LOW LEVELS OF TESTOSTERONE AFFECT THE OLIGOMERIZATION AND SECRETION OF PROSAPOSIN IN RAT EPIDIDYMIS

ZYLA L; AGUILERA C; MALOSSI E; BANNOUD N; RUIZ AM; SOSA MA; CARVELLI L

San Luis

Congreso; XXX Reunión Anual de la Sociedad de Biología de Cuyo; 2012

Sociedad de Biología de Cuyo

In mammals, sperm maturation is favored by the secretory activity of the epididymal epithelium. The lumen of the organ is particularly rich in lysosomal proteins. This striking phenomenon seems to be crucial for acquiring the fertilizing capacity. Prosaposin (PSAP) is the precursor (65 kDa) of the lysosomal proteins saposins related with the sphingolipid metabolism. Previous findings show that PSAP (70 kDa) may covalently aggregate into oligomers (130-250 kDa). Moreover, these oligomers can not be recognized by the specific receptor (sortilin) and they enter in a yet unknown secretion pathway. Based on the characteristics of epididymal secretion and considering the hormonal dependence of this organ, we here evaluated the degree of oligomerization of PSAP in the rat epididymal fluid of controls, castrated or castrated followed by testosterone replacement. Samples were analyzed by electrophoresis under reducing or non-reducing conditions followed by immunoblot. We observed, for the first time, the presence of PSAP oligomers (250 kDa) in the epididymal fluid of the three regions of the organ. In turn, it was demonstrated that castration induces a decrease in secretion of monomeric PSAP (70 kDa) and an increase of the oligomeric forms along the whole duct. These effects were reversed by hormone replacement, indicating that testosterone influences on the oligomerization of PSAP, and consequently affects the secretion of this lysosomal protein in the epididymal epithelium.