Construction of a targeting vector by recombineering and generation of Cebpd conditional knockout mice for the study of cell-type specific functions of C/EBPdelta in vivo

The Cebpd gene encodes the transcription factor C/EBPdelta. A germ line deletion of the Cebpd gene in mice increased tumor multiplicity but reduced metastatic progression in a transgenic model of mammary tumorigenesis, indicating that C/EBPdelta can be both a tumor suppressor and tumor promoter. To address whether these phenotypes were caused by C/EBPdelta functions in mammary epithelial cells and/or cells of the tumor microenvironment, we needed a conditional knockout (cko) mouse model where the Cebpd gene can be deleted by cell-type specific expression of a Cre recombinase transgene. I have used homologous recombination technology to construct a cko targeting vector in which Cre recombination sites were placed on either side of the Cebpd coding region. This vector was used to generate mice carrying a Cebpd cko allele, and that can now be crossed into various mouse models to study cell-type specific deletions of Cebpd..