Project description:The histone variant H2A.Z is evolutionarily conserved from yeast to vertebrates. H2A.Z regulates gene expression when localized to promoter region. Recently, we identified two genes encoding H2A.Z, H2A.Z-1 and H2A.Z-2 in vertebrate genome. However, it is not clear that both H2A.Z-1 and H2A.Z-2 were required for the function of H2A.Z in gene regulation. To address this issue, we generated the H2A.Z-1 and H2A.Z-2 double knock out (KO) cells in chicken DT40 cells. The expression pattern of H2A.Z-1 and H2A.Z-2 double KO cells was compared with WT cells to characterize the genes regulated by H2A.Z-1 and H2A.Z-2. We used microarrays to analysis the alternation of gene expression between WT and H2A.Z double KO cells and identify classes of up or down regulated gene by H2A.Z-1 and H2A.Z-2. In H2A.Z-1 and H2A.Z-2 double KO cells, H2A.Z-2 is knocked out constitutively, but H2A.Z-1 conditionally by tetracycline. The expression of H2A.Z-1 transgene is suppressed completely when H2A.Z-1 and H2A.Z-2 double KO cells culture with tetracycline for three days. For this reason, we prepared the total RNA of WT cells and H2A.Z-1and H2A.Z-2 double KO cells treated with tetracycline for three days and hybridization on Affymetrix microarrays.
Project description:The histone variant H2A.Z is evolutionarily conserved from yeast to vertebrates. H2A.Z regulates gene expression when localized to promoter region. Recently, we identified two genes encoding H2A.Z, H2A.Z-1 and H2A.Z-2 in vertebrate genome. However, it is not clear that both H2A.Z-1 and H2A.Z-2 were required for the function of H2A.Z in gene regulation. To address this issue, we generated the H2A.Z-1 and H2A.Z-2 double knock out (KO) cells in chicken DT40 cells. The expression pattern of H2A.Z-1 and H2A.Z-2 double KO cells was compared with WT cells to characterize the genes regulated by H2A.Z-1 and H2A.Z-2. We used microarrays to analysis the alternation of gene expression between WT and H2A.Z double KO cells and identify classes of up or down regulated gene by H2A.Z-1 and H2A.Z-2.
Project description:To understand how chromatin structure is organized by different histone variants, we have measured the genome-wide distribution of nucleosome core particles (NCPs) containing the histone variants H3.3 and H2A.Z in human cells. We find that a special class of NCPs containing both variants is enriched at ‘nucleosome-free regions’ of active promoters, enhancers and insulator regions. We show that preparative methods used previously in studying nucleosome structure result in the loss of these unstable double-variant NCPs. It seems likely that this instability facilitates the access of transcription factors to promoters and other regulatory sites in vivo. Other combinations of variants have different distributions, consistent with distinct roles for histone variants in the modulation of gene expression. genome-wide analysis of histone variants H2AZ, H3.3, and H3.3-H2A.Z double ChIP, plus input and genomic DNA controls in HeLa cells. H2A.Z samples are prepared under two different salt concentration conditions. (6 samples in total)
Project description:We report a genome wide enrichment, redistribution and accumulation of H2A.Z at specific chromatin control regions, in particular at enhancers and insulators, in mouse embryonic fibroblasts depleted for Anp32e (MEFs Anp32e-/-). H2A.Z ChIP-seq in MEFs WT (+/+) or KO (-/-) for Anp32e.
Project description:While the histone variant H2A.Z is known to be required for mitosis, it is also enriched in nucleosomes surrounding the transcription start site of active promoters, implicating H2A.Z in transcription. However, evidence obtained so far mainly rely on correlational data generated in actively dividing cells. We have exploited a paradigm in which transcription is uncoupled from the cell cycle by developing an in vivo system to inactivate H2A.Z in terminally differentiated post-mitotic muscle cells. ChIP-seq, RNA-seq and ATAC-seq experiments performed on H2A.Z KO post-mitotic muscle cells show that this histone variant is neither required to maintain nor to activate transcription. Altogether, this study provides in vivo evidence that in the absence of mitosis H2A.Z is dispensable for transcription and that the enrichment of H2A.Z on active promoters is a marker but not an active driver of transcription.
Project description:In eukaryotes, DNA wraps around histones to form nucleosomes, which are compacted into chromatin. DNA-templated processes, including transcription, require chromatin disassembly and reassembly mediated by histone chaperones. Additionally, distinct histone variants can replace core histones to regulate chromatin structure and function. Although replacement of H2A with the evolutionarily conserved H2A.Z via the SWR1 histone chaperone complex has been extensively studied, in plants little is known about how a reduction of H2A.Z levels can be achieved. Here, we show that NRP proteins cause a decrease of H2A.Z-containing nucleosomes in Arabidopsis under standard growing conditions. nrp1-1 nrp2-2 double mutants show an over-accumulation of H2A.Z genome-wide, especially at heterochromatic regions normally H2A.Z-depleted in wild-type plants. Our work suggests that NRP proteins regulate gene expression by counteracting SWR1, thereby preventing excessive accumulation of H2A.Z.
Project description:To transcriptomic differences among control, Nf2 KO, Rasa1 KO, and double KO S1 tumorspheres We then performed gene expression profiling analysis using data obtained from RNA-seq of control, Nf2 KO, Rasa1 KO, and double KO S1 tumorspheres.
Project description:While it has been clearly established that well positioned H2A.Z-containing nucleosomes flank the nucleosome depleted region (NDR) at the transcriptional start site (TSS) of active mammalian genes, how this chromatin-based information is transmitted through the cell cycle is unknown. We show here that in trophoblast stem (TS) cells, the level of H2A.Z at promoters decreases during S phase coinciding with homotypic (H2A.Z/H2A.Z) nucleosomes flanking the TSS becoming heterotypic (H2A.Z/H2A). Surprisingly, these nucleosomes remain heterotypic at M phase. At the TSS, we identify an unstable heterotypic H2A.Z-containing nucleosome in G1 which, strikingly, is lost following DNA replication. These dynamic changes in H2A.Z at the TSS mirror a global expansion of the NDR at S and M which, unexpectedly, is unrelated to transcriptional activity. Coincident with the loss of H2A.Z at promoters, it is targeted to the centromere when mitosis begins We performed ChIP-Seq experiments (on mouse Trophoblast Stem cells arrested at G1; S and M stages of thecell cycle) using antibodies against histone variant H2A.Z and sequentional ChIP-re-ChIP-Seq experiments using H2A.Z antibody and H2A antibody in sequence. Combining those data sets with microarray gene expression expression data allowed us to see H2A.Z distribution over promoters of mouse coding genes in cell cycle dependant manner. Interestingly, Input also showed cell-cycle dependent effects, but histone H3 could be used as a cell-cycle independent normalisation factor. We also performed ChIP-seq with a CTCF pull-down to investigate its cell-cycle dependent relationship with heterochromatin.