Reassessing the molecular biology of sperm-egg recognition with mouse genetics.
The zona pellucida is an extracellular coat that surrounds mammalian eggs and early embryos. This insoluble matrix separates germ from somatic cells during folliculogenesis and plays critical roles during fertilization and early development. The mouse and human zona pellucida contain three glycoproteins (ZP1 or ZPB, ZP2, ZP3), the primary structures of which have been deduced by molecular cloning. Targeted mutagenesis of endogenous mouse genes and transgenesis with human homologues provide models to investigate the roles of individual zona components. Collectively, the genetic data indicate that no single mouse zona pellucida protein is obligatory for taxon-specific sperm binding and that two human proteins are not sufficient to support human sperm binding. An observed post-fertilization persistence of mouse sperm binding to "humanized" zona pellucida correlates with uncleaved ZP2. These observations are consistent with a model for sperm binding in which the supramolecular structure of the zona pellucida necessary for sperm binding is modulated by the cleavage status of ZP2.
Dean
Jurrien
J
Laboratory of Cellular and Developmental Biology, NIDDK, Building 50, Room 3134, National Institutes of Health, 50 South Drive, Bethesda, Maryland 20892, USA. jurrien@helix.nih.gov
D000818:Animals; D006224:Cricetinae; D004527:Egg Proteins / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D011956:Receptors, Cell Surface; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology; D019076:Transgenes; D015044:Zona Pellucida / Q000473:pathology / Q000502:physiology; D000072216:Zona Pellucida Glycoproteins
D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C000606514:ZP1 protein, human; C000606515:ZP2 protein, human; C000606517:ZP3 protein, human; D000072216:Zona Pellucida Glycoproteins; C000606519:Zp1 protein, mouse; C000606520:Zp2 protein, mouse; C000606521:Zp3 protein, mouse