Fig. 1: Activation of Wnt signal induces midbrain characteristics in human ESC-derived NPCs.

a Efficient induction of neural rosette cells from human ESCs by co-treatment with dorsomorphin and SB431542. b Strong immunoreactivity for SOX1 and Nestin in neural rosette cells. Morphology of neural rosette cells expanding in either the absence (c) or the presence of 1 μM BIO (d). e NPCs treated with BIO maintained immunoreactivity for SOX1 and Nestin. f Treatment with BIO upregulated EN1 expression and downregulated expressions of BF1 and GBX2 in dose-dependent manner. g BIO treatment significantly increased the number of EN1-positive neural cells. h The inductive effect of BIO treatment on midbrain fate appeared to be more specific than that of FGF8. i Expression pattern of another set of regional markers (SIX3 for forebrain; PAX2 for midbrain; and HOXA2 for hindbrain) supported the midbrain-biased fate of NPCs treated with BIO. Treatment with other known GSK3 inhibitors, 1-AKP (j) and LiCl (k), resulted in regionalization comparable to BIO treatment. l Treating NPCs with Wnt antagonists (100 ng/ml DKK-1 and 500 ng/ml frizzled-5) downregulated the endogenous level of EN1 transcript in NPCs. m Immunoblot for β-catenin and EN1 protein after introduction of two different β-catenin-specific shRNAs (shRNA-1 and shRNA-2). EN1 protein level was directly downregulated by β-catenin knockdown. β-actin was a loading control. All data are expressed as mean ± S.E.M. Statistical significance was estimated using Student’s t test (g, i, j, and k) or one-way ANOVA (f, h, and l) from at least three independent experiments; *p < 0.05, **p < 0.01. Scale bar: 200 μm for a, c, and d; 50 μm for b, e, and g