Changes in the pattern of adherens junction-associated beta-catenin accompany morphogenesis in the sea urchin embryo.
beta-Catenin was originally identified biochemically as a protein that binds E-cadherin in cultured cells and that interaction was later shown to be essential for cadherin function. Independently, armadillo, the beta-catenin homolog in Drosophila melanogaster, was identified as a segment polarity gene necessary for the transduction of wingless (Wnt) signals during embryonic and larval development. Recently, several investigations have also shown that beta-catenin plays a critical role in axial patterning of early Xenopus, zebrafish, and mouse embryos. In these systems, the localization of beta-catenin to the plasma membrane, cytosol, and nucleus is predictive of its role in cell adhesion and signaling. In order to examine the potential role of beta-catenin in regulating cell adhesion during embryogenesis, we cloned beta-catenin in the sea urchin Lytechinus variegatus and characterized its subcellular distribution in cells undergoing morphogenetic movements. Indicative of a role in the establishment and maintenance of cell adhesion, beta-catenin is associated with lateral cell-cell contacts and accumulates at adherens junctions from cleavage stages onward. At gastrulation, changes in junctional beta-catenin localization accompany several morphogenetic events. The epithelial-mesenchymal conversion that characterizes the ingression of both primary and secondary mesenchyme cells coincides with a rapid and dramatic loss of adherens junction-associated beta-catenin. In addition, epithelial cells in the archenteron display a significant decrease in adherens junction-associated beta-catenin levels as they undergo convergent-extension movements. These data are consistent with a role for beta-catenin in regulating cell adhesion and adherens junction function during gastrulation in the sea urchin embryo.
Miller
J R
JR
Developmental, Cellular and Molecular Biology Group, Duke University, Durham, North Carolina 27708, USA. shinichi@nibb.ac.jp
McClay
D R
DR
D000595:Amino Acid Sequence; D000818:Animals; D051186:Armadillo Domain Proteins; D002448:Cell Adhesion / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology; D004848:Epithelium / Q000196:embryology; D005775:Gastrula / Q000166:cytology / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics; D007365:Intercellular Junctions / Q000378:metabolism*; D008648:Mesoderm / Q000166:cytology; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009068:Movement; D012617:Sea Urchins / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000235:genetics; D051178:alpha Catenin; D051176:beta Catenin
C495305:ARM protein, Drosophila; D051186:Armadillo Domain Proteins; C495266:CTNNB1 protein, Xenopus; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D029867:Xenopus Proteins; D051178:alpha Catenin; D051176:beta Catenin