The study of induced pluripotency often relies on experimental approaches that average measurements across a large population of cells, the majority of which do not become pluripotent. Here we used high-resolution, time-lapse imaging to trace the reprogramming process over 2 weeks from single mouse embryonic fibroblasts (MEFs) to pluripotency factor-positive colonies. This enabled us to calculate a normalized cell-of-origin reprogramming efficiency that takes into account only the initial MEFs that respond to form reprogrammed colonies rather than the larger number of final colonies. Furthermore, this retrospective analysis revealed that successfully reprogramming cells undergo a rapid shift in their proliferative rate that corresponds to a reduction in cellular area. This event occurs as early as the first cell division and with similar kinetics in all cells that form induced pluripotent stem (iPS) cell colonies. These data contribute to the theoretical modeling of reprogramming and suggest that certain parts of the reprogramming process follow defined rather than stochastic steps.
Dynamic single-cell imaging of direct reprogramming reveals an early specifying event.
Specimen part
View SamplesType I IFN-signaling suppresses an excessive IFN-{gamma} response and prevents lung damage and chronic inflammation following Pneumocystis (PC)-infection and clearance in CD4 T cell-competent mice.
Type-I IFN signaling suppresses an excessive IFN-gamma response and thus prevents lung damage and chronic inflammation during Pneumocystis (PC) clearance in CD4 T cell-competent mice.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Reprogramming factor expression initiates widespread targeted chromatin remodeling.
Specimen part
View SamplesExpression profiles generated during dissection of the molecular mechanisms underlying direct reprogramming of somatic cells to a pluripotent state (induced pluripotent stem cells, iPS).
Dissecting direct reprogramming through integrative genomic analysis.
No sample metadata fields
View SamplesThe retinoblastoma cell cycle regulator pRb and the two related proteins p107 and p130 are thought to suppress cancer development both by inhibiting the G1/S transition of the cell cycle in response to growth-arrest signals and by promoting cellular differentiation. Here, we investigated the phenotype of Rb family triple knock-out (TKO) embryonic stem cells as they differentiate in vivo and in culture. Confirming the central role of the Rb gene family in cell cycle progression, TKO mouse embryos did not survive past mid-gestation and differentiating TKO cells displayed increased proliferation and cell death. However, patterning and cell fate determination were largely unaffected in these TKO embryos. Furthermore, a number of TKO cells, including in the neural lineage, were able to exit the cell cycle in G1 and terminally differentiate. This ability of Rb family TKO cells to undergo cell cycle arrest was associated with the repression of target genes for the E2F6 transcription factor, uncovering a pRb-independent control of the G1/S transition of the cell cycle. These results show that the Rb gene family is required for proper embryonic development but is not absolutely essential to induce G1 arrest and differentiation in certain lineages.
G1 arrest and differentiation can occur independently of Rb family function.
No sample metadata fields
View SamplesThe generation of sufficient numbers of mature ventricular myocytes for effective cell-based therapy is a central barrier for cardiac regenerative medicine. Here we demonstrate that induced pluripotent stem cells (iPSCs) can be derived from murine ventricular myocytes, and consistent with other reports of iPSCs derived from various somatic cell types, ventricular myocyte derived iPSCs (ViPSCs) exhibit a markedly higher propensity to differentiate into beating cardiomyocytes as compared to genetically-matched embryonic stem cells (ESCs) or iPSCs derived from tail-tip fibroblasts. Strikingly, ViPSC-derived cardiomyocytes form up to 99% ventricular myocytes suggesting that ventricular myocyte-derived iPSCs may be a viable strategy to generate specific cardiomyocyte subtypes for cell-based therapies. The enhanced ventricular myogenesis in ViPSCs is mediated via increased numbers of cardiovascular progenitors at early stages of differentiation. In order to investigate the mechanism of enhanced ventricular myogenesis from ViPSCs, we performed global gene expression and DNA methylation analysis, which revealed a distinct epigenetic signature that may be involved in specifying the ventricular myocyte fate in pluripotent stem cells.
Highly efficient derivation of ventricular cardiomyocytes from induced pluripotent stem cells with a distinct epigenetic signature.
Specimen part
View SamplesCytosine methylation is an epigenetic mark usually associated with gene repression. Despite a requirement for de novo DNA methylation for differentiation of embryonic stem cells, its role in somatic stem cells is unknown. Using conditional ablation, we show that loss of either, or both, Dnmt3a or Dnmt3b, progressively impedes hematopoietic stem cell (HSC) differentiation during serial in vivo passage. Concomitantly, HSC self-renewal is immensely augmented in absence of either Dnmt3, particularly Dnmt3a. Dnmt3-KO HSCs show upregulation of HSC multipotency genes and downregulation of early differentiation factors, and the differentiated progeny of Dnmt3-KO HSCs exhibit hypomethylation and incomplete repression of HSC-specific genes. HSCs lacking Dnmt3a manifest hyper-methylation of CpG islands and hypo-methylation of genes which are highly correlated with human hematologic malignancies. These data establish that aberrant DNA methylation has direct pathologic consequences for somatic stem cell development, leading to inefficient differentiation and maintenance of a self-renewal program.
Dnmt3a is essential for hematopoietic stem cell differentiation.
Sex, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Age- and pregnancy-associated DNA methylation changes in mammary epithelial cells.
Sex, Age, Specimen part
View SamplesGlucocorticoids (GC) are in most chemotherapy protocols for lymphoid malignancies, particularly childhood acute lymphoblastic leukaemia (ALL) for their ability to induce apoptosis in malignant blast. The underlying mechanism, however, has so far only been investigated in model systems. This study comprises Affymetrix hgu133 plus 2.0 analyses of
Identification of glucocorticoid-response genes in children with acute lymphoblastic leukemia.
No sample metadata fields
View SamplesTranscriptional profiling of the zebrafish embryonic host response to a systemic bacterial infection with Salmonella typhimurium (strain SL1027); comparison between traf6 knock-down and control morpholino treated embryos. Overall design: All infection experiments were performed using mixed egg clutches of ABxTL strain zebrafish. Embryos injected with traf6 morpholino or a 5bp mismatch control morpholino were staged at 27 hours post fertilization (hpf) by morphological criteria and approximately 250 cfu of DsRed expressing Salmonella bacteria were injected into the caudal vein close to the urogenital opening. As a control an equal volume of PBS was likewise injected. Pools of 20-40 infected and control embryos were collected 8 hours post infection (hpi). The whole procedure was preformed in triplicate on separate days. Total RNA of the biological triplicates was pooled using equal amounts of RNA prior to RNAseq library preparation.
Transcriptome analysis of Traf6 function in the innate immune response of zebrafish embryos.
No sample metadata fields
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