TARGETING GENE-EXPRESSION TO THE VASCULAR WALL IN TRANSGENIC MICE USING THE MURINE PREPROENDOTHELIN-1 PROMOTER

To develop a system for overexpressing genes in the vascular wall, we created transgenic mice using the reporter gene luciferase and the mur ine preproendothelin-1 promoter. In vitro analysis suggested that the murine 5'-flanking region contained endothelial-specific elements in a 5.9-kb fragment. Five transgenic mice colonies established from indep endent founders all exhibited the highest level of luciferase activity in the aorta with up to 8,540 light units per microgram of protein. I mmunohistochemistry with anti-luciferase antisera revealed high levels of expression in the endothelial cells of both large and small arteri es and lower levels of expression in veins and capillaries. Significan t expression was also seen in arterial smooth muscle cells and in sele ct epithelial surfaces which is consistent with the known distribution of endothelin-1 in mammals. To further demonstrate the targeting capa bility of this system, we overexpressed the lipid-peroxidating enzyme, human 15-lipoxygenase, in the vessel wall of transgenic mice. As with luciferase, expression of active enzyme and immunohistochemical local ization in vascular cells were documented in transgenic animals. Hence , this new system can be used to direct expression of molecules to the vascular wall for the purpose of examining the biological significanc e of either overexpression or inhibition of select proteins.