Project description:To better understand the molecular mechanisms underlying PPARG tumor suppressor role in basal cells, we studied the effect of PPARG expression on gene expression levels in UMUC6 cells that express low endogeneous expression levels of PPARG
Project description:PPARγ regulates glucose and lipid homeostasis, insulin signaling and adipocyte differentiation. Here we report the skipping of exon 5 as legitimate splicing event generating PPARγΔ5, a new truncated isoform lacking the ligand binding domain. PPARγΔ5 is endogenously expressed in human adipose tissue and during adipocyte differentiation, lacks the ligand-dependent transactivation ability and acts as dominant negative reducing PPARγ activity. Ligand-mediated PPARγ activation induces exon 5 skipping in a negative feedback loop, suggesting alternative splicing as a new mechanism regulating PPARγ activity. PPARγΔ5 over-expression modifies PPARγ-induced transcriptional network, significantly impairing the differentiation ability of adipocyte precursor cells. Additionally, PPARγΔ5 expression in subcutaneous adipose tissue positively correlates with BMI in two independent cohorts of obese and diabetic patients. From a functional perspective, PPARγΔ5 mimics PPARG dominant negative mutated receptors, possibly contributing to adipose tissue dysfunctions. These findings open unexplored scenario in PPARG regulation and PPARγ-related diseases.
Project description:In order to gain insights into how PPARg regulates different facets of dendritic cell (DC) differentiation, we sought to identify PPARg regulated genes and gene networks in monocyte-derived dendritic cells using global gene expression profiling. We employed an exogenous ligand activation approach using a selective PPARg ligand (rosiglitazone abbreviated as RSG). In addition, we have defined culture conditions in which human serum (HS) induces PPARg activation via a yet uncharacterized endogenous mechanism. We also compared the gene expression profile of developing dendritic cells obtained from patients harboring dominant negative mutations of the PPARg receptor (C114R and C131Y). Keywords: ligand response
Project description:We find that Pparg is a master regulator of cell specification during urothelial homeostasis, driving a luminal differentiation program via retinoid signaling. Interestingly, expression of activated Pparg in basal cells only drives tumor formation when they are in an activated state, that are in an activated state, induces formation of luminal tumors with papillary morphology, Expression of an activated form of Pparg induces basal cells at homeostasis, to differentiate directly into luminal cells. In a BBN mouse model which produces basal subtypes tumors in wild type animals, activated Pparg drives formation of luminal tumors, suggesting that this transcription factor is a master regulator of luminal differentiation, as has been suggested from in vitro studies.
Project description:Analysis of PPARg targets in adipose progenitor cells at gene expression level. The hypothesis tested in the present study was that PPARg control adipose nichenenesis and niche occupancy through regulating downstream targets in adipose progenitors. Results provide important information of the response of PPARg deletion in adipose progenitor cells, such as specific up- or down-regulated genes involved in cellular adhesion, chemotaxis and mural cell to endothelial interactions.
Project description:Our data indicated that activation of the PPARg nuclear receptor induces a retinoid response in human dendritic cells. In order to assess the contribution of retinoid signaling to the PPARg response we decided to use a combination of pharmacological activators and inhibitors of these pathways. Cells were treated with the synthetic PPARg ligand rosiglitazone (RSG), or with RSG along with the RARa antagonist (AGN193109) to block RARa mediated gene expression, or the RARa specific agonists (AM580) alone. This design allows one to determine if retinoid signaling is a downstream event of PPARg activation and what portion of PPARg regulated genes are regulated via induced retinoid signaling. Keywords: ligand response
Project description:Conditional macrophage-specific PPARg knockout mice were generated on C57Bl/6 background by breeding PPARg fl/- (one allele is floxed, the other is null) and lysozyme Cre transgenic mice. PPARg and IL-4 signaling was analyzed on bone marrow-derived macrophages. Bone marrow of 3 mice per group was isolated and differentiated to macrophages with M-CSF (20 ng/ml). 20 ng/ml IL-4 was used to induce alternative macrophage activation and 1 uM Rosiglitazone (RSG) was used to activate PPARg. From each mouse 4 samples were generated: 1. M-CSF, 2. M-CSF+RSG, 3. IL-4 and 4. IL-4+RSG. All compounds were added throughout the whole differentiation process, and fresh media was added every other day. Control cells were treated with vehicle (DMSO:ethanol). After 10 days, RNA was isolated and gene expression profiles were analyzed using Mouse Genome 430 2.0 microarrays from Affymetrix. 3 PPARg +/- LysCre and 3 PPARg fl/- LysCre mice were used to isolate bone marrow and from each macrophages were differentiated with or without IL-4 and simultaneously treated with vehicle or RSG. Altogether we analyzed 24 samples with 3 biological replicates as below.
Project description:Peroxisome Proliferator-Activated Receptor-gamma (PPARG) is a nuclear hormone receptor that was originally described as a master regulator of adipogenesis but could also promote cellular differentiation in a number of epithelium. PPARG also serves as an important regulator in anti-inflammatory activity after a variety of injuries, acting in part by antagonizing the NF-kB pathway. Moreover, the expression of PPARG is strongly down regulated in the basal subtype of bladder cancer, suggesting that its removal might be essential in tumorigenesis. In urothelial cells, it has been shown that PPARG promotes urothelial differentiation in vitro, but its function in vivo remains unexplored. The urothelium is a stratified epithelium that serves as a barrier between the urinary tract and blood. It consists of terminally differentiated umbrella cells, intermediate cells which serve as umbrella cell progenitors; and unipotent basal cells. To determine the role of PPARG in vivo, we used Cre-Lox recombination to conditionally delete the Pparg gene in the mouse urothelium using the ShhCre driver, which drives recombination in basal and intermediate cells, and their respective daughters. Interestingly, ShhCre;Ppargfl/fl mutants lack umbrella and intermediate cells, but have an abnormal cell population negative for classical urothelial markers instead. Furthermore, we observed an increase of KRT14+ population in the basal compartment and squamous features in the mutant urothelium. Expression profile analysis suggested PPARG regulates metabolism, urothelial differentiation and innate immune response. We further challenged the Pparg mutant urothelium with acute injury. In wild type animals, urinary tract infection (UTI) with uropathogenic E.coli results in a transient innate immune response, followed by a completed regernation within 2 weeks. When ShhCre;Ppargfl/fl mutants were challenged with urinary tract infection, the innate immune response was not resolved even after several weeks and the Pparg ablated urothelium exhibited squamous metaplasia. RNAseq data suggested that PPARG plays a role in regulating squmous differentiation and NFkB signial pathway. Together these findings suggest that PPARG is essential for the normal differentiation of the urothelium and is a potent regulator of the inflammatory response after UTI. Understanding the link between the loss of PPARG, chronic inflammation and tumorigenesis in the urothelium could shed light on the urothelial differentiation network and pave the way for the development of therapeutic approaches to various urinary diseases.
Project description:Conditional macrophage-specific PPARg knockout mice were generated on C57Bl/6 background by breeding PPARg fl/- (one allele is floxed, the other is null) and lysozyme Cre transgenic mice. PPARg and IL-4 signaling was analyzed on bone marrow-derived macrophages. Bone marrow of 3 mice per group was isolated and differentiated to macrophages with M-CSF (20 ng/ml). 20 ng/ml IL-4 was used to induce alternative macrophage activation and 1 uM Rosiglitazone (RSG) was used to activate PPARg. From each mouse 4 samples were generated: 1. M-CSF, 2. M-CSF+RSG, 3. IL-4 and 4. IL-4+RSG. All compounds were added throughout the whole differentiation process, and fresh media was added every other day. Control cells were treated with vehicle (DMSO:ethanol). After 10 days, RNA was isolated and gene expression profiles were analyzed using Mouse Genome 430 2.0 microarrays from Affymetrix.