This SuperSeries is composed of the SubSeries listed below.
Genomics of TGF-beta1 signaling in stem cell commitment and dendritic cell development.
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View SamplesPolycomb group (PcG) proteins comprise a large group of evolutionary conserved factors with essential roles for embryonic development and adult stem cell function. PcG proteins constitute two main multiprotein polycomb repressive complexes (PRC1 and PRC2) that operate in a hierarchical manner to silence gene expression. Functionally distinct PRC1 complexes are defined by Polycomb group RING finger protein (PCGF) paralogs. So far, six PCGF paralogs (PCGF1-6) have been identified but paralog-specific functions are not well understood. In our studies, we observed that Pcgf6 showed the highest expression level in undifferentiated murine embryonic stem cells (ESCs), blastocysts and testes. When ESCs differentiated, Pcgf6 expression strongly declined. To further investigate Pcgf6 biology, we established dox-inducible shRNA knockdown (KD) ESCs. Following Pcgf6 KD in ESCs the expression of pluripotency genes decreased, while mesodermal- and spermatogenesis-specific genes were de-repressed. Concomitantly with the elevated expression of mesodermal lineage markers, Pcgf6 KD ESCs showed increased hemangioblastic and hematopoietic activities. Finally, PCGF6 replaced SOX2 but not KLF4 or c-MYC in the generation of germline-competent iPS cells. Forced expression of Pcgf6 in OSKM-driven reprogramming increases iPS efficiency while Pcgf6 KD reduces the formation of ESC-like colonies. Together, these analyses show that Pcgf6 is non-redundantly involved in maintaining the pluripotent nature of ESCs and functions in iPS reprogramming.
Pcgf6, a polycomb group protein, regulates mesodermal lineage differentiation in murine ESCs and functions in iPS reprogramming.
Specimen part, Cell line, Treatment
View SamplesEed (embryonic ectoderm development) is a core component of the Polycomb Repressive Complex 2 (PRC2) which catalyzes the methylation of histone H3 lysine 27 (H3K27). Trimethylated H3K27 (H3K27me3) can act as a signal for PRC1 recruitment in the process of gene silencing and chromatin condensation. Previous studies with Eed KO ESCs revealed a failure to down-regulate a limited list of pluripotency factors in differentiating ESCs. Our aim was to analyze the consequences of Eed KO for ESC differentiation. To this end we first analyzed ESC differentiation in the absence of Eed and employed in silico data to assess pluripotency gene expression and H3K27me3 patterns. We linked these data to expression analyses of wildtype and Eed KO ESCs. We observed that in wildtype ESCs a subset of pluripotency genes including Oct4, Nanog, Sox2 and Oct4 target genes progressively gain H3K27me3 during differentiation. These genes remain expressed in differentiating Eed KO ESCs. This suggests that the deregulation of a limited set of pluripotency factors impedes ESC differentiation. Global analyses of H3K27me3 and Oct4 ChIP-seq data indicate that in ESCs the binding of Oct4 to promoter regions is not a general predictor for PRC2-mediated silencing during differentiation. However, motif analyses suggest a binding of Oct4 together with Sox2 and Nanog at promoters of genes that are PRC2-dependently silenced during differentiation. In summary, our data further characterize Eed function in ESCs by showing that Eed/PRC2 is essential for the onset of ESC differentiation.
Polycomb protein EED is required for silencing of pluripotency genes upon ESC differentiation.
Specimen part, Cell line
View SamplesDendritic cells (DCs) in lymphoid tissue comprise conventional DCs (cDCs) and plasmacytoid DCs (pDCs) that develop from common DC progenitors (CDPs). CDPs are Flt3+c-kitintM-CSFR+ and reside in bone marrow. Here we describe a two-step culture system that recapitulates DC development from c-kithiFlt3-/lo multipotent progenitors (MPPs) into CDPs and further into cDC and pDC subsets. MPPs and CDPs are amplified in vitro with Flt3 ligand, stem cell factor, hyper-IL-6 and insulin- like growth factor-1. The four-factor cocktail readily induces self-renewal of MPPs and their progression into CDPs and has no self-renewal activity on CDPs. The amplified CDPs respond to all known DC poietins and generate all lymphoid tissue DCs in vivo and in vitro. Additionally, in vitro CDPs recapitulate the cell surface marker and gene expression profile of in vivo CDPs and possess a DC-primed transcription profile. Transforming growth factor-1 (TGF-1) impacts on CDPs and directs their differentiation towards cDCs. Genome-wide gene expression profiling of TGF-1-induced genes identified transcription factors, such as interferon regulatory factor-4 (IRF-4) and RelB, that are implicated as instructive factors for cDC subset specification. TGF-1 also induced the transcription factor inhibitor of differentiation/DNA binding 2 (Id2) that suppresses pDC development. Thus, TGF-1 directs CDP differentiation into cDC by inducing both cDC instructive factors and pDC inhibitory factors.
TGF-beta1 accelerates dendritic cell differentiation from common dendritic cell progenitors and directs subset specification toward conventional dendritic cells.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Hematopoietic stem and progenitor cells acquire distinct DNA-hypermethylation during in vitro culture.
Specimen part, Subject
View SamplesHematopoietic stem and progenitor cells (HPCs) can be maintained in vitro, but the vast majority of their progeny loses stemness during culture. We have analyzed DNA methylation (DNAm) profiles of freshly isolated CD34+ cells and upon expansion on either tissue culture plastic (TCP) or mesenchymal stromal cells (MSCs). Cultured HPCs acquired significant DNA-hypermethylation, particularly in up-stream promoter regions and shore-regions of CpG islands (CGIs). To analyze if these DNAm changes are relevant for differential gene expression we analyzed gene expression profiles of additional samples. As expected highly expressed genes (10% with highest signal intensity in gene expression arrays) were hardly methylated at promoter regions, CGIs and shore-regions.
Hematopoietic stem and progenitor cells acquire distinct DNA-hypermethylation during in vitro culture.
Specimen part, Subject
View SamplesComplete identification of the bone marrow niche remains one of the most progressing fields. Attempts to identify soluble factors involved in stem cell renewal have been less successful. We have previously shown that endothelial cells (EC) can induce the long-term proliferation of hematopoietic progenitor cells (HPC), especially when they had been subjected to an inflammatory stimulus like interleukins (IL) 1.
Interleukin 32 promotes hematopoietic progenitor expansion and attenuates bone marrow cytotoxicity.
Specimen part, Treatment, Time
View SamplesCord blood hematopoietic stem cells (CB-HSCs) are an outstanding source for transplantation approaches. However, the amount of cells per donor is limited and culture expansion of CB-HSCs is accompanied by a loss of engraftment potential. In order to analyze the molecular mechanisms leading to this impaired potential we profiled global and local epigenotypes during the expansion of human CB hematopoietic stem and progenitor cells (HPSCs). Human CB-derived CD34+ cells were cultured in serum-free medium together with SCF, TPO, FGF, with or without Igfbp2 and Angptl5 (STF/STFIA cocktails). As compared to the STF cocktail, the STFIA cocktail maintains in vivo repopulation capacity of cultured CD34+ cells. Upon expansion, CD34+ cells genome-wide remodel their epigenotype and depending on the cytokine cocktail, cells show different H3K4me3 and H3K27me3 levels. Expanding cells without Igfbp2 and Angptl5 leads to higher global H3K27me3 levels. ChIPseq analyses reveal a cytokine cocktail-dependent redistribution of H3K27me3 profiles. Inhibition of the PRC2 component EZH2 counteracts the culture-associated loss of NOD scid gamma (NSG) engraftment potential. Collectively, our data reveal chromatin dynamics that underlie the culture-associated loss of engraftment potential. We identify PRC2 component EZH2 as being involved in the loss of engraftment potential during the in vitro expansion of HPSCs.
PRC2 inhibition counteracts the culture-associated loss of engraftment potential of human cord blood-derived hematopoietic stem and progenitor cells.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Epigenetic rejuvenation of mesenchymal stromal cells derived from induced pluripotent stem cells.
Specimen part, Subject
View SamplesReprogramming of somatic cells is a valuable tool to understand the mechanisms of regaining pluripotency and further opens up the possibility of generating patient-specific pluripotent stem cells. Reprogramming of mouse and human somatic cells into pluripotent stem cells, designated as induced pluripotent stem (iPS) cells, has been possible with the expression of the transcription factor quartet Oct4 (also known as Pou5f1), Sox2, c-Myc, and Klf4. Considering that ectopic expression of c-Myc causes tumourigenicity in offspring and retroviruses themselves can cause insertional mutagenesis, the generation of iPS cells with a minimal number of factors may hasten the clinical application of this approach. Here, we show that adult mouse neural stem cells express higher endogenous levels of Sox2 and c-Myc than embryonic stem cells, and that exogenous Oct4 together with either Klf4 or c-Myc are sufficient to generate iPS cells from neural stem cells. These two-factor (2F) iPS cells are similar to embryonic stem cells at the molecular level, contribute to development of the germ line, and form chimeras. We propose that, in inducing pluripotency, the number of reprogramming factors can be reduced when using somatic cells that endogenously express appropriate levels of complementing factors.
Pluripotent stem cells induced from adult neural stem cells by reprogramming with two factors.
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