Epididymal initial segment-specific Cre recombinase activity in Lcn8-Cre knock-in mice

Background Sperm acquire the ability to fertilize ova through a complex process of epididymal maturation. To identify the functions of genes expressed in the proximal epididymis, mouse models specific to this region are needed. Methods and results A Lcn8-Cre knock-in mouse line was generated using CRISPR/Cas9 technology. A 37 bp coding sequence of Lcn8 from the ATG start codon was replaced by an NLS-Cre-polyA cassette, resulting in Cre expression and the absence of Lcn8. Epididymal initial segment-specific Cre expression was identified using RT-PCR and western blotting, and the spatial–temporal Cre activity was further confirmed by using the Rosa26 tdTomato reporter mice. Immunofluorescence staining showed that active Cre recombinase was present in the principal cells. Histological analyses of sperm and epididymides, and the four-month mating tests, were used to confirm that Cre expression did not affect normal development and male fecundity. Conclusions The novel Lcn8-Cre mice can be used to establish epididymal initial segment-specific conditional knock-out mouse models.