Hemizygous transgenic mice are viable, fertile, normal in size, and do not display any gross physical or behavioral abnormalities. These transgenic mice harbor co-injected transgenic constructs. The reverse tetracycline-controlled transactivator (rtTA) protein is expressed under the direction of the endothelial-specific receptor tyrosine kinase enhancer/promoter (Tek). The second transgenic construct expresses a nuclear-localizing beta-galactosidase gene (lacZ) under the control of a tetracycline-responsive element (TRE). In the presence of tetracycline or a tetracycline analog (such as doxycycline), selective expression of lacZ is observed in the nuclei of vascular endothelium in a wide variety of tissues (aorta, heart, brain, lung, kidney, liver, spleen, uterus, prostate, stomach, skeletal muscle, large and small intestine). Expression is observed as early as embryonic day 9.5. In the absence of tetracycline, some lacZ expression occurs in the smaller branches of the aorta. Additionally, the donating investigators report a trend towards diminished lacZ expression when the alleles are crossed onto a C57BL/6 background. This strain provides a tool that allows the inducible expression of genes in the vascular endothelium during early developmental stages and in the adult.
This strain is on a genetic background different from that on which the allele was first characterized. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
