Poster Presentation The Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology 2014

Proteomic analysis of glycoproteins during sperm epididymal maturation (#355)

Ana Izabel S.B. Villaverde 1 , Louise Hetherington 1 , Anita Weinberg 1 , Mark A. Baker 1
  1. Priority Research Centre in Reproductive Biology, Reproductive Proteomics, University of Newcastle, Callaghan, NSW, Australia

The fertilizing potential of sperm cells is acquired as they undergo a series of post-translational modifications during epididymal transit. On major facet of such, are changes in the sperm glycome. The aim of the present study was to identify N-linked sialoglycoproteins in rat epididymal sperm and investigate whether they are regulated during epididymal transit. Sialic acids are usually found capping N- and O-glycans end sites in glycoproteins and participate in cellular adhesion and signaling. As such, it was of interest to understand the changes in sialic acid content of sperm proteins during epididymal maturation. Spermatozoa were taken from the caput, corpus or caudal regions of rat epididymis. Sialoglycopeptides were enriched using titanium dioxide beads and following PNGase F treatment, the peptides were then analyzed using liquid chromatography coupled to mass spectrometry.  A total of 94 N-linked sialoglycopeptides comprising of 65 proteins were found in at least one epididymal region. Remarkably, 42 peptides were regulated during epididymal transit, suggesting that changes in the sialome are a major hallmark of sperm maturation.  Several notable proteins, including members of the Disintegrin and metalloproteinase domain-containing protein family, Angiotensin-converting enzyme and Basigin underwent major modifications in their sialic acid content. In correlation with this, Basigin is known to undergo major sub-cellular relocalisation during this same time frame, suggesting an involvement in events such as sperm capacitation. In conclusion, quantification of sialic acid glycoproteins has enriched for many notable proteins that play a major role in sperm maturation. Current work is ascribing these proteins to events such as capacitation.