title: Sialidases on mammalian sperm mediate deciduous sialylation during capacitation.
abstract: Sialic acids (Sias) mediate many biological functions, including molecular recognition during development, immune response, and fertilization. A Sia-rich glycocalyx coats the surface of sperm, allowing them to survive as allogeneic cells in the female reproductive tract despite female immunity. During capacitation, sperm lose a fraction of their Sias. We quantified shed Sia monosaccharides released from capacitated sperm and measured sperm sialidase activity. We report the presence of two sialidases (neuraminidases Neu1 and Neu3) on mammalian sperm. These are themselves shed from sperm during capacitation. Inhibiting sialidase activity interferes with sperm binding to the zona pellucida of the ovum. A survey of human sperm samples for the presence of sialidases NEU1 and NEU3 identified a lack of one or both sialidases in sperm of some male idiopathic infertility cases. The results contribute new insights into the dynamic remodeling of the sperm glycocalyx prior to fertilization.
authors.affiliation: Glycobiology Research and Training Center and Departments of Cellular, University of California, San Diego, La Jolla, California 92093-0687, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Ma
authors.forename: Diana
authors.initials: D
authors.lastname: Wu
authors.forename: Liwen
authors.initials: L
authors.lastname: Deng
authors.forename: Patrick
authors.initials: P
authors.lastname: Secrest
authors.forename: June
authors.initials: J
authors.lastname: Zhao
authors.forename: Nissi
authors.initials: N
authors.lastname: Varki
authors.forename: Steven
authors.initials: S
authors.lastname: Lindheim
authors.forename: Pascal
authors.initials: P
authors.lastname: Gagneux
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004822:Epididymis / Q000201:enzymology / Q000378:metabolism; D005260:Female; D005306:Fertilization; D005434:Flow Cytometry; D019276:Glycocalyx / Q000378:metabolism; D006801:Humans; D007248:Infertility, Male / Q000201:enzymology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009005:Monosaccharides / Q000378:metabolism; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009439:Neuraminidase / Q000378:metabolism*; D013075:Sperm Capacitation; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000201:enzymology* / Q000378:metabolism; D013737:Testis / Q000201:enzymology / Q000378:metabolism; D015044:Zona Pellucida / Q000378:metabolism
chemical_list: D009005:Monosaccharides; C486385:NEU1 protein, human; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid