E2F1 ChIP-Seq on mouse hepatocytes overexpressing E2F1
Ontology highlight
ABSTRACT: E2F transcription factors are known regulators of the cell cycle, proliferation, apoptosis and differentiation. We reveal an essential role for E2F1 in liver through the regulation of glycolysis and lipogenesis. E2F1 deficiency leads to a decreased in glycolysis and de novo synthesis of fatty acids in hepatocytes. ChIP-Seq was performed to determine direct tagets of E2F1 in hepatocytes. We highlight that E2F1 directly binds the promoters of genes implicated in metabolic process and notably key lipogenic genes to control these pathways.
Project description:The specific ablation of Rb1 gene in epidermis (RbF/F;K14cre) promotes proliferation and altered differentiation but does not produce spontaneous tumour development. These phenotypic changes are associated with increased expression of E2F members and E2F-dependent transcriptional activity. Here, we have focused on the possible dependence on E2F1 gene function. We have generated mice that lack Rb1 in epidermis in an inducible manner (RbF/F;K14creERTM). These mice are indistinguishable from those lacking pRb in this tissue in a constitutive manner (RbF/F;K14cre). In an E2F1-null background (RbF/F;K14creERTM; E2F1-/- mice), the phenotype due to acute Rb1 loss is not ameliorated by E2F1 loss, but rather exacerbated, indicating that pRb functions in epidermis do not rely solely on E2F1. On the other hand, RbF/F;K14creERTM;E2F1-/- mice develope spontaneous epidermal tumours of hair follicle origin with high incidence. These tumours, which retain a functional p19arf/p53 axis, also show aberrant activation of βcatenin/Wnt pathway. Gene expression studies revealed that these tumours display relevant similarities with specific human tumours. These data demonstrate that the Rb/E2F1 axis exerts essential functions not only in maintaining epidermal homeostasis, but also in suppressing tumour development in epidermis, and that the disruption of this pathway may induce tumour progression through specific alteration of developmental programs. Gene expression was compared between normal mouse skin, skin from transgenic RbF/F;K14creERTM; E2F1-/- , E2F1-/-, and RbF/F;K14creERTM; E2F1-/- mouse, and carcinomas arising in the skin of RbF/F;K14creERTM; E2F1-/- mouse. All mice were treated with tamoxifen.
Project description:Fat accumulation, de novo lipogenesis, and glycolysis are key contributors to hepatocyte reprogramming and the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD). The molecular mechanisms affected by steatosis and inflammation in the obese states remain unknown. Here we report that obesity leads to dysregulated expression of protein-tyrosine phosphatases (PTPs) in the liver. Protein Tyrosine Phosphatase Receptor Kappa (PTPRK) was increased in hepatocytes by steatosis and inflammation in humans and mice, and positively correlates with PPARγ-induced lipogenic signalling. Mechanistically, PTPRK-PPARγ upregulation by fat accumulation is dependent upon Notch signalling in mouse primary hepatocytes. PTPRK knockout mice have reduced fat accumulation in adipose tissue and liver after exposure to an obesogenic diet. Phosphoproteomic analysis in isolated hepatocytes and hepatic metabolomics identified specific phosphotyrosine residues in fructose-1,6 bisphosphatase-1 and glycolysis regulation as targets of PTPRK. These changes in glycolysis and de novo lipogenesis revealed PTPRK-dependent metabolic reprogramming in hepatocytes. Moreover, hepatoma cell lines showed reduced colony-forming ability after PTPRK silencing in vitro, and PTPRK knockout mice developed smaller tumours after diethylnitrosamine-induced hepatocarcinogenesis in vivo. Computational modelling identified potential PTPRK inhibitors, which selectively reduced PTPRK activity. The compounds decreased glycolytic rates in hepatoma cell lines, PPARγ expression in primary hepatocytes and steatosis in obese mice. In conclusion, our study defines a novel mechanism for the development of MASLD, revealing a key role of PTPRK on hepatic glycolysis regulation with implications in lipid metabolism, and liver tumour development. We propose PTPRK as a potential target for metabolic liver dysfunction, and the identified inhibitors may represent promising candidates for therapy in obesity-associated liver diseases.
Project description:The specific ablation of Rb1 gene in epidermis (RbF/F;K14cre) promotes proliferation and altered differentiation but does not produce spontaneous tumour development. These phenotypic changes are associated with increased expression of E2F members and E2F-dependent transcriptional activity. Here, we have focused on the possible dependence on E2F1 gene function. We have generated mice that lack Rb1 in epidermis in an inducible manner (RbF/F;K14creERTM). These mice are indistinguishable from those lacking pRb in this tissue in a constitutive manner (RbF/F;K14cre). In an E2F1-null background (RbF/F;K14creERTM; E2F1-/- mice), the phenotype due to acute Rb1 loss is not ameliorated by E2F1 loss, but rather exacerbated, indicating that pRb functions in epidermis do not rely solely on E2F1. On the other hand, RbF/F;K14creERTM;E2F1-/- mice develope spontaneous epidermal tumours of hair follicle origin with high incidence. These tumours, which retain a functional p19arf/p53 axis, also show aberrant activation of βcatenin/Wnt pathway. Gene expression studies revealed that these tumours display relevant similarities with specific human tumours. These data demonstrate that the Rb/E2F1 axis exerts essential functions not only in maintaining epidermal homeostasis, but also in suppressing tumour development in epidermis, and that the disruption of this pathway may induce tumour progression through specific alteration of developmental programs.
Project description:The E2F family consists of transcriptional repressors and activators that control cell proliferation. In the classic paradigm of cell cycle regulation, the three activators, E2F1, E2F2 and E2F3, are invariably depicted as the final components of a CDK/Rb signaling cascade that executes the transcriptional program necessary to commit cells to enter S phase. Unexpectedly, we find through analysis of Affymetrix expression array data that mature lens epithelial cells deficient for E2F1-3 fail to repress cell cycle-regulated genes (and other targets of E2F) and that this corresponds with subsequent apoptosis and cellular collapse in the lens. Murine lenses were collected at two stages of development for RNA extraction and hybridization on Affymetrix microarrays. Our aim was to determine key events that lead to cellular collapse of lenses triply deficient for E2F1, E2F2, and E2F3 in neonates.
Project description:The E2F family consists of transcriptional repressors and activators that control cell proliferation. In the classic paradigm of cell cycle regulation, the three activators, E2F1, E2F2 and E2F3, are invariably depicted as the final components of a CDK/Rb signaling cascade that executes the transcriptional program necessary to commit cells to enter S phase. Unexpectedly, we find through analysis of Affymetrix expression array data that mature lens epithelial cells deficient for E2F1-3 fail to repress cell cycle-regulated genes (and other targets of E2F) and that this corresponds with subsequent apoptosis and cellular collapse in the lens.
Project description:E2F transcriptional activators and repressors regulate cell cycle-dependent gene expression. Using a series of E2f loss- and gain-of-function mice we show that development is relatively insensitive to alterations in individual E2F levels and composition. However, modest increases in E2F transcriptional output (E2f7Δ/Δ;E2f8Δ/Δ, E2f1KI/1KI and E2f3bKI/3bKI) resulted in spontaneous hepatocellular carcinoma (HCC) without additional organ involvement, whereas decreases (E2f1-/- and E2f3b-/-) protected against HCC. DNA binding domain-, cell type- and temporal-specific gene ablation strategies defined a cell autonomous oncogenic role for E2F1/3B and a tumor suppressor role for E2F8 in hepatocytes during early post-natal liver development. Chromatin binding and expression profiling revealed a mechanism involving activation by E2F1/3B and repression by E2F7/8 to antagonistically regulate a common set of target genes associated with HCC progression. Thus, while development is sufficiently robust to withstand changes in E2F composition and activity, the liver is uniquely sensitive to perturbations in E2Fs. In summary, precise E2F transcriptional output in hepatocytes during early adolescence is critical to foster a cancer-free life span.
Project description:SRY-Box Transcription Factor 17 (SOX17) enhancers variants and mutations are found in patients with pulmonary arterial hypertension (PAH). In human PAH pulmonary microvascular endothelial cells (HPMVEC), there is a significant downregulation of SOX17 expression. We hypothesized that SOX17 deficiency contributes to the pathogenesis of PAH and found that mice with endothelial specific disruption (ecKO Sox17) developed spontaneous pulmonary hypertension (PH) and exacerbated hypoxia-induced PH. Loss of SOX17 in lung ECs induces cell cycle programming, proliferative and anti-apoptotic phenotypes, a process mediated by the activation of E2F Transcription Factor 1 (E2F1) signaling. Pharmacological inhibition of E2F1 in ecKO Sox17 mice attenuated PH and cell cycle programming. Our study demonstrated that endothelial SOX17 deficiency induces PH and targeting E2F1 signaling represents a promising approach in PAH patients.
Project description:SRY-Box Transcription Factor 17 (SOX17) enhancers variants and mutations are found in patients with pulmonary arterial hypertension (PAH). In human PAH pulmonary endothelial cells, there is a significant downregulation of SOX17 expression. We hypothesized that SOX17 deficiency contributes to the pathogenesis of PAH and found that mice with endothelial specific disruption (ecKO Sox17) developed spontaneous pulmonary hypertension (PH) and exacerbated hypoxia-induced PH. Loss of SOX17 in lung ECs induced endothelial dysfunctions including upregulation of cell cycle programming and paracrine effect, proliferative and anti-apoptotic phenotypes, impaired cellular junction and BMP signaling. E2F Transcription Factor 1 (E2F1) signaling was showed to mediate the SOX17 deficiency-induced EC dysfunction. Pharmacological inhibition of E2F1 in ecKO Sox17 mice attenuated PH and cell cycle programming. Our study demonstrated that endothelial SOX17 deficiency induces PH through E2F1 and targeting E2F1 signaling represents a promising approach in PAH patients.
Project description:Metabolic dysfunction within the liver is a major cause of human disease worldwide. Fat accumulation, de novo lipogenesis, and glycolysis are key drivers of hepatocyte reprogramming and the consequent metabolic dysfunction-associated steatotic liver disease (MASLD). The underpinning molecular mechanisms affected by steatosis and inflammation in the obese states remain unknown. Here we report that obesity leads to dysregulated expression of protein-tyrosine phosphatases (PTPs) in the liver. Protein Tyrosine Phosphatase Receptor Kappa (PTPRK) expression was increased in hepatocytes during steatosis and inflammation in humans and mice, and positively correlates with PPARγ-induced lipogenic signalling. Supporting this, PTPRK knockout mice displayed reduced fat accumulation in adipose tissue and liver after exposure to an obesogenic diet. Phosphoproteomic analysis in primary hepatocytes and hepatic metabolomics identified specific phosphotyrosine residues in fructose-1,6 bisphosphatase-1 and glycolysis regulation as targets of PTPRK. The changes in glycolysis and de novo lipogenesis revealed PTPRK was a driving force for metabolic reprogramming in hepatocytes. Moreover, hepatoma cell lines showed reduced colony-forming ability after PTPRK silencing in vitro, and PTPRK knockout mice developed smaller tumours after diethylnitrosamine-induced hepatocarcinogenesis in vivo. Through computational modelling, we identified selective PTPRK inhibitors. These compounds decreased glycolytic rates in hepatoma cell lines, PPARγ expression in primary hepatocytes and steatosis in obese mice. In conclusion, our study defines a novel mechanism for the development of MASLD, revealing a key role of PTPRK on hepatic glycolysis regulation with implications in lipid metabolism, and liver tumour development. We propose PTPRK as a potential target for metabolic liver dysfunction, and the identified inhibitors may represent promising candidates for therapy in obesity-associated liver diseases.
Project description:Overexpression of miR-183-5p|+2, but not of the other two isomiRs |0 and |+1, was observed to reduce cell cycle and cell proliferation in different triple-negative breast cancer cell lines. Therefore, we hypothesized that the |+2 isoform has targets distinct from the other two isoforms. To test this hypothesis, we overexpressed separately the three different isoforms or negative controls (siAllstar or mimic-Cltr) and performed Mass Spectrometry to identify differentially regulated proteins. Interestingly, a gene set enrichment analysis of the changes in protein expression revealed significant downregulation of transcriptional targets of E2F specifically in cells transfected with the |+2 isoform prompting us to validate the predicted isomiR specific target E2F1. Subsequently, we could show that direct targeting of E2F1 by miR-183-5p|+2 is responsible for the impact of the isomiR on cell cycle and proliferation.