title: E-cadherin is required for gastrulation cell movements in zebrafish.
abstract: E-cadherin is a member of the classical cadherin family and is known to be involved in cell-cell adhesion and the adhesion-dependent morphogenesis of various tissues. We isolated a zebrafish mutant (cdh1(rk3)) that has a mutation in the e-cadherin/cdh1 gene. The mutation rk3 is a hypomorphic allele, and the homozygous mutant embryos displayed variable phenotypes in gastrulation and tissue morphogenesis. The most severely affected embryos displayed epiboly delay, decreased convergence and extension movements, and the dissociation of cells from the embryos, resulting in early embryonic lethality. The less severely affected embryos survived through the pharyngula stage and showed flattened anterior neural tissue, abnormal positioning and morphology of the hatching gland, scattered trigeminal ganglia, and aberrant axon bundles from the trigeminal ganglia. Maternal-zygotic cdh1(rk3) embryos displayed epiboly arrest during gastrulation, in which the enveloping layer (EVL) and the yolk syncytial layer but not the deep cells (DC) completed epiboly. A similar phenotype was observed in embryos that received antisense morpholino oligonucleotides (cdh1MO) against E-cadherin, and in zebrafish epiboly mutants. Complementation analysis with the zebrafish epiboly mutant weg suggested that cdh1(rk3) is allelic to half baked/weg. Immunohistochemistry with an anti-beta-catenin antibody and electron microscopy revealed that adhesion between the DCs and the EVL was mostly disrupted but the adhesion between DCs was relatively unaffected in the MZcdh1(rk3) mutant and cdh1 morphant embryos. These data suggest that E-cadherin-mediated cell adhesion between the DC and EVL plays a role in the epiboly movement in zebrafish.
authors.affiliation: Laboratory for Vertebrate Axis Formation, Center for Developmental Biology, RIKEN, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Taijiro
authors.initials: T
authors.lastname: Yabe
authors.forename: Osamu
authors.initials: O
authors.lastname: Muraoka
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Yonemura
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Aramaki
authors.forename: Kohei
authors.initials: K
authors.lastname: Hatta
authors.forename: Young-Ki
authors.initials: YK
authors.lastname: Bae
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nojima
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hibi
mesh_terms: D000483:Alleles; D000818:Animals; D001483:Base Sequence; D001896:Boron Compounds / Q000494:pharmacology; D015820:Cadherins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002448:Cell Adhesion; D002465:Cell Movement; D005091:Exons; D005775:Gastrula / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007211:Indoles / Q000494:pharmacology; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009068:Movement; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D009841:Oligonucleotides / Q000494:pharmacology; D010641:Phenotype; D012689:Sequence Homology, Nucleic Acid; D013696:Temperature; D015027:Zebrafish; D015053:Zygote
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D015820:Cadherins; D007211:Indoles; D009841:Oligonucleotides; C007293:DAPI