Transcriptomic Effects of Tet-on and Mifepristone Inducible Systems in Mouse Liver

Abstract

Control of transgene expression from long-term expression vectors can be achieved with inducible and regulated promoters. The two most commonly used inducible systems employ doxycycline or mifepristone as the drug activating a silent trans-activator, which is expressed from a constitutive promoter. We evaluated the alterations provoked by constitutive expression in the liver of rtTA2 S -M2 (rtTA2; second-generation reverse tetracycline-controlled trans-activator) and GLp65, which are the trans-activators of the doxycyline-and mifepristone-inducible systems, respectively. To this end we performed transcriptomic analysis of mice expressing these trans-activators in the liver over 1 month. rtTA2 expression induced alterations in a few genes (69 gene probesets; false discovery rate [FDR], ϳ0.05), whereas GLp65 caused more numerous changes (1059 gene probe-sets, an FDR of ϳ0.05). However, only 20 and 53 of the genes from the rtTA2 and GLp65 groups, respectively, showed changes (R-fold Ն 3). Functional assignments indicate that alterations were mild and of little general significance. Few additional transcriptomic changes were observed when expressing trans-activators in the presence of inducer drugs; most were due to the drugs themselves. These results and the absence of toxicity observed in treated animals indicate that the two inducible systems are well tolerated and have little impact on the liver transcriptome profile. The milder alterations found with the use of rtTA2 suggest that this system is possibly safer for gene therapy applications. 1233

Porphobilinogen deaminase over-expression in hepatocytes, but not in erythrocytes, prevents accumulation of toxic porphyrin precursors in a mouse model of acute intermittent porphyria

“…A previous report [20] showed that the HD-based procedure allowed for a sustained protein expression over at least 50 days in mice receiving a plasmid containing the human a-1-antitrypsin gene controlled by the same promoter used in this study [18]. In addition, experiments performed by our group showed that DNA transfected into mouse liver by HD injection can be transferred and expressed in about 10-15% of hepatocytes (Reboredo M, unpublished data).…”

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Establishment of novel embryonic stem (ES) cell lines from OG2/rtTA blastocysts

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