Transcription-associated histone pruning demarcates macroH2A chromatin domains
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PROVIDER: PRJNA431857 | ENA |
REPOSITORIES: ENA
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Project description:Here, we characterized de novo chromatin deposition of macroH2A2 using temporal genomic profiling in cells devoid of all macroH2A isoforms. We find that macroH2A2 is first pervasively deposited genome-wide and subsequently pruned to establish mature domains. This transient incorporation occurs preferentially at transcribed regions adjacent to future mature macroH2A2 domains and transcriptional inhibition prevents the clearing of promiscuously incorporated macroH2A2. Furthermore, CRISPR/Cas9-based manipulation of the transcriptional activity at a given locus reveals that transcriptional silencing triggers ectopic macroH2A2 accumulation, while activation depletes pre-existing macroH2A2. We demonstrate that the FACT (facilitates chromatin transcription) complex is required for macroH2A2 removal from transcribed chromatin. Taken together, we have identified a transcription-associated pruning mechanism that establishes and maintains the faithful genomic localization of macroH2A variants.
2018-10-05 | GSE109740 | GEO
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Project description:Genetic loss-of-function studies in development, cancer and somatic cell reprogramming have suggested that the group of macroH2A histone variants might function through stabilizing the differentiated state by a yet unknown mechanism. Here, we present results demonstrating that macroH2A variants have a major function in maintaining nuclear organization and heterochromatin architecture. Specifically, we find that a substantial amount of macroH2A is associated with heterochromatic repeat sequences. We further identify macroH2A on sites of interstitial heterochromatin decorated by H3K9me3. Loss of macroH2A leads to major defects in nuclear organization including reduced nuclear circularity, disruption of nucleoli and a global loss of dense heterochromatin. Domains formed by repeat sequences when depleted of macroH2A are disorganized, expanded and fragmented and mildly re-expressed. On the molecular level we find that macroH2A is required for the interaction of repeat sequences with the nucleostructural protein Lamin B1. Taken together our results argue that a major function of macroH2A histone variants is to link nucleosome composition to higher order chromatin architecture.
2017-03-21 | GSE58175 | GEO
Project description:Here we report that the histone variant macroH2A acts as a barrier to induced pluripotency. Using fibroblasts isolated from macroH2A double knockout mice, we observed enhanced reprogramming efficiency compared to fibroblasts from wild type animals. We further show that macroH2A isoforms act synergistically in this process. Genomic analysis in wild type fibroblasts reveals that macroH2A1 and H3K27me3 domains co-localize and occupy pluripotency genes. While the absence of macroH2A does not affect H3K27me3 in fibroblasts, macroH2A1 is highly enriched at a set of Utx target genes that are reactivated early during iPS reprogramming. Mononucleosomes from Dermal Fibroblasts (from wt and macroH2A1 and macroH2A2 double knockout mice) were isolated and ChIP'd with mH2A1, H3K27me3 and H3K27ac antibodies. DNA from Input and ChIP samples was purified and sequenced on Illumina's Hiseq.
2013-03-01 | E-GEOD-40813 | biostudies-arrayexpress
Project description:Here we report that the histone variant macroH2A acts as a barrier to induced pluripotency. Using fibroblasts isolated from macroH2A double knockout mice, we observed enhanced reprogramming efficiency compared to fibroblasts from wild type animals. We further show that macroH2A isoforms act synergistically in this process. Genomic analysis in wild type fibroblasts reveals that macroH2A1 and H3K27me3 domains co-localize and occupy pluripotency genes. While the absence of macroH2A does not affect H3K27me3 in fibroblasts, macroH2A1 is highly enriched at a set of Utx target genes that are reactivated early during iPS reprogramming.
2013-03-01 | GSE40813 | GEO
Project description:Eukaryotic chromatin structure is highly conserved, with the canonical histone proteins revealing only small sequence changes across species. Yet, all vertebrates exhibit three much larger histone H2A variants, macroH2A. A distinctive feature of these atypical histones is the globular macrodomain module, which can bind metabolites and is connected to the histone fold through a flexible linker. MacroH2A variants impact heterochromatin organization, transcription regulation and establish a barrier for cellular reprogramming. However, the mechanisms of how these large H2A variants are incorporated into chromatin and the identity of any chaperones required for histone deposition have remained elusive. Here, we developed a split-GFP-based cellular readout for histone incorporation and conducted a genome-wide mutagenesis screen in haploid human cells to identify proteins that regulate macroH2A dynamics. We identified and validated the histone chaperone ANP32B as a regulator of macroH2A chromatin deposition. ANP32B associates with macroH2A in cells and in vitro binds to histones with low nanomolar affinity. In vitro nucleosome assembly assays show that ANP32B stimulates deposition of macroH2A-H2B and not of H2A-H2B onto tetraso me. In cells, depletion of ANP32B in cells strongly affects global macroH2A deposition, revealing ANP32B as a macroH2A chaperone. Our study highlights the power of haploid cell functional genomics coupled with cellular imaging to identify factors that are required for chromatin plasticity and diversity.
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Project description:Interaction proteomics in cell extracts on tagged macroH2A, either expressed in cells or using recombinant dimers with H2B.
2023-10-24 | PXD045696 | Pride
Project description:MacroH2A histone variants have a major role in nuclear organization and large-scale 3D chromatin architecture. How these alterations impinge on the behaviour of cancer cells is not known. Here, we describe the analysis of the total macroH2A loss of function phenotype in a model of hepatoblastoma, the main childhood liver cancer. Performing transcriptomic analyses in xenografts and cell cultures, we find that macroH2A modulated the response of cancer cells to paracrine inflammatory signalling. Specifically, ablation of macroH2A ablation neutralized the induction of a large subset of genes by TNFα and led to the hyperactivation of another subset of genes. Among the top macroH2A-sensitive genes we find the cancer-related gene DKK1 . Depletion of macroH2A rendered the DKK1 gene hypersensitive to TNFα signalling boosting the secretion of DKK1 protein. On the gene regulation level, this was mediated by an alteration of the local chromatin structure and facilitated activation of distal enhancer elements. The study of human samples of hepatoblastoma showed that DKK1 is strongly upregulated in tumors and associated with poor patient outcome. Taken together our results suggest that the regulation of 3D chromatin architecture by macroH2A histone variants has a central role in the response and regulation of paracrine signalling that might be relevant for the interaction of cancers with immune cells and other cells in their microenvironment.
2022-09-20 | GSE161857 | GEO
Project description:MacroH2A histone variants have a major role in nuclear organization and large-scale 3D chromatin architecture. How these alterations impinge on the behaviour of cancer cells is not known. Here, we describe the analysis of the total macroH2A loss of function phenotype in a model of hepatoblastoma, the main childhood liver cancer. Performing transcriptomic analyses in xenografts and cell cultures, we find that macroH2A modulated the response of cancer cells to paracrine inflammatory signalling. Specifically, ablation of macroH2A ablation neutralized the induction of a large subset of genes by TNFα and led to the hyperactivation of another subset of genes. Among the top macroH2A-sensitive genes we find the cancer-related gene DKK1 . Depletion of macroH2A rendered the DKK1 gene hypersensitive to TNFα signalling boosting the secretion of DKK1 protein. On the gene regulation level, this was mediated by an alteration of the local chromatin structure and facilitated activation of distal enhancer elements. The study of human samples of hepatoblastoma showed that DKK1 is strongly upregulated in tumors and associated with poor patient outcome. Taken together our results suggest that the regulation of 3D chromatin architecture by macroH2A histone variants has a central role in the response and regulation of paracrine signalling that might be relevant for the interaction of cancers with immune cells and other cells in their microenvironment.
2022-09-20 | GSE161858 | GEO
Project description:MacroH2As core histone variants have a unique structure that includes C-terminal nonhistone domain. MacroH2As are highly conserved in vertebrates, and are thought to regulate gene expression. However the nature of genes regulated by macroH2As and the biological significance of macroH2As for the organism remain unclear. Our gene expression studies indicate that macroH2A.1 and macroH2A.2 work together to regulate specific genes. In these studies we examine the distributions of macroH2A.1 and macroH2A.2 nucleosomes to determine if they are localized to the genes that show altered expression in macroH2A knockout mouse liver. MacroH2A.1 and macroH2A.2 nucleosomes prepared from ~ 50 fetal mouse livers were purified by thio-affinity chromatography. Five samples were sequenced: Thiopropyl Sepharose, Normal Liver - contains mononucleosomal DNA from macroH2A.1-containing nucleosomes; Activate Thiol Sepharose, Normal Liver - contains mononucleosomal DNA primarily from macroH2A.2-containing nucleosomes. Starting Material, Normal Liver - this is a reference samplefor the first two samples. It contains mononucleosomal DNA from bulk fetal liver chromatin. Activated Thiol Sepharose, Knockout Livers - this is a control sample that contains mononucleosomal DNA from non-macroH2A nucleosomes that contaminate the macroH2A.2 nucleosomes. This fraction was prepared from macroH2A1/2 double knockout fetal livers; Starting Material, Knockout Liver - this is a reference sample for the fourth sample. It contains mononucleosomal DNA from bulk chromatin prepared from macroH2A1/2 double knockout fetal livers.
2014-10-15 | E-GEOD-57796 | biostudies-arrayexpress