This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Objective: Our lab has had a long standing interest in identifying and characterizing sperm surface proteins that play a role in the interaction of sperm with the fluids and cells of the female reproductive tract. Our findings in non-human primates are relevant to issues in human reproduction, providing insights into causes of infertility as well as identifying possible targets for contraception. We previously reported that DEFB126 (formerly ESP13.2) coats the entire surface of macaque sperm and remains until sperm become capacitated. The release of DEFB126 from sperm during capacitation is required for sperm recognition and binding of the zona pellucida, suggesting that DEFB126 masks zona pellucida ligands on the sperm surface. Furthermore, DEFB126 appears to masks all sperm surface components and protects sperm from immune recognition. Immunoprotection appears to stem from the highly glycosylated carboxyl domain which is comprised of oligosaccharides that terminate in sialic acid. DEFB126 provides uniform negative charge over the surface of sperm that is significantly reduced as sperm release DEFB126 during capacitation.
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