Regulation of the cell cycle is intimately linked to erythroid differentiation, yet how these processes are coupled is not well understood. To gain insight into this coordinate regulation, we examined the role that the retinoblastoma protein (Rb), a central regulator of the cell cycle, plays in erythropoiesis. We found that Rb serves a cell-intrinsic role and its absence causes ineffective erythropoiesis, with a differentiation block at the transition from early to late erythroblasts. Unexpectedly, in addition to a failure to properly exit the cell cycle, mitochondrial biogenesis fails to be upregulated concomitantly, contributing to this differentiation block. The link between erythropoiesis and mitochondrial function was validated by inhibition of mitochondrial biogenesis. Erythropoiesis in the absence of Rb resembles the human myelodysplastic syndromes, where defects in cell cycle regulation and mitochondrial function frequently occur. Our work demonstrates how these seemingly disparate pathways play a role in coordinately regulating cellular differentiation.
Rb intrinsically promotes erythropoiesis by coupling cell cycle exit with mitochondrial biogenesis.
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View SamplesLymph node vs. tonsil
Differential expression of a gene signature for scavenger/lectin receptors by endothelial cells and macrophages in human lymph node sinuses, the primary sites of regional metastasis.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Dissecting the retinoid-induced differentiation of F9 embryonal stem cells by integrative genomics.
Cell line, Time
View SamplesRetinoic acid (RA) triggers physiological processes by activating heterodimeric transcription factors comprising retinoic acid (RARa,b,g) and retinoid X (RXRa,b,g) receptors. How a single signal induces highly complex temporally controlled networks that ultimately orchestrate physiological processes is unclear. Using an RA-inducible differentiation model we defined the temporal changes in the genome-wide binding patterns of RARg and RXRa and correlated them with transcription regulation. Unexpectedly, both receptors displayed a highly dynamic binding, with different RXRa heterodimers targeting identical loci. Comparison of RARg and RXRa co-binding at RA-regulated genes identified putative RXRa-RARg target genes that were validated with subtype-selective agonists. Gene regulatory decisions during differentiation were inferred from transcription factor target gene information and temporal gene expression. This analysis revealed 6 distinct co-expression paths of which RXRa-RARg is associated with transcription activation, while Sox2 and Egr1 were predicted to regulate repression. Finally, RXRa-RARg regulatory networks were reconstructed through integration of functional co-citations. Our analysis provides a dynamic view of RA signalling during cell differentiation, reveals RA heterodimer dynamics and promiscuity, and predicts decisions that diversify the RA signal into distinct gene-regulatory programs.
Dissecting the retinoid-induced differentiation of F9 embryonal stem cells by integrative genomics.
Cell line, Time
View SamplesThe importance of regulatory T cells (Treg) for immune tolerance is well recognized, yet the signaling molecules influencing their suppressive activity are relatively poorly understood. We identified the cytoplasmic tyrosine phosphatase SHP-1 as a novel endogenous brake and modifier of the suppressive ability of Treg cells; consistent with this notion, loss of SHP-1 expression strongly augments the ability of Treg cells to suppress inflammation in a mouse model. Specific harmacological inhibition of SHP-1 enzymatic activity via the cancer drug sodium stibogluconate (SSG) potently augmented Treg cell suppressor activity both in vivo and ex vivo.
The protein tyrosine phosphatase SHP-1 modulates the suppressive activity of regulatory T cells.
Specimen part
View SamplesSalmonella enterica serotype Typhimurium cause a localized enteric infection in immunocompetent patients while human immunodeficiency virus (HIV)-infected patients develop a life threatening bacteremia. We used a rhesus macaque ileal loop model to study how simian immunodeficiency virus (SIV) infection triggers defects in mucosal barrier function that enhance S. Typhimurium dissemination. SIV infection resulted in significant depletion of CD4+ T cells in the intestinal mucosa. Gene expression profiling revealed a defective TH17 response (with suppression of IL-17 and IL-22 expression) and impaired homeostasis of the intestinal epithelium in SIV-infected animals during NTS infection. These findings correlated with an impaired ability of lamina propria CD4+ T cells from SIV-infected macaques to produce IL-17 upon ex vivo stimulation, while production of IFN-gamma was not affected. This cytokine imbalance in SIV-infected animals was associated with reduced expression of genes required for intestinal epithelial maintenance and repair, increased fluid secretion during NTS infection, epithelial damage and translocation of a non-invasive S. Typhimurium mutant. Although no defects in neutrophil recruitment were noted, the ileum of SIV-infected animals contained lower levels of the enzyme myeloperoxidase, which may indicate defects in neutrophil killing capacity. S. Typhimurium was recovered in markedly increased numbers from the mesenteric lymph nodes of SIV-infected macaques, illustrating the increased potential for systemic dissemination during co-infection. Our data suggest that SIV-infection causes a multi-factorial defect in mucosal barrier function that promotes bacterial dissemination.
Simian immunodeficiency virus-induced mucosal interleukin-17 deficiency promotes Salmonella dissemination from the gut.
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View SamplesMesenchymal stem cells (MSCs) and their cellular response to various stimuli have been characterized in great detail in culture conditions. In contrast, the cellular response of MSCs in an in vivo setting is still uncharted territory. In this study, we investigated the cellular response of MSCs following transplantation into spinal cord injury (SCI).Mouse bone marrow-derived MSCs were transplanted 24h following severe contusion SCI in mice. As controls, MSCs transplanted to uninjured spinal cord and non-transplanted MSCs were used. At seven days post transplantation, the MSCs were isolated from the SCI, and their global transcriptional changes investigated using RNA-sequencing. We found that MSCs transplanted into SCI down-regulate their response to cytokines, tendency to adhere and to undergo phagocytosis but up-regulate their ability to repair DNA and proliferate. Overall design: Evaluation of transcriptional changes in transplanted mesenchymal stem cells.
Mesenchymal stem cells transplanted into spinal cord injury adopt immune cell-like characteristics.
Subject
View SamplesImmunodeficient mouse models have been valuable for studies of human hematopoiesis, but high-fidelity recapitulation of erythropoiesis in most xenograft recipients remains elusive. Recently developed immunodeficient and Kit mutant mice, however, have provided a suitable background to achieve higher-level human erythropoiesis after long-term hematopoietic engraftment. While there has been some characterization of human erythropoiesis in these models, a comprehensive analysis of various developmental stages has not yet been reported. Here, we have utilized cell surface phenotypes, morphologic analyses, and molecular studies to fully characterize human erythropoiesis from multiple developmental stages in immunodeficient and Kit mutant mouse models following long-term hematopoietic stem and progenitor cell engraftment. We show that human erythropoiesis in such models demonstrates complete maturation and enucleation, as well as developmentally appropriate globin gene expression. These results provide a framework for future studies to utilize this model system for interrogating disorders affecting human erythropoiesis and for developing improved therapeutic approaches. Overall design: (mRNA-seq) RNA-seq of human CD235a+ cells isolated 14-16 weeks post-implantation from mouse bone marrow were performed for three biological replicates each of mice xenograted with adult bone marrow-derived human CD34+ cells and cord blood-derived CD34+ cells.
Developmentally-faithful and effective human erythropoiesis in immunodeficient and Kit mutant mice.
Specimen part, Subject
View SamplesWe used microarrays to detail the global gene expression changes in the ileum of SIV-infected and uninfected macaques following administration of L. plantarum.
PPARα-targeted mitochondrial bioenergetics mediate repair of intestinal barriers at the host-microbe intersection during SIV infection.
Specimen part, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
RKIP and HMGA2 regulate breast tumor survival and metastasis through lysyl oxidase and syndecan-2.
Specimen part, Cell line
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