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Functional and physiological genomics of estrogen-related receptors (ERRs) in health and disease
Abstract
Orphan nuclear receptors, in a manner comparable to classic steroid hormone receptors, regulate key developmental and physiological processes. However, the lack of appropriate pharmacological tools has often hindered the identification and study of their biological functions. In this review, we demonstrate that functional and physiological genomics are effective alternatives to discover biological functions associated with orphan nuclear receptors. Indeed, we document that these approaches have allowed for the unambiguous identification of the estrogen-related receptors (ERRs) α, β, and γ (NR3B1, 2, and 3) as global regulators of cellular energy metabolism. We further show that although the three ERR isoforms control analogous gene networks, each isoform performs unique biological functions in a tissue-specific manner in response to a variety of physiological stressors. Finally, we discuss how the activity of the three ERR isoforms contributes to the development and progression of metabolic diseases as well as to the adaptation of cancer cells to their unique bioenergetic requirement. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.
... Important coactivators are PGC1-a and PGC1-b, and members of the steroid receptor activator (SRC) family (Huss, Kopp, and Kelly 2002;Gaillard, Dwyer, and McDonnell 2007;W. Xie et al. 1999;Hong, Yang, and Stallcup 1999;Deblois and Giguère 2011). ...
... Expression profiles obtained in mice, showed that ERRa is found in each cell and tissue analyzed and ERRg and ERRb are widely expressed, with some exceptions, as listed below Deblois and Giguère 2011;. ...
... ChIP studies revealed that ERR paralogs bind mostly to their ERRE motif on genomic DNA and have been identified at the promoter regions of approximatively 700 genes encoding mitochondrial proteins and at other genes involved in translation, glucosamine pathway, energy sensing and growth factor/insulin signaling (Deblois et al. 2009;Fullwood et al. 2009;Sonoda et al. 2007;Deblois and Giguère 2011). ...
The abundance of genetic mobile elements in our DNA has a critical impact on the evolution and function of the human genome. Even if most transposable elements are inactive due to the accumulation of mutational events, the Long INterspersed Element-1 (LINE-1 or L1) retrotransposon continues to diversify and impact our genome, being involved in the evolution of modern humans and in the appearance of genetic diseases or in tumorigenesis. L1 forms 17% of human DNA. It is autonomously active being replicated through an RNA-mediated ‘copy-and-paste’ mechanism. The L1 element encodes two proteins, ORF1p and ORF2p, which associate with the L1 mRNA to form L1 ribonucleoprotein particles, the core of the retrotransposition machinery. However, little is known about the cellular pathways involved in L1 replication. Our laboratory has discovered by yeast 2-hybrid screens an interaction between L1 ORF2p and the estrogen-related receptor α (ERRα), a member of the nuclear receptor family. Here, we confirmed and extended this observation to several other members of the steroid receptor superfamily using a fluorescent two-hybrid assay (F2H) in human cultured cells. To get further insight into the potential role of ERR in L1 replication cycle, we performed ERR siRNA-mediated knock-down and overexpression experiments, which suggest that ERR is a positive regulator of retrotransposition. Moreover, the artificial tethering and concentration of ERR to a large and repetitive genomic array inhibits retrotransposition. Collectively, these data link steroid signaling pathways with the post-translational regulation of L1 retrotransposition, suggesting a model by which ERRα, and probably several other nuclear receptors, can recruit the L1 RNP to specific chromosomal locations, acting as tethering factors.
... The Estrogen-Related Receptors (ERRα, β and γ in mammals) form a subfamily of orphan (i.e., lacking an identified natural ligand) NRs. They are expressed in several tissues during embryologic development and in the adult, and display various physiological and pathological functions [10][11][12][13]. The ligand-independent transcriptional activity of ERRs has been noted for several years. ...
... The most-studied member of the ERR family, ERRα, is involved in various functions related to energy metabolism in tissues displaying high energy demands, such as liver, muscles, adipose tissues or heart [11,17,18]. It has also important roles in osteogenesis, immunity, brain functions and tumorigenesis [19][20][21]. ...
Estrogen-related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several cell types and they display various functions in normal and pathological contexts. Amongst others, they are notably involved in bone homeostasis, energy metabolism and cancer progression. In contrast to other nuclear receptors, the activities of the ERRs are apparently not controlled by a natural ligand but they rely on other means such as the availability of transcriptional co-regulators. Here we focus on ERRα and review the variety of co-regulators that have been identified by various means for this receptor and their reported target genes. ERRα cooperates with distinct co-regulators to control the expression of distinct sets of target genes. This exemplifies the combinatorial specificity of transcriptional regulation that induces discrete cellular phenotypes depending on the selected coregulator. We finally propose an integrated view of the ERRα transcriptional network.
... For a given TFCR, BipotentR derives its core binding sites by combining all ChIP-seq samples and then estimates its binding potential while controlling for sample-specific confounding effects using a linear mixed model (Methods). BipotentR identified previously known [e.g., ESRRA and BCL3 regulate OXPHOS (35,36); PPARG and CEBPB regulate FA and glycolysis (37,38)] and new TFCRs for each pathway ( Fig. 1B; Supplementary Table S1). It then prioritized the subset of these regulators that can affect multiple energy metabolism pathways ("master regulators") by ranking TFCRs according to their average overall binding affinities across pathways. ...
... An orphan nuclear receptor, ESRRA, was predicted to have the highest immune-metabolic potential. Targeting ESRRA in immunodeficient models has been shown to inhibit tumors by direct cell-intrinsic mechanisms (35,56), ...
Drugs that kill tumors through multiple mechanisms have the potential for broad clinical benefits. Here, we first developed an in silico multiomics approach (BipotentR) to find cancer cell-specific regulators that simultaneously modulate tumor immunity and another oncogenic pathway and then used it to identify 38 candidate immune-metabolic regulators. We show the tumor activities of these regulators stratify patients with melanoma by their response to anti-PD-1 using machine learning and deep neural approaches, which improve the predictive power of current biomarkers. The topmost identified regulator, ESRRA, is activated in immunotherapy-resistant tumors. Its inhibition killed tumors by suppressing energy metabolism and activating two immune mechanisms: (i) cytokine induction, causing proinflammatory macrophage polarization, and (ii) antigen-presentation stimulation, recruiting CD8+ T cells into tumors. We also demonstrate a wide utility of BipotentR by applying it to angiogenesis and growth suppressor evasion pathways. BipotentR (http://bipotentr.dfci.harvard.edu/) provides a resource for evaluating patient response and discovering drug targets that act simultaneously through multiple mechanisms.
Significance:
BipotentR presents resources for evaluating patient response and identifying targets for drugs that can kill tumors through multiple mechanisms concurrently. Inhibition of the topmost candidate target killed tumors by suppressing energy metabolism and effects on two immune mechanisms.
... ERRα binds on an extended estrogen response element half-site which was later named as ERRα response element (ERRE) (3). Despite this, ERRα does not bind natural estrogens, nor does it directly participate in classic estrogen signaling pathways or biological processes (11). ERRα was originally designated as an orphan nuclear receptor because of the lack of natural ligand, but recent study suggested that cholesterol (2) is possibly an endogenous ligand of ERRα and mediates its biological functions in bone, macrophage and muscle cells (43). ...
... ERRα had been identified as a primary effector of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) that is a key coactivator in energy homeostasis through analyses of transcriptional profiles using a computational strategy (16,17). A master regulatory role of ERRα in metabolism was further supported by reduced expression of ERRα-regulated genes in insulin-resistant subjects, while overexpression of a chimeric, constitutively active form of ERRα was sufficient to induce mitochondrial gene expression and biogenesis (11). Studies have also confirmed that ERRα participates in transcriptional regulation of specific genes required for fatty acid oxidation (18). ...
Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent forms of chronic liver diseases and is causally linked to hepatic insulin resistance and reduced fatty acid oxidation. Therapeutic treatments targeting both hepatic insulin resistance and lipid oxidative metabolism are considered as feasible strategies to alleviate this disease. Emerging evidence suggests Estrogen-Related Receptor alpha (ERRα), the first orphan nuclear receptor identified, as a master regulator in energy homeostasis by controlling glucose and lipid metabolism. Small molecules improving the functions of ERRα may provide a new option for management of NAFLD. In the present study, by using liver-specific Errα knockout mouse (Errα-LKO), we showed that liver-specific deletion of ERRα exacerbated diet-evoked fatty liver, hepatic and systemic insulin resistance in mice. A potent and selective ERRα agonist JND003 (7) was also discovered. In vitro and in vivo investigation demonstrated that the compound enhanced the transactivation of ERRα downstream target genes, which was accompanied by improved insulin sensitivity and fatty liver symptoms. Furthermore, the therapeutic effects were completely abolished in Errα-LKO mice, indicative of its on-target efficacy. Our study thus suggests that hepatic ERRα is a viable target for NAFLD and that ERRα agonist may serve as an intriguing pharmacological option for management of metabolic diseases.
... In mammals, there are three subtypes of ERRs, ERRα, ERRβ, and ERRγ, which play important roles in physiological and pathological functions (Deblois and Giguere, 2011). In particular, ERRs are closely associated with tumorigenesis. ...
... ERRβ is shown to inhibit the growth of prostate cancer (Misawa and Inoue, 2015). In addition, ERRs play vital roles in energy metabolism, mitochondrial biogenesis, oxidative phosphorylation, fat metabolism, and cell growth (Carrier et al., 2004;Tremblay and Giguere, 2007;Deblois and Giguere, 2011;Eichner and Giguere, 2011;Sailland et al., 2014). ...
Estrogen-related receptor (ERR) is an orphan nuclear receptor that was first discovered in animals, and play an important role in metabolism, development, and reproduction. Despite extensive research on the function of ERR, its transcriptional regulation mechanism remains unclear. In this study, we obtained the upstream region of Bombyx mori ERR ( BmERR ) and confirmed the promoter activity of this region. Interestingly, we found that 10 and 50 nM 20-hydroxyecdysone (20E) up-regulated the transcriptional activity of BmERR promoter. In addition, eight putative ecdysone response elements (EcREs) were predicted in the upstream sequence of BmERR . Based on their positions, the upstream sequence of BmERR was truncated into different fragments. Finally, an EcRE-like sequence (5′-AGTGCAGTAAACTGT-3′) was identified. Electrophoretic mobility shift assay (EMSA) and cell transfection experiments confirmed that this motif specifically binds to the complex formed between ecdysone receptor (BmEcR) and the ultraspiracle (BmUSP), a key complex in the 20E signaling pathway. Interference of BmERR or BmEcR mRNA in the embryonic cells of Bombyx mori significantly affected the expression of BmEcR and BmUSP . Overall, these results suggested that an EcRE element was identified from BmERR, and this will help understanding the detailed regulatory mechanism of ERR in insects.
... ERRs are orphan nuclear receptors that possess high similarity sequence DNA-binding domains of estrogen receptors (ERs) [22]. However, ERRs do not bind to 17β-estradiol as an estrogen ligand [23]. ERRs are involved in various metabolic processes, including alcohol, bone, cholesterol, glucose, iron, and lipid metabolism [24]. ...
... ERRs are involved in various metabolic processes, including alcohol, bone, cholesterol, glucose, iron, and lipid metabolism [24]. They are expressed in the liver, muscle, heart, and bone [23,24]. Our group has reported that ERRγ is a novel catabolic regulator of OA pathogenesis [7]. ...
Estrogen-related receptors (ERRs) are the first identified orphan nuclear receptors. The ERR family consists of ERRα, ERRβ, and ERRγ, regulating diverse isoform-specific functions. We have reported the importance of ERRγ in osteoarthritis (OA) pathogenesis. However, therapeutic approaches with ERRγ against OA associated with inflammatory mechanisms remain limited. Herein, we examined the therapeutic potential of a small-molecule ERRγ inverse agonist, GSK5182 (4-hydroxytamoxifen analog), in OA, to assess the relationship between ERRγ expression and pro-inflammatory cytokines in mouse articular chondrocyte cultures. ERRγ expression increased following chondrocyte exposure to various pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. Pro-inflammatory cytokines dose-dependently increased ERRγ protein levels. In mouse articular chondrocytes, adenovirus-mediated ERRγ overexpression upregulated matrix metalloproteinase (MMP)-3 and MMP-13, which participate in cartilage destruction during OA. Adenovirus-mediated ERRγ overexpression in mouse knee joints or ERRγ transgenic mice resulted in OA. In mouse joint tissues, genetic ablation of Esrrg obscured experimental OA. These results indicate that ERRγ is involved in OA pathogenesis. In mouse articular chondrocytes, GSK5182 inhibited pro-inflammatory cytokine-induced catabolic factors. Consistent with the in vitro results, GSK5182 significantly reduced cartilage degeneration in ERRγ-overexpressing mice administered intra-articular Ad-Esrrg. Overall, the ERRγ inverse agonist GSK5182 represents a promising therapeutic small molecule for OA.
... Consistent with prior studies [42,43], reduced expression of fatty acids oxidation genes and elevated expression of lipogenic genes were found in the liver of ERRαLKO mice which may contribute to lipids accumulation ( Figure S3C). To further ascertain how ERRα governs hepatic VLDL secretion, we rescued ERRα expression by adenovirus in ERRαLKO primary hepatocytes. ...
... As a transcription factor that targets multiple genes, ERRα is best known for its regulatory roles in mitochondrial biogenesis and oxidative phosphorylation [42,43]; therefore, loss of ERRα function is expected to have an impact on fatty acid oxidation. Besides these well-established roles, there are hints that ERRα has an impact on lipid synthesis as genes involved in fatty acid synthesis such as fatty acid synthase (Fasn) and sterol regulatory element binding protein-1 (Srebp1) [52] are upregulated in the liver of ERRα whole-body knockout mice [43]. ...
Rationale: Men and postmenopausal women are more prone to developing non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) than premenopausal women. However, the pathological links and underlying mechanisms of this disparity are still elusive. The sex-difference in hepatic very low-density lipoprotein (VLDL) assembly and secretion may contribute to NAFLD development. Estrogen-related receptor alpha (ERRα) is a key regulator of several metabolic processes. We hypothesized that ERRα plays a role contributing to the sex-difference in hepatic VLDL assembly and secretion.
Methods: VLDL secretion and essential genes governing said process were assessed in male and female mice. Liver-specific ERRα-deficient (ERRαLKO) mice were generated to assess the rate of hepatic VLDL secretion and alteration in target gene expression. Overexpression of either microsomal triglyceride transfer protein (Mttp) or phospholipase A2 G12B (Pla2g12b) by adenovirus was performed to test if the fatty liver phenotype in male ERRαLKO mice was due to defects in hepatic VLDL secretion. Female ERRαLKO mice were put on a diet high in saturated fat, fructose and cholesterol (HFHC) to promote NASH development. Wild type female mice were either ovariectomized or treated with tamoxifen to induce a state of estrogen deficiency or disruption in estrogen signaling. Adenovirus was used to overexpress ERRα in these mice to test if ERRα was sufficient to rescue the suppressed VLDL secretion due to estrogen dysfunction. Finally, wild type male mice on a high-fat diet (HFD) were treated with an ERRα inverse agonist to assess if suppressing ERRα activity pharmacologically would lead to fatty liver development.
Results: ERRα is an indispensable mediator modulating hepatic triglyceride-rich very low-density lipoprotein (VLDL-TG) assembly and secretion through coordinately controlling target genes apolipoprotein B (Apob), Mttp and Pla2g12b in a sex-different manner. Hepatic VLDL-TG secretion is blunted in ERRαLKO mice, leading to hepatosteatosis which exacerbates endoplasmic reticulum stress and inflammation paving ways for NASH development. Importantly, ERRα acts downstream of estrogen/ERα signaling in contributing to the sex-difference in hepatic VLDL secretion effecting hepatic lipid homeostasis.
Conclusions: Our results highlight ERRα as a key mediator which contributes to the sex disparity in NAFLD development, suggesting that selectively restoring ERRα activity in the liver may be a novel strategy for treating NAFLD/NASH.
... The nuclear receptor estrogen-related receptor alpha (ERR; NR3B1) plays important roles in energy metabolism by regulating the expression of genes involved in cellular energy metabolism, including those encoding enzymes in the oxidative phosphorylation (OXPHOS), tricarboxylic acid (TCA) cycle, glycolysis and in anabolic biosynthesis pathways like lipid, amino-acid and nucleic acid biosynthesis [17][18][19]. Importantly, ERR adapts the metabolic pathways to fuel tumor growth via its interaction with the peroxisome proliferator-activated receptor coactivator-1 (PGC-1 ) [20,21]. ...
... Consistently, ChIP-on-chip studies demonstrated that only approximately 18% of ER target genes are co-regulated by ERR in MCF7 cells [21]. Furthermore, despite a high degree of amino acid similarity (68%) in the DNA binding domains (DBDs) of ERRs and ERα, ERRs do not bind strongly to perfect palindromic ER response elements [19,21,25]. In addition, several studies have shown that pharmacological modulation of ERRα activity with inverse agonists decreases the proliferation of both ER-positive and -negative breast cancer cells in vitro as well as tumorigenicity in nude mice [17,[26][27][28]. ...
Breast cancer is the 2nd leading cause of cancer-related death among women. Increased risk of breast cancer has been associated with high dietary cholesterol intake. However, the underlying mechanisms are not known. The nuclear receptor, estrogen-related receptor alpha (ERRa), plays an important role in breast cancer cell metabolism, and its overexpression has been linked to poor survival. Here we identified cholesterol as an endogenous ligand of ERRa by purification from human pregnancy serum using a GST-ERRa affinity column and liquid chromatography-tandem mass spectrometry (LC-MS/MS). We show that cholesterol interacts with ERRa and induces its transcriptional activity in estrogen receptor positive (ER+) and triple negative breast cancer (TNBC) cells. In addition, we show that cholesterol enhances ERRa-PGC-1a interaction, induces ERRa expression itself, augments several metabolic target genes of ERRa, and increases cell proliferation and migration in both ER+ and TNBC cells. Furthermore, the stimulatory effect of cholesterol on metabolic gene expression, cell proliferation, and migration requires the ERRa pathway. These findings provide a mechanistic explanation for the increased breast cancer risk associated with high dietary cholesterol and possibly the pro-survival effect of statins in breast cancer patients, highlighting the clinical relevance of lowering cholesterol levels in breast cancer patients overexpressing ERRa.
... These particular NRs as thus referred to as "orphan" nuclear receptors. Falling within this category are the members of the Estrogen Related Receptor (ERR) subfamily, comprising three isoforms in mammals (ERRα, β and γ), that originate from distinct genes, ESRRA, ESRRB and ESRRG, respectively [1,2]. ...
... At least a number of their respective physiological and pathological functions have been determined, using various approaches including genetically modified animal models. ERRα and γ are highly involved in energy metabolism, bone homeostasis and cancer progression, amongst others (reviewed in [2][3][4][5][6]). Consistent with its expression pattern, the functions of ERRβ are more restricted, albeit not exclusively, to the maintenance of pluripotency in embryonic stem cells (ESC) in the mouse [7]. ...
Estrogen related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several tissues and cells and they display various physiological and pathological functions, controlling, amongst others and depending on the receptor, bone homeostasis, energy metabolism, embryonic stem cell pluripotency, and cancer progression. In contrast to classical nuclear receptors, the activities of the ERRs are not controlled by a natural ligand. Regulation of their activities thus rely on other means such as post-translational modification or availability of transcriptional co-regulators. In addition, regulation of their mere expression under given physiological or pathological conditions is a particularly important level of control. Here we discuss the mechanisms involved in the regulation of ERRs expression and the reported means to impact on it using pharmacological approaches.
... 51 ERRα is one of the most well-characterized transcription factors interacting with PGC-1α and probably acts as a surrogate ligand for ERRα. 52,53 In response to oncogenic signals, PGC-1α/ ERRα can be recruited to the promoter of genes involved in the TCA cycle and OXPHOS to initiate transcriptional programs, and this could favor pro-neoplastic outcomes. 47,[52][53][54] In mouse embryo fibroblasts (MEFs) expressing H-RasV, 12 ectopic PGC-1αwas reported to rescue ERRαexpression, increase OXPHOS capacity, and promote Ras-dependent anchorage-independent growth. ...
... 52,53 In response to oncogenic signals, PGC-1α/ ERRα can be recruited to the promoter of genes involved in the TCA cycle and OXPHOS to initiate transcriptional programs, and this could favor pro-neoplastic outcomes. 47,[52][53][54] In mouse embryo fibroblasts (MEFs) expressing H-RasV, 12 ectopic PGC-1αwas reported to rescue ERRαexpression, increase OXPHOS capacity, and promote Ras-dependent anchorage-independent growth. Moreover, the interaction with ERRα was required for PGC-1α to stimulate anchorage-independent growth. ...
Deregulation of cellular metabolism is well established in cancer. The mitochondria are dynamic organelles and act as the center stage for energy metabolism. Central to mitochondrial regulatory network is peroxisome proliferator‐activated receptor γ coactivator 1a (PGC‐1α), which serves as a master regulator of mitochondrial proliferation and metabolism. The activity and stability of PGC‐1α are subject to dynamic and versatile posttranslational modifications including phosphorylation, ubiquitination, methylation and acetylation in response to metabolic stress and other environmental signals. In this review, we describe the structure of PGC‐1α. Then, we discuss recent advances in the posttranslational regulatory machinery of PGC‐1α, which affects its transcriptional activity, stability and organelle localization. Furthermore, we address the important roles of PGC‐1α in tumorigenesis and malignancy. Finally, we also mention the clinical therapeutic potentials of PGC‐1α modulators. A better understanding of the elegant function of PGC‐1α in cancer progression could provide novel insights into therapeutic interventions through the targeting of PGC‐1α signaling.
... Estrogen-related receptors (ERRs; ERRα, ERRβ and ERRγ) comprise a subgroup of orphan nuclear receptors that share highly homologous DNA-binding domains with estrogen receptors. However, ERRs do not bind to endogenous estrogens or their derivatives, and thus are designated orphan receptors (10). High ERRγ expression levels are often associated with high metabolic demand in human tissues, such as skeletal muscle, heart and brown adipose tissue. ...
... Strict binding site specificity experiments indicated that the 3 members of ERRs preferentially recognize almost identical DNA elements, distinct from the traditional estrogen receptor element (ERE), referred to as the estrogen-related receptor response element (ERRE; TnAAGGTCA) (10). Subsequent studies identified widespread distribution of ERRγ targets, and transcriptionally active ERRγ forms a heterodimer or homodimer that binds to the promoter of target genes, while ligand is unnecessary for ERRγ activity (30,31). ...
S100 calcium binding protein A4 (S100A4) is a well‑established tumor metastasis mediator in various malignancies, including endometrial cancer (EC). However, the regulatory mechanism underlying S100A4 expression remains elusive. In the present study, by analyzing public datasets and clinical samples, we found that estrogen‑related receptor γ (ERRγ) was upregulated and positively correlated with S100A4 transcription in EC. ERRγ knockdown inhibited S100A4 expression and promoted the expression of its downstream target E‑cadherin, and vice versa. Mechanistic studies indicated that ERRγ enhanced the promoter activity of S100A4 to facilitate its transcription. In addition, knockdown of ERRγ suppressed migration and invasion of EC cells in vitro, while ectopic ERRγ expression promoted migration and invasion of EC cells in vitro and tumor growth in vivo. Importantly, restoration of S100A4 expression prevented EC cells from undergoing ERRγ‑mediated changes in these biological features. In addition, synchronous changes in S100A4 and ERRγ expression were observed after incubation with estrogen. Overall, ERRγ may exert oncogenic activity mainly associated with aggressiveness of EC by activating S100A4 transcription and thus may be a novel therapeutic target in EC.
... The most well-studied of these signaling pathways is the estrogen-related receptor α (ERRα) pathway [24]. ERRα is an orphan nuclear receptor that senses energy levels and promotes the expression of the genes involved in metabolic processes like β-oxidation, oxidative phosphorylation, the tricarboxylic acid cycle, and glycolysis when energy demand is high [25]. Like many other nuclear receptors, ERRα transcriptional activity depends on the presence of coregulators, particularly peroxisome proliferator-activated receptor-γ (PPARγ) coactivator 1 (PGC-1) [26]. ...
Cholesterol (CHOL) is a multifaceted lipid molecule. It is an essential structural component of cell membranes, where it cooperates in regulating the intracellular trafficking and signaling pathways. Additionally, it serves as a precursor for vital biomolecules, including steroid hormones, isoprenoids, vitamin D, and bile acids. Although CHOL is normally uptaken from the bloodstream, cells can synthesize it de novo in response to an increased requirement due to physiological tissue remodeling or abnormal proliferation, such as in cancer. Cumulating evidence indicated that increased CHOL biosynthesis is a common feature of breast cancer and is associated with the neoplastic transformation of normal mammary epithelial cells. After an overview of the multiple biological activities of CHOL and its derivatives, this review will address the impact of de novo CHOL production on the promotion of breast cancer with a focus on mammary stem cells. The review will also discuss the effect of de novo CHOL production on in situ and invasive carcinoma and its impact on the response to adjuvant treatment. Finally, the review will discuss the present and future therapeutic strategies to normalize CHOL biosynthesis.
... Estrogen related receptor α (ERRα) is one of the earliest identified orphan nuclear receptors, named for its similarity to human estrogen receptor α in DNA binding domain (Giguère et al. 1988). Previous studies have reported that ERRα is a key transcriptional regulator of energy metabolism, and involves in glucose and lipid metabolism, mitochondrial biogenesis and metabolic adaptation of various cells, tissues and organs (Deblois and Giguère 2011;Villena and Kralli 2008). The synergistic effect of ERRα and peroxisome proliferator-activated receptor-c coactivator 1α (PGC-1α) regulates the expression of mitochondrial related genes (such as cytochrome c, ATP synthase β and superoxide dismutase) and the production of reactive oxygen species (ROS) through targeting SIRT3 (Zhang et al. 2016). ...
Background
Sepsis-induced acute lung injury (ALI) is associated with poor survival rates. The identification of potential therapeutic targets for preventing sepsis-induced ALI has clinical importance. This study aims to investigate the role of estrogen-related receptor alpha (ERRα) in sepsis-induced ALI.
Methods
Lipopolysaccharide (LPS) was used to simulate sepsis-induced ALI model in rat pulmonary microvascular endothelial cells (PMVECs). The effects of ERRα overexpression and knockdown on LPS-induced endothelial permeability, apoptosis and autophagy were determined by horseradish peroxidase permeability assay, TdT-mediated dUTP Nick End Labeling (TUNEL) assay, flow cytometry, immunofluorescence staining, RT-PCR and Western Blotting. The rat model with sepsis-induced ALI was established by cecal ligation and puncture in anesthetized rats to verify the results of in vitro experiments. Animals were randomly assigned to receive intraperitoneal injection of vehicle or ERRα agonist. Lung vascular permeability, pathological injury, apoptosis and autophagy were examined.
Results
Overexpression of ERRα ameliorated LPS-induced endothelial hyperpermeability, degradation of adherens junctional molecules, upregulation of bax, cleaved caspase 3 and cleaved caspase 9 levels, downregulation of anti-apoptotic protein Bcl-2 level, and promoted the formation of autophagic flux, while the knockdown of ERRα exacerbated LPS-induced apoptosis and inhibited the activation of autophagy. Administration of ERRα agonist alleviated the pathological damage of lung tissue, increased the levels of tight junction proteins and adherens junction proteins, and decreased the expression of apoptosis-related proteins. Promoting the expression of ERRα significantly enhanced the process of autophagy and reduced CLP-induced ALI. Mechanistically, ERRα is essential to regulate the balance between autophagy and apoptosis to maintain the adherens junctional integrity.
Conclusion
ERRα protects against sepsis-induced ALI through ERRα-mediated apoptosis and autophagy. Activation of ERRα provides a new therapeutic opportunity to prevent sepsis-induced ALI.
... 190,191 The ERRs are orphan nuclear receptors that target the gene networks involved in energy homoeostasis, and in mitochondrial biogenesis and function. [192][193][194] Mitochondrial subdivision also involves the dynamin-like and the fis-type proteins. 41 Regulation of the numerical density of mitochondria in various cells: Metabolic needs may regulate the mitochondrial mass via-avis the cellular size across the cell cycle and the total body weight according to a power law. ...
Mitochondria are dynamic membrane-bound organelles in eukaryotic cells. These are important for the generation of chemical energy needed to power various cellular functions and also support metabolic, energetic, and epigenetic regulation in various cells. These organelles are also important for communication with the nucleus and other cellular structures, to maintain developmental sequences and somatic homeostasis, and for cellular adaptation to stress. Increasing information shows mitochondrial defects as an important cause of inherited disorders in different organ systems. In this article, we provide an extensive review of ontogeny, ultrastructural morphology, biogenesis, functional dynamics, important clinical manifestations of mitochondrial dysfunction, and possibilities for clinical intervention. We present information from our own clinical and laboratory research in conjunction with information collected from an extensive search in the databases PubMed, EMBASE, and Scopus.
... Moreover, the epidermal growth factor/Erb-B2 receptor tyrosine kinase 2 (EGF/ERBB2) signaling pathway in breast cancer cells modulated the transcription activity of ESRRA, which was associated with poor prognosis in breast and ovarian cancers 32,34,35 . Implanted xenografts with knockdown of ESRRA expression in MDA-MB-231 cells can reduce the tumor growth rate of breast cancers 36 . In the present study, we found prominent expression of FKBP4 and ESRRA in LOM and LOSCC, possibly being novel prognostic biomarkers and therapeutic target candidates. ...
Tumors frequently found in dogs include canine oral tumors, either cancerous or noncancerous. The bloodstream is an important route for tumor metastasis, particularly for late-stage oral melanoma (LOM) and late-stage oral squamous cell carcinoma (LOSCC). The present study aimed to investigate serum peptidome-based biomarkers of dogs with early-stage oral melanoma, LOM, LOSCC, benign oral tumors, chronic periodontitis and healthy controls, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography tandem mass spectrometry. A principal component analysis plot showed distinct clusters among all groups. Four peptides were identified, including peptidyl-prolyl cis-trans isomerase FKBP4 isoform X2 (FKBP4), steroid hormone receptor ERR1 (ESRRA or ERRA), immunoglobulin superfamily member 10 (IGSF10) and ATP-binding cassette subfamily B member 5 (ABCB5). FKBP4, ESRRA and ABCB5 were found to be overexpressed in both LOM and LOSCC, whereas IGSF10 expression was markedly increased in LOSCC only. These four proteins also played a crucial role in numerous pathways of cancer metastasis and showed a strong relationship with chemotherapy drugs. In conclusion, this study showed rapid screening of canine oral tumors using serum and MALDI-TOF MS. In addition, potential serum peptidome-based biomarker candidates for LOM and LOSCC were identified.
... Estrogen related receptor α (ERRα) is one of the earliest identi ed orphan nuclear receptors, named for its similarity to human estrogen receptor α in DNA binding domain (Giguère et al., 1988). A large number of studies have reported that ERRα is a key transcriptional regulator of energy metabolism, and involves in glucose and lipid metabolism, mitochondrial biogenesis and metabolic adaptation of various cells, tissues and organs (Deblois and Giguère, 2011;Villena and Kralli, 2008). The synergistic effect of ERRα and peroxisome proliferator-activated receptor-c coactivator 1α (PGC-1α) regulates the expression of mitochondrial related genes (such as cytochrome c, ATP synthase β and superoxide dismutase) and the production of reactive oxygen species (ROS) through targeting SIRT3 (Zhang et al., 2016). ...
Sepsis-induced acute lung injury (ALI) is associated with poor survival rates. The identification of potential therapeutic targets for preventing sepsis-induced ALI has clinical importance. Here, we show that estrogen-related receptor alpha (ERRα) protects against sepsis-induced ALI through ERRα-mediated apoptosis and autophagy. ERRα was upregulated in inflammation models from lipopolysaccharides (LPS)-treated rat pulmonary microvascular endothelial cells (PMVECs) and cecal ligation and puncture (CLP)-induced septic rats. In vitro , overexpression of ERRα ameliorated LPS-induced degradation of adherens junctional molecules, upregulation of bax, cleaved caspase 3 and cleaved caspase 9 levels and downregulation of anti-apoptotic protein Bcl-2 level, and promoted the formation of autophagic flux, while the knockdown of ERRα exacerbated LPS-induced apoptosis and inhibited the activation of autophagy. Rats injected with ERRα agonist were subjected to CLP to elucidate the role of ERRα in sepsis-induced ALI in vivo . Administration of ERRα agonist alleviated the pathological damage of lung tissue, increased the levels of tight junction proteins and adherens junction proteins, and decreased the expression of apoptosis-related proteins. Promoting the expression of ERRα significantly enhanced the process of autophagy and reduced CLP-induced ALI. Mechanistically, ERRα is essential to regulate the balance between autophagy and apoptosis to maintain the adherens junctional integrity. These findings indicate that activation of ERRα provides a new therapeutic opportunity to prevent sepsis-induced ALI.
... A unique feature of ERRα is its partnership with the co-activator peroxisome proliferatoractivated receptor γ coactivator 1α (PGC-1α). When paired together, the PGC/ERR axis activity is increased and influences many oncogenic signals as well as regulates the transcription of certain metabolic genes [9][10][11][12]. In ERR −/− mice on a high-fat diet, there is a resistance to obesity implying an important role [13]. ...
The estrogen-related receptor alpha (ERRα, NR3B1) is an orphan nuclear receptor which plays a role in endocrine disruption, energy homeostasis, and cancer prognosis. One of the unique features of this transcription factor is the interplay with its cofactors. For instance, certain modulators require the presence of proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) alongside ERRα. Therefore, identification of ERRα agonists and antagonists require examination of this nuclear receptor alone and together with PGC-1α. In this book chapter, we describe the step-by-step protocol of a multiplex luciferase assay designed to identify ERRα agonists, antagonists, and toxicity in one quantitative high-throughput screening assay using two different stable cell lines.
... estrogen-related receptor-α (errα) is a member of the orphan nuclear receptors (9) and belongs to the err family, which consists of errα, errβ and errγ (10). errα was identified on the basis of the structural similarity between its dna binding domain and human estrogen receptor (er) α; however, errα does not bind to natural estrogens or estrogen-like molecules (11). ...
The nuclear estrogen‑related receptor‑α (ERRα) is an orphan receptor that has been identified as a transcriptional factor. Peroxisome proliferator‑activated receptor‑γ (PPARγ) coactivator‑1‑α (PGC‑1α) and PPARγ coactivator‑1‑β (PGC‑1β) act as the co‑activators of ERRα. Our previous study reported that activated ERRα promoted the invasion and proliferation of gallbladder cancer cells by promoting PI3K/AKT phosphorylation. Therefore, the aim of the current study was to investigate whether PI3K/AKT phosphorylation could enhance ERRα activity in a positive feedback loop. LY294002 and insulin‑like growth factor I (IGF‑I) were used to inhibit and promote PI3K/AKT phosphorylation, respectively. A 3X ERE‑TATA luciferase reporter was used to measure ERRα activity. The present study found that LY294002 inhibited PI3K/AKT phosphorylation, decreased the proliferation and invasion of NOZ cells and suppressed the activity of ERRα. Conversely, IGF‑I induced PI3K/AKT phosphorylation, promoted the proliferation and invasion of NOZ cells and enhanced the activity of ERRα. The protein expression levels of PGC‑1α and PGC‑1β were elevated and reduced by IGF‑I and LY294002, respectively. Moreover, knockdown of PGC‑1α and PGC‑1β antagonized ERRα activation, which was enhanced by PI3K/AKT phosphorylation. Taken together, the present study demonstrated that PI3K/AKT phosphorylation triggered ERRα by upregulating the expression levels of PGC‑1α and PGC‑1β in NOZ cells.
... High expression of ERRα to meet the requirements for the base energy is unnecessary. But, its presence to provide high levels of energy in response to events like training stimuli is required [35]. In the present study, the exercise training intensity (27 m/min) was equivalent to 75% of the maximum oxygen consumption that increases skeletal muscle energy consumption five times over resting values [36]. ...
AimsThe aim of present study was to investigate the effect of endurance training and ERRα inhibition (target for the discovery of new therapies for diseases such as diabetes) on the gene and protein expression of factors involved in lipid metabolism in diabetic rats.Methods
We designed the current study to evaluate the combination of ERRα inhibition and exercise training effects on the expression of ERRα, medium-chain acyl-CoA dehydrogenase (MCAD), carnitine palmitoyltransferase-1b (CPT-1b), pyruvate dehydrogenase kinase 4 (PDK4) and Citrate synthase (CS) in diabetic and non-diabetic rats. Sixty-four male Wistar rats were divided into 8 groups (n = 8) as follows: non-diabetic control, diabetic control (a single dose of 45 mg/kg of STZ), non-diabetic/ERRα inhibition group (received 0.48 mg/kg of XCT790), diabetic/ERRα inhibition group, non-diabetic/exercise training, diabetic/exercise training, non-diabetic rats which received XCT790 and performed exercise training, and diabetic rats which received XCT790 and also performed exercise training. The gene and protein expression were measured by real-time PCR (quantified by \( 2^{{ - \Delta \Delta CT }}\) method) and Western blotting method, respectively.ResultsOur results showed that the expression of ERRα (1.6-fold), MCAD (4.6-fold), CPT-1b (fivefold), CS (twofold), PDK4 (fourfold), and PGC-1α (fourfold) in the medial gastrocnemius muscle of the non-diabetic exercise training group was significantly higher than the non-diabetic control group.Conclusion
In sum, ERRα is a trainable factor, and its changes are parallel with higher expression of the enzymes which involved in lipid metabolism in healthy rats. ERRα inhibition and endurance training may have positive effects on the lipid metabolism in diabetic rats. This indirectly suggests a significant role of ERRα in the adaptation of lipid metabolism evoked by endurance training.
... The PGC-1α/ERRα axis also has been implicated in regulating several genes involved in energy metabolism, and increased mRNA and protein levels of ERRα in tissues are accompanied by high expression of PGC-1α. 26,27 Expression of PGC-1α and ERRα is sensitive to physiological and pathological changes, which strengthens their crucial role in energy homeostasis in health and disease. 9 Compounds affecting either the coactivator or the receptor could regulate signaling activity. ...
Purpose:
Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and estrogen-related receptor alpha (ERRα) play a vital role in various human cancers. The purpose of this study was to investigate whether the PGC-1α/ERRα axis could serve as an effective prognostic marker in ovarian cancer (OC).
Patients and methods:
We investigated the expression of both PGC-1α and ERRα in 42 ovarian cancer and 31 noncancerous ovarian samples by immunohistochemistry (IHC). The relationship between the expression of PGC-1α and ERRα in OC and the clinical characteristics of patients was evaluated. In addition, data from the Human Protein Atlas (HPA) database were collected to validate the prognostic significance of PGC-1α and ERRα mRNA expression in OC.
Results:
PGC-1α and ERRα showed notably higher expression in OC tissues than in noncancerous tissues (P=0.0059, P=0.002). Moreover, in patients with OC, high ERRα and PGC-1α/ERRα expression significantly correlated with tumor differentiation (P=0.027; P=0.04), lymph node status (P=0.023; P=0.021), CA125 (P=0.036; P=0.021), and HE4 (P=0.021; P=0.05), while high PGC-1α expression was only significantly associated with tumor differentiation (P=0.029). The combined analysis of high PGC-1α and ERRα expression revealed a tendency towards poor cancer-specific survival (P=0.1276).
Conclusion:
PGC-1α and ERRα are overexpressed in OC and might be significant prognostic factors for this cancer.
... Estrogen-related receptors (ERRs), including the α, β and γ subtypes (ERRα, ERRβ and ERRγ), are members of the nuclear receptor family that are involved in many biological processes [1,2]. Despite their overall sequence and structure similarity with the estrogen receptors (ERs), ERRs exhibit the constitutive transcriptional activity in a ligandindependent manner, which is different from the activation of ERs by estrogens [3,4]. ...
Estrogen-related receptor β (ERRβ) is a nuclear receptor critical for many biological processes. Despite the biological and pharmaceutical importance of ERRβ, deciphering the structure of ERRβ have been hampered by the difficulties in obtaining a pure and stable protein for structural studies. In fact, the ERRβ ligand binding domain (LBD) remains the last unsolved ERR structure and also one of only a few unknown nuclear receptor structures. Here, we report the identification of a critical single residue mutation resulted in robust solubility and stability of an active ERRβ LBD, thereby providing a protein tool enabling the first probe into the biochemical and structural studies of this important receptor. The crystal structure reveals key structural features that have enabled the integration of the molecular determinants of signals transduced across the ligand binding and coregulator recruitment by all three ERR subtypes, which also provides a framework for the rational design of selective and potent ligands for the treatment of various ERR-mediated diseases.
... There are many receptors involved in the immunity response, for example, ERs, which are closely related to the such system since it has been shown their influence to mediate their response. Likewise, BPA can bind to other receptors relevant in the immune system response such as aryl-hydrocarbon receptor (AhR), Toll-like receptors (TLRs) and peroxisome proliferator-activated receptor (PPAR) affecting, directly and indirectly, the response (63)(64)(65)(66). ...
Evaluation of carcinogenic substances from the environment is a challenge for scientists. Recently, a novel approach based on 10 key characteristics of human carcinogens classified by the International Agency for Research on Cancer (IARC) has emerged. Carcinogenesis depends on different mechanisms and factors, including genetic, infectious (bacteria, viruses) and environmental (chemicals) factors. Endocrine disruptors are exogenous chemicals that can interfere and impair the function of the endocrine system due to their interaction with estrogen receptors or their estrogen signaling pathways inducing adverse effects in the normal mammary development, originating cancer. They are heterogeneous chemicals and include numerous synthetic substances used worldwide in agriculture, industry and consumer products. The most common are plasticizers, such as bisphenol A (BPA), pesticides, such as dichlorodiphenyltrichloroethane, and polychlorinated biphenyls (PCBs). Xenoestrogens appear to serve an important role in the increased incidence of breast cancer in the United States and numerous other countries. Several studies have demonstrated the role of organochlorine xenoestrogens in breast cancer. Therefore, the overall cumulative exposure of women to estrogens results in an increased risk for this type of cancer. Factors like lifestyle and diet also serve a role in the increased incidence of this disease. The aim of the present study was to analyze these chemical compounds based on the key characteristics given by the IARC, with a special focus on breast cancer, to establish whether these compounds are carcinogens, and to create a model for future analysis of other endocrine disruptors.
... However, subsequent ligand binding and reporter-gene transfection studies surprisingly demonstrated that estrogens did not bind to ESRRs with a high affinity, and did not directly regulate their expression and/or transcriptional activity. Thus far, with the possible exception of cholesterol, there have not been any endogenous ligands identified for ESRRA; hence, it is still considered an "orphan" nuclear receptor that does not have a bona fide endogenous ligand [1,4,5]. ESRRs belong to a small subfamily of nuclear receptors called NR3B and consisting of three members: estrogen-related receptor alpha (ESRRA/NR3B1), beta (ESRRB/NR3B2), and gamma (ESRRG/NR3B3) [6][7][8][9]. ...
The estrogen-related receptor alpha (ESRRA) is an orphan nuclear receptor (NR) that significantly influences cellular metabolism. ESRRA is predominantly expressed in metabolically-active tissues and regulates the transcription of metabolic genes, including those involved in mitochondrial turnover and autophagy. Although ESRRA activity is well-characterized in several types of cancer, recent reports suggest that it also has an important role in metabolic diseases. This minireview focuses on the regulation of cellular metabolism and function by ESRRA and its potential as a target for the treatment of metabolic disorders.
... Estrogen-related receptor a (ERRa and NR3B1(ESRRA)) is an orphan nuclear hormone receptor capable of regulating transcription of genes involved in multiple cellular and physiological processes [19]. The best characterized of these is its role in energy metabolism in which ERRa is co-activated by PGC-1a to regulate genes required for mitochondrial function [20]. ...
Aging deteriorates osteogenic capacity of mesenchymal stem/stromal cells (MSCs), contributing to imbalanced bone remodeling and osteoporosis. Glutaminase (Gls) catabolizes glutamine into glutamate at the first step of mitochondrial glutamine (Gln)-dependent anaplerosis which is essential for MSCs upon osteogenic differentiation. Estrogen-related receptor a (ERRa) regulates genes required for mitochondrial function. Here, we found that ERRa and Gls are upregulated by osteogenic induction in human MSCs (hMSCs). In contrast, osteogenic differentiation capacity and glutamine consumption of MSCs, as well as ERRa, Gls and osteogenic marker genes are significantly reduced with age.
... growth, development, and differentiation of various target tissues. With the study of estrogen action, it has been shown that estrogen not only plays a role in target tissues, but also exerts extensive biological effects on non-target tissues in women, such as musculoskeletal, cardiovascular, central nervous, and immune system [5,6]. Clinical investigations have found that the incidence of osteoporosis was significantly higher in menopausal and postmenopausal women than in men of the same age [7,8]. ...
Background and AimsIntestinal calcium absorption from the diet plays important role in maintaining calcium homeostasis in the body. Estrogen exerts wide physiological and pathological effects in the human. Previous studies have shown that estrogen is involved in the intestinal calcium absorption. In this study, we made investigation on the mechanism of estrogen action on duodenal calcium absorption.Methods
The experiments were performed in mice, human, and human duodenal epithelial cells, SCBN cells. Murine duodenal calcium absorption was measured by using single pass perfusion of the duodenum in vivo. The calcium absorption of SCBN cells was evaluated by calcium imaging system. The expression of calcium transport proteins, transient receptor potential cation channel (TRPV6) and plasma membrane calcium pump (PMCA1b), in the duodenum or SCBN cells were analyzed by western blot.ResultsThe duodenal calcium absorption in ovariectomized mice was significantly decreased, compared with control female mice, which returned to control level after 17β-estradiol replacement treatment. Estrogen regulated the expressions of TRPV6 and PMCA1b in murine and human duodenal mucosae and SCBN cells. The further results from SCBN cells showed that 17β-estradiol regulated calcium influx through the respective effects of estrogen receptor (ER) ɑ and β on TRPV6 and PMCA1b.Conclusion
Estrogen regulates duodenal calcium absorption through differential role of ERɑ and ERβ on duodenal epithelial cellular TRPV6 and PMCA1b. The study further elucidates the mechanism of estrogen on the regulation of intestinal calcium absorption.
... For example, quantitative proteomics studies of breast cancer cells revealed that key mitochondrial-related proteins involving in fatty acid β-oxidation and ketone metabolism as well as mitochondrial biogenesis were significantly upregulated in the mammospheres relative to the epithelial monolayers, suggesting that clonal expansion of BCSCs requires mitochondrial OXPHOS [77]. Indeed, XCT790, a well-established inhibitor of estrogen-related receptor a (ERRa), which functions as an essential cofactor of PGC-1α required for mitochondrial biogenesis [78,79], suppresses BCSC activity by blocking several independent signaling pathways normally required for the self-renewal of CSCs, including Sonic hedgehog, TGFβ-SMAD, STAT3 and Wnt signaling [80]. This PGC-1α mediated mitochondrial biogenesis and OXPHOS is essential for the functional motility of breast cancer cells and metastasis [81]. ...
Cancer has long been viewed as a disease of altered metabolism. Although it has long been recognized that the majority of cancer cells display increased dependence on glycolysis, the metabolism of "cancer stem-like cells" (CSCs) that drive tumor growth and metastasis is less well characterized. In this chapter, we review the current state of knowledge of CSC metabolism with an emphasis on the development of therapeutic strategies to exploit the metabolic vulnerabilities of these cells. We outline emerging evidence indicating distinct metabolic pathways active in the proliferative, epithelial- (E) and quiescent, mesenchymal-like (M) CSC states in triple negative breast cancer. These CSC states are characterized by their different redox potentials and divergent sensitivities to inhibitors of glycolysis and redox metabolism. We highlight the roles of two redox-regulated signaling pathways, hypoxia-inducible factor 1α and nuclear factor erythroid 2-related factor 2, in regulating CSC epithelial-mesenchymal plasticity during metabolic and/or oxidative stress, and discuss clinical strategies using combinations of pro-oxidant-based therapeutics simultaneously targeting E- and M-like CSCs. By specifically targeting CSCs of both states, these strategies have the potential to increase the therapeutic efficacy of traditional chemotherapy and radiation therapy.
... ERRs are a small group of orphan nuclear receptor transcription factors with 3 isoforms, namely ERRα (NR3B1), ERRβ (NR3B2) and ERRγ (NR3B3) (6)(7)(8)(9). The 3 mammalian ERR genes have been implicated in diverse physiological processes, ranging from placental development to bone density maintenance (10,11). ...
Estrogen-related receptor γ (ERRγ) is a member of a small group of orphan nuclear receptor transcription factors that have been implicated in several physiological and pathological processes, including placental development, regulation of metabolic genes or disease. The pattern of expression of ERRγ, its role in neuronal injury and its co-localization with other transcription factors in the spinal cord of rats with brachial plexus injury has not been determined. The expression profile of ERRγ and its co-localization with RNA binding protein fox-1 homolog 3 (NeuN) or cyclic AMP-dependent transcription factor 3 (ATF-3) in the motor neurons of rats that underwent brachial plexus root avulsion were assessed using western blot analysis, immunohistochemistry and immunofluorescence. Fluorogold (FG) was used to mark neurons whose axons were severed. ATF-3 was expressed in the nuclei of motor neurons whose axons were severed by root avulsion. On day 3 post-avulsion, FG and ATF-3 were all co-localized in the injured motor neurons. The level of ERRγ protein in the ipsilateral half of injured spinal cords was significantly decreased compared with that in the contralateral half on days 3, 14 and 28 post-avulsion (all P<0.05). The numbers of ERRγ-positive motor neurons (ERRγon) were also notably decreased in the ipsilateral side compared with that in the contralateral side on days 14 and 28 post-avulsion, implying that the expression occurred in α motor neurons that were progressively being lost, a phenomenon that was expected post-brachial plexus avulsion. Almost all large and small ERRγ-positive motor neurons were also NeuN-positive (NeuNon). However, a few of these were ERRγon/NeuNoff (no NeuN signal). Therefore, these results suggested that ERRγ is a non-specific marker of γ motor neurons in rats, and therefore, this specific transcriptional program cannot be used to define functionally distinct motor neuron sub-populations. However, its downregulation on the injured side suggests that it is an important component of the response to injury in motor neurons.
... ERRα and ERRγ regulate the transcription of genes involved in mitochondrial biogenesis, oxidative phosphorylation, tricarboxylic acid (TCA) cycle, fatty acid oxidation and glucose metabolism 28, [36][37][38][39][40][41][42][43][44][45][46] . However, in addition to overlapping gene activation there is also ample evidence that ERRα and ERRγ also have differential and opposing effects which can be due to interactions with corepressors, coactivators, posttranslational modification, or differential cell expression 28, 46 . ...
Background
A gradual decline in renal function occurs even in healthy aging individuals. In addition to aging per se , concurrent metabolic syndrome and hypertension, which are common in the aging population, can induce mitochondrial dysfunction and inflammation, which collectively contribute to age-related kidney dysfunction and disease. Here we studied the role of the nuclear hormone receptors, the estrogen-related receptors (ERRs) in regulation of age-related mitochondrial dysfunction and inflammation. ERRs were decreased in aging human and mouse kidneys and were preserved in aging mice with lifelong caloric restriction (CR).
Methods
A pan-ERR agonist was used to treat 21-month-old mice for 8-weeks. In addition, 21-month-old mice were treated with a STING inhibitor for 3 weeks.
Results
Remarkably, only an 8-week treatment with a pan-ERR agonist reversed the age-related increases in albuminuria, podocyte loss, mitochondrial dysfunction and inflammatory cytokines, including the cGAS-STING and STAT3 signaling pathways. A 3-week treatment of 21-month-old mice with a STING inhibitor reversed the increases in inflammatory cytokines and the senescence marker p21 but also unexpectedly reversed the age-related decreases in PGC-1α, ERRα, mitochondrial complexes and MCAD expression.
Conclusions
Our studies identified ERRs as important modulators of age-related mitochondrial dysfunction and inflammation. These findings highlight novel druggable pathways that can be further evaluated to prevent progression of age-related kidney disease.
Significance Statement
There is an increasing need for prevention and treatment strategies for age-related kidney disease. The hallmarks of aging kidneys are decreased mitochondrial function and increased inflammation. The expression of the nuclear hormone receptors estrogen-related receptors (ERRs) are decreased in aging human and mouse kidneys. This paper investigates the role of ERRs in the aging kidney. Treatment of aging mice with a pan-ERR agonist reversed the age-related increases in albuminuria and podocyte loss, mitochondrial dysfunction and inflammatory cytokines, including the cGAS-STING signaling pathways. Treatment of aging mice with a STING inhibitor decreased inflammation and increased mitochondrial gene expression. These findings identify ERRs as important modulators of age-related mitochondrial dysfunction and inflammation.
... Functional genomic studies have identified ERRα as a comprehensive and genuine master regulator of the nuclear-encoded mitochondrial transcriptome. ERRα exerts its regulatory function via occupying the promoter regions of more than 700 genes encoding mitochondrial proteins, which are involved in all aspects of mitochondrial biogenesis and function (11,120). No other transcription factor has been shown to control mitochondrial physiology and function as extensively. ...
As transcriptional factors, nuclear receptors (NRs) function as major regulators of gene expression. In particular, dysregulation of NR activity has been shown to significantly alter metabolic homeostasis in various contexts leading to metabolic disorders and cancers. The orphan estrogen-related receptor (ERR) subfamily of NRs, comprised of ERRα, ERRβ, and ERRγ, for which a natural ligand has yet to be identified, are known as central regulators of energy metabolism. If AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) can be viewed as sensors of the metabolic needs of a cell and responding acutely via post-translational control of proteins, then the ERRs can be regarded as downstream effectors of metabolism via transcriptional regulation of genes for a long-term and sustained adaptive response. In this review, we will focus on recent findings centered on the transcriptional roles played by ERRα in hepatocytes. Modulation of ERRα activity in both in vitro and in vivo models via genetic or pharmacological manipulation coupled with chromatin-immunoprecipitation (ChIP)-on-chip and ChIP-sequencing (ChIP-seq) studies have been fundamental in delineating the direct roles of ERRα in the control of hepatic gene expression. These studies have identified crucial roles for ERRα in lipid and carbohydrate metabolism as well as in mitochondrial function under both physiological and pathological conditions. The regulation of ERRα expression and activity via ligand-independent modes of action including coregulator binding, post-translational modifications (PTMs) and control of protein stability will be discussed in the context that may serve as valuable tools to modulate ERRα function as new therapeutic avenues for the treatment of hepatic metabolic dysfunction and related diseases.
... However, our results show that AMF may affect EC growth through GPER-1 both in the estrogen-dependent endometrial cancer cell line Ishikawa and the non-estrogen-dependent endometrial cancer cell line SPEC-2. Therefore, similar to the redundant functions of ERa and ERβ in PI3K pathway associated with sperm survival [34], and the redundant functions of estrogen-related receptors ERRγ and ERRβ in promoting reprogramming of mouse fibroblasts [35], it is possible that estrogen and AMF do not compete for specific receptors, but instead function redundantly during EC tumorigenesis and progression. The activation of GPER-1 downstream pathways is coupled with EGFR transactivation via Src-mediated metal-loproteinases upregulation, which driving the release of HB-EGF and eventually activating EGFR [6]. ...
Background
Autocrine motility factor (AMF) is a critical factor regulating aggressiveness of endometrial cancer (EC). Multiple pieces of evidence indicate that it is through G protein coupled estrogen receptor (GPER) signaling pathway that some growth factors promoted the migration and proliferation of tumor cells. The aim of this study is to explore the role of GPER-1 in AMF mediated regulatory mechanisms of EC recurrence and progression.
Methods
Real-Time Cell Analysis (RTCA) assays were performed to assess whether AMF depends on Autocrine motility factor recepter (AMFR) signaling in EC cells. A genome-wide expression microarray and Yeast Two-Hybrid assay were used to detect AMF and GPER-1 interaction in the context of AMFR depletion, and co-immunoprecipitation and immunofluorescence experiments were performed to confirm the physical interaction. Isobaric Tags for Relative and Absolute Quantification (iTRAQ) analysis was used for the identification of the target pathway activated by AMF-GPER-1 interaction. Cohorts of mice harboring xenografts derived from modified SPEC2 cell lines were treated with or without exogenous AMF to validate the results of previous experiments. Immunohistochemistry was performed to assess AMF and GPER-1 expression in endometrial cancer specimens and normal endometrium.
Results
Our data showed that GPER-1 binds to AMF and the formed complex translocates from the plasma membrane to the cytoplasm. Mechanistic investigations demonstrated that interaction between AMF and GPER-1 triggers phosphoinositide-3-kinase signaling and promotes EC cell growth. More importantly, through animal experiments and human tissue experiments, we found that AMF contributes to GPER-1-mediated EC progression, which is consistent with the above observations.
Conclusions
Our work not only delineated the regulatory mechanisms of endometrial cancer progression by AMF-GPER-1-AKT signaling cascade but also laid the foundation of targeting this pathway for treating endometrial cancer.
Electronic supplementary material
The online version of this article (10.1186/s12964-019-0336-4) contains supplementary material, which is available to authorized users.
... When ERRα is paired with a co-activator, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a master regulator in energy homeostasis, its activity is greatly enhanced [23,24]. The PGC/ERR axis is not only regulating transcriptional activity of the metabolic gene network [25,26], but also influencing oncogenic signals that induce cell growth, proliferation, invasion, angiogenesis, and vascularization as demonstrated in a series of studies on the expression of vascular endothelial growth factor (VEGF) [27][28][29], hypoxia-inducible factor (HIF) [27,30,31], interleukin-6 (Il6) [32], and WNT11 [33,34]. Therefore, modulation of ERRα function may present a valuable therapeutic target to consider in developing novel drugs to treat cancer or diseases associated with metabolic disruptions. ...
The nuclear receptor, estrogen-related receptor alpha (ERRα; NR3B1), plays a pivotal role in energy homeostasis. Its expression fluctuates with the demands of energy production in various tissues. When paired with the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), the PGC/ERR pathway regulates a host of genes that participate in metabolic signaling networks and in mitochondrial oxidative respiration. Unregulated overexpression of ERRα is found in many cancer cells, implicating a role in cancer progression and other metabolism-related diseases. Using high throughput screening assays, we screened the Tox21 10K compound library in stably transfected HEK293 cells containing either the ERRα-reporter or the reporter plus PGC-1α expression plasmid. We identified two groups of antagonists that were potent inhibitors of ERRα activity and/or the PGC/ERR pathway: nine antineoplastic agents and thirteen pesticides. Results were confirmed using gene expression studies. These findings suggest a novel mechanism of action on bioenergetics for five of the nine antineoplastic drugs. Nine of the thirteen pesticides, which have not been investigated previously for ERRα disrupting activity, were classified as such. In conclusion, we demonstrated that high-throughput screening assays can be used to reveal new biological properties of therapeutic and environmental chemicals, broadening our understanding of their modes of action.
... The crucial role of mitochondria in CSCs impelled several groups to develop therapeutic strategies aimed at their targeting (Skoda et al., 2018). Notably, mitochondrial biogenesis can be abrogated through the estrogen-related receptor α inhibitor XCT790 (Deblois and Giguere, 2011;Deblois et al., 2013), whereas their fission can be impaired thanks to the dynamin-related protein 1 (DRP1) inhibitors Mdivi-1 and P110 (Xie et al., 2015). In addition, it has been demonstrated that DRP1 activation may be promoted by the interaction between cyclooxygenase-2 (COX-2) and mitochondria. ...
Notwithstanding cancer patients benefit from a plethora of therapeutic alternatives, drug resistance remains a critical hurdle. Indeed, the high mortality rate is associated with metastatic disease, which is mostly incurable due to the refractoriness of metastatic cells to current treatments. Increasing data demonstrate that tumors contain a small subpopulation of cancer stem cells (CSCs) able to establish primary tumor and metastasis. CSCs are endowed with multiple treatment resistance capabilities comprising a highly efficient DNA damage repair machinery, the activation of survival pathways, enhanced cellular plasticity, immune evasion and the adaptation to a hostile microenvironment. Due to the presence of distinct cell populations within a tumor, cancer research has to face the major challenge of targeting the intra-tumoral as well as inter-tumoral heterogeneity. Thus, targeting molecular drivers operating in CSCs, in combination with standard treatments, may improve cancer patients’ outcomes, yielding long-lasting responses. Here, we report a comprehensive overview on the most significant therapeutic advances that have changed the known paradigms of cancer treatment with a particular emphasis on newly developed compounds that selectively affect the CSC population. Specifically, we are focusing on innovative therapeutic approaches including differentiation therapy, anti-angiogenic compounds, immunotherapy and inhibition of epigenetic enzymes and microenvironmental cues.
... But, some time the unwanted level of E2 has been reported to be carcinogenic. The mechanisms involved in carcinogenic effects of estradiol are stimulation of cell proliferation and differentiation via estrogen receptor (ER)-mediated pathway [13,14]. ROS generation during a cytochrome P450 (CYP)-mediated estrogen metabolism leads to genotoxic effects like mutation and chromosome abnormalities, and may also regulate enzyme activity or transcription factors through redox regulation [15,16]. ...
N-ethyl-N-nitrosourea (ENU) is highly used in rodent models of tumerogenesis/carcinogenesis. Xenografting human-cancer tissues/cells with estradiol (E2) treatment is also used to generate rodent-models of gynaecological cancers. The altered metabolic-redox environment leading to establishment of pre-tumorigenesis condition and their mechanism are less studied. Here, female Wister rats were treated with these drugs at their pre-tumerogenic dosage (one group ENU single intra-peritoneal dose of 90 mg/kg b.w. and another group were implanted with human breast tumor (stage-IIIB) and fed with 2.5 mg of 17β-estradiol once in a week for 4 months). After 4 months, animals were sacrificed; their serum and liver tissues were tested. A brief comparison was made with a rat model (regarded as positive control) of toxicity induced by mutagenic environmental pollutant arsenic (0.6 ppm daily/4 weeks). The increase in serum alkaline phosphatase and glutamate-pyruvate transaminase suggests the possible organ toxicity is favoured by the increase in hepatic/systemic free radicals and oxidative stress in all drug application models. But the increase in the serum E2 level as noted in the ELISA data with impairment in the hepatic estrogen sulfotransferase (SULT1E1) protein expression (immuno-blot data) were noticed with interfered hepatic free-thiols only in ENU and xenograft-E2 group compared to arsenic group. It is also evident in the in vitro result from E2/GSH/NAC added hepatic slices with altered antioxidant regulations. Moreover, impairment in hepatic SOD1, catalase and glutathiole peroxidase activities (PAGEzymographic data), especially in the ENU-treated group makes them more vulnerable to the oxidative threat in creating pre-tumerogenic microenvironment. This is evident in the result of their higher DNA-damage and histological abnormalities. The Bioinformatics study revealed an important role of rSULT1E1 in the regulations of E2 metabolism. This study is important for the exploration of the pre-tumerogenic condition by ENU and E2 by impairing SULT1E1 expression and E2 regulations via oxidant-stress signalling. The finding may help to find new therapeutic-targets to treat gynaecological-cancers more effectively.
... Estrogen related receptor α (ERRα) is an orphan nuclear receptor and regulates energy metabolism and mitochondrial biogenesis [24,25]. ERRα and its co-activator PGC-1α work with each other to affect the transcription of target genes [16,17]. ...
Background/aims:
Although a number of reports documented the important role of parkin in mitophagy, emerging evidence also indicated additional functions of parkin besides mitophagy. The present study was undertaken to investigate the role of parkin in the regulation of ERRα/eNOS pathway in endothelial cells (ECs).
Methods:
Mouse aortic endothelial cells (MAECs) and cardiac muscle HL-1 cells were transfected with parkin plasmid or siRNA. ERRα inhibitor XCT-790, autophagy inhibitor 3-MA and Bafilomycin A1, and caspase inhibitor Z-VAD-FMK were used to block autophagy or apoptosis. Western blotting was performed to examine the protein levels. Flow cytometry was applied to determine the cell apoptosis and ROS production. Mitochondrial membrane potential was measured using JC-1 and TMRM. Immunoprecipitation was performed to confirm the parkin effect on ERRα ubiquitination.
Results:
Overexpression of parkin resulted in a significant reduction of total-eNOS and p-eNOS in parallel with the downregulation of ERRα (a regulator of eNOS) protein and the enhancement of ERRα ubiquitination. To test the role of ERRα in regulating eNOS in this experimental setting, we treated ECs with ERRα inhibitor and found a decrement of total-eNOS and p-eNOS. On the contrary, overexpression of ERRα increased the levels of total-eNOS and p-eNOS. Meanwhile, parkin overexpression induced mitochondrial dysfunction and cell apoptosis in both ECs and HL-1 cells. Finally, we confirmed that the parkin effect on the regulation of eNOS was independent of the autophagy and apoptosis.
Conclusion:
These findings suggested that parkin overexpression downregulated eNOS possibly through the ubiquitination of ERRα in endothelial cells.
... In fact, ablation of either ERRα or β-catenin expression decreases the migratory ability of different types of cancer cells. In addition, functional genomic studies have identified further ERRα target genes playing an important role in the process of invasion, migration and tumor vascularization (27). ...
The estrogen-related receptors (ERRs) are important members of nuclear receptors which contain three isoforms (α, β, and γ). ERRα is the best-characterized isoform expressed mainly in high-energy demanding tissues where it preferentially works in association with the peroxisome proliferator-activated receptor-γ co-activator 1α (PGC-1α) and PGC-1β. ERRα together with its cofactors modulates cellular metabolism, supports the growth of rapidly dividing cells, directs metabolic programs required for cell differentiation and maintains cellular energy homeostasis in differentiated cells. In cancer cells, the functional association between ERRα and PGC-1s is further influenced by oncogenic signals and induces metabolic programs favoring cell growth and proliferation as well as tumor progression. Recently, cholesterol has been identified as a natural ERRα ligand using a combined biochemical strategy. This new finding highlighted some important physiological aspects related to the use of cholesterol-lowering drugs such as statins and bisphosphonates. Even more meaningful is the link between increased cholesterol levels and certain cancer phenotypes characterized by an overexpressed ERRα such as mammary, prostatic, and colorectal cancers, where the metabolic adaptation affects many cancer processes. Moreover, high-energy demanding cancer-related processes are strictly related to the cross-talk between tumor cells and some key players of tumor microenvironment, such as tumor-associated macrophage that fuels cancer progression. Some evidence suggests that high cholesterol content and ERRα activity favor the inflammatory environment by the production of different cytokines. In this review, starting from the most recent observations on the physiological role of the new signaling activated by the natural ligand of ERRα, we propose a new hypothesis on the suitability to control cholesterol levels as a chance in modulating ERRα activity in those tumors in which its expression and activity are increased.
How bacterial pathogens exploit host metabolism to promote immune tolerance and persist in infected hosts remains elusive. To achieve this, we show that Pseudomonas aeruginosa (PA), a recalcitrant pathogen, utilizes the quorum sensing (QS) signal 2-aminoacetophenone (2-AA). Here, we unveil how 2-AA-driven immune tolerization causes distinct metabolic perturbations in macrophages mitochondrial respiration and bioenergetics. We found that the 2-AA tolerization impairs oxidative phosphorylation (OXPHOS), leading to decreased generation of the crucial energy metabolite ATP and histone acetylation acetyl-CoA. We provide evidence that these effects result from reduced pyruvate flux into mitochondria due to the decreased expression of the mitochondrial pyruvate carrier (MPC1) mediated via the reduced expression and nuclear presence of its transcriptional regulator estrogen-related nuclear receptor (ERRα), leading to the weaker binding of ERRα to MPC1 promoter. This is the outcome of the hampered interaction of ERRα with the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) that ultimately leads to reduced pyruvate flux into mitochondria and ATP production in tolerized macrophages. Exogenously added ATP in 2-AA exposed macrophages restores the transcript levels of MPC1 and ERR-α and enhances cytokine production and intracellular bacterial clearance. Consistent with the in vitro findings, murine infection studies corroborate the 2-AA-mediated long-lasting decrease in ATP and acetyl-CoA and its association with PA persistence, further supporting this QS signaling molecule as the culprit of the host bioenergetic impairment and PA persistence. These findings unveil 2-AA as a negative modulator of cellular immunometabolism implicating the PGC-1α/ERRα axis in its influence on MPC1/OXPHOS-dependent energy production and PA clearance. These findings shed light on the underlying mechanisms of host tolerance and on potential therapeutic strategies to combat persistent PA infections.
Cell migration is essential throughout the life of multicellular organisms, and largely depends on the spatial and temporal regulation of cytoskeletal dynamics, cell adhesion and signal transduction. Interestingly, Estrogen-related receptor alpha (ERRα) has been identified as a major regulator of cell migration in both physiological and pathological conditions. ERRα is an orphan member of the nuclear hormone receptor superfamily of transcription factors and displays many biological functions. ERRα is a global regulator of energy metabolism, and it is also highly involved in bone homeostasis, development, differentiation, immunity and cancer progression. Importantly, in some instances, the regulation of these biological processes relies on the ability to orchestrate cell movements. Therefore, this review describes how ERRα-mediated cell migration contributes not only to tissue homeostasis but also to tumorigenesis and metastasis, and highlights the molecular and cellular mechanisms by which ERRα finely controls the cell migratory potential.
Tamoxifen, a triphenylethylene-based selective estrogen-receptor modulator, is a landmark drug for the treatment of breast cancer and is also used for treating liver cancer and osteoporosis. Structural studies of tamoxifen have led to the synthesis of more than 20 novel tamoxifen analogs as receptor modulators, including 16 ERα modulators 2–17, an ERRβ inverse agonist 19 and six ERRγ inverse agonists 20–25. This paper summarizes the research progress and structure–activity relationships of tamoxifen analogs modulating these three nuclear receptors reported in the literature, and introduces the relationship between these three nuclear receptor-mediated diseases and tamoxifen analogs to guide the research of novel tamoxifen analogs.
Angelica sinensis polysaccharide (ASP) showed increasingly recognized hepatoprotective effects and lipid regulation. Because polysaccharides are typically degraded into fragments or short-chain fatty acids in the gut, rather than being absorbed in their intact form, it is worth pondering why ASP can regulate hepatic lipid metabolism and protect the liver from damage caused by lipid accumulation. In vivo and in vitro nonalcoholic fatty liver disease (NAFLD) models with lipid accumulation were established to investigate the effect and potential mechanisms of ASP on hepatic fat accumulation. Our results showed that ASP remodeled the composition and abundance of the gut microbiota in high-fat diet-fed mice and increased their levels of propionate (0.92 ± 0.30 × 107 vs. 2.13 ± 0.52 × 107 ) and butyrate (1.83 ± 1.31 × 107 vs. 6.39 ± 1.44 × 107 ). Sodium propionate significantly increased the expression of estrogen-related receptor α (ERRα) in liver cells (400 mM sodium propionate for 2.19-fold increase) and alleviated the progress of NAFLD in methionine-choline-deficient diet model. Taken together, our study demonstrated that ASP can regulate hepatic lipid metabolism via propionate/ERRα pathway and ultimately relieving NAFLD. Our findings demonstrate that ASP can be used as a health care product or food supplement to prevent NAFLD.
Ginseng, when used as a food and nutritional supplement, has the ability to regulate human immunity. Here, the potential anti-hepatic fibrosis effect of ginsenoside Rd (Rd), one of the protopanaxadiol types of ginsenoside, was investigated. We established a hepatic fibrosis model using intraperitoneal injection of thioacetamide (TAA) for five weeks in mice. In addition, an in vitro model was established by using TGF-β to activate hepatic stellate cells (HSCs), treated with Rd and an estrogen-related receptor α (ERRα) inhibitor (XCT-790). The ERRα knockdown (shRNA-ERRα) of the primary mouse hepatocytes was used to establish hepatocyte injury by TGF-β, and they were then incubated in Rd. The Rd significantly alleviated the histopathological changes, and reduced the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. The Rd could upregulate the ERRα and downregulate the fibrosis markers in the livers of mice. In TAA-induced mice, the Rd inhibited the purinergic ligand-gated ion channel 7 receptor (P2X7r)-mediated NLRP3 inflammasome activation, consequently reversing the liver inflammatory response. The Rd significantly increased the expression of ERRα and suppressed the extracellular matrix (ECM) in the HSCs or primary hepatocytes. The Rd significantly decreased the P2X7r-mediated NLRP3 inflammasome activation, consequently reversing the inflammatory response, including the production of IL-1β, IL-23 in the activated HSCs and primary hepatocytes. The Rd could ameliorate the damage of the hepatocytes and further inhibit the entry of IL-1β and IL-18 into the extracellular matrix. The Rd reduced the inflammatory reaction by regulating the ERRα-P2X7r signaling pathway while suppressing the fibrogenesis, which suggests that the Rd can serve as a novel dietary supplement approach to combat hepatic fibrosis.
Skeletal muscle is a highly plastic tissue which can alter its metabolic and contractile features, as well as regenerative potential in response to exercise and other conditions. Multiple signaling factors including metabolites, kinases, receptors and transcriptional factors have been studied in the regulation of skeletal muscle plasticity. Recently, estrogen-related receptors (ERRs) have emerged as a critical transcriptional hub in control of skeletal muscle homeostasis. ERRα and ERRγ - the two highly expressed ERR sub-types in the muscle respond to various extracellular cues such as exercise, hypoxia, fasting and dietary factors, in turn regulating gene expression in the skeletal muscle. On the other hand, conditions such as diabetes and muscular dystrophy suppress expression of ERRs in the skeletal muscle, likely contributing to disease progression. We highlight key functions of ERRs in the skeletal muscle including the regulation of fiber type, mitochondrial metabolism, vascularization and regeneration. We also describe how ERRs are regulated in the skeletal muscle, and their interaction with important muscle regulators (e.g. AMPK and PGCs). Finally, we identify critical gaps in our understanding of ERR signaling in the skeletal muscle, and suggest future areas of investigation to advance ERRs as potential targets for function promoting therapeutics in muscle diseases.
Members of estrogen-related receptors (ERRs) are orphan nuclear receptors (NRs) that play primary roles in mitochondrial biogenesis and bioenergetics. The ERRs regulate a range of cellular functions, including oxidative phosphorylation (OXPHOS) as well as glucose and lipid metabolism. ERRs are considered important targets for the treatment of metabolic diseases, particularly type II diabetes (T2D), insulin resistance (IR) and obesity. In this review, we will overview the transcriptional network regulated by the members of ERR transcriptional factors and elaborate on the regulation of ERR via its binding to PGC-1α, the primary co-activator of ERR as well as post-translational regulation of ERRs by upstream kinase signals. Recent development in ERR’s cellular function has identified lipid metabolism/lipogenesis as a process that ERR regulates, and this function significantly impacts metabolic syndrome. Here, we will focus on their roles in lipid metabolic regulation and discuss the in vivo functions of ERRs in the development of non-alcoholic fatty liver disease (NAFLD), a comorbid metabolic syndrome concurrent with T2D, IR as well as obesity. Finally, we will explore ERRs as potential therapeutic targets by discussing the ligands that serve as antagonist/agonists for ERRs as well as efforts that target DNA binding of ERR as a transcriptional factor.
Mitochondria are highly-dynamic, membrane-bound organelles that generate most of the chemical energy needed to power the biochemical reactions in eukaryotic cells. These organelles also communicate with the nucleus and other cellular structures to help maintain somatic homeostasis, allow cellular adaptation to stress, and help maintain the developmental trajectory. Mitochondria also perform numerous other functions to support metabolic, energetic, and epigenetic regulation in our cells. There is increasing information on various disorders caused by defects in intrinsic mitochondrial or supporting nuclear genes in different organ systems. In this review, we have summarized the ultrastructural morphology, structural components, our current understanding of the evolution, biogenesis, dynamics, function, clinical manifestations of mitochondrial dysfunction, and future possibilities. The implications of deficits in mitochondrial dynamics and signaling for embryo viability and offspring health are also explored. We present information from our own clinical and laboratory research in conjunction with information collected from an extensive search in the databases PubMed, EMBASE, and Scopus.
The discovery of small molecules that regulate specific neuronal phenotypes is important for the development of new therapeutic candidates for neurological diseases. Estrogen-related receptor γ (ERRγ), an orphan nuclear receptor widely expressed in the central nervous system (CNS), is closely related to the regulation of neuronal metabolism and differentiation. We previously reported that upregulation of ERRγ could enhance dopaminergic neuronal phenotypes in the neuroblastoma cell line, SH-SY5Y. In this study, we designed and synthesized a series of new ERRγ agonists using the X-ray crystal structure of the GSK4716-bound ERRγ complex and known synthetic ligands. Our new ERRγ agonists exhibited increased transcriptional activities of ERRγ. In addition, our molecular docking results supported the experimental findings for ERRγ agonistic activity of the potent analogue, 5d. Importantly, 5d not only enhanced the expression of dopaminergic neuronal-specific molecules, TH and DAT but also activated the relevant signaling events, such as the CREB-mediated signaling pathway. The results of the present study may provide useful clues for the development of novel ERRγ agonists for neurological diseases related to the dopaminergic nervous system.
Estrogen related receptors are orphan members of the nuclear receptor superfamily acting as transcription factors (TFs). In contrast to classical nuclear receptors, the activities of the ERRs are not controlled by a natural ligand. Regulation of their activities thus relies on availability of transcriptional co-regulators. In this paper, we focus on ERRα, whose involvement in cancer progression has been broadly demonstrated. We propose a new approach to identify potential co-activators, starting from previously identified ERRα-activated genes in a breast cancer (BC) cell line. Considering mRNA gene expression from two sets of human BC cells as major endpoint, we used sparse partial least squares modeling to uncover new transcriptional regulators associated with ERRα. Among them, DDX21, MYBBP1A, NFKB1, and SETD7 are functionally relevant in MDA-MB-231 cells, specifically activating the expression of subsets of ERRα-activated genes. We studied SET7 in more details and showed its co-localization with ERRα and its ERRα-dependent transcriptional and phenotypic effects. Our results thus demonstrate the ability of a modeling approach to identify new transcriptional partners from gene expression. Finally, experimental results show that ERRα cooperates with distinct co-regulators to control the expression of distinct sets of target genes, thus reinforcing the combinatorial specificity of transcription.
Drugs that kill tumors through multiple mechanisms have potential for broad clinical benefits, with a reduced propensity to resistance. We developed BipotentR, a computational approach to find cancer-cell-specific regulators that simultaneously modulate tumor immunity and another oncogenic pathway. Using tumor metabolism as proof-of-principle, BipotentR identified 38 candidate immune-metabolic regulators by combining epigenomes with bulk and single-cell tumor transcriptomes from patients. Inhibition of top candidate ESRRA (Estrogen Related Receptor Alpha) killed tumors by direct effects on energy metabolism and two immune mechanisms: (i) cytokine induction, causing proinflammatory macrophage polarization (ii) antigen-presentation stimulation, recruiting CD8 ⁺ T cells into tumors. ESRRA is activated in immune-suppressive and immunotherapy-resistant tumors of many types, suggesting broad clinical relevance. We also applied BipotentR to angiogenesis and growth-suppressor pathways, demonstrating a widely applicable approach to identify drug targets that act simultaneously through multiple mechanisms. BipotentR is publicly available at http://bipotentr.dfci.harvard.edu/ .
One-Sentence Summary
BipotentR identifies targets for bipotent anticancer drugs, as shown by the energy and immune effects of ESRRA inhibition.
Aim:
Copy number variations (CNVs) are related to the genetic and phenotypic diversity of cancers and identifying genetic alterations could improve treatment strategies. Here, we used The Cancer Genome Atlas (TCGA) to explore associations between estrogen-related receptor alpha (ESRRA) CNVs and histological grade in patients with ovarian cancer (OC).
Methods:
Gene expression data and clinical information of 620 OC patients were obtained from The Cancer Genome Atlas）TCGA and associations between ESRRA CNVs and clinical characteristics were evaluated. Multivariate logistic regression analyses to obtain odds ratios (ORs) using a 95% confidence interval (CI) were performed, adjusting for race, age, histological grade, and tumor size.
Results:
ESRRA CNVs were associated with histological grade (OR 0.6235 [95% CI, 0.3593-0.8877]; p < 0.05) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) CNVs (OR -0.6298 [95% CI, -0.9011 to -0.3585]; p < 0.05). In multivariate analyses, ESRRA CNVs remained significantly associated with histological grade (OR 0.6492 [95% CI, 0.3549-0.9435]; p < 0.05) and PPARGC1A CNVs (OR -0.6236 [95% CI, -0.9269 to 0.3203]; p < 0.05).
Conclusion:
There was a significant association between ESRRA CNVs in patients with OC and histological grade of the cancer.
Ruan jian qing mai formula (RJQM), a multi‐component herbal formula, has been widely used to treat peripheral arterial disease (PAD) in China. However, its active compounds and mechanisms of action are still unknown. Firstly, RNA sequencing analysis of 15 healthy and 16 PAD samples showed that 524 PAD differential genes (DEGs) were significantly enriched in Go Ontology (ribonucleotide metabolic process, oxidoreductase complex and electron transfer activity), KEGG and GSEA pathways (OXPHOS and TCA cycle), miRNA (MIR183) and kinase (PAK6). 53 active ingredients in RJQM had similar structures to the 7 drug molecules in CLUE. Then, network topology analysis of the 53 components‐target‐pathway‐disease network yielded 10 active ingredients. Finally, computational toxicity estimations showed that the median lethal dose (LD50) of the 10 active ingredients was above 1000mg/kg, and 8 of them did not cause hepatotoxicity, mutagenicity, carcinogenicity, cytotoxicity and immunotoxicity, nor activate 12 toxic pathways. In conclusion, RJQM has a protection effect on PAD by regulating a complex molecular network. Part of the mechanism is associated with the regulation of OXPHOS by 10 active components, which may alleviate mitochondrial dysfunction and pathological metabolic programming. This article is protected by copyright. All rights reserved
ERRα is a nuclear receptor whose activity mainly depends on its interaction with transcription co-regulators. High levels of ERRα are found in various cancer types and correlate with poor prognosis. However, the mechanisms linking ERRα to cancer cell migration as well as the coregulators involved are unclear. In our study, we found two histone-modifying enzymes, LSD1 and SET7, acting as positive regulators of ERRα.I. ERRα impacts the biochemical activities of the LSD1 demethylase. Activation of ERRα -LSD1 targets (identified by RNA-Seq) requires the recruitment of this complex at Transcriptional Start Sites (TSSs), which is achieved by the NRF1 transcription factor. In our study, we have shown several points: NRF1, but not ERRα , is involved in positioning LSD1 to TSS, whereas ERRα , but not NRF1, regulates LSD1 enzymatic activities towards demethylating H3K9me2.II. A distinct group of ERRa target genes (identified by RNA-Seq) is under the control of the histone methyltransferase SET7 which mono-methylates H3K4. Appropriate recruitment of SET7 at TSSs is controlled by the ETS1 transcription factor, promoting the interaction between SET7-ERRa, leading to target gene expression.Gene Ontology analysis revealed that ERRa-LSD1 co-targets, as well as ERRa-SET7 co-targets, are enriched in terms of cell invasion. Consistently, depletion of each of these factors, as well as depletion of NRF1 or ETS1, leads to reduced cell invasion capacities as observed in transwell assays or in vivo, using xenotransplantation in the zebrafish embryo.Altogether, our results show two regulatory networks involving histone modifications induced by nuclear receptors, leading to increased cell invasion.
Mutation of rod photoreceptor-enriched transcription factors is a major cause of inherited blindness. We identified the orphan nuclear hormone receptor estrogen-related receptor β (ERRβ) as selectively expressed in rod photoreceptors. Overexpression of ERRβ induces expression of rod-specific genes in retinas of wild-type as well as Nrl−/− mice, which lack rod photoreceptors. Mutation of ERRβ results in dysfunction and degeneration of rods, whereas inverse agonists of ERRβ trigger rapid rod degeneration, which is rescued by constitutively active mutants of ERRβ. ERRβ coordinates expression of multiple genes that are rate-limiting regulators of ATP generation and consumption in photoreceptors. Furthermore, enhancing ERRβ activity rescues photoreceptor defects that result from loss of the photoreceptor-specific transcription factor Crx. Our findings demonstrate that ERRβ is a critical regulator of rod photoreceptor function and survival, and suggest that ERRβ agonists may be useful in the treatment of certain retinal dystrophies.
The human estrogen-related receptor alpha 1 (hERR alpha 1) is an orphan member of the steroid/thyroid hormone receptor superfamily. A cDNA encoding this protein was originally isolated on the basis of sequence similarity in its DNA-binding domain with estrogen receptor alpha (ER alpha). Previously, we reported the purification of hERR alpha 1 from HeLa cell nuclear extracts on the basis of its ability to bind two sites in the late promoter of simian virus 40 (SV40). We have now determined the primary structure and the DNA and protein binding specificities of hERR alpha 1 and developed in vivo and in vitro assays for its functional activities. hERR alpha 1 was found to bind as a monomer, with a high-affinity binding site containing the extended half-site sequence 5'-TCAAG-GTCA-3'. Binding sites for hERR alpha 1 were identified in many cellular promoters, including some that were previously shown to function as estrogen-response elements (EREs). hERR alpha 1 was shown to function as a sequence-specific repressor of the SV40 late promoter in both cell culture and cell-free transcription systems. It was also shown to interact with both ER alpha and the transcription factor TFIIB by direct protein-protein contacts. Thus, hERR alpha 1 may play a role in the response of some genes to estrogen via heterodimerization with ERs or competition with ERs for binding to EREs.
Overexpression of ERBB2 and its neighboring genes on chromosome 17 occurs in approximately 25% of breast tumors and is associated with poor prognosis. While amplification of the 17q12-21 chromosomal region often correlates with an increase in the transcriptional rates of the locus, the molecular mechanisms and the factors involved in the coordinated expression of genes residing within the ERBB2 amplicon remain largely unknown. Here we demonstrate that estrogen-related receptor α (ERRα, NR3B1) and its coregulator PGC-1β are key effectors in this process. Using a mouse model of ERBB2-initiated mammary tumorigenesis, we first show that ablation of ERRα significantly delays ERBB2-induced tumor development and lowers the levels of amplicon transcripts. Chromosome 17q-wide binding site location analyses in human breast cancer cells show preferential recruitment of ERRα to DNA segments associated with the ERBB2 amplicon. Furthermore, ERRα directs the co-recruitment of the coactivator PGC-1β to segments in the 17q12 region and the recruitment of RNA polymerase II to the promoters of the ERBB2 and coamplified genes. ERRα and PGC-1β also participate in the de-repression of ERBB2 expression through competitive genomic cross-talk with estrogen receptor α (ERα) and, as a consequence, influence tamoxifen sensitivity in breast cancer cells. Taken together, our results suggest that ERRα and PGC-1β are key players in the etiology of malignant breast cancer by coordinating the transcriptional regulation of genes located in the 17q12 region, a process that also involves interference with the repressive function of ERα on ERBB2 expression.
Cancer cell metabolism is often characterized by a shift from an oxidative to a glycolytic bioenergetics pathway, a phenomenon known as the Warburg effect. miR-378(∗) is embedded within PPARGC1b which encodes PGC-1β, a transcriptional regulator of oxidative energy metabolism. Here we show that miR-378(∗) expression is regulated by ERBB2 and induces a metabolic shift in breast cancer cells. miR-378(∗) performs this function by inhibiting the expression of two PGC-1β partners, ERRγ and GABPA, leading to a reduction in tricarboxylic acid cycle gene expression and oxygen consumption as well as an increase in lactate production and in cell proliferation. In situ hybridization experiments show that miR-378(∗) expression correlates with progression of human breast cancer. These results identify miR-378(∗) as a molecular switch involved in the orchestration of the Warburg effect in breast cancer cells via interference with a well-integrated bioenergetics transcriptional pathway.
Gene regulatory networks are based on simple building blocks such as promoters, transcription factors (TFs) and their binding sites on DNA. But how diverse are the functions that can be obtained by different arrangements of promoters and TF binding sites? In this work we constructed synthetic regulatory regions using promoter elements and binding sites of two noninteracting TFs, each sensing a single environmental input signal. We show that simply by combining these three kinds of elements, we can obtain 11 of the 16 Boolean logic gates that integrate two environmental signals in vivo. Further, we demonstrate how combination of logic gates can result in new logic functions. Our results suggest that simple elements of transcription regulation form a highly flexible toolbox that can generate diverse functions under natural selection.
Mutation of rod photoreceptor-enriched transcription factors is a major cause of inherited blindness. We identified the orphan nuclear hormone receptor estrogen-related receptor beta (ERRbeta) as selectively expressed in rod photoreceptors. Overexpression of ERRbeta induces expression of rod-specific genes in retinas of wild-type as well as Nrl(-/-) mice, which lack rod photoreceptors. Mutation of ERRbeta results in dysfunction and degeneration of rods, whereas inverse agonists of ERRbeta trigger rapid rod degeneration, which is rescued by constitutively active mutants of ERRbeta. ERRbeta coordinates expression of multiple genes that are rate-limiting regulators of ATP generation and consumption in photoreceptors. Furthermore, enhancing ERRbeta activity rescues photoreceptor defects that result from loss of the photoreceptor-specific transcription factor Crx. Our findings demonstrate that ERRbeta is a critical regulator of rod photoreceptor function and survival, and suggest that ERRbeta agonists may be useful in the treatment of certain retinal dystrophies.
Estrogen-related receptor alpha (ERRalpha) and proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) play central roles in the transcriptional control of energy homeostasis, but little is known about factors regulating their activity. Here we identified the homeobox protein prospero-related homeobox 1 (Prox1) as one such factor. Prox1 interacts with ERRalpha and PGC-1alpha, occupies promoters of metabolic genes on a genome-wide scale, and inhibits the activity of the ERRalpha/PGC-1alpha complex. DNA motif analysis suggests that Prox1 interacts with the genome through tethering to ERRalpha and other factors. Importantly, ablation of Prox1 and ERRalpha have opposite effects on the respiratory capacity of liver cells, revealing an unexpected role for Prox1 in the control of energy homeostasis.
Energy production by oxidative metabolism in kidney, stomach, and heart, is primarily expended in establishing ion gradients to drive renal electrolyte homeostasis, gastric acid secretion, and cardiac muscle contraction, respectively. In addition to orchestrating transcriptional control of oxidative metabolism, the orphan nuclear receptor, estrogen-related receptor gamma (ERRgamma), coordinates expression of genes central to ion homeostasis in oxidative tissues. Renal, gastric, and cardiac tissues subjected to genomic analysis of expression in perinatal ERRgamma null mice revealed a characteristic dysregulation of genes involved in transport processes, exemplified by the voltage-gated potassium channel, Kcne2. Consistently, ERRgamma null animals die during the first 72 h of life with elevated serum potassium, reductions in key gastric acid production markers, and cardiac arrhythmia with prolonged QT intervals. In addition, we find altered expression of several genes associated with hypertension in ERRgamma null mice. These findings suggest a potential role for genetic polymorphisms at the ERRgamma locus and ERRgamma modulators in the etiology and treatment of renal, gastric, and cardiac dysfunction.
Estrogen-related receptor alpha (ERRalpha) is an orphan nuclear receptor highly expressed in the kidney, an organ playing a central role in blood pressure regulation through electrolyte homeostasis and the renin-angiotensin system. Physiological analysis revealed that, relative to wild-type mice, ERRalpha null mice are hypotensive despite significant hypernatremia, hypokalemia, and slight hyperreninemia. Using a combination of genome-wide location analysis and expression profiling, we demonstrate that ERRalpha regulates the expression of channels involved in renal Na(+) and K(+) handling (Scnn1a, Atp1a1, Atp1b1) and altered in Bartter syndrome (Bsnd, Kcnq1). In addition, ERRalpha regulates the expression of receptors implicated in the systemic regulation of blood pressure (Ghr, Gcgr, Lepr, Npy1r) and of genes within the renin-angiotensin pathway (Ren1, Agt, Ace2). Our study thus identifies ERRalpha as a pleiotropic regulator of renal control of blood pressure, renal Na(+)/K(+) homeostasis, and renin-angiotensin pathway and suggests that modulation of ERRalpha activity could represent a potential avenue for the management of hypertension.
Genomes are organized into high-level three-dimensional structures, and DNA elements separated by long genomic distances can in principle interact functionally. Many transcription factors bind to regulatory DNA elements distant from gene promoters. Although distal binding sites have been shown to regulate transcription by long-range chromatin interactions at a few loci, chromatin interactions and their impact on transcription regulation have not been investigated in a genome-wide manner. Here we describe the development of a new strategy, chromatin interaction analysis by paired-end tag sequencing (ChIA-PET) for the de novo detection of global chromatin interactions, with which we have comprehensively mapped the chromatin interaction network bound by oestrogen receptor alpha (ER-alpha) in the human genome. We found that most high-confidence remote ER-alpha-binding sites are anchored at gene promoters through long-range chromatin interactions, suggesting that ER-alpha functions by extensive chromatin looping to bring genes together for coordinated transcriptional regulation. We propose that chromatin interactions constitute a primary mechanism for regulating transcription in mammalian genomes.
Estrogen-related receptor alpha (ERRalpha) is an orphan nuclear receptor, the expression of which correlates with negative prognosis in breast cancer. ERRalpha shares functional features with the estrogen receptor alpha (ERalpha) and its activity is modulated by the ERBB2 signaling pathway. Using genome-wide binding sites location analyses in ERalpha-positive and ERalpha-negative breast cancer cell lines, we show that ERRalpha and ERalpha display strict binding site specificity and maintain independent mechanisms of transcriptional activation. Nonetheless, ERRalpha and ERalpha coregulate a small subset of common target genes via binding either to a dual-specificity binding site or to distinct cognate binding sites located within the extended promoter region of the gene. Although ERRalpha signaling in breast cancer cells is mostly independent of ERalpha, the small fraction of common ERRalpha/ERalpha targets comprises genes with high relevance to breast tumor biology, including genes located within the ERBB2 amplicon and GATA3. Finally, unsupervised hierarchical clustering based on the expression profiling of ERRalpha direct target genes in human breast tumors revealed four main clusters that recapitulate established tumor subtypes. Taken together, the identification and functional characterization of the ERRalpha transcriptional network implicate ERRalpha signaling as a determinant of breast cancer heterogeneity.
The flurry of recent publications regarding reprogramming of mature cell types to induced pluripotent stem cells raises the question: what exactly is pluripotency? A functional definition is provided by examination of the developmental potential of pluripotent stem cell types. Defining pluripotency at the molecular level, however, can be a greater challenge. Here, we examine the emerging list of genes associated with induced pluripotency, with particular attention to their functional requirement in the mouse embryo. Knowledge of the requirement for these genes in the embryo and in embryonic stem cells will advance our understanding of how to reverse the developmental clock for therapeutic benefit.
The orphan nuclear receptor ERRβ is expressed in undifferentiated trophoblast stem cell lines and extraembryonic ectoderm, and genetic ablation of ERRβ results in abnormal trophoblast proliferation and precocious differentiation toward the giant cell lineage. Here, we show that the synthetic estrogen diethylstilbestrol (DES) promotes coactivator release from ERRβ and inhibits its transcriptional activity. Strikingly, treatment of trophoblast stem cells with DES led to their differentiation toward the polyploid giant cell lineage. In addition, DES-treated pregnant mice exhibited abnormal early placenta development associated with an overabundance of trophoblast giant cells and an absence of diploid trophoblast. These results define a novel pathway for DES action and provide evidence for steroidlike control of trophoblast development.
Background:
The orphan nuclear receptor estrogen-related receptor alpha (ERRalpha) is a member of the nuclear receptor superfamily. It was identified through a search for genes encoding proteins related to estrogen receptor alpha (ERalpha). An endogenous ligand has not been found. Novel ERRalpha antagonists that are highly specific for binding to the ligand binding domain (LBD) of ERRalpha have been recently reported. Research suggests that ERRalpha may be a novel drug target to treat breast cancer and/or metabolic disorders and this has led to an effort to characterize the mechanisms of action of N-[(2Z)-3-(4,5-dihydro-1,3-thiazol-2-yl)-1,3-thiazolidin-2-yl idene]-5H dibenzo[a,d][7]annulen-5-amine, a novel ERRalpha specific antagonist.
Methodology/principal findings:
We demonstrate this ERRalpha ligand inhibits ERRalpha transcriptional activity in MCF-7 cells by luciferase assay but does not affect mRNA levels measured by real-time RT-PCR. Also, ERalpha (ESR1) mRNA levels were not affected upon treatment with the ERRalpha antagonist, but other ERRalpha (ESRRA) target genes such as pS2 (TFF1), osteopontin (SPP1), and aromatase (CYP19A1) mRNA levels decreased. In vitro, the ERRalpha antagonist prevents the constitutive interaction between ERRalpha and nuclear receptor coactivators. Furthermore, we use Western blots to demonstrate ERRalpha protein degradation via the ubiquitin proteasome pathway is increased by the ERRalpha-subtype specific antagonist. We demonstrate by chromatin immunoprecipitation (ChIP) that the interaction between ACADM, ESRRA, and TFF1 endogenous gene promoters and ERRalpha protein is decreased when cells are treated with the ligand. Knocking-down ERRalpha (shRNA) led to similar genomic effects seen when MCF-7 cells were treated with our ERRalpha antagonist.
Conclusions/significance:
We report the mechanism of action of a novel ERRalpha specific antagonist that inhibits transcriptional activity of ERRalpha, disrupts the constitutive interaction between ERRalpha and nuclear coactivators, and induces proteasome-dependent ERRalpha protein degradation. Additionally, we confirmed that knocking-down ERRalpha lead to similar genomic effects demonstrated in vitro when treated with the ERRalpha specific antagonist.
Nuclear receptors (NRs) regulate gene expression in essential biological processes including differentiation and development. Here we report the systematic profiling of NRs in human and mouse embryonic stem cell (ESC) lines and during their early differentiation into embryoid bodies. Expression of the 48 human and mouse NRs was assessed by quantitative real-time PCR. In general, expression of NRs between the two human cell lines was highly concordant, whereas in contrast, expression of NRs between human and mouse ESCs differed significantly. In particular, a number of NRs that have been implicated previously as crucial regulators of mouse ESC biology, including ERRbeta, DAX-1, and LRH-1, exhibited diametric patterns of expression, suggesting they may have distinct species-specific functions. Taken together, these results highlight the complexity of the transcriptional hierarchy that exists between species and governs early development. These data should provide a unique resource for further exploration of the species-specific roles of NRs in ESC self-renewal and differentiation.
The dominant effect of transcription factors in imparting expanded potency is best exemplified by the reprogramming of fibroblasts to pluripotent cells using retrovirus-mediated transduction of defined transcription factors. In the murine system, Oct4, Sox2, c-Myc and Klf4 are sufficient to convert fibroblasts to induced pluripotent stem (iPS) cells that have many characteristics of embryonic stem (ES) cells. Here we show that the orphan nuclear receptor Esrrb functions in conjunction with Oct4 and Sox2 to mediate reprogramming of mouse embryonic fibroblasts (MEFs) to iPS cells. Esrrb-reprogrammed cells share similar expression and epigenetic signatures as ES cells. These cells are also pluripotent and can differentiate in vitro and in vivo into the three major embryonic cell lineages. Furthermore, these cells contribute to mouse chimaeras and are germline transmissible. In ES cells, Esrrb targets many genes involved in self-renewal and pluripotency. This suggests that Esrrb may mediate reprogramming through the upregulation of ES-cell-specific genes. Our findings also indicate that it is possible to reprogram MEFs without exogenous Klf transcription factors and link a nuclear receptor to somatic cell reprogramming.
Expression of estrogen-related receptor alpha (ERRalpha) has recently been shown to carry negative prognostic significance in breast and ovarian cancers. The specific role of this orphan nuclear receptor in tumor growth and progression, however, is yet to be fully understood. The significant homology between estrogen receptor alpha (ERalpha) and ERRalpha initially suggested that these receptors may have similar transcriptional targets. Using the well-characterized ERalpha-positive MCF-7 breast cancer cell line, we sought to gain a genome-wide picture of ERalpha-ERRalpha cross-talk using an unbiased microarray approach. In addition to generating a host of novel ERRalpha target genes, this study yielded the surprising result that most ERRalpha-regulated genes are unrelated to estrogen signaling. The relatively small number of genes regulated by both ERalpha and ERRalpha led us to expand our study to the more aggressive and less clinically treatable ERalpha-negative class of breast cancers. In this setting, we found that ERRalpha expression is required for the basal level of expression of many known and novel ERRalpha target genes. Introduction of a small interfering RNA directed to ERRalpha into the highly aggressive breast carcinoma MDA-MB-231 cell line dramatically reduced the migratory potential of these cells. Although stable knockdown of ERRalpha expression in MDA-MB-231 cells had no effect on in vitro cell proliferation, a significant reduction of tumor growth rate was observed when these cells were implanted as xenografts. Our results confirm a role for ERRalpha in breast cancer growth and highlight it as a potential therapeutic target for estrogen receptor-negative breast cancer.
The gonads and adrenal glands produce steroids classified into five major groups which include the oestrogens, progestins, androgens, glucocorticoids and mineralocorticoids. Gonadal steroids control the differentiation and growth of the reproductive system, induce and maintain sexual characteristics and modulate reproductive behaviour. Adrenal steroids also influence differentiation as well as being metabolic regulators. The effects of each steroid depend primarily on its specific receptors, the nature of which could therefore provide a basis for classification of steroid hormone action. The successful cloning, sequencing and expression of the human glucocorticoid (hGR) (ref. 1), oestrogen (hER), progesterone (hPR), and mineralocorticoid (hMR) receptors, complementary DNA, plus homologues from various species, provides the first opportunity to study receptor structure and its influence on gene expression. Sequence comparison and mutational analysis show structural features common to all groups of steroid hormone receptors. The receptors share a highly conserved cysteine-rich region which functions as the DNA-binding domain. This common segment allows the genome to be scanned for related gene products: hMR cDNA for example, was isolated using an hGR hybridization probe. In this study, using the DNA-binding domain of the human oestrogen receptor cDNA as a hybridization probe, we have isolated two cDNA clones encoding polypeptides with structural features suggestive of cryptic steroid hormone receptors which could participate in a new hormone response system.
We have shown previously that estrogen-stimulated transcription from the human lactoferrin gene in RL95-2 endometrium carcinoma cells is mediated through an imperfect estrogen response element (ERE) at the 5 -flanking region of the gene. Upstream from the ERE, a DNA sequence (-418 to -378, FP1) was selectively protected from DNase I digestion by nuclear extracts from endometrial and mammary gland cell lines. In this report, using the electrophoresis mobility shift assay, site-directed mutagenesis, and DNA methylation interference analyses, we show that three different nuclear proteins bind to the FP1 region (C1, C2, and C3 sites). The nuclear receptor, COUP-TF, binds to the C2 site. Mutations in the C1 binding region abolish C1 complex formation and reduce estrogen-dependent transcription from the lactoferrin ERE. When the imperfect ERE of the lactoferrin gene is converted to a perfect palindromic structure, the enhancing effect of the C1 binding element for estrogen responsiveness was abolished. We isolated a complementary DNA (cDNA) clone from an RL95-2 expression library that encodes the C1 site-binding protein. The encoded polypeptide maintains 99% amino acid identity with the previously described orphan nuclear receptor hERR1. A 2.2-kilobase mRNA was detected in RL95-2 cells by the newly isolated cDNA but not by the first 180 base pair of the published hERR1 sequence. By Western analysis, a major 42-kDa protein is detected in the RL95-2 nuclear extract with antibody generated against GST-hERR1 fusion protein. Finally, we show that the hERR1 interacts with the human estrogen receptor through protein-protein contacts.
Estrogen-related receptor alpha (ERR alpha) is an orphan member of the superfamily of nuclear hormone receptors. ERR alpha was initially isolated based on its sequence homology to the estrogen receptor but is not activated by classic estrogens. To identify possible physiologic functions for this orphan receptor, we cloned the mouse ERR alpha cDNA and used it to characterize the expression of ERR alpha transcripts and to identify potential ERR alpha target genes. RNA in situ hybridization studies detect ERR alpha transcripts in an organ-specific manner through mid- to late embryonic development, with persistent high-level expression in brown adipose tissue and intestinal mucosa. In the adult mouse, ERR alpha is most highly expressed in kidney, heart, and brown adipocytes, tissues which preferentially metabolize fatty acids. Binding site selection experiments show that ERR alpha preferentially binds to an ERR alpha response element (ERRE) containing a single consensus half-site, TNAAGGTCA. An ERRE is present in the 5'-flanking region of the gene encoding medium-chain acyl coenzyme A dehydrogenase (MCAD), a key enzyme involved in the mitochondrial beta-oxidation of fat. The MCAD nuclear receptor response element 1 (NRRE-1) interacts in vitro with ERR alpha expressed in COS-7 cells. Supershift experiments show that endogenous ERR alpha present in nuclear extracts obtained from a brown fat tumor cell line (HIB) interacts with NRRE-1. In the absence of its putative ligand, ERR alpha does not activate the MCAD promoter in transient transfection studies; however, a VP16-ERR alpha chimera activates natural and synthetic promoters containing NRRE-1. In addition, ERR alpha efficiently represses retinoic acid induction mediated by NRRE-1. These results demonstrate that ERR alpha can control the expression of MCAD through the NRRE-1 and thus may play an important role in regulating cellular energy balance in vivo.
Little is known about the factors involved in the brown adipocyte gene regulatory program. In contrast to the white adipocyte, the brown adipocyte is characterized by abundant mitochondria and high level expression of mitochondrial fatty acid beta-oxidation enzymes. Previous studies in transgenic mice have shown that the brown adipose-enriched expression of a key beta-oxidation enzyme, medium chain acyl-coenzyme A dehydrogenase (MCAD), requires cis-acting elements located within the proximal promoter region of the MCAD gene. The levels of mRNA encoding MCAD and several other beta-oxidation cycle enzymes were coordinately induced during differentiation of brown adipocytes in culture. Expression of transgenes comprised of MCAD gene promoter fragments fused to chloramphenicol acetyltransferase reporters in differentiating brown adipocytes revealed that a known nuclear receptor response element (NRRE-1) was required for the transcriptional induction of the MCAD gene during brown adipocyte differentiation. Electrophoretic mobility shift assays and antibody recognition studies identified distinct brown adipocyte differentiation stage-specific, NRRE-1-protein complexes; the orphan nuclear receptors, chicken ovalbumin upstream promoter transcription factors I and II, were identified as major the NRRE-1 binding proteins in the pre-adipocyte, whereas the estrogen-related receptor alpha (ERRalpha) bound NRRE-1 in extracts prepared from differentiated brown adipocytes. DNA binding studies performed with a series of NRRE-1 mutant probes indicated that ERRalpha was capable of binding two distinct sites within NRRE-1, each of which conform to the known ERRalpha monomeric binding consensus. The expression of ERRalpha paralleled NRRE-1 binding activities and MCAD expression during brown adipocyte differentiation, cardiac development, and among a variety of adult mouse tissues. These results identify a new class of ERRalpha target genes and implicate ERRalpha and chicken ovalbumin upstream promoter transcription factor in the control of a pivotal metabolic pathway during brown adipocyte differentiation.
The physiological activities of estrogens are thought to be mediated by specific nuclear receptors, ERalpha and ERbeta. However, certain tissues, such as the bone, that are highly responsive to estrogens only express a low level of these receptors. Starting from this apparent contradiction, we have evaluated the potentials of two related receptors ERRalpha and ERRbeta to intervene in estrogen signaling. ERalpha, ERRalpha and ERRbeta bind to and activate transcription through both the classical estrogen response element (ERE) and the SF-1 response element (SFRE). In contrast, ERbeta DNA-binding and transcriptional activity is restricted to the ERE. Accordingly, the osteopontin gene promoter is stimulated through SFRE sequences, by ERRalpha as well as by ERalpha, but not by ERbeta. Analysis of the cross-talk within the ER/ERR subgroup of nuclear receptors thus revealed common targets but also functional differences between the two ERs.
Orphan nuclear receptors share sequence homology with members of the nuclear receptor superfamily, but ligands are unknown or unnecessary. A novel orphan receptor, estrogen receptor-related protein 3 (ERR3), was identified by yeast two-hybrid screening, using the transcriptional coactivator glucocorticoid receptor interacting protein 1 (GRIP1) as bait. The putative full-length mouse ERR3 contains 458 amino acids and is closely related to two known orphan receptors ERR1 and ERR2. All the ERR family members share an almost identical DNA-binding domain, which has 68% amino acid identity with that of estrogen receptor. ERR3 bound specifically to an estrogen response element and activated reporter genes controlled by estrogen response elements, both in yeast and in mammalian cells, in the absence of any added ligand. A conserved AF-2 activation domain located in the hormone-binding domain of ERR3 was primarily responsible for transcriptional activation. The ERR3 AF-2 domain bound GRIP1 in a ligand-independent manner both in vitro and in vivo, through the LXXLL motifs of GRIP1, and GRIP1 functioned as a transcriptional coactivator for ERR3 in both yeast and mammalian cells. Expression of ERR3 in adult mouse was restricted; highest expression was observed in heart, kidney, and brain. In the mouse embryo no expression was observed at day 7, and highest expression occurred around the 11-15 day stages. Although ERR3 is much more closely related to ERR2 than to ERR1, the expression pattern for ERR3 was similar to that of ERR1 and distinct from that for ERR2, suggesting a unique role for ERR3 in development.
In this report, we demonstrate that, in contrast to most previously characterized nuclear receptors, hERR1 and hERR2 (human estrogen receptor-related protein 1 and -2) are constitutive activators of the classic estrogen response element (ERE) as well as the palindromic thyroid hormone response element (TRE(pal)) but not the glucocorticoid response element (GRE). This intrinsically activated state of hERR1 and hERR2 resides in the ligand-binding domains of the two genes and is transferable to a heterologous receptor. In addition, we show that members of the p160 family of nuclear receptor coactivators, ACTR (activator of thyroid and retinoic acid receptors), GRIP1 (glucocorticoid receptor interacting protein 1), and SRC-1 (steroid receptor coactivator 1), potentiate the transcriptional activity by hERR1 and hERR2 in mammalian cells, and that both orphan receptors bind the coactivators in a ligand-independent manner. Together, these results suggest that hERR1 and hERR2 activate gene transcription through a mechanism different from most of the previously characterized steroid hormone receptors.
The human estrogen receptor-related receptor (ERRalpha1, NR3B1a) was shown to bind a steroidogenic factor binding element (SFRE), TCAAGGTCATC, 26 base pairs upstream from the estrogen response element (ERE) of the human lactoferrin gene promoter. A mutation made at SFRE significantly reduced estrogen-dependent transcription from the lactoferrin ERE in human endometrial cells. In this study, we demonstrated that ERRalpha1 binds both SFRE and ERE elements and constitutively transactivates the lactoferrin gene promoter. In DNase I footprinting protection analysis, both SFRE and ERE regions were protected by glutathione S-transferase-ERRalpha1 fusion protein. The receptor formed two protein-DNA complexes with either SFRE or ERE in electrophoresis mobility shift assay. Homodimerization of ERRalpha1 was confirmed with the mammalian two-hybrid system. ERRalpha1 activates reporter constructs containing various types of estrogen response elements in endometrial and non-endometrial cells in transient transfection experiments. Overexpressing the coactivator, SRC1a or GRIP1, further enhances ERRalpha1-induced transcriptional activity. We demonstrated that the AF2 domain of ERRalpha1 is essential for the transactivation function and that deletion or mutation at this region abrogates the activation capability. Protein-protein interaction between the SRC1a and ERRalpha1 C terminus was confirmed with a GST glutathione S-transferase "pull-down" assay. When comparing ERRalpha1 and the estrogen receptor alpha (ERalpha) in many of the experiments, we found that ERalpha can also bind SFRE of the lactoferrin gene and transactivate the promoter activity in a ligand-dependent manner. The present study demonstrated that ERRalpha1 binds similar DNA elements as ERalpha and confers its transactivation function constitutively. Therefore, ERRalpha1 may actively modulate the estrogen response of lactoferrin gene as well as other estrogen-responsive genes.
The estrogen-receptor-related receptors (ERRs) alpha, beta, and gamma are orphan nuclear hormone receptors that share significant homology with the estrogen receptors (ERs) but are not activated by natural estrogens. In contrast, the ERRs display constitutive transcriptional activity in the absence of exogenously added ligand. However, the ERRs bind to the estrogen response element and to the extended half-sites of which a subset can also be recognized by ERalpha, suggesting that ERRs and ERs may control overlapping regulatory pathways. To test this hypothesis, we explored the possibility that ERRs could regulate the expression of the estrogen-inducible pS2 gene, a human breast cancer prognostic marker. Transfection studies show that all of the ERR isoforms can activate the pS2 promoter in a variety of cell types, including breast cancer cell lines. Surprisingly, sequence analysis combined with mutational studies revealed that, in addition to the well-characterized estrogen response element, the presence of a functional extended half-site within the pS2 promoter is also required for complete response to both ER and ERR pathways. We show that ERR transcriptional activity on the pS2 promoter is considerably enhanced in the presence of all three members of the steroid receptor coactivator family but is completely abolished on treatment with the synthetic estrogen diethylstilbestrol, a recently described inhibitor of ERR function. Finally, we demonstrate that ERRalpha is the major isoform expressed in human breast cancer cell lines and that diethylstilbestrol can inhibit the growth of both ER-positive and -negative cell lines. Taken together, these results demonstrate that estrogen-inducible genes such as pS2 can be ERR targets and suggest that pharmacological modulation of ERRalpha activity may have therapeutic value in the treatment of breast cancer.
The orphan nuclear receptor small heterodimer partner (SHP; NR0B2) interacts with a wide array of nuclear receptors and represses their transcriptional activity. SHP expression is regulated by several other members of the nuclear receptor superfamily, including the orphan receptors SF-1 and LRH-1, and the bile acid receptor FXR. We have found that the SHP promoter is also activated by the estrogen receptor-related receptor γ (ERRγ) but not the related ERRα and ERRβ isoforms. SHP and ERRγ mRNAs are coexpressed in several tissues, including pancreas, kidney, and heart, confirming the potential relevance of this transactivation. ERRγ transactivation is dependent on only one of five previously characterized DNA-binding sites for SF-1, and this element differs from previously reported ERR response elements. However, treatment with the histone deacetylase inhibitor trichostatin A significantly increased ERRα and ERRβ activity on this element indicating that the lack of activity of ERRα and -β may depend on their association with co-repressor in vivo. Furthermore, using protease sensitivity assays on DNA bound receptors it was demonstrated that DNA sequence of different response elements may cause allosteric modulation of ERR proteins, which in turn may be responsible for the differential activities of these receptors on different response elements. SHP inhibits ERRγ transactivation and physically interacts with all three members of ERR subfamily, as demonstrated by both yeast two-hybrid and biochemical assays. As with other SHP targets, this interaction is dependent on the AF-2 coactivator-binding site of ERRγ and the previously described N-terminal receptor interaction domain of SHP. Several recently described SHP mutations associated with moderate obesity in humans block the inhibition of ERRγ activity. Overall, these results identify a new autoregulatory loop controlling SHP gene expression and significantly extend the potential functional roles of the three ERRs.
The transcriptional coactivator PPARγ coactivator-1α (PGC-1α) has been characterized as a broad regulator of cellular energy metabolism. Although PGC-1α functions through many transcription factors, the PGC-1α partners identified to date are unlikely to account for all of its biologic actions. The orphan nuclear receptor estrogen-related receptor α (ERRα) was identified in a yeast two-hybrid screen of a cardiac cDNA library as a novel PGC-1α-binding protein. ERRα was implicated previously in regulating the gene encoding medium-chain acyl-CoA dehydrogenase (MCAD), which catalyzes the initial step in mitochondrial fatty acid oxidation. The cardiac perinatal expression pattern of ERRα paralleled that of PGC-1α and MCAD. Adenoviral-mediated ERRα overexpression in primary neonatal cardiac mycoytes induced endogenous MCAD expression. Furthermore, PGC-1α enhanced the transactivation of reporter plasmids containing an estrogen response element or the MCAD gene promoter by ERRα and the related isoform ERRγ. In vitro binding experiments demonstrated that ERRα interacts with PGC-1α via its activation function-2 homology region. Mutagenesis studies revealed that the LXXLL motif at amino acid position 142-146 of PGC-1α (L2), necessary for PGC-1α interactions with other nuclear receptors, is not required for the PGC-1α-ERRα interaction. Rather, ERRα binds PGC-1α primarily through a Leu-rich motif at amino acids 209-213 (Leu-3) and utilizes additional LXXLL-containing domains as accessory binding sites. Thus, the PGC-1α-ERRα interaction is distinct from that of other nuclear receptor PGC-1α partners, including PPARα, hepatocyte nuclear factor-4α, and estrogen receptor α. These results identify ERRα and ERRγ as novel PGC-1α interacting proteins, implicate ERR isoforms in the regulation of mitochondrial energy metabolism, and suggest a potential mechanism whereby PGC-1α selectively binds transcription factor partners.
The estrogen-related receptor alpha (ERRalpha) is one of the first orphan nuclear receptors identified. Still, we know little about the mechanisms that regulate its expression and its activity. In this study, we show that the transcriptional coactivator PGC-1, which is implicated in the control of energy metabolism, regulates ERRalpha at two levels. First, PGC-1 induces the expression of ERRalpha. Consistent with this induction, levels of ERRalpha mRNA in vivo are highest in PGC-1 expressing tissues, such as heart, kidney, and muscle, and up-regulated in response to signals that induce PGC-1, such as exposure to cold. Second, PGC-1 interacts physically with ERRalpha and enables it to activate transcription. Strikingly, we find that PGC-1 converts ERRalpha from a factor with little or no transcriptional activity to a potent regulator of gene expression, suggesting that ERRalpha is not a constitutively active nuclear receptor but rather one that is regulated by protein ligands, such as PGC-1. Our findings suggest that the two proteins act in a common pathway to regulate processes relating to energy metabolism. In support of this hypothesis, adenovirus-mediated delivery of small interfering RNA for ERRalpha, or of PGC-1 mutants that interact selectively with different types of nuclear receptors, shows that PGC-1 can induce the fatty acid oxidation enzyme MCAD (medium-chain acyl-coenzyme A dehydrogenase) in an ERRalpha-dependent manner.
Circadian gene expression has been demonstrated in many tissues and involves both positive and negative regulatory loops. The potential interferences of circadian rhythmicity with other well-known biologic rhythms, such as the ovarian cycle, at least in part controlled by estrogens, has not been questioned. The estrogen receptor-related receptor (ERR) is an orphan nuclear receptor that is widely expressed in estrogen-responsive tissues such as liver, uterus and bone. In addition, expression of the ERR gene has been proposed to be transcriptionally controlled by estrogens in the uterus. Here we show that the expression of ERR displays a circadian rhythmicity in liver, bone and uterus. This is in contrast to other uterine estrogen-regulated genes. Analysis of clock/clock mutant mice shows that ERR is an output gene of the circadian clock oscillator. The expression of clock-control genes, such as Bmal1 and Rev-erb, also displays diurnal oscillations in the uterus, but not in bone. In this tissue, however, Per2 displayed a rhythmic expression, altogether suggesting unconventional loops in the regulation of circadian rhythm in bone.
The identification of regulatory regions is one of the most important and challenging problems toward the functional annotation of the human genome. In higher eukaryotes, transcription-factor (TF) binding sites are often organized in clusters called cis-regulatory modules (CRM). While the prediction of individual TF-binding sites is a notoriously difficult problem, CRM prediction has proven to be somewhat more reliable. Starting from a set of predicted binding sites for more than 200 TF families documented in Transfac, we describe an algorithm relying on the principle that CRMs generally contain several phylogenetically conserved binding sites for a few different TFs. The method allows the prediction of more than 118,000 CRMs within the human genome. A subset of these is shown to be bound in vivo by TFs using ChIP-chip. Their analysis reveals, among other things, that CRM density varies widely across the genome, with CRM-rich regions often being located near genes encoding transcription factors involved in development. Predicted CRMs show a surprising enrichment near the 3 end of genes and in regions far from genes. We document the tendency for certain TFs to bind modules located in specific regions with respect to their target genes and identify TFs likely to be involved in tissue-specific regulation. The set of predicted CRMs, which is made available as a public database called PReMod (http://genomequebec.mcgill.ca/PReMod), will help analyze regulatory mechanisms in specific biological systems. [Supplemental material is available online at www.genome.org.]
Selective estrogen receptor modulators (SERMs) are synthetic molecules that exhibit tissue-specific activities. 4-hydroxytamoxifen (OHT) is a first generation SERM that functions as an antagonist in breast cancer cells but displays estrogen-like activities in the uterus and bone. The estrogen-receptor-related receptors (ERR) α, β and γ are orphan members of the superfamily of nuclear receptors. While the ERRs do not respond to natural estrogens, these receptors recognize the estrogen response element and have been shown to activate and repress gene expression in the absence of exogenously added ligand. Here we show that OHT disrupts the interaction between the orphan estrogen-receptor-related (ERR) receptors β and γ and a coregulator protein and abolishs the constitutive transcriptional activity of these receptors in transient transfection assays. In contrast, OHT has no effect on coregulator/ERRα interaction or its transcriptional activity. These results demonstrate the existence of a novel nuclear receptor-based pharmacological pathway that may contribute to the tissue-specific activities of OHT.
I. Introduction II. Nuclear Receptors: General Concepts A. Anatomy of nuclear receptors B. Mechanisms of action III. Orphan Nuclear Receptors A. Definition B. Nomenclature C. Structural and functional diversity IV. Novel Hormone Response Systems: RXR and Its Heterodimeric Partners A. RXR: rexinoids B. PPAR: multiple ligands, multiple functions C. PXR: pregnanes, xenobiotic compounds, and benzoate derivatives D. CAR (constitutive androstane receptor): androstanes and phenobarbital E. LXR: control of cholesterol metabolism by oxysterols F. FXR: bile acids receptor V. Orphans in Search of a Home A. HNF4: diabetes and possible regulation by acyl-coenzyme A (CoA) thioesters B. FTZ-F1: steroidogenesis and sexual development C. Rev-Erb: singular members of the superfamily D. ROR: neuron development and T cell selection E. TR2: the testis receptors F. TLX: forebrain development G. COUP-TF: neurogenesis, angiogenesis, and heart development H. ERR: placenta development and control of lipid metabolism I. NGFI-B: hyp...
The bone fragility and increased fracture risk associated with osteoporosis in post-menopausal women is a major public health concern. Current treatments for osteoporosis relying on hormone replacement therapies are suspected to have an association with increased breast cancer risk, highlighting the need for identifying new potential targets in bone. Recent data suggest that the estrogen-related receptor (ERR)α, an orphan nuclear receptor, represses osteoblast differentiation, and that its deletion in knockout mouse models results in increased mineral density. Furthermore, modulation of ERRα activity reduces proliferation and tumorigenesis of breast cancer cells. These results indicated that inhibition of ERRα might provide a treatment for osteoporosis without displaying adverse effects in breast cancer. This review focuses on the role of the ERR receptors, and in particular ERRα, in the differentiation of bone precursor cells and its consequences on bone homeostasis, and discusses the possible grounds for the discrepancies reported in the literature.
Nuclear receptors are involved in a myriad of physiological processes, responding to ligands and binding to DNA at sequence-specific cis-regulatory elements. This binding occurs in the context of chromatin, a critical factor in regulating eukaryotic transcription. Recent high-throughput assays have examined nuclear receptor action genome-wide, advancing our understanding of receptor binding to regulatory elements. Here, we discuss current knowledge of genome-wide response element occupancy by receptors and the function of transcription factor networks in regulating nuclear receptor action. We highlight emerging roles for the epigenome, chromatin remodeling, histone modification, histone variants and long-range chromosomal interactions in nuclear receptor binding and receptor-dependent gene regulation. These mechanisms contribute importantly to the action of nuclear receptors in health and disease.
The biological significance of interactions of nuclear proteins with DNA in the context of gene expression, cell differentiation, or disease has immensely been enhanced by the advent of chromatin immunoprecipitation (ChIP). ChIP is a technique whereby a protein of interest is selectively immunoprecipitated from a chromatin preparation to determine the DNA sequences associated with it. ChIP has been widely used to map the localization of post-translationally modified histones, histone variants, transcription factors, or chromatin-modifying enzymes on the genome or on a given locus. In spite of its power, ChIP has for a long time remained a cumbersome procedure requiring large number of cells. These limitations have sparked the development of modifications to shorten the procedure, simplify the sample handling, and make the ChIP amenable to small number of cells. In addition, the combination of ChIP with DNA microarray, paired-end ditag, and high-throughput sequencing technologies has in recent years enabled the profiling of histone modifications and transcription factor occupancy on a genome-wide scale. This review highlights the variations on the theme of the ChIP assay, the various detection methods applied downstream of ChIP, and examples of their application.
Estrogen-related receptors (ERR) are orphan members of the nuclear receptor superfamily most closely related to estrogen receptors (ER). Although ERalpha is a successful target for treating breast cancer, there remains an unmet medical need especially for estrogen-independent breast cancer. Although estradiol is not an ERR ligand, ER and ERR share many commonalities and overlapping signaling pathways. An endogenous ERR ligand has not been identified; however, novel synthetic ERRalpha subtype-specific antagonists have started to emerge. In particular, we recently identified a novel compound, N-[(2Z)-3-(4,5-dihydro-1,3-thiazol-2-yl)-1,3-thiazolidin-2-yl idene]-5H dibenzo[a,d][7]annulen-5-amine (termed compound A) that acts specifically as an ERRalpha antagonist. Here, we show that compound A inhibited cell proliferation in ERalpha-positive (MCF-7 and T47D) and ERalpha-negative (BT-20 and MDA-MD-231) breast cancer cell lines. Furthermore, we report the differential expression of 83 genes involved in ERRalpha signaling in MCF-7 and BT-20 breast cancer cell lines. We show that compound A slowed tumor growth in MCF-7 and BT-20 mouse xenograft models, and displayed antagonistic effects on the uterus. Furthermore, a subset of genes involved in ERRalpha signaling in vitro were evaluated and confirmed in vivo by studying uterine gene expression profiles from xenograft mice. These results suggest for the first time that inhibition of ERRalpha signaling via a subtype-specific antagonist may be an effective therapeutic strategy for ER-positive and ER-negative breast cancers.
Estrogen receptor related receptor (ERR)alpha was one of the first identified (1988) orphan nuclear receptors. Many of the orphan receptors identified after ERRalpha were deorphanized in a timely manner and appreciated as key transcriptional regulators of metabolic pathways. ERRalpha, however, remains an orphan. Nevertheless, recent studies have defined regulatory mechanisms and transcriptional targets of ERRalpha, allowing this receptor to join ranks with other nuclear receptors that control metabolism. Notably, mice lacking ERRalpha show defects when challenged with stressors that require a 'shift of gears' in energy metabolism, such as exposure to cold, cardiac overload or infection. These findings establish the importance of ERRalpha for adaptive energy metabolism, and suggest that strategies targeting ERRalpha may be useful in fighting metabolic diseases.
Transcriptional control of cellular energy metabolic pathways is achieved by the coordinated action of numerous transcription factors and associated coregulators. Several members of the nuclear receptor superfamily have been shown to play important roles in this process because they can translate hormonal, nutrient, and metabolite signals into specific gene expression networks to satisfy energy demands in response to distinct physiological cues. Estrogen-related receptor (ERR) alpha, ERRbeta, and ERRgamma are nuclear receptors that have yet to be associated with a natural ligand and are thus considered as orphan receptors. However, the transcriptional activity of the ERRs is exquisitely sensitive to the presence of coregulatory proteins known to be essential for the control of energy homeostasis, and for all intents and purposes, these coregulators function as protein ligands for the ERRs. In particular, functional genomics and biochemical studies have shown that ERRalpha and ERRgamma operate as the primary conduits for the activity of members of the family of PGC-1 coactivators. As transcription factors, the ERRs control vast gene networks involved in all aspects of energy homeostasis, including fat and glucose metabolism as well as mitochondrial biogenesis and function. Phenotypic analyses of knockout mouse models have shown that all three ERRs are indispensable for proper development and/or survival of the organism when subjected to a variety of physiological challenges. The focus of this review is on the recent and rapid advances in understanding the functions of the ERRs in regulating bioenergetic pathways, with an emphasis on their roles in the specification of energetic properties required for cell- and tissue-specific functions.
Members of the nuclear hormone receptor gene family of transcription factors have been shown to be expressed in characteristic patterns during mouse organogenesis and postnatal development. Using an RT-PCR based screening assay, we have identified nuclear receptors expressed in embryonal carcinoma stem cells. One of the cDNAs characterized, mERR-2, was found to be expressed exclusively during a narrow developmental window in trophoblast progenitor cells between days 6.5 and 7.5 post coitum (p.c.). From 8.5 days p.c. and onwards, the mERR-2 gene activity evaded detection as analysed by in situ hybridization. We also show that the mERR-2 gene product and the estrogen receptor share a common target DNA-sequence recognition specificity unique among members of the gene family. Furthermore, efficient homodimerization and DNA-binding of the orphan receptor mERR-2 was found to be dependent on interaction with the heat shock protein 90, a molecular chaperone hitherto recognized to interact only with the steroid hormone receptor subgroup of nuclear receptors. Based on our results we suggest that the mouse orphan receptor mERR-2 has the potential to regulate overlapping gene networks with the estrogen receptor and may participate in signal transduction pathways during a short developmental period coinciding with the formation of the chorion.
Classical endocrine studies have shown that steroid hormones are required for the maintenance of pregnancy and placental viability. The oestrogen-receptor-related receptor beta (ERR-beta) is an orphan member of the superfamily of nuclear hormone receptors. Although ERR-beta is homologous to the oestrogen receptor and binds the oestrogen response element, it is not activated by oestrogens. Expression of ERR-beta during embryogenesis defines a subset of extra-embryonic ectoderm that subsequently forms the dome of the chorion, suggesting that ERR-beta may be involved in early placental development. Homozygous mutant embryos generated by targeted disruption of the Estrrb gene have severely impaired placental formation, and die at 10.5 days post-coitum. The mutants display abnormal chorion development associated with an overabundance of trophoblast giant cells and a severe deficiency of diploid trophoblast. The phenotype can be rescued by aggregation of Estrrb mutant embryos with tetraploid wild-type cells, which contribute exclusively to extra-embryonic tissues. Our results indicate that ERR-beta has an important role in early placentation, and suggest that an inductive signal originating from or modified by the chorion is required for normal trophoblast proliferation and differentiation.
The estrogen-related receptors (ERR alpha, ERR beta, and ERR gamma) form a family of orphan nuclear receptors that share significant amino acid identity with the estrogen receptors, but for which physiologic roles remain largely unknown. By using a peptide sensor assay, we have identified the stilbenes diethylstilbestrol (DES), tamoxifen (TAM), and 4-hydroxytamoxifen (4-OHT) as high-affinity ligands for ERR gamma. In direct binding assays, 4-OHT had a K(d) value of 35 nM, and both DES and TAM displaced radiolabeled 4-OHT with K(i) values of 870 nM. In cell-based assays, 4-OHT binding caused a dissociation of the complex between ERR gamma and the steroid receptor coactivator-1, and led to an inhibition of the constitutive transcriptional activity of ERR gamma. ERR alpha did not bind 4-OHT, but replacing a single amino acid predicted to be in the ERR alpha ligand-binding pocket with the corresponding ERR gamma residue allowed high-affinity 4-OHT binding. These results demonstrate the existence of high-affinity ligands for the ERR family of orphan receptors, and identify 4-OHT as a molecule that can regulate the transcriptional activity of ERR gamma.
Selective estrogen receptor modulators (SERMs) are synthetic molecules that exhibit tissue-specific activities. 4-hydroxytamoxifen (OHT) is a first generation SERM that functions as an antagonist in breast cancer cells but displays estrogen-like activities in the uterus and bone. The estrogen-receptor-related receptors (ERR) alpha, beta and gamma are orphan members of the superfamily of nuclear receptors. While the ERRs do not respond to natural estrogens, these receptors recognize the estrogen response element and have been shown to activate and repress gene expression in the absence of exogenously added ligand. Here we show that OHT disrupts the interaction between the orphan estrogen-receptor-related (ERR) receptors beta and gamma and a coregulator protein and abolishes the constitutive transcriptional activity of these receptors in transient transfection assays. In contrast, OHT has no effect on coregulator/ERR alpha interaction or its transcriptional activity. These results demonstrate the existence of a novel nuclear receptor-based pharmacological pathway that may contribute to the tissue-specific activities of OHT.
Transcription factors are key regulatory proteins that can influence the expression of hundreds of genes in response to a particular environmental condition or internal cue. The collective set of genes regulated by a transcription factor therefore defines the state of a cell and can determine cell fate. Among the 6200 predicted proteins in the yeast Saccharomyces cerevisiae, there are about 300 transcription factors. Approximately 85% of the yeast transcription factors have been characterized to some extent and some of these are known to play a critical role in cell cycle initiation, pheromone response, mating type switching, pseudohyphal growth, and nutrient and stress response. This chapter develops an approach in yeast that will comprehensively identify genomic sequences directly bound by transcription factors. This approach has been used to successfully identify targets of the yeast transcription factors SBF and MBF. Briefly, protein-DNA complexes are fixed in vivo with formaldehyde and lysed, and the lysate is sonicated to shear DNA. The transcription factor of interest is purified by immunoprecipitation; the associated DNA is extracted and then amplified and labeled for hybridization to a yeast intergenic array. Two important reagents for this method are specific immunoprecipitating antibodies and a yeast intergenic microarray.
Estrogens control a variety of physiological and disease-linked processes, most notably reproduction, bone remodeling and breast cancer, and their effects are transduced through classic unclear receptors referred to as estrogen receptor-alpha (ER alpha) and ER beta. Recent results obtained using the estrogen-related receptors (ERR alpha, -beta and -gamma), a subfamily of orphan nuclear receptors closely related to the ERs, have shown that the ERRs share target genes, coregulatory proteins, ligands and sites of action with the ERs. In addition, the ERRs can actively influence the estrogenic response, suggesting that pharmacological modulation of ERR activity will be clinically useful to prevent and/or treat a variety of conditions related to women's health.