Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression profile of Dicer knockout in mouse DP thymocytes

ABSTRACT: The RNase III enzyme dicer is essential for the processing of microRNAs (miRNAs) and small interfering RNAs (siRNAs) from double-stranded RNA precursors. miRNAs and siRNAs regulate chromatin structure, gene transcription, mRNA stability and translation in a wide range of organisms. To provide a model system to explore the role of dicer-generated RNAs in the differentiation of mammalian cells in vivo, we have generated a conditional dicer allele. Deletion of dicer at an early stage of T cell development compromised the survival of αβ lineage cells, while the numbers of γδ-expressing thymocytes were not affected. In developing thymocytes, dicer was not required for the maintenance of transcriptional silencing at pericentromeric satellite sequences (constitutive heterochromatin), the maintenance of cytosine DNA methylation and X chromosome inactivation in female cells (facultative heterochromatin) and the stable shutdown of a developmentally regulated gene (developmentally regulated gene silencing). Most remarkably, given that one-third of mammalian mRNAs are putative miRNA targets, dicer appears to be dispensable for CD4/8 lineage commitment, a process where epigenetic regulation of lineage choice has been well documented. Thus, although dicer appears critical for the development of the early embryo, it may have limited impact on the implementation of lineage-specific gene expression programs. LckCre was used to delete a floxed Dicer1 allele from developing thymocytes (Cobb BS, Nesterova TB, Thompson E, Hertweck A, O'Connor E, Godwin J, Wilson CB, Brockdorff N, Fisher AG, Smale ST and Merkenschlager M. T cell lineage choice and differentiation in the absence of the RNAse III enzyme dicer. J. Exp. Med. 2005 201: 1367-1373). Thymocytes were stained for CD4 and CD8, and double-positive (DP) thymocytes were sorted by flow cytometry. Three biological replicates of Dicer lox/lox control samples and LckCre Dicer lox/lox KO samples were analysed.

ORGANISM(S): Mus musculus

SUBMITTER: Gopuraja Dharmalingam

PROVIDER: E-GEOD-57511 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:CD5 is characterized as an inhibitory co-receptor with important regulatory role during T cell development. To study the molecular mechanism by which CD5 operates, we used quantitative mass spectrometry to analyze the components of the CD5 signaling machinery in primary T cells. In a first set of experiments, CD5-containing complexes were immunoprecipitated from thymocytes of wild-type (WT) C57BL/6 mice. Thymocytes were treated with pervanadate to induce widespread activation of protein tyrosine kinases. Corresponding samples prepared from thymocytes of Cd5−/− mice were used as controls, to discriminate CD5-binding molecules from the background of contaminant proteins. Eight biological replicates were prepared for both conditions, and samples were analyzed in duplicate LC-MS runs. This first set of experiment is presented in TableS1 of the paper, and is associated to the MaxQuant result file “Interactome WT” in the present PX dataset. We analyzed the CD5 interactome at different time of stimulation with pervanadate (1min and 10min) using thymocytes from wild-type (WT) C57BL/6 mice. Corresponding samples prepared from thymocytes of Cd5−/− mice were used as controls. Three biological replicates were prepared for both conditions (WT and KO) and each time point (1min and 10min). This set of experiments is presented in TableS2 of the paper and is associated to the MaxQuant result file “Interactome at 1min and 10min” in the present PX dataset. We checked that the activation of CD5 (phosphorylation sites) and the formation of the signaling complex was comparable in different stimulatory conditions (comparison of WT thymocytes stimulated with either pervanadate or anti-CD3+anti-CD4 antibodies). We also analyzed the binding of CD5 interactors in thymocytes from a c-Cbl-/- mouse model (comparison of WT and c-Cbl-/-thymocytes stimulated with pervanadate). These experiments and the associated experimental design of the comparisons are summarized in TableS3 of the paper, and are based on the MaxQuant result file “Comparison of different stimulatory conditions” in this dataset. To check the phosphorylation status of the CD5 tyrosine residues at different time of stimulation, we analyzed samples immunoprecipitated from thymocytes of wild-type (WT) C57BL/6 mice, following stimulation with anti-CD3+anti-CD4 antibodies for 1min, 3min and 10min. This set of experiment is presented in TableS4 of the paper and is associated to the MaxQuant result file “CD5 pY kinetics” in the present PX dataset. To determine the role of Y429 in the context of CD5 signaling, we expressed a wild-type (CD5tgWt) or a mutated form of CD5, containing a tyrosine to phenylalanine substitution at position 429 (CD5tgY429F) in transgenic mice. We analyzed the CD5 interactome by comparing samples immunoprecipitated from thymocytes of these 2 mice models (following pervanadate stimulation, 6 and 5 biological replicates respectively) with samples prepared in the same way from Cd5−/− mice as controls (6 biological replicates). The results are shown in TableS5 of the paper, and correspond to the MaxQuant result file “interactome CD5tgWt_CD5tgY429F”.

Project description:Glucocorticoids play a role in regulation of T lymphocytes homeostasis and development. In particular, glucocorticoid treatment induces massive apoptosis of CD4+CD8+ double positive (DP) thymocytes. This effect is due to many mechanisms, mainly driven by modulation of gene transcription. To find out which genes are modulated, we analyzed DP thymocytes treated for 3 hours with dexamethasone or medium alone, by global gene expression profiling using the Affymetrix technology (MGU74Av2 GeneChip). The data were analyzed with MAS 5.0 imposing a cut off of 1.7 fold in up regulation and 1.35 fold in down regulation. To further filter results we also used the statistical software, SAM (d 0.88 see figure 1s in supplementary data of the above cited manuscript). Results indicate modulation of 156 genes, also confirmed by either RNAse protection assay or Real Time PCR. For data mining we also used Go Miner to explore the Gene Ontology data bank (see tables 1-3 of the above cited manuscript). The overall results demonstrated that dexamethasone caused the down-regulation of genes promoting survival of DP thymocytes (e.g. Notch1, Socs1 and Id3) or the modulation of genes activating cell death through the ceramide pathway (Ugcg, Sgpp1, Degs1 and Gpr65) or through the mithocondrial machinery. Among the latter, there are Bcl-2 family members (Bim, Bfl-1, Bcl-xL and Bcl-xbeta), genes involved in the control of redox status (thioredoxin reductase, TXNIP and idh2) and genes belonging to Tis11 family which are involved in mRNA stability. Our study suggests that dexamethasone treatment of DP thymocytes modulates several genes belonging to apoptosis-related systems that can contribute to their apoptosis. Experiment Overall Design: Thymi from 4 week old C3H/HeN mice were teased in culture medium, CD4+CD8+ double positive (DP) thymocytes were sorted with microbeads Miltenyi Biotech methods and were plated in 6 well plates with 3 ml of the culture medium at a concentration of 5.0E+06 cell/ml together with 1E-07 M Dexamethasone or a corresponding volume of PBS. DP thymocytes were kept at 37Â°C, 5% CO2 in a humidified atmosphere for 3 hours. Total RNA was extracted and analyzed. We used 2 technical replicate-extracts.

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Gene expression profile of Dicer knockout in mouse DP thymocytes

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