Regulation of Aortic Morphogenesis and VE-Cadherin Dynamics by VEGF

In amniote vertebrates, the definitive dorsal aorta is formed by the side-to-side fusion of two primordial aortic endothelial tubes. Formation of the definitive dorsal aorta requires extensive cellular migrations and rearrangements of the primordial tubes in order to generate a single fused vessel located at the embryonic ventral midline. This study examines the role of VEGF signaling in the generation of the definitive dorsal aorta. Through gain- and loss-of-function studies in vivo in the chick embryo, we document a requirement for VEGF signaling in growth and migration of the paired primordia, and identify a developmental window in which aorta development is particularly sensitive to VEGF signaling. We also find that VEGF signaling regulates the intracellular distribution between membrane and cytoplasm of the cell-cell adhesion molecule VE-Cadherin in aortic endothelial cells in vivo, suggesting a possible mechanism for how VEGF regulates aortic endothelial cell dynamics during the fusion process.