Filters
Technology
Platform
GSE18092
Drosophila melanogaster
10 Downloadable Samples
Affymetrix Drosophila Genome 2.0 Array (drosophila2)
Description
The replication of a genomic region during S-phase can be highly dynamic between cell types that differ in transcriptome and epigenome. Replication timing has been positively correlated with several histone modifications that occur at active genes, while repressive histone modifications mark late replicating regions. This raises the question if chromatin modulates the initiating events of replication. To gain insights into this question we have studied the function of heterochromatin protein 1 (HP1), a reader of to the repressive histone lysine 9 methylation of H3, in genome-wide organization of replication. Cells with reduced levels of HP1 show an advanced replication timing of centromeric repeats in agreement with the model that repressive chromatin mediates the very late replication of large clusters of constitutive heterochromatin. Surprisingly however regions with high levels of interspersed repeats on the chromosomal arms in particular on chromosome 4 and in pericentromeric regions of chromosome 2 behave differently. Here loss of HP1 results in delayed replication timing. The fact that these regions are bound by HP1 suggests a direct effect. Thus while HP1 mediates very late replication of centromeric DNA it is also required for early replication of autosomal regions with high levels of repeats. This observation of opposing functions of HP1 suggests a model where repeat inactivation on autosomes is required for proper activation of origins of replication that fire early, while HP1 mediated repression at constitutive heterochromatin is required to ensure replication of centromeric repeats at the end of S phase.
Publication Title
Heterochromatin protein 1 (HP1) modulates replication timing of the Drosophila genome.
Sample Metadata Fields
Sex, Specimen part
View Samples- Drosophila melanogaster
- 10 Downloadable Samples
- Affymetrix Drosophila Genome 2.0 Array (drosophila2)
Description
Duplication of eukaryotic genomes during S phase is coordinated in space and time. In order to identify zones of initiation and cell-type as well as gender-specific plasticity of DNA replication, we profiled replication timing, histone acetylation and transcription throughout the Drosophila genome. We observed two waves of replication initiation with many distinct zones firing in early and multiple, less defined peaks at the end of S phase, suggesting that initiation becomes more promiscuous at the end of S phase. A comparison of different cell types revealed widespread plasticity of replication timing on autosomes. Most occur in large regions but only half coincide with local differences in transcription. In contrast to confined autosomal differences, a global shift in replication timing occurs throughout the single male X chromosome. Unlike in females, the dosage compensated X chromosome replicates almost exclusively early. This difference occurs at sites which are not transcriptionally hyperactivated, but show increased acetylation of lysine 16 of histone H4. This suggests a transcription-independent, yet chromosome-wide process related to chromatin. Importantly, H4K16ac is also enriched at initiation zones as well as early replicating regions on autosomes during S phase. Together, our data reveal novel organizational principles of DNA replication of the Drosophila genome and imply chromatin structure as a determinant of replication timing locally and chromosome-wide.
Publication Title
Chromatin state marks cell-type- and gender-specific replication of the Drosophila genome.
Sample Metadata Fields
Sex
View Samples- Mus musculus
- 6 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
Conditional ablation of Ezh2 in the neural crest lineage results in loss of the neural crest-derived mesenchymal derivatives. In this data sheet we determine gene expression analysis in Ezh2lox/lox and Wnt1Cre Ezh2lox/lox in E11.5 mouse BA1 cells.
Publication Title
Ezh2 is required for neural crest-derived cartilage and bone formation.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 7 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
This SuperSeries is composed of the SubSeries listed below.
Publication Title
Modeling of epigenome dynamics identifies transcription factors that mediate Polycomb targeting.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 7 Downloadable Samples
Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
While changes in chromatin are integral to transcriptional reprogramming during cellular differentiation, it is currently unclear how chromatin modifications are targeted to specific loci. We developed a computational model on the premise that transcription factors (TFs) direct dynamic chromatin changes during cell fate decisions. When applied to a neurogenesis paradigm, this approach predicted the TF REST as a determinant of gain of Polycomb-mediated H3K27me3 in neuronal progenitor cells. We prove this prediction experimentally by showing that the absence of REST causes loss of H3K27me3 at target promoters in trans at the same cellular state. Moreover, promoter fragments containing a REST binding site are sufficient to recruit H3K27me3 in cis, while deletion of their REST site results in loss of H3K27me3. These findings illustrate that computational modeling can systematically identify TFs that regulate chromatin dynamics genome-wide. Local determination of Polycomb activity by REST exemplifies such TF based regulation of chromatin.
Publication Title
Modeling of epigenome dynamics identifies transcription factors that mediate Polycomb targeting.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 10 Downloadable Samples
- Affymetrix Mouse Gene 1.0 ST Array (mogene10st)
Description
This SuperSeries is composed of the SubSeries listed below.
Publication Title
A chromatin-modifying function of JNK during stem cell differentiation.
Sample Metadata Fields
Specimen part, Treatment
View Samples- Mus musculus
- 10 Downloadable Samples
- Affymetrix Mouse Gene 1.0 ST Array (mogene10st)
Description
Expression profiling of from DMSO and SP600125 treated glutamatergic neurons reveals JNK target genes that are transcriptionally regulated by JNK signaling.
Publication Title
A chromatin-modifying function of JNK during stem cell differentiation.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 19 Downloadable Samples
- Affymetrix Mouse Gene 1.0 ST Array (mogene10st)
Description
Messenger RNA levels in eukaryotes are balanced by two consecutive regulatory layers. Primary, transcriptional regulation at the level of chromatin and secondary, post-transcriptional regulation of the initial transcript in the cytoplasm. Each layer is individually studied in mechanistic detail, while integration of both processes is required to quantify the individual contribution to steady-state RNA levels. Here we show that chromatin features are sufficient to model transcription rate but with different sensitivities in dividing versus post mitotic cells. In both cases chromatin derived transcript levels explains over 80% of variance in measured RNA level enabling to separate transcription from different post-transcriptional processes. By further inclusion of measurements of mRNA half-life and micro RNA expression data we identify a low quantitative contribution of RNA decay by either micro RNA or general differential turnover to final mRNA levels. Together this establishes a chromatin based quantitative model for the contribution of transcriptional and posttranscriptional processes to steady-state levels of messenger RNA.
Publication Title
Chromatin measurements reveal contributions of synthesis and decay to steady-state mRNA levels.
Sample Metadata Fields
Specimen part, Disease, Treatment, Time
View Samples- Mus musculus
- 20 Downloadable Samples
Description
Aging at the cellular level is driven by changes in gene activity and epigenetic state that are only partially understood. We performed a comprehensive epigenomic analysis of the pancreatic ß cell, key player in glucose homeostasis and diabetes, in adolescent and very old mice. Globally, we observe a general methylation drift resulting in an overall more leveled methylome, suggesting that the maintenance of highly differential methylation patterns becomes compromised with advanced age. Importantly, we discover targeted changes in the methylation status of ß cell proliferation and function genes that go against the global methylation drift, are specific to ß cells, and correlate with repression of the proliferation program and activation of metabolic regulators. These targeted alterations frequently occur at distal cis-regulator elements, and are associated with specific chromatin marks and transcription factor occupancy in young ß cells. Strikingly, we find the insulin secretory response to glucose much improved in mature ß cells in mice, as predicted by the changes in methylome and transcriptome and in contrast to the decline in function observed in aged human ß cells. Thus, aging of terminally differentiated cells in mammals is not always coupled to functional decline. Overall design: RNA-seq was done on 3 biological replicas from old and three from young beta cells. each sample originated from a pool of 5-10 mic.e H3K27me3 ChIP-seq was done with two replicas for old mice (pool of 4-7 mice) and the rest of the ChIPseq (H3K4me1, H3K27ac and young H3K27me3) was sone with one sample (pool of few mice). BIS-seq was done on one sample from a pool of 10 young mice and one sample of a pool of old mice (18-22 months old)
Publication Title
Aging-Dependent Demethylation of Regulatory Elements Correlates with Chromatin State and Improved β Cell Function.
Sample Metadata Fields
No sample metadata fields
View Samples- Mus musculus
- 6 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
Background:
Publication Title
Loss of Ezh2 promotes a midbrain-to-forebrain identity switch by direct gene derepression and Wnt-dependent regulation.
Sample Metadata Fields
Specimen part
View Samples