Fig. 4
An Fgf–Wnt/β-catenin signaling interaction is necessary for differentiation of scale forming cells.
(A,B) Imaging sp7:EGFP over a five day treatment with 1 µM BGJ398 to inhibit Fgf receptors revealed completely arrested squamation (n = 8), whereas DMSO-treated control fish developed normally (n = 8). (A’,B’) BGJ398 treatment also arrested growth of individual scales. (C) hag/+ mutants overexpress Fgf8a and had disorganized differentiation of sp7:EGFP+ dSFCs (n = 6). (D) dSFCs did not appear in hag/+ mutant skin with hs:dkk1 induction (n = 12). (E) Loss of Eda signaling in nkt/nkt mutants did not prevent differentiation of sp7:EGFP+ scale forming cells, likely owing to residual Wnt activity in the skin (n = 12). Scale bars, 1 mm (A–E); 100 µm (A’, B’).