A SNF2 protein targets variable copy number repeats and thereby influences allele-specific expression
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus Homo sapiens
PROVIDER: GSE22162 | GEO | 2010/11/02
SECONDARY ACCESSION(S): PRJNA127699
REPOSITORIES: GEO
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Project description:ATRX is an X-linked gene of the SWI/SNF family whose role in vivo is currently unknown. Mutations in ATRX cause syndromal mental retardation. ATRX binds to tandem repeat (TR) sequences both in heterochromatin (e.g. telomeres) and euchromatin. Genes associated with these TRs can be dysregulated when ATRX is mutated and the degree to which their expression changes is determined by the size of the TR, producing skewed allelic expression. This explains the nature of the affected genes, the variable phenotypes seen with identical ATRX mutations and also illustrates a new mechanism underlying variable penetrance. Many of the TRs in ATRX targets are G-rich and predicted to form non-B DNA structures (including G quadruplex) in vivo. We have shown that ATRX binds G quadruplex structures in vitro suggesting a mechanism by which ATRX may play a role in various nuclear processes and how this is perturbed when ATRX is mutated. 4 Human Erythroblast, 1 HEP3B and 1 Fibroblast ChIP-ChIP Sample For ChIP-Seq: one human erythroblasts, one mouse ES, one human erythroblast reference Sample, and one mouse ES input reference Sample.
2010-11-02 | E-GEOD-22162 | biostudies-arrayexpress
Project description:Mucins are a large family of heavily O-glycosylated proteins that cover all mucosal surfaces and constitute the major macromolecules in most body fluids. Mucins can form aggregated networks and bundles that serve as a barrier, but also assist in containing, feeding, clearing and replenishing microorganisms. Mucins are primarily defined by their variable tandem repeat (TR) domains that are densely decorated with different O-glycan structures in distinct patterns, and these arguably convey much of the informational content of mucins. However, the O-glycodomains have long evaded detailed structural and functional exploration. Here, we developed a cell-based platform for the display and production of human TR O-glycodomains (~200 amino acids) with tunable structures and patterns of O-glycans using membrane-bound and secreted constructs expressed in glycoengineered HEK293 cells. The expressed mucin TRs revealed surprisingly high fidelity in complete decoration with designed O-glycan structures, which enabled intact mass analysis with the simplest glycoforms. Availability of defined mucin TR O-glycodomains advances experimental studies into the versatile role of mucins at the interface with pathogenic microorganisms and the microbiome, and sparks new strategies for molecular dissection of specific roles of adhesins, glycoside hydrolases, glycopeptidases, viruses and other interactions with mucin TRs as highlighted by examples.
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Project description:The genome consists of non-B-DNA structures such as G-quadruplexes (G4) that are involved in the regulation of genome stability and transcription. Telomeric-repeat containing RNA (TERRA) is capable of folding into G-quadruplex and interacting with chromatin remodeler ATRX. Here we show that TERRA modulates ATRX occupancy on repetitive sequences and over genes, and maintains DNA G-quadruplex structures at TERRA target and non-target sites in mouse embryonic stem cells. TERRA prevents ATRX from binding to subtelomeric regions and represses H3K9me3 formation. G4 ChIP-seq reveals that G4 abundance decreases at accessible chromatin regions, particularly at transcription start sites (TSS) after TERRA depletion; such G4 reduction at TSS is associated with elevated ATRX occupancy and differentially expressed genes. Loss of ATRX alleviates the effect of gene repression caused by TERRA depletion. Immunostaining analyses demonstrate that knockdown of TERRA diminishes DNA G4 signals, whereas silencing ATRX elevates G4 formation. Our results uncover an epigenetic regulation by TERRA that sequesters ATRX and preserves DNA G4 structures.
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Project description:Thyroid hormone receptors (TRs) are hormone-regulated transcription factors that regulate a diverse array of biological activities, including metabolism, homeostasis, and development. TRs also serve as tumor suppressors, and aberrant TR function (via mutation, deletion, or altered expression) is associated with a spectrum of both neoplastic and endocrine diseases. A particularly high frequency of TR mutations has been reported in renal clear cell carcinoma (RCCC) and in hepatocellular carcinoma (HCC). We have shown that HCC-TR mutants regulate only a fraction of the genes targeted by wild-type TRs, but have gained the ability to regulate other, unique, targets. We have suggested that this altered gene recognition may contribute to the neoplastic phenotype. Here, to determine the generality of this phenomenon, we examined a distinct set of TR mutants associated with RCCCs. We report that two different TR mutants, isolated from independent RCCC tumors, possess greatly expanded target gene specificities that extensively overlap one another, but only minimally overlap that of the WT-TRs, or those of two HCC-TR mutants. Many of the genes targeted by either or both RCCC-TR mutants have been previously implicated in RCCC, and include a series of metallothioneins, solute carriers, and genes involved in glycolysis and energy metabolism. We propose that TR mutations from RCCC and HCC are likely to play tissue-specific roles in carcinogenesis, and that the divergent target gene recognition patterns of TR mutants isolated from the two different types of tumors arises from different selective pressures during development of RCCC versus HCC. Gene expression was analyzed in HepG2 transformants expressing ectopic wildtype THRA, wildtype THRB, HCC-TR mutants ?? and ?N, and RCCC-TR mutants 6? and 15? using Affymetrix Human Gene 1.0 ST arrays in the presence or absence of T3. Each HepG2 transformant was assayed in triplicate.
2011-05-10 | E-GEOD-29159 | biostudies-arrayexpress
Project description:We analyze the contribution of ATRX, DAXX and HIRA to the chromatin accessibility at G-quadruplex in mESC We analyze the contribution of ATRX and ESET to the chromatin accessibility at G-quadruplex in mESC
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Project description:The G-quadruplex is an alternative DNA structural motif that is considered to be functionally important in the mammalian genome. Herein, we address the hypothesis that G-quadruplex structures can exist within double-stranded genomic DNA using a G-quadruplex-specific probe. An engineered antibody is employed to enrich for DNA containing G-quadruplex structures, followed by deep sequencing to detect and map G-quadruplexes at high resolution in genomic DNA from human breast adenocarcinoma cells. Our high sensitivity structure-based pull-down strategy enables the isolation of genomic DNA fragments bearing a single as well as multiple G-quadruplex structures. Stable G-quadruplex structures are found in sub-telomeres, gene bodies and gene regulatory regions. For a sample of identified target genes, we show that G-quadruplex stabilizing ligands can modulate transcription. These results confirm the existence of G-quadruplex structures and their persistence in human genomic DNA. Four independent libraries have been enriched in DNA G-quadruplex structures using a G-quadruplex-specific probe. One genomic input library was sequenced as control. Deep-sequencing of these libraries allowed the mapping of G-quadruplexes on the genome.
2013-05-08 | E-GEOD-45241 | biostudies-arrayexpress
Project description:Thyroid hormone receptors (TRs) are hormone-regulated transcription factors that regulate a diverse array of biological activities, including metabolism, homeostasis, and development. TRs also serve as tumor suppressors, and aberrant TR function (via mutation, deletion, or altered expression) is associated with a spectrum of both neoplastic and endocrine diseases. A particularly high frequency of TR mutations has been reported in renal clear cell carcinoma (RCCC) and in hepatocellular carcinoma (HCC). We have shown that HCC-TR mutants regulate only a fraction of the genes targeted by wild-type TRs, but have gained the ability to regulate other, unique, targets. We have suggested that this altered gene recognition may contribute to the neoplastic phenotype. Here, to determine the generality of this phenomenon, we examined a distinct set of TR mutants associated with RCCCs. We report that two different TR mutants, isolated from independent RCCC tumors, possess greatly expanded target gene specificities that extensively overlap one another, but only minimally overlap that of the WT-TRs, or those of two HCC-TR mutants. Many of the genes targeted by either or both RCCC-TR mutants have been previously implicated in RCCC, and include a series of metallothioneins, solute carriers, and genes involved in glycolysis and energy metabolism. We propose that TR mutations from RCCC and HCC are likely to play tissue-specific roles in carcinogenesis, and that the divergent target gene recognition patterns of TR mutants isolated from the two different types of tumors arises from different selective pressures during development of RCCC versus HCC.
2011-05-10 | GSE29159 | GEO
Project description:Rif1 regulates replication timing and repair of double-stranded DNA breaks. Using Chromatin-immunoprecipitation-Sequencing method, we have identified 35 high-affinity Rif1 binding sites in fission yeast chromosomes. Binding sites, preferentially located to the vicinity of dormant origins, tended to contain at least two copies of a conserved motif, CNWWGTGGGGG, and base substitution within these motifs resulted in complete loss of Rif1 binding and activation of late-firing or dormant origins located as far as 50 kb away. We show that Rif1 binding sites adopt G-quadruplex-like structures in vitro in a manner dependent on the conserved sequence as well as on other G-tracts, and that the purified Rif1 preferentially binds to this structure. These results suggest that Rif1 recognizes and binds to G-quadruplex-like structures at selected intergenic regions to generate local chromatin structures that may exert a long-range suppressive effects on origin firing. ChIP-Seq profiles of Rif1 and DNA replicaiton (BrdU-incorporation) vs Input in wildt type, rap1∆, taz1∆, Rif1BS mutants and rif1∆
2015-09-10 | E-GEOD-65293 | biostudies-arrayexpress
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Project description:We previously demonstrated by genomic and bioinformatical approaches that human macrophage (MΦ) activation is best described by a spectrum model (Xue et al, Immunity, 2014). MΦ integrate exogenous input signals on transcriptional level in a unique fashion to generate specific functional programs, enabling the plasticity in disease-related pathophysiologies. Such versatile responsiveness requires fast changes of transcription mediated by transcriptional regulators (TRs) or epigenomic changes. To better understand the principles of this regulation during human MΦ activation, we assessed histone modifications including H3K4me1, H3K4me3, H3K27me3, and H3K27Ac by ChIP-sequencing allowing us to characterize the functional state of promoters (active, poised, repressed) and enhancers (active, inactive, intermediate). Using transcriptome data from our MΦ spectrum model, we generated a co-regulation network of all TRs. Next, we overlaid epigenomic information and transcriptional changes of major TRs over time onto the TR network. We observed that input signals like IFNγ or TNFα induce a specific network of TRs that are transcriptionally regulated themselves, the combination of regulated TRs changes over time with a boost of transcriptional regulation of dozens of TRs 4 to 12 hrs post input signal exposure, almost all TRs within the network show active promoters, even if the TR itself is not expressed, and similar results are obtained for enhancers with open or at least intermediated states. These findings strongly suggest that in MΦ, the TR-defined cellular â??switch panelâ?? is always accessible thereby allowing MΦ to quickly respond to the diverse input signal repertoire from the environment. Epigenetic analysis of promoter and enhancer sites in primary human macrophage subtypes and correlation to RNA-seq expression data
2016-02-28 | E-GEOD-66594 | biostudies-arrayexpress