A Small-Molecule Inhibitor of Tgf-β Signaling Replaces Sox2 in Reprogramming by Inducing Nanog

Harvard Stem Cell Institute, Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.
Cell stem cell (Impact Factor: 22.27). 10/2009; 5(5):491-503. DOI: 10.1016/j.stem.2009.09.012
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ABSTRACT The combined activity of three transcription factors can reprogram adult cells into induced pluripotent stem cells (iPSCs). However, the transgenic methods used for delivering reprogramming factors have raised concerns regarding the future utility of the resulting stem cells. These uncertainties could be overcome if each transgenic factor were replaced with a small molecule that either directly activated its expression from the somatic genome or in some way compensated for its activity. To this end, we have used high-content chemical screening to identify small molecules that can replace Sox2 in reprogramming. We show that one of these molecules functions in reprogramming by inhibiting Tgf-beta signaling in a stable and trapped intermediate cell type that forms during the process. We find that this inhibition promotes the completion of reprogramming through induction of the transcription factor Nanog.

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Available from: Kyle M Loh, Jun 20, 2014
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    • "This hypothesis was based on our data that HDDCs could upregulate their epithelial phenotype after EMT inhibition and that MET was required to reprogram fibroblasts into iPSCs (Li et al., 2010b). For this protocol, we incubated HDDCs with A83- 01 and VPA, a histone deacetylase inhibitor shown to synergize with RepSox EMT inhibitor (Ichida et al., 2009), for 3 days prior to our R protocol. Compared to the R protocol, these HDDCs had higher INS, PDX1, and NEUROD mRNA expression without significantly different expression of other analyzed markers, including glucagon (Fig. 5A). "
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    • "One of the primary obstacles to the successful application of iPSCs for medical purposes is their low reprogramming efficiency . Significant effort has been devoted to enhancing induced reprogramming efficiency, including approaches focusing on the use of mRNA (Warren et al., 2010), small molecules (Ichida et al., 2009; Li and Rana, 2012; Maherali and Hochedlinger, 2009; Nichols et al., 2009; Silva et al., 2008; Yang et al., 2011b; Ying et al., 2008; Zhu et al., 2011), and microRNAs (Choi et al., 2011; Judson et al., 2009; Kim et al., 2011; Li and He, 2012; Li et al., 2011; Liao et al., 2011; Lipchina et al., 2011; Melton et al., 2010; Pfaff et al., 2011; Subramanyam et al., 2011; Yang and Rana, 2013; Yang et al., 2011a). However, detailed functional insight into the molecular basis of reprogramming is still lacking. "
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    • "Blocking TGFb is known to induce MET. Also, the use of an inhibitor of TGFb receptor 1 consistently facilitates reprogramming to iPSCs and was found to successfully replace one or more components of the OSKM cocktail – although not OCT4, the main regulator of somatic cell reprogramming (Ichida et al., 2009; Maherali and Hochedlinger, 2009; Li et al., 2010c; Radzisheuskaya and Silva, 2013). Interestingly, both OCT4 and SOX2 can directly activate the miR-200 cluster, and Box 3. b-catenin/WNT signaling plugs into the core pluripotency transcription factor network "
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