Cholesterol depletion disorganizes oocyte membrane rafts altering mouse fertilization

• Published in: PloS one Vol. 8; no. 4; p. e62919
• Main Authors: Buschiazzo, Jorgelina, Ialy-Radio, Come, Auer, Jana, Wolf, Jean-Philippe, Serres, Catherine, Lefèvre, Brigitte, Ziyyat, Ahmed
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25-04-2013; Public Library of Science (PLoS)
• Subjects: Animals; Biological Transport - drug effects; Biology; Boron Compounds - metabolism; Caveolae; Caveolin; Caveolin 1 - metabolism; Caveolin-1; Cell Survival - drug effects; Cholesterol; Cholesterol - deficiency; Coexistence; Cyclodextrin; Cyclodextrins; Depletion; Eggs; Electron microscopy; Extrusion rate; Female; Fertilization; Fertilization - drug effects; Fluorescence; Fuses; G(M1) Ganglioside - metabolism; Ganglioside GM1; Gangliosides; Glycosylphosphatidylinositol; In vitro fertilization; Intracellular Space - drug effects; Intracellular Space - metabolism; Invaginations; Kinases; Laboratories; Lipid rafts; Lipids; Localization; Male; Membrane Microdomains - drug effects; Membrane Microdomains - metabolism; Membrane proteins; Membrane Proteins - metabolism; Membranes; Methyl-β-Cyclodextrin; Mice; Mineral oils; Oocytes; Oocytes - cytology; Oocytes - drug effects; Oocytes - metabolism; Ovulation - drug effects; Protein families; Protein Kinase Inhibitors - pharmacology; Proteins; Proto-Oncogene Proteins pp60(c-src) - antagonists & inhibitors; Proto-Oncogene Proteins pp60(c-src) - metabolism; Rafts; Signaling; Sperm; Src protein; Tetraspanins - metabolism; France
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0062919

Drastic membrane reorganization occurs when mammalian sperm binds to and fuses with the oocyte membrane. Two oocyte protein families are essential for fertilization, tetraspanins and glycosylphosphatidylinositol-anchored proteins. The firsts are associated to tetraspanin-enriched microdomains and the seconds to lipid rafts. Here we report membrane raft involvement in mouse fertilization assessed by cholesterol modulation using methyl-β-cyclodextrin. Cholesterol removal induced: (1) a decrease of the fertilization rate and index; and (2) a delay in the extrusion of the second polar body. Cholesterol repletion recovered the fertilization ability of cholesterol-depleted oocytes, indicating reversibility of these effects. In vivo time-lapse analyses using fluorescent cholesterol permitted to identify the time-point at which the probe is mainly located at the plasma membrane enabling the estimation of the extent of the cholesterol depletion. We confirmed that the mouse oocyte is rich in rafts according to the presence of the raft marker lipid, ganglioside GM1 on the membrane of living oocytes and we identified the coexistence of two types of microdomains, planar rafts and caveolae-like structures, by terms of two differential rafts markers, flotillin-2 and caveolin-1, respectively. Moreover, this is the first report that shows characteristic caveolae-like invaginations in the mouse oocyte identified by electron microscopy. Raft disruption by cholesterol depletion disturbed the subcellular localization of the signal molecule c-Src and the inhibition of Src kinase proteins prevented second polar body extrusion, consistent with a role of Src-related kinases in fertilization via signaling complexes. Our data highlight the functional importance of intact membrane rafts for mouse fertilization and its dependence on cholesterol.