C57BL/6J mice were maintained according to protocols approved by the Animal Care Committee of the University of British Columbia following guidelines established by the Canadian Council on Animal Care. Endoderm isolation was previously described.12 Hepatoblast isolation is described in the Supporting Methods. Adult liver was obtained

from a 6-month-old female mouse. Small RNA preparation and library construction was previously described.13 Libraries were sequenced on Illumina GAIIx. Reads were aligned to NCBI37/mm9 reference genome and miRNA annotation was based on miRBase V15. Read processing, quantification, and annotation was previously described.13 Expression of miRNAs was normalized to total reads aligned to genome and expressed as reads per million (RPM). Two replicates from foregut, two from hepatoblasts, and one from selleck screening library adult liver were generated. The expression correlation between replicates was r2 = 0.9282 and r2 = 0.9718 Decitabine for foregut and hepatoblasts, respectively (Supporting Fig. S1A). We used one replicate for further analysis. miRNAs expressed at greater than 10 RPM were used in K-means clustering analysis.14 Novel miRNA prediction was previously described.13 RNA was extracted using mirVana miRNA isolation kit (Ambion). Real-time quantification was performed

using TaqMan MicroRNA Assays (Applied Biosystems) or SYBR Green (Roche) according to the manufacturer’s instructions. All expression results were normalized to U6 or Actin for miRNA and gene expression, respectively. The mir302b overexpression vector, pCMV-mir302b-IRES-GFP (302b_OE), and its control vector, pCMV-mir-IRES-GFP (Ctrl_OE), were purchased from Origene. A lentiviral-mediated gene expression system, including mir302b expression vector, pCDH302b,

and its control vector, pCDH, was purchased 上海皓元 from SBI. The mir20a knockdown vector, pCAG-d2eGFP-20a (20a_KD), and its control vector, pCAG-d2eGFP-Cxcr4 (Ctrl_KD), were subcloned from pCMV-d2eGFP-20a and pCMV-d2eGFP-Cxcr4,15 respectively (Addgene). Wildtype or mutant 3′ untranslated region (UTR) miRNA targets were cloned into pmirGLO (Promega). Tgfbr2 expression vectors, pBOS-Tgfbr2 and pBOS-Tgfbr2(Dominant negative, DN), were subcloned from pCMV5-Tgfbr2 and pCMV5-Tgfbr2(DN),16 respectively. 3TP-lux was described previously.16 TK-Renilla controlled for transfection efficiency. Western results were quantified by ImageJ. Luciferase assay is described in the Supporting Methods. ESC differentiation was previously described.17 Probes for WISH were obtained from Exiqon and experiments were performed according to Sweetman’s protocol18 at a temperature of 20° below the melting temperature of probes. No probe and mir29a served as negative controls (Fig. S2). All data presented are representative of at least three independent experiments unless indicated otherwise.