Production of transgenic mice
Standard molecular techniques were used to assemble the transgenic construct, pTRE-E2. This transgene contains the tetracycline responsive hCMV*-1 promoter [consisting of the tetracycline responsive element (TRE) and a minimal hCMV promoter] [25] from pTRE2 (Clontech Inc., Mt. View, CA), a chimeric intron from pCI (Promega) to increase message stability and expression [26,27], a Kozak consensus sequence at the initiation codon to optimize translation [28], the human E2 cDNA which has been modified to contain a 4× alanine linker followed by a c-myc epitope tag at the carboxy terminus to facilitate detection, and an SV40 late polyadenylation sequence from pCI for enhanced mRNA stability and translation.
The 2.48 kb TRE-E2 transgene was purified from vector sequences following digestion with XhoI and BamHI and injected into C57BL/6J or C57BL/6J × Strain 129SvEv mouse embryos at the transgenic core facilities of the University of Pittsburgh and the University of Cincinnati, respectively. Genomic DNA from the tail of mice was screened by Southern blot analysis following digestion with EcoRI and hybridization to an ~400 bp probe derived from the SV40 portion of the TRE-E2 transgene.