Int. J. Dev. Biol. 46: 785 - 792 (2002)
© UPV/EHU Press

Type I cadherins are required for differentiation and coordinated rotation in Xenopus laevis somitogenesis.

Emiliana Giacomello, Jerome Vallin, Olivier Morali, Ivan S Coulter, Habib Boulekbache, Jean P Thiery and Florence Broders

Institut Curie, CNRS-UMR 144, Laboratoire de Morphogénèse et progression tumorale, Paris, France. giacomello@unisi.it

ABSTRACT In Xenopus laevis somitogenesis, somitic blocks undergo coordinated movements resulting in their detachment from the rest of the mesodermal ridge, followed by a 90 degrees rotation of the entire metamere. Here we investigated the function of type I cadherins in somitogenesis. Type I cadherins are Ca(2+)-dependent cell-cell adhesion molecules concentrated in the adherens junctions and highly expressed in the somitic tissue. We analyzed their role in somitogenesis by overexpressing either the intracellular (deltaE) and the extracellular (C-trunc) dominant-negative forms of cadherin. The resulting phenotype was a downward bend of the anterior-posterior axis in tadpole stage embryos. 12/101 antigen and X-Myo-D expression were altered. Microscopy revealed disorganization of the myotomes. Conversely, segmentation was conserved at the microscopic and molecular levels.