Project description:Although the cytokine-inducible transcription factors STAT5a/b promote proliferation of a wide range of cell types, there are cell- and context specific cases in which loss of STAT5a/b results in enhanced cell proliferation. Here we report that loss of STAT5a/b from mouse embryonic fibroblasts (MEFs) leads to enhanced proliferation, which was linked to reduced levels of the cell cycle inhibitor p15INK4B and p21CIP1. We further demonstrate that growth hormone through the transcription factor STAT5a/b enhances expression of the cdkn2B gene and that STAT5a binds to GAS sites within the promoter. We have recently demonstrated that ablation of STAT5a/b from liver results in hepatocellular carcinoma upon a CCl4 insult. We also established that in liver tissue, like in MEFs, STAT5a/b activates expression of the cdkn2B gene. Loss of STAT5a/b led to diminished p15INK4B and increased hepatocyte proliferation. This study for the first time demonstrates that cytokines through STAT5a/b can induce the expression of a key cell cycle inhibitor. These experiments therefore shed a light on the context-specific role of STAT5a/b as tumor suppressors. Control and Stat5a/b-null embryonic fibroblasts (MEFs) cells were stimulated w/o a GH including two biological replications per group (Total four groups)
Project description:Although the cytokine-inducible transcription factors STAT5a/b promote proliferation of a wide range of cell types, there are cell- and context specific cases in which loss of STAT5a/b results in enhanced cell proliferation. Here we report that loss of STAT5a/b from mouse embryonic fibroblasts (MEFs) leads to enhanced proliferation, which was linked to reduced levels of the cell cycle inhibitor p15INK4B and p21CIP1. We further demonstrate that growth hormone through the transcription factor STAT5a/b enhances expression of the cdkn2B gene and that STAT5a binds to GAS sites within the promoter. We have recently demonstrated that ablation of STAT5a/b from liver results in hepatocellular carcinoma upon a CCl4 insult. We also established that in liver tissue, like in MEFs, STAT5a/b activates expression of the cdkn2B gene. Loss of STAT5a/b led to diminished p15INK4B and increased hepatocyte proliferation. This study for the first time demonstrates that cytokines through STAT5a/b can induce the expression of a key cell cycle inhibitor. These experiments therefore shed a light on the context-specific role of STAT5a/b as tumor suppressors.
Project description:FOXF1, a member of the forkhead box family of transcription factors, has been previously shown to be critical for lung development, homeostasis, and injury responses. However, the role of FOXF1 in lung regeneration is unknown. Herein, we performed partial pneumonectomy, a model of lung regeneration, in mice lacking one Foxf1 allele in endothelial cells (PDGFb-iCre/Foxf1fl/+ mice). Endothelial cell proliferation was significantly reduced in regenerating lungs from mice deficient for endothelial Foxf1. Decreased endothelial proliferation was associated with delayed lung regeneration as shown by reduced respiratory volume in Foxf1-deficient lungs. FACS-sorted endothelial cells isolated from regenerating PDGFb-iCre/Foxf1fl/+ and control lungs were used for RNAseq analysis to identify FOXF1 target genes. Foxf1 deficiency altered expression of numerous genes including those regulating extracellular matrix remodeling (Timp3, Adamts9) and cell cycle progression (Cdkn1a, Cdkn2b, Cenpj, Tubb4a), which are critical for lung regeneration. Deletion of Foxf1 increased Timp3 mRNA and protein, decreasing MMP14 activity in regenerating lungs. ChIPseq analysis for FOXF1 and histone methylation marks identified DNA regulatory regions with the Cd44, Cdkn1a, and Cdkn2b genes, indicating they are direct FOXF1 targets. Thus FOXF1 stimulates lung regeneration following partial pneumonectomy via direct transcriptional regulation of genes critical for extracellular matrix remodeling and cell cycle progression.
Project description:Cytokines control the biology of hematopoietic stem and progenitor cells in part through the transcription factors STAT5a/b. CCN3/NOV has been reported as a positive regulator of hematopoietic stem and progenitor cells. We report microarray analyses of Lineage- Sca-1+ c-Kit+ (KSL) cells in the presence and absence of STAT5a/b. Expression of the ccn3 gene was induced over 100-fold in control, but not STAT5a/b-null cells, upon stimulation with a cocktail containing IL-3, IL-6, SCF, TPO and Flt3 ligand. Among the cytokines, IL-3 elevated ccn3 mRNA level in Lineage- c-Kit+ (KL) cells and 32D cells. ChIP assays using 32D cells revealed IL-3-induced binding of STAT5a/b to a GAS site in the ccn3 gene promoter. This is the first report to link two molecules with importance in the regulation of HSCs, CCN3 and STAT5a/b. We report that the regulation and expression of the ccn3 gene is directly controlled by IL-3 through the transcription factors STAT5a/b. Six Control and Six Stat5a/b-null KSL cells, including three biological replications, were unstimulated or stimulated with a cocktail containing IL-3, IL-6, SCF, TPO and FL.
Project description:STAT5 interacts with other factors to control transcription, and the mechanism of regulation is of interest as constitutive active STAT5 has been reported in malignancies. Here LSD1 and HDAC3 were identified as novel STAT5a interacting partners in pro-B cells. Characterization of STAT5a, LSD1 and HDAC3 target genes by ChIP-seq and RNA-seq revealed gene subsets regulated by independent or combined action of the factors and LSD1/HDAC3 to play dual role in their activation or repression. Genes bound by STAT5a alone or in combination with weakly associated LSD1 or HDAC3 were enriched for the canonical STAT5a dimer motif, and such binding induced activation or repression. Strong STAT5 binding was seen more frequently in intergenic regions, which might function as distal enhancer elements. Genes bound weakly by STAT5a and strongly by LSD1/HDAC3 present a STAT5a monomer like motif, and are differentially regulated based on their biological role, genomic binding localization and affinity. STAT5a binding in monomer like motifs was found with increased frequency in promoters, indicating a requirement for stabilization by additional factors, which might recruit LSD1/HDAC3. Our study describes an interaction network of STAT5a/LSD1/HDAC3 and a dual function of LSD1/HDAC3 on STAT5-dependent transcription, defined by protein-protein interactions, genomic binding positions-affinities and motifs.
Project description:STAT5 interacts with other factors to control transcription, and the mechanism of regulation is of interest as constitutive active STAT5 has been reported in malignancies. Here LSD1 and HDAC3 were identified as novel STAT5a interacting partners in pro-B cells. Characterization of STAT5a, LSD1 and HDAC3 target genes by ChIP-seq and RNA-seq revealed gene subsets regulated by independent or combined action of the factors and LSD1/HDAC3 to play dual role in their activation or repression. Genes bound by STAT5a alone or in combination with weakly associated LSD1 or HDAC3 were enriched for the canonical STAT5a dimer motif, and such binding induced activation or repression. Strong STAT5 binding was seen more frequently in intergenic regions, which might function as distal enhancer elements. Genes bound weakly by STAT5a and strongly by LSD1/HDAC3 present a STAT5a monomer like motif, and are differentially regulated based on their biological role, genomic binding localization and affinity. STAT5a binding in monomer like motifs was found with increased frequency in promoters, indicating a requirement for stabilization by additional factors, which might recruit LSD1/HDAC3. Our study describes an interaction network of STAT5a/LSD1/HDAC3 and a dual function of LSD1/HDAC3 on STAT5-dependent transcription, defined by protein-protein interactions, genomic binding positions-affinities and motifs.
Project description:Cytokines control the biology of hematopoietic stem and progenitor cells in part through the transcription factors STAT5a/b. CCN3/NOV has been reported as a positive regulator of hematopoietic stem and progenitor cells. We report microarray analyses of Lineage- Sca-1+ c-Kit+ (KSL) cells in the presence and absence of STAT5a/b. Expression of the ccn3 gene was induced over 100-fold in control, but not STAT5a/b-null cells, upon stimulation with a cocktail containing IL-3, IL-6, SCF, TPO and Flt3 ligand. Among the cytokines, IL-3 elevated ccn3 mRNA level in Lineage- c-Kit+ (KL) cells and 32D cells. ChIP assays using 32D cells revealed IL-3-induced binding of STAT5a/b to a GAS site in the ccn3 gene promoter. This is the first report to link two molecules with importance in the regulation of HSCs, CCN3 and STAT5a/b. We report that the regulation and expression of the ccn3 gene is directly controlled by IL-3 through the transcription factors STAT5a/b.
Project description:IL-17A and F are critical cytokines in anti-microbial immunity but also contribute to auto-immune pathologies. Recent evidence suggests that they may be differentially produced by T-helper (Th) cells but the underlying mechanisms remain unknown. To address this question, a logical model containing 82 components and 136 regulatory links was developed and calibrated with original flow cytometry data using naive CD4+ T cells in conditions inducing either IL-17A or F. Model analyses led to the identification of the transcription factors NFAT2A, STAT5A and Smad2 as key components explaining the differential expression of IL-17A and IL-17F, with STAT5A controlling IL-17F expression, and an interplay of NFAT2A, STAT5A and Smad2 controlling IL-17A expression.
Project description:MAF1 represses Pol III-mediated transcription by interfering with TFIIIB and Pol III. Herein, we found that MAF1 knockdown induced CDKN1A transcription and chromatin looping concurrently with Pol III recruitment. Simultaneous knockdown of MAF1 with Pol III or BRF1 (subunit of TFIIIB) diminished the activation and looping effect, which indicates that recruiting Pol III was required for activation of Pol II-mediated transcription and chromatin looping. ChIP analysis after MAF1 knockdown indicated enhanced binding of Pol III and BRF1, as well as of CFP1, p300, and PCAF, which are factors that mediate active histone marks, along with the binding of TBP and POLR2E to the CDKN1A promoter. Simultaneous knockdown with Pol III abolished these regulatory events. Similar results were obtained for GDF15. Our results reveal a novel mechanism by which MAF1 and Pol III regulate the activity of a protein-coding gene transcribed by Pol II.