Overexpression of Gfi1b in a pro-B Abelson murine leukemia virus transformed cell line
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ABSTRACT: We have conducted a screen for factors that downregulate expression of the genes encoding the V(D)J recombinase (RAG1 and RAG2) during B cell development. We have identified the transcription factor Gfi1B as being one of the proteins capable of decreasing RAG transcription when overexpressed in Ableson transormed ProB cell lines. We have yet to determine whether the overexpression of Gfi1B downregulates the RAGs directly, or whether it initiates a signalling programme that results in RAG downregulation. We hypothesize that by comparing global gene expression patterns in cells that overexpress Gfi1B and those that do not, we can distinguish between these possibilities and additionally gain insight into the broader genetic program that may be influenced by Gfi1B during hematopoiesis. Abelson pro-B cells were infected with a retrovirus encoding Gfi1b fused to the estrogen receptor domain. Gfi1b expression was induced by adding tamoxifen to the culture medium for 12h. Three biological replicates of untreated and treated cells were analyzed.
Project description:We have conducted a screen for factors that downregulate expression of the genes encoding the V(D)J recombinase (RAG1 and RAG2) during B cell development. We have identified the transcription factor Gfi1B as being one of the proteins capable of decreasing RAG transcription when overexpressed in Ableson transormed ProB cell lines. We have yet to determine whether the overexpression of Gfi1B downregulates the RAGs directly, or whether it initiates a signalling programme that results in RAG downregulation. We hypothesize that by comparing global gene expression patterns in cells that overexpress Gfi1B and those that do not, we can distinguish between these possibilities and additionally gain insight into the broader genetic program that may be influenced by Gfi1B during hematopoiesis.
Project description:Growth factor independence genes (Gfi1 and Gfi1b) repress recombination activating genes (Rag) transcription in developing B lymphocytes. Because all blood lineages originate from hematopoietic stem cells (HSCs) and different lineage progenitors have been shown to share transcription factor networks prior to cell fate commitment, we hypothesized that GFI family proteins may also play a role in repressing Rag transcription or a global lymphoid transcriptional program in other blood lineages. We tested the level of Rag transcription in various blood cells when Gfi1 and Gfi1b were deleted, and observed an upregulation of Rag expression in plasmacytoid dendritic cells (pDCs). Using microarray analysis, we observed that Gfi1 and Gfi1b regulate a broad spectrum of cellular processes in pDCs, but not a lymphoid specific transcriptional program. This study establishes a role for Gfi1 and Gfi1b in Rag regulation in a non-B lineage cell type
Project description:Growth factor independence genes (Gfi1 and Gfi1b) repress recombination activating genes (Rag) transcription in developing B lymphocytes. Because all blood lineages originate from hematopoietic stem cells (HSCs) and different lineage progenitors have been shown to share transcription factor networks prior to cell fate commitment, we hypothesized that GFI family proteins may also play a role in repressing Rag transcription or a global lymphoid transcriptional program in other blood lineages. We tested the level of Rag transcription in various blood cells when Gfi1 and Gfi1b were deleted, and observed an upregulation of Rag expression in plasmacytoid dendritic cells (pDCs). Using microarray analysis, we observed that Gfi1 and Gfi1b regulate a broad spectrum of cellular processes in pDCs, but not a lymphoid specific transcriptional program. This study establishes a role for Gfi1 and Gfi1b in Rag regulation in a non-B lineage cell type Gfi1f/f; Gfi1bf/f; ERCre bone marrow progenitors were untreated and treated with tamoxifen (4OHT) to delete floxed alleles during pDC differentiation in culture. Cells from three individual mouse constitute triplicates of untreated (-4OHT) and treated (+4OHT) conditions, corresponding to wildtype or knockout genotypes.
Project description:The RAG1 endonuclease, together with its cofactor RAG2, is essential for V(D)J recombination but is a potent threat to genome stability. The sources of RAG1 mistargeting and the mechanisms that have evolved to suppress it are poorly understood. Here, we report the surprising finding that RAG1 binds to thousands of sites in the genome of developing lymphocytes, primarily at active promoters and enhancers. The genome has responded by reducing the abundance of "cryptic" recombination signals near sites of RAG1 binding. This depletion operates specifically on the RSS heptamer, with nonamers enriched at RAG1 binding sites. Reversing this RAG-driven depletion of cleavage sites by insertion of strong recombination signals creates an ectopic hub of RAG-mediated V(D)J recombination and chromosomal translocations. Our findings delineate rules governing RAG binding in the genome, identify areas at risk of RAG-mediated damage, and highlight the evolutionary struggle to accommodate programmed DNA damage in developing lymphocytes. RAG1,RAG2 and H3K4me3 ChIP-seq profiles of human thymocytes, mouse thymocytes and preB cells, and Abelson pre-B cell line treated with STI-571
Project description:Transcriptome analysis of mouse embryonic stem cell lines derived from embryos cultured in optimal and suboptimal conditions compared to cell lines derived from control embryos. The use of assisted reproductive technologies (ART) such as in vitro fertilization (IVF) has resulted in the birth of more than 5 million children. While children conceived by these technologies are generally healthy, there is conflicting evidence suggesting an increase in adult-onset complications like glucose intolerance and high blood pressure in IVF children. Animal models indicate similar potential risks. It remains unclear what molecular mechanisms may be operating during in vitro culture to predispose the embryo to these diseases. One of the limitations faced by investigators is the paucity of the material in the preimplantation embryo to test for molecular analysis. To address this problem, we generated mouse embryonic stem cells (mESC) from blastocysts conceived after natural mating (mESCFB) or after IVF, using optimal (KSOM + 5% O2; mESCKAA) and suboptimal (Whitten’s Medium, + 20% O2, mESCWM) conditions. We analyzed three female cell lines per group for a total of nine mouse embryonic stem cells on Affymetrix MoGene 1.0 ST Arrays.
Project description:Primordial germ cells (PGCs), the embryonic precursors of eggs and sperm, are a unique model for identifying and studying regulatory mechanisms in singly migrating cells. From their time of specification to eventual colonization of the gonad, mouse PGCs traverse through and interact with many different cell types, including epithelial cells and mesenchymal tissues. Work in drosophila and zebrafish have identified many genes and signaling pathways involved in PGC migration, but little is known about this process in mammals. We have generated a point mutation in the Ror2 gene that we know disrupts primordial germ cell migration in the developing mouse embryo. We used microarray analysis to determine if this defect is mediated through genome-wide or pathway-specific transcriptional changes. We analyzed primordial germ cells (PGCs) from 4 wild-type (WT) and 4 Ror2Y324C/Y324C mutant embryos using Oct4-DPE-EGFP. PGCs were collected during their active migratory state at embryonic day 9.5 (somite range 20-25).
Project description:We used microarrays to compare gene expression between three HRAS-wild type lines (13, 162d, 165d) and three HRAS-G12S mutant lines (7, 8, 16). Arrays were conducted in all lines from iPSC-derived astroglial progenitors at 8 weeks of differentiation, and in wild-type astrocyte lines at 28 weeks of differentiation. Cells of the astroglial lineage were generated for RNA extraction and hybridization on Affymetrix Human 1.0 ST microarrays. At each stage, cells were plated as a monolayer and treated with 10ng/ml of CNTF for one week before extraction.
Project description:ATAC-seq of pre-proB, proB and preB populations from Ergfl/fl bone marrow, pre-proB cell population from Rag1CreT/+;ErgΔ/Δ bone marrow, and pre-proB, proB and preB populations from from Rag1CreT/+;ErgΔ/Δ;IgHVH10tar bone marrow.
Project description:Astrocytes, the most abundant cells in the central nervous system, promote synapse formation and help refine neural connectivity. Although they are allocated to spatially distinct regional domains during development, it is unknown whether region-restricted astrocytes are functionally heterogeneous. Here we show that postnatal spinal cord astrocytes express several region-specific genes, and that ventral astrocyte-encoded Semaphorin3a (Sema3a) is required for proper motor neuron and sensory neuron circuit organization. Loss of astrocyte-encoded Sema3a led to dysregulated α−motor neuron axon initial segment orientation, markedly abnormal synaptic inputs, and selective death of α−but not of adjacent γ−motor neurons. Additionally, a subset of TrkA+ sensory afferents projected to ectopic ventral positions. These findings demonstrate that stable maintenance of a positional cue by developing astrocytes influences multiple aspects of sensorimotor circuit formation. More generally, they suggest that regional astrocyte heterogeneity may help to coordinate postnatal neural circuit refinement. 12 total samples consisting of three biological replicates each of flow sorted postnatal day 7 dorsal spinal cord astrocytes, ventral spinal cord astrocytes, dorsal SC non astrocytes, and ventral SC non astrocytes