Project description:The nuclear receptor PPAR gamma is required for adipocyte differentiation, but its role in mature adipocytes is less clear. Here we report that knockdown of PPAR gamma expression in 3T3-L1 adipocytes returned the expression of most adipocyte genes towards preadipocyte levels. Consistently, down regulated but not up regulated genes showed strong enrichment of PPAR gamma binding. Surprisingly, not all adipocyte genes were reversed and the adipocyte morphology was maintained for an extended period after PPAR gamma depletion. To explain this, we focused on transcriptional regulators whose adipogenic regulation was not reversed upon PPAR gamma depletion. We identified GATA2, a transcription factor whose down-regulation early in adipogenesis is required for preadipocyte differentiation, remaining low after PPAR gamma knockdown. Forced expression of GATA2 in mature adipocytes complemented PPAR gamma depletion and impaired adipocyte functionality with a more preadipocyte- like gene expression profile. Ectopic expression of GATA2 in adipose tissue in vivo had similar effect on adipogenic gene expression. These results suggest that PPAR gamma-independent down regulation of GATA2 prevents reversion of mature adipocytes after PPAR gamma depletion. Keywords: cell type comparison, Gata2, PPAR gamma, adipocyte, preadipocytes, differentiation
Project description:The nuclear receptor PPAR gamma is required for adipocyte differentiation, but its role in mature adipocytes is less clear. Here we report that knockdown of PPAR gamma expression in 3T3-L1 adipocytes returned the expression of most adipocyte genes towards preadipocyte levels. Consistently, down regulated but not up regulated genes showed strong enrichment of PPAR gamma binding. Surprisingly, not all adipocyte genes were reversed and the adipocyte morphology was maintained for an extended period after PPAR gamma depletion. To explain this, we focused on transcriptional regulators whose adipogenic regulation was not reversed upon PPAR gamma depletion. We identified GATA2, a transcription factor whose down-regulation early in adipogenesis is required for preadipocyte differentiation, remaining low after PPAR gamma knockdown. Forced expression of GATA2 in mature adipocytes complemented PPAR gamma depletion and impaired adipocyte functionality with a more preadipocyte- like gene expression profile. Ectopic expression of GATA2 in adipose tissue in vivo had similar effect on adipogenic gene expression. These results suggest that PPAR gamma-independent down regulation of GATA2 prevents reversion of mature adipocytes after PPAR gamma depletion. Experiment Overall Design: This dataset consists of three sample groups: preadipocytes, control siRNA treated adipocytes, and PPAR gamma siRNA treated adipocytes. Each sample group consists of three replicates samples. Each sample was hybridized to a separate array for a total of nine arrays. Experiment Overall Design: Technical replicates: Pread 1, Pread 2, Pread 3 Experiment Overall Design: Technical replicates: Cont siRNA 1, Cont siRNA 2, Cont siRNA 3 Experiment Overall Design: Technical replicates: PPAR gamma siRNA 1, PPAR gamma siRNA 2, PPAR gamma siRNA 3
Project description:Pharmacological activation of peroxisome proliferator-activated receptor gamma (PPAR-γ) is a convenient and promising tactic for promoting beige adipocyte biogenesis to combat obesity-related metabolic disorders. However, thiazolidinediones (TZDs), the full agonist of PPAR-γ exhibits severe side effects in animal model and clinical uses. Therefore, it is emerging to develop efficient and safe PPAR-γ modulators for metabolic disease treatment. Here, by utilizing comprehensive methods, we report a previously unidentified ligand binding pocket (LBP) in PPAR-γ and link it to beige adipocyte differentiation. Further virtual screening from 4097 natural compounds based on this novel LBP, we discover NJT-2, a terpenoid compound, can bind to PPAR-γ induce co-activator recruitment and effectively activate PPAR-γ mediated transcription of beige adipocyte program. Importantly, in mouse model, NJT-2 administration efficiently promotes beige adipocyte biogenesis and improve obesity-associated metabolic dysfunction with significant lower adverse effects than those observed in TZD. Our results not only provide an advanced molecular insight into the structural ligand binding details in PPARg, but also develop its linked selective and safe agonist for obesity treatment.
Project description:Genome-wide profiling of PPAR?:RXR and RNA polymerase II reveals temporal activation of distinct metabolic pathways in RXR dimer composition during adipogenesis. Chromatin immunoprecipitation combined with deep sequencing was performed to generate genome-wide maps of peroxisome prolifelator-activated receptor gamma (PPARg) and retinoid X receptor (RXR) binding sites, and RNA polymerase II (RNAPII) occupancy at high resolution throughout adipocyte differentiation of 3T3-L1 cells. The data provides the first positional and temporal map PPAR? and RXR occupancy during adipocyte differentiation at a global scale. The number of PPAR?:RXR shared binding sites is steadily increasing from D0 to D6. At Day6 there are over 5000 high confidence shared PPARy:RXR binding sites. We show that at the early days of differentiation several of these sites bind not only PPAR?:RXR but also other RXR dimers. The data also provides a comprehensive temporal map of RNAPII occupancy at genes throughout 3T3-L1 adipogenesis thereby uncovering groups of similarly regulated genes belonging to glucose and lipid metabolic pathways. The majority of the upregulated but very few downregulated genes have assigned PPAR?:RXR target sites, thereby underscoring the importance of PPAR?:RXR in gene activation during adipogenesis and indicating that a hitherto unrecognized high number of adipocyte genes are directly activated by PPAR?:RXR Examination of PPARg and RXR bindingsites during adipocyte differentiation (day 0 to 6) and association with transcription via RNAPII occupancy.
Project description:We report that both conventional and adipose-specific Naa10p deletions in mice result in increased energy expenditure, thermogenesis, beige adipocyte differentiation and activation. Mechanistically, Naa10p acetylates the N-terminus of Pgc1-alpha and prevents it from interacting with Ppar[gamma] to activate key genes, such as Ucp1, involved in beige adipocyte function.
Project description:Adipogenesis is tightly controlled by a complex network of transcription factors acting at different stages of differentiation. Peroxisome proliferator-activated receptor gamma (PPAR gamma) and CCAAT/enhancer binding protein (C/EBP) family members are key regulators of this process. We have employed DNase I hypersensitive site analysis to investigate the genome-wide changes in chromatin structure that accompany the binding of adipogenic transcription factors. These analyses revealed a dramatic and dynamic modulation of the chromatin landscape during the first hours of adipocyte differentiation that coincides with cooperative binding of multiple early transcription factors (including glucocorticoid receptor, retinoid X receptor, Stat5a, C/EBPbeta and -delta) to transcription factor 'hotspots'. Our results demonstrate that C/EBPbeta marks a large number of these transcription factor 'hotspots' prior to induction of differentiation and chromatin remodeling and is required for their establishment. Furthermore, a subset of early remodeled C/EBP binding sites persists throughout differentiation and is later occupied by PPAR gamma , indicating that early C/EBP family members, in addition to their well established role in activation of PPAR gamma transcription, may act as pioneering factors for PPAR gamma binding. DNase I hypersensitive chromatin regions and transcription factor binding sites were identified at various time points of 3T3-L1 differentiation using DHS-seq and ChIP-seq, respectively.
Project description:We identify fibroblast growth factor 1 (FGF1) as a critical transducer in adipose tissue remodeling and link its regulation to peroxisome proliferator activated-receptor ? (PPAR?), the adipocyte master regulator and target of the thiazolidinedione (TZD) class of insulin sensitizing drugs. We show that FGF1 is highly induced in adipose tissue in response to high-fat diet (HFD) and that mice lacking FGF1 develop an aggressive diabetic phenotype coupled to aberrant adipose expansion when challenged with HFD. Mechanistically, we show that transcription of FGF1 is directly regulated by an adipocyte-selective proximal PPAR response element, and that this PPAR?-FGF1 axis is evolutionarily conserved in mammals. This work describes the first phenotype of the FGF1 knockout mouse and establishes FGF1 as a new member of the NR-FGF axis critical for maintaining metabolic homeostasis and insulin sensitization. Total RNA was obtained from epidydimal white adipose tissue (eWAT) and livers from 6 month old wild-type and FGF1-/- mice after 16 weeks on normal chow or high-fat diets.
Project description:Adipogenesis is tightly controlled by a complex network of transcription factors acting at different stages of differentiation. Peroxisome proliferator-activated receptor gamma (PPAR gamma) and CCAAT/enhancer binding protein (C/EBP) family members are key regulators of this process. We have employed DNase I hypersensitive site analysis to investigate the genome-wide changes in chromatin structure that accompany the binding of adipogenic transcription factors. These analyses revealed a dramatic and dynamic modulation of the chromatin landscape during the first hours of adipocyte differentiation that coincides with cooperative binding of multiple early transcription factors (including glucocorticoid receptor, retinoid X receptor, Stat5a, C/EBPbeta and -delta) to transcription factor 'hotspots'. Our results demonstrate that C/EBPbeta marks a large number of these transcription factor 'hotspots' prior to induction of differentiation and chromatin remodeling and is required for their establishment. Furthermore, a subset of early remodeled C/EBP binding sites persists throughout differentiation and is later occupied by PPAR gamma , indicating that early C/EBP family members, in addition to their well established role in activation of PPAR gamma transcription, may act as pioneering factors for PPAR gamma binding.
Project description:We identify fibroblast growth factor 1 (FGF1) as a critical transducer in adipose tissue remodeling and link its regulation to peroxisome proliferator activated-receptor γ (PPARγ), the adipocyte master regulator and target of the thiazolidinedione (TZD) class of insulin sensitizing drugs. We show that FGF1 is highly induced in adipose tissue in response to high-fat diet (HFD) and that mice lacking FGF1 develop an aggressive diabetic phenotype coupled to aberrant adipose expansion when challenged with HFD. Mechanistically, we show that transcription of FGF1 is directly regulated by an adipocyte-selective proximal PPAR response element, and that this PPARγ-FGF1 axis is evolutionarily conserved in mammals. This work describes the first phenotype of the FGF1 knockout mouse and establishes FGF1 as a new member of the NR-FGF axis critical for maintaining metabolic homeostasis and insulin sensitization.