Endothelial Cell-Specific Expression Of Cre Recombinase In Transgenic Mice

Endothelial cells participate in many physiological and pathological processes like angiogenesis, vascular homeostasis, thrombosis, inflammation and vascular wall remodeling. Endothelial cells play important roles in regulation of function and homeostasis of the circulatory system.To study the function of genes in endothelial cells using Cre/loxP system, we generated Tie2-Cre transgenic mice, in which expression of Cre recombinase is driven by promoter and enhancer of Tie2 gene, a molecular marker for endothelial cells. The 15.9 kb DNA fragment of Tie2-Cre transgene was introduced into 295 fertilized zygotes by microinjection. 287 injected eggs were implanted into the oviducts of 14 female mice respectively, from which 57 offspring were obtained. Six mice carrying the Tie2-Cre transgene were identified by genomic PCR and Southern blot. The integration efficiency is 11%. In order to test the excision activity of the Cre recombinase, the Tie2-Cre transgenic line was crossed with the mouse strain carrying the Smad4 conditional alleles (Smad4^Co/Co) and the reporter line ROSA26. PCR of multiple tissue DNA from Tie2-Cre; Smad4^Co/+ mice revealed the Cre activity in all tissues containing endothelial cells. We detected pan-endothelial expression of the Cre transgene in Tie2-Cre; ROSA26 double transgenic embryos by LacZ staining.All our results demonstrated that the Tie2-Cre transgenic mouse we generated in this study could serve as a valuable tool for endothelial cell lineage analyses and conditional gene ablation in endothelial cells.