A single plasmid vector (pSTAR) mediating efficient tetracycline-induced gene expression.

A plasmid vector (pSTAR) has been constructed which confers neomycin resistance for selecting stably transfected cells, possesses a cloning cassette for placing a gene of interest under the control of the tetO DNA motif, and expresses rtTAnls which, upon association with tetracycline, binds to and drives gene expression from the tetO DNA motif. The plasmid pSTAR/LacZ, which has the gene for beta-galactosidase inserted into the cloning cassette, was transfected into Chinese hamster ovary (CHO) cells and selected for stably transfected cells. In pooled transfectants of CHO, tetracycline induced the expression of beta-galactosidase in 10-30% of cells. Using clonal transfectants, beta-galactosidase expression was induced by tetracycline in essentially every cell. Furthermore, induction of beta-galactosidase expression by tetracycline was both dose- and time-dependent. Similar tetracycline-induced beta-galactosidase expression is also observed in other cell types. The pSTAR vector is thus suited to facilitate the application of tetracycline-induced gene expression in diverse research areas.