Project description:The glucocorticoid-activated glucocorticoid receptor (GR) regulates cellular stress pathways by binding to genomic regulatory elements of target genes and recruiting coregulator proteins to remodel chromatin and regulate transcription complex assembly. The coregulator Hydrogen peroxide-inducible clone 5 (Hic-5) is required for glucocorticoid regulation of some genes, but not others, and blocks regulation of a third gene set. Hic-5 inhibits GR binding to blocked genes but not other glucocorticoid-regulated genes. Site-specific blocking of GR binding is due to gene-specific requirements for ATP-dependent chromatin remodeling enzymes. We investigate whether ATPases CHD9 and BRM were required for GR occupancy at GR binding sites near Hic-5 blocked genes.
Project description:The glucocorticoid-activated glucocorticoid receptor (GR) regulates cellular stress pathways by binding to genomic regulatory elements of target genes and recruiting coregulator proteins to remodel chromatin and regulate transcription complex assembly. The coregulator Hydrogen peroxide-inducible clone 5 (Hic-5) is required for glucocorticoid regulation of some genes, but not others, and blocks regulation of a third gene set. Hic-5 inhibits GR binding to blocked genes but not other glucocorticoid-regulated genes. Site-specific blocking of GR binding is due to gene-specific requirements for ATP-dependent chromatin remodeling enzymes. We investigate the effects of Hic-5 and dexamethasone on chromatin accessibility at GR binding sites near Hic-5 blocked genes and non-blocked genes.
Project description:ARGLU1 is a Transcriptional Coactivator and Splicing Regulator Important for Stress Hormone Signaling and Development Stress hormones bind and activate the glucocorticoid receptor (GR) in many tissues including the brain. We identified arginine and glutamate rich 1 (ARGLU1) in a screen for new modulators of glucocorticoid signaling in the CNS. Biochemical studies show that the glutamate rich C-terminus of ARGLU1 coactivates multiple nuclear receptors including the glucocorticoid receptor (GR) and the arginine rich N-terminus interacts with splicing factors and binds to RNA. RNA-seq of neuronal cells depleted of ARGLU1 revealed significant changes in the expression and alternative splicing of distinct genes involved in neurogenesis. Loss of ARGLU1 is embryonic lethal in mice, and knockdown in zebrafish causes neurodevelopmental and heart defects. Treatment with dexamethasone, a GR activator, also induces changes in the pattern of alternatively spliced genes, many of which were lost when ARGLU1 was absent. Importantly, the genes found to be alternatively spliced in response to glucocorticoid treatment were distinct from those under transcriptional control by GR, suggesting an additional mechanism of glucocorticoid action is present in neuronal cells. Our results thus show that ARGLU1 is a novel factor for embryonic development that modulates basal transcription and alternative splicing in neuronal cells with consequences for glucocorticoid signaling.
Project description:ARGLU1 is a Transcriptional Coactivator and Splicing Regulator Important for Stress Hormone Signaling and Development Stress hormones bind and activate the glucocorticoid receptor (GR) in many tissues including the brain. We identified arginine and glutamate rich 1 (ARGLU1) in a screen for new modulators of glucocorticoid signaling in the CNS. Biochemical studies show that the glutamate rich C-terminus of ARGLU1 coactivates multiple nuclear receptors including the glucocorticoid receptor (GR) and the arginine rich N-terminus interacts with splicing factors and binds to RNA. RNA-seq of neuronal cells depleted of ARGLU1 revealed significant changes in the expression and alternative splicing of distinct genes involved in neurogenesis. Loss of ARGLU1 is embryonic lethal in mice, and knockdown in zebrafish causes neurodevelopmental and heart defects. Treatment with dexamethasone, a GR activator, also induces changes in the pattern of alternatively spliced genes, many of which were lost when ARGLU1 was absent. Importantly, the genes found to be alternatively spliced in response to glucocorticoid treatment were distinct from those under transcriptional control by GR, suggesting an additional mechanism of glucocorticoid action is present in neuronal cells. Our results thus show that ARGLU1 is a novel factor for embryonic development that modulates basal transcription and alternative splicing in neuronal cells with consequences for glucocorticoid signaling.
Project description:The glucocorticoid receptor (GR) is a crucial drug target in multiple myeloma as its activation with glucocorticoids effectively triggers myeloma cell death. However, as high-dose glucocorticoids are also associated with deleterious side effects, novel approaches are urgently needed to improve GR’s action in myeloma. Here we reveal a functional crosstalk between GR and the mineralocorticoid receptor (MR) that culminates in improved myeloma cell killing. We show that the GR agonist Dexamethasone (Dex) downregulates MR levels in a GR-dependent way in myeloma cells. Co-treatment of Dex with the MR antagonist Spironolactone (Spi) enhances Dex-induced cell killing in primary, newly diagnosed GC-sensitive myeloma cells, while in a relapsed GC-resistant setting, Spi alone induces distinct myeloma cell killing. On a mechanistic level, we find that a GR-MR crosstalk is arising from an endogenous interaction between GR and MR in myeloma cells. Quantitative dimerization assays show that Spi reduces Dex-induced GR-MR heterodimerization and completely abolishes Dex-induced MR MR homodimerization but leaves GR-GR homodimerization intact. Unbiased transcriptomics further reveals that c-myc and many of its target genes are downregulated most by Dex and Spi combined, while proteomics analyses identify that several metabolic hallmarks are modulated most by this combination treatment. Finally, we identified a subset of Dex+Spi downregulated genes and proteins that may predict prognosis in the CoMMpass patient cohort. Our study demonstrates that GR-MR crosstalk is therapeutically relevant in myeloma as it provides novel strategies towards glucocorticoid-based dose-reduction.
Project description:Glucocorticoid receptor (GR) is an essential transcription factor (TF), controlling metabolism, development and immune responses. SUMOylation regulates chromatin occupancy and target gene expression of GR in a locus-selective manner, but the mechanism of regulation has remained elusive. Here, we show using selective isolation of chromatin-associated proteins that the protein network around chromatin-bound GR is affected by SUMOylation, with several nuclear receptor coregulators and chromatin modifiers being more avidly associated with SUMOylation-deficient than SUMOylation competent GR. This difference is reflected in our chromatin accessibility and gene expression data, showing that the SUMOylation-deficient GR is more potent in opening chromatin at glucocorticoid-regulated enhancers and inducing expression of their target loci. Our results thus show that SUMOylation determines GR specificity by regulating the chromatin protein network and accessibility at GR-driven enhancers. We speculate that a similar mechanism is utilized by many other SUMOylated TFs.