title: Two pathways regulate cortical granule translocation to prevent polyspermy in mouse oocytes.
abstract: An egg must be fertilized by a single sperm only. To prevent polyspermy, the zona pellucida, a structure that surrounds mammalian eggs, becomes impermeable upon fertilization, preventing the entry of further sperm. The structural changes in the zona upon fertilization are driven by the exocytosis of cortical granules. These translocate from the oocyte's centre to the plasma membrane during meiosis. However, very little is known about the mechanism of cortical granule translocation. Here we investigate cortical granule transport and dynamics in live mammalian oocytes by using Rab27a as a marker. We show that two separate mechanisms drive their transport: myosin Va-dependent movement along actin filaments, and an unexpected vesicle hitchhiking mechanism by which cortical granules bind to Rab11a vesicles powered by myosin Vb. Inhibiting cortical granule translocation severely impaired the block to sperm entry, suggesting that translocation defects could contribute to miscarriages that are caused by polyspermy.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
authors.forename: Liam P
authors.initials: LP
authors.lastname: Cheeseman
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Boulanger
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Bond
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.|Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany.
authors.forename: Melina
authors.initials: M
authors.lastname: Schuh
mesh_terms: D000818:Animals; D015415:Biomarkers; D003594:Cytoplasmic Granules / Q000502:physiology*; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D008297:Male; D051379:Mice; D009865:Oocytes / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology*; D000075745:rab27 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000075745:rab27 GTP-Binding Proteins; C512962:Rab27a protein, mouse