Estrogen inhibits glucocorticoid action via protein phosphatase 5 (PP5)-mediated glucocorticoid receptor dephosphorylation

Glucocorticoids, their uses, sexual dimorphisms, and diseases: new concepts, mechanisms, and discoveries

The normal stress response in humans is governed by the hypothalamic-pituitary-adrenal (HPA) axis through heightened mechanisms during stress, raising blood levels of the glucocorticoid hormone cortisol. Glucocorticoids are quintessential compounds that balance the proper functioning of numerous systems in the mammalian body. They are also generated synthetically and are the preeminent therapy for inflammatory diseases. They act by binding to the nuclear receptor transcription factor glucocorticoid receptor (GR), which has two main isoforms (GRα and GRβ). Our classical understanding of glucocorticoid signaling is from the GRα isoform, which binds the hormone, whereas GRβ has no known ligands. With glucocorticoids being involved in many physiological and cellular processes, even small disruptions in their release via the HPA axis, or changes in GR isoform expression, can have dire ramifications on health. Long-term chronic glucocorticoid therapy can lead to a glucocorticoid-resistant state, and we deliberate how this impacts disease treatment. Chronic glucocorticoid treatment can lead to noticeable side effects such as weight gain, adiposity, diabetes, and others that we discuss in detail. There are sexually dimorphic responses to glucocorticoids, and women tend to have a more hyperresponsive HPA axis than men. This review summarizes our understanding of glucocorticoids and critically analyzes the GR isoforms and their beneficial and deleterious mechanisms and the sexual differences that cause a dichotomy in responses. We also discuss the future of glucocorticoid therapy and propose a new concept of dual GR isoform agonist and postulate why activating both isoforms may prevent glucocorticoid resistance.

Novel neurosteroid therapeutics for post-partum depression: perspectives on clinical trials, program development, active research, and future directions

This article reviews novel neurosteroid therapeutics for post-partum depression, with a focus on their development, clinical trial data, current practices, and future directions in this exciting field. We discuss the clinical impact of brexanolone and several other neurosteroids, particularly as they relate to the treatment of postpartum depression (PPD) and major depressive disorders outside of the perinatal period. There has been increasing interest in GABA signaling and modulation as it pertains to the development of altered circuity and depressive states. This scientific underpinning served as the rationale for the initial development of brexanolone. We review the clinical trials supporting its Food and Drug Administration (FDA) approval as the first rapidly acting antidepressant specific for PPD, and the subsequent development of a clinical brexanolone program at an academic medical center, highlighting new research and data from that site as well as the challenges with the delivery of this I.V. drug. In addition to the GABA signaling hypothesis, we discuss the new evidence demonstrating that brexanolone inhibits inflammatory signaling post-infusion, suggesting that inflammatory signaling may contribute to the etiology of PPD. Finally, we describe new and future directions in neurosteroid therapeutics, including the development of an oral agent, zuranolone, and the IV and oral formulations of ganaxolone. Ultimately, the hope is that these novel neurosteroid therapeutics will provide fast-acting treatment for these impairing disorders and improve our understanding of the underlying mechanisms of depressive disorders.

Systems Genomics Reveals microRNA Regulation of ICS Response in Childhood Asthma

BACKGROUND

Asthmatic patients' responses to inhaled corticosteroids (ICS) are variable and difficult to quantify. We have previously defined a Cross-sectional Asthma STEroid Response (CASTER) measure of ICS response. MicroRNAs (miRNAs) have shown strong effects on asthma and inflammatory processes.

OBJECTIVE

The purpose of this study was to identify key associations between circulating miRNAs and ICS response in childhood asthma.

METHODS

Small RNA sequencing in peripheral blood serum from 580 children with asthma on ICS treatment from The Genetics of Asthma in Costa Rica Study (GACRS) was used to identify miRNAs associated with ICS response using generalized linear models. Replication was conducted in children on ICS from the Childhood Asthma Management Program (CAMP) cohort. The association between replicated miRNAs and the transcriptome of lymphoblastoid cell lines in response to a glucocorticoid was assessed.

RESULTS

The association study on the GACRS cohort identified 36 miRNAs associated with ICS response at 10% false discovery rate (FDR), three of which (miR-28-5p, miR-339-3p, and miR-432-5p) were in the same direction of effect and significant in the CAMP replication cohort. In addition, in vitro steroid response lymphoblastoid gene expression analysis revealed 22 dexamethasone responsive genes were significantly associated with three replicated miRNAs. Furthermore, Weighted Gene Co-expression Network Analysis (WGCNA) revealed a significant association between miR-339-3p and two modules (black and magenta) of genes associated with immune response and inflammation pathways.

CONCLUSION

This study highlighted significant association between circulating miRNAs miR-28-5p, miR-339-3p, and miR-432-5p and ICS response. miR-339-3p may be involved in immune dysregulation, which leads to a poor response to ICS treatment.

Melatonin-mediated FKBP4 downregulation protects against stress-induced neuronal mitochondria dysfunctions by blocking nuclear translocation of GR

The physiological crosstalk between glucocorticoid and melatonin maintains neuronal homeostasis in regulating circadian rhythms. However, the stress-inducing level of glucocorticoid triggers mitochondrial dysfunction including defective mitophagy by increasing the activity of glucocorticoid receptors (GRs), leading to neuronal cell death. Melatonin then suppresses glucocorticoid-induced stress-responsive neurodegeneration; however, the regulatory mechanism of melatonin, i.e., associated proteins involved in GR activity, has not been elucidated. Therefore, we investigated how melatonin regulates chaperone proteins related to GR trafficking into the nucleus to suppress glucocorticoid action. In this study, the effects of glucocorticoid on suppressing NIX-mediated mitophagy, followed by mitochondrial dysfunction, neuronal cell apoptosis, and cognitive deficits were reversed by melatonin treatment by inhibiting the nuclear translocation of GRs in both SH-SY5Y cells and mouse hippocampal tissue. Moreover, melatonin selectively suppressed the expression of FKBP prolyl isomerase 4 (FKBP4), which is a co-chaperone protein that works with dynein, to reduce the nuclear translocation of GRs among the chaperone proteins and nuclear trafficking proteins. In both cells and hippocampal tissue, melatonin upregulated melatonin receptor 1 (MT1) bound to Gαq, which triggered the phosphorylation of ERK1. The activated ERK then enhanced DNA methyltransferase 1 (DNMT1)-mediated hypermethylation of FKBP52 promoter, reducing GR-mediated mitochondrial dysfunction and cell apoptosis, the effects of which were reversed by knocking down DNMT1. Taken together, melatonin has a protective effect against glucocorticoid-induced defective mitophagy and neurodegeneration by enhancing DNMT1-mediated FKBP4 downregulation that reduced the nuclear translocation of GRs.

Sex Differences in Depression Caused by Early Life Stress and Related Mechanisms

Depression is a common psychiatric disease caused by various factors, manifesting with continuous low spirits, with its precise mechanism being unclear. Early life stress (ELS) is receiving more attention as a possible cause of depression. Many studies focused on the mechanisms underlying how ELS leads to changes in sex hormones, neurotransmitters, hypothalamic pituitary adrenocortical (HPA) axis function, and epigenetics. The adverse effects of ELS on adulthood are mainly dependent on the time window when stress occurs, sex and the developmental stage when evaluating the impacts. Therefore, with regard to the exact sex differences of adult depression, we found that ELS could lead to sex-differentiated depression through multiple mechanisms, including 5-HT, sex hormone, HPA axis, and epigenetics.

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.

ACTN3 genotype influences skeletal muscle mass regulation and response to dexamethasone

Homozygosity for the common ACTN3 null polymorphism (ACTN3 577X) results in α-actinin-3 deficiency in ~20% of humans worldwide and is linked to reduced sprint and power performance in both elite athletes and the general population. α-Actinin-3 deficiency is also associated with reduced muscle mass, increased risk of sarcopenia, and altered muscle wasting response induced by denervation and immobilization. Here, we show that α-actinin-3 plays a key role in the regulation of protein synthesis and breakdown signaling in skeletal muscle and influences muscle mass from early postnatal development. We also show that α-actinin-3 deficiency reduces the atrophic and anti-inflammatory response to the glucocorticoid dexamethasone in muscle and protects against dexamethasone-induced muscle wasting in female but not male mice. The effects of α-actinin-3 deficiency on muscle mass regulation and response to muscle wasting provide an additional mechanistic explanation for the positive selection of the ACTN3 577X allele in recent human history.

Glucocorticoid Receptor: A Multifaceted Actor in Breast Cancer

Breast cancer (BC) is one of the most common cancers in women worldwide. Even though the role of estrogen receptor alpha (ERα) is extensively documented in the development of breast tumors, other members of the nuclear receptor family have emerged as important players. Synthetic glucocorticoids (GCs) such as dexamethasone (dex) are commonly used in BC for their antiemetic, anti-inflammatory, as well as energy and appetite stimulating properties, and to manage the side effects of chemotherapy. However, dex triggers different effects depending on the BC subtype. The glucocorticoid receptor (GR) is also an important marker in BC, as high GR expression is correlated with a poor and good prognosis in ERα-negative and ERα-positive BCs, respectively. Indeed, though it drives the expression of pro-tumorigenic genes in ERα-negative BCs and is involved in resistance to chemotherapy and metastasis formation, dex inhibits estrogen-mediated cell proliferation in ERα-positive BCs. Recently, a new natural ligand for GR called OCDO was identified. OCDO is a cholesterol metabolite with oncogenic properties, triggering mammary cell proliferation in vitro and in vivo. In this review, we summarize recent data on GR signaling and its involvement in tumoral breast tissue, via its different ligands.

Controlled Release of Anti-Inflammatory and Proangiogenic Factors from Macroporous Scaffolds

The simultaneous local delivery of anti-inflammatory and proangiogenic agents via biomaterial scaffolds presents a promising method for improving the engraftment of tissue-engineered implants while avoiding potentially detrimental systemic delivery. In this study, polydimethylsiloxane (PDMS) microbeads were loaded with either anti-inflammatory dexamethasone (Dex) or proangiogenic 17β-estradiol (E2) and subsequently integrated into a single macroporous scaffold to create a controlled, dual-drug delivery platform. Compared to a standard monolithic drug dispersion scaffold, macroporous scaffolds containing drug-loaded microbeads exhibited reduced initial burst release and increased durability of drug release for both agents. The incubation of scaffolds with lipopolysaccharide (LPS)-stimulated M1 macrophages found that Dex suppressed the production of proinflammatory and proangiogenic factors when compared to drug-free control scaffolds; however, the coincubation of macrophages with Dex and E2 scaffolds restored their proangiogenic features. Following implantation, Dex-loaded microbead scaffolds (Dex-μBS) suppressed host cell infiltration and integration, when compared to controls. In contrast, the codelivery of dexamethasone with estrogen from the microbead scaffold (Dex+E2-μBS) dampened overall host cell infiltration, but restored graft vascularization. These results demonstrate the utility of a microbead scaffold approach for the controlled, tailored, and local release of multiple drugs from an open framework implant. It further highlights the complementary impacts of local Dex and E2 delivery to direct the healthy integration of implants, which has broad applications to the field of tissue engineering and regenerative medicine.

Tributyltin enhanced anxiety of adult male zebrafish through elevating cortisol level and disruption in serotonin, dopamine and gamma-aminobutyric acid neurotransmitter pathways

Tributyltin (TBT), a widely and persistently distributed organontin, has been well documented to disrupt reproduction and behaviors in animals due to its anti-aromatase activity. TBT has been also reported to enhance anxiety in several fish species, whereas the mechanism underlying remains largely unknown. To investigate the disruption of TBT on fish anxiety and the mechanisms possibly involved, adult male zebrafish (Danio rerio) were treated with TBT (100 and 500 ng/L) for 28 days and anxiety behavior was further investigated using a novel tank dive test. Result showed that TBT treatment significantly enhanced the total time of the fish spent in the lower half, delayed the onset time to the higher half of the tank and increased the total duration of freezing of the fish, indicating an enhanced anxiety in TBT-treated fish. Accordingly, TBT sharply elevated the cortisol levels in plasma in a concentration-dependent manner, suggesting that the elevated cortisol level might be involved in the enhanced anxiety. Although the expression of crha was significantly increased and crhbp was significantly decreased in the brain of TBT-treated fish which is consistent to the elevated cortisol level, the expressions of actha and acthb were sharply down-regulated. In contrast, the expressions of genes responsible for the synthesis and action of serotonin (5-HT) (pet1, thp2 and htr1aa), dopamine (DA) (th1, slc6a3, drd2a and drd2b) and gamma-aminobutyric acid (GABA) (gad2 and gabrg2) were all significantly inhibited. The down-regulation of these pivotal genes acting in 5-HT, DA and GABA neurotransmitter systems in response to TBT corresponded well with the TBT-enhanced anxiety in fish. It was thus strongly suggested that these neurotransmitters might be also involved in TBT-enhanced anxiety in adult male zebrafish. The present study extended our understanding of the neurotoxicity of TBT on the anxiety control and behavioral modulation in fish.

Stress, Sex, and Sugar: Glucocorticoids and Sex-Steroid Crosstalk in the Sex-Specific Misprogramming of Metabolism

Early-life exposures to environmental insults can misprogram development and increase metabolic disease risk in a sex-dependent manner by mechanisms that remain poorly characterized. Modifiable factors of increasing public health relevance, such as diet, psychological stress, and endocrine-disrupting chemicals, can affect glucocorticoid receptor signaling during gestation and lead to sex-specific postnatal metabolic derangements. Evidence from humans and animal studies indicate that glucocorticoids crosstalk with sex steroids by several mechanisms in multiple tissues and can affect sex-steroid-dependent developmental processes. Nonetheless, glucocorticoid sex-steroid crosstalk has not been considered in the glucocorticoid-induced misprogramming of metabolism. Herein we review what is known about the mechanisms by which glucocorticoids crosstalk with estrogen, androgen, and progestogen action. We propose that glucocorticoid sex-steroid crosstalk is an understudied mechanism of action that requires consideration when examining the developmental misprogramming of metabolism, especially when assessing sex-specific outcomes.

Glucocorticoid receptor modulation decreases ER-positive breast cancer cell proliferation and suppresses wild-type and mutant ER chromatin association

Background

Non-ER nuclear receptor activity can alter estrogen receptor (ER) chromatin association and resultant ER-mediated transcription. Consistent with GR modulation of ER activity, high tumor glucocorticoid receptor (GR) expression correlates with improved relapse-free survival in ER+ breast cancer (BC) patients.

Methods

In vitro cell proliferation assays were used to assess ER-mediated BC cell proliferation following GR modulation. ER chromatin association following ER/GR co-liganding was measured using global ChIP sequencing and directed ChIP analysis of proliferative gene enhancers.

Results

We found that GR liganding with either a pure agonist or a selective GR modulator (SGRM) slowed estradiol (E2)-mediated proliferation in ER+ BC models. SGRMs that antagonized transcription of GR-unique genes both promoted GR chromatin association and inhibited ER chromatin localization at common DNA enhancer sites. Gene expression analysis revealed that ER and GR co-activation decreased proliferative gene activation (compared to ER activation alone), specifically reducing CCND1, CDK2, and CDK6 gene expression. We also found that ligand-dependent GR occupancy of common ER-bound enhancer regions suppressed both wild-type and mutant ER chromatin association and decreased corresponding gene expression. In vivo, treatment with structurally diverse SGRMs also reduced MCF-7 Y537S ER-expressing BC xenograft growth.

Conclusion

These studies demonstrate that liganded GR can suppress ER chromatin occupancy at shared ER-regulated enhancers, including CCND1 (Cyclin D1), regardless of whether the ligand is a classic GR agonist or antagonist. Resulting GR-mediated suppression of ER+ BC proliferative gene expression and cell division suggests that SGRMs could decrease ER-driven gene expression.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1164-6) contains supplementary material, which is available to authorized users.

Hormone Therapy and Breast Cancer: Emerging Steroid Receptor Mechanisms

Although hormone therapy is widely used by millions of women to relieve symptoms of menopause, it has been associated with several side-effects such as coronary heart disease, stroke and increased invasive breast cancer risk. These side-effects have caused many women to seek alternatives to conventional hormone therapy, including the controversial custom-compounded bioidentical hormone therapy suggested to not increase breast cancer risk. Historically estrogens and the estrogen receptor were considered the principal factors promoting breast cancer development and progression, however, a role for other members of the steroid receptor family in breast cancer pathogenesis is now evident, with emerging studies revealing an interplay between some steroid receptors. In this review, we discuss examples of hormone therapy used for the relief of menopausal symptoms, highlighting the distinction between conventional hormone therapy and custom-compounded bioidentical hormone therapy. Moreover, we highlight the fact that not all hormones have been evaluated for an association with increased breast cancer risk. We also summarize the current knowledge regarding the role of steroid receptors in mediating the carcinogenic effects of hormones used in menopausal hormone therapy, with special emphasis on the influence of the interplay or crosstalk between steroid receptors. Unraveling the intertwined nature of steroid hormone receptor signaling pathways in breast cancer biology is of utmost importance, considering that breast cancer is the most prevalent cancer among women worldwide. Moreover, understanding these mechanisms may reveal novel prevention or treatment options, and lead to the development of new hormone therapies that does not cause increased breast cancer risk.

Glucocorticoid Receptor and Adipocyte Biology

Glucocorticoids are steroid hormones that play a key role in metabolic adaptations during stress, such as fasting and starvation, in order to maintain plasma glucose levels. Excess and chronic glucocorticoid exposure, however, causes metabolic syndrome including insulin resistance, dyslipidemia, and hyperglycemia. Studies in animal models of metabolic disorders frequently demonstrate that suppressing glucocorticoid signaling improves insulin sensitivity and metabolic profiles. Glucocorticoids convey their signals through an intracellular glucocorticoid receptor (GR), which is a transcriptional regulator. The adipocyte is one cell type that contributes to whole body metabolic homeostasis under the influence of GR. Glucocorticoids' functions on adipose tissues are complex. Depending on various physiological or pathophysiological states as well as distinct fat depots, glucocorticoids can either increase or decrease lipid storage in adipose tissues. In rodents, glucocorticoids have been shown to reduce the thermogenic activity of brown adipocytes. However, in human acute glucocorticoid exposure, glucocorticoids act to promote thermogenesis. In this article, we will review the recent studies on the mechanisms underlying the complex metabolic functions of GR in adipocytes. These include studies of the metabolic outcomes of adipocyte specific GR knockout mice and identification of novel GR primary target genes that mediate glucocorticoid action in adipocytes.

Protein phosphatase 5 and the tumor suppressor p53 down-regulate each other's activities in mice

Protein phosphatase 5 (PP5), a serine/threonine phosphatase, has a wide range of biological functions and exhibits elevated expression in tumor cells. We previously reported that pp5-deficient mice have altered ataxia-telangiectasia mutated (ATM)-mediated signaling and function. However, this regulation was likely indirect, as ATM is not a known PP5 substrate. In the current study, we found that pp5-deficient mice are hypersensitive to genotoxic stress. This hypersensitivity was associated with the marked up-regulation of the tumor suppressor tumor protein p53 and its downstream targets cyclin-dependent kinase inhibitor 1A (p21), MDM2 proto-oncogene (MDM2), and phosphatase and tensin homolog (PTEN) in pp5-deficient tissues and cells. These observations suggested that PP5 plays a role in regulating p53 stability and function. Experiments conducted with p53 ^+/- pp5 ^+/- or p53 ^+/- pp5 ^-/- mice revealed that complete loss of PP5 reduces tumorigenesis in the p53 ^+/- mice. Biochemical analyses further revealed that PP5 directly interacts with and dephosphorylates p53 at multiple serine/threonine residues, resulting in inhibition of p53-mediated transcriptional activity. Interestingly, PP5 expression was significantly up-regulated in p53-deficient cells, and further analysis of pp5 promoter activity revealed that p53 strongly represses PP5 transcription. Our results suggest a reciprocal regulatory interplay between PP5 and p53, providing an important feedback mechanism for the cellular response to genotoxic stress.

Possible roles for glucocorticoid signalling in breast cancer

Our understanding of breast cancer biology, and our ability to manipulate breast cancers have grown exponentially in the last 20 years. Much of that expansion has focused on the roles of steroids in driving these neoplasms. Initially this research focused on estrogens and progesterone receptors, and more recently on androgen actions in breast cancers. This review aims to make the case for glucocorticoids as the next essential steroid subclass that contributes significantly to our understanding of steroidogenic regulation of these neoplasms. Glucocorticoids have the potential to play multiple roles in the regulation of breast cancers including their control of cellular differentiation, apoptosis and proliferation. Beyond this they also act as a master integrator of organ homeostats in relation to such as circadian rhythms and stress responses. Therefore a better understanding of glucocorticoids and breast cancer could help to explain some of the epidemiological links between circadian disruption and/or stress and breast cancer development. Finally glucocorticoids are currently used during chemotherapeutic treatment in breast cancer therapy and yet results of various studies suggest that this may have an adverse impact on treatment success. This review aims to summarise the current evidence for glucocorticoids as actors in breast cancer and then suggest future essential approaches in order to determine the roles of glucocorticoids in this disease.

Regulation of the Hsp90 system

Hsp90 is a highly conserved and abundant chaperone. It participates in essential cellular activities by supporting the maturation process of its client proteins, many of which are protein kinases and steroid receptors. Client processing is achieved via extensive conformational changes within the dimeric chaperone. This requires an ATP hydrolysis activity that is controlled by auto-inhibitory mechanisms and several structurally diverse cofactors. Especially the client-specificity of Hsp90 depends on client-specific cofactors, which can adapt Hsp90's activities to the client requirements at different conditions and in different cell types. Additionally, post-translational modifications can influence almost every aspect of Hsp90's interactions and activities. In this review, we present these regulatory principles, discuss the factors that have an impact on Hsp90's function and elaborate the mechanisms that are responsible for regulating the Hsp90 machinery.

The effects of ovarian hormones on stressor-induced hormonal responses, glucocorticoid receptor expression and translocation, and genes related to receptor signaling in adult female rats

Estradiol potentiates hypothalamic-pituitary-adrenal activity and delays the return of glucocorticoid secretion to baseline after a stressor exposure in female rats; we investigated whether estradiol effects involve actions on glucocorticoid receptor (GR) translocation and expression of receptor co-chaperones. In Experiment 1 intact females and ovariectomized (OVX) females were treated for four days with vehicle (VEH), 17β-estradiol benzoate (EB), or EB and progesterone (EB + P). Samples were taken from rats in the home cage (baseline) or after 30 min of restraint stress in a plastic restrainer (post-restraint) (n = 10/group). OVX-VEH treatment reduced baseline and post-restraint plasma concentrations of corticosterone versus all other treatments. Western blots indicated that OVX-VEH treated rats had greater hippocampal cytosolic GR expression than other treatments. Stress increased hippocampal nuclear GR expression, but without treatment differences. In Experiment 2 OVX rats were treated daily with VEH, EB, or EB + P (n = 8/group). OVX-VEH rats showed a lower stimulation of corticosterone secretion by restraint stress than other treatments and OVX-EB + P treated rats had lower concentrations than the OVX-EB group, suggesting progesterone mitigated estradiol effects. Quantitative polymerase chain reaction experiments indicated that stress increased Fkbp5 mRNA in the ventral hippocampus, with no effect of stress or treatment on Nr3c1 (GR), Nr3c2 (MR), Fkbp4, Bag1, or Ncoa1 (SRC-1) expression. Thus, the hypothesis is that estradiol effects on negative feedback are mediated by altered expression of receptor co-chaperones or co-modulators in the hippocampus was not supported. Estradiol may blunt feedback by limiting the availability of cytosolic GR protein.

Serine/threonine phosphatase 5 (PP5C/PPP5C) regulates the ISOC channel through a PP5C-FKBP51 axis

Pulmonary endothelial cells express a store-operated calcium entry current (I_soc), which contributes to inter-endothelial cell gap formation. I_soc is regulated by a heterocomplex of proteins that includes the immunophilin FKBP51. FKBP51 inhibits I_soc by mechanisms that are not fully understood. In pulmonary artery endothelial cells (PAECs) we have shown that FKBP51 increases microtubule polymerization, an event that is critical for I_soc inhibition by FKBP51. In neurons, FKBP51 promotes microtubule stability through facilitation of tau dephosphorylation. However, FKBP51 does not possess phosphatase activity. Protein phosphatase 5 (PP5C/PPP5C) can dephosphorylate tau, and similar to FKBP51, PP5C possesses tetratricopeptide repeats (TPR) that mediate interaction with heat shock protein-90 (HSP90) chaperone/scaffolding complexes. We therefore tested whether PP5C contributes to FKBP51-mediated inhibition of I_soc. Both siRNA-mediated suppression of PP5C expression in PAECs and genetic disruption of PP5C in HEK293 cells attenuate FKBP51-mediated inhibition of I_soc. Reintroduction of catalytically competent, but not catalytically inactive PP5C, restored FKBP51-mediated inhibition of I_soc. PAEC cell fractionation studies identified both PP5C and the ISOC heterocomplex in the same membrane fractions. Further, PP5C co-precipitates with TRPC4, an essential subunit of ISOC channel. Finally, to determine if PP5C is required for FKBP51-mediated inhibition of calcium entry-induced inter-endothelial cell gap formation, we measured gap area by wide-field microscopy and performed biotin gap quantification assay and electric cell-substrate impedance sensing (ECIS®). Collectively, the data presented indicate that suppression of PP5C expression negates the protective effect of FKBP51. These observations identify PP5C as a novel member of the ISOC heterocomplex that is required for FKBP51-mediated inhibition of I_soc.

The Immunoexpression of Glucocorticoid Receptors in Breast Carcinomas, Lactational Change, and Normal Breast Epithelium and Its Possible Role in Mammary Carcinogenesis

The role of estrogen and progesterone receptors in breast cancer biology is well established. In contrast, other steroid hormones are less well studied. Glucocorticoids (GCs) are known to play a role in mammary development and differentiation; thus, it is of interest to attempt to delineate their immunoexpression across a spectrum of mammary epithelia. Aim. To delineate the distribution pattern of glucocorticoid receptors (GRs) in malignant versus nonmalignant epithelium with particular emphasis on lactational epithelium. Materials and Methods. Immunohistochemistry (IHC) for GRs was performed on archival formalin-fixed paraffin-embedded tissue blocks of 96 cases comprising 52 invasive carcinomas, 21 cases with lactational change, and 23 cases showing normal mammary tissue histology. Results. Results reveal an overexpression of GRs in mammary malignant epithelium as compared to both normal and lactational groups individually and combined. GR overexpression is significantly more pronounced in HER-2-negative cancers. Discussion. This is the first study to compare GR expression in human lactating epithelium versus malignant and normal epithelium. The article discusses the literature related to the pathobiology of GCs in the breast with special emphasis on breast cancer. Conclusion. The lactational epithelium did not show overexpression of GR, while GR was overexpressed in mammary NST (ductal) carcinoma, particularly HER-2-negative cancers.

Genomic and epigenomic mechanisms of glucocorticoids in the brain

Following the discovery of glucocorticoid receptors in the hippocampus and other brain regions, research has focused on understanding the effects of glucocorticoids in the brain and their role in regulating emotion and cognition. Glucocorticoids are essential for adaptation to stressors (allostasis) and in maladaptation resulting from allostatic load and overload. Allostatic overload, which can occur during chronic stress, can reshape the hypothalamic-pituitary-adrenal axis through epigenetic modification of genes in the hippocampus, hypothalamus and other stress-responsive brain regions. Glucocorticoids exert their effects on the brain through genomic mechanisms that involve both glucocorticoid receptors and mineralocorticoid receptors directly binding to DNA, as well as by non-genomic mechanisms. Furthermore, glucocorticoids synergize both genomically and non-genomically with neurotransmitters, neurotrophic factors, sex hormones and other stress mediators to shape an organism's present and future responses to a stressful environment. Here, we discuss the mechanisms of glucocorticoid action in the brain and review how glucocorticoids interact with stress mediators in the context of allostasis, allostatic load and stress-induced neuroplasticity.

Comparing structural and transcriptional drug networks reveals signatures of drug activity and toxicity in transcriptional responses

We performed an integrated analysis of drug chemical structures and drug-induced transcriptional responses. We demonstrated that a network representing three-dimensional structural similarities among 5452 compounds can be used to automatically group together drugs with similar scaffolds, physicochemical parameters and mode-of-action. We compared the structural network to a network representing transcriptional similarities among a subset of 1309 drugs for which transcriptional response were available in the Connectivity Map data set. Analysis of structurally similar, but transcriptionally different drugs sharing the same MOA enabled us to detect and remove weak and noisy transcriptional responses, greatly enhancing the reliability of transcription-based approaches to drug discovery and drug repositioning. Cardiac glycosides exhibited the strongest transcriptional responses with a significant induction of pathways related to epigenetic regulation, which suggests an epigenetic mechanism of action for these drugs. Drug classes with the weakest transcriptional responses tended to induce expression of cytochrome P450 enzymes, hinting at drug-induced drug resistance. Analysis of transcriptionally similar, but structurally different drugs with unrelated MOA, led us to the identification of a 'toxic' transcriptional signature indicative of lysosomal stress (lysosomotropism) and lipid accumulation (phospholipidosis) partially masking the target-specific transcriptional effects of these drugs. We found that this transcriptional signature is shared by 258 compounds and it is associated to the activation of the transcription factor TFEB, a master regulator of lysosomal biogenesis and autophagy. Finally, we built a predictive Random Forest model of these 258 compounds based on 128 physicochemical parameters, which should help in the early identification of potentially toxic drug candidates.

Transcriptional responses to drug treatment can reveal mechanism of action and off-target effects thus enabling drug repositioning, but only if measured in the appropriate cells at clinically relevant concentrations. A team led by Diego di Bernardo and Diego Medina generated a network representing structural similarities among compounds to automatically group together drugs with similar scaffolds and MOA. By comparing the structural drug network with a transcriptional drug network based on similarities in transcriptional response, the team observed broad differences between the two. This observation led to the identification of a transcriptional signature related lysosomal stress and phospholipidosis, and a physicochemical model to identify such compounds. These results provide general guidelines to prevent erroneous conclusion when using transcriptional responses of small molecules for drug discovery and drug repositioning

Crocetin Potentiates Neurite Growth in Hippocampal Neurons and Facilitates Functional Recovery in Rats with Spinal Cord Injury

Crocetin is an ingredient of traditional Chinese medicine and has therapeutic potential in various diseases due to its pharmacological properties, such as neuroprotection, anti-oxidative stress, and anti-inflammation. These properties might benefit the treatment of spinal cord injury. In the present study, we tested the effect of crocetin on neurite growth and sensorimotor dysfunction in a rat model of spinal cord injury. We evaluated the viability of cultured hippocampal neurons with tetrazolium dye and lactate dehydrogenase assays, visualized neurites and axons with antibody staining, and monitored motor and sensorimotor functions in rats with spinal cord injury using the Basso, Beattie, and Bresnahan assay and the contact plantar placement test, respectively, and measured cytokine expression using enzyme-linked immuno-absorbent assays. We found that crocetin (1) did not alter the viability of cultured hippocampal neurons; (2) accelerated neurite growth with preference for the longest process in individual hippocampal neurons; (3) reversed the inhibition of neurite growth by chondroitin sulfate proteoglycan and NogoA; (4) facilitated the recovery of motor and sensorimotor functions after spinal cord injury; and (5) did not inhibit pro-inflammatory responses, but restored the innervation of the descending 5-HT system in injured spinal cord. Crocetin promotes neurite growth and facilitates the recovery of motor and sensorimotor functions after spinal cord injury, likely through repairing neuronal connections.

Glucocorticoid receptor expression on circulating leukocytes differs between healthy male and female adults

Introduction

The glucocorticoid receptor (GR) is a key receptor involved in inflammatory responses and is influenced by sex steroids. This study measured GR expression on circulating leukocyte subtypes in males and females.

Methods

A total of 23 healthy adults (12 female) participated in this study. GR expression was measured in leukocyte subtypes using flow cytometry. Peripheral blood mononuclear cell (PBMC) gene expression of GR (NR3C1), GR β, TGF-β1 and 2, and glucocorticoid-induced leucine zipper (GILZ) were determined by real-time polymerase chain reaction.

Results

Leukocyte GR was lower in females, particularly in granulocytes, natural killer cells, and peripheral blood mononuclear cells (p≤0.01). GR protein expression was different across leukocyte subtypes, with higher expression in eosinophils compared with granulocytes, T lymphocytes, and natural killer cells (p<0.05). There was higher gene expression of GR β in males (p=0.03).

Conclusions

This is the first study to identify sexual dimorphism in GR expression in healthy adults using flow cytometry. These results may begin to explain the sexual dimorphism seen in many diseases and sex differences in glucocorticoid responsiveness.

Protein phosphatase 5 mediates corticosteroid insensitivity in airway smooth muscle in patients with severe asthma

BACKGROUND

The mechanisms driving glucocorticoid (GC) insensitivity in patients with severe asthma are still unknown. Recent evidence suggests the existence of GC-insensitive pathways in airway smooth muscle (ASM) caused by a defect in GC receptor (GRα) function. We examined whether other mechanisms could potentially explain the reduced sensitivity of ASM cells to GC in severe asthmatics.

METHODS

Airway smooth muscle cells from healthy and severe asthmatic subjects were treated with TNF-α and responses to corticosteroids in both cohorts were compared by ELISA, immunoblot, immunohistochemistry and real-time PCR. Immunohistochemistry and flow cytometry assays were used to assess the expression of the protein phosphatase PP5 in endobronchial biopsies and ASM cells.

RESULTS

The production of CCL11 and CCL5 by TNF-α was insensitive to both fluticasone and dexamethasone in ASM cells from severe asthmatic compared to that in healthy subjects. Fluticasone-induced GRα nuclear translocation, phosphorylation at serine 211 and expression of GC-induced leucine zipper (GILZ) were significantly reduced in ASM cells from severe asthmatics compared to responses in healthy subjects. Levels of PP5 were increased in ASM cells from severe asthmatics and PP5 knockdown using siRNA restored fluticasone repressive action on chemokine production and its ability to induce GRα nuclear translocation and GRE-dependent GILZ expression. In vivo PP5 expression was also increased in the ASM bundles in endobronchial biopsies in severe asthmatics.

CONCLUSIONS

PP5-dependent impairment of GRα function represents a novel mechanism driving GC insensitivity in ASM in severe asthma.

Intrauterine Reprogramming of the Polycystic Ovary Syndrome: Evidence from a Pilot Study of Cord Blood Global Methylation Analysis

Polycystic ovary syndrome (PCOS) affects 5-15% of women. PCOS is a heterogeneous disorder displaying endocrine, metabolic, and reproductive dysfunction and cardiovascular risk manifestations. Evidence of heritability exists, but only a portion of the genetic transmission has been identified by genome-wide association studies and linkage studies, suggesting epigenetic phenomena may play a role. Evidence implicates intrauterine influences in the genesis of PCOS. This was a pilot study that aimed at identifying an epigenetic PCOS reprogramming signature by profiling the methylation of the DNA extracted from umbilical cord blood (UCB) from 12 subjects undergoing in vitro fertilization. Six subjects were anovulatory PCOS women diagnosed by Rotterdam criteria and six ovulatory non-PCOS women matched for age and body mass index. UCB was collected at delivery of the placenta; the DNA was extracted and submitted to methylation analysis. A differential methylation picture of prevalent hypomethylation affecting 918 genes was detected. Of these, 595 genes (64.8%) carried single or multiple hypomethylated CpG dinucleotides and 323 genes (35.2%) single or multiple hypermethylated CpG dinucleotides. The Ingenuity Pathway Analysis (IPA) online platform enlisted 908 of the 918 input genes and clustered 794 of them into 21 gene networks. Key features of the primary networks scored by IPA included carbohydrate and lipid metabolism, neurotransmitter signaling, cardiovascular system development and function, glycosaminoglycan signaling regulation and control of amino acid biosynthesis. Central to the network activities were genes controlling hormonal regulation (ESR1), mitochondrial activity (APP, PARK2), and glucose metabolism (INS). Regulatory pathways such as G-protein coupled receptor signaling, inositol metabolism, and inflammatory response were also highlighted. These data suggested the existence of a putative "PCOS epigenomic superpathway" with three main components: glucotoxic, lipotoxic, and inflammatory. If our results are confirmed, they hint at an epigenetic at risk PCOS "signature" may thus exist that may be identifiable at birth. Additional studies are needed to confirm the results of this pilot study.

Core level regulatory network of osteoblast as molecular mechanism for osteoporosis and treatment

To develop and evaluate the long-term prophylactic treatment for chronic diseases such as osteoporosis requires a clear view of mechanism at the molecular and systems level. While molecular signaling pathway studies for osteoporosis are extensive, a unifying mechanism is missing. In this work, we provide experimental and systems-biology evidences that a tightly connected top-level regulatory network may exist, which governs the normal and osteoporotic phenotypes of osteoblast. Specifically, we constructed a hub-like interaction network from well-documented cross-talks among estrogens, glucocorticoids, retinoic acids, peroxisome proliferator-activated receptor, vitamin D receptor and calcium-signaling pathways. The network was verified with transmission electron microscopy and gene expression profiling for bone tissues of ovariectomized (OVX) rats before and after strontium gluconate (GluSr) treatment. Based on both the network structure and the experimental data, the dynamical modeling predicts calcium and glucocorticoids signaling pathways as targets for GluSr treatment. Modeling results further reveal that in the context of missing estrogen signaling, the GluSr treated state may be an outcome that is closest to the healthy state.

Vitamin D interferes with glucocorticoid responsiveness in human peripheral blood mononuclear target cells

Glucocorticoids (GCs) are widely used in the treatment of inflammatory and autoimmune diseases; however, patients are often resistant to GC effects. Current studies indicate that vitamin D reduces the risk or modifies the course of autoimmune diseases posing vitamin D supplementation as a prevention or therapeutic option. Herein, we investigated whether vitamin D can modify the response to GCs at the molecular level. To this end, peripheral blood mononuclear cells (PBMCs) were isolated from healthy vitamin D-deficient women and incubated with either the active metabolite 1,25(OH)2D3 (VitD) for 11 days or dexamethasone (Dex) for the last 2 days in the presence or absence of VitD. Ex vivo GC sensitivity was assessed by the expression of the glucocorticoid receptor (GR) responsive gene GILZ with RT-PCR. Long-term incubation of PBMCs with VitD significantly decreased the Dex-induced augmentation of GILZ expression. Since the intracellular concentration of GR and the GR nuclear translocation are critical determinants of GC sensitivity, we next evaluated the effect of VitD on these factors. RT-PCR and western-blot analysis revealed that VitD reduced the expression of GR. This effect was abolished by the HDAC-specific inhibitor trichostatin A, implying that HDAC was implicated in this effect. Moreover, NCoR1 mRNA was significantly decreased upon treatment with VitD either alone or as pre-treatment to Dex, suggesting that a possible increase in expression of this co-repressor was not involved. In addition, immunofluorescence analysis showed that VitD hindered the Dex-induced GRα nuclear translocation, an effect verified by subcellular fractionation and western-blot experiments. To further explore the underpinning mechanism, we examined the potential of VitD to: (1) strengthen the FK506-binding protein 5 (FKBP5) negative feedback loop and (2) modify the phosphorylation status of GR. Remarkably, VitD decreased FKBP5 expression and decreased phosphorylation at Ser211, while enhancing phosphorylation of GR at Ser203. Overall, VitD decreases the ex vivo GC sensitivity and this effect is, at least in part, attributed both to decrease of GR expression owing to a mechanism that engages HDAC and inhibition of GR translocation to nucleus via differential modulation of the phosphorylation state of GR. Our study provides, for the first time, evidence that long-term action of VitD induces GC resistance in PBMCs from healthy volunteers and offers a possible mechanistic basis for VitD-triggered attenuation of GC effects.

Abnormal corticosteroid signalling in airway smooth muscle: mechanisms and perspectives for the treatment of severe asthma

Growing in vivo evidence supports the concept that airway smooth muscle produces various immunomodulatory factors that could contribute to asthma pathogenesis via the regulation of airway inflammation, airway narrowing and remodelling. Targeting ASM using bronchial thermoplasty has provided undeniable clinical benefits for patients with uncontrolled severe asthma who are refractory to glucocorticoid therapy. The present review will explain why the failure of glucocorticoids to adequately manage patients with severe asthma could derive from their inability to affect the immunomodulatory potential of ASM. We will support the view that ASM sensitivity to glucocorticoid therapy can be blunted in severe asthma and will describe some of the factors and mechanisms that could be responsible for glucocorticoid insensitivity.

Modifications to glucocorticoid and progesterone receptors alter cell fate in breast cancer

Steroid hormone receptors (SRs) are heavily posttranslationally modified by the reversible addition of a variety of molecular moieties, including phosphorylation, acetylation, methylation, SUMOylation, and ubiquitination. These rapid and dynamic modifications may be combinatorial and interact (i.e. may be sequential, complement, or oppose each other), creating a vast array of uniquely modified receptor subspecies that allow for diverse receptor behaviors that enable highly sensitive and context-dependent hormone action. For example, in response to hormone or growth factor membrane-initiated signaling events, posttranslational modifications (PTMs) to SRs alter protein-protein interactions that govern the complex process of promoter or gene-set selection coupled to transcriptional repression or activation. Unique phosphorylation events allow SRs to associate or disassociate with specific cofactors that may include pioneer factors and other tethering partners, which specify the resulting transcriptome and ultimately change cell fate. The impact of PTMs on SR action is particularly profound in the context of breast tumorigenesis, in which frequent alterations in growth factor-initiated signaling pathways occur early and act as drivers of breast cancer progression toward endocrine resistance. In this article, with primary focus on breast cancer relevance, we review the mechanisms by which PTMs, including reversible phosphorylation events, regulate the closely related SRs, glucocorticoid receptor and progesterone receptor, allowing for precise biological responses to ever-changing hormonal stimuli.

Sexual Dimorphism in Circadian Physiology Is Altered in LXRα Deficient Mice

The mammalian circadian timing system coordinates key molecular, cellular and physiological processes along the 24-h cycle. Accumulating evidence suggests that many clock-controlled processes display a sexual dimorphism. In mammals this is well exemplified by the difference between the male and female circadian patterns of glucocorticoid hormone secretion and clock gene expression. Here we show that the non-circadian nuclear receptor and metabolic sensor Liver X Receptor alpha (LXRα) which is known to regulate glucocorticoid production in mice modulates the sex specific circadian pattern of plasma corticosterone. Lxrα^-/- males display a blunted corticosterone profile while females show higher amplitude as compared to wild type animals. Wild type males are significantly slower than females to resynchronize their locomotor activity rhythm after an 8 h phase advance but this difference is abrogated in Lxrα^-/- males which display a female-like phenotype. We also show that circadian expression patterns of liver 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and Phosphoenolpyruvate carboxykinase (Pepck) differ between sexes and are differentially altered in Lxrα^-/- animals. These changes are associated with a damped profile of plasma glucose oscillation in males but not in females. Sex specific alteration of the insulin and leptin circadian profiles were observed in Lxα^-/- females and could be explained by the change in corticosterone profile. Together this data indicates that LXRα is a determinant of sexually dimorphic circadian patterns of key physiological parameters. The discovery of this unanticipated role for LXRα in circadian physiology underscores the importance of addressing sex differences in chronobiology studies and future LXRα targeted therapies.

Beyond the C18 frontier: Androgen and glucocorticoid metabolism in breast cancer tissues: The role of non-typical steroid hormones in breast cancer development and progression

Breast cancer's hormonal dependence is well known and has been so for a long time. However in the last two decades great advances have been made in understanding the local metabolism of steroids within tissue. In the form of aromatase inhibition this is already one of the mainstays of breast cancer therapy. This review aims to summarise briefly what is known in terms of the metabolism of C18 steroids but perhaps more importantly to touch on the new developments regarding the importance of the metabolism of androgens and glucocorticoids in breast tissue. It is our hope that this review should provide the reader with a "birds eye view" of the current state of knowledge regarding localised steroid metabolism in the breast.

Selective activators of protein phosphatase 5 target the auto-inhibitory mechanism

This paper describes the identification of compounds, which stimulate the activity of the protein phosphatase PPH-5 and addresses the influence of the identified compounds on the enzymatic properties and the potential mechanism of their action.

Protein phosphatase 5 (PP5) is an evolutionary conserved serine/threonine phosphatase. Its dephosphorylation activity modulates a diverse set of cellular factors including protein kinases and the microtubule-associated tau protein involved in neurodegenerative disorders. It is auto-regulated by its heat-shock protein (Hsp90)-interacting tetratricopeptide repeat (TPR) domain and its C-terminal α-helix. In the present study, we report the identification of five specific PP5 activators [PP5 small-molecule activators (P5SAs)] that enhance the phosphatase activity up to 8-fold. The compounds are allosteric modulators accelerating efficiently the turnover rate of PP5, but do barely affect substrate binding or the interaction between PP5 and the chaperone Hsp90. Enzymatic studies imply that the compounds bind to the phosphatase domain of PP5. For the most promising compound crystallographic comparisons of the apo PP5 and the PP5–P5SA-2 complex indicate a relaxation of the auto-inhibited state of PP5. Residual electron density and mutation analyses in PP5 suggest activator binding to a pocket in the phosphatase/TPR domain interface, which may exert regulatory functions. These compounds thus may expose regulatory mechanisms in the PP5 enzyme and serve to develop optimized activators based on these scaffolds.

Reduced glucocorticoid receptor expression predicts bladder tumor recurrence and progression

OBJECTIVES

To assess the levels of glucocorticoid receptor (GR) expression in bladder tumors because the status and its prognostic value remain largely unknown.

METHODS

We immunohistochemically stained for GR in bladder tumor and matched non-neoplastic bladder tissue specimens.

RESULTS

Overall, GR was positive in 129 (87%) of 149 urothelial tumors, which was significantly (P=.026) lower than in non-neoplastic urothelium (90 [96%] of 94). Forty-two (79%) of 53 low-grade tumors vs 45 (47%) of 96 high-grade carcinomas (P<.001) and 61 (73%) of 84 non-muscle-invasive (NMI) tumors vs 26 (40%) of 65 muscle-invasive (MI) carcinomas (P<.001) were moderately to strongly immunoreactive for GR. Kaplan-Meier and log-rank tests revealed that loss or weak positivity of GR significantly or marginally correlated with recurrence of NMI tumors (P=.025), progression of MI tumors (P=.082), and cancer-specific survival of MI tumors (P=.067). Multivariate analysis identified low GR expression as a strong predictor for recurrence of NMI tumors (P=.034).

CONCLUSIONS

GR expression was downregulated in bladder tumors compared with nonneoplastic bladder tumors and in high-grade/MI tumors compared with low-grade/NMI tumors. Decreased expression of GR, as an independent prognosticator, predicted recurrence of NMI tumors. These results support experimental evidence suggesting an inhibitory role of GR signals in bladder cancer outgrowth.

Anti-inflammatory and corticosteroid-enhancing actions of vitamin D in monocytes of patients with steroid-resistant and those with steroid-sensitive asthma

BACKGROUND

Vitamin D is known for its anti-inflammatory effects.

OBJECTIVE

Vitamin D regulation of responses in patients with steroid-resistant (SR) versus steroid-sensitive (SS) asthma has not been studied.

METHODS

Peripheral blood cells from 11 patients with SR asthma and 8 patients with SS asthma were preincubated with 1,25-dihydroxyvitamin D (1,25[OH]2D [VitD]), followed by dexamethasone (DEX) treatment and LPS stimulation. LPS-induced phosphorylated p38 mitogen-activated protein kinase (p-p38) in monocytes was examined by means of flow cytometry. Mitogen-activated protein kinase phosphatase-1 (MKP-1) mRNA expression, which inhibits p-p38, was analyzed by means of real-time PCR. Glucocorticoid receptor (GR) binding and histone H4 acetylation in the glucocorticoid response element of the MKP-1 promoter in monocytes were analyzed by means of chromatin immunoprecipitation.

RESULTS

DEX significantly inhibited LPS-induced p-p38 in monocytes from patients with SS asthma but not those from patients with SR asthma (P < .01). VitD inhibited LPS-induced p-p38 in monocytes from both patient groups (P < .01) but enhanced DEX suppression of LPS-induced p-p38 only in monocytes from patients with SS asthma (P < .01). VitD induced MKP-1 expression and enhanced DEX induction of MKP-1 in both patients with SS asthma and patients with SR asthma. VitD/DEX-induced MKP-1 mRNA levels remained significantly lower in monocytes from patients with SR asthma (P < .05). DEX-stimulated recruitment of GR and histone H4 acetylation at the glucocorticoid response element 4.6 kbp upstream of the MKP-1 gene were significantly lower in monocytes from patients with SR asthma compared with those from patients with SS asthma. VitD pretreatment enhanced DEX-induced GR binding and histone acetylation in monocytes from both patient groups. However, GR binding and histone H4 acetylation remained significantly lower in monocytes from patients with SR asthma.

CONCLUSION

VitD demonstrated anti-inflammatory and corticosteroid-enhancing effects in monocytes of patients with SR asthma and patients with SS asthma. However, the responses to corticosteroids in patients with SR asthma remained significantly lower than those in patients with SS asthma.

The effects of airway microbiome on corticosteroid responsiveness in asthma

RATIONALE

The role of airway microbiome in corticosteroid response in asthma is unknown.

OBJECTIVES

To examine airway microbiome composition in patients with corticosteroid-resistant (CR) asthma and compare it with patients with corticosteroid-sensitive (CS) asthma and normal control subjects and explore whether bacteria in the airways of subjects with asthma may direct alterations in cellular responses to corticosteroids.

METHODS

16S rRNA gene sequencing was performed on bronchoalveolar lavage (BAL) samples of 39 subjects with asthma and 12 healthy control subjects. In subjects with asthma, corticosteroid responsiveness was characterized, BAL macrophages were stimulated with pathogenic versus commensal microorganisms, and analyzed by real-time polymerase chain reaction for the expression of corticosteroid-regulated genes and cellular p38 mitogen-activated protein kinase (MAPK) activation.

MEASUREMENTS AND MAIN RESULTS

Of the 39 subjects with asthma, 29 were CR and 10 were CS. BAL microbiome from subjects with CR and CS asthma did not differ in richness, evenness, diversity, and community composition at the phylum level, but did differ at the genus level, with distinct genus expansions in 14 subjects with CR asthma. Preincubation of asthmatic airway macrophages with Haemophilus parainfluenzae, a uniquely expanded potential pathogen found only in CR asthma airways, resulted in p38 MAPK activation, increased IL-8 (P < 0.01), mitogen-activated kinase phosphatase 1 mRNA (P < 0.01) expression, and inhibition of corticosteroid responses (P < 0.05). This was not observed after exposure to commensal bacterium Prevotella melaninogenica. Inhibition of transforming growth factor-β-associated kinase-1 (TAK1), upstream activator of MAPK, but not p38 MAPK restored cellular sensitivity to corticosteroids.

CONCLUSIONS

A subset of subjects with CR asthma demonstrates airway expansion of specific gram-negative bacteria, which trigger TAK1/MAPK activation and induce corticosteroid resistance. TAK1 inhibition restored cellular sensitivity to corticosteroids.

Exposure to road traffic and railway noise and postmenopausal breast cancer: A cohort study

Exposure to traffic noise may result in stress and sleep disturbances. Studies on self-reported sleep duration and breast cancer risk have found inconsistent results. In a population-based Danish cohort of 29,875 women aged 50-64 years at enrolment in 1993-1997, we identified 1219 incident, postmenopausal breast cancer cases during follow-up through 2010. Mean follow-up time was 12.3 years. Road traffic and railway noise was calculated for all present and historical residential addresses from 1987 to 2010. We used Cox proportional hazard model for analyses and adjusted for hormone replacement therapy use, parity, alcohol consumption and other potential confounders. We found no overall association between residential road traffic or railway noise and breast cancer risk. Among women with estrogen receptor negative breast cancer, a 10-dB higher level of road traffic noise (continuous scale) during the previous 1, 5 and 10 years were associated with 28% (95% CI: 1.04-1.56), 23% (95% CI: 1.00-1.51) and 20% (95% CI: 0.97-1.48) higher risks of estrogen receptor negative breast cancer, respectively, in fully adjusted models. Similarly, a 10-dB increase in railway noise (1-year mean at diagnosis address) increased risk for estrogen receptor negative breast cancer by 38% (95% CI: 1.01-1.89). There was no association between road traffic or railway noise and estrogen receptor positive breast cancer. In conclusion, these results suggest that residential road traffic and railway noise may increase risk of estrogen receptor negative breast cancer. As the first study on traffic noise and breast cancer results should be treated with caution.

A role for glucocorticoids in stress-impaired reproduction: beyond the hypothalamus and pituitary

In addition to the well-characterized role of the sex steroid receptors in regulating fertility and reproduction, reproductive events are also mediated by the hypothalamic-pituitary-adrenal axis in response to an individual's environment. Glucocorticoid secretion in response to stress contributes to the well-characterized suppression of the hypothalamic-pituitary-gonadal axis through central actions in the hypothalamus and pituitary. However, both animal and in vitro studies indicate that other components of the reproductive system are also regulated by glucocorticoids. Furthermore, in the absence of stress, it appears that homeostatic glucocorticoid signaling plays a significant role in reproduction and fertility in all tissues comprising the hypothalamic-pituitary-gonadal axis. Indeed, as central regulators of the immune response, glucocorticoids are uniquely poised to integrate an individual's infectious, inflammatory, stress, nutritional, and metabolic status through glucocorticoid receptor signaling in target tissues. Endocrine signaling between tissues regulating the immune and stress response and those determining reproductive status provides an evolutionary advantage, facilitating the trade-off between reproductive investment and offspring fitness. This review focuses on the actions of glucocorticoids in tissues important for fertility and reproduction, highlighting recent studies that show glucocorticoid signaling plays a significant role throughout the hypothalamic-pituitary-gonadal axis and characterizing these effects as permissive or inhibitory in terms of facilitating reproductive success.

A preliminary evaluation of leukocyte phospho-glucocorticoid receptor as a potential biomarker of depressogenic vulnerability in healthy adults

The mechanism of maladaptive chronic stress response involves altered phosphorylation of the glucocorticoid receptor (GR). In this study, we investigated if important depressogenic vulnerability factors, such as neuroticism and self-reports of negative affective states, may be associated with alterations in levels of the GR and GR phosphoisoforms in peripheral blood mononuclear cells (PBMC) of healthy adults. In 21 women and 16 men we evaluated PMBC levels of total GR (tGR), GR phosphorylated at serine 211 (pGR-S211) and serine 226 (pGR-S226) and correlated these data with personality traits and current reports of stress, anxiety and depression. Also, we assessed plasma cortisol levels in all tested subjects. Our results showed that in women nuclear pGR-S226 was positively correlated with neuroticism and current reports of depression, anxiety and stress, while the ratio of nuclear pGR-S211/pGR-S226 was negatively correlated with reports of depression. None of the aforementioned correlations were significant in men. No significant relations between cortisol levels and any of GR parameters were observed. These preliminary findings highlight the value of GR phosphorylation-related research in identifying molecular biomarkers of depressogenic vulnerability, at least in women.

Genetic disruption of protein phosphatase 5 in mice prevents high-fat diet feeding-induced weight gain

The role of serine/threonine protein phosphatase 5 (PP5) in the development of obesity and insulin resistance associated with high-fat diet-feeding (HFD) was examined using PP5-deficient mice (Ppp5c(-/-)). Despite similar caloric intake, Ppp5c(-/-) mice on HFD gained markedly less weight and did not accumulate visceral fat compared to wild-type littermates (Ppp5c(+/+)). On a control diet, Ppp5c(-/-) mice had markedly improved glucose control compared to Ppp5c(+/+) mice, an effect diminished by HFD. However, even after 10 weeks of HFD glucose control in Ppp5c(-/-) mice was similar to that observed in Ppp5c(+/+) mice on the control diet. Thus, PP5 deficiency confers protection against HFD-induced weight gain in mice.

Functional KCa3.1 channels regulate steroid insensitivity in bronchial smooth muscle cells

Identifying the factors responsible for relative glucocorticosteroid (GC) resistance present in patients with severe asthma and finding tools to reverse it are of paramount importance. In asthma we see in vivo evidence of GC-resistant pathways in airway smooth muscle (ASM) bundles that can be modeled in vitro by exposing cultured ASM cells to TNF-α/IFN-γ. This action drives GC insensitivity via protein phosphatase 5-dependent impairment of GC receptor phosphorylation. In this study, we investigated whether KCa3.1 ion channels modulate the activity of GC-resistant pathways using our ASM model of GC insensitivity. Immunohistochemical staining of endobronchial biopsies revealed that KCa3.1 channels are localized to the plasma membrane and nucleus of ASM in both healthy controls and asthmatic patients, irrespective of disease severity. Western blot assays and immunofluorescence staining confirmed the nuclear localization of KCa3.1 channels in ASM cells. The functional importance of KCa3.1 channels in the regulation of GC-resistant chemokines induced by TNF-α/IFN-γ was assessed using complementary inhibitory strategies, including KCa3.1 blockers (TRAM-34 and ICA-17043) or KCa3.1-specific small hairpin RNA delivered by adenoviruses. KCa3.1 channel blockade led to a significant reduction of fluticasone-resistant CX3CL1, CCL5, and CCL11 gene and protein expression. KCa3.1 channel blockade also restored fluticasone-induced GC receptor-α phosphorylation at Ser(211) and transactivation properties via the suppression of cytokine-induced protein phosphatase 5 expression. The effect of KCa3.1 blockade was evident in ASM cells from both healthy controls and asthmatic subjects. In summary, KCa3.1 channels contribute to the regulation of GC-resistant inflammatory pathways in ASM cells: blocking KCa3.1 channels may enhance corticosteroid activity in severe asthma.

Respiratory syncytial virus (RSV) suppression of glucocorticoid receptor phosphorylation does not account for repression of transactivation

Respiratory syncytial virus (RSV)-induced bronchiolitis in infants, although inflammatory in nature, is not responsive to glucocorticoids. We have recently shown that RSV-infected lung epithelial cells have impaired glucocorticoid receptor (GR)-mediated transactivation. In this study, we show that the N-terminal region of GR is required for RSV repression of GR transactivation and that RSV infection of lung epithelial cells reduces ligand-dependent GR phosphorylation at serine 211 and serine 226. However, we also show that these changes in GR phosphorylation do not account for the RSV repression of GR transactivation suggesting other regions of the GR N-terminus must also be involved.

Chaperone-interacting TPR proteins in Caenorhabditis elegans

The ATP-hydrolyzing molecular chaperones Hsc70/Hsp70 and Hsp90 bind a diverse set of tetratricopeptide repeat (TPR)-containing cofactors via their C-terminal peptide motifs IEEVD and MEEVD. These cochaperones contribute to substrate turnover and confer specific activities to the chaperones. Higher eukaryotic genomes encode a large number of TPR-domain-containing proteins. The human proteome contains more than 200 TPR proteins, and that of Caenorhabditis elegans, about 80. It is unknown how many of them interact with Hsc70 or Hsp90. We systematically screened the C. elegans proteome for TPR-domain-containing proteins that likely interact with Hsc70 and Hsp90 and ranked them due to their similarity with known chaperone-interacting TPRs. We find C. elegans to encode many TPR proteins, which are not present in yeast. All of these have homologs in fruit fly or humans. Highly ranking uncharacterized open reading frames C33H5.8, C34B2.5 and ZK370.8 may encode weakly conserved homologs of the human proteins RPAP3, TTC1 and TOM70. C34B2.5 and ZK370.8 bind both Hsc70 and Hsp90 with low micromolar affinities. Mutation of amino acids involved in EEVD binding disrupts the interaction. In vivo, ZK370.8 is localized to mitochondria in tissues with known chaperone requirements, while C34B2.5 colocalizes with Hsc70 in intestinal cells. The highest-ranking open reading frame with non-conserved EEVD-interacting residues, F52H3.5, did not show any binding to Hsc70 or Hsp90, suggesting that only about 15 of the TPR-domain-containing proteins in C. elegans interact with chaperones, while the many others may have evolved to bind other ligands.

The serine/threonine phosphatase PPM1B (PP2Cβ) selectively modulates PPARγ activity

Reversible phosphorylation is a widespread molecular mechanism to regulate the function of cellular proteins, including transcription factors. Phosphorylation of the nuclear receptor PPARγ (peroxisome-proliferator-activated receptor γ) at two conserved serine residue (Ser(112) and Ser(273)) results in an altered transcriptional activity of this transcription factor. So far, only a very limited number of cellular enzymatic activities has been described which can dephosphorylate nuclear receptors. In the present study we used immunoprecipitation assays coupled to tandem MS analysis to identify novel PPARγ-regulating proteins. We identified the serine/threonine phosphatase PPM1B [PP (protein phosphatase), Mg(2+)/Mn(2+) dependent, 1B; also known as PP2Cβ] as a novel PPARγ-interacting protein. Endogenous PPM1B protein is localized in the nucleus of mature 3T3-L1 adipocytes where it can bind to PPARγ. Furthermore we show that PPM1B can directly dephosphorylate PPARγ, both in intact cells and in vitro. In addition PPM1B increases PPARγ-mediated transcription via dephosphorylation of Ser(112). Finally, we show that knockdown of PPM1B in 3T3-L1 adipocytes blunts the expression of some PPARγ target genes while leaving others unaltered. These findings qualify the phosphatase PPM1B as a novel selective modulator of PPARγ activity.

Vitamin D enhances glucocorticoid action in human monocytes: involvement of granulocyte-macrophage colony-stimulating factor and mediator complex subunit 14

Vitamin D (VitD) is now recognized for its pleiotrophic roles in regulating immune function. VitD interaction with other steroid receptor superfamily receptors in peripheral blood mononuclear cells is poorly understood. In the current study, we demonstrate that VitD enhanced glucocorticoid (GC) responses in human peripheral blood mononuclear cells because it stimulated GC induction of mitogen-activated protein kinase phosphatase-1 (MKP-1) and enhanced GC inhibition of LPS-induced IL-6. These VitD effects were abolished in purified CD14(+) and CD14(-) cells but were recovered in CD14(+) cells co-cultured with CD14(-) cells separated by tissue culture inserts. GM-CSF, found in culture supernatants from CD14(-) cells, was shown to mediate VitD enhancement of GC-induced MKP-1 production in monocytes via increased production of mediator complex subunit 14 (MED14). Recruitment of VitD receptor and MED14, 4.7 kbp upstream of the human MKP-1 gene transcription start site, enhanced binding of glucocorticoid receptor and histone H4 acetylation at the 4.6-kbp glucocorticoid response element of the MKP-1 promoter in the presence of GM-CSF in U937 cells. Knockdown of MED14 abolished VitD-mediated enhancement of GC-induced MKP-1 production. These data demonstrate VitD-mediated stimulation of GC anti-inflammatory effects in human monocytes and identify a role for GM-CSF and MED14 as mediators of this process.

Early life adversity as a risk factor for visceral pain in later life: importance of sex differences

A history of early life adversity (ELA) has health-related consequences that persist beyond the initial maltreatment and into adulthood. Childhood adversity is associated with abnormal glucocorticoid signaling within the hypothalamic-pituitary-adrenal (HPA) axis and the development of functional pain disorders such as the irritable bowel syndrome (IBS). IBS and many adult psychopathologies are more frequently diagnosed in women, and ovarian hormones have been shown to modulate pain sensitivity. Therefore, the sexually dimorphic effects of ELA and the role of ovarian hormones in visceral pain perception represent critical research concepts to enhance our understanding of the etiology of IBS. In this review, we discuss current animal models of ELA and the potential mechanisms through which ovarian hormones modulate the HPA axis to alter nociceptive signaling pathways and induce functionally relevant changes in pain behaviors following ELA.