Glucocorticoids Regulate Tristetraprolin Synthesis and Posttranscriptionally Regulate Tumor Necrosis Factor Alpha Inflammatory Signaling (original) (raw)
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Endocrinology, 2012
Synthetic glucocorticoids are widely used for treatment of many inflammatory diseases. However, long-term glucocorticoid treatment can cause a variety of negative side effects. A genome-wide microarray analysis was performed in human lung A549 cells to identify genes regulated by both the antiinflammatory steroid dexamethasone (Dex) and the proinflammatory cytokine TNF␣. Unexpectedly, we discovered that numerous genes were coregulated by treatment with both Dex and TNF␣. We evaluated the mechanism of coregulation of one of these genes, serpinA3 (␣-1 antichymotrypsin), a secreted, acute phase protein strongly associated with numerous inflammatory diseases. Up-regulation of serpinA3 requires the presence of both the glucocorticoid receptor and TNF␣ soluble receptor 1. Treatment with Dex or TNF␣ resulted in a 10-to 25-fold increase of serpinA3 mRNA, whereas coadministration of Dex and TNF␣ led to a synergistic increase in serpinA3 mRNA. The naturally occurring glucocorticoid, cortisol, also resulted in a synergistic increase in serpinA3 mRNA levels in A549 cells. Furthermore, in vivo treatment of C57BL/6 mice with Dex and TNF␣ resulted in coregulation of serpinA3 mRNA levels in both lung and liver tissues. Finally, chromatin immunoprecipitation analyses suggest that glucocorticoid receptor binding to the serpinA3 transcriptional start site can be enhanced by the combination of Dex plus TNF␣ treatment of A549 cells. These studies demonstrate that glucocorticoids and proinflammatory compounds can coregulate genes associated with human disease. This discovery may underlie the basis of some of the adverse effects associated with long-term glucocorticoid therapy.
Journal of Clinical Investigation, 1996
Cytokine-induced glucocorticoid secretion and glucocorticoid inhibition of cytokine synthesis and pleiotropic actions act as important safeguards in preventing cytokine overreaction. We found that TNF-␣ increased glucocorticoid-induced transcriptional activity of the glucocorticoid receptor (GR) via the glucocorticoid response elements (GRE) in L-929 mouse fibroblasts transfected with a glucocorticoid-inducible reporter plasmid. In addition, TNF-␣ also enhanced GR number. The TNF-␣ effect on transcriptional activity was absent in other cell lines that express TNF-␣ receptors but not GRs, and became manifest when a GR expression vector was cotransfected, indicating that TNF-␣ , independent of any effect it may have on GR number, has a stimulatory effect on the glucocorticoid-induced transcriptional activity of the GR. Moreover, TNF-␣ increased GR binding to GRE. As a functional biological correlate of this mechanism, priming of L-929 cells with a low (noncytotoxic) dose of TNF-␣ significantly increased the sensitivity to glucocorticoid inhibition of TNF-␣-induced cytotoxicity/apoptosis. TNF-␣ and IL-1  had the same stimulatory action on glucocorticoid-induced transcriptional activity of the GR via the GRE, in different types of cytokine/glucocorticoid target cells (glioma, pituitary, epithelioid). The phenomenon may therefore reflect a general molecular mechanism whereby cytokines modulate the transcriptional activity of the GR, thus potentiating the counterregulation by glucocorticoids at the level of their target cells.
PloS one, 2013
Binding of glucocorticoid to the glucocorticoid receptor (GR/NR3C1) may repress inflammatory gene transcription via direct, protein synthesis-independent processes (transrepression), or by activating transcription (transactivation) of multiple antiinflammatory/repressive factors. Using human pulmonary A549 cells, we showed that 34 out of 39 IL-1b-inducible mRNAs were repressed to varying degrees by the synthetic glucocorticoid, dexamethasone. Whilst these repressive effects were GRdependent, they did not correlate with either the magnitude of IL-1b-inducibility or the NF-kB-dependence of the inflammatory genes. This suggests that induction by IL-1b and repression by dexamethasone are independent events. Roles for transactivation were investigated using the protein synthesis inhibitor, cycloheximide. However, cycloheximide reduced the IL-1b-dependent expression of 13 mRNAs, which, along with the 5 not showing repression by dexamethasone, were not analysed further. Of the remaining 21 inflammatory mRNAs, cycloheximide significantly attenuated the dexamethasonedependent repression of 11 mRNAs that also showed a marked time-dependence to their repression. Such effects are consistent with repression occurring via the de novo synthesis of a new product, or products, which subsequently cause repression (i.e., repression via a transactivation mechanism). Conversely, 10 mRNAs showed completely cycloheximideindependent, and time-independent, repression by dexamethasone. This is consistent with direct GR transrepression. Importantly, the inflammatory mRNAs showing attenuated repression by dexamethasone in the presence of cycloheximide also showed a significantly greater extent of repression and a higher potency to dexamethasone compared to those mRNAs showing cycloheximide-independent repression. This suggests that the repression of inflammatory mRNAs by GR transactivation-dependent mechanisms accounts for the greatest levels of repression and the most potent repression by dexamethasone. In conclusion, our data indicate roles for both transrepression and transactivation in the glucocorticoiddependent repression of inflammatory gene expression. However, transactivation appears to account for the more potent and efficacious mechanism of repression by glucocorticoids on these IL-1b-induced genes.
The Journal of biological chemistry, 2015
Tumor necrosis factor α (TNF) is central to inflammation and may play a role in the pathogenesis of asthma. The 3'-untranslated region of the TNF transcript contains AU-rich elements (AREs) that are targeted by the RNA-binding protein, tristetraprolin (ZFP36), which is itself up-regulated by inflammatory stimuli, to promote mRNA degradation. Using primary human bronchial epithelial (HBE) and pulmonary epithelial A549 cells, we confirm that interleukin-1β (IL1B) induces expression of dual-specificity phosphatase 1 (DUSP1), ZFP36 and TNF. While IL1B-induced DUSP1 is involved in feedback control of MAPK pathways, ZFP36 exerts negative (incoherent) feed-forward control of TNF mRNA and protein expression. DUSP1 silencing increased IL1B-induced ZFP36 expression at 2h and profoundly repressed TNF mRNA at 6h. This was partly due to increased TNF mRNA degradation, an effect that was reduced by ZFP36 silencing. This confirms a regulatory network, whereby DUSP1-dependent negative feedback ...
Role of RNA-binding protein tristetraprolin in tumor necrosis factor-α mediated gene expression
Biochemical and Biophysical Research Communications, 2012
Glucocorticoids (GCs) are the mainstay of anti-inflammatory therapy. Modulation of posttranscriptional regulation (PTR) of gene expression by GCs is a relevant yet poorly characterized mechanism of their action. The RNA-binding protein tristetraprolin (TTP) plays a central role in PTR by binding to AU-rich elements in the 3-untranslated region of proinflammatory transcripts and accelerating their decay. We found that GCs induce TTP expression in primary and immortalized human bronchial epithelial cells. To investigate the importance of PTR and the role of TTP in GC function, we compared the effect of GC treatment on genome-wide gene expression using mouse embryonic fibroblasts (MEFs) obtained from wild-type and TTP ؊/؊ mice. We confirmed that GCs induce TTP in MEFs and observed in TTP ؊/؊ MEFs a striking loss of up to 85% of GC-mediated gene expression. Gene regulation by TNF-␣ was similarly affected, as was the antagonistic effect of GC on TNF-␣-induced response. Inflammatory genes, including cytokines and chemokines, were among the genes whose sensitivity to GCs was affected by lack of TTP. Silencing of TTP in WT MEFs by small interfering RNA confirmed loss of GC response in selected targets. Immunoprecipitation of ribonucleoprotein complexes revealed binding of TTP to several validated transcripts. Changes in the rate of transcript degradation studied by actinomycin D were documented for only a subset of transcripts bound to TTP. These results reveal a strong and previously unrecognized contribution of PTR to the anti-inflammatory action of GCs and point at TTP as a key factor mediating this process through a complex mechanism of action.
Gene profiling reveals unknown enhancing and suppressive actions of glucocorticoids on immune cells
The FASEB Journal, 2002
Glucocorticoids continue to be the major immunomodulatory agents used in clinical medicine today. However, their actions as anti-inflammatory and immunosuppressive drugs are both beneficial and deleterious. We analyzed the effect of glucocorticoids on the gene expression profile of peripheral blood mononuclear cells from healthy donors. DNA microarray analysis combined with quantitative TaqMan PCR and flow cytometry revealed that glucocorticoids induced the expression of chemokine, cytokine, and complement family members as well as of newly discovered innate immune-related genes, including scavenger and Toll-like receptors. In contrast, glucocorticoids repressed the expression of adaptive immune-related genes. Simultaneous inhibitory and stimulatory effects of glucocorticoids were found on inflammatory T helper subsets and apoptosis-related gene clusters. In cells activated by T cell receptor cross-linking, glucocorticoids down-regulated the expression of specific genes that were previously up-regulated in resting cells, suggesting a potential new mechanism by which they exert positive and negative effects. Considering the broad and continuously renewed interest in glucocorticoid therapy, the profiles we describe here will be useful in designing more specific and efficient treatment strategies. G., Boettner, A., Ehrhart-Bornstein, M., O'Shea, J. J., Chrousos, G. P., Bornstein, S. R. Gene profiling reveals unknown enhancing and suppressive actions of glucocorticoids on immune cells. FASEB J. 16, 61-71 (2002) 61 0892-6638/02/0016-0061 © FASEB a S: sense primer; AS: antisense primer; TM: TaqMan probe; Primer size: Base pairs; TLR4: Toll-like receptor 4; MARCO: macrophage receptor with collagenouse structure; THBS1: thrombospondin 1; STAT1: signal transducer and activator of transcription 1; IRF4: interferon regulatory factor 4; PAI2: plasminogen activator inhibitor type2; CD127: interleukin 7 receptor; IL10: interleukin 10; CCR2: chemokine receptor 2.
Glucocorticoids and Inflammation Revisited: The State of the Art
Neuroimmunomodulation, 2002
Glucocorticoids have been used in the treatment of inflammatory and autoimmune diseases and to prevent graft rejection for over 50 years. These hormones exert their effects through cytoplasmic, heat shock proteinbound glucocorticoid receptors that translocate into the nucleus, where they regulate the transcriptional activity of responsive genes by binding to specific promoter DNA sequences (transactivation) or by interacting with transcription factors (transrepression). By interacting with different signaling pathways, newly characterized nuclear receptor coregulators enhance or diminish the actions of glucocorticoids, thus explaining the gene-, cell-, tissue-and context-dependent actions of glucocorticoids. Glucocorticoids modulate genes involved in the priming of the innate immune response, while their actions on the adaptive immune response are to suppress cellular [T helper (Th)1-directed] immunity and promote humoral (Th2-directed) immunity and tolerance. The past decade has produced new insights into the mechanisms of glucocorticoid sensitivity and resistance of inflammatory, autoimmune and allergic diseases. Both the quality and severity of the inflammatory stimulus, as well as the genetics and constitution of the patient, play key roles in the glucocorticoid sensitivity, dependency and resistance of these diseases. Although glucocorticoids increase susceptibility to opportunistic infections, they are also highly beneficial in the presence of serious systemic inflammation, such as that observed in septic shock and acute respiratory distress syndrome, when administered in a sustained fashion throughout the course of the disease. Glucocorticoids produce their cardiovascular, metabolic and antigrowth side effects through molecular mechanisms distinct from those involved in immunomodulation. Fortunately, the first generation of tissue-and immune-versus cardiovascular/ metabolic effect-selective glucocorticoids is available for study and further improvement. 'Designer' glucocorticoids promise to be a great new advance in the therapy of inflammatory diseases.
Clinical & Experimental Immunology, 2007
Summary There is accumulating evidence that the transrepressional effect of glucocorticoids in down-regulating proinflammatory gene expression might be regulated by an action on histone acetylation. To investigate this, we studied the effect of two glucocorticoids (dexamethasone and triamcinolone acetonide) on reducing lipopolysaccharide (LPS)- and tumour necrosis factor (TNF)-α-induced interleukin (IL)-8 release in a monocytic cell line and two lymphocytic cell lines (HUT-78 and Jurkat). The effect of the histone deacetylase inhibitor trichostatin A (TSA) on LPS- and TNF-α-induced IL-8 release and its repression by glucocorticoids was also examined. LPS and TNF-α induced IL-8 release in all three cell lines and this induction was inhibited by both dexamethasone and triamcinolone. Pretreatment of cells with TSA enhanced basal and LPS- and TNFα-stimulated IL-8 release in all three cell lines. TSA also attenuated the inhibitory effect of glucocorticoids on stimulated IL-8 release. Chr...
Proceedings of the National Academy of Sciences, 2019
Glucocorticoid resistance (GCR) is defined as an unresponsiveness to the therapeutic effects, including the antiinflammatory ones of glucocorticoids (GCs) and their receptor, the glucocorticoid receptor (GR). It is a problem in the management of inflammatory diseases and can be congenital as well as acquired. The strong proinflammatory cytokine TNF-alpha (TNF) induces an acute form of GCR, not only in mice, but also in several cell lines: e.g., in the hepatoma cell line BWTG3, as evidenced by impaired Dexamethasone (Dex)-stimulated direct GR-dependent gene up- and down-regulation. We report that TNF has a significant and broad impact on this transcriptional performance of GR, but no impact on nuclear translocation, dimerization, or DNA binding capacity of GR. Proteome-wide proximity-mapping (BioID), however, revealed that the GR interactome was strongly modulated by TNF. One GR cofactor that interacted significantly less with the receptor under GCR conditions is p300. NFκB activatio...