title: The primitive endoderm segregates from the epiblast in β1 integrin-deficient early mouse embryos.
abstract: We analyzed the mechanism of developmental failure in implanted β1 integrin-null blastocysts and found that primitive endoderm cells are present but segregate away from, instead of forming an epithelial layer covering, the inner cell mass. This cell segregation phenotype was also reproduced in β1 integrin-null embryoid bodies, in which primitive endoderm cells segregated and appeared as miniature aggregates detached from the core spheroids, and a primitive endoderm layer failed to form on the surface. Restricted β1 integrin gene deletion in embryos using Ttr-Cre or Sox2-Cre indicated that the loss of integrin function in the cells of the inner core rather than the outer layer is responsible for the failure to form a primitive endoderm layer. We conclude that β1 integrin is essential for the attachment of the primitive endoderm layer to the epiblast during the formation of a basement membrane, a process concurrent with the transition from cadherin- to integrin-mediated cell adhesion.
authors.affiliation: Department of Cell Biology, University of Miami School of Medicine, Miami, Florida, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Moore
authors.forename: Wensi
authors.initials: W
authors.lastname: Tao
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Smith
authors.forename: Xiang-Xi
authors.initials: XX
authors.lastname: Xu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001485:Basement Membrane / Q000196:embryology / Q000378:metabolism; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism*; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D002478:Cells, Cultured; D010064:Embryo Implantation; D058732:Embryoid Bodies / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D004707:Endoderm / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D005260:Female; D005855:Germ Layers / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D011247:Pregnancy
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D051017:Apoptosis Regulatory Proteins; D015820:Cadherins; C478773:Dab2 protein, mouse; D019012:Integrin beta1; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse