Discovery and characterization of new epididymis-specific beta-defensins in mice.

The male urogenital tract epithelium is exposed to several pathogens, but only a few are potent enough to cause infection in a healthy individual. The exact mechanisms that protect the male reproductive tract from ascending pathogenic micro-organisms are still poorly characterized. We recently reported a method to identify novel epididymis-specific genes by analyzing the expressed sequence tags (ESTs) present in the mouse epididymal cDNA library of the UniGene collection at National Center for Biotechnology Information (NCBI). In the present study, we discovered in silico two novel epididymal genes: the beta-defensins Defb41 and Defb42. The full-length cDNAs for the genes were acquired by the RT-PCR and 5'-RACE approaches and were subsequently sequenced. Q-RT-PCR and in situ hybridization revealed Defb41 and Defb42 to be expressed mainly in the proximal caput. The expression of both defensins was found to be regulated by androgens. Based on their structure and expression pattern, Defb41 and Defb42 are suggested to have a role in the antimicrobial protection of sperm and urogenital tract epithelia.