Dre recombinase, like Cre, is a highly efficient site-specific recombinase in E-coli, mammalian cells and mice

Tyrosine site-specific recombinases (SSRs) including Cre and FLP are essential tools for DNA and genome engineering. Cre has long been recognized as the best SSR for genome engineering, particularly in mice. Obtaining another SSR that is as good as Cre will be a valuable addition to the genomic toolbox. To this end, we have developed and validated reagents for the Dre-rox system. These include an Escherichia coli-inducible expression vector based on the temperature-sensitive pSC101 plasmid, a mammalian expression vector based on the CAGGs promoter, a rox-lacZ reporter embryonic stem (ES) cell line based on targeting at the Rosa26 locus, the accompanying Rosa26-rox reporter mouse line, and a CAGGs-Dre deleter mouse line. We also show that a Dre-progesterone receptor shows good ligand-responsive induction properties. Furthermore, we show that there is no crossover recombination between Cre-rox or Dre-loxP. Hence, we add another set of efficient tools to the genomic toolbox, which will enable the development of more sophisticated mouse models for the analysis of gene function and disease.