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Project description:Hypoxia Inducible Factor (HIF) regulates a cascade of transcriptional events in response to decreased oxygenation, acting from the cellular to the physiological level. This response is evolutionarily conserved, allowing the use of zebrafish (Danio rerio) as a model for studying the hypoxic response. Activation of the hypoxic response can be achieved in zebrafish by homozygous null mutation of the von Hippel-Lindau (vhl) tumour suppressor gene. Previous work from our lab has focused on the phenotypic characterisation of this mutant, establishing the links between vhl mutation, the hypoxic response and cancer. To further develop fish as a model for studying hypoxic signalling, we examine the transcriptional profile of the vhl mutant with respect to Hif-1?. As our approach uses embryos consisting of many cell types, it has the potential to uncover additional HIF regulated genes that have escaped detection in analogous mammalian cell culture studies.We performed high-density oligonucleotide microarray analysis of the gene expression changes in von Hippel-Lindau mutant zebrafish, which identified up-regulation of well-known hypoxia response genes and down-regulation of genes primarily involved in lipid processing. To identify the dependency of these transcriptional changes on HIF, we undertook Chromatin Immunoprecipitation linked next generation sequencing (ChIP-seq) for the transcription factor Hypoxia Inducible Factor 1? (HIF-1?). We identified HIF-1? binding sites across the genome, with binding sites showing enrichment for an RCGTG motif, showing conservation with the mammalian hypoxia response element.Transcriptome analysis of vhl mutant embryos detected activation of key hypoxia response genes seen in human cell models of hypoxia, but also suppression of many genes primarily involved in lipid processing. ChIP-seq analysis of Hif-1? binding sites unveiled an unprecedented number of loci, with a high proportion containing a canonical hypoxia response element. Whether these sites are functional remains unknown, nevertheless their frequent location near transcriptional start sites suggests functionality, and will allow for investigation into the potential hypoxic regulation of genes in their vicinity. We expect that our data will be an excellent starting point for analysis of both fish and mammalian gene regulation by HIF.
| S-EPMC4642629 | biostudies-literature
Project description:BackgroundGenome-wide maps of transcription factor binding sites in primary tissues can expand our understanding of genome function, transcriptional regulation, and genetic alterations that contribute to disease risk. However, almost all genome-wide studies of transcription factors have been in cell lines, and performing these experiments in tissues has been technically challenging and limited in throughput.ResultsHere we outline a simple strategy for mapping transcription factor binding sites in frozen tissues that utilizes dry pulverization of samples and is scalable for high-throughput analyses. We show that the method leads to accurate and reproducible chromatin immunoprecipitation next-generation sequencing (ChIP-seq) data, and is highly sensitive, identifying high-quality transcription factor binding sites from chromatin corresponding to only 5 mg of liver tissue.ConclusionsThe enhanced reproducibility, robustness, and sensitivity of the dry pulverization method, in addition to the ease of implementation and scalability, makes ChIP-seq in primary tissues a widely accessible assay.
| S-EPMC3848595 | biostudies-literature
Project description:The Forkhead box O (Foxo) family of transcription factors has a critical role in controlling the development, differentiation, and function of T cells. However, the direct target genes of Foxo transcription factors in T cells have not been well characterized. In this study, we focused on mapping the genome wide Foxo1-binding sites in naïve CD4+ T cells, CD8+ T cells, and Foxp3+ regulatory T (Treg) cells. By using chromatin immunoprecipitation coupled with deep sequencing (ChIP-Seq), we identified Foxo1 binding sites that were shared among or specific to the three T cell populations. Here we describe the experiments, quality controls, as well as the deep sequencing data. Part of the data analysis has been published by Ouyang W et al. in Nature 2012[1] and Kim MV et al. in Immunity 2013[2], and the associated data set were uploaded to NCBI Gene Expression Omnibus.
| S-EPMC4185926 | biostudies-literature
Project description:Hnf4a is specifically expressed in developing proximal tubule cells in the newborn mouse kidney. In order to identify direct target genes of Hnf4a in the developing proximal tubules, we performed ChIP-Seq of Hnf4a in the mouse kidneys at P0.
2020-11-12 | GSE144824 | GEO
Project description:Genetic alterations in the transcriptional repressor ETV6 are associated with hematological malignancies. Notably, the t(12;21) translocation leading to an ETV6-AML1 fusion gene is the most common genetic alteration found in childhood acute lymphoblastic leukemia. Moreover, most of these patients also lack ETV6 expression, suggesting a tumor suppressor function. To gain insights on ETV6 DNA-binding specificity and genome wide transcriptional regulation capacities, we performed chromatin immunoprecipitation experiments coupled to deep sequencing in a t(12;21)-positive pre-B leukemic cell line. This strategy led to the identification of ETV6-bound regions that were further associated to gene expression. ETV6 binding is mostly cell type-specific as only few regions are shared with other blood cell subtypes. Peaks localization and motif enrichment analyses revealed that this unique binding profile could be associated with the ETV6-AML1 fusion protein specific to the t(12;21) background. This study underscores the complexity of ETV6 binding and uncovers ETV6 transcriptional network in pre-B leukemia cells bearing the recurrent t(12;21) translocation.
| S-EPMC6195514 | biostudies-literature
Project description:Hypoxia-inducible factor (HIF) regulates the major transcriptional cascade central to the response of all mammalian cells to alterations in oxygen tension. Expression arrays indicate that many hundreds of genes are regulated by this pathway, controlling diverse processes that in turn orchestrate both oxygen delivery and utilization. However, the extent to which HIF exerts direct versus indirect control over gene expression together with the factors dictating the range of HIF-regulated genes remains unclear. Using chromatin immunoprecipitation linked to high throughput sequencing, we identify HIF-binding sites across the genome, independently of gene architecture. Using gene set enrichment analysis, we demonstrate robust associations with the regulation of gene expression by HIF, indicating that these sites operate over long genomic intervals. Analysis of HIF-binding motifs demonstrates sequence preferences outside of the core RCGTG-binding motif but does not reveal any additional absolute sequence requirements. Across the entire genome, only a small proportion of these potential binding sites are bound by HIF, although occupancy of potential sites was enhanced approximately 20-fold at normoxic DNAse1 hypersensitivity sites (irrespective of distance from promoters), suggesting that epigenetic regulation of chromatin may have an important role in defining the response to hypoxia.
| S-EPMC3374576 | biostudies-literature
Project description:Alternative splicing is regulated by splicing factors that serve as positive or negative effectors, interacting with regulatory elements along exons and introns. Here we present a novel computational method for genome-wide mapping of splicing factor binding sites that considers both the genomic environment and the evolutionary conservation of the regulatory elements. The method was applied to study the regulation of different alternative splicing events, uncovering an interesting network of interactions among splicing factors.
| S-EPMC2691001 | biostudies-literature
Project description:Collier, the single Drosophila COE (Collier/EBF/Olf-1) transcription factor, is required in several developmental processes, including head patterning and specification of muscle and neuron identity during embryogenesis. To identify direct Collier (Col) targets in different cell types, we used ChIP-seq to map Col binding sites throughout the genome, at mid-embryogenesis. In vivo Col binding peaks were associated to 415 potential direct target genes. Gene Ontology analysis revealed a strong enrichment in proteins with DNA binding and/or transcription-regulatory properties. Characterization of a selection of candidates, using transgenic CRM-reporter assays, identified direct Col targets in dorso-lateral somatic muscles and specific neuron types in the central nervous system. These data brought new evidence that Col direct control of the expression of the transcription regulators apterous and eyes-absent (eya) is critical to specifying neuronal identities. They also showed that cross-regulation between col and eya in muscle progenitor cells is required for specification of muscle identity, revealing a new parallel between the myogenic regulatory networks operating in Drosophila and vertebrates. Col regulation of eya, both in specific muscle and neuronal lineages, may illustrate one mechanism behind the evolutionary diversification of Col biological roles.
2015-08-03 | GSE67805 | GEO
Project description:We firstly found that DsbRS TCS (encoded by PA2479-PA2480) was involved in counteracting the toxic effects of copper. The identification of two DsbR binding reigions in dsbD-dsbR intergenic region DNA led us to globally characterize all DsbR-binding loci on the chromosome of Pseudomonas aeruginosa. In order to express C-terminal flag-tagged DsbR, we first constructed the ΔdsbRS::DsbR-Flag strain. We next investigated DsbR-binding to the chromosome of this strain during exponential growth by ChIP-Seq, chromatin immunoprecipitation followed by ultra-high throughput DNA sequencing. Sequence reads obtained from three independent ChIP-Seq experiments using Flag-specific antibodies were mapped to the genome of the ΔdsbRS::DsbR-Flag strain. Using MACS software, we identified 18 reproducible peaks of DsbR binding, which were enriched by >2 fold.Approximately 83% (15 peaks) are in the promoter regions of 23 genes (within 600 bp upstream of the translational start site) involved or potentially involved in various biological processes including protein folding (e.g., dsbDEG operon and dsbB), protein secretion (e.g.., hxcU, hxcP, hcpC), transport (e.g., opdT, pa2911, and pstS), and regulation of transcription (i.e., dsbRS, pa3398). Collectively, this study thus uncover a new signal transduction pathway in P. aeruginosa, DsbS/DsbR/DsbDEG and DsbB, for the regulation of Dsb system in response to copper stress.
2020-07-12 | GSE154248 | GEO
Project description:There are nearly fifty forkhead (FOX) transcription factors encoded in the human genome and due to sharing a common DNA binding domain, they are all thought to bind to similar DNA sequences. It is therefore unclear how these transcription factors are targeted to specific chromatin regions to elicit specific biological effects. Here we used ChIP-seq to investigate the genome-wide chromatin binding mechanisms used by the forkhead transcription factor FOXM1. In keeping with its previous association with cell cycle control, we demonstrate that FOXM1 binds and regulates a group of genes which are mainly involved in controlling late cell cycle events in the G2 and M phases. However, rather than being recruited through canonical RYAAAYA forkhead binding motifs, FOXM1 binding is directed via CHR elements. FOXM1 binds these elements through protein-protein interactions with the MMB transcriptional activator complex. Thus, we have uncovered a novel and unexpected mode of chromatin binding of a FOX transcription factor which allows it to specifically control cell cycle-dependent gene expression.
2012-11-05 | GSE38170 | GEO