The spatiotemporal patterns of VGLL4-GFP fusion protein expression.

(A-F) Heart sections from E12.5, E13.5, E14.5, E17.5, P0 and 8 weeks were performed immunofluorescence staining with GFP (Green), endothelial maker VE-cadherin (red) and DAPI (blue). (A) VGLL4-GFP fusion protein is seldom detected in cushion mesenchyme and endothelial cells at E12.5 (white arrows). (B) VGLL4-GFP begins to be expressed in the aortic valve (AoV) and pulmonary valves (PV) at E13.5. (C) VGLL4-GFP is intensively expressed in VICs and VECs on the valve region and ventricular endothelial cells at E14.5. (D) VGLL4-GFP expression remains intensively in the valve region, and GFP signal is decreased in the ventricularis side in the aortic valve at E17.5. (E) VGLL4-GFP expression is predominately found in VICs, while in VEC and ventricularis side, GFP signal is decreased in both aortic valves and pulmonary valves at neonatal stage. (F) At adult stage (8-week-old), VGLL4-GFP expression remains intensively in valve ventricularis side and seldom detected in VECs (white arrows). I, inferior cushion; S, superior cushion; OFT, outflow tract; LV, left ventricle; RV, right ventricle; IVS, intraventricular septum; V, ventricularis; F, fibrosa; Scale Bar = 200μm.