Keratinocyte-specific knockout mice models via Cre–loxP recombination system

The Cre recombinase/loxP (Cre/loxP) system has emerged as a useful tool in genetic manipulations. Generally, any DNA sequence of interest can be deleted when flanked with loxP sites. The conditional (timely or spatially controlled) expression of Cre recombinase enables to determine, where (e.g. in which cell type or tissue) and when (at which time of life or of developmental stage of cells/tissues) the deletion of the floxed DNA sequence should occur. Therefore, two mouse lines are usually needed for conditional site-specific genome modification. This review aims to provide a general overview of the Cre/loxP system, elaborate on the different keratinocyte specific knockout mice used to study gene function in keratinocytes, and finally demonstrate the generation of a conditional knockout mice. Knockout mice have been efficient and powerful approach to understand the functions of specific genes in development and physiological homeostasis. However, deletion of the specific genes which are concerned in stages of development induces to embryonic lethality. To overcome this obstacle, Cre/loxP system has been used to delete a gene in a specific organ or tissue, or at a specific embryonic developmental stage. Conditional knockout mice have allowed extensive research of the epidermis and helped elucidate roles of many gene functions in keratinocytes.