Chromatin in eukaryotic nuclei is organized at multiple scales, from individual nucleosomes to specific loops between regulatory sequences, to the folding of large genomic regions into topological domains and segregation of whole chromosomes into territories. Many of the chromatin proteins that regulate this architecture, including the essential Polycomb Group (PcG) proteins, are themselves organized into subnuclear structures. Deciphering mechanistic links between protein organization and genome architecture requires precise description and mechanistic perturbations of both. Using super-resolution microscopy, we characterized the nanoscale organization of PcG proteins in Drosophila cells and find hundreds of small protein clusters, distinct from the large PcG bodies present in just a few copies per cell that have been the focus of previous investigations. We manipulated PcG clusters either by disrupting the polymerization activity of the conserved Sterile Alpha Motif (SAM) of the PcG protein Polyhomeotic (Ph) or increasing Ph levels in Drosophila S2 cells. Disrupting clustering using Ph SAM mutations disrupts chromatin interactions on scales from 50kb to 13Mb while increasing Ph levels increases both cluster number and long range chromatin interactions. RNA-seq and qPCR indicate that both perturbations also alter expression levels of many genes. Molecular simulations suggest a model in which PcG cluster formation on chromatin is governed by the kinetics of association between Ph SAMs and PcG cluster size is bounded by the affinity and occupancy of chromatin binding sites. Our results suggest that nanoscale organization of PcG proteins into small, abundant clusters on chromatin through the polymerization activity of Ph SAM shapes genome architecture by mediating numerous long-range chromatin interactions. Overall design: Two biological replicates of three RNA-seq samples from S2 cells, cells overexpresing wild-type Ph, and cells overexpressing polymerization defective Ph-ML
Chromatin topology is coupled to Polycomb group protein subnuclear organization.
Cell line, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Choice of binding sites for CTCFL compared to CTCF is driven by chromatin and by sequence preference.
Cell line, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Differential roles for MBD2 and MBD3 at methylated CpG islands, active promoters and binding to exon sequences.
Specimen part, Cell line
View SamplesThe heterogeneous collection of NuRD complexes can be grouped into the MBD2 or MBD3 containing complexes MBD2-NuRD and MBD3-NuRD. MBD2 is known to bind to methylated CpG sequences in vitro in contrast to MBD3. Although functional differences have been described, a direct comparison of MBD2 and MBD3 in respect to genome-wide binding and function has been lacking. Here we show when depleting cells for MBD2, the MBD2 bound genes increase their activity, whereas MBD2 plus MBD3 bound genes reduce their activity. Most strikingly, MBD3 is enriched at active promoters, whereas MBD2 is bound at methylated promoters and enriched at exon sequences of active genes. This suggests a functional connection between MBD2 binding to chromatin and splicing.
Differential roles for MBD2 and MBD3 at methylated CpG islands, active promoters and binding to exon sequences.
Cell line
View SamplesGene expression is tightly linked to histone acetylation on lysine residues that can be recognized by bromodomains. The testis-specific bromodomain protein tBRD-1 is essential for male fertility and might act as a co-factor of testis-specifc TAFs. Here, we perform microarray analyses and demonstrate that tBRD-1 selectively controls gene expression in male germ cells
tBRD-1 selectively controls gene activity in the Drosophila testis and interacts with two new members of the bromodomain and extra-terminal (BET) family.
Specimen part
View SamplesThe high-mobility-group (HMG) proteins are the most abundant non-histone chromatin-associated proteins. Here we deciphered the role of the high mobility group AT-hook protein 2 (HMGA2) during lung development by analyzing the lung of Hmga2 deficient mice (Hmga2-/-).We found that Hmga2 is expressed in the mouse embryonic lung at the distal airways. Analysis of Hmga2-/- mice showed that Hmga2 is required for proper cell proliferation and distal epithelium differentiation during embryonic lung development. Hmga2 knockout (KO) led to enhanced canonical WNT signaling due to an increased expression of secreted WNT glycoproteins Wnt2b, Wnt7b and Wnt11 as well as a reduction of the WNT signaling antagonizing proteins GATA6 (GATA binding protein 6) and FZD2 (frizzled homolog 2).
Hmga2 is required for canonical WNT signaling during lung development.
Specimen part
View SamplesHyperglycemia can contribute to the detrimental effects of diabetes in the vasculature.
Elevated Glucose Levels Promote Contractile and Cytoskeletal Gene Expression in Vascular Smooth Muscle via Rho/Protein Kinase C and Actin Polymerization.
Specimen part
View SamplesThe right ventricle (RV) differs in several aspects from the left ventricle (LV) including its embryonic origin, physiological role and anatomical design. In contrast to LV hypertrophy, little is known about the molecular circuits, which are activated upon RV hypertrophy (RVH). We established a highly reproducible model of RVH in mice using pulmonary artery clipping (PAC), which avoids detrimental RV pressure overload and thus allows long-term survival of operated mice. Magnetic resonance imaging revealed pathognomonic changes with striking similarities to human congenital heart disease- or pulmonary arterial hypertension- patients. Comparative, microarray based transcriptome analysis of right- and left-ventricular remodeling identified distinct transcriptional responses to pressure-induced hypertrophy of either ventricle, which were mainly characterized by stronger transcriptional responses of the RV compared to the LV myocardium. Hierarchic cluster analysis revealed a RV- and LV-specific pattern of gene activity after induction of hypertrophy, however, we did not find evidence for qualitatively distinct regulatory pathways in RV compared to LV. Data mining of nearly three thousand RV-enriched genes under PAC disclosed novel potential (co)-regulators of long-term RV remodeling and hypertrophy. We reason that specific inhibitory mechanisms in RV restrict excessive myocardial hypertrophy and thereby contribute to its vulnerability to pressure overload.
Identification of right heart-enriched genes in a murine model of chronic outflow tract obstruction.
Sex, Age, Specimen part
View SamplesExpression profiles of 917 pathway repoter genes were determined by AmpliSeq-RNA in primary human hepatocytes treated with Diclofenac and a test compound 3 hours after treatment. Overall design: Vehicle control, diclofenac, and three doses of the test compound (small-molecule neurotransmitter receptor antagonist) were applied to three primary cell lines, with three biological replicates in each group. In some treatment groups read-outs were only available for two samples. All together 41 samples were profiled.
Pathway reporter genes define molecular phenotypes of human cells.
No sample metadata fields
View SamplesGene expression studies from hematopoietic stem cell (HSC) populations purified to variable degrees have defined a set of stemness genes. The present study describes the construction and comparative molecular analysis of l-phage cDNA libraries from highly purified primitive HSCs (PHSCs) which retained their long term repopulating activities (LTRAs), and from maturing HSCs (MHSCs) which were largely depleted of LTRAs. Library inserts were amplified and tagged by a T7 RNA polymerase promoter and used to generate biotinylated cRNA for Microarray hybridization. Microarray analysis of the libraries confirmed previous results but also revealed an unforseen preferential expression of translation and metabolism associated genes in the PHSCs. Therefore these data indicate that HSCs are quiescent only in regard of proliferative activities, but are in a state of readiness to provide the metabolic and translational activities required following induction of proliferation by factors which induce differentiation and exit from the HSC pool.
Gene expression profiles in murine hematopoietic stem cells revisited: analysis of cDNA libraries reveals high levels of translational and metabolic activities.
No sample metadata fields
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