Interaction of lysosomal enzymes with spermatozoa from bovine epididymis. Possible implications of MPRs

AGUILERA AC; BOSCHIN V,; CARVELLI L; SOSA MA

Rosario

Congreso; L Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2014

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Mammalian epididymis participates in sperm maturation through its endocytic and secretory activity. In bulls, as in other mammals, many lysosomal enzymes (LE) are secreted to the epididymal fluid. Here, we proposed to study the interaction LE secreted by the epididymal epithelium with spermatozoa, in order to evaluate the participation of mannose-6-phosphate receptors (MPRs). We observed that beta-galactosidase (beta-Gal), beta-glucuronidase (beta-Glu), and N-acetyl-beta-D-glucosaminidase (beta-NAG) associated to sperm membrane are released easily with increasing ionic strength or M6P, meanwhile alpha-mannosidase (alpha-MAN) and alpha-fucosidase (alpha-Fuc) mostly remained associated to the gametes after treatments. The values of KD and Bmax for MPRs were estimated from curves of binding assays usingan exogenous enzyme, and showed a higher number of active CI-MPR sites and with more affinity tophosphomannosyl ligands. We also observed that both MPRs distribute differently on the sperm surface and that CDMPR is redistributed during epididymal transit. Instead, the CIMPR is mostly concentrated at the acrosomal region along the epididymal duct. We concluded that both MPRs are present in bull spermatozoa and they interactdifferently with LE in the epididymal lumen. Thus, MPRs may interact with LE for transport to the femalereproductive tract, suggesting new roles for these receptors.