Nucleosome occupancy profiles in young and old mouse liver [MNase-Seq]
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Irina Bochkis
PROVIDER: E-GEOD-58005 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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2015-03-02 | E-GEOD-58012 | biostudies-arrayexpress
Project description:Nucleosomal DNA was prepared using Simple ChIP Enzymatic Chromatin IP Kit according to manufacturer’s instruction. Briefly, Nuclei were isolated from purified Ter119 negative or in vitro cultured erythroblasts. Cross-linked native chromatin was then digested with MNase into mononucleosomal DNA. Sequencing libraries were generated from nucleosomal DNA, and sequencing was carried out using the Illumina system according to the manufacturer’s specification. In this study, we purified chromatin from in vitro cultured mouse fetal liver erythroblasts on day 0, day 1, and day 2. The chromatins were digested by micrococcal nuclease to make mononucleosomal products, which were further analyzed by next generation sequencing analysis. We aim to determine the dynamic changes of nucleosome during terminal erythropoiesis.
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Project description:Here we have employed chromatin immunoprecipitation combined with deep sequencing to map and compare PPARM-NM-3 binding in in vitro differentiated primary mouse adipocytes isolated from epididymal, inguinal, and brown adipose tissues. While these PPARM-NM-3 binding profiles are overall similar, there are clear depot-selective binding sites. Most PPARM-NM-3 binding sites previously mapped in 3T3-L1 adipocytes can also be detected in primary adipocytes, but there are a large number of PPARM-NM-3 binding sites that are specific to the primary cells, and these tend to be located in closed chromatin regions in 3T3-L1 adipocytes. The depot-selective binding of PPARM-NM-3 is associated with highly depot-specific gene expression. This indicates that PPARM-NM-3 plays a role in the induction of genes characteristic of different adipocyte lineages and that preadipocytes from different depots are differentially preprogrammed to permit PPARM-NM-3 lineage-specific recruitment even when differentiated in vitro. Examination of PPARM-NM-3 binding in in vitro differentiatied adipocytes isolated from three different adipose depots.
2012-10-11 | E-GEOD-41481 | biostudies-arrayexpress
Project description:Background: Repair of DNA damage requires chromatin remodeling to permit removal of the lesions. How nucleosomes are remodelled to initiate repair of DNA damage remains largely unknown. Here, we describe how chromatin is altered during repair of UV-induced DNA damage at the level of the linear organisation of nucleosomes. Results: Using MNase-seq, we identified a subset of nucleosomes in the genome that are remodelled in UV-damaged wild-type yeast cells. We mapped the genomic location of these nucleosomes, showing that they contain the histone variant H2A.Z. The remodelling observed is consistent with histone exchange or eviction at these positions. This depends on the yeast SWI/SNF global genome nucleotide excision repair (GG-NER) chromatin-remodelling complex. Remarkably, we found that in the absence of DNA damage, the GG-NER complex occupies chromatin at nucleosome free regions separating adjacent nucleosomes. This establishes the nucleosome structure at these genomic locations, which we refer to as GG-NER complex binding sites (GCBS’s). We observed that these sites are frequently located precisely at certain boundary regions that delineate chromasomally interacting domains (CIDs). These boundaries define chromosomal domains of higher-order nucleosome-nucleosome interaction. We demonstrate that the GG-NER complex redistributes following remodelling of these nucleosomes after DNA damage taking up genomic positions located within the CIDs. This permits the efficient removal of DNA damage at these sites. Conclusions: We argue that organising DNA repair in the genome as described may define origins of DNA repair that greatly reduces the genomic search space for DNA damage recognition, thus ensuring the efficient repair of damage in chromatin.
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Project description:"Master" transcription factors are the gatekeepers of lineage identity. As such, they have been a major focus of efforts to manipulate cell fate for therapeutic purposes. The ETS transcription factor PU.1 has a potent ability to confer macrophage phenotypes on cells already committed to a different lineage, but how it overcomes the presence of other master regulators is not known. The nuclear receptor PPARM-NM-3 is the master regulator of the adipose lineage, and its genomic binding pattern is well characterized in adipocytes. Here, we show that when expressed at macrophage levels in mature adipocytes, PU.1 bound a large fraction of its macrophage sites, where it induced chromatin opening and the expression of macrophage target genes. Strikingly, PU.1 markedly reduced the genomic binding of PPARM-NM-3 without changing its abundance. PU.1 expression repressed genes with nearby adipocyte-specific PPARM-NM-3 binding sites, while a common macrophage-adipocyte gene expression program was retained. Together, these data reveal unexpected lability within the adipocyte PPARM-NM-3 cistrome and show that even in terminally differentiated cells, PU.1 can remodel the cistrome of another master regulator. ChIP-seq was performed on 3T3-L1 adipocytes from two treatment groups: (1) adipocytes transduced with a control adenovirus expressing beta-galactosidase (LACZ-Ads) and (2) adipocytes transduced with an adenovirus expressing full-length murine PU.1 cDNA (PU.1-Ads). Nuclear lysates from each group were used for PPARg ChIP. For PU.1-Ads, PU.1 ChIP was also performed. To generate chromatin for ChIP-seq, DNA from three immunoprecipitations per condition was pooled. This process was repreated from a second set of L1 adipocytes to generate two biological replicates for sequencing. Genomic input DNA was sequenced from the first biological replicate only.
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