Project description:Although the locations of promoters and enhancers have been identified in several cell types, we have yet limited information on their connectivity. We developed HiCap, which combines Hi-C with promoter sequence capture, to enable genome-wide identification of regulatory interactions with single-enhancer resolution. HiCap analyses of mouse embryonic stem cells (mESC) identified promoter-enhancer interactions predictive of gene expression change upon perturbation, opening up for genomic analyses of long-range gene regulation. HiCap was designed by combining Hi-C with with sequence capture (for all promoters) and carried out in mouse embryonic stem cells (mESC)
Project description:Here we have developed a method to identify chromatin-bound partners of a protein of interest by selective isolation of chromatin-associated proteins (SICAP) followed by mass spectrometry. We applied SICAP to identify chromatin-binding proteins associated to Oct4, Sox2 and Nanog in mouse embryonic stem (ES) cells.
Project description:Triple Negative Breast Cancer (TNBC) is an aggressive subtype of breast cancer with high intra-tumoral heterogeneity, frequently resistant to treatment and no known targeted therapy available to improve patient outcomes. It has been hypothesized that the genomic architecture of a TNBC tumour evolves over time, both before, and during therapy, leading to therapy resistance and a high propensity to relapse. Whether this is an inherent property of the tumour or acquired over time is not well characterized. Despite this important clinical implication, limited studies have been carried out to unravel temporal evolution of TNBC over time. Herein, we report an OMICS based analysis of three TNBC patients who were longitudinally sampled during their treatment at different times of relapse. We recruited three TNBC patients at the time of their first relapse who were then followed-up through the course of their treatment. We obtained retrospective samples (tumour samples) from patient tumours at diagnosis (before neo-adjuvant chemotherapy - NACT) at surgery (post NACT) and prospectively sampled them at each subsequent relapse (tumour, blood plasma, and buffy coat) as determined by RECIST criteria. Tumor and buffy coat DNA were subjected to whole exome sequencing (WES) at 200x, and SNP arrays for copy number variation (CNV) analysis. RNA from tumour samples at relapse was subjected to whole transcriptome sequencing. Pathogenic germline BRCA1 variants identified in WES were validated using Sanger sequencing. 1084 somatic mutations identified in whole exome sequencing of all tumour tissues (n=13) from three patients, were subjected to a custom amplicon ultra-deep sequencing assay at 30,000X in their germline DNA (n=3), tumour DNA (n=10), and cfDNA from plasma samples at relapse (n=8). Copy number corrected allele frequencies, tumour ploidy, tumour purity, and ultra-deep sequencing assay derived variant allele frequencies were used to infer clonal and phylogenetic architecture of each patient as it evolved under selective pressure of therapy over time. Clonality analysis incorporating allele fractions from ultra-deep sequencing identified clones comprising of mutations that are present throughout the course of therapy which we term as founding clones and stem mutations respectively. Such founding clones comprising of stem mutations in all 3 patients were present throughout the course of treatment, irrespective of change in treatment modalities. These stem clones included well characterized cancer related genes like PDGFRB & ARID2 (Patient 02), TP53, BRAF & CSF3R (Patient 04) and ESR1, APC, EZH2 & TP53 (Patient 07). Such branching evolution is seen in all three patients wherein the dominant clone (stem clone) acquires additional mutations to form sub-clones, while persisting over time. These sub-clones may be chemo and radio resistant, while also providing for organ specific metastatic potential. Allele fractions of expressed variants inferred from RNA-Seq data co-related with allele fractions from WES data indicating that all somatic.
Project description:Chromatin organisation of trophoblast stem cells (TSC) were compared with that of embryonic stem cells (ESC). The method enriches Hi-C libraries, to detect promoter interactions at restriction fragment level. We prepared Hi-C libraries from TSC and ESC (serum grown) samples and enriched them with a promoter capture bait system that captures ~22.000 promoters. Promoter interactions were then analysed using the GOTHiC pipeline.
Project description:Glucocorticoid receptor (GR) is an essential transcription factor (TF), controlling metabolism, development and immune responses. SUMOylation regulates chromatin occupancy and target gene expression of GR in a locus-selective manner, but the mechanism of regulation has remained elusive. Here, we show using selective isolation of chromatin-associated proteins that the protein network around chromatin-bound GR is affected by SUMOylation, with several nuclear receptor coregulators and chromatin modifiers being more avidly associated with SUMOylation-deficient than SUMOylation competent GR. This difference is reflected in our chromatin accessibility and gene expression data, showing that the SUMOylation-deficient GR is more potent in opening chromatin at glucocorticoid-regulated enhancers and inducing expression of their target loci. Our results thus show that SUMOylation determines GR specificity by regulating the chromatin protein network and accessibility at GR-driven enhancers. We speculate that a similar mechanism is utilized by many other SUMOylated TFs.
Project description:3D structure of a 2.3 Mb region of human chromosome 12 (chr12: 6,140,000-8,460,000) containing GAPDH and NANOG loci in human IMR90 fibroblasts (hFibs) and fibroblast-derived human induced pluripotent stem cell (hiPSCs)
Project description:We used TraDIS-Xpress to determine the mechanism of action of a novel antimicrobial compound. We found that it inhibits lipid IVA biosynthesis in both Escherichia coli and Salmonella enterica serovar Typhimurium. We also were able to determine mechanisms of synergy with colistin, through ATP biosynthesis and the BasSR signalling system.
Project description:The small protein AtpΘ (encoded by gene atpT) identified in cyanobacteria becomes maximum expressed during low-energy conditions such as during darkness. In the model cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis 6803), AtpΘ was demonstrated to inhibit the ATP hydrolysis activity of the F0F1 ATP synthase. Here, the regulation of atpT gene expression was studied in greater detail. The darkness-induced activation of the atpT promoter indicated the existence of regulatory factors. To identify such factors, DNA-protein affinity precipitation was performed using biotinylated DNA fragments. These fragments contained either the promoter-5’UTR (PatpT66-5’UTR) as bait or, as negative control, only the 5’UTR (atpT 5’UTR). Each DNA fragment was incubated with total protein samples isolated from exponential phase Synechocystis 6803 which had been kept in the light or 12 h in darkness prior to protein preparation. The resulting protein samples were then analyzed by mass spectrometry.
Project description:Recent studies have revealed the importance of long noncoding RNAs (lncRNAs) as tissue-specific regulators of gene expression. There is ample evidence that distinct types of vasculature undergo tight transcriptional control to preserve their structure, identity, and functions. We determined, for the first time, the global lineage-specific lncRNAome of human dermal blood and lymphatic endothelial cells (BECs and LECs), combining RNA-Seq and CAGE-Seq. A subsequent genome-wide antisense oligonucleotide-knockdown profiling of two BEC- and two LEC-specific lncRNAs identified LETR1 as a critical gatekeeper of the global LEC transcriptome. Deep RNA-DNA and RNA-protein interaction studies, and phenotype rescue analyses revealed that LETR1 is a nuclear trans-acting lncRNA modulating, via key epigenetic factors, the expression of essential target genes governing the growth and migratory ability of LECs. Together, our study provides new evidence supporting the intriguing concept that every cell type expresses precise lncRNA signatures to control lineage-specific regulatory programs.
Project description:We generated Hi-C interaction maps of iPSC and iPSC-derived cardiomyocytes as a resource to help identifying regulatory elements and their target genes in these tissues.