Genome-wide maps of chromatin state during cardiac reprogramming of human fibroblasts by small molecules
ABSTRACT: Cardiomyocyte-like cells can be reprogrammed from somatic fibroblasts by overexpression of cardiac genes, providing a new avenue for cardiac regenerative therapy. Here we report an alternative approach in which functional cardiomyocytes can be rapidly and efficiently generated from human fibroblasts by a specific combination of small molecules. ChIP-seq analysis has been used to understand the dynamic changes in chromatin state during early stage of reprogramming. We analyzed the genome-wide epigenetic changes by ChIP-seq analysis of H3K4me3 and H3K27ac (active chromatin marks) and H3K27me3 (inactive chromatin mark) at reprogramming Day 6 (D6) and day 11 (D11).
Project description:Estrogen Receptor is a key transcriptional regulator in mammary gland development and breast cancer. In this study, we have mapped the Estrogen Receptor chromatin binding patterns in healthy mouse mammary gland A minimum of 6 pairs of mouse mammary gland pads from mice at 5-6 weeks of age were excised and Estrogen Receptor ChIp-seq was performed.
Project description:NUCKS has a DNA binding domain at C-terminal region. We found that NUCKS has important roles in regulating glucose homeostasis. To get an unbiased handle on the plausible mechanism(s) of NUCKS action, we performed a genome-wide Chromatin Immunoprecipitation (ChIP)-sequencing for NUCKS in primary hepatocytes. We successfully mapped 25mln reads to the mm9 genome and detected NUCKS binding at 10203 sites, 60% of which were located in the proximity of a Transcription Start Sites (TSS). The peaks of NUCKS occupancy were often broad with some around 1Kb, suggesting that multiple NUCKS molecules could bind cooperatively to the same genomic loci. This study provides information of NUCKS binding sites in Mus musculus genome. Examination of NUCKS binding in mouse primary hepatocytes by Chromatin immunoprecipitation followed by deep sequencing.
Project description:The phenomenon of nucleosome retention in mammalian sperm chromatin is still not clarified yet. The goal of our study was to characterize the binding sites of sperm nucleosomes in the human and bovine genomes, and through this, to clarify whether nucleosome retention in sperm underlies rules of great generality and has a biological function. Comparing two mammalian systems we found that nucleosomes remain mainly in centromeres and in non-coding intergenic and intron regions. In contrast, coding DNA, promoter regions and transcription start and end sites, especially in homeobox genes and in the majority of genes with relevance for organ development and morphogenesis, were nucleosome-free. 146 bp mono-nucleosomal DNA was isolated and purified from sperm samples of two fertile bulls (bos taurus), one fertile man and a pool of four fertile donors; each DNA sample was deep sequenced using Illumina GAIIx and genome-wide mapped on respective genome; nucleosome-binding sites were analyzed in a genome-wide comparative manner.
Project description:Estrogen Receptor (ESR1) drives growth in the majority of human breast cancers by binding to regulatory elements and inducing transcription events that promote tumor growth. Differences in enhancer occupancy by ESR1, contribute to the diverse expression profiles and clinical outcome observed in breast cancer patients. GATA3 is an ESR1 co-operating transcription factor mutated in breast tumors, however its genomic properties are not fully defined. In order to investigate the composition of enhancers involved in estrogen-induced transcription and the potential role of GATA3, we performed extensive ChIP-sequencing in unstimulated breast cancer cells and following estrogen treatment. We find that GATA3 is pivotal in mediating enhancer accessibility at regulatory regions involved in ESR1-mediated transcription. GATA3 silencing resulted in a global redistribution of co-factors and active histone marks prior to estrogen stimulation. These global genomic changes altered the ESR1 binding profile that subsequently occurred following estrogen, with events exhibiting both loss and gain in binding affinity, implying a GATA3 mediated re-distribution of ESR1 binding. The GATA3-mediated re-distributed ESR1 profile correlated with changes in gene expression, suggestive of its functionality. Chromatin loops at the TFF locus involving ESR1 bound enhancers occurred independently of ESR1 when GATA3 was silenced, indicating that GATA3, when present on the chromatin, may serve as a licensing factor for estrogen- ESR1 mediated interactions between cis-regulatory elements. Together these experiments suggest that GATA3 directly impacts ESR1 enhancer accessibility and may potentially explain the contribution of mutant-GATA3 in the heterogeneity of ESR1+ breast cancer. GATA and ER binding studied by chromatin immunoprecipitation in breast cancer cell lines, with and without estrogen stimulation and by knocking down GATA
Project description:The Mediator complex orchestrates multiple transcription factors with the Pol II apparatus for precise transcriptional control. However, its interplay with the surrounding chromatin remains poorly understood. Here, we analyze differential histone modifications between WT and MED23-/- (KO) cells and identify H2B mono-ubiquitination at lysine 120 (H2Bub) as a MED23-dependent histone modification. Using tandem affinity purification and mass spectrometry, we find that MED23 associates with the RNF20/40 complex, the enzyme for H2Bub, and show that this association is critical for the recruitment of RNF20/40 to chromatin. In a cell-free system, Mediator directly and substantially increases H2Bub on recombinant chromatin through its cooperation with RNF20/40 and the PAF complex. Integrative genome-wide analyses show that MED23 depletion specifically reduces H2Bub on a subset of MED23-contolled genes. Importantly, MED23-coupled H2Bub levels are oppositely regulated during myogenesis and lung carcinogenesis. In sum, these results establish a mechanistic link between the Mediator complex and a critical chromatin modification in coordinating transcription with cell growth and differentiation. To examine the enrichment of H2B ubiquitination, Pol II, H3K4me3, H3K79me3 in WT and KO MED23 MEF cells, we performed H2Bub ChIP-seq, Pol II ChIP-seq, H3K4me3 ChIP-seq and H3K79me3 ChIP-seq assays. 10 high-throughput sequencing data were deposited and WT, KO input data were controls for peak calling.
Project description:We investigated the cardiac transcription network driven by the DNA-binding key factor Srf in combination with epigenetic marks of histone 3 acetylation (H3ac). Srf has been shown to play a key role in cardiac cell growth and muscle gene regulation. However, we still have limited understanding of the global transcription network driven by this factor in a direct or indirect manner. Moreover, we lack knowledge to which extent epigenetic marks such as histone modifications interfere with the regulation of direct targets. To gain insights into the transcriptional regulatory network two independent chromatin immunoprecipitation (ChIP) samples were profiled. DNA fragments bound to Srf or modified with acetylated histone 3 in mouse cardiomyocytes (HL1-cells) were sequenced using ultra-high throughput DNA sequencing. ChIP-seq profile of a transcription factor (Srf) and a histone modification (H3ac)
Project description:To determine which of the genes differentially expressed between P1-rr and P1-ww pericarps were immediate (direct) targets of P1, we conducted chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-Seq) using P1 polyclonal antibodies (alphaP1344) that recognize the non-conserved C-terminal region of P1 (Falcone Ferreyra et al., 2010), on pericarp chromatin. Comparison of pericarp chromatin inmunoprecipitated material P-rr_14DAP (P1 expressed) vs P-ww_14DAP (P1 not expressed) to determine P1 direct targets
Project description:Our findings establish a key role for LRH-1 in the regulation of ERa target genes in breast cancer cells and identify a mechanism in which co-operative binding of LRH-1 and ERa at estrogen response elements controls the expression of estrogen responsive g Examination of ERα, with or without LRH-1 knockdown, and HA-LRH-1 in MCF-7 cells
Project description:Adult germline stem cells (AGSCs) are multifunctional - they must self renew, maintain genome pluripotency, and prepare for gametogenesis – which involves meiotic and chromatin repackaging phases. To better understand AGSCs and gametogenesis, we derived high-resolution profiles of transcription, DNA methylation, 5hmC, and multiple histone modifications at key stages. First, AGSCs display chromatin ‘poising’ of enhancers and promoters of genes utilized in embryo development. Second, the pluripotency network in AGSCs is remarkably distinct from ESCs - lacking Nanog, Sox2, or Prdm14 expression. Third, spermatogenesis involves stage-specific transcription and distinctive chromatin dynamics, but virtually no changes in DNAme. Surprisingly, we observe co-incidence of RNA polymerase II, high H3K4me3, and DNA methylation at 20-35% of genes transcribed during gametogenesis - including piRNA clusters - but often observe attendant promoter 5hmC. Our work reveals key differences between AGSCs and other germ/stem cells, and reveals both logical and unexpected chromatin-transcription relationships accompanying germline developmental transitions. Examination of 7 different histone modifications and 5hMC in 4 different cell types
Project description:Reactivation of the pluripotency network during somatic cell reprogramming by exogenous transcription factors involves chromatin remodeling and the recruitment of RNA polymerase II (Pol II) to target loci. Here, we report that Pol II is engaged at pluripotency promoters in reprogramming but remains paused and inefficiently released. We also show that bromodomain-containing protein 4 (BRD4) stimulates productive transcriptional elongation of pluripotency genes by dissociating the pause release factor P-TEFb from an inactive complex containing HEXIM1. Consequently, BRD4 overexpression enhances reprogramming efficiency and HEXIM1 suppresses it, whereas Brd4 and Hexim1 knockdown do the opposite. We further demonstrate that the reprogramming factor KLF4 helps recruit P-TEFb to pluripotency promoters. Our work thus provides a mechanism for explaining the reactivation of pluripotency genes in reprogramming and unveils an unanticipated role for KLF4 in transcriptional pause release. Pol II ChIP-seq for MEFs, ESCs and bulk populations of OSKM reprogramming intermediates at two time points.