Hexosaminidase from cauda epididymal fluid could participate in remodeling carbohydrate on the surface of bull spermatozoa

ALVAREZ P; BUTAZZONI A; MIGUEL A. SOSA; ROBINA I; AGUILERA AC

Congreso; XXXVII Reunión Anual de la Sociedad de Biología de Cuyo; 2021

permatozoa undergo biochemical and morphological changes during the epididymal transit, resulting in the gamete maturation. Among the several proteins secreted by the epididymal epithelium, hexosaminidase (HEX) is the most abundant glycosidase in bull epididymal fluid and it represents upon 3% of the total secretion in the distal part of the organ. Given that HEX is a lysosomal enzyme, it is still controvertial whether this enzyme is active at the pH of the epididymal lumen and and whether it participates in the epididymal maturation. The aim of this study was to correlate the activity of HEX with those changes in N-acetyl-glucosamine (NAG) content observed in bull spermatozoa during epididymal maturation. By flow cytometry and fluorescence microscopy (using WGA FITC), we observed that NAG content on the sperm surface varies during epididymal maturation. Interestingly, increased activity of HEX (measured by spectrofluorometry) at the epididymal pH (6.8) was detected in the cauda lumen. In order to determine if the epididymal HEX is responsible for NAG removal from the sperm surface, we performed an assay by incubating cauda fluid with spermatozoa obtained from the caput. We observed by flow cytometry that incubation with the fluid induced a significant decrease of NAG on the sperm surface, which was partially reversed with synthetic inhibitors specific for HEX. Our results provide direct evidence that HEX from epididymal fluid may participates in removing NAG from spermatozoa, as a step of sperm maturation in bull epididymis.