PMID:15494378

Citation	Thomas, FC, Sheth, B, Eckert, JJ, Bazzoni, G, Dejana, E and Fleming, TP (2004) Contribution of JAM-1 to epithelial differentiation and tight-junction biogenesis in the mouse preimplantation embryo. J. Cell. Sci. 117:5599-608
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.
Links	PubMed Online version:10.1242/jcs.01424
Keywords	Adherens Junctions/metabolism; Animals; Blastocyst/physiology; Cadherins/metabolism; Cell Adhesion/physiology; Cell Adhesion Molecules/genetics; Cell Adhesion Molecules/metabolism; Cell Differentiation/physiology; Cell Polarity/physiology; Down-Regulation/physiology; Embryonic Development/physiology; Epithelial Cells/cytology; Epithelial Cells/metabolism; Female; Gene Expression Regulation, Developmental/physiology; Male; Mice; Microvilli/metabolism; Microvilli/ultrastructure; RNA, Messenger/metabolism; Receptors, Cell Surface/genetics; Receptors, Cell Surface/metabolism; Tight Junctions/physiology
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