title: aPKC, Crumbs3 and Lgl2 control apicobasal polarity in early vertebrate development.
abstract: In early vertebrate development, apicobasally polarised blastomeres divide to produce inner non-polarised cells and outer polarised cells that follow different fates. How the polarity of these early blastomeres is established is not known. We have examined the role of Crumbs3, Lgl2 and the apical aPKC in the polarisation of frog blastomeres. Lgl2 localises to the basolateral membrane of blastomeres, while Crumbs3 localises to the apical and basolateral membranes. Overexpression aPKC and Crumbs3 expands the apical domain at the expense of the basolateral and repositions tight junctions in the new apical-basolateral interface. Loss of aPKC function causes loss of apical markers and redirects basolateral markers ectopically to the apical membrane. Cell polarity and tight junctions, but not cell adhesion, are lost and outer polarised cells become inner-like apolar cells. Overexpression of Xenopus Lgl2 phenocopies the aPKC knockout, suggesting that Lgl2 and aPKC act antagonistically. This was confirmed by showing that aPKC and Lgl2 can inhibit the localisation of each other and that Lgl2 rescues the apicalisation caused by aPKC. We conclude that an instrumental antagonistic interaction between aPKC and Lgl2 defines apicobasal polarity in early vertebrate development.
authors.affiliation: Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QR, UK.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Chalmers
authors.forename: Michael
authors.initials: M
authors.lastname: Pambos
authors.forename: Julia
authors.initials: J
authors.lastname: Mason
authors.forename: Stephanie
authors.initials: S
authors.lastname: Lang
authors.forename: Chris
authors.initials: C
authors.lastname: Wylie
authors.forename: Nancy
authors.initials: N
authors.lastname: Papalopulu
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D019070:Cell Lineage; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000378:metabolism; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008969:Molecular Sequence Data; D011493:Protein Kinase C / Q000502:physiology*; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus; D028961:beta Karyopherins / Q000502:physiology*
chemical_list: C472002:CRB3 protein, human; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D028961:beta Karyopherins; C424163:late gestation lung 2 karyopherin; D049452:Green Fluorescent Proteins; D012313:RNA; D004247:DNA; C115015:PKC-3 protein; D011493:Protein Kinase C