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Mus musculus
9 Downloadable Samples
Affymetrix Mouse Gene 1.0 ST Array (mogene10st)
Description
Red meat consumption is associated with an increased colon cancer risk. Heme, present in red meat, injures the colon surface epithelium by luminal cytotoxicity and reactive oxygen species. This surface injury is compensated by hyperproliferation and hyperplasia of crypt cells, which was induced by a changed surface to crypt signalling as recently described. It is unknown whether the change in signaling is caused by cytotoxic stress and/or by oxidative stress, as these processes were never studied separately. Therefore, the aim of this study was to determine the possible differential effects of dietary heme on these luminal stressors and their impact on the colonic mucosa after 2, 4, 7 and 14 days of heme feeding. Mice received a purified humanized control diet or this diet supplemented with 0.2 mol heme/g. Oxidative stress was measured as Thiobarbituric Acid Reactive Substances (TBARS) in fecal water. Cytotoxicity of fecal water was quantified with a bioassay. Epithelial cell proliferation was determined by Ki67 immunohistochemistry and mucosal responses were further studied in detail by whole genome transcriptomics. Dietary heme caused instantaneous and delayed changes in the luminal contents which were reflected in the mucosa. Instantaneous, there was an increase in reactive oxygen species leading to increased levels of lipid peroxidation products. Mucosal gene expression showed an instantaneous antioxidant response and PPAR target gene activation. After day 4 cytotoxicity of the colonic contents was increased and hyperproliferation was initiated, indicating that cytotoxicity was causal for the initiation of hyperproliferation. Several oncogenes were activated and tumor protein 53 was inhibited. In conclusion, dietary heme caused an instantaneous production of reactive oxygen species in mouse colon. A lag time was observed in the formation of cytotoxicity which coincided with the initiation hyperproliferation.
Publication Title
Dietary heme induces acute oxidative stress, but delayed cytotoxicity and compensatory hyperproliferation in mouse colon.
Sample Metadata Fields
Sex, Specimen part, Time
View Samples- Mus musculus
- 17 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
The HMG-box factor Tcf1 is required during T-cell development in the thymus and mediates the nuclear response to Wnt signals. Tcf1/ mice have previously been characterized and show developmental blocks at the CD4CD8 double negative (DN) to CD4+CD8+ double positive transition. Due to the blocks in T-cell development, Tcf1/ mice normally have a very small thymus. Unexpectedly, a large proportion of Tcf1/ mice spontaneously develop thymic lymphomas with 50% of mice developing a thymic lymphoma/leukemia at the age of 16 wk. These lymphomas are clonal, highly metastatic, and paradoxically show high Wnt signaling when crossed with Wnt reporter mice and have high expression of Wnt target genes Lef1 and Axin2. In wild-type thymocytes, Tcf1 is higher expressed than Lef1, with a predominance of Wnt inhibitory isoforms. Loss of Tcf1 as repressor of Lef1 leads to high Wnt activity and is the initiating event in lymphoma development, which is exacerbated by activating Notch1 mutations. Thus, Notch1 and loss of Tcf1 functionally act as collaborating oncogenic events. Tcf1 deficiency predisposes to the development of thymic lymphomas by ectopic up-regulation of Lef1 due to lack of Tcf1 repressive isoforms and frequently by cooperating activating mutations in Notch1. Tcf1 therefore functions as a T-cellspecific tumor suppressor gene, besides its established role as a Wnt responsive transcription factor. Thus, Tcf1 acts as a molecular switch between proliferative and repressive signals during T-lymphocyte development in the thymus.
Publication Title
The nuclear effector of Wnt-signaling, Tcf1, functions as a T-cell-specific tumor suppressor for development of lymphomas.
Sample Metadata Fields
Specimen part
View Samples
GSE18497- Homo sapiens
- 81 Downloadable Samples
- Affymetrix Human Genome U133 Plus 2.0 Array (hgu133plus2)
Description
Almost a quarter of pediatric patients with Acute Lymphoblastic Leukemia (ALL) suffer from relapses. The biological mechanisms underlying therapy response and development of relapses have remained unclear. In an attempt to better understand this phenomenon, we have analyzed 41 matched diagnosis relapse pairs of ALL patients using genomewide expression arrays (82 arrays) on purified leukemic cells. In roughly half of the patients very few differences between diagnosis and relapse samples were found (stable group), suggesting that mostly extra-leukemic factors (e.g., drug distribution, drug metabolism, compliance) contributed to the relapse. Therefore, we focused our further analysis on 20 samples with clear differences in gene expression (skewed group), reasoning that these would allow us to better study the biological mechanisms underlying relapsed ALL. After finding the differences between diagnosis and relapse pairs in this group, we identified four major gene clusters corresponding to several pathways associated with changes in cell cycle, DNA replication, recombination and repair, as well as B cell developmental genes. We also identified cancer genes commonly associated with colon carcinomas and ubiquitination to be upregulated in relapsed ALL. Thus, about half of relapses are due to selection or emergence of a clone with deregulated expression of a genes involved in pathways that regulate B cell signaling, development, cell cycle, cellular division and replication.
Publication Title
Genome-wide expression analysis of paired diagnosis-relapse samples in ALL indicates involvement of pathways related to DNA replication, cell cycle and DNA repair, independent of immune phenotype.
Sample Metadata Fields
Sex, Specimen part, Disease
View Samples- Homo sapiens
- 2 Downloadable Samples
- Affymetrix Human Genome U133 Plus 2.0 Array (hgu133plus2)
Description
Insulators are DNA elements, which prevent inappropriate interactions between the neighboring regions of the genome. They can be functionally classified as either enhancer blockers or domain barriers. CTCF (CCCTC binding factor) is the only known major insulator binding protein in the vertebrates and has been shown to bind many enhancer-blocking elements. However, it is not clear whether it plays a role in chromatin domain barriers between active and repressive domains. Here, we used ChIP-Seq to map the genome-wide binding sites of CTCF in three cell types and identified significant binding of CTCF to the boundaries of repressive chromatin domains marked by H3K27me3. Although we find an extensive overlapping of CTCF binding sites across the three cell types, its association with the domain boundaries is cell type-specific. We further show that the nucleosomes flanking CTCF binding sites are well positioned and associated with histone H2AK5 acetylation (H2AK5ac). Interestingly, we found a complementary pattern between the repressive H3K27me3 and the active H2AK5ac regions, which are separated by CTCF. Our findings indicate that CTCF may play important roles in the barrier activity of insulators and provide a resource for further investigation of the CTCF function in organizing chromatin in the human genome.
Publication Title
Global analysis of the insulator binding protein CTCF in chromatin barrier regions reveals demarcation of active and repressive domains.
Sample Metadata Fields
No sample metadata fields
View Samples- Homo sapiens
- 9 Downloadable Samples
- Affymetrix Human Genome U133 Plus 2.0 Array (hgu133plus2)
Description
Histone acetyltransferases (HATs) and deacetylases (HDACs) function antagonistically to control histone acetylation. As acetylation is a histone mark for active transcription, HATs have been associated with active and HDACs with inactive genes. We describe here genome-wide mapping of HATs and HDACs binding on chromatin and nd that both are found at active genes with acetylated histones. Our data provide evidence that HATs and HDACs are both targeted to transcribed regions of active genes by phosphorylated RNA Pol II. Furthermore, the majority of HDACs in the human genome function to reset chromatin by removing acetylation at active genes. Inactive genes that are primed by MLL-mediated histone H3K4 methylation are subject to a dynamic cycle of acetylation and deacetylation by transient HAT/HDAC binding, preventing Pol II from binding to these genes but poising them for future activation. Silent genes without any H3K4 methylation signal show no evidence of being bound by HDACs.
Publication Title
Genome-wide mapping of HATs and HDACs reveals distinct functions in active and inactive genes.
Sample Metadata Fields
Specimen part, Treatment
View Samples- Homo sapiens
- 4 Downloadable Samples
- Affymetrix Human Genome U133 Plus 2.0 Array (hgu133plus2)
Description
Histone modifications have been implicated in stem cell maintenance and differentiation. We have analyzed genome-wide changes in gene expression and histone modifications during differentiation of multipotent human primary hematopoietic stem cells/progenitor cells (HSCs/HPCs) into erythrocyte precursors. Our data indicate that H3K4me1, H3K9me1, and H3K27me1 associate with enhancers of differentiation genes prior to their activation and correlate with basal expression, suggesting that these monomethylations are involved in the maintenance of activation potential required for differentiation. In addition, although the majority of genes associated with both H3K4me3 and H3K27me3 in HSCs/HPCs become silent and lose H3K4me3 after differentiation, those that lose H3K27me3 and become activated after differentiation are associated with increased levels of H2A.Z, H3K4me1, H3K9me1, H4K20me1, and RNA polymerase II in HSCs/HPCs. Thus, our data suggest that gene expression changes during differentiation are programmed by chromatin modifications present at the HSC/HPC stage and provide a resource for enhancer and promoter identification.
Publication Title
Chromatin signatures in multipotent human hematopoietic stem cells indicate the fate of bivalent genes during differentiation.
Sample Metadata Fields
Specimen part
View Samples- Homo sapiens
- 4 Downloadable Samples
- Affymetrix Human Genome U133 Plus 2.0 Array (hgu133plus2)
Description
The positioning of nucleosomes with respect to DNA plays an important role in regulating transcription. However, nucleosome mapping has been performed for only limited genomic regions in humans. We have generated genome-wide maps of nucleosome positions in both resting and activated human CD4+ T cells by direct sequencing of nucleosome ends using the Solexa high-throughput sequencing technique.
Publication Title
Dynamic regulation of nucleosome positioning in the human genome.
Sample Metadata Fields
No sample metadata fields
View Samples- Homo sapiens
- 2 Downloadable Samples
IlluminaHiSeq2500
Description
Alterations in chromatin modifications, including DNA methylation and histone modification patterns, have been characterized under exposure of several environmental pollutants, including nickel. As with other carcinogenic metals, the mutagenic potential of nickel compounds is low and is not well correlated with its carcinogenic effects. Nickel exposure, however, is associated with alterations in chromatin modifications and related transcriptional programs, suggesting an alternative pathway whereby nickel exposure can lead to disease. To investigate the extent to which nickel exposure disrupts chromatin patterns, we profiled several histone modifications, including H3K4me3, H3K9ac, H3K27me3 and H3K9me2 as well as the insulator binding protein CTCF and the transcriptomes of control BEAS-2B cells and cells treated with nickel for 72 hours. Our results show significant alterations of the repressive histone modification H3K9me2 in nickel-exposed cells with spreading of H3K9me2 into new domains associated with gene silencing. We furthermore show that local regions of active chromatin can protect genes from nickel-induced H3K9me2 spreading. Interestingly, we show that nickel exposure selectively disrupts weaker CTCF sites, leading to spreading of H3K9me2 at these regions. These results have major implications in the understanding of how environmental carcinogens can affect chromatin dynamics and the consequences of chromatin domain disruption in disease progression. Overall design: Treat BEAS-2B cells with NiCl2 for 72 hours and compare histone modification, CTCF binding to control BEAS-2B cells to see how they regulated gene expression by RNA-seq
Publication Title
Epigenetic dysregulation by nickel through repressive chromatin domain disruption.
Sample Metadata Fields
No sample metadata fields
View Samples- Homo sapiens
- 7 Downloadable Samples
- Affymetrix Human Genome U133 Plus 2.0 Array (hgu133plus2)
Description
We compared PC3 cells with or without harboring the wild-AR construct in the growth conditions of 1nM R1881, 10nM R1881 and ethanol (the solvent for R1881). The MOCK control is PC3 cells transfected with the empty vectors.
Publication Title
Integrated expression profiling and ChIP-seq analyses of the growth inhibition response program of the androgen receptor.
Sample Metadata Fields
Cell line
View Samples- Arabidopsis thaliana
- 41 Downloadable Samples
- Illumina HiSeq 2500
Description
Cellular differentiation is associated with changes in transcript populations. Accurate quantification of transcriptomes during development can thus provide global insights into differentiation processes including the fundamental specification and differentiation events operating during plant embryogenesis. However, multiple technical challenges have limited the ability to obtain high quality early embryonic transcriptomes, namely the low amount of RNA obtainable and contamination from surrounding endosperm and seed-coat tissues. We compared the performance of three low-input mRNA sequencing (mRNA-seq) library preparation kits on 0.1 to 5 nanograms (ng) of total RNA isolated from Arabidopsis thaliana (Arabidopsis) embryos and identified a low-cost method with superior performance. This mRNA-seq method was then used to profile the transcriptomes of Arabidopsis embryos across eight developmental stages. By comprehensively comparing embryonic and post-embryonic transcriptomes, we found that embryonic transcriptomes do not resemble any other plant tissue we analyzed. Moreover, transcriptome clustering analyses revealed the presence of four distinct phases of embryogenesis which are enriched in specific biological processes. We also compared zygotic embryo transcriptomes with publicly available somatic embryo transcriptomes. Strikingly, we found little resemblance between zygotic embryos and somatic embryos derived from late-staged zygotic embryos suggesting that somatic and zygotic embryo transcriptomes are distinct from each other. In addition to the biological insights gained from our systematic characterization of the Arabidopsis embryonic transcriptome, we provide a data-rich resource for the community to explore. Overall design: mRNA-seq libraries were generated from three biological replicates of 50 Col-0 (wild type) embryos at eight different developmental stages (i.e. 8-cell/16-cell to mature green). Additionally, mRNA-seq libraries were prepared from total RNA isolated from 50 bent-cotyledon staged embryos and then diluted to 5, 1, 0.5 or 0.1 nanograms prior to library construction with three different library preparation methods.
Publication Title
The embryonic transcriptome of Arabidopsis thaliana.
Sample Metadata Fields
Specimen part, Subject
View Samples