The Bmp Gradient of the Zebrafish Gastrula Guides Migrating Lateral Cells by Regulating Cell-Cell Adhesion

C’est la suite de « Vertebrate Gastrulation: The BMP Sticker Shock« , en fait le papier qui a suscité le commentaire. On dirait que les mouvements cellulaires obéissent à la présence de « molécules » et de « gradients chimiques » plutôt qu’à « Un mouvement d’ensemble, quel que soient le contenu génétique. » [VF, 10-01-2007 à 11:52]

Results

  • The Bmp Gradient Determines the Direction of Convergence Movements
  • Slow Convergence Requires Bmp Signaling in the Environment and Is Independent of Noncanonical and Signaling
  • Bmp Signaling Can Affect Independently of
  • High Bmp Signaling Leads to an Uncoupling of Retraction and Cell Body Displacement
  • Bmp Signaling Negatively Regulates Ca2+/-Dependent Cell-Cell Adhesiveness In Vitro and In Vivo
  • Genetic Interaction of N-Cadherin and Bmp Signaling during Dorsal Convergence, but Not during
  • Locally Applied Ca2+-Chelators Can Replace Bmp Beads to Restore Directed Cell Migration in bmp2b Morphants

The Bmp Gradient of the Guides Migrating Lateral Cells by Regulating

Sophia von der Hardt, Jeroen Bakkers, Adi Inbal, Lara Carvalho, Lilianna Solnica-Krezel, Carl-Philipp Heisenberg and Matthias Hammerschmidt

Current Biology, Volume 17, Issue 6, 20 March 2007, Pages 475-487

Background
Bone morphogenetic proteins (s) are required for the specification of ventrolateral cell fates during and for proper convergence and , but the mechanisms underlying the latter role remained elusive.

Results
Via bead implantations, we show that the Bmp gradient determines the direction of during dorsal convergence in the zebrafish gastrula. This effect is independent of its role during dorsoventral patterning and of . However, it requires Bmp signal transduction through and to negatively regulate Ca2+/Cadherin-dependent cell-cell adhesiveness. In vivo, converging mesodermal cells form lamellipodia that attach to adjacent cells. Bmp signaling diminishes the Cadherin-dependent stability of such contact points, thereby abrogating subsequent cell displacement during lamellipodial retraction.

Conclusions
We propose that the ventral-to-dorsal Bmp gradient has an instructive role to establish a reverse gradient of cell-cell adhesiveness, thereby defining different migratory zones and directing lamellipodia-driven cell migrations during dorsal convergence in lateral regions of the zebrafish gastrula.

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