Defb41, a beta-defensin gene, is expressed in the epididymis. It plays a crucial role in sperm maturation and is likely involved in the antimicrobial protection of sperm and urogenital tract epithelia [2]. Its expression is regulated by androgens. Genetic mouse models are valuable for studying its function.

In a Defb41 gene knockout study, homozygous Defb41(iCre/iCre) knock-in mice lacking Defb41 expression showed sperm with a defect in motility. The flagella of their sperm primarily bent in the pro-hook conformation, reducing straight-line motility and weakening binding to the oocyte, indicating its requirement for proper sperm maturation [1]. Also, the Defb41(iCre/wt) was used in a conditional knockout of Dicer1 in the proximal epididymis, revealing its role in segment-specific gene regulation and epithelial cell differentiation in the epididymis [3].

In conclusion, Defb41 is essential for sperm maturation, affecting sperm motility and oocyte binding. Mouse models with Defb41 gene knockout or used in conditional knockout of related genes have provided insights into its role in sperm-related functions and epididymal epithelial cell differentiation, which may have implications for understanding male reproductive health [1,3].

References:

1. Björkgren, Ida, Alvarez, Luis, Blank, Nelli, Wachten, Dagmar, Sipilä, Petra. 2016. Targeted inactivation of the mouse epididymal beta-defensin 41 alters sperm flagellar beat pattern and zona pellucida binding. In Molecular and cellular endocrinology, 427, 143-54. doi:10.1016/j.mce.2016.03.013. https://pubmed.ncbi.nlm.nih.gov/26987518/

2. Jalkanen, Jenni, Huhtaniemi, Ilpo, Poutanen, Matti. . Discovery and characterization of new epididymis-specific beta-defensins in mice. In Biochimica et biophysica acta, 1730, 22-30. doi:. https://pubmed.ncbi.nlm.nih.gov/16023745/

3. Björkgren, Ida, Saastamoinen, Lauri, Krutskikh, Anton, Poutanen, Matti, Sipilä, Petra. 2012. Dicer1 ablation in the mouse epididymis causes dedifferentiation of the epithelium and imbalance in sex steroid signaling. In PloS one, 7, e38457. doi:10.1371/journal.pone.0038457. https://pubmed.ncbi.nlm.nih.gov/22701646/