The goal of the project was to isolate single miRNA-expressing cells labelled by GFP reporter genes under the control of endogenous miRNA promoters and analyze expression levels of miRNA target genes in these cells. GFP-positive miRNA-expressing cells and GFP-negative cells from the rest of the embryos were purified at the same developmental stage to the cellular resolution using fluorescent activated cell sorting (FACS). Focus was on regulation by miR-206 and miR-133 in the developing somites and miR-124 in the developing central nervous system. Comparison of wild-type embryos and those lacking miRNAs revealed predicted
Coherent but overlapping expression of microRNAs and their targets during vertebrate development.
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View SamplesComparison between [gar-] and [GAR+] samples of the W303 background grown in 2% glucose.
No associated publication
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Chromatin structure and gene expression programs of human embryonic and induced pluripotent stem cells.
Cell line
View SamplesKnowledge of both the global chromatin structure and the gene expression programs of human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells should provide a robust means to assess whether the genomes of these cells have similar pluripotent states. Recent studies have suggested that ES and iPS cells represent different pluripotent states with substantially different gene expression profiles. We describe here a comparison of global chromatin structure and gene expression data for a panel of human ES and iPS cells. Genome-wide maps of nucleosomes with histone H3K4me3 and H3K27me3 modifications indicate that there is little difference between ES and iPS cells with respect to these marks. Gene expression profiles confirm that the transcriptional programs of ES and iPS cells show very few consistent differences. Although some variation in chromatin structure and gene expression was observed in these cell lines, these variations did not serve to distinguish ES from iPS cells.
Chromatin structure and gene expression programs of human embryonic and induced pluripotent stem cells.
Cell line
View SamplesFat tissue was resected during gastric bypass surgery for management of obesity. All subjects had fasted at least 10 hours before surgery. Subjects with malignancies were excluded. No subjects were taking thiazolidinediones or steroids. None had fasting plasma glucose levels over 120 mg/ dl. One half to 10 g of abdominal subcutaneous (external to the fascia superficialis), mesenteric, and greater omental fat were obtained from each subject. The tissue was collected in Hanks balanced salt solution with bicarbonate, penicillin, and gentamicin. Fat tissue was minced and then digested in HBSS containing 1 mg/ml collagenase and 7.5% fetal bovine serum in a 37*C shaking water bath until fragments were no longer visible and the digest had a milky appearance. Digests were filtered and centrifuged at 800xG for 10 min. The digests were treated with an erythrocyte lysis buffer. Cells were plated in 1:1 Dulbeccos modified Eagles medium:Hams F12 that contained 10% fetal bovine serum and antibiotics at a density of 4 x 104 cells/cm2. After 18 hours cultures were trypsinized until 95% of cells were detached (leaving endothelial cells and macrophages behind) and re-plated. Macrophages were rare (less than 5 per 106 cells, as assessed by phase contrast microscopy) in the re-plated cultures, irrespective of fat depot origin. Plating medium was changed every 2 days until confluence. For differentiation, preadipocytes were treated for 30 days with plating medium (without serum) enriched with 100 nM dexamethasone, 500 nM human insulin, 200 pM triiodothyronine, 0.5 *M rosiglitazone, antibiotics, and 540 *M methylisobutylxanthine (removed after 2 days). Higher rosiglitazone and insulin concentrations did not further enhance differentiation. Medium was changed every 2 days. For the final 2 days, differentiation medium was removed and cells were cultured in plating medium without serum. Undifferentiated preadipocytes were maintained in plating medium until confluence, when serum was removed for 2 days. For telomerase-expressing clones, preadipocytes were isolated and when cells had undergone 7 population doublings, they were transduced with a retrovirus containing the plasmid, pBABE-hTERT-Hygro. This vector expresses the human telomerase reverse transcriptase component (hTERT) driven by the Moloney murine leukemia virus long terminal repeat promoter and a hygromycin resistance sequence driven by the SV40 promoter. The 3 abdominal subcutaneous and 3 omental stably transduced, hygromycin-resistant clones capable of achieving confluence fastest were selected from 38 subcutaneous and 42 omental clones. Telomerase activity in these clones was verified using a PCR-based telomere repeat amplification protocol. RNA was isolated from preadipocytes by the Trizol method. RNA samples were labeled using the standard one-cycle Affymetrix GeneChip Eukaryotic Target Labeling Assay for Expression Analysis. Samples were hybridized for 16 hours at 45 C and 60 rpm, washed and stained according to the standard Affymetrix Antibody Amplification for Eukaryotic Targets protocol, and scanned at 488 nm. Images were quantified and linearly scaled using Affymetrix GeneChip Operating Software 1.1 using default analysis settings.
Identification of depot-specific human fat cell progenitors through distinct expression profiles and developmental gene patterns.
No sample metadata fields
View SamplesMLL-fusion proteins are potent inducers of cancer in hematopoietic cells, where they are known to cause changes in global gene expression. How MLL-fusion proteins interact with the genome has not been established, so we have limited understanding of the pathway by which these proteins generate aberrant gene expression programs. Here we describe how the MLL-AF4 protein occupies the genome in human leukemia cells and its striking effects on chromatin states. We find that the MLL-AF4 fusion protein selectively occupies regions of the genome that contain developmental regulatory genes important for hematopoietic stem cell identity and self-renewal. These MLL-AF4 bound regions have grossly altered chromatin structure, with histone modifications catalyzed by Trithorax Group (TrxG) proteins and Dot1 extending across unusually large domains. This indicates that a key feature of MLL-associated leukemogenesis is aberrant targeting of chromatin modifiers to regions of the genome controlling hematopoietic development. Our results define the direct targets of the MLL-fusion protein, reveal the global role of epigenetic misregulation in leukemia, and identify new targets for therapeutic intervention in human cancer.
Aberrant chromatin at genes encoding stem cell regulators in human mixed-lineage leukemia.
No sample metadata fields
View SamplesPharmacogenomic identification of targets for adjuvant therapy with the topoisomerase poison camptothecin.
Pharmacogenomic identification of targets for adjuvant therapy with the topoisomerase poison camptothecin.
No sample metadata fields
View SamplesMicroarrays were used to determine relative global gene expression changes upon introduction of EMT-inducing or control vectors.
Core epithelial-to-mesenchymal transition interactome gene-expression signature is associated with claudin-low and metaplastic breast cancer subtypes.
Specimen part
View SamplesScreens for agents that specifically kill epithelial cancer stem cells (CSCs) have not been possible due to the rarity of these cells within tumor cell populations and their relative instability in culture. We describe here an approach to screening for agents with epithelial CSC-specific toxicity. We implemented this method in a chemical screen and discovered compounds showing selective toxicity for breast CSCs. One compound, salinomycin, reduces the proportion of CSCs by >100-fold relative to paclitaxel, a commonly used breast cancer chemotherapeutic drug. Treatment of mice with salinomycin inhibits mammary tumor growth in vivo and induces increased epithelial differentiation of tumor cells. In addition, global gene expression analyses show that salinomycin treatment results in the loss of expression of breast CSC genes previously identified by analyses of breast tissues isolated directly from patients. This study demonstrates the ability to identify agents with specific toxicity for epithelial CSCs
Identification of selective inhibitors of cancer stem cells by high-throughput screening.
Specimen part
View SamplesThe molecular chaperone HSP90 aids the maturation of a diverse but select set of metastable protein clients, many of which are key to a variety of signal transduction pathways. HSP90 function has been best investigated in animal and fungal systems, where inhibition of the chaperone has exceptionally diverse effects, ranging from reversing oncogenic transformation to facilitating the acquisition of drug resistance. Inhibition of HSP90 in the model plant Arabidopsis thaliana uncovers novel morphologies dependent on normally cryptic genetic variation and increases stochastic variation inherent to developmental processes. The biochemical activity of HSP90 is strictly conserved between animals and plants. However, the substrates and pathways dependent on HSP90 in plants are poorly understood. Progress has been impeded by reliance on light-sensitive HSP90 inhibitors due to redundancy in the A. thaliana HSP90 gene family. Here we present phenotypic and genome-wide expression analyses of A. thaliana with constitutively reduced HSP90 levels achieved by RNAi targeting. HSP90 reduction affects a variety of quantitative life-history traits, including flowering time and total seed set, and decreases developmental stability. Further, by quantitative analysis of morphological phenotypes, we demonstrate that HSP90-reduction increases phenotypic diversity in both seedlings and adult plants. Several morphologies are synergistically affected by HSP90 and growth temperature. Genome-wide expression analyses also suggest a central role for HSP90 in the genesis and maintenance of plastic responses. The expression results are substantiated by examination of the response of HSP90-reduced plants to attack by caterpillars of the generalist herbivore Trichoplusia ni. HSP90 reduction potentiates a more robust herbivore defense response. In sum, we propose that HSP90 exerts global effects on the environmental responsiveness of plants to many different stimuli. The comprehensive set of HSP90-reduced lines described here is a vital instrument to further examine the role of HSP90 as a central interface between organism, development, and environment.
Phenotypic diversity and altered environmental plasticity in Arabidopsis thaliana with reduced Hsp90 levels.
Age, Specimen part
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