ANDROGENS REGULATE THE SECRETION OF PROSAPOSIN IN RAT EPIDIDYMIS

CARVELLI, LORENA; ZYLA, LEILA; MORALES, CARLOS; SOSA ESCUDERO, MIGUEL ÁNGEL

Quebec

Encuentro; BREAKTRHOUGHS IN REPRODUCTION AND DEVELOMPMENT; 2013

Mammalian spermatozoa become functionally mature as they pass through the epididymis, acquiring the ability to move forward, undergo acrosome reaction, bind to and penetrate the oocyte vestments and attain syngamy. The newly formed spermatozoa are surrounded by plasma membranes that are modified during epididymal maturation. The remodelling process includes the uptake of epididymal glycoproteins and modification of lipid composition. Recently, we demonstrated that prosaposin (PSAP), the precursor of saposins A-D, is secreted by the epididymal epithelium. In addition, immunofluorescence and flow cytometry indicate that the enzyme Arylsulphatase A (ARSA) and PSAP are present on the heads of caudal epididymal sperm. This observation suggests that acquisition of ARSA and PSAP increase during epididymal transit. ARSA modifies sulphatide, a process that requires prosaposin (PSAP) or its derived saposin B. The major sulfoglycolipid of the sperm plasmalemma is a sulfogalactosylglycerolipid (SGG), suspected to be a substrate of ARSA/PSAP. Based on these findings and considering the androgen dependence of the epididymis, we examined the regulation of PSAP secretion in epididymal fluids. To this effect we used control and castrated rats followed or not by testosterone replacement. Samples were analyzed by electrophoresis and immunoblotting under reducing or non-reducing conditions. We observed the presence of PSAP oligomers (250 kDa) in the epididymal fluids of the three regions, demonstrated that castration decreases monomeric PSAP (70 kDa) and increases oligomeric PSAP. These effects were reversed by testosterone replacement, indicating that androgens regulate the secretion of PSAP in the epididymal epithelium.