Fig. 4

Notch signaling reporter expression is observed in cardiomyocytes in the absence of ErbB2 signaling in rbx1 mutants

(A-D′) Confocal images of 104 hpf Tg(tp1:VenusPEST); Tg(kdrl:Hsa.HRAS-mCherry) hearts in 2D mid-sagittal views (A–D), and 3D maximum intensity projections (A′-D′). (A-B′) Notch reporter expression after DMSO treatment in rbx1^+/+ (A-A′) and rbx1^−/− (B–B′) larvae indicated with arrows. (C-D′) Notch reporter expression after ErbB2 inhibitor treatment in rbx1^+/+ (C–C′) and rbx1^−/− (D-D′, arrows) larvae. rbx1^+/+ larvae do not exhibit Notch reporter expression in their ventricular myocardium in the absence of ErbB2 signaling (C–C′), while Notch reporter expression is observed in the ventricular myocardium in rbx1^−/− (D-D′, arrows) larvae even in the absence of ErbB2 signaling. (E-H′) Confocal images of 104 hpf Tg(tp1:VenusPEST); Tg(myl7:MKATE-CAAX) hearts in 2D sagittal views (E–H) and 3D maximum intensity projections (E′-H′). (E-F′) Notch reporter expression after DMSO treatment in rbx1^+/+ (E-E′) and rbx1^−/− (F–F′) larvae is indicated with white arrows. (G-H′) Notch reporter expression in the absence of ErbB2 signaling is only observed in the ventricular myocardium in rbx1^−/− larvae (H–H′ arrow). (I) Quantification of Notch positive CMs in 104 hpf rbx1^+/+ and rbx1^−/− ventricles treated with DMSO or ErbB2 inhibitor. Each dot represents one heart. Data are shown as mean ​± ​SEM. P-values calculated by Student's t-test. V: ventricle, A: atrium; scale bars, 50 ​μm.