Ligand-Activated Site-Specific Recombination in Mice

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 93; no. 20; pp. 10887 - 10890
• Main Authors: Feil, R., Brocard, J., Mascrez, B., LeMeur, M., Metzger, D., Chambon, P.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01-10-1996; National Acad Sciences
• Subjects: Alleles; Animals; DNA; Gene Expression Regulation; Gene targeting; Genes; Genetic Engineering - methods; Genetic mutation; human cytomegalovirus; Integrases - chemistry; Integrases - metabolism; Ligands; Messenger RNA; Mice; Mice, Transgenic; Polymerase chain reaction; Receptors, Estrogen - chemistry; Receptors, Estrogen - metabolism; Recombinant Fusion Proteins - metabolism; Recombination, Genetic; Sequence Deletion; Tamoxifen - pharmacology; Transgenes; Transgenes - genetics; Transgenic animals; Viral Proteins
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.93.20.10887

Current mouse gene targeting technology is unable to introduce somatic mutations at a chosen time and/or in a given tissue. We report here that conditional site-specific recombination can be achieved in mice using a new version of the Cre/lox system. The Cre recombinase has been fused to a mutated ligand-binding domain of the human estrogen receptor (ER) resulting in a tamoxifen-dependent Cre recombinase, Cre-ER$^{\text{T}}$, which is activated by tamoxifen, but not by estradiol. Transgenic mice were generated expressing Cre-ER$^{\text{T}}$ under the control of a cytomegalovirus promoter. We show that excision of a chromosomally integrated gene flanked by loxP sites can be induced by administration of tamoxifen to these transgenic mice, whereas no excision could be detected in untreated animals. This conditional site-specific recombination system should allow the analysis of knockout phenotypes that cannot be addressed by conventional gene targeting.