title: Contribution of JAM-1 to epithelial differentiation and tight-junction biogenesis in the mouse preimplantation embryo.
abstract: We have investigated the contribution of the tight junction (TJ) transmembrane protein junction-adhesion-molecule 1 (JAM-1) to trophectoderm epithelial differentiation in the mouse embryo. JAM-1-encoding mRNA is expressed early from the embryonic genome and is detectable as protein from the eight-cell stage. Immunofluorescence confocal analysis of staged embryos and synchronized cell clusters revealed JAM-1 recruitment to cell contact sites occurred predominantly during the first hour after division to the eight-cell stage, earlier than any other TJ protein analysed to date in this model and before E-cadherin adhesion and cell polarization. During embryo compaction later in the fourth cell cycle, JAM-1 localized transiently yet precisely to the apical microvillous pole, where protein kinase Czeta (PKCzeta) and PKCdelta are also found, indicating a role in cell surface reorganization and polarization. Subsequently, in morulae and blastocysts, JAM-1 is distributed ubiquitously at cell contact sites within the embryo but is concentrated within the trophectoderm apicolateral junctional complex, a pattern resembling that of E-cadherin and nectin-2. However, treatment of embryos with anti-JAM-1-neutralizing antibodies indicated that JAM-1 did not contribute to global embryo compaction and adhesion but rather regulated the timing of blastocoel cavity formation dependent upon establishment of the trophectoderm TJ paracellular seal.
authors.affiliation: School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, SO16 7PX, UK.
authors.forename: Fay C
authors.initials: FC
authors.lastname: Thomas
authors.forename: Bhavwanti
authors.initials: B
authors.lastname: Sheth
authors.forename: Judith J
authors.initials: JJ
authors.lastname: Eckert
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Bazzoni
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Dejana
authors.forename: Tom P
authors.initials: TP
authors.lastname: Fleming
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology; D015536:Down-Regulation / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D008297:Male; D051379:Mice; D008871:Microvilli / Q000378:metabolism / Q000648:ultrastructure; D000075983:Nectins; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D019108:Tight Junctions / Q000502:physiology*
chemical_list: D015820:Cadherins; D015815:Cell Adhesion Molecules; C498686:F11r protein, mouse; D000075983:Nectins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface