title: Removal of GPI-anchored membrane proteins causes clustering of lipid microdomains in the apical head area of porcine sperm.
abstract: The release of extracellular proteins is a part of the sperm capacitation process; this allows the sperm surface reorganization that enables the sperm to fertilize an oocyte. Some of the components released are 'decapacitation factors', an uncoordinated or early release of which may cause inappropriate surface destabilization and premature capacitation. We studied the involvement of glycosylphosphatidylinositol-anchored proteins (GPI-APs) in sperm capacitation, and reported that CD52 and CD55 exhibit bicarbonate-dependent release during in vitro sperm capacitation. Treating sperm with phosphatidylinositol-specific phospholipase C (PIPLC) resulted in the enzymatic cleavage of CD55, in both capacitating and noncapacitating conditions. Moreover, PIPLC treatment in noncapacitating conditions caused surface reorganization events that included exposure of the ganglioside GM1, aggregation of flotillin-1, and the swelling of the apical acrosome region; all of which have been reported to be associated with sperm capacitation. The acrosomal swelling was monitored using wet mount atomic force microscopy, a new imaging technique that allows nanometer-level sperm surface measurements in samples hydrated with physiological buffer rather than dried. Despite these surface changes, PIPLC treatment in identical incubation conditions did not stimulate hyperactive sperm motility or protein tyrosine phosphorylation (other hallmarks of sperm capacitation in vitro). In full capacitating conditions (i.e., the presence of bicarbonate and albumin), PIPLC treatment caused sperm deterioration. The possible role of GPI-APs removal from the sperm surface during sperm capacitation is discussed.
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands; Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Arjan
authors.initials: A
authors.lastname: Boerke
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: van der Lit
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Francesca
authors.initials: F
authors.lastname: Lolicato
authors.affiliation: Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands; Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Tom A E
authors.initials: TA
authors.lastname: Stout
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: J Bernd
authors.initials: JB
authors.lastname: Helms
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands; Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. Electronic address: b.m.gadella@uu.nl.
authors.forename: Bart M
authors.initials: BM
authors.lastname: Gadella
mesh_terms: D000177:Acrosome / Q000502:physiology; D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D000951:Antigens, Neoplasm / Q000502:physiology*; D000074301:CD52 Antigen; D018958:CD55 Antigens / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D005732:Gangliosides / Q000502:physiology*; D006023:Glycoproteins / Q000502:physiology*; D015151:Immunoblotting / Q000662:veterinary; D008297:Male; D018625:Microscopy, Atomic Force / Q000662:veterinary; D013075:Sperm Capacitation / Q000502:physiology*; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology*; D013552:Swine / Q000502:physiology*; D010738:Type C Phospholipases / Q000494:pharmacology
chemical_list: D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000074301:CD52 Antigen; D018958:CD55 Antigens; D005732:Gangliosides; D006023:Glycoproteins; D010738:Type C Phospholipases
keywords: Glycosylphosphatidylinositol-anchored protein release; Membrane raft; Phosphatidyl inositol specific phospholipase C; Sperm capacitation