Hexosaminidase from cauda epididymal fluid may be active in the remodeling of bull spermatozoa surface.

ALVAREZ P; BUTAZZONNI A; SOSA MA; ROBINA I; AGUILERA AC

Mendoza

Congreso; Cuyo Biology Society XXXIX; 2021

Sociedad de Biología de Cuyo

Spermatozoa undergo biochemical and morphological changes during the epididymal maturation that results in a gamete competent for fertilization. Among the several proteins secreted by the epididymal epithelium, hexosaminidase (HEX) is the most abundant glycosidase in bull epididymis and represents upon 3% of the total secretion in the distal part of this organ. Taking into account the lysosomal origin of HEX, it is not known whether this enzyme is active at physiological pH and participates in the epididymal maturation. The aim of this study was to correlate the enzymatic activity of HEX with the changes observed in N-acetyl-glucosamine (NAG) content in bull spermatozoa during epididymal maturation. By flow cytometry and fluorescence microscopy, we analyzed the NAG content using WGA FITC and observed a remodeling of the NAG content during epididymal maturation. Interestingly, an increased activity of HEX was detected in the cauda lumen at the physiological epididymal pH (6,8) using 4ME-umbiliferone-based substrate. In order to determine if HEX from epididymal lumen is responsible of NAG removal from the sperm surface, we performed an incubation assay using cauda fluid with spermatozoa obtained from the caput region. After the incubation we observed by flow cytometry a significant decrease of NAG detection which was partially reversed with synthetic specific inhibitors 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.