EFFICIENT CONTROL OF GENE-EXPRESSION BY SINGLE-STEP INTEGRATION OF THE TETRACYCLINE SYSTEM IN TRANSGENIC MICE

Tetracycline-regulated gene expression in eukaryotic cell lines, plant s, and transgenic mice has become a powerful tool for the analysis of eukaryotic gene expression and function. The system consists of two pl asmids, one encoding the transactivator protein under control of a vir al cytomegalovirus promoter, and the second being the tet-operator min imal promoter driving the gene of interest. Here we show that these co ntrol elements, when integrated in cis on a single plasmid, allow effi cient and tight control of reporter gene expression in vitro and in vi vo. Dependent on the route of administration of tetracycline, gene exp ression can be partially or fully repressed in transgenic mice, wherea s removal of the antibiotic induces the reporter gene in various tissu es to levels up to 800-fold more than the two-plasmid system. In addit ion, crossing and analysis of animals transgenic for the individual co mponents of the system are unnecessary, and genetic segregation of the control elements during breeding is prevented.