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. 2009 Oct 28;4(10):e7650. doi: 10.1371/journal.pone.0007650

Figure 8. Elevated Wnt/β-catenin signaling opposes cardiogenesis after specification.

Figure 8

(A) Animal cap expressing either CSKA-Wnt8 or LEF-β-catenin-GR were conjugated and dexamethasone was added as indicated. All treatments block cardiogenesis. (B) LEF-β-GR activated at st. 9 and st. 13 has no effect on Nkx2.5 and Tbx5 expression at st. 18. (C) The effect of various agonists on the Wnt/β-catenin pathway: LiCl and BIO cause strong transient activation, Wnt8 causes weak and sustained activation, and LEF-β-catenin-GR causes strong and prolonged effect. Siamois and Xnr3 expression was analysed 2 and 6 hours after excision of animal caps/Treatment with LiCl, BIO and Dex was immediately after the excision. (D) The expression of the LEF-β-catenin-GR fusion protein was analyzed by Western blotting for HA tag. The protein was expressed efficiently at all stages at which dexamethasone was added and it persists for many hours. (E, F) LiCl or BIO treatment at st. 9 has no effect on cardiac differentiation but induces skeletal muscle. Later treatment at st. 21 or 24 blocks cardiac differentiation, and treatment at st. 27 has no effect.