HaCat cell cycle experiment: During the somatic cell cycle, DNA and epigenetic modifications in DNA and histones are copied to daughter cells. DNA replication timing is tightly regulated and linked to GC content, chromatin structure, andgene transcription, but how maintenance of histone modifications relates to replication timing and transcription is less understood.The gene expression patters on HaCaT keratinocytes during the cell cycle is studied by a time series analysis of synchroniced cells sampled at 3 hour intervals. We show that genes enriched with the repressive chromatin mark histone H3 lysine 27 tri-methylation are transcribed during DNA replication . The gene expression is related to replication timing, as genes expressed during G1/S transition andearly S phase generally have higher GC content and are replicated earlier than genes expressed during late S phase. These results indicate widespread replication-dependent expression in mammals and support a role for replication in transiently activating transcription of epigenetically silenced genes.
Transcription profiling during the cell cycle shows that a subset of Polycomb-targeted genes is upregulated during DNA replication.
Specimen part, Cell line, Time
View SamplesBACKGROUND & AIMS- More frequent interaction of bacteria with the colonic epithelium is associated with ulcerative colitis (UC). The identities of all proteins which promote bacterial clearance in colonic epithelial cells are unknown. Previously, we discovered that dCAP-D3 (Chromosome Associated Protein-D3), regulates responses to bacterial infection. We examined whether CAP-D3 promotes bacterial clearance in human colonic epithelium. METHODS- Clearance of Salmonella or adherent-invasive Escherichia coli LF82 was assessed by gentamycin protection assays in HT-29 and Caco-2 cells expressing CAP-D3 shRNA. CAP-D3 levels in colonic epithelial cells from healthy and UC patient tissues were analyzed by immunoblot. RNA-sequencing identified bacterially-induced CAP-D3 target genes. The role of CAP-D3 target genes in bacterial clearance was analyzed by gentamycin protection assays, immunofluorescent staining, and by using pharmacologic inhibitors. RESULTS- CAP-D3 expression was reduced in colonic epithelial cells from UC patients with active disease. Reduction of CAP-D3 expression inhibited autophagy and decreased intracellular bacterial clearance. The components of the heterodimeric SLC7A5/SLC3A2 amino acid transporter were identified as CAP-D3 target genes; their levels increased in infected, CAP-D3 deficient cell lines and in cells from UC patients. In HT-29 cells, this resulted in earlier SLC7A5 recruitment to Salmonella-containing vacuoles, increased mTOR activity, and enhanced bacterial survival. Inhibition of SLC7A5/SLC3A2 or mTOR activity rescued the bacterial clearance defect in CAP-D3 deficient cells. CONCLUSIONS- CAP-D3 attenuates amino acid transporter transcription to promote bacterial autophagy in colon epithelial cells. CAP-D3 protein levels are decreased in patients with active UC, suggesting that CAP-D3 is a potential therapeutic target to restore mucosal homeostasis in UC patients. Overall design: Three RNA samples from 3 independent experiments including timepoints taken at 0, 0.5 and 7 hours post-infection were analyzed on a bioanalyzer for quality; one of the 0.5 hour post-infection samples was excluded at this time due to poor RNA purity. Directional, cDNA libraries made from cellular mRNAs were generated from the other 8 samples and sequenced (paired-end sequencing of 100 bp reads) in the Genomics Core at the University of Chicago on an Illumina HiSeq2000.
Chromosome-associated protein D3 promotes bacterial clearance in human intestinal epithelial cells by repressing expression of amino acid transporters.
No sample metadata fields
View SamplesThe Caenorhabditis elegans somatic gonad was the first organ to have its cell lineage determined, and the gonadal lineages of the two sexes differ greatly in their pattern of cell divisions, cell migration and cell types. Despite much study, the genetic pathways that direct early gonadal development and establish its sexual dimorphism remain largely unknown, with just a handful of regulatory genes identified from genetic screens. To help define the genetic networks that regulate gonadal development, we employed cell-specific RNA-seq. We identified transcripts present in Z1/Z4 or Z1/Z4 daughter cells in each sex at the onset of somatic gonadal sexual differentiation. For comparison, transcripts were identified in whole animals at both time points. Pairwise comparisons of samples identified several hundred gonad-enriched transcripts, including most known Z1/Z4-enriched mRNAs, and reporter analysis confirmed the effectiveness of this approach. Prior to the Z1/Z4 division few sex-biased Z1/Z4 transcripts were detectable, but less than six hours later, we identified more than 250 sex-biased transcripts in the Z1/Z4 daughters, of which about a third were enriched in the somatic gonad cells compared to cells from whole animals. This indicates that a robust sex-biased developmental program, some of it gonad-specific, initiates in these cells around the time of the first Z1/Z4 division. Cell-specific analysis also identified approximately 70 previously unannotated mRNA isoforms that are enriched in Z1/Z4 or their daughters. Our data suggest that early sex differentiation in the gonad is controlled by a relatively small suite of differentially expressed genes, even after dimorphism has become apparent. Overall design: 20 total sample: two time points, two sexes, and gonadal cells or whole animals. The earlier time point was collected in triplicate and was harvested 9.5 hours after starved, hatched L1s were fed. The later time point was collected in duplicate and was harvested 15 hour after starved, hatched L1 were fed. Replicates of either dissociated whole animals or gonadal cells (Z1/Z4 or Z1/Z4 daughter) from both male and hermaphrodites were harvested for each time point.
Cell-Specific mRNA Profiling of the Caenorhabditis elegans Somatic Gonadal Precursor Cells Identifies Suites of Sex-Biased and Gonad-Enriched Transcripts.
Sex, Specimen part, Subject, Time
View SamplesPost-hybridization washing is an essential part of microarray experiments. Both, the quality of the experimental washing protocol and the adequate consideration of washing in intensity calibration ultimately affect the quality of the expression estimates extracted from the microarray intensities. We conducted experiments on GeneChip microarrays with altered protocols for washing, scanning and staining to study the probe-level intensity changes as a function of washing cycles. Particularly, three Affymetrix GeneChip HGU133plus2 arrays were hybridized and equilibrated for 16 hours in the hybridization oven. For one of the three arrays washing and staining was performed according to the manufacturers instructions. For another array the first scan was done immediately after low stringent wash and staining without intermitting stringent washing. Then, the array was stringently washed and scanned in alternating order three more times where each washing step consists of a definite number of washing cycles. The third array was low stringently washed followed by two stringent washing cycles and staining before the first scan. Subsequently it was analogously processed as array A. All three chips are repeatedly processed in a second series of alternating wash/scan-cycles which was performed using the same protocol for each chip as in the first series as described above. As in the first series the arrays were also stained a second time to compensate for any loss of bleached fluorescent dye. Analysis of the washing kinetics shows that the signal-to-noise ratio doubles roughly every ten stringent washing cycles. Washing can be characterized by time-dependent rate constants which reflect the heterogeneous character of target binding to microarray probes. We propose an empirical washing function which estimates the survival of probe bound targets. The washing function allows calibrating probe intensities for the effect of washing. On a relative scale, proper calibration for washing markedly increases expression measures especially in the limit of small and large values.
Washing scaling of GeneChip microarray expression.
Cell line
View SamplesGene expression analysis identified a MLL translocation-specific signature of differentially expressed genes discriminating ALL and AML with and without MLL rearrangements.
MLL rearrangements in pediatric acute lymphoblastic and myeloblastic leukemias: MLL specific and lineage specific signatures.
No sample metadata fields
View SamplesGeminin is a small nucleoprotein that neuralizes ectoderm in the Xenopus embryo. Geminin promotes neural fate acquisition of mouse embryonic stem cells: Geminin knockdown during neural fate acquisition decreased expression of neural precursor cell markers (Pax6, Sox1), while increasing expression of Pitx2, Lefty1 and Cited2, genes involved in formation of the mouse node. Here we differentiated mouse embryonic stem cells into embryoid bodies to study Geminin's ability to repress primitive streak mesendoderm fate acquisition. We used microarrays to define the sets of genes that are regulated by Geminin during cell fate acquisition in embryoid bodies, using Dox-inducible Geminin knockdown or overexpression mouse embryonic stem cell lines.
Geminin restrains mesendodermal fate acquisition of embryonic stem cells and is associated with antagonism of Wnt signaling and enhanced polycomb-mediated repression.
Specimen part
View SamplesGeminin cooperates with Polycomb to restrain multi-lineage commitment in the early embryo: Transient maintenance of a pluripotent embryonic cell population followed by the onset of multi-lineage commitment is a fundamental aspect of development. However, molecular regulation of this transition is not well characterized in vivo. Here we demonstrate that the nuclear protein Geminin is required to restrain commitment and spatially restrict mesoderm, endoderm, and non-neural ectoderm to their proper locations in the Xenopus embryo. We used microarray analyses to demonstrate that Geminin overexpression represses many genes associated with cell commitment and differentiation, while elevating expression levels of genes that maintain pluripotent early and immature neurectodermal cell states. We characterized Geminins relationship to cell signaling and found that Geminin broadly represses Activin-, FGF-, and BMP-mediated cell commitment. Conversely, Geminin knockdown enhances commitment responses to growth factor signaling and causes ectopic mesodermal, endodermal, and epidermal fate commitment in the embryo. We also characterized Geminins functional relationship with transcription factors that had similar activities and found that Geminin represses commitment independent of Oct4 ortholog (Oct25/60) activities, but depends upon intact Polycomb repressor function. Consistent with this, chromatin immunoprecipitation assays directed at mesodermal genes demonstrate that Geminin promotes Polycomb binding and Polycomb-mediated repressive histone modifications, while inhibiting modifications associated with gene activation. This work defines Geminin as an essential regulator of the embryonic transition from pluripotency through early multi-lineage commitment, and demonstrates that functional cooperativity between Geminin and Polycomb contributes to this process.
Geminin cooperates with Polycomb to restrain multi-lineage commitment in the early embryo.
No sample metadata fields
View SamplesNematode derived substances are known to down regulate host immune responses in order to survive in the human host. Brugia malayi is a parasitic nematode responsible for long lasting and disabling infection known as lymphatic filariasis in humans. The therapeutic benefit of a controlled parasitic nematode infection on the course of inflammatory bowel disease (IBD) has been demonstrated in both animal and human models. However the inability of individual purified nematode proteins to recreate this beneficial effect has limited the application of component immunotherapy to human disease. This experiment addresses the hypothesis that the genes regulated by IL8 and recombinant Brugia malayi AsnRS (rBmAsnRS) are different even though it is known that both molecules interact with IL-8 receptors. Furthermore, we theorize that the signal transduction pathways activated by IL-8 and rBmAsnRS are different because it is known that the extracellular G protein loops utilized by IL-8 and rBmAsnRS to activate IL8 receptors, are different. These results obtained with a single recombinant nematode protein, rBmAsnRS, share immunological features with those observed in a whole nematode infection and include desirable features for treatment of idiopathic inflammatory diseases, such as IBD.
Nematode asparaginyl-tRNA synthetase resolves intestinal inflammation in mice with T-cell transfer colitis.
Specimen part
View SamplesFormation of the complex vertebrate nervous system begins when pluripotent cells of the early embryo are directed to acquire a neural fate. Although cell intrinsic controls play an important role in this process, the molecular nature of this regulation is not well defined. Here we assessed the role for Geminin, a nuclear protein expressed in embryonic cells, in neural fate acquisition from mouse embryonic stem (ES) cells. While Geminin knockdown does not affect the ability of ES cells to maintain or exit pluripotency, we found that it significantly impairs their ability to acquire a neural fate. Conversely, Geminin overexpression promotes neural gene expression, even in the presence of growth factor signaling that antagonizes neural transcriptional responses. These data demonstrate that Geminins activity contributes to mammalian neural cell fate acquisition. We investigated the mechanistic basis of this phenomenon and found that Geminin maintains a hyperacetylated and open chromatin conformation at neural genes. Interestingly, recombinant Geminin protein also rapidly alters chromatin acetylation and accessibility even when Geminin is combined with nuclear extract and chromatin in vitro. These findings define a novel activity for Geminin in regulation of chromatin structure. Together, these data support a role for Geminin as a cell intrinsic regulator of neural fate acquisition that promotes expression of neural genes by regulating chromatin accessibility and histone acetylation.
Geminin promotes neural fate acquisition of embryonic stem cells by maintaining chromatin in an accessible and hyperacetylated state.
Specimen part, Treatment
View SamplesThis work uses a time series in order to decipher gene relationships and consequently to build core regulatory networks involved in Arabidopsis root adaptation to NO3- provision. The experimental approach has been to monitor genome response to NO3- at 3, 6, 9, 12, 15 and 20 min, using ATH1 chips. This high-resolution time course analysis demonstrated that the previously known primary nitrate response is actually preceded by very fast (within 3 min) gene expression modulation, involving genes/functions needed to prepare plants to use/reduce NO3-. State-space modeling (a machine learning approach) has been used to successfully predict gene behavior in unlearnt conditions.
Predictive network modeling of the high-resolution dynamic plant transcriptome in response to nitrate.
Specimen part, Treatment
View Samples