Glucocorticoid Receptor β (GRβ): Beyond Its Dominant-Negative Function

Functional relevance of MMP2 promoter variants in gallbladder cancer: A case-control study in an Eastern Indian Population

Gallbladder cancer (GBC) is a prevalent and deadly form of bile duct cancer, associated with poor prognosis. This study aimed to investigate the genetic factors contributing to the high incidence of GBC in certain geographical regions, particularly in the Northern and Eastern parts of India. The present case-control study focused on MMP2, a gene involved in tumor progression and metastasis, as a potential candidate in GBC pathogenesis. We scanned MMP2 promoter for twelve SNPs using Sanger's sequencing and carried out a case-control study in 300 cases and 300 control samples. We found five rare variants (rs1961998763, rs1961996235, rs1391392808, rs1488656253, and rs17859816) and one nonpolymorphic SNP (rs17859817). Our results revealed a significant association between GBC and MMP2 promoter SNPs, rs243865 (Allelic-Padjusted = 0.0353) and g.55477735G > A (Allelic-Padjusted = 9.22E-05). Moreover, the haplotype "C-C-A-C-C" exhibited a significant association with GBC (P = 4.23E-05). Genotype-phenotype correlation for variant rs243865, in the GBC patient tissue samples, established that 'T' risk allele carriers had higher expression levels of MMP2. Additionally, luciferase reporter assay in HEK293T cells revealed the probable regulatory role of rs243865 variant allele 'T' in MMP2 expression. Our study uncovers the association of MMP2 promoter SNPs with GBC and their role in regulating its expression.

Mineralocorticoid Receptor Antagonism Reduces Inflammatory Pain Measures in Mice Independent of the Receptors on Sensory Neurons

Corticosteroids are commonly used in the treatment of inflammatory low back pain, and their nominal target is the glucocorticoid receptor (GR) to relieve inflammation. They can also have similar potency at the mineralocorticoid receptor (MR). The MR has been shown to be widespread in rodent and human dorsal root ganglia (DRG) neurons and non-neuronal cells, and when MR antagonists are administered during a variety of inflammatory pain models in rats, pain measures are reduced. In this study we selectively knockout (KO) the MR in sensory neurons to determine the role of MR in sensory neurons of the mouse DRG in pain measures as MR antagonism during the local inflammation of the DRG (LID) pain model. We found that MR antagonism using eplerenone reduced evoked mechanical hypersensitivity during LID, but MR KO in paw-innervating sensory neurons only did not. This could be a result of differences between prolonged (MR KO) versus acute (drug) MR block or an indicator that non-neuronal cells in the DRG are driving the effect of MR antagonists. MR KO unmyelinated C neurons are more excitable under normal and inflamed conditions, while MR KO does not affect excitability of myelinated A cells. MR KO in sensory neurons causes a reduction in overall GR mRNA but is protective against reduction of the anti-inflammatory GRα isoform during LID. These effects of MR KO in sensory neurons expanded our understanding of MR's functional role in different neuronal subtypes (A and C neurons), and its interactions with the GR.

Context is key: glucocorticoid receptor and corticosteroid therapeutics in outcomes after traumatic brain injury

Traumatic brain injury (TBI) is a global health burden, and survivors suffer functional and psychiatric consequences that can persist long after injury. TBI induces a physiological stress response by activating the hypothalamic-pituitary-adrenal (HPA) axis, but the effects of injury on the stress response become more complex in the long term. Clinical and experimental evidence suggests long lasting dysfunction of the stress response after TBI. Additionally, pre- and post-injury stress both have negative impacts on outcome following TBI. This bidirectional relationship between stress and injury impedes recovery and exacerbates TBI-induced psychiatric and cognitive dysfunction. Previous clinical and experimental studies have explored the use of synthetic glucocorticoids as a therapeutic for stress-related TBI outcomes, but these have yielded mixed results. Furthermore, long-term steroid treatment is associated with multiple negative side effects. There is a pressing need for alternative approaches that improve stress functionality after TBI. Glucocorticoid receptor (GR) has been identified as a fundamental link between stress and immune responses, and preclinical evidence suggests GR plays an important role in microglia-mediated outcomes after TBI and other neuroinflammatory conditions. In this review, we will summarize GR-mediated stress dysfunction after TBI, highlighting the role of microglia. We will discuss recent studies which target microglial GR in the context of stress and injury, and we suggest that cell-specific GR interventions may be a promising strategy for long-term TBI pathophysiology.

Glucocorticoid Receptor Gene (NR3C1) Polymorphisms and Metabolic Syndrome: Insights from the Mennonite Population

The regulation of the hypothalamic-pituitary-adrenal (HPA) axis is associated with polymorphisms and the methylation degree of the glucocorticoid receptor gene (NR3C1) and is potentially involved in the development of metabolic syndrome (MetS). In order to evaluate the association between MetS with the polymorphisms, methylation, and gene expression of the NR3C1 in the genetically isolated Brazilian Mennonite population, we genotyped 20 NR3C1 polymorphisms in 74 affected (MetS) and 138 unaffected individuals without affected first-degree relatives (Co), using exome sequencing, as well as five variants from non-exonic regions, in 70 MetS and 166 Co, using mass spectrometry. The methylation levels of 11 1F CpG sites were quantified using pyrosequencing (66 MetS and 141 Co), and the NR3C1 expression was evaluated via RT-qPCR (14 MetS and 25 Co). Age, physical activity, and family environment during childhood were associated with MetS. Susceptibility to MetS, independent of these factors, was associated with homozygosity for rs10482605*C (OR = 4.74, pcorr = 0.024) and the haplotype containing TTCGTTGATT (rs3806855*T_ rs3806854*T_rs10482605*C_rs10482614*G_rs6188*T_rs258813*T_rs33944801*G_rs34176759*A_rs17209258*T_rs6196*T, OR = 4.74, pcorr = 0.048), as well as for the CCT haplotype (rs41423247*C_ rs6877893*C_rs258763*T), OR = 6.02, pcorr = 0.030), but not to the differences in methylation or gene expression. Thus, NR3C1 polymorphisms seem to modulate the susceptibility to MetS in Mennonites, independently of lifestyle and early childhood events, and their role seems to be unrelated to DNA methylation and gene expression.

Screening of Anti-Inflammatory Activity and Metabolomics Analysis of Endophytic Fungal Extracts; Identification and Characterization of Perylenequinones and Terpenoids from the Interesting Active Alternaria Endophyte

Patients suffering from inflammatory chronic diseases are classically treated with anti-inflammatory drugs but unfortunately are highly susceptible to becoming resistant to their treatment. Finding new drugs is therefore crucial and urgent and research on endophytic fungi is a promising way forward. Endophytic fungi are microorganisms that colonize healthy plants and live within their intercellular tissues. They are able to produce a large variety of secondary metabolites while allowing their host to stay healthy. A number of these molecules are endowed with antioxidant or antimicrobial as well as cytotoxic properties, making them very interesting/promising in the field of human therapy. The aim of our study was to investigate whether extracts from five endophytic fungi isolated from plants are endowed with anti-inflammatory activity. Extracts of the endophytic fungi Alternaria alternata from Calotropis procera leaves and Aspergillus terreus from Trigonella foenum-graecum seeds were able to counteract the lipopolysaccharide (LPS) pro-inflammatory effect on THP-1 cells differentiated into macrophages. Moreover, they were able to induce an anti-inflammatory state, rendering them less sensitive to the LPS pro-inflammatory stimulus. Taken together, these results show that these both endophytic fungi could be interesting alternatives to conventional anti-inflammatory drugs. To gain more detailed knowledge of their chemical richness, phytochemical analysis of the ethyl acetate extracts of the five endophytic fungi studied was performed using HPTLC, GC-MS and LC-MS with the Global Natural Products Social (GNPS) platform and the MolNetEnhancer tool. A large family of metabolites (carboxylic acids and derivatives, steroid derivatives, alkaloids, hydroxyanthraquinones, valerolactones and perylenequinones) were detected. The purification of endophytic fungus extract of Alternaria alternate, which diminished TNF-α production of 66% at 20 µg/mL, incubated one hour before LPS addition, led to the characterization of eight pure compounds. These molecules are altertoxins I, II, III, tricycloalternarenes 3a, 1b, 2b, anthranilic acid, and o-acetamidobenzoic acid. In the future, all these pure compounds will be evaluated for their anti-inflammatory activity, while altertoxin II has been shown in the literature as the most active mycotoxin in terms of anti-inflammatory activity.

Biased regulation of glucocorticoid receptors signaling

Glucocorticoids (GCs), steroid hormones that depend on glucocorticoid receptor (GR) binding for their action, are essential for regulating numerous homeostatic functions in the body.GR signals are biased, that is, GR signals are various in different tissue cells, disease states and ligands. This biased regulation of GR signaling appears to depend on ligand-induced metameric regulation, protein post-translational modifications, assembly at response elements, context-specific assembly (recruitment of co-regulators) and intercellular differences. Based on the bias regulation of GR, selective GR agonists and modulators (SEGRAMs) were developed to bias therapeutic outcomes toward expected outcomes (e.g., anti-inflammation and immunoregulation) by influencing GR-mediated gene expression. This paper provides a review of the bias regulation and mechanism of GR and the research progress of drugs.

The Biologist's Guide to the Glucocorticoid Receptor's Structure

The glucocorticoid receptor α (GRα) is a member of the nuclear receptor superfamily and functions as a glucocorticoid (GC)-responsive transcription factor. GR can halt inflammation and kill off cancer cells, thus explaining the widespread use of glucocorticoids in the clinic. However, side effects and therapy resistance limit GR's therapeutic potential, emphasizing the importance of resolving all of GR's context-specific action mechanisms. Fortunately, the understanding of GR structure, conformation, and stoichiometry in the different GR-controlled biological pathways is now gradually increasing. This information will be crucial to close knowledge gaps on GR function. In this review, we focus on the various domains and mechanisms of action of GR, all from a structural perspective.

CmPn/CmP Signaling Networks in the Maintenance of the Blood Vessel Barrier

Cerebral cavernous malformations (CCMs) arise when capillaries within the brain enlarge abnormally, causing the blood-brain barrier (BBB) to break down. The BBB serves as a sophisticated interface that controls molecular interactions between the bloodstream and the central nervous system. The neurovascular unit (NVU) is a complex structure made up of neurons, astrocytes, endothelial cells (ECs), pericytes, microglia, and basement membranes, which work together to maintain blood-brain barrier (BBB) permeability. Within the NVU, tight junctions (TJs) and adherens junctions (AJs) between endothelial cells play a critical role in regulating the permeability of the BBB. Disruptions to these junctions can compromise the BBB, potentially leading to a hemorrhagic stroke. Understanding the molecular signaling cascades that regulate BBB permeability through EC junctions is, therefore, essential. New research has demonstrated that steroids, including estrogens (ESTs), glucocorticoids (GCs), and metabolites/derivatives of progesterone (PRGs), have multifaceted effects on blood-brain barrier (BBB) permeability by regulating the expression of tight junctions (TJs) and adherens junctions (AJs). They also have anti-inflammatory effects on blood vessels. PRGs, in particular, have been found to play a significant role in maintaining BBB integrity. PRGs act through a combination of its classic and non-classic PRG receptors (nPR/mPR), which are part of a signaling network known as the CCM signaling complex (CSC). This network couples both nPR and mPR in the CmPn/CmP pathway in endothelial cells (ECs).

NR3C1 rs6198 Variant May Be Involved in the Relationship of Graves' Disease with Stressful Events

Although stressful events are known to trigger Graves' disease (GD), the mechanisms involved in this process are not well understood. The NR3C1 gene, encoding for the glucocorticoid receptor (GR), presents single nucleotide polymorphisms (SNPs) that are associated with stress-related diseases. To investigate the relationship between NR3C1 SNPs, GD susceptibility, and clinical features, we studied 792 individuals, including 384 patients, among which 209 presented with Graves' orbitopathy (GO), and 408 paired healthy controls. Stressful life events were evaluated in a subset of 59 patients and 66 controls using the IES-R self-report questionnaire. SNPs rs104893913, rs104893909, and rs104893911 appeared at low frequencies and presented similar profiles in patients and controls. However, variant forms of rs6198 were rarer in GD patients, suggesting a protective effect. Stressful events were more common in patients than controls, and were reported to have clearly occurred immediately before the onset of GD symptoms in 23 cases. However, no association was found between these events and rs6198 genotypes or GD/GO characteristics. We suggest that the NR3C1 rs6198 polymorphism may be an important protective factor against GD, but its relationship with stressful events needs further investigation.

Glucocorticoid Receptor and Ovarian Cancer: From Biology to Therapeutic Intervention

Ovarian cancer (OC) is the leading cause of death from gynecological malignancies worldwide. Fortunately, recent advances in OC biology and the discovery of novel therapeutic targets have led to the development of novel therapeutic agents that may improve the outcome of OC patients. The glucocorticoid receptor (GR) is a ligand-dependent transcriptional factor known for its role in body stress reactions, energy homeostasis and immune regulation. Notably, evidence suggests that GR may play a relevant role in tumor progression and may affect treatment response. In cell culture models, administration of low levels of glucocorticoids (GCs) suppresses OC growth and metastasis. Conversely, high GR expression has been associated with poor prognostic features and long-term outcomes in patients with OC. Moreover, both preclinical and clinical data have shown that GR activation impairs the effectiveness of chemotherapy by inducing the apoptotic pathways and cell differentiation. In this narrative review, we summarize data related to the function and role of GR in OC. To this aim, we reorganized the controversial and fragmented data regarding GR activity in OC and herein describe its potential use as a prognostic and predictive biomarker. Moreover, we explored the interplay between GR and BRCA expression and reviewed the latest therapeutic strategies such as non-selective GR antagonists and selective GR modulators to enhance chemotherapy sensitivity, and to finally provide new treatment options in OC patients.

Context-Dependent Role of Glucocorticoid Receptor Alpha and Beta in Breast Cancer Cell Behaviour

Background. The dual role of GCs has been observed in breast cancer; however, due to many concomitant factors, GR action in cancer biology is still ambiguous. In this study, we aimed to unravel the context-dependent action of GR in breast cancer. Methods. GR expression was characterized in multiple cohorts: (1) 24,256 breast cancer specimens on the RNA level, 220 samples on the protein level and correlated with clinicopathological data; (2) oestrogen receptor (ER)-positive and -negative cell lines were used to test for the presence of ER and ligand, and the effect of the GRβ isoform following GRα and GRβ overexpression on GR action, by in vitro functional assays. Results. We found that GR expression was higher in ER- breast cancer cells compared to ER+ ones, and GR-transactivated genes were implicated mainly in cell migration. Immunohistochemistry showed mostly cytoplasmic but heterogenous staining irrespective of ER status. GRα increased cell proliferation, viability, and the migration of ER- cells. GRβ had a similar effect on breast cancer cell viability, proliferation, and migration. However, the GRβ isoform had the opposite effect depending on the presence of ER: an increased dead cell ratio was found in ER+ breast cancer cells compared to ER- ones. Interestingly, GRα and GRβ action did not depend on the presence of the ligand, suggesting the role of the "intrinsic", ligand-independent action of GR in breast cancer. Conclusions. Staining differences using different GR antibodies may be the reason behind controversial findings in the literature regarding the expression of GR protein and clinicopathological data. Therefore, caution in the interpretation of immunohistochemistry should be applied. By dissecting the effects of GRα and GRβ, we found that the presence of the GR in the context of ER had a different effect on cancer cell behaviour, but independently of ligand availability. Additionally, GR-transactivated genes are mostly involved in cell migration, which raises GR's importance in disease progression.

[Association of the structure of the glucocorticoid receptor and single nucleotide NR3C1 gene polymorphisms with metabolic disorders]

Glucocorticoid therapy is widely used in the treatment of various pathologies. Sensitivity to glucocorticoids  (GC) has a serious impact not only on the effectiveness of their action, but also on the severity of side effects, the formation of risk factors and the development  of cardiovascular diseases (CVD). Variability of sensitivity to GC causes different phenotypes and severity of metabolic disorders underlying  CVD. Among  them, one can distinguish  a decrease in muscle mass and strength, obesity, glucose and lipid metabolism impairment, and others. Glucocorticoids carry out their effects by binding to the glucocorticoid receptor (GR), and therefore this is considered a critical point in their action. This review presents data on the significance of the glucocorticoid  receptor structure, examines the main single nucleotide polymorphisms (SNP) of the NR3C1 gene associated with hypersensitivity  or relative resistance to glucocorticoids  in the context of metabolic disorders and the development of CVD. The association of the four most studied SNP of the GR gene with metabolic risks is described in detail: BclI (rs41423247), N363S (rs56149945), ER22/23EK (rs6189/rs6190), GR-9ß (rs6198). Their determination can contribute to clarifying the prognosis of both the effectiveness of GC and the development of metabolic disorders, and subsequent early correction of CVD risk factors.

TNF-α Regulates the Glucocorticoid Receptor Alpha Expression in Human Nasal Epithelial Cells Via p65-NF-κb and p38-MAPK Signaling Pathways

Background

Tumor necrosis factor (TNF)-α induces changes in the glucocorticoid receptor (GR) isoforms' expression in human nasal epithelial cells (HNECs) in chronic rhinosinusitis (CRS).

Objective

However, the underlying mechanism of TNF-α induced GR isoforms' expression in HNECs remains unclear. Here, we explored changes in inflammatory cytokines and glucocorticoid receptor alpha isoform (GRα) expression in HNECs.

Materials and Methods

To explore the expression of TNF-α in nasal polyps and nasal mucosa of CRS, fluorescence immunohistochemical analysis was employed. To investigate changes in inflammatory cytokines and GRα expression in HNECs, RT-PCR and western blotting were performed following the cells' incubation with TNF-α. Cells were pretreated with the nuclear factor-κB gene binding (NF-κB) inhibitor QNZ, the p38 inhibitor SB203580, and dexamethasone for one hour, then a TNF-α. Western blotting, RT-PCR, and immunofluorescence had been utilized for the cells' analysis and the ANOVA for the data analysis.

Results

The TNF-α fluorescence intensity was mainly distributed in nasal epithelial cells of nasal tissues. TNF-α prominently inhibited the expression of GRα mRNA from 6 to 24 h in HNECs. GRα protein was decreased from 12 to 24 h. Treatment with QNZ, SB203580, or dexamethasone inhibited the TNF-α and interleukin (IL)-6 mRNA expression and increased the GRα levels.

Conclusion

TNF-α induced changes in the GR isoforms' expression in HNECs, and it was mediated through p65-NF-κB and p38-MAPK signal transduction pathways, which could be considered a promising neutrophilic CRS treatment.

The complex challenge of antenatal steroid therapy nonresponsiveness

Antenatal steroid therapy is standard care for women at imminent risk of preterm delivery. When deliveries occur within 7 days of treatment, antenatal steroid therapy reduces the risk of neonatal death and improves preterm outcomes by exerting diverse developmental effects on the fetal organs, in particular the preterm lung and cardiovascular system. There is, however, sizable variability in antenatal steroid treatment efficacy, and an important percentage of fetuses exposed to antenatal steroid therapy do not respond sufficiently to derive benefit. Respiratory distress syndrome, for example, is a central metric of clinical trials to assess antenatal steroid outcomes. In the present analysis, we addressed the concept of antenatal steroid nonresponsiveness, and defined a failed or suboptimal response to antenatal steroids as death or a diagnosis of respiratory distress syndrome following treatment. For deliveries at 24 to 35 weeks' gestation, the number needed to treat to prevent 1 case of respiratory distress syndrome was 19 (95% confidence interval, 14-28). Reflecting gestation-dependent risk, for deliveries at >34 weeks' gestation the number needed to treat was 55 (95% confidence interval, 30-304), whereas for elective surgical deliveries at term this number was 106 (95% confidence interval, 61-421). We reviewed data from clinical and animal studies investigating antenatal steroid therapy to highlight the significant incidence of antenatal steroid therapy nonresponsiveness (ie, residual mortality or respiratory distress syndrome after treatment), and the potential mechanisms underpinning this outcome variability. The origins of this variability may be related to both the manner in which the therapy is applied (ie, the treatment regimen itself) and factors specific to the individual (ie, genetic variation, stress, infection). The primary aims of this review were: (1) to emphasize to the obstetrical and neonatal communities the extent of antenatal steroid response variability and its potential impact; (2) to propose approaches by which antenatal steroid therapy may be better applied to improve overall benefit; and (3) to stimulate further research toward the empirical optimization of this important antenatal therapy.

The Human Glucocorticoid Receptor Beta: From Molecular Mechanisms to Clinical Implications

Glucocorticoids play a fundamental role in a plethora of cellular processes and physiologic functions through binding on a ubiquitously expressed receptor, the glucocorticoid receptor (GR), which functions as a ligand-activated transcription factor influencing the transcription rate of numerous genes in a positive or negative fashion. For many years, we believed that the pleiotropic actions of glucocorticoids were mediated by a single GR protein expressed by the NR3C1 gene. Nowadays, we know that the NR3C1 gene encodes 2 main receptor isoforms, the GRα and the GRβ, through alternative splicing of the last exons. Furthermore, the alternative initiation of GR mRNA translation generates 8 distinct GRα and possibly 8 different GRβ receptor isoforms. The tremendous progress of cellular, molecular, and structural biology in association with the data explosion provided by bioinformatics have enabled a deeper understanding of the role of GRβ in cellular homeostasis. In this review article, I will provide an update on the cellular properties and functions of hGRβ and summarize the current knowledge about the evolving role of the beta isoform of glucocorticoid receptor in endocrine physiology, pathophysiology, and beyond.

Interactions between nuclear receptors glucocorticoid receptor α and peroxisome proliferator-activated receptor α form a negative feedback loop

Both nuclear receptors glucocorticoid receptor α (GRα) and peroxisome proliferator-activated receptor α (PPARα) are involved in energy and lipid metabolism, and possess anti-inflammation effects. Previous studies indicate that a regulatory loop may exist between them. In vivo and in vitro studies showed that glucocorticoids stimulate hepatic PPARα expression via GRα at the transcriptional level. This stimulation of PPARα by GRα has physiological relevance and PPARα is involved in many glucocorticoid-induced pathophysiological processes, including gluconeogenesis and ketogenesis during fasting, insulin resistance, hypertension and anti-inflammatory effects. PPARα also synergizes with GRα to promote erythroid progenitor self-renewal. As the feedback, PPARα inhibits glucocorticoid actions at pre-receptor and receptor levels. PPARα decreases glucocorticoid production through inhibiting the expression and activity of type-1 11β-hydroxysteroid dehydrogenase, which converts inactive glucocorticoids to active glucocorticoids at local tissues, and also down-regulates hepatic GRα expression, thus forming a complete and negative feedback loop. This negative feedback loop sheds light on prospective multi-drug therapeutic treatments in inflammatory diseases through a combination of glucocorticoids and PPARα agonists. This combination may potentially enhance the anti-inflammatory effects while alleviating side effects on glucose and lipid metabolism due to GRα activation. More investigations are needed to clarify the underlying mechanism and the relevant physiological or pathological significance of this regulatory loop.

Glucocorticoid Insensitivity in Asthma: The Unique Role for Airway Smooth Muscle Cells

Although most patients with asthma symptoms are well controlled by inhaled glucocorticoids (GCs), a subgroup of patients suffering from severe asthma respond poorly to GC therapy. Such GC insensitivity (GCI) represents a profound challenge in managing patients with asthma. Even though GCI in patients with severe asthma has been investigated by several groups using immune cells (peripheral blood mononuclear cells and alveolar macrophages), uncertainty exists regarding the underlying molecular mechanisms in non-immune cells, such as airway smooth cells (ASM) cells. In asthma, ASM cells are among the targets of GC therapy and have emerged as key contributors not only to bronchoconstriction but also to airway inflammation and remodeling, as implied by experimental and clinical evidence. We here summarize the current understanding of the actions/signaling of GCs in asthma, and specifically, GC receptor (GR) “site-specific phosphorylation” and its role in regulating GC actions. We also review some common pitfalls associated with studies investigating GCI and the inflammatory mediators linked to asthma severity. Finally, we discuss and contrast potential molecular mechanisms underlying the impairment of GC actions in immune cells versus non-immune cells such as ASM cells.

GR-α and GR-β mRNA levels in peripheral blood mononuclear cells of acute myelitis patients can assist in the identification of glucocorticoid sensitivity and are correlated with glucocorticoid therapeutic effect

Acute myelitis (AM) is a rare neuro-immune spinal cord disease. This study sought to explore the transcription level of glucocorticoid (GC) receptors α and β (GR-α/GR-β) in peripheral blood mononuclear cells (PBMCs) and their correlation with GC efficacy and sensitivity in AM patients. AM patients were grouped into the GC-sensitive group (N = 80) and GC-refractory group (N = 67). The GR-α and GR-β mRNA levels in PBMCs were detected. The differentiating value of GR-α, GR-β, and GR-α + GR-β on GC sensitivity and resistance in AM patients was assessed. The independent correlation between GR-α and GR-β mRNA levels and GC sensitivity in AM patients,t and the correlation between GR-α and GR-β mRNA levels and spinal function after GC treatment were analyzed. GR-α mRNA level in PBMCs of GC-refractory patients was lower than that of GC-sensitive patients, while GR-β mRNA level was higher than that of GC-sensitive patients. GR-α + GR-β mRNA had a high diagnostic value for GC sensitivity and resistance in AM patients (area under the ROC curve = 0.881, sensitivity = 79.1%, specificity = 85.0%). GR-α and GR-β mRNA levels were independently correlated with GC sensitivity. GR-α and GR-β mRNA levels were correlated with the spinal function of AM patients after GC treatment. Overall, GR-α and GR-β mRNA levels in PBMCs of AM patients can assist in the identification of GC sensitivity and are correlated with GC efficacy.

The Role of Glucocorticoid Receptor in the Pathophysiology of Pituitary Corticotroph Adenomas

Adrenocorticotropic Hormone (ACTH)-secreting pituitary adenomas are rare tumors characterized by autonomous ACTH secretion with a consequent increase in circulating cortisol levels. The resulting clinical picture is called Cushing’s disease (CD), a severe condition burdened with high morbidity and mortality. Apart from increased cortisol levels, CD patients exhibit a partial resistance to the negative glucocorticoid (GC) feedback, which is of paramount clinical utility, as the lack of suppression after dexamethasone administration is one of the mainstays for the differential diagnosis of CD. Since the glucocorticoid receptor (GR) is the main regulator of negative feedback of the hypothalamic–pituitary–adrenal axis in normal conditions, its implication in the pathophysiology of ACTH-secreting pituitary tumors is highly plausible. In this paper, we review GR function and structure and the mechanisms of GC resistance in ACTH-secreting pituitary tumors and assess the effects of the available medical therapies targeting GR on tumor growth.

Glucocorticoid Receptor β Overexpression Has Agonist-Independent Insulin-Mimetic Effects on HepG2 Glucose Metabolism

Glucocorticoids (GC) are steroids hormones that drive circulating glucose availability through gluconeogenesis in the liver. However, alternative splicing of the GR mRNA produces two isoforms, termed GRα and GRβ. GRα is the classic receptor that binds to GCs and mediates the most described actions of GCs. GRβ does not bind GCs and acts as a dominant-negative inhibitor of GRα. Moreover, GRβ has intrinsic and GRα-independent transcriptional activity. To date, it remains unknown if GRβ modulates glucose handling in hepatocytes. Therefore, the study aims to characterize the impact of GRβ overexpression on glucose uptake and storage using an in vitro hepatocyte model. Here we show that GRβ overexpression inhibits the induction of gluconeogenic genes by dexamethasone. Moreover, GRβ activates the Akt pathway, increases glucose transports mRNA, increasing glucose uptake and glycogen storage as an insulin-mimetic. Our results suggest that GRβ has agonist-independent insulin-mimetic actions in HepG2 cells.

Differential expression of genes regulated by the glucocorticoid receptor pathway in patients with pulmonary tuberculosis

AIMS

Previous studies in TB patients showed an immuno-endocrine imbalance characterized by a disease-severity associated increase in plasma levels of proinflammatory cytokines and glucocorticoids (GCs). To analyze the potential immunomodulatory effect of circulating GCs over peripheral blood mononuclear cells (PBMC) from TB patients, we investigated the expression of positively (anti-inflammatory-related genes ANXA1; FKBP51; GILZ, NFKBIA, and NFKBIB) and negatively (inflammatory genes: IL-6, IL-1β, and IFN-γ) Glucocorticoids Receptors (GR)-regulated genes. Plasma concentrations of cytokines and hormones, together with specific lymphoproliferation were also assessed.

MATERIALS AND METHODS

Gene expression was quantified by RT-qPCR, specific lymphoproliferation by ³H-thymidine incorporation, whereas plasma cytokines and hormones levels by ELISA.

KEY FINDINGS

Transcripts of ANXA1, GILZ, NFKBIB, and NFKBIA appeared significantly increased in patients, whereas FKBP51, IL-6, IL-1β, and NF-κB remained unchanged. Upon analyzing according to disease severity, mRNA levels for ANXA1 and NFKBIB were even higher in moderate and severe patients. GILZ was increased in moderate cases, with NFKBIA and IL-1 β being higher in severe ones, who also displayed increased GRβ transcripts. TB patients had reduced plasma DHEA concentrations together with increased pro and anti-inflammatory cytokines (IFN-γ, IL-6, and IL-10) cortisol and cortisol/DHEA ratio, more evident in progressive cases, in whom their PBMC also showed a decreased mycobacterial-driven proliferation. The cortisol/DHEA ratio and GRα expression were positively correlated with GR-regulated genes mainly in moderate patients.

SIGNIFICANCE

The increased expression of cortisol-regulated anti-inflammatory genes in TB patients-PBMC, predominantly in progressive disease, seems compatible with a relatively insufficient attempt to downregulate the accompanying inflammation.

Crosstalk between p38 MAPK and GR Signaling

The p38 MAPK is a signaling pathway important for cells to respond to environmental and intracellular stress. Upon activation, the p38 kinase phosphorylates downstream effectors, which control the inflammatory response and coordinate fundamental cellular processes such as proliferation, apoptosis, and differentiation. Dysregulation of this signaling pathway has been linked to inflammatory diseases and cancer. Secretion of glucocorticoids (GCs) is a classical endocrine response to stress. The glucocorticoid receptor (GR) is the primary effector of GCs and plays an important role in the regulation of cell metabolism and immune response by influencing gene expression in response to hormone-dependent activation. Its ligands, the GCs or steroids, in natural or synthetic variation, are used as standard therapy for anti-inflammatory treatment, severe asthma, autoimmune diseases, and several types of cancer. Several years ago, the GR was identified as one of the downstream targets of p38, and, at the same time, it was shown that glucocorticoids could influence p38 signaling. In this review, we discuss the role of the crosstalk between the p38 and GR in the regulation of gene expression in response to steroids and comprehend the importance and potential of this interplay in future clinical applications.

Mechanisms behind context-dependent role of glucocorticoids in breast cancer progression

Glucocorticoids (GCs), mostly dexamethasone (dex), are routinely administered as adjuvant therapy to manage side effects in breast cancer. However, recently, it has been revealed that dex triggers different effects and correlates with opposite outcomes depending on the breast cancer molecular subtype. This has raised new concerns regarding the generalized use of GC and suggested that the context-dependent effects of GCs can be taken into potential consideration during treatment design. Based on this, attention has recently been drawn to the role of the glucocorticoid receptor (GR) in development and progression of breast cancer. Therefore, in this comprehensive review, we aimed to summarize the different mechanisms behind different context-dependent GC actions in breast cancer by applying a multilevel examination, starting from the association of variants of the GR-encoding gene to expression at the mRNA and protein level of the receptor, and its interactions with other factors influencing GC action in breast cancer. The role of GCs in chemosensitivity and chemoresistance observed during breast cancer therapy is discussed. In addition, experiences using GC targeting therapeutic options (already used and investigated in preclinical and clinical trials), such as classic GC dexamethasone, selective glucocorticoid receptor agonists and modulators, the GC antagonist mifepristone, and GR coregulators, are also summarized. Evidence presented can aid a better understanding of the biology of context-dependent GC action that can lead to further advances in the personalized therapy of breast cancer by the evaluation of GR along with the conventional estrogen receptor (ER) and progesterone receptor (PR) in the routine diagnostic procedure.

Oncogenic Activity of Glucocorticoid Receptor β Is Controlled by Ubiquitination-Dependent Interaction with USP49 in Glioblastoma Cells

Previous studies have demonstrated that glucocorticoid receptor β (GRβ) functions as an oncoprotein, regulating the malignant phenotypes and stem-like cell maintaining in human glioblastoma (GBM). Of the glucocorticoid receptor (GR) isoforms, GRβ and GRα are highly homologous, though the mechanism underlying the distinct functions of these two isoforms in GBM has not been clarified. Here by establishing a carboxyl-terminal (COOH-terminal) deletion mutant, we determined that GRβ can be ubiquitinated. We also found that its COOH terminal is essential for this ubiquitination. The mutation of a lysine to arginine at residue 733 (K733R) blocked the ubiquitination of GRβ, indicating that K733 is a key site for ubiquitination. Using K733R to establish nonubiquitinated GRβ, we demonstrated that ubiquitination not only regulates the stability and nuclear translocation of GRβ, but is also a vital mechanism for its oncogenic functions in vitro and in vivo. Protein interaction assay further indicated that ubiquitin-specific protease 49 (USP49) is a GRβ-binding protein and the interaction depends on GRβ ubiquitination. USP49 knockdown resulted in a decrease of cell proliferation, invasion, and an increase of cell apoptosis. More importantly, USP49 knockdown increased ubiquitination and amplified the oncogenic effects of GRβ, confirming the decisive role of ubiquitination on GRβ carcinogenicity. Taken together, these findings established that ubiquitination is a vial process for GRβ the execution of oncogenic functions in GBM and that the K733 site is crucial for ubiquitination of GRβ. IMPLICATIONS: This work is the first identify of the activation GRβ by a single lysine point-mediated ubiquitination and proteasome degradation, which determines its oncogenic functions in GBM.

Homeostatic Regulation of Glucocorticoid Receptor Activity by Hypoxia-Inducible Factor 1: From Physiology to Clinic

Glucocorticoids (GCs) represent a well-known class of lipophilic steroid hormones biosynthesised, with a circadian rhythm, by the adrenal glands in humans and by the inter-renal tissue in teleost fish (e.g., zebrafish). GCs play a key role in the regulation of numerous physiological processes, including inflammation, glucose, lipid, protein metabolism and stress response. This is achieved through binding to their cognate receptor, GR, which functions as a ligand-activated transcription factor. Due to their potent anti-inflammatory and immune-suppressive action, synthetic GCs are broadly used for treating pathological disorders that are very often linked to hypoxia (e.g., rheumatoid arthritis, inflammatory, allergic, infectious, and autoimmune diseases, among others) as well as to prevent graft rejections and against immune system malignancies. However, due to the presence of adverse effects and GC resistance their therapeutic benefits are limited in patients chronically treated with steroids. For this reason, understanding how to fine-tune GR activity is crucial in the search for novel therapeutic strategies aimed at reducing GC-related side effects and effectively restoring homeostasis. Recent research has uncovered novel mechanisms that inhibit GR function, thereby causing glucocorticoid resistance, and has produced some surprising new findings. In this review we analyse these mechanisms and focus on the crosstalk between GR and HIF signalling. Indeed, its comprehension may provide new routes to develop novel therapeutic targets for effectively treating immune and inflammatory response and to simultaneously facilitate the development of innovative GCs with a better benefits-risk ratio.

The coupling of RACK1 with the beta isoform of the glucocorticoid receptor promotes resilience to chronic stress exposure

Several intracellular pathways that contribute to the adaptation or maladaptation to environmental challenges mediate the vulnerability and resilience to chronic stress. The activity of the hypothalamic-pituitary-adrenal (HPA) axis is fundamental for the proper maintenance of brain processes, and it is related to the functionality of the isoform alfa and beta of the glucocorticoid receptor (Gr), the primary regulator of HPA axis. Among the downstream effectors of the axis, the scaffolding protein RACK1 covers an important role in regulating synaptic activity and mediates the transcription of the neurotrophin Bdnf. Hence, by employing the chronic mild stress (CMS) paradigm, we studied the role of the Grβ-RACK1-Bdnf signaling in the different susceptibility to chronic stress exposure. We found that resilience to two weeks of CMS is paralleled by the activation of this pathway in the ventral hippocampus, the hippocampal subregion involved in the modulation of stress response. Moreover, the results we obtained in vitro by exposing SH-SY5Y cells to cortisol support the data we found in vivo. The results obtained add novel critical information about the link among Gr, RACK1 and Bdnf and the resilience to chronic stress, suggesting novel targets for the treatment of stress-related disorders, including depression.

Primary Generalized Glucocorticoid Resistance and Hypersensitivity Syndromes: A 2021 Update

Glucocorticoids are the final products of the neuroendocrine hypothalamic-pituitary-adrenal axis, and play an important role in the stress response to re-establish homeostasis when it is threatened, or perceived as threatened. These steroid hormones have pleiotropic actions through binding to their cognate receptor, the human glucocorticoid receptor, which functions as a ligand-bound transcription factor inducing or repressing the expression of a large number of target genes. To achieve homeostasis, glucocorticoid signaling should have an optimal effect on all tissues. Indeed, any inappropriate glucocorticoid effect in terms of quantity or quality has been associated with pathologic conditions, which are characterized by short-term or long-lasting detrimental effects. Two such conditions, the primary generalized glucocorticoid resistance and hypersensitivity syndromes, are discussed in this review article. Undoubtedly, the tremendous progress of structural, molecular, and cellular biology, in association with the continued progress of biotechnology, has led to a better and more in-depth understanding of these rare endocrinologic conditions, as well as more effective therapeutic management.

Acquired Glucocorticoid Resistance Due to Homologous Glucocorticoid Receptor Downregulation: A Modern Look at an Age-Old Problem

For over 70 years, the unique anti-inflammatory properties of glucocorticoids (GCs), which mediate their effects via the ligand-activated transcription factor, the glucocorticoid receptor alpha (GRα), have allowed for the use of these steroid hormones in the treatment of various autoimmune and inflammatory-linked diseases. However, aside from the onset of severe side-effects, chronic GC therapy often leads to the ligand-mediated downregulation of the GRα which, in turn, leads to a decrease in GC sensitivity, and effectively, the development of acquired GC resistance. Although the ligand-mediated downregulation of GRα is well documented, the precise factors which influence this process are not well understood and, thus, the development of an acquired GC resistance presents an ever-increasing challenge to the pharmaceutical industry. Recently, however, studies have correlated the dimerization status of the GRα with its ligand-mediated downregulation. Therefore, the current review will be discussing the major role-players in the homologous downregulation of the GRα pool, with a specific focus on previously reported GC-mediated reductions in GRα mRNA and protein levels, the molecular mechanisms through which the GRα functional pool is maintained and the possible impact of receptor conformation on GC-mediated GRα downregulation.

Sexual Dimorphism of Corticosteroid Signaling during Kidney Development

Sexual dimorphism involves differences between biological sexes that go beyond sexual characteristics. In mammals, differences between sexes have been demonstrated regarding various biological processes, including blood pressure and predisposition to develop hypertension early in adulthood, which may rely on early events during development and in the neonatal period. Recent studies suggest that corticosteroid signaling pathways (comprising glucocorticoid and mineralocorticoid signaling pathways) have distinct tissue-specific expression and regulation during this specific temporal window in a sex-dependent manner, most notably in the kidney. This review outlines the evidence for a gender differential expression and activation of renal corticosteroid signaling pathways in the mammalian fetus and neonate, from mouse to human, that may favor mineralocorticoid signaling in females and glucocorticoid signaling in males. Determining the effects of such differences may shed light on short term and long term pathophysiological consequences, markedly for males.