Figure 2

Erk5-Klf2a-Wnt signaling within AVC endocardium is essential for valvulogenesis

(A–D) Single confocal z section plane images of the superior AVC endocardium at 54 hpf. (A and B) The endothelial-specific knockdown of canonical Wnt signaling prevents AVC endocardial cells from ingressing into the cardiac jelly. (A) Presence of a TCF-positive ingressed cell when TCF is not blocked (asterisk). Note the presence of TCF-positive cells in the myocardium of treated hearts (B), which confirms the tissue-specificity of this treatment. (C and D) TCF-positive endocardial cells (asterisks in C) are absent in in klf2a^sh317;klf2b^pbb42 double mutants.

(E–J) Single confocal z section plane images of the superior AVC endocardium at 54 hpf. (E–G and H–J) Quantification of Klf2a:YFP net fluorescent intensity in the superior AVC endocardium of DMSO- and XMD8-92-treated embryos at 48 hpf (E, F, and G) (DMSO-treated, n = 8 embryos; XMD8-92-treated, n = 9 embryos) and 54 hpf (H–J) (DMSO-treated, n = 10 embryos; XMD8-92-treated, n = 8 embryos). Single values are shown in a boxplot. Lines inside the box represent mean values. The lower and the upper whiskers indicate minimum and maximum values, respectively (^∗p < 0.05 and ^∗∗∗∗p < 0.0001 by unpaired Student’s t test). (E′, F′, H′, and I′) The presence of single TCF-positive cells (asterisks in E′ and H′) is prevented by treating embryos with XMD8-92 (F′ and I′). Scale bars, 5 μm