Temporally-controlled site-specific mutagenesis in the basal layer of the epidermis: comparison of the recombinase activity of the tamoxifen-inducible Cre-ERT and Cre-ERT2 recombinases

• Published in: Nucleic acids research 1999-11, Vol.27 (22), p.4324-4327
• Main Authors: Indra, Arup Kumar, Warot, Xavier, Brocard, Jacques, Bornert, Jean-Marc, Xiao, Jia-Hao, Chambon, Pierre, Metzger, Daniel
• Format: Article
• Language: English
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/27.22.4324

Conditional DNA excision between two LoxP sites can be achieved in the mouse using Cre-ERT, a fusion protein between a mutated ligand binding domain of the human estrogen receptor (ER) and the Cre recombinase, the activity of which can be induced by 4-hydroxy-tamoxifen (OHT), but not natural ER ligands. We have recently characterized a new ligand-dependent recombinase, Cre-ERT2, which was ∼4-fold more efficiently induced by OHT than Cre-ERT in cultured cells. In order to compare the in vivo efficiency of these two ligand-inducible recombinases to generate temporally-controlled somatic mutations, we have engineered transgenic mice expressing a LoxP-flanked (floxed) transgene reporter and either Cre-ERT or Cre-ERT2 under the control of the bovine keratin 5 promoter that is specifically active in the epidermis basal cell layer. No background recombinase activity could be detected, while recombination was induced in basal keratinocytes upon OHT administration. Interestingly, a dose-response study showed that Cre-ERT2 was ∼10-fold more sensitive to OHT induction than Cre-ERT.