Lactoferrin-iCre: a new mouse line to study uterine epithelial gene function.

Transgenic animal models are valuable for studying gene function in various tissue compartments. Mice with conditional deletion of genes in the uterus using the Cre-loxP system serve as powerful tools to study uterine biology. The uterus is comprised of 3 major tissue types: myometrium, stroma, and epithelium. Proliferation and differentiation in each uterine cell type are differentially regulated by ovarian hormones, resulting in spatiotemporal control of gene expression. Therefore, examining gene function in each uterine tissue type will provide more meaningful information regarding uterine biology during pregnancy and disease states. Although currently available Cre mouse lines have been very useful in exploring functions of specific genes in uterine biology, overlapping expression of these Cre lines in more than 1 tissue type and in other reproductive organs sometimes makes interpretation of results difficult. In this article, we report the generation of a new iCre knock-in mouse line, in which iCre is expressed from endogenous lactoferrin (Ltf) promoter. Ltf-iCre mice primarily direct recombination in the uterine epithelium in adult females and in immature females after estrogen treatment. These mice will allow for specific interrogation of gene function in the mature uterine epithelium, providing a helpful tool to uncover important aspects of uterine biology.