Article

A Temporal Chromatin Signature in Human Embryonic Stem Cells Identifies Regulators of Cardiac Development

Department of Pathology, University of Washington, Seattle, WA 98109, USA
Cell (Impact Factor: 32.24). 09/2012; 151(1):221-32. DOI: 10.1016/j.cell.2012.08.027
Source: PubMed

ABSTRACT

Directed differentiation of human embryonic stem cells (ESCs) into cardiovascular cells provides a model for studying molecular mechanisms of human cardiovascular development. Although it is known that chromatin modification patterns in ESCs differ markedly from those in lineage-committed progenitors and differentiated cells, the temporal dynamics of chromatin alterations during differentiation along a defined lineage have not been studied. We show that differentiation of human ESCs into cardiovascular cells is accompanied by programmed temporal alterations in chromatin structure that distinguish key regulators of cardiovascular development from other genes. We used this temporal chromatin signature to identify regulators of cardiac development, including the homeobox gene MEIS2. Using the zebrafish model, we demonstrate that MEIS2 is critical for proper heart tube formation and subsequent cardiac looping. Temporal chromatin signatures should be broadly applicable to other models of stem cell differentiation to identify regulators and provide key insights into major developmental decisions.

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    • "Among key findings were the activation of Wnt, HH, and TGF gene families, similar to our results, as well as differentiation associated increases in transcription coupled with increased promoter H3K4me3 and TSS downstream H3K36me3. These modifications are well known to correlate with decreased promoter DNA methylation and increased intragenic DNA methylation (Baubec et al., 2015, Morselli et al., 2015, Paige et al., 2012), respectively, in agreement with results from our study. "
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    ABSTRACT: The directed differentiation of human cardiomyocytes (CMs) from pluripotent cells provides an invaluable model for understanding mechanisms of cell fate determination and offers considerable promise in cardiac regenerative medicine. Here, we utilize a human embryonic stem cell suspension bank, produced according to a good manufacturing practice, to generate CMs using a fully defined and small molecule-based differentiation strategy. Primitive and cardiac mesoderm purification was used to remove non-committing and multi-lineage populations and this significantly aided the identification of key transcription factors, lncRNAs, and essential signaling pathways that define cardiomyogenesis. Global methylation profiles reflect CM development and we report on CM exon DNA methylation “memories” persisting beyond transcription repression and marking the expression history of numerous developmentally regulated genes, especially transcription factors.
    Full-text · Article · Jan 2016 · EBioMedicine
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    • "In a second stage, WNT signaling is blocked on days 2–3 using the small molecule inhibitor IWP-2 (Figure 1A; Chen et al., 2009). This treatment promoted the exit from self-renewal and the sequential induction of mesoderm by days 1–2, formation of a putative cardiac precursor cell identity by day 4, and, from day 5 onward, induction of an early cardiomyocyte-like fate (Figures 1B and 1C; Paige et al., 2012). The protocol routinely gave rise to monolayers of spontaneously beating cells by day 6 (Movie S1). "

    Full-text · Dataset · Jan 2016
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    • "In a second stage, WNT signaling is blocked on days 2–3 using the small molecule inhibitor IWP-2 (Figure 1A; Chen et al., 2009). This treatment promoted the exit from self-renewal and the sequential induction of mesoderm by days 1–2, formation of a putative cardiac precursor cell identity by day 4, and, from day 5 onward, induction of an early cardiomyocyte-like fate (Figures 1B and 1C; Paige et al., 2012). The protocol routinely gave rise to monolayers of spontaneously beating cells by day 6 (Movie S1). "
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    ABSTRACT: Cardiac induction requires stepwise integration of BMP and WNT pathway activity. Human embryonic stem cells (hESCs) are developmentally and clinically relevant for studying the poorly understood molecular mechanisms downstream of these cascades. We show that BMP and WNT signaling drive cardiac specification by removing sequential roadblocks that otherwise redirect hESC differentiation toward competing fates, rather than activating a cardiac program per se. First, BMP and WNT signals pattern mesendoderm through cooperative repression of SOX2, a potent mesoderm antagonist. BMP signaling promotes miRNA-877 maturation to induce SOX2 mRNA degradation, while WNT-driven EOMES induction transcriptionally represses SOX2. Following mesoderm formation, cardiac differentiation requires inhibition of WNT activity. We found that WNT inhibition serves to restrict expression of anti-cardiac regulators MSX1 and CDX2/1. Conversely, their simultaneous disruption partially abrogates the requirement for WNT inactivation. These results suggest that human cardiac induction depends on multi-stage repression of alternate lineages, with implications for deriving expandable cardiac stem cells.
    Full-text · Article · Dec 2015 · Cell stem cell
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