Transgenic mice exhibiting inducible and spontaneous Cre activities driven by a bovine keratin 5 promoter that can be used for the conditional analysis of basal epithelial cells in multiple organs

BACKGROUND: Cre/loxP-mediated genetic modification is the most widely used conditional genetic approach used in the mouse. Engineered Cre and the mutated ligand-binding domain of estrogen receptor fusion recombinase (CreER(T)) allow temporal control of Cre activity. RESULTS: In this study, we have generated two distinct transgenic mouse lines expressing CreER(T), which show 4-hydroxytamoxifen (4-OHT)-inducible and spontaneous (4-OHT-independent) Cre activities, referred to Tg(BK5-CreER(T))I and Tg(BK5-CreER(T))S, respectively. The transgenic construct is driven by the bovine Keratin 5 promoter, which is active in the basal epithelial lineage of stratified and pseudo-stratified epithelium across multiple organs. Despite the difference in 4-OHT dependency, the Tg(BK5-CreER(T))I and Tg(BK5-CreER(T))S mouse lines shared similar Cre-mediated recombination among various organs, except for unique mammary epithelial Cre activity in Tg(BK5-CreER(T))S females. CONCLUSION: These two new transgenic mouse lines for the analysis of basal epithelial function and for the genetic modification have been created allowing the identification of these cell lineages and analysis of their differentiation during embryogenesis, during perinatal development and in adult mice.