Résumé
A fundamental aspect of morphogenesis is the capacity of cells to actively exchange neighbors, which crucially requires remodeling of existing cadherin adhesive contacts. We investigate this process using Xenopus prechordal mesoderm as a model of a mesenchymal tissue, where cell-cell rearrangements are powered by differential migration. Using a reductionist approach, we unveil two concurrent mechanisms. Most cadherins are removed via "peeling," i.e., disruption of the trans bonds and lateral diffusion out of the contact. In parallel, a remnant of cadherins concentrates at the contact, which is resolved by tearing the cytoplasmic link with the cytoskeleton. Myosin is recruited peripheral to the contact, facilitating contact rupture. Manipulating cortical tension indicates that the balance between peeling and condensation mechanisms is sensitive to the magnitude and orientation of forces applied on the contact. This study unravels a new modality of cell contact dynamics likely to be widely relevant for mesenchymal tissues.