Regulation of transgene expression using tetracycline.

Transgenesis has proven useful in creating animal models that mimic certain disease states, providing a mechanistic approach for understanding the underlying disease mechanisms at the molecular and cellular levels. With traditional transgenics, the gene of interest is cloned behind a promoter that has the desired expression pattern, allowing the gene to be expressed in those tissues at the developmental times that the promoter is active. In order to more precisely control gene expression both in vitro and in vivo, inducible systems that use pharmacologic intervention to control transgene expression have been developed (UNIT 16.14). As previously described, the system consists of two components, an activator that is regulated by tetracycline and a responder that is dependent upon the activator. Both limbs of the system will be discussed in the context of inducible and reversible transgene expression that is cell type- or organ-specific, with particular attention paid to the cardiovascular system.