Cell-Fibronectin Interactions Propel Vertebrate Trunk Elongation via Tissue Mechanics

During embryonic development and tissue homeostasis, cells produce and remodel the extracellular matrix (ECM). The ECM maintains tissue integrity and can serve as a substrate for cell migration. Integrin alpha 5 (Itg alpha 5) and alpha V (Itg alpha V) are the alpha subunits of the integrins most responsible for both cell adhesion to the ECM protein fibronectin (FN) and FN matrix fibrillogenesis [1, 2]. We perform a systems-level analysis of cell motion in the zebrafish tail bud during trunk elongation in the presence and absence of normal cell-FN interactions. Itg alpha 5 and Itg alpha V have well-described roles in cell migration in vitro. However, we find that concomitant loss of itg alpha 5 and itg alpha V leads to a trunk elongation defect without substantive alteration of cell migration. Tissue-specific transgenic rescue experiments suggest that the FN matrix on the surface of the paraxial mesoderm is required for body elongation via its role in defining tissue mechanics and intertissue adhesion.