Castration results in increased procathepsin D secretion mediated by prosaposin oligomers in adult rat epididymis

CARVELLI L; AGUILERA C; HERMO L; MORALES CR; ZYLA L; SOSA MA

Montreal

Conferencia; 7th International conference on the epididymis; 2018

The epididymis is implicated in sperm maturation by remodeling the sperm plasma membrane throughout lysosomal proteins secreted by the epididymal epithelium. CatD is a lysosomal hydrolase which is secreted by principal cells into the epididymal lumen, and this secretion could be associated with PSAP. PSAP is nonenzymic protein that is trafficked in a monomeric form (70kDa) to the lysosomes or secreted as oligomers (250kDa). Here, we analyzed cathepsin D (catD) and prosaposin (PSAP) expression in the cauda epididymis of intact rats and rats subjected to castration followed or not by testosterone replacement. Immunoblotting showed an increase in the expression and secretion of catD due to castration in all epididymal regions, which was reversed by testosterone injection. Immunohistochemistry showed a supranuclear localization of catD in the principal cells, and the reaction was more intense in castrated animals, consistent with the immunoblots. Co-immunoprecipitation demonstrated that secreted catD is associated in part to PSAP and this interaction increased by castration (Figure 1). From this, we analysed oligomeric status of PSAP in epididymal fluid. By immunoblotting, we observed that castration increased oligomeric PSAP (250kDa) in the fluid at the expense of monomeric form (70 kDa) (Figure 2). Like catD, PSAP showed a supranuclear staining in the principal cells that spread over the entire apical cytoplasm after castration. Our results suggest that PSAP oligomers associate to catD due to castration, inducing its secretion. In conclusion, testosterone may regulate the secretion of catD and PSAP creating an optimal environment for the sperm maturation.