scholarly journals Bromodomain containing 9 (BRD9) regulates macrophage inflammatory responses by potentiating glucocorticoid receptor activity

2021 ◽  
Vol 118 (35) ◽  
pp. e2109517118
Author(s):  
Liu Wang ◽  
Tae Gyu Oh ◽  
Jason Magida ◽  
Gabriela Estepa ◽  
S. M. Bukola Obayomi ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Inflammatory Responses ◽  
Chromatin Accessibility ◽  
Antiinflammatory Drugs ◽  
Transcriptional Responses ◽  
Sequence Of Events ◽  
Inflammatory Stimuli ◽  
Genetic Deletion ◽  
Adipose Inflammation ◽  
Pharmacologic Inhibition

In macrophages, homeostatic and immune signals induce distinct sets of transcriptional responses, defining cellular identity and functional states. The activity of lineage-specific and signal-induced transcription factors are regulated by chromatin accessibility and other epigenetic modulators. Glucocorticoids are potent antiinflammatory drugs; however, the mechanisms by which they selectively attenuate inflammatory genes are not yet understood. Acting through the glucocorticoid receptor (GR), glucocorticoids directly repress inflammatory responses at transcriptional and epigenetic levels in macrophages. A major unanswered question relates to the sequence of events that result in the formation of repressive regions. In this study, we identify bromodomain containing 9 (BRD9), a component of SWI/SNF chromatin remodeling complex, as a modulator of glucocorticoid responses in macrophages. Inhibition, degradation, or genetic depletion of BRD9 in bone marrow-derived macrophages significantly attenuated their responses to both liposaccharides and interferon inflammatory stimuli. Notably, BRD9-regulated genes extensively overlap with those regulated by the synthetic glucocorticoid dexamethasone. Pharmacologic inhibition of BRD9 potentiated the antiinflammatory responses of dexamethasone, while the genetic deletion of BRD9 in macrophages reduced high-fat diet-induced adipose inflammation. Mechanistically, BRD9 colocalized at a subset of GR genomic binding sites, and depletion of BRD9 enhanced GR occupancy primarily at inflammatory-related genes to potentiate GR-induced repression. Collectively, these findings establish BRD9 as a genomic antagonist of GR at inflammatory-related genes in macrophages, and reveal a potential for BRD9 inhibitors to increase the therapeutic efficacies of glucocorticoids.

scholarly journals Glucocorticoid receptor activation induces gene-specific transcriptional memory and universally reversible changes in chromatin accessibility

2021 ◽  
Author(s):  
Melissa Bothe ◽  
René Buschow ◽  
Sebastiaan H. Meijsing
Keyword(s):  
Glucocorticoid Receptor ◽  
Transcriptional Repression ◽  
Single Gene ◽  
Transcriptional Response ◽  
Receptor Activation ◽  
Chromatin Accessibility ◽  
Airway Epithelial Cells ◽  
Transcriptional Responses ◽  
Transcriptional Memory ◽  
Induced Changes

AbstractGlucocorticoids are stress hormones that elicit cellular responses by binding to the glucocorticoid receptor (GR), a ligand-activated transcription factor. The exposure of cells to this hormone induces wide-spread changes in the chromatin landscape and gene expression. Previous studies have suggested that some of these changes are reversible whereas others persist even when the hormone is no longer around. However, when we examined chromatin accessibility in human airway epithelial cells after hormone washout, we found that the hormone-induced changes were universally reversed after one day. Reversibility of hormone-induced changes are found for GR-occupied opening sites and also for closing sites that typically lack GR occupancy. These closing sites are enriched near repressed genes, suggesting that transcriptional repression by GR does not require nearby GR binding. Mirroring what we say in terms of chromatin accessibility, we found that transcriptional responses to hormone are universally reversable. Moreover, priming of cells by a previous exposure to hormone, in general, did not alter the transcriptional response to a subsequent encounter of the same cue. Interestingly, despite the short-lived nature of hormone-induced changes in the chromatin landscape, we identified a single gene, ZBTB16, that displays transcriptional memory manifesting itself as a more robust transcriptional response upon repeated hormone stimulation. Single-cell analysis revealed that the more robust response is driven by a higher probability of primed cells to activate ZBTB16 and by a subset of cells that express the gene at levels that are higher than the induction levels observed for naïve cells. Although our study shows that hormone-induced changes are typically reversable, exposure to hormone can induce gene-specific changes in the response to subsequent exposures which may play a role in habituation to stressors and changes in glucocorticoid sensitivity.

scholarly journals Differential Activity and Utilization of Glucocorticoid Receptor Binding Sites Yields Transcriptional Heterogeneity

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A499-A500
Author(s):  
Jackson Andrew Hoffman ◽  
Kevin W Trotter ◽  
Christopher R Day ◽  
James M Ward ◽  
Joseph Rodriguez ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Histone Acetylation ◽  
Single Molecule ◽  
Binding Sites ◽  
Transcriptional Response ◽  
Chromatin Accessibility ◽  
Human Diseases ◽  
Cellular Heterogeneity ◽  
Patient Specific ◽  
Transcriptional Responses

Abstract Synthetic glucocorticoids such as Dexamethasone (Dex) are widely prescribed drugs used to treat a variety of human diseases including auto-immune disorders, asthma, cancer, and COVID-19. The transcriptional response to glucocorticoids is elicited by the Glucocorticoid Receptor (GR), which enters the nucleus upon Dex treatment and interacts with thousands of enhancer elements throughout the genome. We recently demonstrated that the Dex response in human breast cancer cells is highly heterogeneous and that individual cells have unique transcriptional responses to Dex. To examine whether this heterogeneity arises from differential utilization of distinct GR-bound enhancers, we focused on the Dex response at the DNA Damage Inducible Transcript 4 (DDIT4) gene. Using a variety of genomic techniques, we identified four GR binding sites (GBSs) 18-30kb upstream of the DDIT4 TSS with differential patterns of chromatin accessibility, histone acetylation, SWI/SNF recruitment, and enhancer RNA (eRNA) transcription. To determine whether these GBSs had unique requirements for DDIT4 transcription, we used CRISPR-CAS9 to generate homozygous deletions of each site. Using ChIP-seq, 4C-seq, single molecule fluorescent in situ hybridization (smFISH), and RT-PCR, we demonstrated GR binding to these GBSs was independent and each GBS deletion had unique effects on DDIT4 and eRNA transcription, local histone acetylation, and chromatin looping. Deletion of any of the first three GBSs resulted in delayed and/or decreased induction of DDIT4 transcription whereas deletion of the fourth GBS resulted in significant upregulation of both DDIT4 and eRNA transcription. Thus, three of the GBSs acted as enhancers of DDIT4 expression while the fourth functioned as a suppressor. Strikingly, smFISH also revealed that these enhancers contributed to cellular heterogeneity, as deleting the GBSs altered the frequency and amplitude of DDIT4 transcription across cell populations. Taken together, these results demonstrate that individual GBSs uniquely contribute to cell-to-cell heterogeneity within the transcriptional response of DDIT4 to Dex. Furthermore, they underscore the possibility that targeted modification of individual GBSs could be utilized to tailor custom, patient-specific strategies for the treatment of human diseases.

scholarly journals Assessing the regulatory potential of transposable elements using chromatin accessibility profiles of maize transposons

Genetics ◽  
2020 ◽  
Vol 217 (1) ◽  
Author(s):  
Jaclyn M Noshay ◽  
Alexandre P Marand ◽  
Sarah N Anderson ◽  
Peng Zhou ◽  
Maria Katherine Mejia Guerra ◽  
...  
Keyword(s):  
Transposable Elements ◽  
Allelic Variation ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Transcriptional Responses ◽  
Maize Genotypes ◽  
Show Evidence ◽  
Regulatory Potential ◽  
Dna Regulatory Elements ◽  
Accessible Chromatin

Abstract Transposable elements (TEs) have the potential to create regulatory variation both through the disruption of existing DNA regulatory elements and through the creation of novel DNA regulatory elements. In a species with a large genome, such as maize, many TEs interspersed with genes create opportunities for significant allelic variation due to TE presence/absence polymorphisms among individuals. We used information on putative regulatory elements in combination with knowledge about TE polymorphisms in maize to identify TE insertions that interrupt existing accessible chromatin regions (ACRs) in B73 as well as examples of polymorphic TEs that contain ACRs among four inbred lines of maize including B73, Mo17, W22, and PH207. The TE insertions in three other assembled maize genomes (Mo17, W22, or PH207) that interrupt ACRs that are present in the B73 genome can trigger changes to the chromatin, suggesting the potential for both genetic and epigenetic influences of these insertions. Nearly 20% of the ACRs located over 2 kb from the nearest gene are located within an annotated TE. These are regions of unmethylated DNA that show evidence for functional importance similar to ACRs that are not present within TEs. Using a large panel of maize genotypes, we tested if there is an association between the presence of TE insertions that interrupt, or carry, an ACR and the expression of nearby genes. While most TE polymorphisms are not associated with expression for nearby genes, the TEs that carry ACRs exhibit enrichment for being associated with higher expression of nearby genes, suggesting that these TEs may contribute novel regulatory elements. These analyses highlight the potential for a subset of TEs to rewire transcriptional responses in eukaryotic genomes.

scholarly journals The dynamic pattern of glucocorticoid receptor-mediated transcriptional responses in neuronal PC12 cells

2006 ◽  
Vol 99 (4) ◽  
pp. 1282-1298 ◽  
Author(s):  
M. C. Morsink ◽  
M. Joëls ◽  
R. A. Sarabdjitsingh ◽  
O. C. Meijer ◽  
E. R. De Kloet ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Pc12 Cells ◽  
Transcriptional Responses ◽  
Dynamic Pattern ◽  
Neuronal Pc12 Cells

scholarly journals Chromatin accessibility pre-determines glucocorticoid receptor binding patterns

2011 ◽  
Vol 43 (3) ◽  
pp. 264-268 ◽  
Author(s):  
Sam John ◽  
Peter J Sabo ◽  
Robert E Thurman ◽  
Myong-Hee Sung ◽  
Simon C Biddie ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Receptor Binding ◽  
Chromatin Accessibility

scholarly journals Sexually Dimorphic Relationships Among Saa3 (Serum Amyloid A3) Inflammation, and Cholesterol Metabolism Modulate Atherosclerosis in Mice

2021 ◽  
Author(s):  
Alan Chait ◽  
Shari Wang ◽  
Leela Goodspeed ◽  
Diego Gomes ◽  
Katherine E. Turk ◽  
...  
Keyword(s):  
Plasma Lipids ◽  
Cholesterol Metabolism ◽  
Saturated Fat ◽  
Serum Amyloid ◽  
Male And Female ◽  
Female Mice ◽  
Inflammatory Stimuli ◽  
Elevated Cholesterol ◽  
Hybrid Mouse Diversity Panel ◽  
Adipose Inflammation

Objective: Expression of the extrahepatic acute-phase protein Saa3 (serum amyloid A3) increases in response to acute and chronic inflammatory stimuli and is elevated in adipose tissue and macrophages in obese mice. A recent report suggested that Saa3 is proatherogenic in male ApoE −/− mice. Because of our previous observation that female but not male Saa3-deficient mice are protected from obesity, adipose inflammation, and hyperlipidemia, we sought to determine whether Saa3 differentially modulates atherosclerosis in mice of both sexes. Approach and Results: To promote atherosclerosis, Saa3 +/+ and Saa3 −/− male and female mice were crossed with Ldlr −/− mice. All mice consumed a diet high in saturated fat and sucrose with 0.15% added cholesterol for 16 weeks. Plasma lipids and atherosclerosis levels were assessed. Female Saa3 −/− Ldlr − /− mice exhibited elevated cholesterol levels relative to Saa3 +/+ Ldlr −/− controls and exhibited increased atherosclerosis, while male Saa3 −/− Ldlr −/− mice were protected from atherosclerosis. Data from the hybrid mouse diversity panel revealed that Saa3 associates strongly with inflammatory, Trem2-associated, and tissue remodeling genes and pathways in males but not females, an effect confirmed in liver tissue, atherosclerotic lesions, and cultured macrophages. Macrophages isolated from male and female mice showed differential inflammatory effects of Saa3 deficiency, an effect linked with sex steroid signaling. Cholesterol efflux capacity was increased in Saa3 −/− males only. Conclusions: Saa3 is proatherogenic in male but atheroprotective in female mice, effects that may be related to sex-specific relationships between Saa3, cholesterol metabolism, inflammatory genes, and Trem2 macrophages.

scholarly journals Selective induction of endothelial P2Y6 nucleotide receptor promotes vascular inflammation

Blood ◽  
2011 ◽  
Vol 117 (8) ◽  
pp. 2548-2555 ◽  
Author(s):  
Ann-Kathrin Riegel ◽  
Marion Faigle ◽  
Stephanie Zug ◽  
Peter Rosenberger ◽  
Bernard Robaye ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Vascular Inflammation ◽  
In Vivo Studies ◽  
Nucleotide Receptors ◽  
Transcriptional Responses ◽  
Lps Challenge ◽  
Screening Experiments ◽  
P2y6 Receptor

Abstract During a systemic inflammatory response endothelial-expressed surface molecules have been strongly implicated in orchestrating immune responses. Previous studies have shown enhanced extracellular nucleotide release during acute inflammatory conditions. Therefore, we hypothesized that endothelial nucleotide receptors could play a role in vascular inflammation. To address this hypothesis, we performed screening experiments and exposed human microvascular endothelia to inflammatory stimuli, followed by measurements of P2Y or P2X transcriptional responses. These studies showed a selective induction of the P2Y6 receptor (> 4-fold at 24 hours). Moreover, studies that used real-time reverse transcription–polymerase chain reaction, Western blot analysis, or immunofluorescence confirmed time- and dose-dependent induction of P2Y6 with tumor necrosis factor α or Lipopolysaccharide (LPS) stimulation in vitro and in vivo. Studies that used MRS 2578 as P2Y6 receptor antagonist showed attenuated nuclear factor κB reporter activity and proinflammatory gene expression in human microvascular endothelial cells in vitro. Moreover, pharmacologic or genetic in vivo studies showed attenuated inflammatory responses in P2Y6−/− mice or after P2Y6 antagonist treatment during LPS-induced vascular inflammation. These studies show an important contribution of P2Y6 signaling in enhancing vascular inflammation during systemic LPS challenge and implicate the P2Y6 receptor as a therapeutic target during systemic inflammatory responses.

Abstract 087: Mitochondrial Fission Inducer, Dynamin-Related Protein 1 (DRP1), is Required for Endothelial Inflammatory Responses

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Steven J Forrester ◽  
Tatsuo Kawai ◽  
Katherine J Elliott ◽  
Kunie Eguchi ◽  
Victor Rizzo ◽  
...  
Keyword(s):  
Er Stress ◽  
Inflammatory Responses ◽  
Vascular Dysfunction ◽  
Mitochondrial Fission ◽  
Critical Role ◽  
Dominant Negative ◽  
Low Grade ◽  
Aortic Endothelial Cells ◽  
Endothelial Inflammation ◽  
Inflammatory Stimuli

Among various cardiovascular diseases, hypertension (HTN) is considered to be a disease plagued by chronic low-grade inflammation associated with endothelial dysfunction. Interestingly, recent studies have identified mitochondrial adaptation and/or dysfunction as components to hypertensive vascular dysfunction. While mitochondria are indispensable to maintain cellular metabolism, they also participate in adaptive and maladaptive cell/tissue responses via several retro grade signaling pathways. DRP1 plays a major role in mitochondrial quality control. However, whether DRP1 is involved in mitochondrial dysfunction and endothelial inflammation during development of HTN remains unknown. In the present study, we tested the hypothesis that inflammatory stimuli, through DRP1-dependent mitochondrial alteration, enhance endothelial inflammation. In cultured rat aortic endothelial cells (RAECs), TNFα (10 μg/mL) transiently induced mitochondrial fission maximally at 3h which was inhibited using a mitochondrial fission inhibitor, Mdivi1 (10 μM) (0.16±0.04 vs 0.10±0.02 mitochondria fragmentation count with MitoTracker, p<.01 ). TNFα and FCCP (a fission agonist, 10 μM) increased THP-1 monocyte adhesion to RAECs, which was also inhibited with Mdivi1 (256±17 vs 139±16 for TNFα, 238±30 vs 156±14 for FCCP, attached cells per field scanned, p<.01 ). Likewise, mdivi1 and adenoviruses encoding siRNA for DRP1 or dominant-negative K38A DRP1 (50 moi) attenuated TNFα-induced VCAM-1 induction in RAECs. TNFα increased aerobic respiration, which was prevented by mdivi1 or ER stress inhibitor PBA (10 mM). Inhibition of ER stress, glycolysis or mitochondrial respiration using PBA, 2-DG (1 mg/mL) or oligomycin (1 μM) prevented VCAM-1 induction. However, suppression of TNFα-induced mitochondrial ROS production by mito-Tempo (25 nM) was unable to prevent VCAM-1 induction. In C57BL6 mice receiving AngII (1000 ng/kg/min, 2 weeks) infusion, treatment with Mdivi-1 (25 mg/kg ip every other day) or PBA (1g/kg/day) prevented vascular VCAM-1 induction. In conclusion, our data suggests a critical role for ER stress and subsequent functional and structural remodeling of mitochondria induced by DRP1 in mediating endothelial inflammatory activation in HTN.

scholarly journals Deletion of neutral endopeptidase exacerbates intestinal inflammation induced by Clostridium difficiletoxin A

2001 ◽  
Vol 281 (2) ◽  
pp. G544-G551 ◽  
Author(s):  
Kimberly S. Kirkwood ◽  
Nigel W. Bunnett ◽  
John Maa ◽  
Ignazio Castagliolo ◽  
Bao Liu ◽  
...  
Keyword(s):  
Acute Inflammation ◽  
Intestinal Inflammation ◽  
Inflammatory Responses ◽  
Fluid Secretion ◽  
Neutral Endopeptidase ◽  
Myeloperoxidase Activity ◽  
Wild Type ◽  
Neutrophil Accumulation ◽  
Genetic Deletion ◽  
Neurokinin 1

Toxin A (TxA) of Clostridium difficile induces acute inflammation of the intestine initiated by release of substance P (SP) and activation of the neurokinin-1 receptor. However, the mechanisms that terminate this response are unknown. We determined whether the SP-degrading enzyme neutral endopeptidase (NEP, EC 3.4.24.11 ) terminates TxA-induced enteritis. We used both genetic deletion and pharmacological inhibition of NEP to test this hypothesis. In wild-type mice, instillation of TxA (0.5–5 μg) into ileal loops for 3 h dose dependently increased ileal fluid secretion, stimulated granulocyte transmigration determined by myeloperoxidase activity, and caused histological damage characterized by depletion of enterocytes, edema, and neutrophil accumulation. Deletion of NEP reduced the threshold secretory and inflammatory dose of TxA and exacerbated the inflammatory responses by more than twofold. This exacerbated inflammation was prevented by pretreatment with recombinant NEP. Conversely, pretreatment of wild-type mice with the NEP inhibitor phosphoramidon exacerbated enteritis. Thus NEP terminates enteritis induced by C. difficile TxA, underlying the importance of SP degradation in limiting neurogenic inflammation.

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