Occurrence of novel Cu2+-dependent sialic acid-specific lectin, on the outer surface of mature caprine spermatozoa

Abstract

Effects of several bivalent metal ions on the autoagglutination event in mature caprine epididymal sperm cells have been investigated using a chemically defined medium. This study demonstrates for the first time that Copper (Cu(2+)) ion (300 μM) has high specificity for autoagglutination of mature cauda-epididymal sperm. Head-to-head interaction of the male gametes is responsible for this event. Studies on the effect of various sugars reveal that the autoagglutinated cells can be dissociated specifically with neutralized sialic acid (50 mM), which also inhibits the sperm cell autoagglutination phenomenon. Blood serum protein fetuin, that contains terminal sialic acid residue, showed high efficacy for inhibiting this autoagglutination event at 4 μM concentration. However, asialofetuin is not capable of inhibiting this Cu(2+)-dependent cellular event. Mature sperm cells bound with caprine erythrocytes at their head region in presence of Cu(2+) ion. The purified sperm membrane fraction isolated by aqueous two phase polymer method showed high efficacy to agglutinate erythrocytes. These sperm-erythrocyte interactions as well as sperm membrane induced haemagglutination were strongly blocked by neutralized sialic acid (50 mM). The results confirm the occurrence of unique Cu(2+) dependent, sialic acid-specific lectin on the outer surface of a mammalian cell using caprine sperm as the model. The observed Cu(2+)-mediated cellular autoagglutination is caused by the interaction of the cell surface lectin with the lectin receptor on the surface of the neighboring homologous cell.

Removal of sialic acid from bull sperm decreases motility and mucus penetration ability but increases zona pellucida binding and polyspermic penetration in vitro

“…In order to fulfil this goal, the male gamete must be able to transverse the mucus-lined female reproductive tract, evade the immune surveillance of the female, interact with the cumulus cells and selectively bind the ZP and the plasma membrane of the oocyte. A growing body of evidence links glycans and glycanbinding molecules to most of these sperm functional roles (Yudin et al 2005, Tollner et al 2008a,b, Kadirvel et al 2012, Roy et al 2014. Changes in the sperm glycome occur due to proteolysis, shedding or incorporation of glycoproteins that takes place during the epididymal transit (Toshimori et al 1988, 1991, Tollner et al 2008a,b, Yudin et al 2005 n blastocyst/n oocytes fertilized et al 2016).…”

D-penicillamine prevents ram sperm agglutination by reducing the disulphide bonds of a copper-binding sperm protein

“…The percentage of motile, non-agglutinated spermatozoa supplemented with 0 (3.2 ± 1.1%), 1 (3.0 ± 1.3%), 10 (3.5 ± 0.9%), 20 (3.8 ± 0.9%) or 30 (3.8 ± 1.0%) mM sialic acid was low and statistically similar. This suggests that the mechanism of sperm binding described herein does not involve a sialic acid-specific lectin as shown in goat spermatozoa (Roy et al 2014).…”

“…A copper-dependent lectin that causes sperm agglutination has been observed on the outer membrane of mature caprine spermatozoa (Roy et al 2014). This lectin was sialic acid specific, and agglutinated cells could be dissociated with neutralised sialic acid.…”

“…-dependent lectin associated with agglutination of goat spermatozoa has been described (Roy et al 2014). The lectin was sialic acid-specific and agglutinated cells could be dissociated with neutralised sialic acid (Roy et al 2014).…”

“…The lectin was sialic acid-specific and agglutinated cells could be dissociated with neutralised sialic acid (Roy et al 2014). The aim of Experiment 3 was to assess the response of 0, 1, 10, 20 or 30 mM N-acetylneuraminic acid (sialic acid; Cayman Chemicals) on TALP-induced ram sperm agglutination.…”