Expression of tamoxifen-inducible CRE recombinase in Lcn5-CreERT2 transgenic mouse caput epididymis.

The epididymis, which connects the testis to vas deferens, plays a crucial role regulating sperm maturation and fertilization. Here, a tamoxifen-inducible CreERT2 recombinase transgenic mouse was generated to study the function of genes in the caput epididymis using the Cre/LoxP system, which is driven by the 1.8-kb Lcn5 promoter (Lcn5-CreERT2 ). Both CRE recombinase and ERT2 mRNA were specifically expressed in the caput epididymis, beginning at postnatal Day 30 and increasing thereafter. Crossing these Lcn5-CreERT2 transgenic mice with Rosa26; mT/mG reporter mice, which express membrane-bound GFP (mGFP) only after CRE is active at its genetic locus, resulted in the presence of GFP only in the middle/distal caput epididymis after tamoxifen induction. Efficiency of the CRE recombinase production in the caput epididymis was dose- and time-dependent. These tamoxifen-inducible caput epididymis-specific CRE recombinase transgenic mice thus provides a simple approach to modulate epididymal principal cells in vivo, allowing for the genetic investigation of caput epididymis-specific gene functions during sperm maturation. 84: 257-264, 2017. © 2016 Wiley Periodicals, Inc.