Fig. 4

Wnt signaling functions downstream of the FGF pathway in regulation of foxj1a expression and cilia formation. (A-D) Ectopic expression of Wnt ligands restores foxj1a levels in embryos with reduced FGF signaling. DFC^{fgfr1 MO} embryos exhibited downregulated foxj1a expression in DFCs (B; 17/18) compared with controls (A). Co-injection of wnt8a RNA with fgfr1 MO restored foxj1a expression (C; 16/19). Ectopic expression of wnt8a RNA alone had no apparent effect on foxj1a expression (D). (E-H) Ectopic expression of FGF ligands fails to restore foxj1a expression in embryos with reduced Wnt signaling. Downregulated foxj1a expression in DFC^{fzd10 MO} embryos (F) was not restored by co-injection of fgf8a RNA (G). Ectopic expression of fgf8a RNA alone had no apparent effect on foxj1a expression (H). Shown are ventral views of 90-95% epiboly staged embryos. (I,J) Ectopic expression of Wnt ligands partially rescues cilia length defects in embryos with reduced FGF signaling. Shown are quantification of cilia length (I) and cilia number (J). Approximately 12-20 embryos were analyzed for each group. Data are represented as mean±s.d. ^*P<0.01. NS, not significant (P>0.05).