TETRACYCLINE-CONTROLLED GENE-EXPRESSION SYSTEM ACHIEVES HIGH-LEVEL AND QUANTITATIVE CONTROL OF GENE-EXPRESSION

The tetracycline-controlled gene expression system utilizes the contro l elements of the tetracycline resistance operon encoded in Tn10 of Es cherichia coli to control gene expression in eukaryotic cells. Here we demonstrate the quantitative control of the expression of the lucifer ase gene, dihydrofolate reductase gene, and bcl-2 gene in HeLa S3 or C hinese hamster ovary AA8 cells using the tetracycline-controlled gene expression system. Regardless of the host cell lines or the genes bein g expressed, there is a common range of tetracycline concentration wit hin which the expression of genes is most sensitively regulated. In ad dition, the maximal gene expression level of the tetracycline-controll ed gene expression system is higher than that of the wild-type CMV pro moter/enhancer-driven system. Nonetheless, careful selection of stably transfected clones is necessary to achieve the optimally regulated ge ne expression using this system. (C) 1996 Academic Press, Inc.