Figure 3

Inhibition of Fgf signaling causes rapid loss of G1- and S-phase cell-cycle gene expression, and blocks S-phase progression. Wild-type embryos were treated with 10 μM SU5402 (D-F, J-L, M, N) or the carrier 0,125% DMSO (A-C, G-I, O, P) for 3 hours from 36 to 39 hpf. For BrdU stainings, after 3-hour treatment with either SU5402 or DMSO, embryos were injected with 10 mM BrdU solution into the yolk and incubated for 1 hour in the same solutions before fixation. SU5402 treatment strongly downregulated the expression of pea3 FGF signaling target (A, D), but had only a small effect on ptc1 expression in fin buds (B, E). SU5402 treatment also caused strong downregulation of cyclinD1 (C, F), pcna (G, J) and mcm5 (H, K). Expression of ra1 was not affected by SU5402 treatment (I, L). S-phase progression, as revealed by BrdU labelling, was strongly inhibited after SU5402 treatment, in comparison to control embryos (n = 10, at least 2 fin sections per embryo were analysed) (M, N).