title: Gene replacement reveals a specific role for E-cadherin in the formation of a functional trophectoderm.
abstract: During mammalian embryogenesis the trophectoderm represents the first epithelial structure formed. The cell adhesion molecule E-cadherin is ultimately necessary for the transition from compacted morula to the formation of the blastocyst to ensure correct establishment of adhesion junctions in the trophectoderm. Here, we analyzed to what extent E-cadherin confers unique adhesion and signaling properties in trophectoderm formation in vivo. Using a gene replacement approach, we introduced N-cadherin cDNA into the E-cadherin genomic locus. We show that the expression of N-cadherin driven from the E-cadherin locus reflects the expression pattern of endogenous E-cadherin. Heterozygous mice co-expressing E- and N-cadherin are vital and show normal embryonic development. Interestingly, N-cadherin homozygous mutant embryos phenocopy E-cadherin-null mutant embryos. Upon removal of the maternal E-cadherin, we demonstrate that N-cadherin is able to provide sufficient cellular adhesion to mediate morula compaction, but is insufficient for the subsequent formation of a fully polarized functional trophectoderm. When ES cells were isolated from N-cadherin homozygous mutant embryos and teratomas were produced, these ES cells differentiated into a large variety of tissue-like structures. Importantly, different epithelial-like structures expressing N-cadherin were formed, including respiratory epithelia, squamous epithelia with signs of keratinization and secretory epithelia with goblet cells. Thus, N-cadherin can maintain epithelia in differentiating ES cells, but not during the formation of the trophectoderm. Our results point to a specific and unique function for E-cadherin during mouse preimplantation development.
authors.affiliation: Max-Planck-Institut für Immunbiologie, Abteilung für Molekulare Embryologie, Stübeweg 51, D-79108 Freiburg, Germany.
authors.forename: Natalia G
authors.initials: NG
authors.lastname: Kan
authors.forename: Marc P
authors.initials: MP
authors.lastname: Stemmler
authors.forename: Dirk
authors.initials: D
authors.lastname: Junghans
authors.forename: Benoît
authors.initials: B
authors.lastname: Kanzler
authors.forename: Wilhelmine N
authors.initials: WN
authors.lastname: de Vries
authors.forename: Mara
authors.initials: M
authors.lastname: Dominis
authors.forename: Rolf
authors.initials: R
authors.lastname: Kemler
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000502:physiology*; D015820:Cadherins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D002448:Cell Adhesion; D002454:Cell Differentiation; D019070:Cell Lineage; D002478:Cells, Cultured; D003433:Crosses, Genetic; D004475:Ectoderm / Q000166:cytology / Q000502:physiology*; D004622:Embryo, Mammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018715:Microscopy, Video; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D015820:Cadherins; D001616:beta-Galactosidase