Notch4 and Jagged-1 induce microvessel differentiation of rat brain endothelial cells

The mouse Notch4 gene is expressed specifically in endothelial cells. Notch4/int-3, a truncated form of Notch4, acts as a constitutive activated Notch receptor. We used rat brain microvessel endothelial cells (RBE4) to study the role of Notch4 and Jagged-1 in endothelial cell differentiation. Both Notch4/int-3 and Jagged-1 were able to induce microvessel-like structures with morphological and biochemical properties similar to brain endothelial microvessels. Ectopic expression of full-length Notch4 did not effect RBE4 cells. Activation of the Notch signal transduction pathway was measured by the induction of endogenous Notch4 and Jagged-1 genes and of Jagged-1 proteins. The observed morphological changes to RBE4 cells correlated with endogenous Notch4 and Jagged-1 gene activation. Our observations demonstrate that Notch signaling can promote endothelial cell differentiation and morphogenesis.