Temporal control of gene expression in transgenic mice by a tetracycline-responsive promoter.

TLDR

Temporal promoters enable controlled gene function studies in transgenic animals. The study evaluates a tetracycline‑responsive system for temporally controlling gene expression in mice. A tTA protein activates a minimal promoter with tet operators in the absence of tetracycline, and transgenic mice were engineered to carry either reporter genes under this promoter or tTA under an hCMV IE1 promoter. tTA presence induced reporter expression up to several thousand‑fold, but tetracycline suppressed it, demonstrating reversible, temporally controlled transgene expression useful for gain‑of‑function studies.

Abstract

Promoters whose temporal activity can be directly manipulated in transgenic animals provide a tool for the study of gene functions in vivo. We have evaluated a tetracycline-responsive binary system for its ability to temporally control gene expression in transgenic mice. In this system, a tetracycline-controlled trans-activator protein (tTA), composed of the repressor of the tetracycline-resistance operon (tet from Escherichia coli transposon Tn10) and the activating domain of viral protein VP16 of herpes simplex virus, induces transcription from a minimal promoter (PhCMV*-1; see below) fused to seven tet operator sequences in the absence of tetracycline but not in its presence. Transgenic mice were generated that carried either a luciferase or a beta-galactosidase reporter gene under the control of PhCMV*-1 or a transgene containing the tTA coding sequence under the control of the human cytomegalovirus immediate early gene 1 (hCMV IE1) promoter/enhancer. Whereas little luciferase or beta-galactosidase activity was observed in tissues of mice carrying only the reporter genes, the presence of tTA in double-transgenic mice induced expression of the reporter genes up to several thousand-fold. This induction was abrogated to basal levels upon administration of tetracycline. These findings can be used, for example, to design dominant gain-of-function experiments in which temporal control of transgene expression is required.