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Glucocorticoids are pleiotropic hormones, which are involved in almost every cellular, molecular and physiologic network of the organism, and regulate a broad spectrum of physiologic functions essential for life. The cellular response to glucocorticoids displays profound variability both in magnitude and in specificity of action. Tissue sensitivity to glucocorticoids differs among individuals, within tissues of the same individual and within the same cell. The actions of glucocorticoids are mediated by the glucocorticoid receptor, a ubiquitously expressed intracellular, ligand-dependent transcription factor. Multiple mechanisms, such as pre-receptor ligand metabolism, receptor isoform expression, and receptor-, tissue-, and cell type-specific factors, exist to generate diversity as well as specificity in the response to glucocorticoids. Alterations in the molecular mechanisms of glucocorticoid receptor action impair glucocorticoid signal transduction and alter tissue sensitivity to glucocorticoids. This review summarizes the recent advances in our understanding of the molecular mechanisms determining tissue sensitivity to glucocorticoids with particular emphasis on novel mutations and new information on the circadian rhythm and ligand-induced repression of the glucocorticoid receptor.
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... Individual glucocorticoid sensitivity and action predispose to substantial variation in adrenal suppression (42)(43)(44)(45) which are modulated by multiple factors including thyroid and growth hormone, comorbidities or medications that affect cortisol binding globulin, pre-receptor metabolism, hepatic metabolism, and glucocorticoid receptor isotypes, number and action (39,(42)(43)(44)(45). Some factors are influenced by genetic variation (46,47) and environmental factors might also influence glucocorticoid sensitivity (48). ...
... Individual glucocorticoid sensitivity and action predispose to substantial variation in adrenal suppression (42)(43)(44)(45) which are modulated by multiple factors including thyroid and growth hormone, comorbidities or medications that affect cortisol binding globulin, pre-receptor metabolism, hepatic metabolism, and glucocorticoid receptor isotypes, number and action (39,(42)(43)(44)(45). Some factors are influenced by genetic variation (46,47) and environmental factors might also influence glucocorticoid sensitivity (48). ...
Article
Glucocorticoid-induced adrenal insufficiency is caused by exogenous glucocorticoid suppression of the hypothalamic-pituitary-adrenal axis and is the most prevalent form of adrenal insufficiency. The condition is important to diagnose given the risk of life-threatening adrenal crisis and impact on patients' quality of life. The diagnosis is made with a stimulation test such as the ACTH-test. Until now, testing for glucocorticoid-induced adrenal insufficiency is often based on clinical suspicion rather than routinely, but accumulating evidence indicates that a significant number of cases will remain unrecognized. During ongoing oral glucocorticoid treatment or initially after withdrawal ~50% of patients have adrenal insufficiency, but outside clinical studies ≤1% of patients have adrenal testing recorded. More than 70% of cases are identified during acute hospital admission where the diagnosis can easily be missed as symptoms of adrenal insufficiency are non-specific and overlap those of the underlying and intercurrent conditions. Treatment of severe glucocorticoid-induced adrenal insufficiency should follow the principles for treatment of central adrenal insufficiency. The clinical implications and thus indication to treat mild-moderate adrenal deficiency after glucocorticoid withdrawal is not established. Also, the indication of adding stress dosages of glucocorticoid during ongoing glucocorticoid treatment remains unclear. In patients with established glucocorticoid-induced adrenal insufficiency, high rates of poor confidence in self-management and delayed glucocorticoid administration in the acute setting with an imminent adrenal crisis call for improved awareness and education of clinicians and patients. This article reviews different facets of glucocorticoid-induced adrenal insufficiency and discusses approaches to the condition in common clinical situations.
... The cellular response to GCs exhibits variability both in magnitude and in specificity of action, resulting in considerable heterogeneity in GC sensitivity. Multiple mechanisms, including pre-receptor ligand metabolism, receptor isoform expression, tissue-or cellspecific factors, and molecular heterogeneity of GR proteins are responsible for diversity and specificity in response to GCs [23]. Alterations in the molecular mechanisms of GR action may impair or enhance GC signal transduction and thus alter tissue sensitivity to GCs [65]. ...
... Several mutations and polymorphisms in the gene coding for the GR have been described and they have been associated with altered GC sensitivity and changes in body composition and metabolic parameters [23]. The most well-studied polymorphisms of NR3C1 gene are ER22/23EK, BclI, N363S, Tth111, GR-9β, and 22 C/A. ...
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Stress and depression increase the risk of Type 2 Diabetes (T2D) development. Evidence demonstrates that the Glucocorticoid (GC) negative feedback is impaired (GC resistance) in T2D patients resulting in Hypothalamic-Pituitary-Adrenal (HPA) axis hyperactivity and hypercortisolism. High GCs, in turn, activate multiple aspects of glucose homeostasis in peripheral tissues leading to hyperglycemia. Elucidation of the underlying molecular mechanisms revealed that Glucocorticoid Receptor (GR) mediates the GC-induced dysregulation of glucose production, uptake and insulin signaling in GC-sensitive peripheral tissues, such as liver, skeletal muscle, adipose tissue, and pancreas. In contrast to increased GR peripheral sensitivity, an impaired GR signaling in Peripheral Blood Mononuclear Cells (PBMCs) of T2D patients, associated with hyperglycemia, hyperlipidemia, and increased inflammation, has been shown. Given that GR changes in immune cells parallel those in brain, the above data implicate that a reduced brain GR function may be the biological link among stress, HPA hyperactivity, hypercortisolism and hyperglycemia. GR polymorphisms have also been associated with metabolic disturbances in T2D while dysregulation of micro-RNAs—known to target GR mRNA—has been described. Collectively, GR has a crucial role in T2D, acting in a cell-type and context-specific manner, leading to either GC sensitivity or GC resistance. Selective modulation of GR signaling in T2D therapy warrants further investigation.
... The remaining 537 olfactory receptor genes studied in HGCA2.0 were scattered throughout the coexpression tree. , also known as Glucocorticoid Receptor) is a nuclear receptor of the superfamily of ligand-dependent transcription factors, mediating the physiologic pleiotropic actions of glucocorticoids [106]. NR3C1 is ubiquitously expressed across almost all cell types, during all developmental stages. ...
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Genes with similar expression patterns in a set of diverse samples may be considered coexpressed. Human Gene Coexpression Analysis 2.0 (HGCA2.0) is a webtool which studies the global coexpression landscape of human genes. The website is based on the hierarchical clustering of 55,431 Homo sapiens genes based on a large-scale coexpression analysis of 3500 GTEx bulk RNA-Seq samples of healthy individuals, which were selected as the best representative samples of each tissue type. HGCA2.0 presents subclades of coexpressed genes to a gene of interest, and performs various built-in gene term enrichment analyses on the coexpressed genes, including gene ontologies, biological pathways, protein families, and diseases, while also being unique in revealing enriched transcription factors driving coexpression. HGCA2.0 has been successful in identifying not only genes with ubiquitous expression patterns, but also tissue-specific genes. Benchmarking showed that HGCA2.0 belongs to the top performing coexpression webtools, as shown by STRING analysis. HGCA2.0 creates working hypotheses for the discovery of gene partners or common biological processes that can be experimentally validated. It offers a simple and intuitive website design and user interface, as well as an API endpoint.
... Dex is known to suppress immune cell functions, in general [22], yet it is becoming clear that the response to GCs is highly cell-type-dependent. Responses differ both in terms of the individual genes and pathways affected, as well as in the magnitude of the transcriptional regulation and protein methylation of the GR [24,[43][44][45][46][47]. HTPCs have immunological roles and secrete cytokines [16][17][18]. ...
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The functions of human testicular peritubular cells (HTPCs), forming a small compartment located between the seminiferous epithelium and the interstitial areas of the testis, are not fully known but go beyond intratesticular sperm transport and include immunological roles. The expression of the glucocorticoid receptor (GR) indicates that they may be regulated by glucocorticoids (GCs). Herein, we studied the consequences of the GC dexamethasone (Dex) in cultured HTPCs, which serves as a unique window into the human testis. We examined changes in cytokines, mainly by qPCR and ELISA. A holistic mass-spectrometry-based proteome analysis of cellular and secreted proteins was also performed. Dex, used in a therapeutic concentration, decreased the transcript level of proinflammatory cytokines, e.g., IL6, IL8 and MCP1. An siRNA-mediated knockdown of GR reduced the actions on IL6. Changes in IL6 were confirmed by ELISA measurements. Of note, Dex also lowered GR levels. The proteomic results revealed strong responses after 24 h (31 significantly altered cellular proteins) and more pronounced ones after 72 h of Dex exposure (30 less abundant and 42 more abundant cellular proteins). Dex also altered the composition of the secretome (33 proteins decreased, 13 increased) after 72 h. Among the regulated proteins were extracellular matrix (ECM) and basement membrane components (e.g., FBLN2, COL1A2 and COL3A1), as well as PTX3 and StAR. These results pinpoint novel, profound effects of Dex in HTPCs. If transferrable to the human testis, changes specifically in ECM and the immunological state of the testis may occur in men upon treatment with Dex for medical reasons.
... The level of acetylated hGR was also correlated with the expressions of CLOCK-related genes in peripheral blood mononuclear cells (Nader et al., 2009). Taken together, these observations suggest that CLOCK is a negative regulator of action in target tissues (Nicolaides et al., 2014). ...
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Patients with Autism Spectrum Disorder (ASD) often exhibit disturbances in sleep, metabolism, and immune system. The molecular mechanisms for these clinical features in ASD are currently unknown. We demonstrated that circadian genes in the cells of patients with ASD often are dysregulated compared to controls. The dysregulation of circadian genes was reflected in two different ways: (1) abnormal levels of expression; and (2) a change of gene-gene association pattern in the co-expression network. We also observed a link between abnormal expression of circadian genes in lymphoblastoid cells with sleep phenotypes in patients with ASD. Our results suggest that circadian genes and circadian rhythms might play critical roles in the pathogenesis of ASD.
... As an output of the SCN, melatonin in turn functions as an input to all peripheral clocks, and since circulating melatonin varies with length of the dark phase, it reflects seasonal changes in daylength, and acts as a neuroendocrine mediator of the photoperiod (Cipolla-Neto et al., 2014). Circadian rhythms of circulating glucocorticoids are also a primary output of the SCN, in turn glucocorticoids regulate peripheral clocks through multiple mechanisms that include activation of its receptor and binding the glucocorticoid response elements (GRE) present in the promoter regions of PER1 and PER2 (So et al., 2009;Lamia et al., 2011;Cheon et al., 2013;Nicolaides et al., 2014). The SCN regulates the circadian release of glucocorticoids via nervous input to the hypothalamo-pituitary-adrenal axis which results in circadian oscillation of adrenocorticotropic hormone (ACTH) and sympathetic innervation of the adrenal gland, which directly controls glucocorticoid release (Lilley et al., 2012). ...
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The circadian system is an inbuilt timekeeping mechanism that tracks the 24-h day through the generation of circadian rhythms. Circadian rhythms enable animals to forecast and anticipate regular changes in their environment, and orchestrate biochemical, physiological and behavioral events so that the right process occurs at the right time. The 24 h rhythms generated by circadian clocks are integrated into homeostatic feedback loops and repair pathways. Metabolic and reproductive systems are highly integrated with the circadian timing system and demonstrate reciprocal regulation. Circadian clocks set the timing of circadian rhythms by gathering temporal information from external and internal signals to include light and nutrients. Exogenous and endogenous factors that function as inputs to the circadian clocks can disrupt their timing when applied at unusual and inappropriate times, and are referred to as chronodisruptors. Changes in the natural light-dark cycle perturb the circadian system. Other chronodisrupters include inappropriately timed food intake and physical activity and biological stress. Knowledge of the biology underlying circadian clock timing is critical to understanding how to maximize health and production efficiency of cattle. Here we review circadian clocks and their function in the regulation of metabolic and reproductive systems as well as the consequence of circadian disruption on mammary development and lactation with a particular focus on recent research findings from studies of dairy cows.
... Natural and synthetic glucocorticoid is one of the widely prescribed therapeutic compounds for treating and controlling inflammatory, lymphoproliferative, autoimmune, and neuromuscular diseases [8]. Synthetic glucocorticoids used in therapy include hydrocortisone, prednisone, and dexamethasone [9]. ...
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Glucocorticoid excess is a critical factor contributing to muscle atrophy. Both endogenous and exogenous glucocorticoids negatively affect the preservation of muscle mass and function. To date, the most effective intervention to prevent muscle atrophy is to apply a mechanical load in the form of resistance exercise. However, glucocorticoid-induced skeletal muscle atrophy easily causes fatigue in daily physical activities, such as climbing stairs and walking at a brisk pace, and reduces body movements to cause a decreased ability to perform physical activity. Therefore, providing adequate nutrients in these circumstances is a key factor in limiting muscle wasting and improving muscle mass recovery. The present review will provide an up-to-date review of the effects of various nutrients, including amino acids such as branched-chain amino acids (BCAAs) and β–hydroxy β–methylbutyrate (HMB), fatty acids such as omega-3, and vitamins and their derivates on the prevention and improvement of glucocorticoid-induced muscle atrophy.
... However, significant associations between genetic polymorphisms and severe adverse drug reactions have previously been identified from small cohorts and led to changes in clinical practice [30]. It has previously been shown that GR is involved in iatrogenic suppression of the HPA axis [31,32]. The most common causes of adrenal insufficiency are otherwise pituitary tumors, adrenal hemorrhage, infections, and autoimmune disease [33]. ...
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Background Single-nucleotide polymorphisms (SNPs) of the glucocorticoid receptor (GR) gene NR3C1 have been associated with an altered sensitivity to glucocorticoids, and thus may alter the therapeutic effects of glucocorticoids. We investigated the prevalence of adrenal suppression after treatment with glucocorticoids and evaluated whether GR SNPs were associated with altered risks of adrenal suppression and metabolic disorders in patients with chronic obstructive pulmonary disease (COPD). Methods In an observational prospective cohort study, we recruited 78 patients with severe COPD receiving 5 days glucocorticoid treatment for an exacerbation of COPD. In total, 55% of these patients were also receiving regular inhaled corticosteroids (ICS). Adrenal function was evaluated with a corticotropin test 30 days after the exacerbation. Patients were genotyped for Bcl1 , N363S , ER22/23EK , and 9β SNPs. Results The prevalence of adrenal suppression (corticotropin-stimulated plasma-cortisol ≤ 420 nmol/L) 30 days after glucocorticoid treatment was 4/78 (5%). There was no difference between carriers and non-carriers of the polymorphisms ( Bcl1 , 9β , ER22/23K , and N363S ) in corticotropin stimulated plasma-cortisol concentrations. In the haplotype analyses, we included the 50 patients who had a high-sensitivity (76%), a low-sensitivity (4%), or a wild-type (20%) GR haplotype. There was no difference in the frequency of adrenal suppression or metabolic disorders between the two stratified groups: (a) high-sensitivity ( Bcl1 and/or N363S ) haplotypes vs. (b) low-sensitivity ( 9β and/or ER22/23K ) plus wild-type haplotypes ( p > 0.05). Carriers of the high-sensitivity GR gene haplotype exhibited a steeper decline in stimulated P-cortisol with increased ICS dose (slope, –1.35 vs. 0.94; p = 0.17), compared to the group with low-sensitivity or wild-type haplotypes, respectively. Conclusions In total, 5% of patients exhibited insufficient adrenal function. The Bcl1 and N363S polymorphisms did not seem to increase the risk of glucocorticoid suppression or metabolic disorders in adults treated with glucocorticoids for COPD exacerbations.
... Increased expression of peripheral blood cell cGRα and cGR-P might be an adaptive mechanism for increased demand of the anti-inflammatory effect of cortisol. On the other hand, SIRS patients with markedly elevated serum cortisol level might have lower cGRα and cGRP expression due to the ligand-induced receptor downregulation 7 . Several human studies suggest that elevated serum cortisol level and/ or decreased expression of GR in peripheral leukocytes correspond to a more severe disease course and poor outcome in patients with septic or non-septic SIRS [46][47][48] . ...
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Glucocorticoids play a central role in the inflammatory response and alleviate the symptoms in critically ill patients. The glucocorticoid action relies on the glucocorticoid receptor (GR) which translocates into the nucleus upon ligand-binding and regulates transcription of a battery of genes. Although the GR is encoded by a single gene, dozens of its splice variants have been described in diverse species. The GRα isoform encodes the full, functionally active protein that is composed of a transactivation, a DNA-binding, and a C-terminal ligand-binding domain. The second most highly expressed receptor variant, the GR-P, is formed by an intron retention that introduces an early stop codon and results in a probably dysfunctional protein with truncated ligand-binding domain. We described the canine ortholog of GR-P and showed that this splice variant is highly abundant in the peripheral blood of dogs. The level of cGRα and cGR-P transcripts are elevated in patients of SIRS and the survival rate is increased with elevated cGRα and cGR-P expression. The ratio of cGRα and cGR-P mRNA did not differ between the survivor and non-survivor patients; thus, the total GR expression is more pertinent than the relative expression of GR isoforms in assessment of the disease outcome.
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Introduction: Corticosteroids are an important pillar in many anti-inflammatory and immunosuppressive treatment regimens and are available in natural and synthetic forms, which are considered equipotent if clinical bioequivalence data are used. Current clinical bioequivalence data are however based on animal studies or studies with subjective endpoints. Furthermore, advancement in steroid physiology with regard to metabolism, intracellular handling and receptor activation have not yet been incorporated. Therefore, this study aims to re-examine the clinical bioequivalence and dose effects of the most widely used synthetic corticosteroids, prednisolone and dexamethasone. Methods and analysis: In this double-blind, randomised cross-over clinical trial, 24 healthy male and female volunteers aged 18-75 years, will be included. All volunteers will randomly receive either first a daily dose of 7.5 mg prednisolone for 1 week, immediately followed by a daily dose of 30 mg prednisolone for 1 week, or first a presumed clinical bioequivalent dose of 1.125 mg dexamethasone per day, immediately followed by 4.5 mg of dexamethasone per day for 1 week. After a wash-out period of 4-8 weeks, the other treatment will be applied. The primary study endpoint is the difference in free cortisol excretion in 24 hours urine. Secondary endpoints will include differences in immunological parameters, blood pressure and metabolic measurements. Ethics and dissemination: This study has been approved by the Medical Ethics Committee of the University Medical Center Groningen (METC 2020.398). The results of this study will be submitted for publication in peer-reviewed journals. Trial registration number: ClinicalTrials.gov (Identifier: NCT04733144), and in the Dutch trial registry (NL9138).
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Context: Primary generalized glucocorticoid resistance is a rare genetic disorder characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. The molecular basis of the condition has been ascribed to inactivating mutations in the human glucocorticoid receptor (hGR) gene. Objective: The objective of the study was to present three new cases caused by a novel mutation in the hGR gene and to delineate the molecular mechanisms through which the mutant receptor impairs glucocorticoid signal transduction. Design and results: The index case (father) and his two daughters presented with increased urinary free cortisol excretion and resistance of the hypothalamic-pituitary-adrenal axis to dexamethasone suppression in the absence of clinical manifestations suggestive of Cushing syndrome. All subjects harbored a novel, heterozygous, point mutation (T→G) at nucleotide position 1724 of the hGR gene, which resulted in substitution of valine by glycine at amino acid 575 of the receptor. Compared with the wild-type receptor, the hGRαV575G demonstrated a significant (33%) reduction in its ability to transactivate the mouse mammary tumor virus promoter in response to dexamethasone, a 50% decrease in its affinity for the ligand, and a 2.5-fold delay in nuclear translocation. Although it did not exert a dominant negative effect on the wild-type receptor and preserved its ability to bind to DNA, hGRαV575G displayed significantly enhanced (∼80%) ability to transrepress the nuclear factor-κΒ signaling pathway. Finally, the mutant receptor hGRαV575G demonstrated impaired interaction with the LXXLL motif of the glucocorticoid receptor-interacting protein 1 coactivator in vitro and in computer-based structural simulation via its defective activation function-2 (AF-2) domain. Conclusions: The natural mutant receptor hGRαV575G causes primary generalized glucocorticoid resistance by affecting multiple steps in the glucocorticoid signaling cascade, including the affinity for the ligand, the time required for nuclear translocation, and the interaction with the glucocorticoid-interacting protein-1 coactivator.
Article
The stress system effectively restores the internal balance-or homeostasis-of living organisms in the face of random external or internal changes, the stressors. This highly complex system helps organisms to provide a series of neuroendocrine responses to stressors-the stress response-through coordinated activation of the hypothalamic-pituitary-adrenal (HPA) axis and the locus coeruleus/norepinephrine autonomic nervous systems. In addition to stressors, life is influenced by daily light/dark changes due to the 24-h rotation of Earth. To adjust to these recurrent day/night cycles, the biological clock system employs the heterodimer of transcription factors circadian locomotor output cycle kaput/brain-muscle-arnt-like protein 1 (CLOCK/BMAL1), along with a set of other transcription factors, to regulate the circadian pattern of gene expression. Interestingly, the stress system, through the HPA axis, communicates with the clock system; therefore, any uncoupling or dysregulation could potentially cause several disorders, such as metabolic, autoimmune, and mood disorders. In this review, we discuss the biological function of the two systems, their interactions, and the clinical implications of their dysregulation or uncoupling.
Article
Glucocorticoid (GC) plays important roles in diverse physiological processes including metabolism and immune functions. While circadian control of GC synthesis and secretion is relatively well appreciated, circadian control of GC action within target tissues remains poorly understood. Here, we demonstrate that CLOCK/BMAL1, the core circadian clock components, reduces maximal GR transactivation (Amax) as well as efficacy (EC50) by a novel mechanism that requires binding to DNA and transactivation of target genes. Accordingly, we observe that PER1 and CRY1, the primary targets of CLOCK/BMAL1 action, reduce maximal GR transactivation while not affecting the efficacy. Moreover, we observe hyper-activations of GRE-dependent transcription in BMAL1- or PERs-deficient MEFs. In addition, endogenous GC target genes expression negatively correlates with the CLOCK/BMAL1 activity. Considering that GC sensitivity is widely implicated in human health and diseases, these results provide valuable insights into plethora of GC-related physiology and pathology.