Endothelial cell-specific expression of Cre recombinase in transgenic mice

Endothelial cells participate in angiogenesis, vascular homeostasis, thrombosis, inflammation and vascular wall remodeling. 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 Tie2 promoter. Total six founder 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 and tissue distribution of the Cre recombinase, the Tie2-Cre transgenic line was crossed with the mouse strain carrying the Smad4 conditional alleles (Smad4(Co/Co)) or 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. Therefore, this mouse line may serve as a valuable tool for endothelial cell lineage analyses and conditional gene ablation in endothelial cells.