Inducible Cre Mice
The Cre/lox site-specific recombination system has emerged as an important tool for the generation of conditional somatic mouse mutants. This method allows one to control gene activity in space and time in almost any tissue of the mouse, thus opening new avenues for studying gene function and for establishing sophisticated animal models of human diseases. A major technical advance in terms of in vivo inducibility was the development of ligand-dependent Cre recombinases that can be activated by administration of tamoxifen to the animal. Here we describe how tamoxifen-dependent Cre recombinases, so-called CreER recombinases, work and how they can be used to generate time- and tissue-specific mouse mutants. The focus will be on the CreERT2 recombinase, which is currently the most successful CreER version. We will give an overview of available CreERT2 transgenic mouse lines and present protocols that detail the generation of experimental mice for inducible gene knockout studies, the induction of recombination by tamoxifen treatment, and the analysis of the quality and quantity of recombination by reporter gene and target gene studies. Most of the protocols can also be used as general guidelines for the generation and characterization of Cre/lox-mediated genome modifications in mice.
Key wordsTransgenic mice inducible gene knockout somatic mutagenesis CreER recombinase tamoxifen in utero ROSA26 R26R X-Gal staining mouse models of human disease
We thank the members of the Feil laboratory for critical discussion. Work in the authors’ laboratory was supported by grants from the VolkswagenStiftung and the Deutsche Forschungsgemeinschaft.
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