The hematopoietic microenvironment consists of non-hematopoietic derived stromal elements and hematopoietic derived monocytes and macrophages which interact and function together to control the proliferation and differentiation of early blood-forming cells. Two human stromal cell lines (HS-5 and HS-27a) representing distinct functional components of this microenvironment have been extensively characterized and shown to influence monocyte gene expression. This series of gene expression profiles is intended to extend the previous studies and identify which gene expression changes may require cell-cell contact or occur in the stromal cells as a result of monocyte influence;or in the monocytes as a result of stormal influences.
Functionally and phenotypically distinct subpopulations of marrow stromal cells are fibroblast in origin and induce different fates in peripheral blood monocytes.
Sex
View SamplesThe bone marrow microenvironment is a complex mixture of cells that function in concert to regulate hematopoiesis. Cellular components include fixed nonhematopoietic stromal elements as well as monocytes and resident macrophages, which are derived from the hematopoietic stem cells. Although these monocyte-lineage cells are reported to modify stromal cell function, the reverse also occurs. Given the secretory capability of the monocyte/macrophage and their various potential functions, it is not surprising that stromal cells contained within a particular niche can modify monocyte gene expression and functional maturation.
Functionally and phenotypically distinct subpopulations of marrow stromal cells are fibroblast in origin and induce different fates in peripheral blood monocytes.
Sex
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Inflammation-induced repression of chromatin bound by the transcription factor Foxp3 in regulatory T cells.
Specimen part
View SamplesThe transcription factor Foxp3 is indispensable for the ability of regulatory T (Treg) cells to suppress fatal inflammation. Here, we characterized the role of Foxp3 in chromatin remodeling and regulation of gene expression in actively suppressing Treg cells in an inflammatory setting. Although genome-wide Foxp3 occupancy of DNA regulatory elements was similar in resting and in vivo activated Treg cells, Foxp3-bound enhancers were poised for repression only in activated Treg cells. Following activation, Foxp3-bound sites showed reduced chromatin accessibility and selective H3K27 tri-methylation, which was associated with Ezh2 recruitment and downregulation of nearby gene expression. Thus, Foxp3 poises its targets for repression by facilitating formation of repressive chromatin in regulatory T cells upon their activation in response to inflammatory cues.
Inflammation-induced repression of chromatin bound by the transcription factor Foxp3 in regulatory T cells.
Specimen part
View SamplesBackground: Developmental stage-specific globin expression is a complex phenomenon that involves both trans- and cis-acting elements. While functional analyses ensuing recent genome-wide association studies have highlighted the important roles of trans-factors in regulating hemoglobin expression, these factors can not exert their functions without permissive chromatin domains. By transferring thoroughly profiled beta globin locus of undifferentiated human embryonic stem cells (hESCs) or hESC-derived erythroid cells into an adult erythroid transcriptional environment, we studied the influences of histone modifications on the globin expression decision within a fixed transcriptional environment. Shortly after the locus transfer, embryonic epsilon globin was not expressed regardless of original chromatin states, whereas fetal gamma globin was either expressed or not activated depending on original chromatin configurations, and the originally silent adult beta globin either remained silent or became activated depending on the expression status of gamma globin. These data suggest the interplay between transcriptional environment and the chromatin modifications determine the outcome of globin expression. As the ultimate silencing of gamma globin from hESC-derived erythroid cells in the adult transcriptional environment occurred after months-long cell proliferation, our work also has implications on attempts to generate beta globin expressing erythroid cells from hESCs or induced pluripotent stem cells.
Transcriptional environment and chromatin architecture interplay dictates globin expression patterns of heterospecific hybrids derived from undifferentiated human embryonic stem cells or from their erythroid progeny.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Combinatorial assembly of developmental stage-specific enhancers controls gene expression programs during human erythropoiesis.
Specimen part
View SamplesTo facilitate comparative genomic analyses of human fetal and adult cells undergoing erythropoiesis, we employed a serum-free two-phase liquid culture system to expand and differentiate primary human CD34+ hematopoietic stem/progenitor cells (HSPCs) ex vivo. In this experimental context, highly enriched populations of stage-matched, differentiating, primary proerythroblasts (ProEs) were generated. We selected four time points (day 0, CD34+ HSPCs; day 3, 5, and 7, differentiating ProEs) that represented similar stages differentiation for gene expression profiling using microarrays.
Combinatorial assembly of developmental stage-specific enhancers controls gene expression programs during human erythropoiesis.
Specimen part
View SamplesIRF2, IRF6, and MYB are candidate regulators of human erythropoiesis. We here examine primary CD34+ hematopoietic stem/progenitor cells (HSPCs)-derived erythroid progenitors with control, IRF2, IRF6, or MYB shRNA lentiviral transduction prior to differentiation. Gene expression microarray profiling datasets for MYB shRNA and control shRNA were obtained from Gene Expression Omnibus (GEO) under accession number GSE25678. The data were analyzed together with the datasets obtained in this study.
Combinatorial assembly of developmental stage-specific enhancers controls gene expression programs during human erythropoiesis.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Foxp3 exploits a pre-existent enhancer landscape for regulatory T cell lineage specification.
Specimen part
View SamplesRegulatory T (Treg) cells, whose identity and function are defined by the transcription factor Foxp3, are indispensable for immune homeostasis. It is unclear whether Foxp3 exerts its Treg lineage specification function through active modification of the chromatin landscape and establishment of new enhancers or by exploiting a pre-existing enhancer landscape. Analysis of the chromatin accessibility of Foxp3-bound enhancers in Treg and Foxp3-negative T cells showed that Foxp3 was bound overwhelmingly to pre-accessible enhancers occupied by its cofactors in precursor cells or a structurally related predecessor. Furthermore, the bulk of Foxp3-bound Treg cell enhancers inaccessible in Foxp3- CD4+ cells became accessible upon T cell receptor activation prior to Foxp3 expression with only a small subset associated with several functionally important genes being exclusively Treg cell-specific. Thus, in a late cellular differentiation process Foxp3 defines Treg cell functionality in an opportunistic manner by largely exploiting the preformed enhancer network instead of establishing a new enhancer landscape.
Foxp3 exploits a pre-existent enhancer landscape for regulatory T cell lineage specification.
Specimen part
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