[Establishment of keratinocyte-specific Cre recombinase transgenic mice]

A keratinocyte-specific Cre transgenic construct (pK5-Cre) containing the keratin 5 promoter, Cre recombinase gene and polyA of human growth hormone gene was generated. The 4.2 kb DNA fragment of K5-Cre-hGH was introduced into 720 fertilized zygotes by microinjection. 695 injected eggs were implanted into the oviduct of 29 female mice respectively, from which 48 off-spring were obtained. Twelve mice carrying the transgene were identified by genotyping, and the integration efficiency is 25%. The K5-Cre transgenic mice were crossed with Smad4 conditional gene targeting mice to check the tissue-specific expression of the Cre recombinase and the Cre mediated recombination in multiple tissues. The results showed that the Cre recombinase was expressed in skin tissue only and successfully mediated the recombination between the loxP sites in vivo.