title: CAR expression in human embryos and hESC illustrates its role in pluripotency and tight junctions.
abstract: Coxsackie virus and adenovirus receptor, CXADR (CAR), is present during embryogenesis and is involved in tissue regeneration, cancer and intercellular adhesion. We investigated the expression of CAR in human preimplantation embryos and embryonic stem cells (hESC) to identify its role in early embryogenesis and differentiation. CAR protein was ubiquitously present during preimplantation development. It was localised in the nucleus of uncommitted cells, from the cleavage stage up to the precursor epiblast, and corresponded with the presence of soluble CXADR3/7 splice variant. CAR was displayed on the membrane, involving in the formation of tight junction at compaction and blastocyst stages in both outer and inner cells, and CAR corresponded with the full-length CAR-containing transmembrane domain. In trophectodermal cells of hatched blastocysts, CAR was reduced in the membrane and concentrated in the nucleus, which correlated with the switch in RNA expression to the CXADR4/7 and CXADR2/7 splice variants. The cells in the outer layer of hESC colonies contained CAR on the membrane and all the cells of the colony had CAR in the nucleus, corresponding with the transmembrane CXADR and CXADR4/7. Upon differentiation of hESC into cells representing the three germ layers and trophoblast lineage, the expression of CXADR was downregulated. We concluded that CXADR is differentially expressed during human preimplantation development. We described various CAR expressions: i) soluble CXADR marking undifferentiated blastomeres; ii) transmembrane CAR related with epithelial-like cell types, such as the trophectoderm (TE) and the outer layer of hESC colonies; and iii) soluble CAR present in TE nuclei after hatching. The functions of these distinct forms remain to be elucidated.
authors.affiliation: Research Group Reproduction and GeneticsFaculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, BelgiumCentre for Reproductive Medicine (CRG)UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium mkrivega@vub.ac.be.
authors.forename: M
authors.initials: M
authors.lastname: Krivega
authors.affiliation: Research Group Reproduction and GeneticsFaculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, BelgiumCentre for Reproductive Medicine (CRG)UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Geens
authors.affiliation: Research Group Reproduction and GeneticsFaculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, BelgiumCentre for Reproductive Medicine (CRG)UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium Research Group Reproduction and GeneticsFaculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, BelgiumCentre for Reproductive Medicine (CRG)UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Van de Velde
mesh_terms: D021581:Active Transport, Cell Nucleus; D001755:Blastocyst / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D019070:Cell Lineage; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein / Q000235:genetics / Q000378:metabolism*; D046149:Embryo Culture Techniques; D053595:Embryonic Stem Cells / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D039904:Pluripotent Stem Cells / Q000378:metabolism*; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D019108:Tight Junctions / Q000378:metabolism*
chemical_list: C568771:CLMP protein, human; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D020033:Protein Isoforms; D012333:RNA, Messenger