Differential perturbations in the morphogenesis of anterior structures induced by overexpression of truncated XB- and N-cadherins in Xenopus embryos.
Cadherins, a family of Ca-dependent adhesion molecules, have been proposed to act as regulators of morphogenetic processes and to be major effectors in the maintenance of tissue integrity. In this study, we have compared the effects of the expression of two truncated cadherins during early neurogenesis in Xenopus laevis. mRNA encoding deleted forms of XB- and N-cadherin lacking most of the extracellular domain were injected into the four animal dorsal blastomeres of 32-cell stage Xenopus embryos. These truncated cadherins altered the cohesion of cells derived from the injected blastomeres and induced morphogenetic defects in the anterior neural tissue to which they chiefly contributed. Truncated XB-cadherin was more efficient than N-cadherin in inducing these perturbations. Moreover, the coexpression of both truncated cadherins had additive perturbation effects on neural development. The two truncated cadherins can interact with the three known catenins, but with distinct affinities. These results suggest that the adhesive signal mediated by cadherins can be perturbed by overexpressing their cytoplasmic domains by competing with different affinity with catenins and/or a common anchor structure. Therefore, the correct regulation of cadherin function through the cytoplasmic domain appears to be a crucial step in the formation of the neural tissue.
Dufour
S
S
Laboratoire de Physiopathologie du Développement du Centre National de la Recherche Scientifique URA 1337, Ecole Normale Supérieure, Paris, France.
Saint-Jeannet
J P
JP
Broders
F
F
Wedlich
D
D
Thiery
J P
JP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001757:Blastomeres / Q000166:cytology* / Q000378:metabolism; D015820:Cadherins / Q000235:genetics / Q000502:physiology*; D002448:Cell Adhesion; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015870:Gene Expression; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009420:Nervous System / Q000196:embryology*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D017384:Sequence Deletion; D015534:Trans-Activators; D029867:Xenopus Proteins; D014982:Xenopus laevis; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; D015820:Cadherins; D003598:Cytoskeletal Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D029867:Xenopus Proteins; D051176:beta Catenin