(237) Unraveling the Role of Epithelial Androgen Receptor Signaling in Efferent Duct Development and Function

The androgen receptor (AR) signaling is crucial for the development and function of male reproductive tract organs. During embryogenesis, AR expression first appears in the epithelium of the mesonephric tubule, the precursor to the efferent duct. Efferent ducts connect the rete testis with the epididymis, serving not only as conduits for sperm transport but also as centers for fluid reabsorption. The fluid reabsorption within the efferent duct prevents testicular fluid accumulation, increases sperm concentration, and facilitates sperm maturation. Despite their critical role, it is still largely unknown how AR signaling coordinates the function and differentiation of efferent ducts from mesonephric tubules. To address this knowledge gap, we used Vil1-Cre to selectively ablate Ar in the efferent duct epithelium. The cross of Vil1-Cre with a reporter line revealed its specific Cre activity in the efferent duct epithelium from birth before major differentiation. When Vil-Cre was used to delete Ar in the efferent duct epithelium, the testes, efferent ducts, and epididymides showed normal gross morphologies. However, our closer histological analysis revealed excessive fluid buildup and dilation in the rete testis and seminiferous tubules, which is the typical outcome of efferent duct dysfunctions in fluid reabsorption. Fluid reabsorption in the efferent duct requires the coordination of two major epithelial cell types: multi-ciliated cells, which use motile cilia to stir and keep sperm in suspension, and non-ciliated cells (i.e. absorptive cells), which actively engage in testicular fluid reabsorption. Both cell types express AR, suggesting that the fluid accumulation in the testis can result from two different mechanisms: (1) occlusion by sperm aggregation due to the inhibition of multi-ciliated cell activity, and 2) reduced fluid reabsorption due to impaired absorptive cells. We are currently dissecting the cell-type-specific function of AR in causing this phenotype. Future investigations will focus on the distinct roles of AR in the multi-ciliated and absorptive cells within the efferent duct. Additionally, we plan to identify AR-target genes and regulatory transcriptional programs in efferent duct epithelium by performing RNA-seq and CUT&RUN. Taken together, our studies will promote our understanding of how AR signaling orchestrates efferent duct development and function, ultimately advancing knowledge in the endocrine regulation of male reproduction.