Changes in lysosomal enzymes and mannose-6-phosphate receptors related to sexual maturation in bull epididymis

AGUILERA AC; CARVELLI L; BOSCHIN V; MOHAMED F; ZYLA L; SOSA MA

REPRODUCTION FERTILITY AND DEVELOPMENT

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2015

1031-3613

Abstract. One of the most striking features of the mammalian epididymis is the secretion of lysosomal enzymes (LE).These LE may play a role in sperm maturation. In the present study we investigated the activity and distribution of four LE(b-galactosidase (b-Gal), N-acetyl-b-D-glucosaminidase (b-NAG), a-mannosidase (a-Man) and b-glucuronidase) inbull epididymis at two different ages (6 months and 4 years) to determine whether these enzymes vary with sexual5 maturity. In young, sexually immature (SI) bulls we found high LE activity in the epididymal tissue that accounts for adeveloped and active lysosomal apparatus. In contrast, low LE activity was measured in sexually mature (SM) bulls, andb-NAG and b-Gal were mostly secreted into the lumen. We also attempted to correlate LE distribution with the expressionand functionality of mannose-6-phosphate receptors (MPRs), which are thought to be involved in proper delivery of LE tolysosomes. The cation-dependent MPR was highly expressed in SI bulls, with expression decreasing during adulthood,10 whereas the expression of the cation-independent MPR was higher in SM than SI bulls. In addition, the four enzymesrecovered from the epididymal lumen interact with both MPRs at each age. We conclude that the activity and distributionof LE in bull epididymis varies with sexual maturity and that the distribution is regulated differently by the two types ofMPR. These findings could provide some molecular basis for male infertility.