Temporally Controlled Site-Specific Mutagenesis in the Germ Cell Lineage of the Mouse Testis

We have obtained a PrP-Cre-ERT transgenic mouse line (28.8) that selectively expresses in testis the tamoxifen-inducible Cre-ERT recombinase under the control of a mouse Prion protein (PrP) promoter-containing genomic fragment. Cre-ERT is expressed in spermatogonia and spermatocytes, but not in Sertoli and Leydig cells. We also established reporter PrP-L-EGFP-L transgenic mice harboring a LoxP-flanked enhanced green fluorescent protein (EGFP) Cre reporter cassette under the control of the same PrP promoter-containing genomic fragment that exhibits prominent EGFP expression in brain and testis. Using the PrP-L-EGFP-L as well as other Cre-reporter mice, we demonstrate that tamoxifen administration efficiently and selectively induces Cre-mediated recombination in the germ cell lineage. The established PrP-Cre-ERT line should provide a valuable tool for studying functions of germ cell-expressed genes involved in spermatogenesis.