Systematic comparison of constitutive promoters and the doxycycline-inducible promoter

Abstract

Constitutive promoters are used routinely to drive ectopic gene expression. Here, we carried out a systematic comparison of eight commonly used constitutive promoters (SV40, CMV, UBC, EF1A, PGK and CAGG for mammalian systems, and COPIA and ACT5C for Drosophila systems). We also included in the comparison the TRE promoter, which can be activated by the rtTA transcriptional activator in a doxycycline-inducible manner. To make our findings representative, we conducted the comparison in a variety of cell types derived from several species. We found that these promoters vary considerably from one another in their strength. Most promoters have fairly consistent strengths across different cell types, but the CMV promoter can vary considerably from cell type to cell type. At maximal induction, the TRE promoter is comparable to a strong constitutive promoter. These results should facilitate more rational choices of promoters in ectopic gene expression studies.

Figure 1. Flow cytometry measurement of GFP fluorescence in eight mammalian cell types transduced with lentiviral vectors carrying GFP reporter driven by promoters of interest.

Six mammalian constitutive promoters were tested, along with the doxycycline-inducible TRE promoter at maximal induction.

Figure 2. Flow cytometry measurement of GFP fluorescence in two Drosophila cell types transduced with lentiviral vectors carrying GFP reporter driven by promoters of interest.

Two Drosophila constitutive promoters and six mammalian constitutive promoters were tested, along with the doxycycline-inducible TRE promoter at maximal induction.

Figure 3. Induction of TRE promoter driving GFP under different doses of doxycycline.

Eight mammalian cell types and two Drosophila cell types were used in the analysis. GFP fluorescence is quantitated by flow cytometry.