Project description:Glucocorticoids are a class of steroid hormones that bind to and activate the Glucocorticoid Receptor, which then positively or negatively regulates transcription of many genes that govern multiple important physiological pathways such as inflammation and metabolism of glucose, fat and bone. Previous studies focusing on single coregulators demonstrated that each coregulator is required for regulation of only a subset of all the genes regulated by a steroid hormone. We hypothesize that the gene-specific patterns of coregulators may correspond to specific physiological pathways such that different coregulators modulate the pathway-specificity of hormone action and thus provide a mechanism for fine tuning of the hormone response. Global analysis of glucocorticoid-regulated gene expression after siRNA mediated depletion of coregulators confirmed that each coregulator acted in a selective and gene-specific manner and demonstrated both positive and negative effects on glucocorticoid-regulated expression of different genes. Each coregulator supported hormonal regulation of some genes and opposed hormonal regulation of other genes (coregulator-modulated genes), blocked hormonal regulation of a second class of genes (coregulator-blocked genes), and had no effect on hormonal regulation of a third gene class (coregulator-independent genes). In spite of previously demonstrated physical and functional interactions among these four coregulators, the majority of the several hundred modulated and blocked genes for each of the four coregulators tested were unique to that coregulator. Finally, pathway analysis on coregulator-modulated genes supported the hypothesis that individual coregulators may regulate only a subset of the many physiological pathways controlled by glucocorticoids.
Project description:The closely related transcription factors (TFs), estrogen receptors ER? and ER?, regulate divergent gene expression programs and proliferative outcomes in breast cancer. Utilizing MCF-7 breast cancer cells with ER?, ER?, or both receptors as a model system to define the basis of differing response specification by related TFs, we show that these TFs and their key coregulators, SRC3 and RIP140, generate overlapping as well as unique chromatin-binding and transcription-regulating modules. Cistrome and transcriptome analyses and use of clustering algorithms delineated 11 clusters representing different chromatin-bound receptor and coregulator assemblies that could be functionally associated through enrichment analysis with distinct patterns of gene regulation and preferential coregulator usage, RIP140 with ER? and SRC3 with ER?. The receptors modified each other’s transcriptional effect, and ER? countered the proliferative drive of ER? through several novel mechanisms associated with specific binding site clusters. Our findings delineate distinct TF-coregulator assemblies that function as control nodes specifying precise patterns of gene regulation, proliferation, and metabolism, as exemplified by two of the most important nuclear hormone receptors in human breast cancer. Examination of Estrogen Receptors alpha and beta and their coregulators SRC3 and RIP140 in different cell types
Project description:Caloric restriction (CR) improves metabolic health. To define how the hepatic glucocorticoid receptor (GR) supports CR-driven metabolic adaptation, we profiled its liver interactome by chromatin immunoprecipitation-mass spectrometry (ChIP-MS). Mouse livers were collected at ZT12 (glucocorticoid peak) under ad libitum or CR feeding. GR immunoprecipitates were compared to IgG controls to identify GR-associated proteins. The dataset reveals diet-dependent GR protein complexes, including transcriptional factors and metabolic coregulators, and serves as a resource for factors linking hormonal and nutritional signals to CR-induced hepatic reprogramming.
Project description:Glucocorticoids play central roles in the regulation of energy metabolism by shifting it toward catabolism, while AMPK is the master regulator of energy homeostasis, sensing energy depletion and stimulating pathways of increasing fuel uptake and saving on peripheral supplies. We showed here that AMPK regulates glucocorticoid actions on carbohydrate metabolism by targeting the glucocorticoid receptor (GR) and modifying transcription of glucocorticoid-responsive genes in a tissue- and promoter-specific fashion. Activation of AMPK in rats reversed glucocorticoid-induced hepatic steatosis and suppressed glucocorticoid-mediated stimulation of glucose metabolism. Transcriptomic analysis in the liver suggested marked overlaps between the AMPK and glucocorticoid signaling pathways directed mostly from AMPK to glucocorticoid actions. AMPK accomplishes this by phosphorylating serine 211 of the human GR indirectly through phosphorylation and consequent activation of p38 MAPK and by altering attraction of transcriptional coregulators to DNA-bound GR. In human peripheral mononuclear cells, AMPK mRNA expression positively correlated with that of glucocorticoid-responsive GILZ, which correlated also positively with the body mass index of subjects. These results indicate that the AMPK-mediated energy control system modulates glucocorticoid action at target tissues. Since increased action of glucocorticoids is associated with development of metabolic disorders, activation of AMPK could be a promising target for developing pharmacologic interventions to these pathologies. We tested the hypothesis by treateing rats with the synthetic glucocorticoid dexamethasone and the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR).
Project description:LC-MS data and DIA-NN search files relating to: PU.1 Eviction at Lymphocyte-Specific Chromatin Domains Mediates Glucocorticoid Response in Acute Lymphoblastic Leukemia.
Abstract: The epigenetic landscape plays a critical role in the onset and evolution of various malignancies, but its therapeutic utility remains underutilized. Glucocorticoids are an essential part of many multi-agent treatment regimens for lymphoid malignancies. However, the emergence of glucocorticoid resistance is a significant barrier to cure, which is in part due to epigenetic alterations, including aberrant chromatin accessibility and hypermethylation at lymphocyte-specific glucocorticoid-response elements (GREs). To gain a deeper understanding of regulatory mechanisms leading to these epigenetic alterations, we conducted a multi-omics study, including chromosome conformation capture sequencing (HiC), to examine changes in the 3D genome structure following the in vivo treatment of acute lymphoblastic leukemia (ALL) patient-derived xenografts (PDXs) with glucocorticoid. We found that glucocorticoid treatment led to distinct patterns of topologically associated domains (TADs) in glucocorticoid sensitive compared to resistant PDXs. Furthermore, we show that these TADs were primed by the development-related pioneer transcription factor PU.1, which extensively interacts with the glucocorticoid receptor (GR) exclusively in glucocorticoid-sensitive ALL PDXs. An integrative analysis of rapid immunoprecipitation mass spectrometry of endogenous protein (RIME) and ChIP-seq revealed that PU.1 binding was associated with lymphocyte-specific activation of GREs and GRE-interacting super-enhancers. The PU.1-associated TADs modulated epigenetic marks, and particularly the eviction of PU.1 promoted GR binding and the expression of signature genes, including BIM, ZBTB16 and RASA1, mediating glucocorticoid-induced apoptosis in ALL. These findings were phenocopied using a PU.1 inhibitor DB2313 to restore glucocorticoid sensitivity in ALL. Taken together, this study identified a new epigenetic pathway integrating PU.1 priming and PU.1-GR interaction which ultimately leads to PU.1 eviction in ALL. This pathway provides the first link between the activity of a lineage-specific transcription factor and epigenetic modulators mediating the response to glucocorticoids and thus offers a new avenue to translate fundamental epigenetic research into the clinic.
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.