title: ZO-1 and ZO-2 are required for extra-embryonic endoderm integrity, primitive ectoderm survival and normal cavitation in embryoid bodies derived from mouse embryonic stem cells.
abstract: The Zonula Occludens proteins ZO-1 and ZO-2 are cell-cell junction-associated adaptor proteins that are essential for the structural and regulatory functions of tight junctions in epithelial cells and their absence leads to early embryonic lethality in mouse models. Here, we use the embryoid body, an in vitro peri-implantation mouse embryogenesis model, to elucidate and dissect the roles ZO-1 and ZO-2 play in epithelial morphogenesis and de novo tight junction assembly. Through the generation of individual or combined ZO-1 and ZO-2 null embryoid bodies, we show that their dual deletion prevents tight junction formation, resulting in the disorganization and compromised barrier function of embryoid body epithelial layers. The disorganization is associated with poor microvilli development, fragmented basement membrane deposition and impaired cavity formation, all of which are key epithelial tissue morphogenetic processes. Expression of Podocalyxin, which positively regulates the formation of microvilli and the apical membrane, is repressed in embryoid bodies lacking both ZO-1 and ZO-2 and this correlates with an aberrant submembranous localization of Ezrin. The null embryoid bodies thus give an insight into how the two ZO proteins influence early mouse embryogenesis and possible mechanisms underlying the embryonic lethal phenotype.
authors.affiliation: Epithelial Cell Biology Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science Technology and Research (A*STAR), Singapore, Singapore.
authors.forename: Dominic C Y
authors.initials: DC
authors.lastname: Phua
authors.affiliation: Epithelial Cell Biology Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science Technology and Research (A*STAR), Singapore, Singapore.
authors.forename: Jianliang
authors.initials: J
authors.lastname: Xu
authors.affiliation: Epithelial Cell Biology Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science Technology and Research (A*STAR), Singapore, Singapore.
authors.forename: Safiah Mohamed
authors.initials: SM
authors.lastname: Ali
authors.affiliation: Epithelial Cell Biology Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science Technology and Research (A*STAR), Singapore, Singapore; IMB-IMCB Joint Electron Microscopy Suite, Agency for Science Technology and Research (A*STAR), Singapore, Singapore.
authors.forename: Adrian
authors.initials: A
authors.lastname: Boey
authors.affiliation: Epithelial Cell Biology Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science Technology and Research (A*STAR), Singapore, Singapore; IMB-IMCB Joint Electron Microscopy Suite, Agency for Science Technology and Research (A*STAR), Singapore, Singapore.
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Gounko
authors.affiliation: Epithelial Cell Biology Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science Technology and Research (A*STAR), Singapore, Singapore; Department of Physiology, National University of Singapore and Singapore Eye Research Institute (SERI), Singapore, Singapore.
authors.forename: Walter
authors.initials: W
authors.lastname: Hunziker
mesh_terms: D000818:Animals; D004475:Ectoderm / Q000166:cytology / Q000378:metabolism*; D058732:Embryoid Bodies / Q000166:cytology / Q000378:metabolism*; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D004707:Endoderm / Q000166:cytology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D018345:Mice, Knockout; D011506:Proteins / Q000378:metabolism; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism*; D062827:Zonula Occludens-2 Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D011506:Proteins; C569043:Tjp1 protein, mouse; C569047:Tjp2 protein, mouse; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; C477528:podocan protein, mouse