Fig. 1.

Fig. 1. Egr3 is required for cardiac valve formation.

(A) Schematic of hearts isolated for scRNA-seq; valve EdCs (magenta), nonvalve EdCs (blue). (B) scRNA-seq of EdCs from 50 and 80 hpf dissected zebrafish hearts. (C) Dot plot of 30 most differentially expressed genes in valve compared with nonvalve EdCs. (D) Schematic of generation of egr3 full locus deletion (bns522) and Δ11 (bns577) alleles. (E and F) Brightfield images of egr3^+/+ and egr3^−/− sibling larvae at 80 hpf; red arrowheads point to pericardial edema. (G) Confocal images of representative hearts from 72 and 96 hpf egr3^+/+ and egr3^−/− sibling larvae. (H) Percentage of egr3^+/+ and egr3^−/− sibling larvae with a superior valve leaflet and without a superior valve leaflet (i.e., endocardial monolayer) at 72 and 96 hpf; seven and four independent experiments, respectively. (I) AV retrograde blood flow shown as a fraction of three cardiac cycles; n = 6, 11, and 3; one experiment; mean ± SEM, one-way ANOVA followed by Tukey’s post hoc test. (J) Peripheral circulation in the caudal vein plexus at 80 hpf, one experiment. (K) Confocal images of representative OFT valves from 96 hpf egr3^+/+ and egr3^−/− sibling larvae. (L) Percentage of egr3^+/+ and egr3^−/− sibling larvae with and without forming OFT leaflets at 96 hpf; four independent experiments. (G and K) EdCs are marked by Tg(kdrl:eGFP) expression (cyan), and myocardial cells by Tg(myl7:BFP-CAAX) expression (magenta). # indicates illustrative vectorized cartoons of the valves. (H), (J), and (L) Fisher’s exact test. AV, atrioventricular; V, ventricle; A, atrium; OFT, OFT; DBD, DNA binding domain; EdC, EdC. Scale bars, 400 μm [(E) and (F)] and 20 μm [(G) and (K)].