Project description:In order to identify genes that are activated in differentiating WT ESCs, but are missing in Tal-1-/- and Runx1-/- ESCs, and which might be involved in the generation of definitive hematopoietic progenitors and their specification thereafter, we performed microarray analyses on purified Flk-1+ cells, differentiated from these ESCs for 4, 5, and 6 days “in vitro”.
Project description:ES cells differentiated in the presence of the Wnt inhibitor DKK1 fail to express the transcription factor Snail and undergo EMT or mesoderm differentiation. We generated an ES cell line, A2.snail, that induced Snail expression upon addition of doxycycline addition. Microarrays were used to gain a global picture of Flk1- and Flk1+ cells generated one day after Snail was expressed during Wnt inhibition. A2.snail ES cells, which express Snail upon addition of doxycycline, were differentiated as embryoid bodies in differentiation media and DKK1. Snail-induced cultures uniquely develop a select population of Flk1+ cells. Total RNA was harvested from sorted control (no doxycycline) Flk1- cells and sorted Snail-induced (doxycycline at day 2) Flk1- and Flk1+ cells at day 3 of differentiation.
Project description:Blood and endothelial cells arise from hemangiogenic progenitors that are specified from FLK1-expressing mesoderm by the transcription factor ETV2. FLK1 mesoderm also contributes to other tissues, including vascular smooth muscle (VSM) and cardiomyocytes. However, the developmental process of FLK1 mesoderm generation and its derivatives and the lineage relationship among FLK1 mesoderm derivatives these tissues remain obscure. Recent single cell RNA-sequencing (scRNA-seq) studies of early stages of embryogenesis embryos, or in vitro differentiated human embryonic stem (ES) cells have differentiation provided unprecedented information on the spatiotemporal resolution of cells in embryogenesis. Nonetheless, these snapshots still nonetheless offer insufficient information on dynamic developmental processes due to inadvertently missing intermediate states and unavoidable batch effects. Here we performed scRNA-seq of mouse ES cells in asynchronous embryoid bodies (EBs), in vitro differentiated embryonic stem (ES) cells containing undifferentiated ES cells and its differentiated hemangiogenic progeny, as well as yolk sacs, the first hematopoietic extraembryonic tissue in developing embryo that contains hemangiogenic and VSM lineages. We captured a continuous developmental process from undifferentiated pluripotent cells to FLK1 mesoderm-derived tissues involved in hemangiogenesis. This continuous transcriptome map will benefit both basic and applied studies of mesoderm and its derivatives.
Project description:ES cells differentiated in the presence of the Wnt inhibitor DKK1 fail to express the transcription factor Snail and undergo EMT or mesoderm differentiation. We generated an ES cell line, A2.snail, that induced Snail expression upon addition of doxycycline addition. Microarrays were used to gain a global picture of Flk1- and Flk1+ cells generated one day after Snail was expressed during Wnt inhibition.
Project description:Transcription factors have long been recognised as powerful regulators of mammalian development, yet it is largely unknown how individual key regulators operate within wider regulatory networks. Here we have used a combination of global gene expression and chromatin-immunoprecipitation approaches across four ES-cell-derived populations of increasing haematopoietic potential to define the transcriptional programme controlled by Runx1, an essential regulator of blood cell specification. Integrated analysis of these complementary genome-wide datasets allowed us to construct a global regulatory network model, which suggested that core regulatory circuits are activated sequentially during blood specification, but will ultimately collaborate to control many haematopoietically expressed genes. Using the CD41/integrin alpha 2b gene as a model, cellular and in vivo studies showed that CD41 is controlled by both early and late circuits in fully specified blood cells, but initiation of CD41 expression critically depends on a later subcircuit driven by Runx1. Taken together, this study represents the first global analysis of the transcriptional programme controlled by any key haematopoietic regulator during the process of early blood cell specification. Moreover, the concept of interplay between sequentially deployed core regulatory circuits is likely to represent a design principle widely applicable to the transcriptional control of mammalian development. 4 samples (Runx1-/VE-cadherin+/Flk1+, Runx1+/VE-cadherin+/CD41+, Runx1+/VE-cadherin+/CD41- and Runx1+/VE-cadherin-/CD41+). 1 x 10^5 undifferentiated ES cells were cultured on confluent OP9 cell layers in 10-cm dishes to induce differentiation. After 6 days of ES cell differentiation, cultured cells were harvested for FACS analysis and sorting.
Project description:Previously, we reported that the transcription factor Mesp1 promotes the cell fates of cardiomyocytes, smooth muscle, and vascular endothelium. Recently, hematopoietic stem cells (HSCs) were shown to derive from hemogenic endothelium. Since Mesp1 regulates development of endothelium, it potentially could influence gene expression related to hematopoietic development. Our present fate mapping study found that Mesp1-cre efficiently labeled hematopoietic lineages in vivo. This result suggested that Mesp1 might be expressed in progenitors of the hematopoietic system, such as hemogenic endothelium. To test this, we purified Flk1+ Tie2+ endothelium derived from differentiating ES cells with or without Mesp1 induction, and used microarray expression analysis to identify genes strongly up-regulated by Mesp1. Embryonic stem (ES) cells harboring a doxycycline (dox)-inducible Mesp1 gene (A2lox.Mesp1) were differentiated as embryoid bodies for 5 days in the absence (-) or presence (+) of dox from day 2 to day 4. Flk1+Tie2+ endothelial cells were purified by cell sorting for RNA extraction and hybridization on Affymetrix microarrays.
Project description:We found that mouse ES cell-derived Flk1+ cells could be subdivided into three population by the expression of PDGFRa and CAR (Flk1+PDGFRa-CAR-, Flk1+PDGFRa-CAR+, and Flk1+PDGFRa+CAR+). Therefore, global gene expression analysis was perfomed by microarray to characterize these mesodermal subsets.
Project description:In order to identify genes that are activated in differentiating WT ESCs, but are missing in Tal-1-/- and Runx1-/- ESCs, and which might be involved in the generation of definitive hematopoietic progenitors and their specification thereafter, we performed microarray analyses on purified Flk-1+ cells, differentiated from these ESCs for 4, 5, and 6 days M-bM-^@M-^\in vitroM-bM-^@M-^]. Gene-expression profiling of three biological replicates was performed at days 4, 5, and 6 during the differentiation process of WT J1 ESCs (9 samples), and at day 6 during the differentiation process of either Runx1-/- J1 or Tal-1-/- J1 ESCs (3 samples each). Total RNA was extracted using the RNeasy Mini kit (Qiagen). The integrity and amount of isolated RNA was assessed for each sample using an Agilent 2100 Bioanalyzer (Agilent, Waldbronn, Germany) and a NanoDrop ND-1000 spectrophotometer (NanoDrop Technologies, Wilmington, DE). Complementary DNA was synthesized from 3-5 M-NM-<g total RNA, using reagents recommended in the technical manual GeneChip Expression Analysis (Affymetrix, Santa Clara, CA). The in vitro transcription, necessary for the synthesis of biotinylated complementary RNA (cRNA) was performed using the Enzo RNA Transcript Labeling kit (Affymetrix). Fifteen micrograms of fragmented cRNA of each sample were hybridized to nine Mouse Genome 430-2 arrays (Affymetrix). Hybridization was performed in a Hybridization Oven 640, and chips were washed and stained in the Fluidics Station 400 (both Affymetrix), according to procedure 2 as described in the technical manual. Finally, the arrays were scanned with a GeneChip Scanner 3000 using the GCOS software, both Affymetrix. All relevant GCOS data of quality checked microarrays were analyzed with High Performance Chip Data Analysis (HPCDA, unpublished), using the BioRetis database (www.bioretis-analysis.de), as described and validated previously (55). Used query parameters for database filtering process was described earlier several times (56). For hierarchical cluster analysis, we used the program Genes@Work (57) with gene vectors for normalization and Pearson w/mean for similarity measure. As cluster type, we used center of mass.
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.