SH2 domain protein E (SHE) and ABL signaling regulate blood vessel size

Abstract

AbstractBlood vessels in different vascular beds vary in lumen diameter, which is essential for their function and fluid flow along the vascular network. Molecular mechanisms involved in the formation of a vascular lumen of appropriate size, or tubulogenesis, are still only partially understood.Src homology 2 domain containing E (She)protein was previously identified in a screen for proteins that interact with Abelson (Abl)-kinase. However, its biological role has remained unknown. Here we demonstrate that She and Abl signaling regulate vascular lumen size in zebrafish embryos and human endothelial cell culture. Zebrafishshemutants displayed increased endothelial cell number and enlarged lumen size of the dorsal aorta (DA) and defects in blood flow. Vascular endothelial specific overexpression ofsheresulted in a reduced diameter of the DA lumen, which correlated with the reduced arterial cell number and lower endothelial cell proliferation. Chemical inhibition of Abl signaling in zebrafish embryos caused a similar reduction in the DA diameter and alleviated theshemutant phenotype, suggesting that She acts as a negative regulator of Abl signaling. Enlargement of the DA lumen inshemutants correlated with an increased endothelial expression ofclaudin 5aand5b (cldn5a / cldn5b), which encode proteins enriched in tight junctions. Inhibition ofcldn5aexpression partially rescued the enlarged DA inshemutants, suggesting that She regulates DA lumen size, in part, by promotingcldn5aexpression. SHE knockdown in human endothelial umbilical vein cells resulted in a similar increase in the diameter of vascular tubes, and also increased phosphorylation of a known ABL downstream effector CRKL. These results argue that SHE functions as an evolutionarily conserved inhibitor of ABL signaling and regulates lumen size during vascular tubulogenesis.