Fig. 5

Loss of Cadherin-5 or Yap1 prevents endocardial cell number increases during atrial chamber expansion. a–i Reconstructions of confocal z-stacks of zebrafish hearts at 52 hpf expressing the endocardial reporter Tg(kdrl:EGFP)^s843 or Tg(fli1a:nEGFP)^y7 (green) and immunolabeling against the myocardial marker Alcam (magenta). j Quantifications of endocardial cell numbers at 52 hpf. b, j Upon Wnt8a overexpression (n = 7 hearts), atrial endocardial cell numbers increase. c, j Similarly, in nkx2.5^vu179 mutants (n = 27 hearts), endocardial cell numbers increase within the atrium. d, j MO-mediated knock down of Cadherin-5 (Cdh5) (n = 7 hearts) does not cause a reduction of endocardial cell numbers within the atrium. e, j Loss of Cdh5 prevents increased atrial endocardial cell numbers upon overexpression of Wnt8a (n = 8 hearts). f, j Loss of Cdh5 suppresses increased atrial endocardial cell numbers in nkx2.5^vu179 mutants (n = 19 hearts). g, j Loss of Yap1 via MO-mediated knock down (n = 14 hearts) or in yap1^fu48 mutants (j, k) does not affect ventricular or atrial endocardial cell numbers. h, j Knock down of Yap1 in Wnt8a overexpressing embryos normalizes ventricular and atrial endocardial cell numbers (n = 8 hearts). i, j Loss of Yap1 rescues atrial endocardial cell numbers in nkx2.5^vu179 mutants (n = 17 hearts). j A loss of Nkx2.5/Nkx2.7 in yap1^fu48 mutants also rescues atrial endocardial cell numbers. A atrium, V ventricle. Scale bars, 30 μm. j, k Quantifications of endocardial cell numbers in atrium and ventricle. Mean values ± SD are shown. Two-way ANOVA was used to compare each condition with its WT control in each individual chamber (ns not significant; **p < 0.01;***p < 0.001; ****p < 0.0001)