title: CD9 tetraspanin generates fusion competent sites on the egg membrane for mammalian fertilization.
abstract: CD9 tetraspanin is the only egg membrane protein known to be essential for fertilization. To investigate its role, we have measured, on a unique acrosome reacted sperm brought in contact with an egg, the adhesion probability and strength with a sensitivity of a single molecule attachment. Probing the binding events at different locations of wild-type egg we described different modes of interaction. Here, we show that more gamete adhesion events occur on Cd9 null eggs but that the strongest interaction mode disappears. We propose that sperm-egg fusion is a direct consequence of CD9 controlled sperm-egg adhesion properties. CD9 generates adhesion sites responsible for the strongest of the observed gamete interaction. These strong adhesion sites impose, during the whole interaction lifetime, a tight proximity of the gamete membranes, which is a requirement for fusion to take place. The CD9-induced adhesion sites would be the actual location where fusion occurs.
authors.affiliation: Laboratoire de Physique Statistique, Ecole Normale Supérieure de Paris, Université Pierre et Marie Curie, Université Paris Diderot, Centre National de la Recherche Scientifique, 24 rue Lhomond, 75005 Paris, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Jégou
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ziyyat
authors.forename: Virginie
authors.initials: V
authors.lastname: Barraud-Lange
authors.forename: Eric
authors.initials: E
authors.lastname: Perez
authors.forename: Jean Philippe
authors.initials: JP
authors.lastname: Wolf
authors.forename: Frédéric
authors.initials: F
authors.lastname: Pincet
authors.forename: Christine
authors.initials: C
authors.lastname: Gourier
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000502:physiology*; D001665:Binding Sites; D002448:Cell Adhesion / Q000502:physiology; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro; D008297:Male; D008561:Membrane Fusion / Q000502:physiology; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D008871:Microvilli / Q000502:physiology; D008954:Models, Biological; D010063:Ovum / Q000502:physiology*; D013084:Sperm-Ovum Interactions / Q000502:physiology; D060245:Tetraspanin 29
chemical_list: D015703:Antigens, CD; C554870:Cd9 protein, mouse; D008562:Membrane Glycoproteins; D060245:Tetraspanin 29