PPARγ lipodystrophy mutants reveal intermolecular interactions required for enhancer activation
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ABSTRACT:
PROVIDER: PRJNA819987 | ENA |
REPOSITORIES: ENA
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Project description:The peroxisome proliferator-activated receptor γ (PPARγ) is the master regulator of adipocyte differentiation, and mutations that interfere with PPARγ function cause lipodystrophy. Structural studies indicate that PPARγ domains engage in several intra- and inter-moleuclar interactions; however, how these interactions modulate the ability of PPARγ to activate target genes in a cellular context is currently poorly understood. Here we analysed the transcriptional potential of R212Q and E379K two previously uncharacterised lipodystrophy-associated PPARγ mutants that are located in distinct PPARγ domains but are both predicted to affect intermolecular interactions. Using a combination of biochemical and genome-wide approaches we show that these mutations impair binding to an overlapping subset of enhancers that are less accessible and specifically require PPARγ for chromatin remodeling. Based on these findings we propose a model in which recruitment of PPARγ to chromatin is determined by several intermolecular interfaces. Furthermore, our data exemplify that relatively subtle molecular defects in transcription factors are sufficient to significantly affect enhancer binding and thereby transcriptional output.
2022-09-08 | PXD036589 | Pride
Project description:In this setup we have used RNA-seq, ChIP-seq, and ATAC-seq to identify how natural mutations in PPARg, which leads to lipodystrophy, cause changes in transcription, chromatin landscape, transcription factor binding and enhancer activity.
2022-10-27 | GSE199426 | GEO
Project description:The E157D PPARγ mutation presents as an atypical case of familial partial lipodystrophy and diabetes in a human cohort and has a novel molecular mechanism. The mutation is located in the DNA-binding domain, has no dominant negative activity but disrupts transcription activation after the protein has bound the DNA. The mutation causes a transcriptional activation defect on many PPARγ target genes, while some genes are induced normally. A small number of non-PPARγ target genes are induced by the E157D mutant, possibly leading to the atypical features in this cohort.
2012-05-16 | GSE37990 | GEO
Project description:Adipocytes are the primary sites for fatty acid storage, but the synthesis rate of fatty acids is very low. The physiological significance of this phenomenon remains unclear. Here, we show that surplus fatty acid synthesis in adipocytes induces necroptosis and lipodystrophy. Transcriptional activation of FASN elevates fatty acid synthesis, but decreases NADPH level and increases ROS production, which ultimately leads to adipocyte necroptosis. We identify MED20, a subunit of the Mediator complex, as a negative regulator of FASN transcription. Adipocyte-specific male Med20 knockout mice progressively develop lipodystrophy, which is reversed by scavenging ROS. Further, in a murine model of HIV-associated lipodystrophy and a human patient with acquired lipodystrophy, ROS neutralization significantly improves metabolic disorders, indicating a causal role of ROS in disease onset. Our study well explains the low fatty acid synthesis rate in adipocytes, and sheds light on the management of acquired lipodystrophy.
2023-12-11 | GSE249808 | GEO
Project description:Background and objective: Combination antiretroviral therapy (cART) is associated with lipodystrophy i.e. loss of subcutaneous adipose tissue in abdomen, limbs and face and its accumulation intra-abdominally. No fat is lost dorsocervically and it can even accumulates in this region (“buffalo hump”). It is unknown how preserved dorsocervical fat differs from abdominal subcutaneous fat in HIV-1-infected cART-treated patients with (cART+LD+) and without (cART+LD-) lipodystrophy. Results: Albeit dorsocervical adipose tissue in cART+LD+ seems spared from lipoatrophy, its mitochondrial DNA (mtDNA, copies/cell) content was significantly lower (by 62%) than that of the corresponding tissue in cART+LD-. Expression of CD68 mRNA, a marker of macrophages, and numerous inflammatory genes in microarray were significantly lower in dorsocervical vs. abdominal subcutaneous adipose tissue. Genes with the greatest difference in expression between the two depots were those involved in regulation of transcription and regionalization (homeobox genes), irrespective of lipodystrophy status. There was negligible mRNA expression of uncoupling protein 1, a gene characteristic of brown adipose tissue, in either depot. Conclusions: As mtDNA is depleted even in the non-atrophic dorsocervical adipose tissue, it is unlikely that the cause of lipoatrophy is loss of mtDNA. Dorsocervical adipose tissue is less inflamed than lipoatrophic adipose tissue. It does not resemble brown adipose tissue. The greatest difference in gene expression between dorsocervical and abdominal s.c. adipose tissue is in expression of homeobox genes. We used histology, microarray, polymerase chain reaction and magnetic resonance imaging to compare dorsocervical and abdominal subcutaneous adipose tissue in cART+LD+ (n=21) and cART+LD- (n=11). The study consists of 17 patients on antiretroviral treatment who have developed lipodystrophy and 11 patients that are on similar treatment but have not developped lipodystrophy. All patients are HIV+ and have 2 adipose tissue samples taken from them (dorsocervical+abdominal).
2011-09-14 | E-GEOD-28073 | biostudies-arrayexpress
Project description:Extrachromosomal DNA (ecDNA) is prevalent in human cancers and mediates high oncogene expression through gene amplification and altered gene regulation. Gene induction typically involves cis regulatory elements that contact and activate genes on the same chromosome. Here we show that ecDNA hubs, clusters of ~10-100 ecDNAs within the nucleus, enable intermolecular enhancer-gene interactions to promote oncogene overexpression in trans. ecDNAs encoding multiple distinct oncogenes form hubs in diverse cancer cell types and primary tumors. Each ecDNA is more likely to transcribe the oncogene when spatially clustered with additional ecDNAs. ecDNA hubs are tethered by the BET protein BRD4 in a MYC-amplified colorectal cancer cell line. BET inhibitor JQ1 disperses ecDNA hubs and preferentially inhibits ecDNA-based oncogene transcription. A BRD4-bound promoter in PVT1 is ectopically fused to MYC and duplicated in ecDNA, receiving promiscuous enhancer input to drive potent MYC expression. PVT1 promoter on a heterologous episome suffices to mediate gene activation in trans by ecDNA hubs in a JQ1-sensitive manner. Systematic CRISPRi silencing of ecDNA enhancers reveal intermolecular enhancer-gene activation among multiple oncogene loci amplified on distinct ecDNAs. Together, these results demonstrate that ecDNA hubs are protein-tethered clusters of ecDNAs which enable intermolecular transcriptional regulation. ecDNA hubs may act as units of oncogene function, cooperative evolution, and potential targets for cancer therapy.
2020-11-25 | GSE159985 | GEO
Project description:Extrachromosomal DNA (ecDNA) is prevalent in human cancers and mediates high oncogene expression through gene amplification and altered gene regulation. Gene induction typically involves cis regulatory elements that contact and activate genes on the same chromosome. Here we show that ecDNA hubs, clusters of ~10-100 ecDNAs within the nucleus, enable intermolecular enhancer-gene interactions to promote oncogene overexpression in trans. ecDNAs encoding multiple distinct oncogenes form hubs in diverse cancer cell types and primary tumors. Each ecDNA is more likely to transcribe the oncogene when spatially clustered with additional ecDNAs. ecDNA hubs are tethered by the BET protein BRD4 in a MYC-amplified colorectal cancer cell line. BET inhibitor JQ1 disperses ecDNA hubs and preferentially inhibits ecDNA-based oncogene transcription. A BRD4-bound promoter in PVT1 is ectopically fused to MYC and duplicated in ecDNA, receiving promiscuous enhancer input to drive potent MYC expression. PVT1 promoter on a heterologous episome suffices to mediate gene activation in trans by ecDNA hubs in a JQ1-sensitive manner. Systematic CRISPRi silencing of ecDNA enhancers reveal intermolecular enhancer-gene activation among multiple oncogene loci amplified on distinct ecDNAs. Together, these results demonstrate that ecDNA hubs are protein-tethered clusters of ecDNAs which enable intermolecular transcriptional regulation. ecDNA hubs may act as units of oncogene function, cooperative evolution, and potential targets for cancer therapy.
2020-11-25 | GSE159972 | GEO
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.
2012-04-23 | GSE31692 | GEO
Project description:PPARγ promotes adipogenesis while Wnt proteins inhibit adipogenesis. However, the mechanisms that control expression of these positive and negative master regulators of adipogenesis remain incompletely understood. By genome-wide histone methylation profiling in preadipocytes, we find that among gene loci encoding adipogenesis regulators, histone methyltransferase (HMT) G9a-mediated repressive epigenetic mark H3K9me2 is enriched on the entire PPARγ locus. H3K9me2 and G9a levels decrease during adipogenesis, which correlates inversely with induction of PPARγ. Removal of H3K9me2 by G9a deletion enhances chromatin opening and binding of adipogenic transcription factor C/EBP-beta to PPARγ promoter, which promotes PPARγ expression. Interestingly, G9a represses PPARγ expression in an HMT activity-dependent manner but facilitates Wnt10a expression independent of its enzymatic activity. Consistently, deletion of G9a or inhibiting G9a HMT activity promotes adipogenesis. Finally, deletion of G9a in mouse adipose tissues increases adipogenic gene expression and tissue weight. Thus, by inhibiting PPARγ expression and facilitating Wnt10a expression, G9a represses adipogenesis. Examination of gene expression changes in G9a KO brown preadipocytes
2013-02-01 | E-GEOD-41456 | biostudies-arrayexpress
Project description:RNAseq experiments of Enterovirus A71 wild type demonstrate that the pyrazine-carboxamide ribonucleotide stimulates catalyzed intra- and intermolecular template switching. These results suggest that pyrazine-2 carboxamide ribonucleotides do not induce lethal mutagenesis or chain termination, but function by promoting template switching and formation of defective viral genomes. We conclude that RdRp-catalyzed intra- and intermolecular template switching can be induced by pyrazine-carboxamide ribonucleotides, defining an additional mechanistic class of antiviral ribonucleotides with potential for broad-spectrum activity.
2021-09-14 | GSE183959 | GEO