Spatio-temporally controlled site-specific somatic mutagenesis in the mouse

Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14559-63. doi: 10.1073/pnas.94.26.14559.


The efficient introduction of somatic mutations in a given gene, at a given time, in a specific cell type will facilitate studies of gene function and the generation of animal models for human diseases. We have shown previously that conditional recombination-excision between two loxP sites can be achieved in mice by using the Cre recombinase fused to a mutated ligand binding domain of the human estrogen receptor (Cre-ERT), which binds tamoxifen but not estrogens. DNA excision was induced in a number of tissues after administration of tamoxifen to transgenic mice expressing Cre-ERT under the control of the cytomegalovirus promoter. However, the efficiency of excision varied between tissues, and the highest level ( approximately 40%) was obtained in the skin. To determine the efficiency of excision mediated by Cre-ERT in a given cell type, we have now crossed Cre-ERT-expressing mice with reporter mice in which expression of Escherichia coli beta-galactosidase can be induced through Cre-mediated recombination. The efficiency and kinetics of this recombination were analyzed at the cellular level in the epidermis of 6- to 8-week-old double transgenic mice. We show that site-specific excision occurred within a few days of tamoxifen treatment in essentially all epidermis cells expressing Cre-ERT. These results indicate that cell-specific expression of Cre-ERT in transgenic mice can be used for efficient tamoxifen-dependent, Cre-mediated recombination at loci containing loxP sites to generate site-specific somatic mutations in a spatio-temporally controlled manner.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Epidermis / metabolism
  • Gene Targeting
  • Humans
  • Integrases / genetics*
  • Mice
  • Mice, Transgenic
  • Mutagenesis, Site-Directed*
  • Receptors, Estrogen / genetics*
  • Receptors, Estrogen / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Recombination, Genetic
  • Tamoxifen / metabolism
  • Viral Proteins*


  • Receptors, Estrogen
  • Recombinant Fusion Proteins
  • Viral Proteins
  • Tamoxifen
  • Cre recombinase
  • Integrases