagy and mitochondrial metabolism. Dysregulated insulin and estrogen signaling lead to metabolic diseases. This article reviews the up-to-date evidence that depicts the pathways of insulin signaling and estrogen-ER signaling in the regulation of metabolism. In addition, we discuss the cross-talk between estrogen signaling and insulin signaling via Sirt1, mTOR, and PI3K, as well as new therapeutic options such as agonists of GLP1 receptor, GIP receptor, and β3-AR. Mapping the molecular pathways of insulin signaling, estrogen signaling, and their interplays advances our understanding of metabolism and discovery of new therapeutic options for metabolic disorders.

An Extended DNA Binding Domain of the Estrogen Receptor Alpha Directly Interacts with RNAs in Vitro

Estrogen receptor alpha (ERα) is a ligand-responsive transcription factor critical for sex determination and development. Recent reports challenge the canonical view of ERα function by suggesting an activity beyond binding dsDNA at estrogen-responsive promotor elements: association with RNAs in vivo. Whether these interactions are direct or indirect remains unknown, which limits the ability to understand the extent, specificity, and biological role of ERα-RNA binding. Here we demonstrate that an extended DNA-binding domain of ERα directly binds a wide range of RNAs in vitro with structural specificity. ERα binds RNAs that adopt a range of hairpin-derived structures independent of sequence, while interacting poorly with single- and double-stranded RNA. RNA affinities are only 4-fold weaker than consensus dsDNA and significantly tighter than nonconsensus dsDNA sequences. Moreover, RNA binding is competitive with DNA binding. Together, these data show that ERα utilizes an extended DNA-binding domain to achieve a high-affinity/low-specificity mode for interacting with RNA.

Bortezomib-Encapsulated Dual Responsive Copolymeric Nanoparticles for Gallbladder Cancer Targeted Therapy

Gallbladder cancer (GBC) is a rare but the most malignant type of biliary tract tumor. It is usually diagnosed at an advanced stage and conventional treatments are unsatisfactory. As a proteasome inhibitor, bortezomib (BTZ) exhibits excellent antitumor ability in GBC. However, the long-term treatment efficacy is limited by its resistance, poor stability, and high toxicity. Herein, BTZ-encapsulated pH-responsive copolymeric nanoparticles with estrone (ES-NP_{(BTZ; Ce6)} ) for GBC-specific targeted therapy is reported. Due to the high estrogen receptor expression in GBC, ES-NP_{(BTZ; Ce6)} can rapidly enter the cells and accumulate near the nucleus via ES-mediated endocytosis. Under acidic tumor microenvironment (TME) and 808 nm laser irradiation, BTZ is released and ROS is generated by Ce6 to destroy the "bounce-back" response pathway proteins, such as DDI2 and p97, which can effectively inhibit proteasomes and increase apoptosis. Compared to the traditional treatment using BTZ monotherapy, ES-NP_{(BTZ; Ce6)} can significantly impede disease progression at lower BTZ concentrations and improve its resistance. Moreover, ES-NP_{(BTZ; Ce6)} demonstrates similar antitumor abilities in patient-derived xenograft animal models and five other types of solid tumor cells, revealing its potential as a broad-spectrum antitumor formulation.

Antibody Validation for Estrogen Receptor Beta

Antibodies can cross-react with proteins other than their intended targets, and antibody-based applications can, if not properly validated, lead to flawed interpretations. When evaluating 13 anti-estrogen receptor beta (ERβ) antibodies in 2017, we concluded that only one of them was specific. Applying this antibody in immunohistochemistry of over 44 different normal human tissues and 20 types of cancers revealed ERβ expression in only a few selected tissues. This aligned with mRNA evidence but contradicted a large set of published literature. ERβ protein expression continues to be reported in tissues without clear support by mRNA expression. In this chapter, we describe how ERβ antibodies can be thoroughly validated and discuss selection of well-characterized positive and negative controls. The validation scheme presented is applicable for immunohistochemistry and Western blotting. The protocol includes evaluation of mRNA evidence, use of public databases, assessment of on- and off-target binding, and an optional step for corroboration with immunoprecipitation and mass spectrometry.

Prognostic Significance of Estrogen Receptor Alpha in Oral Squamous Cell Carcinoma

Simple Summary

Although the survival rate has improved over the past decades, the prognosis of oral squamous cell carcinoma (OSCC) is still poor, and new treatment strategies are required. The aim of this study was to evaluate estrogen receptor alpha (ERα) expression in OSCC in a large patient cohort as a potential prognostic marker and therapeutic target. The findings indicated a rare expression of ERα that, however, was associated with a dramatic decrease of overall survival in male patients. In ERα-positive OSCC patients, an ER-based therapeutic (adjuvant) approach in the future might be conceivable based on the findings of this study.

Abstract

Introduction: Several studies suggest an estrogen receptor alpha (ERα)-mediated influence on the pathogenesis of oral squamous cell carcinoma (OSCC), as described for other malignancies that are not considered to be primarily hormone-dependent. Recently, an association between ERα expression and improved survival in oropharyngeal squamous cell carcinoma (OPSCC) has been found. However, the prognostic relevance of ERα in OSCC has not been proven to date. Therefore, the aim of this study was to evaluate ERα expression in OSCC in a large patient cohort and analyze its influence on survival and recurrence. Material and Methods: A total of 316 patients with primary OSCC who received initial surgical therapy were included in this analysis. The expression of ERα was evaluated on tissue microarrays by immunohistochemistry in the primary tumor and/or primary lymph node metastases. The expression level was quantified by light microscopy using the immunoreactive score (IRS) for estrogen receptor detection. An IRS equal to or greater than 2 was considered positive. The 5-year overall survival (OS) and relapse-free survival (RFS) were examined by the Kaplan–Meier method and log-rank test. Results: A total of 316 patients (111 females; 205 males) with a mean age of 61.3 years (range 27–96 years) were included in this study. In 16 patients (5.1%; 6 females and 10 males), positive ERα expression was found in the primary tumor (n = 11; 11/302) or lymph node metastases (n = 5; 5/52). Patients with positive ERα expression in primary tumors/primary lymph node metastases had a significantly lower OS and RFS (p = 0.012; p = 0.0053) compared to ERα-negative patients. Sub-group analysis in relation to gender revealed a highly significant influence of ERα expression on OS and RFS in males but not in females, both for the ERα-positive primary tumor cohort (males: p = 0.0013; p < 0.0001; females: p = 0.56; p = 0.89) and the ERα-positive primary tumor/primary lymph node metastasis cohort (males: p < 0.0001; p < 0.0001; females: p = 0.95; p = 0.96). In multivariate cox regression analysis, the ERα IRS of primary tumors (dichotomized; ERα+ vs. ERα−) was an independent risk factor for OS (HR = 4.230; 95%CI 1.616–11.076; p = 0.003) and RFS (HR = 12.390; 95%CI 4.073–37.693; p < 0.001) in the male cohort. There was a significant difference (p = 0.006) of ERα positivity with regard to the localization of the primary tumor. ERα positivity in the primary tumor was significantly associated (p = 0.026) with UICC stage, with most of the cases being diagnosed in stage IV. Furthermore, there was a significantly (p = 0.049) higher rate of bone infiltration in ERα-positive patients. Conclusion: Expression of ERα is rare in OSCC; however, it is associated with a dramatic decrease in OS in male patients. Further studies are necessary to confirm our results and to evaluate the exact mechanism underlying this observation. Hence, ERα-positive OSCC patients might benefit from an ER-based therapeutic (adjuvant) approach in the future.

Ischemic heart disease and cardioprotection: Focus on estrogenic hormonal setting and microvascular health

Ischemic Heart Disease (IHD) is a clinical condition characterized by insufficient blood flow to the cardiac tissue, and the consequent inappropriate oxygen and nutrients supply and metabolic waste removal in the heart. In the last decade a broad scientific literature has underlined the distinct mechanism of onset and the peculiar progress of IHD between female and male patients, highlighting the estrogenic hormonal setting as a key factor of these sex-dependent divergences. In particular, estrogen-activated cardioprotective pathways exert a pivotal role for the microvascular health, and their impairment, both physiologically and pathologically driven, predispose to vascular dysfunctions. Aim of this review is to summarize the current knowledge on the estrogen receptors localization and function in the cardiovascular system, particularly focusing on sex-dependent differences in microvascular vs macrovascular dysfunction and on the experimental models that allowed the researchers to reach the current findings and sketching the leading estrogen-mediated cardioprotective mechanisms.

Photoperiodic modulation of ovarian metabolic, survival, proliferation and gap junction markers in adult golden hamster, Mesocricetus auratus

Female reproductive physiology is greatly dependent on tight regulation of metabolic and survival factors. Photoperiod regulates female reproductive rhythms but very less information exists explaining whether photoperiod could modulate thyroid hormone homeostasis, metabolic/energy parameters along with survival, proliferation and gap junction proteins in the ovary of a long-day breeder, Mesocricetus auratus. Adult female hamsters were exposed to different photoperiodic regimes i.e., critical photoperiod (CP; 12.5L:11.5D), short photoperiod (SP; 8L:16D) and long photoperiod (LP; 16L:8D) for 12 weeks. LP upregulated thyroidal and gonadal activity as apparent by histoarchitecture, thyroid hormone profile [triiodothyronine (T3), thyroxin (T4) and thyroid stimulating hormone (TSH)], luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) levels when compared with SP exposed hamsters. Further, LP increased thyroid hormone receptor-α/deiodinase-2 (TRα/Dio-2), estrogen receptor-α (ERα)/aromatase and insulin receptor/glucose transporter-4 (IR/GLUT-4) expressions in ovary. Interestingly, ovarian sirtuin-1 (SIRT-1) expression was also upregulated under LP condition along with cell proliferation (proliferating cell nuclear antigen or PCNA), survival (B cell lymphoma-2 or Bcl-2) and gap junction (connexin-43) markers when compared to SP exposed hamsters. We also noted elevated levels of circulatory leptin, insulin along with melatonin and its receptor (MT-1) in ovary under SP condition. Thus, we suggest that photoperiod plays a vital role in regulation of thyroid and reproductive hormone homeostasis along with key metabolic and survival markers in the ovary of adult golden hamsters, M. auratus providing further insight into the regulation of female reproductive seasonality in a long-day breeder.

Sex Differences in Molecular Mechanisms of Cardiovascular Aging

Cardiovascular disease (CVD) is still the leading cause of illness and death in the Western world. Cardiovascular aging is a progressive modification occurring in cardiac and vascular morphology and physiology where increased endothelial dysfunction and arterial stiffness are observed, generally accompanied by increased systolic blood pressure and augmented pulse pressure. The effects of biological sex on cardiovascular pathophysiology have long been known. The incidence of hypertension is higher in men, and it increases in postmenopausal women. Premenopausal women are protected from CVD compared with age-matched men and this protective effect is lost with menopause, suggesting that sex-hormones influence blood pressure regulation. In parallel, the heart progressively remodels over the course of life and the pattern of cardiac remodeling also differs between the sexes. Lower autonomic tone, reduced baroreceptor response, and greater vascular function are observed in premenopausal women than men of similar age. However, postmenopausal women have stiffer arteries than their male counterparts. The biological mechanisms responsible for sex-related differences observed in cardiovascular aging are being unraveled over the last several decades. This review focuses on molecular mechanisms underlying the sex-differences of CVD in aging.

Nuclear Receptors and Clock Components in Cardiovascular Diseases

Cardiovascular diseases (CVD) are still the first cause of death worldwide. Their main origin is the development of atherosclerotic plaque, which consists in the accumulation of lipids and inflammatory leucocytes within the vascular wall of large vessels. Beyond dyslipidemia, diabetes, obesity, hypertension and smoking, the alteration of circadian rhythms, in shift workers for instance, has recently been recognized as an additional risk factor. Accordingly, targeting a pro-atherogenic pathway at the right time window, namely chronotherapy, has proven its efficiency in reducing plaque progression without affecting healthy tissues in mice, thus providing the rationale of such an approach to treat CVD and to reduce drug side effects. Nuclear receptors are transcriptional factors involved in the control of many physiological processes. Among them, Rev-erbs and RORs control metabolic homeostasis, inflammatory processes and the biological clock. In this review, we discuss the opportunity to dampen atherosclerosis progression by targeting such ligand-activated core clock components in a (chrono-)therapeutic approach in order to treat CVD.

Importins: Diverse roles in male fertility

Regulated nucleocytoplasmic transport is central to the changes in gene expression that underpin cellular development and homeostasis, including in the testis, and proteins in the importin family are the predominant facilitators of cargo transport through the nuclear envelope. Reports documenting cell-specific profiles of importin transcripts and proteins during spermatogenesis led us to hypothesize that importins facilitate developmental switches in the testis. More recently, importins have been shown to serve additional functions, both inside and outside the nucleus; these include acting as subcellular scaffolding, mediating cellular stress responses, and controlling transcription. This paper seeks to provide an overview and update on the functions of importin proteins, with a focus on testis development and spermatogenesis. We present an extended survey of importins by combining published single cell RNAseq data with immunohistochemistry on developing and adult mouse testes. This approach reinforces and broadens knowledge of importins in biological processes, including in spermatogenesis and during testis development, revealing additional avenues for impactful investigations.

Protective Effects of Estrogen on Cardiovascular Disease Mediated by Oxidative Stress

Perimenopause is an important stage of female senescence. Epidemiological investigation has shown that the incidence of cardiovascular disease in premenopausal women is lower than that in men, and the incidence of cardiovascular disease in postmenopausal women is significantly higher than that in men. This phenomenon reveals that estrogen has a definite protective effect on the cardiovascular system. In the cardiovascular system, oxidative stress is considered important in the pathogenesis of atherosclerosis, myocardial dysfunction, cardiac hypertrophy, heart failure, and myocardial ischemia. From the perspective of oxidative stress, estrogen plays a regulatory role in the cardiovascular system through the estrogen receptor, providing strategies for the treatment of menopausal women with cardiovascular diseases.

Signalling mechanisms in the cardiovascular protective effects of estrogen: With a focus on rapid/membrane signalling

In modern society, cardiovascular disease remains the biggest single threat to life, being responsible for approximately one third of worldwide deaths. Male prevalence is significantly higher than that of women until after menopause, when the prevalence of CVD increases in females until it eventually exceeds that of men. Because of the coincidence of CVD prevalence increasing after menopause, the role of estrogen in the cardiovascular system has been intensively researched during the past two decades in vitro, in vivo and in observational studies. Most of these studies suggested that endogenous estrogen confers cardiovascular protective and anti-inflammatory effects. However, clinical studies of the cardioprotective effects of hormone replacement therapies (HRT) not only failed to produce proof of protective effects, but also revealed the potential harm estrogen could cause. The "critical window of hormone therapy" hypothesis affirms that the moment of its administration is essential for positive treatment outcomes, pre-menopause (3-5 years before menopause) and immediately post menopause being thought to be the most appropriate time for intervention. Since many of the cardioprotective effects of estrogen signaling are mediated by effects on the vasculature, this review aims to discuss the effects of estrogen on vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) with a focus on the role of estrogen receptors (ERα, ERβ and GPER) in triggering the more recently discovered rapid, or membrane delimited (non-genomic), signaling cascades that are vital for regulating vascular tone, preventing hypertension and other cardiovascular diseases.

Sex-Gender Disparities in Cardiovascular Diseases: The Effects of Estrogen on eNOS, Lipid Profile, and NFATs During Catecholamine Stress

Cardiovascular diseases (CVDs) characterized by sex-gender differences remain a leading cause of death globally. Hence, it is imperative to understand the underlying mechanisms of CVDs pathogenesis and the possible factors influencing the sex-gender disparities in clinical demographics. Attempts to elucidate the underlying mechanisms over the recent decades have suggested the mechanistic roles of estrogen in modulating cardioprotective and immunoregulatory effect as a factor for the observed differences in the incidence of CVDs among premenopausal and post-menopausal women and men. This review from a pathomechanical perspective aims at illustrating the roles of estrogen (E2) in the modulation of stimuli signaling in the heart during chronic catecholamine stress (CCS). The probable mechanism employed by E2 to decrease the incidence of hypertension, coronary heart disease, and pathological cardiac hypertrophy in premenopausal women are discussed. Initially, signaling via estrogen receptors and β-adrenergic receptors (βARs) during physiological state and CCS were summarized. By reconciling the impact of estrogen deficiency and hyperstimulation of βARs, the discussions were centered on their implications in disruption of nitric oxide synthesis, dysregulation of lipid profiles, and upregulation of nuclear factor of activated T cells, which induces the aforementioned CVDs, respectively. Finally, updates on E2 therapies for maintaining cardiac health during menopause and suggestions for the advancement treatments were highlighted.

Sex Hormone Regulation of Proteins Modulating Mitochondrial Metabolism, Dynamics and Inter-Organellar Cross Talk in Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death in the U.S. and worldwide. Sex-related disparities have been identified in the presentation and incidence rate of CVD. Mitochondrial dysfunction plays a role in both the etiology and pathology of CVD. Recent work has suggested that the sex hormones play a role in regulating mitochondrial dynamics, metabolism, and cross talk with other organelles. Specifically, the female sex hormone, estrogen, has both a direct and an indirect role in regulating mitochondrial biogenesis via PGC-1α, dynamics through Opa1, Mfn1, Mfn2, and Drp1, as well as metabolism and redox signaling through the antioxidant response element. Furthermore, data suggests that testosterone is cardioprotective in males and may regulate mitochondrial biogenesis through PGC-1α and dynamics via Mfn1 and Drp1. These cell-signaling hubs are essential in maintaining mitochondrial integrity and cell viability, ultimately impacting CVD survival. PGC-1α also plays a crucial role in inter-organellar cross talk between the mitochondria and other organelles such as the peroxisome. This inter-organellar signaling is an avenue for ameliorating rampant ROS produced by dysregulated mitochondria and for regulating intrinsic apoptosis by modulating intracellular Ca²⁺ levels through interactions with the endoplasmic reticulum. There is a need for future research on the regulatory role of the sex hormones, particularly testosterone, and their cardioprotective effects. This review hopes to highlight the regulatory role of sex hormones on mitochondrial signaling and their function in the underlying disparities between men and women in CVD.

Estetrol prevents Western diet-induced obesity and atheroma independently of hepatic estrogen receptor α

Estetrol (E4), a natural estrogen synthesized by the human fetal liver, is currently evaluated in phase III clinical studies as a new menopause hormone therapy. Indeed, E4 significantly improves vasomotor and genito-urinary menopausal symptoms and prevents bone demineralization. Compared with other estrogens, E4 was found to have limited effects on coagulation factors in the liver of women allowing to expect less thrombotic events. To fully delineate its clinical potential, the aim of this study was to assess the effect of E4 on metabolic disorders. Here, we studied the pathophysiological consequences of a Western diet (42% kcal fat, 0.2% cholesterol) in ovariectomized female mice under chronic E4 treatment. We showed that E4 reduces body weight gain and improves glucose tolerance in both C57Bl/6 and LDLR^-/- mice. To evaluate the role of hepatic estrogen receptor (ER) α in the preventive effect of E4 against obesity and associated disorders such as atherosclerosis and steatosis, mice harboring a hepatocyte-specific ERα deletion (LERKO) were crossed with LDLR^-/- mice. Our results demonstrated that, whereas liver ERα is dispensable for the E4 beneficial actions on obesity and atheroma, it is necessary to prevent steatosis in mice. Overall, these findings suggest that E4 could prevent metabolic, hepatic, and vascular disorders occurring at menopause, extending the potential medical interest of this natural estrogen as a new hormonal treatment.NEW & NOTEWORTHY Estetrol prevents obesity, steatosis, and atherosclerosis in mice fed a Western diet. Hepatic ERα is necessary for the prevention of steatosis, but not of obesity and atherosclerosis.

An Overview of Similarities and Differences in Metabolic Actions and Effects of Central Nervous System Between Glucagon-Like Peptide-1 Receptor Agonists (GLP-1RAs) and Sodium Glucose Co-Transporter-2 Inhibitors (SGLT-2is)

GLP-1 receptor agonists (GLP-1RAs) and SGLT-2 inhibitors (SGLT-2is) are novel antidiabetic medications associated with considerable cardiovascular benefits therapying treatment of diabetic patients. GLP-1 exhibits atherosclerosis resistance, whereas SGLT-2i acts to ameliorate the neuroendocrine state in the patients with chronic heart failure. Despite their distinct modes of action, both factors share pathways by regulating the central nervous system (CNS). While numerous preclinical and clinical studies have demonstrated that GLP-1 can access various nuclei associated with energy homeostasis and hedonic eating in the CNS via blood-brain barrier (BBB), research on the activity of SGLT-2is remains limited. In our previous studies, we demonstrated that both GLP-1 receptor agonists (GLP-1RAs) liraglutide and exenatide, as well as an SGLT-2i, dapagliflozin, could activate various nuclei and pathways in the CNS of Sprague Dawley (SD) rats and C57BL/6 mice, respectively. Moreover, our results revealed similarities and differences in neural pathways, which possibly regulated different metabolic effects of GLP-1RA and SGLT-2i via sympathetic and parasympathetic systems in the CNS, such as feeding, blood glucose regulation and cardiovascular activities (arterial blood pressure and heart rate control). In the present article, we extensively discuss recent preclinical studies on the effects of GLP-1RAs and SGLT-2is on the CNS actions, with the aim of providing a theoretical explanation on their mechanism of action in improvement of the macro-cardiovascular risk and reducing incidence of diabetic complications. Overall, these findings are expected to guide future drug design approaches.

[Low-magnitude vibration promotes osteogenesis of osteoblasts in ovariectomized osteoporotic rats via the estrogen receptor ]

The purpose of this study was to investigate the effect of low-magnitude vibration on osteogenesis of osteoblasts in ovariectomized rats with osteoporosis via estrogen receptor α(ERα). The mRNA expression of osteogenic markers were examined with qRT-PCR, based on which the optimal vibration parameter for promoting osteogenesis was determined (45 Hz × 0.9 g, g = 9.8 m/s2). Then we loaded the optimal vibration parameter on the osteoblasts of ovariectomized rats with osteoporosis. The protein expression of osteogenic markers and ERα were detected with Western blot; the distribution of ERα was examined with immunofluorescence technique. Finally, through inhibiting the expression of ERα with estrogen receptor inhibitor ICI182780, the protein and mRNA expression of osteogenic markers were examined. First, the results showed that low-magnitude vibration could promote the expression of osteogenic markers and ERα in osteoblasts of ovariectomized rats with osteoporosis (P < 0.05), and make ERα transfer to the nucleus. On the other hand, the results also showed that after inhibiting the expression of ERα in osteoblasts of ovariectomized rats with osteoporosis, the protein and mRNA expression of osteogenic marker were decreased (P < 0.05). In our study, low-magnitude vibration played an important role in the osteogenesis of osteoblasts in ovariectomized rats with osteoporosis through increasing the expression and causing translocation of ERα. Furthermore, it provides a theoretical basis for the application of low-magnitude vibration in the prevention and treatment of postmenopausal osteoporosis.

Selective Targeting of Non-nuclear Estrogen Receptors with PaPE-1 as a New Treatment Strategy for Alzheimer's Disease

Alzheimer’s disease (AD) is a multifactorial and severe neurodegenerative disorder characterized by progressive memory decline, the presence of Aβ plaques and tau tangles, brain atrophy, and neuronal loss. Available therapies provide moderate symptomatic relief but do not alter disease progression. This study demonstrated that PaPE-1, which has been designed to selectively activate non-nuclear estrogen receptors (ERs), has anti-AD capacity, as evidenced in a cellular model of the disease. In this model, the treatment of mouse neocortical neurons with Aβ (5 and 10 μM) induced apoptosis (loss of mitochondrial membrane potential, activation of caspase-3, induction of apoptosis-related genes and proteins) accompanied by increases in levels of reactive oxygen species (ROS) and lactate dehydrogenase (LDH) as well as reduced cell viability. Following 24 h of exposure, PaPE-1 inhibited Aβ-evoked effects, as shown by reduced parameters of neurotoxicity, oxidative stress, and apoptosis. Because PaPE-1 downregulated Aβ-induced Fas/FAS expression but upregulated that of Aβ-induced FasL, the role of PaPE-1 in controlling the external apoptotic pathway is controversial. However, PaPE-1 normalized Aβ-induced loss of mitochondrial membrane potential and restored the BAX/BCL2 ratio, suggesting that the anti-AD capacity of PaPE-1 particularly relies on inhibition of the mitochondrial apoptotic pathway. These data provide new evidence for an anti-AD strategy that utilizes the selective targeting of non-nuclear ERs with PaPE-1.

Ovariectomized rodents as a menopausal metabolic syndrome model. A minireview

Bilateral ovariectomy is the best characterized and the most reported animal model of human menopause. Ovariectomized rodents develop insulin resistance (IR) and visceral obesity, the main risk factors in the pathophysiology of metabolic syndrome (MS). These alterations are a consequence of hypoestrogenic status, which produces an augment of visceral fat, high testosterone levels (hyperandrogenism), as well as inflammation, oxidative stress, and metabolic complications, such as dyslipidemia, hepatic steatosis, and endothelial dysfunction, among others. Clinical trials have reported that menopause per se increases the severity and incidence of MS, and causes the highest mortality due to cardiovascular disease in women. Despite all the evidence, there are no reports that clarify the influence of estrogenic deficiency as a cause of MS. In this review, we provide evidence that ovariectomized rodents can be used as a menopausal metabolic syndrome model for evaluating and discovering new, safe, and effective therapeutic approaches in the treatment of cardiometabolic complications associated to MS during menopause.

Daidzein promotes milk synthesis and proliferation of mammary epithelial cells via the estrogen receptor α-dependent NFκB1 activation

Isoflavones possess a wide range of physiological effects. However, it is still unclear whether isoflavones can promote milk synthesis in mammary gland. This study aimed to determine the effects of a main soy isoflavone, daidzein, on milk synthesis and proliferation of mammary epithelial cells (MECs) and reveal the underlying molecular mechanism. Primary bovine MECs were treated with different concentrations of daidzein (0, 5, 10, 20, 40, and 80 μM). Daidzein dose-dependently promoted α- and β-casein and lipid synthesis, cell cycle transition, and cell amount, with the best stimulatory effect at 20 μM. Daidzein also stimulated mTOR activation and Cyclin D1 and SREBP-1c expression. Daidzein induced the expression and nuclear localization of estrogen receptor α (ERα), and ERα knockdown blocked the stimulation of daidzein on these above signaling pathways. ERα knockdown also abolished the stimulation of daidzein on NFκB1 expression and phosphorylation, and NFκB1 was required for daidzein to enhance the mTOR, Cyclin D1 and SREBP-1c signaling pathways. In summary, our findings reveal that daidzein stimulates milk synthesis and proliferation of MECs via the ERα-dependent NFκB1 activation.

Secondary Resistant Mutations to Small Molecule Inhibitors in Cancer Cells

Secondary resistant mutations in cancer cells arise in response to certain small molecule inhibitors. These mutations inevitably cause recurrence and often progression to a more aggressive form. Resistant mutations may manifest in various forms. For example, some mutations decrease or abrogate the affinity of the drug for the protein. Others restore the function of the enzyme even in the presence of the inhibitor. In some cases, resistance is acquired through activation of a parallel pathway which bypasses the function of the drug targeted pathway. The Catalogue of Somatic Mutations in Cancer (COSMIC) produced a compendium of resistant mutations to small molecule inhibitors reported in the literature. Here, we build on these data and provide a comprehensive review of resistant mutations in cancers. We also discuss mechanistic parallels of resistance.

Estrogenic control of mitochondrial function

Sex-based differences in human disease are caused in part by the levels of endogenous sex steroid hormones which regulate mitochondrial metabolism. This review updates a previous review on how estrogens regulate metabolism and mitochondrial function that was published in 2017. Estrogens are produced by ovaries and adrenals, and in lesser amounts by adipose, breast stromal, and brain tissues. At the cellular level, the mechanisms by which estrogens regulate diverse cellular functions including reproduction and behavior is by binding to estrogen receptors α, β (ERα and ERβ) and G-protein coupled ER (GPER1). ERα and ERβ are transcription factors that bind genomic and mitochondrial DNA to regulate gene transcription. A small proportion of ERα and ERβ interact with plasma membrane-associated signaling proteins to activate intracellular signaling cascades that ultimately alter transcriptional responses, including mitochondrial morphology and function. Although the mechanisms and targets by which estrogens act directly and indirectly to regulate mitochondrial function are not fully elucidated, it is clear that estradiol regulates mitochondrial metabolism and morphology via nuclear and mitochondrial-mediated events, including stimulation of nuclear respiratory factor-1 (NRF-1) transcription that will be reviewed here. NRF-1 is a transcription factor that interacts with coactivators including peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC-1α) to regulate nuclear-encoded mitochondrial genes. One NRF-1 target is TFAM that binds mtDNA to regulate its transcription. Nuclear-encoded miRNA and lncRNA regulate mtDNA-encoded and nuclear-encoded transcripts that regulate mitochondrial function, thus acting as anterograde signals. Other estrogen-regulated mitochondrial activities including bioenergetics, oxygen consumption rate (OCR), and extracellular acidification (ECAR), are reviewed.

Sirt3 Exerts Its Tumor-Suppressive Role by Increasing p53 and Attenuating Response to Estrogen in MCF-7 Cells

Estrogen (E2) is a major risk factor for the initiation and progression of malignancy in estrogen receptor (ER) positive breast cancers, whereas sirtuin 3 (Sirt3), a major mitochondrial NAD⁺-dependent deacetylase, has the inhibitory effect on the tumorigenic properties of ER positive MCF-7 breast cancer cells. Since it is unclear if this effect is mediated through the estrogen receptor alpha (ERα) signaling pathway, in this study, we aimed to determine if the tumor-suppressive function of Sirt3 in MCF-7 cells interferes with their response to E2. Although we found that Sirt3 improves the antioxidative response and mitochondrial fitness of the MCF-7 cells, it also increases DNA damage along with p53, AIF, and ERα expression. Moreover, Sirt3 desensitizes cells to the proliferative effect of E2, affects p53 by disruption of the ERα–p53 interaction, and decreases proliferation, colony formation, and migration of the cells. Our observations indicate that these tumor-suppressive effects of Sirt3 could be reversed by E2 treatment only to a limited extent which is not sufficient to recover the tumorigenic properties of the MCF-7 cells. This study provides new and interesting insights with respect to the functional role of Sirt3 in the E2-dependent breast cancers.

Sex differences in metabolic regulation and diabetes susceptibility

Gender and biological sex impact the pathogenesis of numerous diseases, including metabolic disorders such as diabetes. In most parts of the world, diabetes is more prevalent in men than in women, especially in middle-aged populations. In line with this, considering almost all animal models, males are more likely to develop obesity, insulin resistance and hyperglycaemia than females in response to nutritional challenges. As summarised in this review, it is now obvious that many aspects of energy balance and glucose metabolism are regulated differently in males and females and influence their predisposition to type 2 diabetes. During their reproductive life, women exhibit specificities in energy partitioning as compared with men, with carbohydrate and lipid utilisation as fuel sources that favour energy storage in subcutaneous adipose tissues and preserve them from visceral and ectopic fat accumulation. Insulin sensitivity is higher in women, who are also characterised by higher capacities for insulin secretion and incretin responses than men; although, these sex advantages all disappear when glucose tolerance deteriorates towards diabetes. Clinical and experimental observations evidence the protective actions of endogenous oestrogens, mainly through oestrogen receptor α activation in various tissues, including the brain, the liver, skeletal muscle, adipose tissue and pancreatic beta cells. However, beside sex steroids, underlying mechanisms need to be further investigated, especially the role of sex chromosomes, fetal/neonatal programming and epigenetic modifications. On the path to precision medicine, further deciphering sex-specific traits in energy balance and glucose homeostasis is indeed a priority topic to optimise individual approaches in type 2 diabetes prevention and treatment.

In vitro assessment of effects of persistent organic pollutants on the transactivation of estrogen receptor α and β (ERα and ERβ) from the Baikal seal (Pusa sibirica)

To assess the effect of exposure to persistent organic pollutants (POPs) on the estrogen receptor (ER) signaling pathway in Baikal seals (Pusa sibirica), we investigated the molecular characterizations and functions of two Baikal seal ER (bsER) isoforms, bsERα and bsERβ. The bsERα and bsERβ cDNA clones isolated have an open reading frame of 595 and 530 amino acid residues, respectively. The tissue distribution analyses of bsER mRNAs showed that bsERα transcripts were primarily found in the ovary and uterus, and bsERβ in the muscle in wild Baikal seals. The immunofluorescence staining assay showed that 17β-estradiol (E₂) treatment promoted the nuclear translocation of in vitro-expressed bsERα. Transient transfection of bsERα in U2OS cells enhanced the transcription of pS2, an ER target gene of E₂. We then measured bsER-mediated transactivation potencies of POPs in an in vitro reporter gene assay system, in which a bsERα or bsERβ expression vector was transfected into COS-1 cells. For comparison, transactivation potencies of POPs on mouse ERs (mERα and mERβ) were also evaluated in the same manner. Results showed significant dose-dependent responses of bsERs and mERs when treated with p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE). bsERs and mERs showed no response when exposed to polychlorinated biphenyls (PCBs) or 2,3,7,8-tetrachlorodibenzo-p-dioxin. Comparison of the dose-response curves of DDTs across species (bsERs vs. mERs) showed that bsERα had a response similar to mERα, but bsERβ was less sensitive than mERβ. Comparing the lowest observable effective concentrations of p,p'-DDT (2.8 μM) and p,p'-DDE (10 μM) for in vitro bsERα-mediated transactivation with their hepatic concentrations in wild Baikal seals indicated that some individuals accumulated these compounds at levels comparable to the effective concentrations, suggesting the potential disruption of the bsERα signaling pathway in the wild population by these compounds. Co-transfection experiments with bsER and the aryl hydrocarbon receptor (AHR) suggested that high accumulation of estrogenic compounds exerts a synergistic effect with dioxin-like congeners on ER signaling through AHR activation in the wild seal population.

Estrogen Contributions to Microvascular Dysfunction Evolving to Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a syndrome involving microvascular dysfunction. No treatment is available yet and as the HFpEF patient group is expanding due to the aging population, more knowledge on dysfunction of the cardiac microvasculature is required. Endothelial dysfunction, impaired angiogenesis, (perivascular) fibrosis and the pruning of capillaries (rarefaction) may all contribute to microvascular dysfunction in the heart and other organs, e.g., the kidneys. The HFpEF patient group consists mainly of post-menopausal women and female sex itself is a risk factor for this syndrome. This may point toward a role of estrogen depletion after menopause in the development of HFpEF. Estrogens favor the ratio of vasodilating over vasoconstricting factors, which results in an overall lower blood pressure in women than in men. Furthermore, estrogens improve angiogenic capacity and attenuate (perivascular) fibrosis formation. Therefore, we hypothesize that the drop of estrogen levels after menopause contributes to myocardial microvascular dysfunction and renders post-menopausal women more vulnerable for heart diseases that involve the microvasculature. This review provides a detailed summary of molecular targets of estrogen, which might guide future research and treatment options.

Estrogen-mediated protection against coronary heart disease: The role of the Notch pathway

Estrogen regulates a plethora of biological processes, under physiological and pathological conditions, by affecting key pathways involved in the regulation of cell proliferation, fate, survival and metabolism. The Notch receptors are mediators of communication between adjacent cells and are key determinants of cell fate during development and in postnatal life. Crosstalk between estrogen and the Notch pathway intervenes in many processes underlying the development and maintenance of the cardiovascular system. The identification of molecular mechanisms underlying the interaction between these types of endocrine and juxtacrine signaling are leading to a deeper understanding of physiological conditions regulated by these steroid hormones and, potentially, to novel therapeutic approaches to prevent pathologies linked to reduced levels of estrogen, such as coronary heart disease, and cardiotoxicity caused by hormone therapy for estrogen-receptor-positive breast cancer.

17β-estradiol inhibits human umbilical vascular endothelial cell senescence by regulating autophagy via p53

Vascular endothelial cell (VEC) senescence is an initiating factor in numerous cardiovascular diseases. Recent studies showed that 17β-estradiol (17β-E2), an estrogen with numerous biological activities such as inhibition of atherosclerosis, protects VECs from senescence. However, the effects of 17β-E2 on human umbilical VECs (HUVECs) remain unknown. This study investigated the anti-senescent effect of 17β-E2 on HUVECs and explored the underlying mechanism with respect to autophagy and p53 activity. First, rapamycin and 3-methyladenine were used to clarify the relationship between autophagy and senescence in HUVECs, and an inverse relationship was demonstrated. Next, the effect of 17β-E2 on H₂O₂-induced senescence of HUVECs was examined. Increased autophagy induced by 17β-E2 inhibited H₂O₂-induced senescence of HUVECs, increased cell viability, and maintained HUVEC morphology. 17β-E2 pre-treatment also decreased cell cycle arrest, decreased the dephosphorylation of Rb, decreased the production of ET-1, and increased the production of NO. Most importantly, 17β-E2 pre-treatment increased autophagy by activating p53 and its downstream effector p53-upregulated modulator of apoptosis (PUMA). Overall, our data indicate the critical role of autophagy in the anti-senescent effect of 17β-E2 on HUVECs.