Tetracycline-controlled transcriptional regulation systems: countermeasures to eliminate basal transgene leaks in Tet-based systems

摘要

To analyze the function of any given transgene( s) accurately in transgenic mice, and to produce credible transgenic animal models of various human diseases (precisely and realistically mimicking disease states), it is critical to be able to control gene expression in the animals conditionally. The ability to switch gene expression "on" or "off" in the restricted cells or tissue(s) at specific time(s) allows unprecedented flexibility for exploring gene function(s) in both the health and the disease. Pioneering work on inducible transgene expression has led to the development of a wide variety of controlled gene expression systems that meet this criterion. Among them, the tetracycline-inducible systems (e.g. Tet-off and Tet-on) have been widely, frequently and successfully employed in vitro and in vivo. These systems, however, are not always tight but leaky; sometimes the leakage is significant. In some circumstances, the resulting leak is acceptable, but in others, it is more problematic. Though these systems face this disadvantage, i. e. basal transgene leakage in vitro and in vivo, several approaches, including using improved versions (e.g. rtTA2~s -M2 and rtTA2~S -S2) of rtTA, tetracycline-controlled transcriptional silencer (tTS), an "ideal" minimal promoter in responsive components or combinations thereof, have been developed to avoid this limitation effectively. In this review we discuss the countermeasures available to eliminate basal transgene leakage from Tet-based systems.