Wnt-mediated self-renewal of neural stem/progenitor cells. Proc Natl Acad Sci U S A

Howard Hughes Medical Institute, Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 12/2008; 105(44):16970-5. DOI: 10.1073/pnas.0808616105
Source: PubMed


In this work we have uncovered a role for Wnt signaling as an important regulator of stem cell self-renewal in the developing brain. We identified Wnt-responsive cells in the subventricular zone of the developing E14.5 mouse brain. Responding cell populations were enriched for self-renewing stem cells in primary culture, suggesting that Wnt signaling is a hallmark of self-renewing activity in vivo. We also tested whether Wnt signals directly influence neural stem cells. Using inhibitors of the Wnt pathway, we found that Wnt signaling is required for the efficient cloning and expansion of single-cell derived populations that are able to generate new stem cells as well as neurons, astrocytes, and oligodendrocytes. The addition of exogenous Wnt3a protein enhances clonal outgrowth, demonstrating not only a critical role for the Wnt pathway for the regulation of neurogenesis but also its use for the expansion of neural stem cells in cell culture and in tissue engineering.

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    • "In contrast to induced pluripotent stem cells and embryonic stem cells, adult stem cells are not easily propagated and expanded. Selfrenewal/expansion has been reported for only a few types of adult stem cells, including neural (Kalani et al., 2008), intestinal (Barker et al., 2007), and liver stem cells (Huch et al., 2013), but the long-term functional activity of these cultured cells remains to be assessed. Therefore, the aim of the current study is to investigate the expansion potential of fully functional murine SG stem cells. "
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    • "Research to produce a population of cells in vitro that recapitulate the differentiated progeny seen in the intact nervous system has defined a " neural stem cell " (NSC), which is a selfrenewing cell whose progeny can produce neurons, oligodendrocytes and astrocytes (Fujita, 2003). In the embryonic neural tube these cells reside in the ventricular zone (or subventricular zone in the developing cerebral cortex), and in both the embryo and in NSC cultures, these cells are activated to produce new progeny by the integration of a number of signaling pathways, such as Sonic Hedgehog, BMP, Wnt/Catenin, Notch, and FGF (Fig. 1; Brault et al., 2001; Dahmane et al., 2001; Kalani et al., 2008; Mizutani et al., 2007; Ohtsuka et al., 2001; Palma and Ruiz i Altaba, 2004; Zechner et al., 2003). In both the embryo and in NSC cultures, the self-renewal ability of these cells is regulated by numerous transcription factors, including Hes, Sox, Bmi1, Tlx, and Gli proteins (Fig. 1; Ahmed et al., 2009; Bylund et al., 2003; Collignon et al., 1996; Fuccillo et al., 2006; Gaiano et al., 2000; Hatakeyama et al., 2004;Ishibashi et al., 1995;Miyagi et al., 2008;Molofsky et al., 2005; Palma and Ruiz i Altaba, 2004;Sun et al., 2007;Wood and Episkopou, 1999). "
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    • "We found that Zrf1 is essential for the establishment and maintenance of correct levels of selected Wnt ligands in NPCs. Although autocrine/paracrine Wnt signaling sustained by endogenously produced Wnt ligands has been previously reported to be crucial for NPC self-renewal (Chenn and Walsh 2002; Kalani et al. 2008; Wexler et al. 2009), molecular mechanisms regulating the expression of Wnt ligands in NPCs have not yet been studied in detail. "
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    ABSTRACT: The molecular mechanisms underlying specification from embryonic stem cells (ESCs) and maintenance of neural progenitor cells (NPCs) are largely unknown. Recently, we reported that the Zuotin-related factor 1 (Zrf1) is necessary for chromatin displacement of the Polycomb-repressive complex 1 (PRC1). We found that Zrf1 is required for NPC specification from ESCs and that it promotes the expression of NPC markers, including the key regulator Pax6. Moreover, Zrf1 is essential to establish and maintain Wnt ligand expression levels, which are necessary for NPC self-renewal. Reactivation of proper Wnt signaling in Zrf1-depleted NPCs restores Pax6 expression and the self-renewal capacity. ESC-derived NPCs in vitro resemble most of the characteristics of the self-renewing NPCs located in the developing embryonic cortex, which are termed radial glial cells (RGCs). Depletion of Zrf1 in vivo impairs the expression of key self-renewal regulators and Wnt ligand genes in RGCs. Thus, we demonstrate that Zrf1 plays an essential role in NPC generation and maintenance.
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