title: Distinct mechanisms regulate Cdx2 expression in the blastocyst and in trophoblast stem cells.
abstract: The first intercellular differences during mammalian embryogenesis arise in the blastocyst, producing the inner cell mass and the trophectoderm. The trophectoderm is the first extraembryonic tissue and does not contribute to the embryo proper, its differentiation instead forming tissues that sustain embryonic development. Crucial roles in extraembryonic differentiation have been identified for certain transcription factors, but a comprehensive picture of the regulation of this early specification is still lacking. Here, we investigated whether the regulatory mechanisms involved in Cdx2 expression in the blastocyst are also utilized in the postimplantation embryo. We analyzed an enhancer that is regulated through Hippo and Notch in the blastocyst trophectoderm, unexpectedly finding that it is inactive in the extraembryonic structures at postimplantation stages. Further analysis identified other Cdx2 regulatory elements including a stem-cell specific regulatory sequence and an element that drives reporter expression in the trophectoderm, a subset of cells in the extraembryonic region of the postimplantation embryo and in trophoblast stem cells. The cross-comparison in this study of cis-regulatory elements employed in the blastocyst, stem cell populations and the postimplantation embryo provides new insights into early mammalian development and suggests a two-step mechanism in Cdx2 regulation.
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Rayon
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Menchero
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Rollán
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Ors
authors.affiliation: Epigenetics and Development Group; Institute of Reproductive and Developmental Biology; Faculty of Medicine; Imperial College London; London, W12 ONN UK.
authors.forename: Anne
authors.initials: A
authors.lastname: Helness
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Crespo
authors.affiliation: Program in Developmental and Stem Cell Biology, Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
authors.forename: Andres
authors.initials: A
authors.lastname: Nieto
authors.affiliation: Epigenetics and Development Group; Institute of Reproductive and Developmental Biology; Faculty of Medicine; Imperial College London; London, W12 ONN UK.
authors.forename: Véronique
authors.initials: V
authors.lastname: Azuara
authors.affiliation: Program in Developmental and Stem Cell Biology, Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, ON M5G 0A4, Canada.|Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
authors.forename: Janet
authors.initials: J
authors.lastname: Rossant
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Manzanares
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism*; D000071616:CDX2 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D010064:Embryo Implantation; D047108:Embryonic Development; D004742:Enhancer Elements, Genetic; D005260:Female; D053686:Fetal Stem Cells / Q000166:cytology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D014157:Transcription Factors / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*
chemical_list: D000071616:CDX2 Transcription Factor; C487514:Cdx2 protein, mouse; D014157:Transcription Factors