(P-502) Sperm Maturation Regulates Function and Binding of Sperm to Complex and Hybrid N-Linked Oligosaccharides

Abstract Authors: Leonardo Molina¹, Kevin Lam², Kankanit Doungkamchan¹, Carlo Unverzagt² & David Miller¹

1. Department of Animal Sciences and Institute of Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, United States.

2. Bioorganic Chemistry, University of Bayreuth, Bayreuth, Germany.

Abstract Text: Following insemination in mammals, sperm journey through the female reproductive tract to reach the site of fertilization. At the lower oviduct, a carbohydrate-mediated adhesion between sperm and the oviduct epithelium helps form the sperm reservoir. The sperm reservoir can extend the fertilization window by regulating sperm survival and the availability of fertilization-competent sperm at the time of ovulation. Carbohydrate-dependent interactions may also mediate the primary adhesion between spermatozoa and the zona pellucida in a similar carbohydrate-dependent fashion. However, the glycan molecular mediators involved in these interactions remain to be elucidated in detail. This study utilized a novel glycan array containing 140 hybrid and complex multi-antennary oligosaccharides to high-throughput-screen glycan structures that permit sperm tethering. We found that porcine sperm have a high affinity for multi-antennary glycans containing a bisecting GlcNAc and terminating Gal(β1-4)GlcNAc or Neu5Ac(α2-6)Gal motifs. Compared to bi-antennary glycans, porcine sperm tethering is enhanced by tetra-antennary and tri-antennary structures with a core GlcNAc(β1-4)Man linkage. Sperm maturation did not impact glycan tethering except for capacitated sperm’s increased preference for Neu5Ac-terminating glycans. Last, we found that sperm tethering by glycans in this array could impact sperm function. Sperm tethered by glycans in the array underwent lower rates of calcium ionophore-induced acrosome reaction when compared to free sperm. This suggests that a delay in sperm capacitation could be mediated by a glycan-mediated mechanism that can be replicated in-vitro. This work was supported by the National Institutes of Health [RO1HD095841 to D.M., T32EB019944 to L.M., and 1F31HD108959 to L.M.].