Article

Core Transcriptional Regulatory Circuitry in Human Embryonic Stem Cells

Department of Molecular and Cell Biology, Harvard University, Cambridge, Massachusetts, United States
Cell (Impact Factor: 32.24). 10/2005; 122(6):947-56. DOI: 10.1016/j.cell.2005.08.020
Source: PubMed

ABSTRACT

The transcription factors OCT4, SOX2, and NANOG have essential roles in early development and are required for the propagation of undifferentiated embryonic stem (ES) cells in culture. To gain insights into transcriptional regulation of human ES cells, we have identified OCT4, SOX2, and NANOG target genes using genome-scale location analysis. We found, surprisingly, that OCT4, SOX2, and NANOG co-occupy a substantial portion of their target genes. These target genes frequently encode transcription factors, many of which are developmentally important homeodomain proteins. Our data also indicate that OCT4, SOX2, and NANOG collaborate to form regulatory circuitry consisting of autoregulatory and feedforward loops. These results provide new insights into the transcriptional regulation of stem cells and reveal how OCT4, SOX2, and NANOG contribute to pluripotency and self-renewal.

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Available from: Roshan Kumar, Sep 15, 2014
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    • "Oct4, Sox2 and Nanog belong to this transcriptional circuit that plays a pivotal role in self-renewal and maintenance of pluripotency (Chen et al., 2008;Chambers and Tomlinson, 2009;He et al., 2009;Pauklin et al., 2011). In concert with Oct4 and Sox2, Nanog governs pluripotent features in mouse and human cells (Boyer et al., 2005;Loh et al., 2006) by occupying the promoters of active genes encoding transcription factors, signal transduction components, and chromatin-modifying enzymes. Expression of Oct4 and Sox2 is relatively homogeneous in pluripotent cells whereas Nanog exhibits a heterogeneous expression (Singh et al., 2007), with cells having elevated levels of Nanog exhibiting efficient self-renewal. "
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    ABSTRACT: A comprehensive analysis of the molecular network of cellular factors establishing and maintaining pluripotency as well as self renewal of pluripotent stem cells is key for further progress in understanding basic stem cell biology. Nanog is necessary for the natural induction of pluripotency in early mammalian development but dispensable for both, its maintenance as well as its artificial induction. To gain further insight into the molecular activity of Nanog we analyzed the gain-of-function of Nanog in various cell models employing a recently developed biologically active recombinant cell-permeant protein, Nanog-TAT. We found that Nanog enhances proliferation of both, NIH 3T3 as well as primary fibroblast cells. Nanog transduction into primary fibroblasts results in suppression of senescence‑associated β‑galactosidase activity. Investigation of cell cycle factors revealed that transient activation of Nanog correlates with consistent down-regulation of cell cycle inhibitor p27(KIP1). By chromatin immunoprecipitation analysis we confirmed bona fide Nanog binding sites upstream to the p27(KIP1) gene, establishing a direct link between physical occupancy and functional regulation. Our data demonstrates that Nanog enhances proliferation of fibroblasts via transcriptional regulation of cell cycle inhibitor p27 gene.
    Preview · Article · Jan 2016 · Journal of Cell Science
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    • "Octamer-binding transcription factor 4 (OCT4) and NANOG are transcription factors that mutually interact to regulate self-renewal and maintenance of pluripotency in embryonic stem (ES) cells [Boyer et al., 2005; Chambers et al., 2007; Mitsui et al., 2003; Niwa et al., 2000]. Thomson JA et al. have reported transduction of OCT4, SOX2, NANOG, and LIN28-induced human fibroblasts to pluripotent stem cells [Yu et al., 2007]. "
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    ABSTRACT: Mesenchymal stem cell (MSC)-conditioned medium (MSC-CM) has been reported to enhance wound healing. Exosomes contain nucleic acids, proteins, and lipids, and function as an intercellular communication vehicle for mediating some paracrine effects. However, the function of MSC-exosomes (MSC-exo) remains elusive. In this study, we isolated human placenta MSC (PlaMSC)-derived exosomes (PlaMSC-exo) and examined their function in vitro. PlaMSCs were isolated from human term placenta using enzymatic digestion. PlaMSC-exo were prepared from the conditioned medium of PlaMSC (PlaMSC-CM) by ultracentrifugation. The expression of stemness-related genes, such as OCT4 and NANOG, in normal adult human dermal fibroblasts (NHDF) after incubation with PlaMSC-exo was measured by real-time reverse transcriptase PCR analysis (real-time PCR). The effect of PlaMSC-exo on Oct4 transcription activity was assessed using Oct4-EGFP reporter mice-derived dermal fibroblasts. The stimulating effects of PlaMSC-exo on osteoblastic and adipogenic differentiation of NHDF were evaluated by alkaline phosphatase (ALP), and Alizarin red S- and oil red O-staining, respectively. The expression of osteogenic and adipogenic related genes was also assessed by real-time PCR. The treatment of NHDF with PlaMSC-exo significantly upregulated OCT4 and NANOG mRNA expression. PlaMSC-exo also enhanced Oct4 transcription. The NHDF treated with PlaMSC-exo exhibited osteogenic and adipogenic differentiation of NHDF in osteogenic and adipogenic induction media. PlaMSC-exo increase the expression of OCT4 and NANOG mRNA in fibroblasts. As a result, PlaMSC-exo influence the differentiation competence of fibroblasts to both osteoblastic and adipogenic differentiation. It shows a new feature of MSCs and the possibility of clinical application of MSC-exo. This article is protected by copyright. All rights reserved.
    Full-text · Article · Dec 2015 · Journal of Cellular Biochemistry
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    • "The pluripotency regulators OCT4, NANOG, and SOX2 form a core transcription regulatory network through auto-and reciprocal activations at the transcription level, which is believed to be responsible for the maintenance of human embryonic stem cell (hESC) pluripotency (Boyer et al., 2005). At the same time, multiple protein factors belonging to a diversity of functional categories, such as transcription factors, epigenetic factors, and signaling components, work cooperatively to form an expanded pluripotency factor network that supports the core pluripotency network (Boyer et al., 2005). In contrast to the well-defined core network, our knowledge of this expanded pluripotency network, including its components, the interactions between these components, and the mechanism of interaction between the expanded network and the core network, remains insufficient. "
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    ABSTRACT: Chemical biology methods such as high-throughput screening (HTS) and affinity-based target identification can be used to probe biological systems on a biomacromolecule level, providing valuable insights into the molecular mechanisms of those systems. Here, by establishing a human embryonal carcinoma cell-based HTS platform, we screened 171,077 small molecules for regulators of pluripotency and identified a small molecule, Displurigen, that potently disrupts hESC pluripotency by targeting heat shock 70-kDa protein 8 (HSPA8), the constitutively expressed member of the 70-kDa heat shock protein family, as elucidated using affinity-based target identification techniques and confirmed by loss-of-function and gain-of-function assays. We demonstrated that HSPA8 maintains pluripotency by binding to the master pluripotency regulator OCT4 and facilitating its DNA-binding activity.
    Full-text · Article · Nov 2015 · Stem Cell Reports
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