title: Lipid rafts enriched in monosialylGb5Cer carrying the stage-specific embryonic antigen-4 epitope are involved in development of mouse preimplantation embryos at cleavage stage.
abstract: BACKGROUND
  Lipid rafts enriched in glycosphingolipids (GSLs), cholesterol and signaling molecules play an essential role not only for signal transduction started by ligand binding, but for intracellular events such as organization of actin, intracellular traffic and cell polarity, but their functions in cleavage division of preimplantation embryos are not well known.
  
  
  RESULTS
  Here we show that monosialylGb5Cer (MSGb5Cer)-enriched raft domains are involved in development during the cleavage stage of mouse preimplantation embryos. MSGb5Cer preferentially localizes at the interfaces between blastomeres in mouse preimplantation embryos. Live-imaging analysis revealed that MSGb5Cer localizes in cleavage furrows during cytokinesis, and that by accumulating at the interfaces, it thickens them. Depletion of cholesterol from the cell membrane with methyl-beta-cyclodextrin (MbCD) reduced the expression of MSGb5Cer and stopped cleavage. Extensive accumulation of MSGb5Cer at the interfaces by cross-linking with anti-MSGb5Cer Mab (6E2) caused F-actin to aggregate at the interfaces and suppressed the localization of E-cadherin at the interfaces, which resulted in the cessation of cleavage. In addition, suppression of actin polymerization with cytochalasin D (CCD) decreased the accumulation of MSGb5Cer at the interfaces. In E-cadherin-targeted embryos, the MSGb5Cer-enriched raft membrane domains accumulated heterotopically.
  
  
  CONCLUSIONS
  These results indicate that MSGb5Cer-enriched raft membrane domains participate in cytokinesis in a close cooperation with the cortical actin network and the distribution of E-cadherin.
authors.affiliation: Department of Pediatric Hematology and Oncology Research, National Research Institute for Child Health and Development, 2-10-1 Okura, Tokyo 157-8535, Japan.
authors.forename: Ban
authors.initials: B
authors.lastname: Sato
authors.forename: Yohko U
authors.initials: YU
authors.lastname: Katagiri
authors.forename: Kenji
authors.initials: K
authors.lastname: Miyado
authors.forename: Nozomu
authors.initials: N
authors.lastname: Okino
authors.forename: Makoto
authors.initials: M
authors.lastname: Ito
authors.forename: Hidenori
authors.initials: H
authors.lastname: Akutsu
authors.forename: Hajime
authors.initials: H
authors.lastname: Okita
authors.forename: Akihiro
authors.initials: A
authors.lastname: Umezawa
authors.forename: Junichiro
authors.initials: J
authors.lastname: Fujimoto
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Toshimori
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Kiyokawa
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D002970:Cleavage Stage, Ovum / Q000378:metabolism*; D048749:Cytokinesis / Q000502:physiology; D005260:Female; D005677:G(M1) Ganglioside / Q000378:metabolism; D005915:Globosides / Q000378:metabolism*; D008297:Male; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D011247:Pregnancy; D015398:Signal Transduction; D055746:Stage-Specific Embryonic Antigens / Q000378:metabolism*; D047392:beta-Cyclodextrins
chemical_list: D000199:Actins; D015820:Cadherins; D005915:Globosides; D055746:Stage-Specific Embryonic Antigens; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C066584:stage-specific embryonic antigen-4; D005677:G(M1) Ganglioside; D002784:Cholesterol