Adhesion to a common ECM mediates interdependence in tissue morphogenesis in Drosophila.

Organ functionality requires the precise coordination of diverse tissues during development. Halfway through Drosophila embryogenesis, two lateral epidermal sheets stretch to fuse at the dorsal midline; concomitant with this, the main tubes of the respiratory system also shift dorsally. Here, we demonstrate that these processes occur simultaneously and are coordinated by the adhesion of the epidermal sheets and a subset of cells of the tracheal trunks to a common extracellular matrix (ECM) that separates them. We also show that during dorsal closure, tracheal trunk cells extend protrusions towards the ECM underneath the epidermis. These protrusions are under tension, suggesting that they have a mechanical function. Additionally, perturbing adhesion between tracheal cells and the epidermis affects the development of both tissues. Altogether, our findings uncover a mechanism used for tissue coordination during development, one that is based on tissue adhesion towards a common ECM capable of transmitting mechanical forces across the embryo.