Vascular endothelium-selective gene induction by tie2 promoter/enhancer in the brain and retina of a transgenic rat

Purpose. To produce a transgenic rat harboring the Tie2 promoter/enhancer linked green fluorescence protein (GFP) gene and investigate the blood-brain barrier (BBB)- and inner blood-retinal barrier (iBRB)-selective GFP expression in the brain and retina. Methods. Transgenic rats were produced by the microinjection of mouse Tie2/GFP gene into fertilized oocytes of Wistar rats. The expression of GFP was observed in tissue slices by confocal microscopy. Results. One of the obtained transgenic lines showed intense GFP expression in vascular endothelial cells throughout the brain. After double immunostaining with glucose transporter 1, the GFP was found to be localized in the cytoplasmic compartment of brain capillary endothelial cells. In contrast, no fluorescence was observed in neural cells. In the retina of transgenic rats, intense GFP expression was detected in retinal capillary endothelial cells. No fluorescence was detected in other cells. In kidney and liver, GFP expression was detected in vascular endothelial cells, whereas the expressed region was limited. Conclusions. Mouse Tie2 promoter/enhancer has the ability to induce gene expression selectively in vascular endothelial cells in the brain and retina of transgenic rats.