Project description:Developmental programs are implemented by regulatory interactions between Transcription Factors (TFs) and their target genes, which remain yet poorly understood. While recent studies have focused on regulatory cascades of TFs that govern early development, little is known on how these are selected and controlled the ultimate cellular effectors of terminal differentiation. We addressed this question during late Drosophila embryogenesis when the finely tuned expression of a TF, Ovo/Shavenbaby (Svb), triggers the morphological differentiation of epidermal trichomes. We used chromatin immunoprecipitation and microarray profiling to identify Svb downstream target genes and show that Svb directly regulates a large set of terminal effectors of trichome formation. Functional assays delineated 18 Svb bound sequences driving specific expression of trichome effectors, with highly similar pattern and dynamics. Coupling computational modeling to functional dissection, we further investigated the regulatory logic of these enhancers. We find that these “terminal” enhancers harbor remarkable features with respect to their functional architectures. Trichome enhancers display weak if any clustering of Svb binding sites. Moreover, the in vivo function of each site relies on its intimate context, with a critical importance of the nucleotides flanking Svb binding sites. Finally, we identify additional cis-regulatory motifs, showing a broad diversity of positioning among trichome enhancers, and that critically contribute to their activity. Taken together, these results show that trichome formation is underpinned by unexpectedly diverse modes of regulation, and shed light on the functional architecture of enhancers governing a terminal differentiation program. Chromatin from 12-14 hour old embryos expressing svb tagged with GFP (Kondo T, Plaza S, Zanet J, Benrabah E, Valenti P, Hashimoto Y, Kobayashi S, Payre F, Kageyama Y: Small peptides switch the transcriptional activity of Shavenbaby during Drosophila embryogenesis. Science 2010, 329:336-339) was collected in duplicate. Chromatin was immunoprecipitated using an antiGFP antibody and input chromatin was used as a control.
Project description:This study aimed to further understand context-specific direct Wnt target gene expression through the use of beta-catenin and FoxH1 ChIP Sequencing data at various developmental stages representing both maternal and zygotic Wnt signalling. Results were further supported through the use of RNA sequencing data from beta-catenin, FoxH1 and nodal gene knock down assays.
Project description:Polycomb-mediated gene repression plays an important role in adult stem cell maintenance. Direct targets of the Polycomb repressive complex PRC2 in th intestinal epithelium were revealed by performing ChIP-sequencing on crypt samples isolated from wild type murine small intestines. The resulting list of H3K27me3-enriched genes were compared with RNA-sequencing data from wild type and Eed knockout crypts. Crypts were isolated from wild type murine intestinal epithelium and subjected to ChIP using anti-H3K27me3 and anti-H3K27Ac antibodies, after which DNA isolated from extracted immunocomplexes was sequenced.
Project description:HMGB2 and ER ChIPseq was investigated in the MCF-7 endocrine sensitive and LY2 endocrine resistant cell lines upon treatment with Tamoxifen.
Project description:Mot1 is a conserved and essential Swi2/Snf2 ATPase that can remove TATA-binding protein (TBP) from DNA using ATP hydrolysis, and in so doing exerts global effects on transcription. Spt16 is also essential and functions globally in transcriptional regulation as a component of the FACT histone chaperone complex. Here we demonstrate that Mot1 and Spt16 regulate a largely overlapping set of genes in Saccharomyces cerevisiae. As expected, Mot1 was found to control TBP levels at co-regulated promoters. In contrast, Spt16 did not affect TBP recruitment. On a global scale, Spt16 was required for Mot1 promoter localization, and Mot1 also affected Spt16 localization to genes. Interestingly, we find that Mot1 has an unanticipated role in establishing or maintaining the occupancy and positioning of nucleosomes at the 5â ends of genes. Spt16 has a broad role in regulating chromatin organization in gene bodies, including those nucleosomes affected by Mot1. These results suggest that the large-scale overlap in Mot1 and Spt16 function arises from a combination of both their unique and shared functions in transcription complex assembly and chromatin structure regulation. ChIP was performed for Spt16-myc in WT cells and mot1-42 cells in duplicate with input DNA from WT as control. ChIP was performed for Mot1-myc in WT cells and spt16-197 cells in dublicate with input DNA from WT as control. Micrococcal nuclease digested chromatin from WT, mot1-42, spt16-197, and mot1-42 spt16-197 cells were immunoprecipitated with H3 antibody in duplicate. All samples were sequenced by Illumina MiSeq.
Project description:Synthetic DNA-binding proteins have found broad application in gene therapies and as tools for interrogating biology. Engineered proteins based on the CRISPR/Cas9 and TALE systems have been used to alter genomic DNA sequences, control transcription of endogenous genes, and modify epigenetic states. Although the activity of these proteins at their intended genomic target sites have been assessed, the genome-wide effects of their action have not been extensively characterized. Additionally, the role of chromatin structure in determining the binding of CRISPR/Cas9 and TALE proteins to their target sites and the regulation of nearby genes is poorly understood. Characterization of the activity these proteins using modern high-throughput genomic methods would provide valuable insight into the specificity and off-target effects of CRISPR- and TALE-based genome engineering tools. We have analyzed the genome-wide effects of TALE- and CRISPR-based transcriptional activators targeted to the promoters of two different endogenous human genes in HEK293T cells using a variety of high-throughput DNA sequencing methods. In particular, we assayed the DNA-binding specificity of these proteins and their effects on the epigenome. DNA-binding specificity was evaluated by ChIP-seq and RNA-seq was used to measure the specificity of these activators in perturbing the transcriptome. Additionally, DNase-seq was used to identify the chromatin state at target sites of the synthetic transcriptional activators and the genome-wide chromatin remodeling that occurs as a result of their action. Our results show that these genome engineering technologies are highly specific in both binding to their promoter target sites and inducing expression of downstream genes when multiple activators bind to a single promoter. Moreover, we show that these synthetic activators are able to induce the expression of silent genes in heterochromatic regions of the genome by opening regions of closed chromatin and decreasing DNA methylation. Interestingly, the transcriptional activation domain was not necessary for DNA-binding or chromatin remodeling in these regions, but was critical to inducing gene expression. This study shows that these CRISPR- and TALE-based transcriptional activators are exceptionally specific. Although we detected limited binding of off-target sites in the genome and changes to genome structure, these off-target event did not lead to any detectable changes in gene regulation. Collectively, these results underscore the potential for these technologies to make precise changes to gene expression for gene and cell therapies or fundamental studies of gene function. HEK293T cells were transfected in triplicate with plasmids expressing synthetic transcription factors. The synthetic TFs were either (a) dCas9-VP64 fusion protein and a targeting guide RNA (gRNA), or (b) a TALE-VP64 fusion protein engineered to bind to a specific target site in the genome. As a control, cells were transfected with plasmids expressing GFP. After transfection, RNA-seq was used to identify both on-target and off-target binding sites for the synthetic TFs. The data in this submission were generated using the TALE transfection experiments.
Project description:The fate of doubled genes, from allopolyploid or autopolyploid origin, is controlled at multiple levels within the central dogma: gene loss or silencing, neo- and/or sub functionalization, inter genomic transfer, allele dominance/co-dominance, differences in transcription/translation efficiency, post translational modifications… These regulatory processes through evolution have caused a plethora of genotype x environment interactions displayed in the modern day phenotypes. The study of non-model crops is challenging but solutions are emerging. More and more, one gets insight into the tolerance mechanisms of a specific genotype. By integrating transcriptomics into our proteomic data, we studied the genetic diversity of an allopolyploid ABB banana, a tolerant genotype, and compared it to two different sensitive AAA genotypes. The root growth of the ABB cultivar was 60 % higher under mild osmotic stress. 234,000 spectra were aligned and quantified, resulting in 2,753 identified root proteins. 383 gene loci displayed genotype specific differential expression whereof 252 showed at least one Single Amino Acid Polymorphism (SAAP). The homeoallelic contribution was assessed using transcriptome read alignment, thus revealing each allele contribution at the RNA level. This provides insight in the structure and the organization of the triploid genome. In the ABB cultivar, allele expressions are supposed to follow a 1/3 and 2/3 pattern. We found that many genes deviated from this expectation and we show that 32 gene loci even displayed a 100% read preference for the allele that was unique for the ABB tolerant genotype , suggesting that the presence of unique alleles and homoelog expression bias is correlated to the observed phenotype.
Project description:General activation of hypoxia-inducible factor (HIF) pathways is classically associated with adverse prognosis in cancer and has been proposed to contribute to oncogenic drive. In clear cell renal carcinoma (CCRC) HIF pathways are upregulated by inactivation of the von-Hippel-Lindau tumour suppressor. However HIF-1a and HIF-2a have contrasting effects on experimental tumour progression. To better understand this paradox we examined pan-genomic patterns of HIF DNA binding and associated gene expression in response to manipulation of HIF-1a and HIF-2a and related the findings to CCRC prognosis. Our findings reveal distinct pan-genomic organization of HIF isoform-specific DNA binding at thousands of sites. Overall associations were observed between HIF-1a-specific binding, and genes associated with favourable prognosis and between HIF-2a-specific binding and adverse prognosis. However within each isoform-specific set, individual gene associations were heterogeneous in sign and magnitude, suggesting that activation of each HIF-a isoform contributes a highly complex mix of pro- and anti-tumorigenic effects ChIP and RNASeq of HIF-1a and HIF-2a transfection in 786-O cell lines
Project description:DNA Double-Strand Breaks (DSBs) are highly detrimental since they can lead to mutations and chromosomes rearrangements (amplification, deletion, translocation and chromosome loss). Here, we set to assess the tridimensional genome organization around DSBs and its role in DSB repair foci formation. We performed Hi-C experiments before and after DSB induction and upon ctrl or SCC1 depletion, 4C-seq experiments before and after DSB induction and upon cohesin (SCC1) depletion or ATM inhibition. We also performed ChIP-seq of pATM(S1981), CTCF, P-SMC3(S1083), MDC1 and a calibrated ChIP-seq of SCC1 with or without damage. ChIP-chip of SMC3 (S1083) and SMC1 (S966) were used to show the recruitment of these marks on DNA repair foci. ChIP-chip of gammaH2AX was realized upon SCC1 depletion and ChIP-seq of gammaH2AX was realized upon SCC1 or WAPL to show the role of the cohesin complex in gammaH2AX foci formation. ChIP-seq of gammaH2AX was realized upon ATM or ATR inhibition to show that ATM is the major kinase that phosphorylates H2AX at clean breaks in human cells.
Project description:We use ChIP-seq targeting histone 3 lysine 4 mono-methylation (H3K4me1) to identify putative enhancer sites genome-wide, in the retrosplenial cortex of adult prairie vole males. ChIP samples were generated by targeting a known enhancer mark (H3K4me1) in chromatin extracted from the retrosplenial cortex of 8 males. Illumina libraries were prepared from ChIP and INPUT DNA and sequenced on Illimuna HiSeq 2500 platform.