title: Expression and putative function of fibronectin and its receptor (integrin alpha(5)beta(1)) in male and female gametes during bovine fertilization in vitro.
abstract: Fibronectin (Fn) is a 440 kDa glycoprotein assumed to participate in sperm-egg interaction in human. Recently, it has been demonstrated that Fn--when present during bovine IVF--strongly inhibits sperm penetration. The present study was conducted firstly to evaluate the expression of Fn and its integrin receptor (alpha(5)beta(1)) on male and female bovine gametes using indirect immunofluorescence and secondly, to determine the function of Fn during bovine IVF. Endogenous Fn was detected underneath the zona pellucida (ZP) and integrin alpha(5) on the oolemma of cumulus-denuded oocytes. Bovine spermatozoa displayed integrin alpha(5) at their equatorial segment after acrosome reaction. We established that the main inhibitory effect of exogenously supplemented Fn was located at the sperm-oolemma binding, with a (concurrent) effect on fusion, and this can probably be attributed to the binding of Fn to spermatozoa at the equatorial segment, as shown by means of Alexa Fluor 488-conjugated Fn. Combining these results, the inhibitory effect of exogenously supplemented Fn seemed to be exerted on the male gamete by binding to the exposed integrin alpha(5)beta(1) receptor after acrosome reaction. The presence of endogenous Fn underneath the ZP together with integrin alpha(5) expression on oolemma and acrosome-reacted (AR) sperm cell surface suggests a 'velcro' interaction between the endogenous Fn ligand and corresponding receptors on both (AR) sperm cell and oolemma, initiating sperm-egg binding.
authors.affiliation: Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Mirjan
authors.initials: M
authors.lastname: Thys
authors.forename: Hans
authors.initials: H
authors.lastname: Nauwynck
authors.forename: Dominiek
authors.initials: D
authors.lastname: Maes
authors.forename: Maarten
authors.initials: M
authors.lastname: Hoogewijs
authors.forename: Dries
authors.initials: D
authors.lastname: Vercauteren
authors.forename: Tom
authors.initials: T
authors.lastname: Rijsselaere
authors.forename: Herman
authors.initials: H
authors.lastname: Favoreel
authors.forename: Ann
authors.initials: A
authors.lastname: Van Soom
mesh_terms: D020101:Acrosome Reaction / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002417:Cattle / Q000378:metabolism / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D005306:Fertilization / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D005307:Fertilization in Vitro / Q000187:drug effects / Q000662:veterinary; D005353:Fibronectins / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D005854:Germ Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D039081:Integrin alpha5beta1 / Q000378:metabolism* / Q000502:physiology*; D008297:Male; D013084:Sperm-Ovum Interactions / Q000187:drug effects / Q000502:physiology; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D014018:Tissue Distribution; D015044:Zona Pellucida / Q000378:metabolism
chemical_list: D005353:Fibronectins; D039081:Integrin alpha5beta1