Antagonism of glucocorticoid receptor transactivity and cell growth inhibition by transforming growth factor-beta through AP-1-mediated transcriptional repression

Candidate Genes and Gene Networks Change with Age in Japanese Black Cattle by Blood Transcriptome Analysis

Age is an important physiological factor that affects the metabolism and immune function of beef cattle. While there have been many studies using the blood transcriptome to study the effects of age on gene expression, few have been reported on beef cattle. To this end, we used the blood transcriptomes of Japanese black cattle at different ages as the study subjects and screened 1055, 345, and 1058 differential expressed genes (DEGs) in the calf vs. adult, adult vs. old, and calf vs. old comparison groups, respectively. The weighted co-expression network consisted of 1731 genes. Finally, blue, brown, and yellow age-specific modules were obtained, in which genes were enriched in signaling pathways related to growth and development and immune metabolic dysfunction, respectively. Protein-protein interaction (PPI) analysis showed gene interactions in each specific module, and 20 of the highest connectivity genes were chosen as potential hub genes. Finally, we identified 495, 244, and 1007 genes by exon-wide selection signature (EWSS) analysis of different comparison groups. Combining the results of hub genes, we found that VWF, PARVB, PRKCA, and TGFB1I1 could be used as candidate genes for growth and development stages of beef cattle. CORO2B and SDK1 could be used as candidate marker genes associated with aging. In conclusion, by comparing the blood transcriptome of calves, adult cattle, and old cattle, the candidate genes related to immunity and metabolism affected by age were identified, and the gene co-expression network of different age stages was constructed. It provides a data basis for exploring the growth, development, and aging of beef cattle.

Low dose TGF-β1 can improve vohwinkel syndrome by promoting the proliferation of keratinocytes

Vohwinkel syndrome (VS) is a very rare autosomal dominant disorder that can cause disability and deformity in severe cases. Mutations of the LOR (loricrin) and GJB2 (Cx26) genes have been found in VS so far. Many studies have indicated that the differentiation and growth of epidermal keratinocytes are regulated by mutant Cx26, and it may explain the pathogenesis of VS. It has been found that transforming growth factor β1 (TGF-β1) expression was lower in G130V (OE1) and D66H (OE2) mutant keratinocytes in the VS model with GJB2 mutation as compared to normal keratinocytes (NC). TGF-β is a cytokine involved in the regulation of processes like cell proliferation and differentiation in different types of cells. At present, many in vitro studies focus on TGF- β 1 inhibition of keratinocyte growth.However, the relationship between TGF-β1 and VS remains unknown. This study aimed at elucidating the role and potential pathogenic mechanism of TGF-β in VS. The results indicated that the down-regulation expression of TGF-β1 in VS was linked to cell proliferation inhibition through p-Smad3/c-myc. In contrast, low-dose TGF-β1 treatment of VS keratinocytes can improve their proliferation inhibition and up-regulate the expression Cyclin D1. This suggests that low doses of TGF-β1 can improve the proliferation of VS and provide new insights into its treatment.

Low-dose curcumin stimulates proliferation of rat embryonic neural stem cells through glucocorticoid receptor and STAT3

AIMS

This study was to determine whether curcumin had any effect on the proliferation of neural stem cell (NSC), analyze the expression of glucocorticoid receptor (GR), signal transducer and activator of transcription 3 (STAT3), and Notch1 at transcription and protein level, and discuss the related mechanisms.

METHODS AND RESULTS

NSCs were harvested from E15 SD rat brain and cultured. All experiments were performed at the second passage. Cell cytotoxicity, cell viability, and proliferation assays were used to figure out the optimal concentration of curcumin, which can be used for the protein and mRNA studies. The results showed that by downregulation of GR and STAT3 expression, 0.5 μmol L^-1 curcumin exhibited the most pronounced effect in promoting the proliferation of NSCs, which were also induced by antagonists of GR and STAT3, but was inhibited by GR agonist.

CONCLUSION

This study shows that low-dose curcumin stimulates the proliferation of NSCs, which is probably by inhibiting the mRNA and protein expressions of GR and directly or indirectly regulating the STAT3 via the synergistic effect of GR and STAT3 pathways and its related signal pathways.

Cucurmin, anticancer, & antitumor perspectives: A comprehensive review

Cucurmin, a naturally yellow component isolated from turmeric, ability to prevent various life-style related disorders. The current review article mainly emphasizes on different anticancer perspectives of cucurmin, i.e., colon, cervical, uterine, ovarian, prostate head and neck, breast, pulmonary, stomach and gastric, pancreatic, bladder oral, oesophageal, and bone cancer. It holds a mixture of strong bioactive molecule known as cucurminoids that has ability to reduce cancer/tumor at initial, promotion and progression stages of tumor development. In particular, these compounds block several enzymes required for the growth of tumors and may therefore involve in tumor treatments. Moreover, it modulates an array of cellular progressions, i.e., nitric oxide synthetase activity, protein kinase C activity, epidermal growth factor (EGF) receptor intrinsic kinase activity, nuclear factor kappa (NF-kB) activity, inhibiting lipid peroxidation and production of reactive oxygen species. However, current manuscript summarizes most of the recent investigations of cucurmin but still further research should be conducted to explore the role of curcumin to mitigate various cancers.

Transforming Growth Factor Beta is regulated by a Glucocorticoid-Dependent Mechanism in Denervation Mouse Bone

Bone growth and remodeling is inhibited by denervation in adults and children, resulting in alterations of linear growth and bone mass and increased risk for osteoporosis and pathologic fractures. Transforming growth factor beta (TGF-β) isoforms are a key group of growth factors that enhance bone formation. To explore the relation between denervation-induced reduction of bone formation and TGF-β gene expression, we measured mRNA levels of TGF-β in denervation mouse bone and found decreased mRNA levels of TGF-β1, TGF-β2 and TGF-β3. These changes were accompanied by diminishing weight loss, bone mineral density (BMD), trabecular thickness, trabecular separation and trabecular number of femur and lumbar, serum osteocalcin, total calcium, intact parathyroid hormone, and increased serum C telopeptide. Recombinant human TGF-β1 (rhTGF-β1) prevented denervation-induced reduction of BMD further supporting our hypothesis that denervation-induced reduction of bone formation is a result of inhibition of TGF-β gene expression. In addition, antiprogestins RU 38486 blunted the denervation-induced decrease in mRNA levels of TGF-β group, while dexamethasone (DEX) decreased TGF-β group mRNA levels in normal mice. Furthermore, the denervated-mice exhibited a threefold increase in plasma corticosterone. These results suggest that denervation-induced reduction of bone formation may be regulated by glucocorticoids via inhibition of TGF-β gene expression at least in part.

The mechanism and significance of synergistic induction of the expression of plasminogen activator inhibitor-1 by glucocorticoid and transforming growth factor beta in human ovarian cancer cells

Plasminogen activator inhibitor-1 (PAI-1) plays a key role in tissue remodeling and tumor development by suppression of plasminogen activator function. Glucocorticoids (GCs) and transforming growth factor beta (TGF-β) signal pathways cross-talk to regulate gene expression, but the mechanism is poorly understood. Here we investigated the mechanism and significance of co-regulation of PAI-1 by TGF-β and dexamethasone (DEX), a synthetic glucocorticoid in ovarian cancer cells. We found that TGF-β and DEX showed rapidly synergistic induction of PAI-1 expression, which contributed to the early pro-adhesion effects. The synergistic induction effect was accomplished by several signal pathways, including GC receptor (GR) pathway and TGF-β-activated p38MAPK, ERK and Smad3 pathways. TGF-β-activated p38MAPK and ERK pathways cross-talked with GR pathway to augment the expression of PAI-1 through enhancing DEX-induced GR phosphorylation at Ser211 in ovarian cancer cells. These findings reveal possible novel mechanisms by which TGF-β pathways cooperatively cross-talk with GR pathway to regulate gene expression.

Dual role for glucocorticoids in cardiomyocyte hypertrophy and apoptosis

Glucocorticoids and their synthetic derivatives are known to alter cardiac function in vivo; however, the nature of these effects and whether glucocorticoids act directly on cardiomyocytes are poorly understood. To explore the role of glucocorticoid signaling in the heart, we used rat embryonic H9C2 cardiomyocytes and primary cardiomyocytes as model systems. Dexamethasone (100 nm) treatment of cardiomyocytes caused a significant increase in cell size and up-regulated the expression of cardiac hypertrophic markers, including atrial natriuretic factor, β-myosin heavy chain, and skeletal muscle α-actin. In contrast, serum deprivation and TNFα exposure triggered cardiomyocyte apoptosis, and these apoptotic effects were inhibited by dexamethasone. Both the hypertrophic and anti-apoptotic actions of glucocorticoids were abolished by the glucocorticoid receptor (GR) antagonist RU486 and by short hairpin RNA-mediated GR depletion. Blocking the activity of the mineralocorticoid receptor had no effect on these glucocorticoid-dependent cardiomyocyte responses. Aldosterone (1 μm) activation of GR also promoted cardiomyocyte hypertrophy and cell survival. To elucidate the mechanism of the dual glucocorticoid actions, a genome-wide microarray was performed on H9C2 cardiomyocytes treated with vehicle or dexamethasone in the absence or presence of serum. Serum dramatically influenced the transcriptome regulated by GR, revealing potential glucocorticoid signaling mediators in both cardiomyocyte hypertrophy and apoptosis. These studies reveal a direct and dynamic role for glucocorticoids and GR signaling in the modulation of cardiomyocyte function.

New drug targets in depression: inflammatory, cell-mediated immune, oxidative and nitrosative stress, mitochondrial, antioxidant, and neuroprogressive pathways. And new drug candidates--Nrf2 activators and GSK-3 inhibitors

This paper reviews new drug targets in the treatment of depression and new drug candidates to treat depression. Depression is characterized by aberrations in six intertwined pathways: (1) inflammatory pathways as indicated by increased levels of proinflammatory cytokines, e.g. interleukin-1 (IL-1), IL-6, and tumour necrosis factor α. (2) Activation of cell-mediated immune pathways as indicated by an increased production of interferon γ and neopterin. (3) Increased reactive oxygen and nitrogen species and damage by oxidative and nitrosative stress (O&NS), including lipid peroxidation, damage to DNA, proteins and mitochondria. (4) Lowered levels of key antioxidants, such as coenzyme Q10, zinc, vitamin E, glutathione, and glutathione peroxidase. (5) Damage to mitochondria and mitochondrial DNA and reduced activity of respiratory chain enzymes and adenosine triphosphate production. (6) Neuroprogression, which is the progressive process of neurodegeneration, apoptosis, and reduced neurogenesis and neuronal plasticity, phenomena that are probably caused by inflammation and O&NS. Antidepressants tend to normalize the above six pathways. Targeting these pathways has the potential to yield antidepressant effects, e.g. using cytokine antagonists, minocycline, Cox-2 inhibitors, statins, acetylsalicylic acid, ketamine, ω3 poly-unsaturated fatty acids, antioxidants, and neurotrophic factors. These six pathways offer new, pathophysiologically guided drug targets suggesting that novel therapies could be developed that target these six pathways simultaneously. Both nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activators and glycogen synthase kinase-3 (GSK-3) inhibitors target the six above-mentioned pathways. GSK-3 inhibitors have antidepressant effects in animal models of depression. Nrf2 activators and GSK-3 inhibitors have the potential to be advanced to phase-2 clinical trials to examine whether they augment the efficacy of antidepressants or are useful as monotherapy.

The new '5-HT' hypothesis of depression: cell-mediated immune activation induces indoleamine 2,3-dioxygenase, which leads to lower plasma tryptophan and an increased synthesis of detrimental tryptophan catabolites (TRYCATs), both of which contribute to the onset of depression

This paper reviews the body of evidence that not only tryptophan and consequent 5-HT depletion, but also induction of indoleamine 2,3-dioxygenase (IDO) and the detrimental effects of tryptophan catabolites (TRYCATs) play a role in the pathophysiology of depression. IDO is induced by interferon (IFN)γ, interleukin-6 and tumor necrosis factor-α, lipopolysaccharides and oxidative stress, factors that play a role in the pathophysiology of depression. TRYCATs, like kynurenine and quinolinic acid, are depressogenic and anxiogenic; activate oxidative pathways; cause mitochondrial dysfunctions; and have neuroexcitatory and neurotoxic effects that may lead to neurodegeneration. The TRYCAT pathway is also activated following induction of tryptophan 2,3-dioxygenase (TDO) by glucocorticoids, which are elevated in depression. There is evidence that activation of IDO reduces plasma tryptophan and increases TRYCAT synthesis in depressive states and that TDO activation may play a role as well. The development of depressive symptoms during IFNα-based immunotherapy is strongly associated with IDO activation, increased production of detrimental TRYCATs and lowered levels of tryptophan. Women show greater IDO activation and TRYCAT production following immune challenge than men. In the early puerperium, IDO activation and TRYCAT production are associated with the development of affective symptoms. Clinical depression is accompanied by lowered levels of neuroprotective TRYCATs or increased levels or neurotoxic TRYCATs, and lowered plasma tryptophan, which is associated with indices of immune activation and glucocorticoid hypersecretion. Lowered tryptophan and increased TRYCATs induce T cell unresponsiveness and therefore may exert a negative feedback on the primary inflammatory response in depression. It is concluded that activation of the TRYCAT pathway by IDO and TDO may be associated with the development of depressive symptoms through tryptophan depletion and the detrimental effects of TRYCATs. Therefore, the TRYCAT pathway should be a new drug target in depression. Direct inhibitors of IDO are less likely to be useful drugs than agents, such as kynurenine hydroxylase inhibitors; drugs which block the primary immune response; compounds that increase the protective effects of kynurenic acid; and specific antioxidants that target IDO activation, the immune and oxidative pathways, and 5-HT as well.

The inflammatory & neurodegenerative (I&ND) hypothesis of depression: leads for future research and new drug developments in depression

Despite extensive research, the current theories on serotonergic dysfunctions and cortisol hypersecretion do not provide sufficient explanations for the nature of depression. Rational treatments aimed at causal factors of depression are not available yet. With the currently available antidepressant drugs, which mainly target serotonin, less than two thirds of depressed patients achieve remission. There is now evidence that inflammatory and neurodegenerative (I&ND) processes play an important role in depression and that enhanced neurodegeneration in depression may-at least partly-be caused by inflammatory processes. Multiple inflammatory-cytokines, oxygen radical damage, tryptophan catabolites-and neurodegenerative biomarkers have been established in patients with depression and these findings are corroborated by animal models of depression. A number of vulnerability factors may predispose towards depression by enhancing inflammatory reactions, e.g. lower peptidase activities (dipeptidyl-peptidase IV, DPP IV), lower omega-3 polyunsaturated levels and an increased gut permeability (leaky gut). The cytokine hypothesis considers that external, e.g. psychosocial stressors, and internal stressors, e.g. organic inflammatory disorders or conditions, such as the postpartum period, may trigger depression via inflammatory processes. Most if not all antidepressants have specific anti-inflammatory effects, while restoration of decreased neurogenesis, which may be induced by inflammatory processes, may be related to the therapeutic efficacy of antidepressant treatments. Future research to disentangle the complex etiology of depression calls for a powerful paradigm shift, i.e. by means of a high throughput-high quality screening, including functional genetics and genotyping microarrays; established and novel animal and ex vivo-in vitro models for depression, such as new transgenic mouse models and endophenotype-based animal models, specific cell lines, in vivo and ex vivo electroporation, and organotypic brain slice culture models. This screening will allow to: 1) discover new I&ND biomarkers, both at the level of gene expression and the phenotype; and elucidate the underlying molecular I&ND pathways causing depression; and 2) identify new therapeutic targets in the I&ND pathways; develop new anti-I&ND drugs for these targets; select existing anti-I&ND drugs or substances that could augment the efficacy of antidepressants; and predict therapeutic response by genetic I&ND profiles.

Microgravity and the implications for wound healing

Wound healing is a sophisticated response ubiquitous to various traumatic stimuli leading to an anatomical/functional disruption. The aim of present article was to review the current evidence regarding the effects of microgravity on wound healing dynamics. Modulation of haemostatic phase because of alteration of platelet quantity and function seems probable. Furthermore, production of growth factors that are released from activated platelets and infiltration/function of inflammatory cells seem to be impaired by microgravity. Proliferation of damaged structures is dependent on orchestrated function of various growth factors, for example transforming growth factors, platelet-derived growth factor and epidermal growth factor, all of which are affected by microgravitational status. Moreover, gravity-induced alterations of gap junction, neural inputs, and cell populations have been reported. It may be concluded that different cellular and extracellular element involved in the healing response are modified through effect of microgravity which may lead to impairment in healing dynamics.

The immunophilin ligands cyclosporin A and FK506 suppress prostate cancer cell growth by androgen receptor-dependent and -independent mechanisms

The androgen receptor (AR) contributes to growth of prostate cancer even under conditions of androgen ablation. Thus, new strategies to target AR activity are needed. The AR interacts with the immunophilin FK506-binding protein 52 (FKBP52), and studies in the FKBP52 knockout mouse have shown that this protein is essential to AR activity in the prostate. Therefore, we tested whether the immunophilin ligand FK506 affected AR activity in prostate cancer cell lines. We also tested the hypothesis that the AR interacts with another immunophilin, cyclophilin 40 (Cyp40), and is regulated by its cognate ligand cyclosporin A (CsA). We show that levels of FKBP52, FKBP51, Cyp40, and a related co-chaperone PP5 were much higher in prostate cancer cells lines [(LNCaP), PC-3, and DU145] compared with primary prostate cells, and that the AR of LNCaP cells can interact with Cyp40. In the absence of androgen, CsA caused inhibition of cell growth in the AR-positive LNCaP and AR-negative PC-3 and DU145 cell lines. Interestingly, FK506 only inhibited LNCaP cells, suggesting a dependence on the AR for this effect. Both CsA and FK506 inhibited growth without inducing apoptosis. In LNCaP cells, CsA completely blocked androgen-stimulated growth, whereas FK506 was partially effective. Further studies in LNCaP cells revealed that CsA and FK506 were able to block or attenuate several stages of AR signaling, including hormone binding, nuclear translocation, and activity at several AR-responsive reporter and endogenous genes. These findings provide the first evidence that CsA and FK506 can negatively modulate proliferation of prostate cells in vitro. Immunophilins may now serve as new targets to disrupt AR-mediated prostate cancer growth.

Glucocorticoids activate TGF-beta induced PAI-1 and CTGF expression in rat hepatocytes

Background

In addition to the activation of hepatic stellate cells TGF-β govern apoptosis and growth control of hepatocytes in liver injury. In non-parenchymal cells, TGF-β induces plasminogen activator inhibitor 1 (PAI-1) and connective tissue growth factor (CTGF) expression, which are involved in extra cellular matrix formation. Both genes were also regulated by glucocorticoids, which in certain cases showed antagonistic effects to the TGF-β-Smad 3 pathway. The purpose of our work was to investigate the influence of TGF-β and dexamethasone on PAI-1 and CTGF expression and secretion in primary hepatocytes.

Results

By examining PAI-1 and CTGF mRNA and protein expression in cell lysates and cell-conditioned media under the influence of TGF-β and dexamethasone, we analysed signalling pathways controlling their expression. TGF-β and dexamethasone significantly co-induce PAI-1 and CTGF protein expression. On the other hand, we showed that TGF-β diminished a glucocorticoid receptor dependent luciferase reporter signal in Hep-G2. Inhibition of Erk downstream activation decreased TGF-β induced CTGF and PAI-1 expression to a basal level. PAI-1 was directly secreted by hepatocytes, whereas secretion of CTGF was retarded.

Conclusion

The data provide evidence that beside the TGF-β-Smad 3 pathway CTGF and PAI-1 expression is additionally dependent on Erk activity in hepatocytes giving new insights into regulation of the profibrogenic proteins.

Low glucocorticoid receptor (GR), high Dig2 and low Bcl-2 expression in double positive thymocytes of BALB/c mice indicates their endogenous glucocorticoid hormone exposure

Several studies have shown that of the four major thymocyte subsets, the CD4/CD8 double positive (DP) thymocytes are the most sensitive to in vivo glucocorticoid hormone (GC)-induced apoptosis. Our aim was to analyse fine molecular differences among thymocyte subgroups that could underlie this phenomenon. Therefore, we characterised the glucocorticoid hormone receptor (GR) expression of thymocyte subgroups both at the mRNA and protein levels by real-time PCR and flow cytometry, and correlated these features to their apoptotic sensitivity. We also investigated the time-dependent effects of the GC agonist dexamethasone (DX) with or without GC antagonist (RU486) treatments on GR mRNA/protein expression. We also analysed the expression of two apoptosis-related gene products: dexamethasone-induced gene 2 (Dig2) mRNA and Bcl-2 protein. We found that DN thymocytes had the highest GR expression, followed by CD8 single positive (SP), CD4 SP and DP thymocytes in 4-week-old BALB/c mice, both at the mRNA and protein levels, respectively. In DP cells, the Dig2 expression was significantly higher, while the Bcl-2 expression was significantly lower than in DN, CD4 SP and CD8 SP thymocytes. Single high dose DX treatment caused time-dependent depletion of DP thymocytes due to their higher apoptosis rate, which could not be abolished with RU486 pretreatment. After a single high dose DX treatment, there was a transient, significant increase of the GR mRNA and protein level of unsorted thymocytes after 8 and 16 h, followed by a significant decrease at 24 h, respectively. The time-dependent GR expression changes after DX administration could not be inhibited by the GC antagonist RU486. Twenty-four hours after exposure to high dose DX the DN, CD4 SP and CD8 SP cells showed a significant decrease of GR mRNA and protein expression, whereas the DP thymocytes, showed no significant alteration of GR mRNA or protein expression. The kinetical analysis of GR expression and apoptotic marker changes upon single high dose GC analogue administration revealed a two-phase process in thymocytes: early events, within 4-8 h, include GR upregulation and early apoptosis induction, while the late events appear most prominently at 16-20 h, when the GR is already downregulated and apoptotic cell ratio reaches its peak, with marked DP cell depletion. The low GR, high Dig2 and low Bcl-2 expression, coupled with the absence of homologous downregulation of GR after exogenous GC analogue treatment, could contribute to the high GC sensitivity of DP thymocytes. The downregulated GR and Bcl-2 together with the upregulated Dig2 level in DP cells indicates the significance of intrathymic GC effects at this differentiation stage. Since GR expression changes and apoptotic events could not be completely inhibited by GC antagonist, we propose the involvement of non-genomic GR mechanisms in these processes.

Chromatin-dependent E1A activity modulates NF-kappaB RelA-mediated repression of glucocorticoid receptor-dependent transcription

The role of chromatin-dependent regulatory mechanisms in the repression of glucocorticoid-dependent transcription from the murine mammary tumor virus (MMTV) promoter by p65 and E1A was investigated by using chromatin and transiently transfected reporters. The p65 RelA subunit of NF-kappaB represses MMTV expression on either transient or integrated reporters. In contrast, the viral oncoprotein E1A represses a transient but not an integrated MMTV. E1A repression is attenuated by chromatin, suggesting p65 but not E1A manipulates chromatin appropriately to inhibit the GR. Coexpression of p65 and E1A additively represses the transient MMTV but restores the transcriptional activation of the chromatin MMTV in response to glucocorticoids. This indicates that E1A has a dominant chromatin-dependent activity that attenuates repression by p65. E1A, p65, and GR bind the MMTV promoter, and chromatin remodeling enhances binding on both repressed and activated promoters. In addition, p65 requires Brg for repression of the integrated MMTV. This suggests that neither p65 repression nor E1A attenuation of repression results from an inhibition of remodeling that prevents transcription factor binding. Furthermore, p300/CBP is also required for both repression and attenuation by p65 and E1A. E1A and p65 mutants that do not bind p300/CBP are inactive, indicative of a requirement for p300/CBP-dependent complex formation for both repression and attenuation with chromatin. These data suggest that both the p65-dependent repression and the E1A-mediated attenuation of repression require the Brg1-dependent chromatin remodeling function and p300/CBP-dependent complex formation at a promoter assembled within chromatin.