Project description:Chromatin immunoprecipitation with antibodies specific for histone modifications H3K4me3, H3K9ac and H3K27me3 and subsequent high-throughput sequencing were performed on fixed chromatin from two septic disease patients. ChIP-seq
Project description:Chromatin immunoprecipitation in combination with a genome-wide analysis via high-throughput sequencing is the state of the art method to gain genome-wide representation of histone modification or transcription factor binding profiles. However, chromatin immunoprecipitation analysis in the context of human experimental samples is limited, especially in the case of blood cells. The typically extremely low yields of precipitated DNA are usually not compatible with library amplification for next generation sequencing. We developed a highly reproducible protocol to present a guideline from the first step of isolating monocytes from a blood sample to analyse the distribution of histone modifications in a genome-wide manner. ChIP-seq histone modifications in CD14++ CD16- monocytes from human blood samples
Project description:The fidelity of chromosome duplication through cell divisions requires timely binding and release of the cohesin. Cohesin is a ring-shaped protein complex linking newly replicated sister chromatids to ensure their appropriate transmission through mitosis. Upon commencement of mitosis cohesin is removed from DNA in two steps: first, from chromosome arms resulting in sister chromatid resolution, and, second, from centromers leading to sister chromatid segregation. As DNA of eukaryotic chromosomes is assembled into chromatin, regulation of sister chromatid cohesion-segregation may involve chromatin modifying machinery, but this link is not well understood. Here we report that H2A-H2B histone chaperone NAP1, a factor, which is primarily implicated in chromatin assembly, is required for cohesin release from mitotic chromosome arms. NAP1 and cohesin protein complex interact directly and share multiple binding sites on chromatin. Depletion of the NAP1 hinders cohesin removal during mitosis resulting in accumulation of unresolved sister chromatids. Thus, in addition to its well established functions in chromatin dynamics, histone chaperone NAP1 coordinates cell cycle dependent cohesin release. These results reveal a novel molecular pathway for sister chromatid resolution and emphasizes a role for histone chaperones in control of eukaryotic genome replication and transmission. Genome-wide NAP1 and Cohesin ChIP-chip profiling in Drosophila S2 cells. The supplementary bed file S2_cohesin_sites.bed contains cohesin binding sites obtained by intersecting the sets of significant ChIP-chip peaks for SA (a cohesin subunit; stromalin) and SMC1.
Project description:Enhancers are developmentally-controlled transcriptional regulatory regions whose activities are modulated through histone modifications or histone variant deposition. Here, we show by genome-wide mapping that the newly discovered DNA modification 5-hydroxymethylcytosine (5hmC) is dynamically associated with transcription factor binding to distal regulatory sites during neural differentiation of mouse P19 cells as well as during adipocyte differentiation of mouse 3T3-L1 cells. Functional annotation reveals that regions gaining 5hmC are associated with genes expressed either in neural tissues when P19 cells undergo neural differentiation or in adipose tissue when 3T3-L1 cells undergo adipocyte differentiation. Furthermore, distal regions gaining 5hmC together with H3K4me2 and H3K27ac in P19 cells behave as differentiation-dependent transcriptional enhancers. Identified regions are enriched in motifs for transcription factors regulating specific cell fates like Meis1 in P19 cells and PPARgamma in 3T3-L1 cells. Accordingly, a fraction of hydroxymethylated Meis1 sites were associated with a dynamic engagement of the 5mC hydroxylase Tet1. In addition, kinetic studies of cytosine hydroxymethylation of selected enhancers indicated that DNA hydroxymethylation is an early event of enhancer activation. Hence, acquisition of 5hmC in cell-specific distal regulatory regions may represent a major event of enhancer progression toward an active state and participate in selective activation of tissue-specific genes MEIS1 and H3K27ac genome-wide distributions were determined using ChIP-seq. Cells used in this study are P19.6 mouse embryonal carnicoma cells and P19.6 cells treated for 48 hours with 1M-BM-5M all-trans retinoic acid (RA). ChIP samples were done by SM-CM-)randour A.A. Libraries were prepared and sequenced by the IGBMC sequencing facility (Strasbourg, France) by an Illumina Genome Analyzer II.
Project description:The p53-regulated long non-coding RNA, lincRNA-p21, has been proposed to promote apoptosis and to repress in trans the expression of genes in the p53 transcriptional network. Here, we report the generation of a conditional knockout mouse model developed to further examine lincRNA-p21 function. Using this genetic approach, we find that the primary function of lincRNA-p21 is to activate in cis the expression of its neighboring gene, the cyclin-dependent kinase inhibitor p21. Mechanistically, we show that lincRNA-p21 acts in concert with hnRNP-K as a co-activator for p53-dependent transcription of p21. Additional phenotypes of lincRNA-p21 deficiency, including deregulated expression and altered chromatin state of a set of Polycomb target genes, defective G1/S checkpoint, increased proliferation rates, and enhanced reprogramming efficiency could be attributed to diminished p21 levels. This study reveals a novel paradigm, whereby the long non-coding RNA lincRNA-p21 affects global gene expression and influences events in the p53 tumor suppressor pathway by acting in cis as a locus-restricted transcriptional co-activator for p53-mediated expression of p21. Examination of 2 different histone modifications (H3K4me3 and H3K27me3) in 2 cell types (WT and lincRNA-p21 KO) in the presence and absence of Doxorubicin.
Project description:Cellular metabolism and chromatin landscape both contribute to cell fate determination. However, their interplay remains poorly understood. Here we show that Prohibitin (PHB), an evolutionarily conserved protein, involves in a histone variant H3.3 chaperon HIRA complex-dependent epigenetic and metabolic circuitry to maintain the identity of human embryonic stem cells (hESCs). We found that silencing of PHB triggers hESC differentiation with concomitant enhancements of histone 3 (H3) lysine (K) methyl modifications as a result of the reduced production of α-ketoglutarate (α-KG), a metabolite required for activities of many dioxygenase and in turn chromatin structure1,2. Mechanistically, PHB acts as a functional member of the HIRA complex3,4. Resembling PHB deficiency, loss of HIRA in hESCs leads to massive differentiation and aberrant histone modifications, although it was previously found not to disrupt the self-renewal in mouse ESCs (mESCs)5. Genome-wide H3.3 ChIP- sequence analyses indicate that reduction of H3.3 deposition caused by PHB knock down is extremely similar to that induced by HIRA knock down. Specifically, silencing either HIRA or PHB leads to repressive chromatin characters at promoters of pluripotency genes and isocitrate dehydrogenases (IDHs), the enzyme responsible for α-KG production, but active chromatin features at promoters of developmental genes, paralleling to transcript levels of these genes. Our results identify PHB as an essential factor not only for hESC self-renewal but also for the proper function of the HIRA complex, linking the HIRA complex-dependent H3.3 deposition to the production of a critical metabolite required for shaping chromatin structure, and demonstrating the importance of the interplay between epigenetic state and metabolic regulation in cell fate determination. Examination of H3.3 deposition in NT, PHB, and HIRA siRNA treated hESCs respectively.
Project description:ChIP-seq for H3K27me3 and Ring1B was performed in WT mESCs and mESCs containing catalytically inactive Ring1B (I53A mutant). Cells expressing catalytically inactive Ring1B maintain the spatial distribution of Ring1B and H3K27me3 but at reduced levels. These findings support the notion that PRC2 recruitment is, in part, dependent on H2A ubiquitination (H2AK119ub). Two biological replicates were performed for Ring1B and H3K27me3 ChIPs in WT and Ring1B I53A/I53A mouse ESCs. Input chromatin was sequenced for each replicate as a control for ChIP enrichment.
Project description:ChIP-seq of ASY1 was carried out on meiotic-stage floral buds of Arabidopsis using an a-ASY1 antibody. The experiment aims to determine the genome-wide profile of ASY1. ASY1 is a component of the chromosome axis and is expressed exclusively during meiosis. Two negative controls were used to test the specificity of the ChIP experiment. First, ChIP-seq using the pre-immune on floral buds was carried out. Second, ChIP-seq using an a-ASY1 antibody was performed on leaf tissue where ASY1 is not expressed.