Project description:Excessive glucocorticoid exposure is associated with significant metabolic side effects, partly attributed to the transcriptional regulation of adipogenesis by the Glucocorticoid receptor (GR). However, emerging evidence suggests the involvement of alternative pathways beyond GR activation, which are inadequately explored. Through quantitative phosphoproteomics analysis, we identified a significant enrichment of rapidly phosphorylated proteins harboring the RxxS motif following glucocorticoid exposure. Notably, a subset of these proteins undergoes phosphorylation at the RxxS motif by Serum- and glucocorticoid-induced kinase 3 (SGK3) upon glucocorticoid stimulation in preadipocytes. SGK3 emerges as a critical mediator of glucocorticoid-induced preadipocyte differentiation, supported by genetic ablation and pharmacological inhibition experiments that demonstrate impaired adipogenesis both in vitro and in vivo. Mechanistically, upon glucocorticoid stimulation, SGK3 translocates to the nucleus and directly interacts with the core ATPase subunit of the BAF chromatin remodeling complex, BRG1, leading to phosphorylation at threonine 428 and serine 1417 residues. This phosphorylation event prevents proteasomal degradation of BRG1, facilitating chromatin remodeling essential for adipogenesis. Furthermore, Sgk3 knockout mice exhibit resistance to obesity induced by either glucocorticoids or a high-fat diet (HFD). These findings illuminate novel roles of glucocorticoids beyond GR-mediated transcriptional control, highlighting SGK3 as a promising therapeutic target for mitigating metabolic side effects associated with glucocorticoid therapy.
Project description:Glucocorticoids induce rapid apoptosis of rat primary thymocytes through mechanisms requiring altered gene expression. The determination of genes regulating glucocorticoid-induced apoptosis of lymphocytes has received considerable attention. However, the role of specific non-coding microRNAs in the regulation of glucocorticoid-induced apoptosis of lymphocytes is poorly defined. Using deep sequencing analysis, we have identified microRNAs differentially expressed during glucocorticoid-induced apoptosis of rat primary thymocytes. We have also identified numerous loci that harbor probable novel microRNAs. Furthermore, we have validated the glucocorticoid-responsive expression of 2 novel microRNAs in the apoptotic rat primary thymocyte. These 2 novel microRNAs are predicted to target numerous messenger RNAs throughout the genome. Using whole genome expression analysis, we now seek to correlate the altered expression of these novel microRNAs with the expression of their predicted target mRNAs during glucocorticoid-induced apoptosis. Changes in gene expression during glucocorticoid-induced apoptosis of rat primary thymocyes (3 biological replicates) were measured after 6 hours of 100nM dexamethasone treatment in-vitro.
Project description:Vascular inflammation is present in many cardiovascular diseases and exogenous glucocorticoids have traditionally been used as a therapy to suppress inflammation. However, recent data has shown that endogenous glucocorticoids, acting through the endothelial glucocorticoid receptor, act as negative regulators of inflammation. Here we performed chromatin immunoprecipitation for the glucocorticoid receptor followed by next-gen sequencing in mouse endothelial cells to investigate how the endothelial glucocorticoid receptor regulates vascular inflammation. We identified a novel role of the Wnt signaling pathway in this setting and show that loss of the endothelial glucocorticoid receptor results in up regulation of Wnt signaling both in vitro and in vivo using our validated mouse model. Further we demonstrate glucocorticoid receptor regulation of a key gene in the Wnt pathway via a novel glucocorticoid response element gleaned from our genomic data. These results suggest a novel role for endothelial Wnt signaling modulation in states of vascular inflammation.
Project description:Vascular inflammation is present in many cardiovascular diseases and exogenous glucocorticoids have traditionally been used as a therapy to suppress inflammation. However, recent data has shown that endogenous glucocorticoids, acting through the endothelial glucocorticoid receptor, act as negative regulators of inflammation. Here we performed chromatin immunoprecipitation for the glucocorticoid receptor followed by next-gen sequencing in mouse endothelial cells to investigate how the endothelial glucocorticoid receptor regulates vascular inflammation. We identified a novel role of the Wnt signaling pathway in this setting and show that loss of the endothelial glucocorticoid receptor results in up regulation of Wnt signaling both in vitro and in vivo using our validated mouse model. Further we demonstrate glucocorticoid receptor regulation of a key gene in the Wnt pathway via a novel glucocorticoid response element gleaned from our genomic data. These results suggest a novel role for endothelial Wnt signaling modulation in states of vascular inflammation.
Project description:During mesenchymal stem cell (MSC) differentiation, both Wnt signaling and the development of a rigid cytoskeleton promote commitment to the osteoblastic over adipogenic lineage. β-catenin is thought to play a critical role in Wnt effects. We show that β-catenin was additive with cytoskeletal signals to prevent adipogenesis, and β-catenin knockdown promoted adipogenesis even when the actin cytoskeleton was depolymerized. β-catenin also prevented osteoblast commitment in a cytoskeletal-independent manner, with β-catenin knockdown enhancing lineage commitment. Chip-seq showed that β-catenin associated with the promoter of EZH2, a key component of the PRC2 complex that governs genome methylation. Knocking down β-catenin lowered EZH2 levels and H3K27me3 at osteogenic loci. Further, when EZH2 was inhibited, β-catenin ’s anti-differentiation effects were lost. These results indicate that regulating EZH2 activity is key to β-catenin effects on MSC to preserve MSC multipotentiality.