Identification of a new PPARG isoform
Ontology highlight
ABSTRACT:
PROVIDER: PRJEB28823 | ENA |
REPOSITORIES: ENA
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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.
2018-10-14 | GSE120466 | GEO
Project description:Peroxisome proliferator-activated receptor g (PPARg) is a nuclear receptor that is a vital regulator of adipogenesis, insulin sensitivity, and lipid metabolism. Activation of PPARg by antidiabetic thiazolidinediones (TZD) reverses insulin resistance but also leads to weight gain that limits the use of these drugs. There are two main PPARg isoforms, but the specific functions of each are not established. Here we generated mouse lines in which endogenous PPARg1 and PPARg2 were epitope-tagged to interrogate isoform-specific genomic binding, and mice deficient in either PPARg1 or PPARg2 to assess isoform-specific gene regulation. Strikingly, although PPARg1 and PPARg2 contain identical DNA binding domains, we uncovered isoform-specific genomic binding sites in addition to shared sites. Moreover, PPARg1 and PPARg2 regulated different set of genes in adipose tissue depots, suggesting distinct roles in adipocyte biology. Indeed, mice with selective deficiency of PPARg1 maintained body temperature better than wild type or PPARg2-deficient mice. Most remarkably, although TZD treatment improved glucose toleranceinsulin resistance in mice lacking either PPARg1 or PPARg2, the PPARg1-deficient mice were protected from TZD-induced body weight gain compared to PPARg2-deficient mice. Thus, PPARg isoforms have specific and separable metabolic functions that may be targeted to improve therapy for insulin resistance and diabetes.
2022-03-25 | GSE186277 | GEO
Project description:Background: The beneficial effect of thermogenic adipocytes in maintaining body weight and protecting against metabolic disorders has raised interest in understanding the regulatory mechanisms defining white and beige adipocyte identity. Although alternative splicing has been shown to propagate adipose browning signals in mice, this has yet to be thoroughly investigated in human adipocytes. Methods: We performed parallel white and beige adipogenic differentiation using primary adipose stem cells from 6 unrelated healthy subjects, and assessed differential gene and isoform expression in mature adipocytes by RNA sequencing. Results: We find 693 exon junctions with robust differential usage between white and beige adipocytes in all 6 subjects, mapping to 507 genes. Importantly, only 8% of these differentially spliced genes are also differentially expressed, indicating that alternative splicing constitutes an additional layer of gene expression regulation during beige adipocyte adipogenic differentiation. Functional classification of alternative isoforms point to a gain of function for key thermogenic regulators such as PPARG, CITED1 and PEMT. We find that a large majority of the splice variants arise from differential usage of transcription start sites (TSSs), with beige-specific TSSs being enriched for PPARγ and MED1 binding compared to white-specific TSSs. Finally, we validate beige specific isoform expression at the protein level for two thermogenic regulators, PPARγ and PEMT. Discussion: These results indicate that differential isoform expression through alternative TSS usage is an important regulatory mechanism for human adipocyte thermogenic specification.
2024-05-14 | GSE256260 | GEO
Project description:Background: The beneficial effect of thermogenic adipocytes in maintaining body weight and protecting against metabolic disorders has raised interest in understanding the regulatory mechanisms defining white and beige adipocyte identity. Although alternative splicing has been shown to propagate adipose browning signals in mice, this has yet to be thoroughly investigated in human adipocytes. Methods: We performed parallel white and beige adipogenic differentiation using primary adipose stem cells from 6 unrelated healthy subjects, and assessed differential gene and isoform expression in mature adipocytes by RNA sequencing. Results: We find 693 exon junctions with robust differential usage between white and beige adipocytes in all 6 subjects, mapping to 507 genes. Importantly, only 8% of these differentially spliced genes are also differentially expressed, indicating that alternative splicing constitutes an additional layer of gene expression regulation during beige adipocyte adipogenic differentiation. Functional classification of alternative isoforms point to a gain of function for key thermogenic regulators such as PPARG, CITED1 and PEMT. We find that a large majority of the splice variants arise from differential usage of transcription start sites (TSSs), with beige-specific TSSs being enriched for PPARγ and MED1 binding compared to white-specific TSSs. Finally, we validate beige specific isoform expression at the protein level for two thermogenic regulators, PPARγ and PEMT. Discussion: These results indicate that differential isoform expression through alternative TSS usage is an important regulatory mechanism for human adipocyte thermogenic specification. Code for data processing and analysis are available at https://github.com/sarahhp/splicing_thermogenesis.
2024-05-14 | GSE256259 | GEO
Project description:Ligand-mediated activation of the nuclear hormone receptor PPAR gamma lowers blood pressure and improves glucose tolerance in humans. Two naturally occurring mutations (P467L, V290M) in the ligand binding domain of PPAR gamma have been described in humans that lead to severe insulin resistance and hypertension. Experimental evidence suggests that these mutant versions of PPAR gamma act in a dominant negative fashion. To better understand the molecular mechanisms underlying PPAR gamma action in the vasculature, we determined the global gene expression profile in primary aortic endothelial cells in response to endothelial cell specific expression of a dominant negative isoform of PPAR gamma (V290M).
2008-07-23 | GSE11870 | GEO
Project description:The generation of distiThe generation of distinct messenger RNA isoforms through alternative RNA processing influences the expression and function of genes, often in a cell-type specific manner. Here, we assess the regulatory relationships between transcription initiation, alternative splicing, and 3ʹ end site selection. Applying multiple long-read-sequencing approaches to obtain an assembly accurately representing even the longest transcripts from end to end, we quantify mRNA isoform choice in Drosophila and human tissues, including the transcriptionally complex nervous system. We find that in Drosophila brains as well as in human cerebral organoids, 3ʹ end site choice is globally influenced by the site of transcription initiation. “Dominant promoters”, characterized by specific epigenetic signatures including p300/CBP binding, impose a transcriptional constraint to define splice and polyadenylation variants. In vivo deletion or overexpression of dominant promoters as well as CBP/p300 loss disrupted the 3ʹ end expression landscape. Our study demonstrates the crucial impact of TSS choice on the regulation of transcript diversity and tissue identity.ct messenger RNA isoforms through alternative splicing and alternative 3' end formation influences the expression and function of genes, often in a cell-type specific manner. Here, we quantitatively assess the regulatory relationships between transcription initiation and co-transcriptional processing steps, particularly 3' end formation. Applying multiple long-read-sequencing approaches to obtain an assembly accurately representing even the longest mRNA isoforms from end-to-end, we quantify mRNA isoform choice in Drosophila and human tissues, including the transcriptionally complex nervous system. We find that in Drosophila brains as well as in human cerebral organoids, 3' end site choice is globally influenced by the site of transcription start. We define a subset of TSSs, “dominant promoters” that impose a transcriptional constraint to predetermine splice and polyadenylation variants, which are characterized by specific epigenetic signatures. In vivo deletion or overexpression of dominant promoters disrupted the 3' end expression landscape. Our study demonstrates the crucial impact of transcription initiation site choice on the regulation of transcript diversity and tissue identity.
2023-05-10 | GSE221324 | GEO
Project description:The generation of distinct messenger RNA isoforms through alternative RNA processing influences the expression and function of genes, often in a cell-type specific manner. Here, we assess the regulatory relationships between transcription initiation, alternative splicing, and 3ʹ end site selection. Applying multiple long-read-sequencing approaches to obtain an assembly accurately representing even the longest transcripts from end to end, we quantify mRNA isoform choice in Drosophila and human tissues, including the transcriptionally complex nervous system. We find that in Drosophila brains as well as in human cerebral organoids, 3ʹ end site choice is globally influenced by the site of transcription initiation. “Dominant promoters”, characterized by specific epigenetic signatures including p300/CBP binding, impose a transcriptional constraint to define splice and polyadenylation variants. In vivo deletion or overexpression of dominant promoters as well as CBP/p300 loss disrupted the 3ʹ end expression landscape. Our study demonstrates the crucial impact of TSS choice on the regulation of transcript diversity and tissue identity.ct messenger RNA isoforms through alternative splicing and alternative 3' end formation influences the expression and function of genes, often in a cell-type specific manner. Here, we quantitatively assess the regulatory relationships between transcription initiation and co-transcriptional processing steps, particularly 3' end formation. Applying multiple long-read-sequencing approaches to obtain an assembly accurately representing even the longest mRNA isoforms from end-to-end, we quantify mRNA isoform choice in Drosophila and human tissues, including the transcriptionally complex nervous system. We find that in Drosophila brains as well as in human cerebral organoids, 3' end site choice is globally influenced by the site of transcription start. We define a subset of TSSs, “dominant promoters” that impose a transcriptional constraint to predetermine splice and polyadenylation variants, which are characterized by specific epigenetic signatures. In vivo deletion or overexpression of dominant promoters disrupted the 3' end expression landscape. Our study demonstrates the crucial impact of transcription initiation site choice on the regulation of transcript diversity and tissue identity.
2023-05-10 | GSE221323 | GEO
Project description:Alternative RNA splicing can generate distinct protein isoforms to allow for the differential control of cell processes across cell types. The chromosome segregation and cell division programs associated with somatic mitosis and germline meiosis display dramatic differences such as kinetochore orientation, cohesin removal, or the presence of a gap phase. These changes in chromosome segregation require alterations to the established cell division machinery. However, it remains unclear what aspects of kinetochore function and its regulatory control differ between the mitotic and meiotic cell divisions to rewire these core processes. Additionally, the alternative splice isoforms that differentially modulate distinct cell division programs have remained elusive. Here, we demonstrate that mammalian germ cells express an alternative mRNA splice isoform for the kinetochore component, DSN1, a subunit of the MIS12 complex that links the centromeres to spindle microtubules during chromosome segregation. This germline DSN1 isoform bypasses the requirement for Aurora kinase phosphorylation for its centromere localization due to the absence of a key regulatory region allowing DSN1 to display persistent centromere localization. Expression of the germline DSN1 isoform in somatic cells results in constitutive kinetochore localization, chromosome segregation errors, and growth defects, providing an explanation for its tight cell type-specific expression. Reciprocally, precisely eliminating expression of the germline-specific DSN1 splice isoform in mouse models disrupts oocyte maturation and early embryonic divisions coupled with a reduction in fertility. Together, this work identifies a germline-specific splice isoform for a chromosome segregation component and implicates its role in mammalian fertility.
2024-08-28 | PXD054119 | Pride
Project description:The naturally occurring ∆40p53 isoform inhibits eRNA transcription and enables context-specific regulatory inputs during p53 activation.
| PRJNA616140 | ENA
Project description:Peroxisome proliferator–activated receptor γ (PPARγ) is the central regulator of adipogenesis, and its dysregulation is linked to obesity and metabolic diseases. Identification of the factors that regulate PPARγ expression and activity is therefore crucial for combating obesity. Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor with a known role in xenobiotic detoxification. Recent studies have suggested that AhR also plays essential roles in energy metabolism. However, the detailed mechanisms remain unclear. We previously reported that experiments with adipocyte-specific Cullin 4b (Cul4b)-knockout mice showed that CUL4B suppresses adipogenesis by targeting PPARγ. Here, using immunoprecipitation, ubiquitination, real-time PCR and Gst-pulldown assays, we report that AhR functions as the substrate receptor in CUL4B–RING E3 ubiquitin ligase (CRL4B) complex and is required for recruiting PPARγ. AhR overexpression reduced PPARγ stability and suppressed adipocyte differentiation, and AhR knockdown stimulated adipocyte differentiation in 3T3-L1 cells. Furthermore, we found that two lysine sites on residues 268 and 293 in PPARγ are targeted for CRL4B-mediated ubiquitination, indicating cross-talk between acetylation and ubiquitination. Our findings establish a critical role of AhR in regulating PPARγ stability and suggest that the AhR–PPARγ interaction may represent a potential therapeutic target for managing metabolic diseases arising from PPARγ dysfunction.
2019-11-01 | PXD015830 | Pride