Tfap2a regulates the level of Fgf and Notch Signaling in the otic vesicle.
(A-V) Whole-mount images (dorsal up, anterior left) showing dorsolateral views of the otic vesicle (outlined). (A-R) Expression of the indicated genes in wild-type embryos, hs:tfap2a embryos and tfap2a-/- mutants (A-I) or tfap2a morphants (J-R) at 26 hpf (A-L, P-R) and 28 (M-O) hpf. (S, T) Cross-sections (dorsal up, medial left) passing through the utricular macula show spry4 expression at 28 hpf in a control embryo and tfap2a-/- mutant. (U-X) Whole-mounts showing expression of etv5b at 26 hpf. Activation of hs:tfap2a diminishes etv5b expression (U, V), activation of hs:fgf8 leads to global upregulation of etv5b (W), and co-activation of hs:fgf8 and hs:tfap2a restores etv5b to near normal (X). (Y) Cross-sections (dorsal up, medial left) passing just posterior to the utricular macula showing ngn1 at 24 hpf following a 35°C heat shock at 23 hpf. Reduction in the ngn1 domain caused by knockdown of tfap2a is rescued by weak activation of hs:dnfgfr1. (Z) Mean and standard deviation of the total number of ngn1 positive cells in the otic epithelium at 24 hpf for the genotypes and knockdowns indicated in the color key (counted from serial sections, n = 3–6 ears per time point). Asterisks (*) indicate statistically significant differences between the groups indicated in brackets.