Chen B, Dodge ME, Tang W et al.Small molecule-mediated disruption of Wnt-dependent signaling in tissue regeneration and cancer. Nat Chem Biol 5:100-107

Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
Nature Chemical Biology (Impact Factor: 13). 01/2009; 5(2):100-107. DOI: 10.1038/nchembio.137


The pervasive influence of secreted Wnt signaling proteins in tissue homeostasis and tumorigenesis has galvanized efforts to identify small molecules that target Wnt-mediated cellular responses. By screening a diverse synthetic chemical library, we have discovered two new classes of small molecules that disrupt Wnt pathway responses; whereas one class inhibits the activity of Porcupine, a membrane-bound acyltransferase that is essential to the production of Wnt proteins, the other abrogates destruction of Axin proteins, which are suppressors of Wnt/-catenin pathway activity. With these small molecules, we establish a chemical genetic approach for studying Wnt pathway responses and stem cell function in adult tissue. We achieve transient, reversible suppression of Wnt/-catenin pathway response in vivo, and we establish a mechanism-based approach to target cancerous cell growth. The signal transduction mechanisms shown here to be chemically tractable additionally contribute to Wnt-independent signal transduction pathways and thus could be broadly exploited for chemical genetics and therapeutic goals.

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    • "This is in agreement with the primary function of RAB8B in ligand-receiving cells (Demir et al., 2013). Stronger inhibitory effects on Wnt3a-Gluc secretion were observed upon treatment with C59 (∼93% reduction), a Porcupine inhibitor (Chen et al., 2009), or by Gpr177 ablation in MEFs (∼97% reduction) (Fig. 2C). Notably, Fig. 2. Rab8a deletion reduces Wnt secretion. "
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    ABSTRACT: Communication between stem and niche supporting cells maintains the homeostasis of adult tissues. Wnt signaling is a crucial regulator of the stem cell niche, but the mechanism that governs Wnt ligand delivery in this compartment has not been fully investigated. We identified that Wnt secretion is partly dependent on Rab8a-mediated anterograde transport of Gpr177 (wntless), a Wnt-specific transmembrane transporter. Gpr177 binds to Rab8a, depletion of which compromises Gpr177 traffic, thereby weakening the secretion of multiple Wnts. Analyses of generic Wnt/β-catenin targets in Rab8a knockout mouse intestinal crypts indicate reduced signaling activities; maturation of Paneth cells - a Wnt-dependent cell type - is severely affected. Rab8a knockout crypts show an expansion of Lgr5(+) and Hopx(+) cells in vivo. However, in vitro, the knockout enteroids exhibit significantly weakened growth that can be partly restored by exogenous Wnts or Gsk3β inhibitors. Immunogold labeling and surface protein isolation identified decreased plasma membrane localization of Gpr177 in Rab8a knockout Paneth cells and fibroblasts. Upon stimulation by exogenous Wnts, Rab8a-deficient cells show ligand-induced Lrp6 phosphorylation and transcriptional reporter activation. Rab8a thus controls Wnt delivery in producing cells and is crucial for Paneth cell maturation. Our data highlight the profound tissue plasticity that occurs in response to stress induced by depletion of a stem cell niche signal. © 2015. Published by The Company of Biologists Ltd.
    Development 05/2015; 128(13). DOI:10.1242/dev.121046 · 6.46 Impact Factor
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    • "L.K. Briona et al. / Developmental Biology 403 (2015) 15–21 19 generally required for the regenerative response following injury. We therefore used the small molecule Wnt inhibitor IWR1, an Axin stabilizer that promotes ß-catenin degradation (Chen et al., 2009), to determine whether Wnt/ß-catenin pathway activity is required for neurogenesis following SCI. Our initial analysis determined that incubation in 35 mM IWR1 was sufficient to inhibit Wnt reporter expression after SCI without being lethal (Supplementary Fig. S1). "
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    ABSTRACT: Spinal cord injury results in permanent sensorimotor loss in mammals, in part due to a lack of injury-induced neurogenesis. The regeneration of neurons depends upon resident neural progenitors, which in zebrafish persist throughout the central nervous system as radial glia. However the molecular mechanisms regulating spinal cord progenitors remain uncharacterized. Wnt/ß-catenin signaling is necessary for the regenerative response of multiple tissues in zebrafish as well as other vertebrates, but it is not known whether the pathway has a role in spinal cord regeneration. Here we show that spinal radial glia exhibit Wnt/ß-catenin activity as they undergo neurogenesis following transection. We then use Cre-mediated lineage tracing to label the progeny of radial glia and show that Wnt/ß-catenin signaling is required for progenitors to differentiate into neurons. Finally, we show that axonal regrowth after injury also requires Wnt/ß-catenin signaling, suggesting coordinated roles for the pathway in functional recovery. Our data thus establish Wnt/ß-catenin pathway activation as a necessary step in spinal cord regeneration. Copyright © 2015. Published by Elsevier Inc.
    Developmental Biology 04/2015; 403(1). DOI:10.1016/j.ydbio.2015.03.025 · 3.55 Impact Factor
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    • "To monitor these processes in vitro, we established EpiSCs carrying the T-GFP reporter for the primitive streak marker Brachyury by differentiating T-GFP ESCs (Fehling et al., 2003) into EpiSCs by culture in FGF2 and ACTIVIN. We included IWP2, a small molecule inhibitor that blocks the biosynthesis of mature WNT proteins (Chen et al., 2009), to increase the efficiency of differentiation (ten Berge et al., 2011). Phenotypic and functional assays verified the complete differentiation (Figures S1A–S1D available online). "
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    ABSTRACT: Therapeutic application of human embryonic stem cells (hESCs) requires precise control over their differentiation. However, spontaneous differentiation is prevalent, and growth factors induce multiple cell types; e.g., the mesoderm inducer BMP4 generates both mesoderm and trophoblast. Here we identify endogenous WNT signals as BMP targets that are required and sufficient for mesoderm induction, while trophoblast induction is WNT independent, enabling the exclusive differentiation toward either lineage. Furthermore, endogenous WNT signals induce loss of pluripotency in hESCs and their murine counterparts, epiblast stem cells (EpiSCs). WNT inhibition obviates the need to manually remove differentiated cells to maintain cultures and improves the efficiency of directed differentiation. In EpiSCs, WNT inhibition stabilizes a pregastrula epiblast state with novel characteristics, including the ability to contribute to blastocyst chimeras. Our findings show that endogenous WNT signals function as hidden mediators of growth factor-induced differentiation and play critical roles in the self-renewal of hESCs and EpiSCs. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Stem Cell Reports 01/2015; 4(1):114-128. DOI:10.1016/j.stemcr.2014.11.007 · 5.37 Impact Factor
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