The repressive role of H2A.Z variant in transcriptional regulation depends on AtBMI1 activity in Arabidopsis
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE117969 | GEO | 2019/05/24
REPOSITORIES: GEO
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Project description:Eukaryotic chromatin is separated into functional domains differentiated by posttranslational histone modifications, histone variants, and DNA methylation. Methylation is associated with repression of transcriptional initiation in plants and animals, and is frequently found in transposable elements. Proper methylation patterns are critical for eukaryotic development, and aberrant methylation-induced silencing of tumor suppressor genes is a common feature of human cancer. In contrast to methylation, the histone variant H2A.Z is preferentially deposited by the Swr1 ATPase complex near 5' ends of genes where it promotes transcriptional competence. How DNA methylation and H2A.Z influence transcription remains largely unknown. Here we show that in the plant Arabidopsis thaliana, regions of DNA methylation are quantitatively deficient in H2A.Z. Exclusion of H2A.Z is seen at sites of DNA methylation in the bodies of actively transcribed genes and in methylated transposons. Mutation of the MET1 DNA methyltransferase, which causes both losses and gains of DNA methylation, engenders opposite changes in H2A.Z deposition, while mutation of the PIE1 subunit of the Swr1 complex that deposits H2A.Z17 leads to genome-wide hypermethylation. Our findings indicate that DNA methylation can influence chromatin structure and effect gene silencing by excluding H2A.Z, and that H2A.Z protects genes from DNA methylation. Keywords: Affinity-purification on microarray All experiments were done using two channels per chip. DNA methylation experiments compared immunoprecipitated, methylated DNA to control genomic DNA. H2A.Z experiments compared whole micrococcal nuclease-treated affinity-purified chromatin to input chromatin used for affinity purification. Affinity purification was performed using either biotin-tagged H2A.Z, pulled down using streptavidin, or endogenous H2A.Z pulled down using an anti-H2A.Z antibody.
2008-10-02 | E-GEOD-12212 | biostudies-arrayexpress
Project description:Eukaryotic chromatin is separated into functional domains differentiated by posttranslational histone modifications, histone variants, and DNA methylation. Methylation is associated with repression of transcriptional initiation in plants and animals, and is frequently found in transposable elements. Proper methylation patterns are critical for eukaryotic development, and aberrant methylation-induced silencing of tumor suppressor genes is a common feature of human cancer. In contrast to methylation, the histone variant H2A.Z is preferentially deposited by the Swr1 ATPase complex near 5' ends of genes where it promotes transcriptional competence. How DNA methylation and H2A.Z influence transcription remains largely unknown. Here we show that in the plant Arabidopsis thaliana, regions of DNA methylation are quantitatively deficient in H2A.Z. Exclusion of H2A.Z is seen at sites of DNA methylation in the bodies of actively transcribed genes and in methylated transposons. Mutation of the MET1 DNA methyltransferase, which causes both losses and gains of DNA methylation, engenders opposite changes in H2A.Z deposition, while mutation of the PIE1 subunit of the Swr1 complex that deposits H2A.Z17 leads to genome-wide hypermethylation. Our findings indicate that DNA methylation can influence chromatin structure and effect gene silencing by excluding H2A.Z, and that H2A.Z protects genes from DNA methylation. Keywords: Affinity-purification on microarray
2008-10-03 | GSE12212 | GEO
Project description:ANP32e, a chaperone of H2A.Z, is receiving increasing attention because of its link to cancer growth and progression. An unanswered question is whether ANP32e regulates H2A.Z dynamics during the cell cycle; if so, this could have clear implications for the proliferation of cancer cells. Using the human U2OS cancer cell line model system, we have confirmed that ANP32e regulates the growth of these cells. ANP32e preferentially interacts with H2A.Z during G1 phase of the cell cycle. Unexpectedly, however, ANP32e does not mediate the removal of H2A.Z from chromatin, is not a stable component of the p400 remodeling complex, and is not strongly associated with chromatin. Instead, most ANP32e is in the cytoplasm. Here, ANP32e preferentially interacts with H2A.Z in G1 phase in response to an increase in H2A.Z protein abundance and regulates its protein stability. This G1-specific interaction between ANP32e and H2A.Z is also observed in the nucleoplasm but is unrelated to any change in H2A.Z abundance. Collectively, these results challenge the idea that ANP32e is involved in regulating the abundance of H2A.Z in chromatin as part of a chromatin remodeling complex. Rather, we propose that ANP32e acts as a molecular chaperone that maintains the soluble pool of H2A.Z by regulating its protein stability and acting as a buffer in response to cell cycle-dependent changes in H2A.Z abundance.
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Project description:H2A.Z acetylation has been suggested to regulate genes but effects on gene expression globally have not been reported. We find that the H2A.Z acetylation sites are required for normal growth in the presence of caffeine and therefore examined the gene expression response to caffeine when H2A.Z can’t be acetylated. Surprisingly we found little or no change in gene induction but a marked failure to remove H2A.Z from activated promoters. Caffeine causes a proteasome-dependent degradation of H2A.Z that is impaired in the absence of the H2A.Z acetylation sites. The proteasomal regulator Blm10 that has previously been implicated in acetylation-dependent histone degradation is required for H2A.Z degradation, revealing a novel role for acetylation in regulating H2A.Z protein levels. When H2A.Z levels are raised, either through loss of the acetylation sites or overexpression of the protein, a shared set of genes aberrantly retains H2A.Z at their 5’ ends during the caffeine response. As a result, expression of these genes fails to return to normal levels. H2A.Z is therefore subject to post-translational proteasomal regulation that controls protein levels, and the fine-tuning of gene expression during a stress response requires the normal function of this pathway. This regulation of H2A.Z degradation by acetylation is a previously unrecognised aspect of gene regulation.
2018-04-05 | GSE97822 | GEO
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.
2015-11-04 | E-GEOD-35430 | biostudies-arrayexpress
Project description:Affinity Purification Mass Spectrometry (AP-MS) of Drosophila ovaries expressing an H2A.Z-FlagHA transgene to identify interacting partners of H2A.Z to elucidate potential maternally supplied histone chaperones that deposit H2A.Z on the transcription start site (TSS).
2022-02-15 | PXD029061 | Pride
Project description:The histone variant H2A.Z plays key roles in gene expression, DNA repair, and centromere function. H2A.Z deposition is controlled by SWR-C chromatin remodeling enzymes that catalyze the nucleosomal exchange of canonical H2A with H2A.Z. Here we report that acetylation of histone H3 lysine 56 (H3-K56Ac) alters the substrate specificity of SWR-C, leading to promiscuous dimer exchange where either H2A.Z or H2A can be exchanged from nucleosomes. This result is confirmed in vivo, where genome-wide analysis demonstrates widespread decreases in H2A.Z levels in yeast mutants with hyperacetylated H3K56. Our work also suggests that a conserved SWR-C subunit may function as a M-bM-^@M-^\lockM-bM-^@M-^] that prevents removal of H2A.Z from nucleosomes. Our study identifies a histone modification that regulates a chromatin remodeling reaction and provides insights into how histone variants and nucleosome turnover can be controlled by chromatin regulators. H2A.Z ChIP seq experiments in mutants with constitutive H3K56ac
2013-04-15 | E-GEOD-43935 | biostudies-arrayexpress
Project description:The histone variant H2A.Z has been implicated in nucleosome exchange, transcriptional activation and Polycomb repression. However, the relationships among these seemingly disparate functions remain obscure. We mapped H2A.Z genome-wide in mammalian ES cells and neural progenitors. H2A.Z is deposited promiscuously at promoters and enhancers, and correlates strongly with H3K4 methylation. Accordingly, H2A.Z is present at poised promoters with bivalent chromatin and at active promoters with H3K4 methylation, but is absent from stably repressed promoters that are specifically enriched for H3K27 trimethylation. We also characterized post-translational modification states of H2A.Z, including a novel species dually-modified by ubiquitination and acetylation that is enriched at bivalent chromatin. Our findings associate H2A.Z with functionally distinct genomic elements, and suggest that post-translational modifications may reconcile its contrasting locations and roles. Examination of histone variant, histone modifications and transcription machinery in 3 cell types
2012-07-19 | E-GEOD-39237 | biostudies-arrayexpress
Project description:The histone variant H2A.Z has been implicated in the regulation of gene expression, and in plants antagonizes DNA methylation. Here we ask whether a similar relationship exists in mammals, using a mouse lymphoma model, where chromatin states can be monitored during tumorigenesis. Using native ChIP-on-chip, we found a progressive depletion of H2A.Z around transcriptional start sites (TSSs) during cell state transformations. In addition, we found that H2A.Z and DNA methylation are anti-correlated around TSSs in wild-type and Myc-transformed cells. Surprisingly, approximately 30% of genes show a redistribution of H2A.Z from around TSSs to bodies of active genes during oncogenesis but not before, and these changes are accompanied by DNA methylation changes in the opposite direction. Our results suggest that antagonism between H2A.Z deposition and DNA methylation is a conserved feature of eukaryotic genes, and that transcription-coupled H2A.Z changes may play a role in cancer initiation and progression. Keywords: Chromatin affinity-purification on microarray
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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.
2015-11-04 | GSE35430 | GEO