Physical and functional cell-matrix uncoupling in a developing tissue under tension

Abstract

Tissuemechanics playacrucial role in organ development.They relyon the properties of cells and the extracellularmatrix (ECM), but the relative physical contribution of cells and ECM to morphogenesis is poorly understood. Here, we have analyzed the behavior of the peripodial epithelium (PE) of the Drosophila leg disc in the light of the dynamics of its cellular and ECM components. The PE undergoes successive changes during leg development, including elongation, opening and removal to free the leg. During elongation, we found that the ECM and cell layer are progressively uncoupled. Concomitantly, the tension, mainly borne by the ECM at first, builds up in the cellmonolayer. Then, each layer of the peripodial epithelium is removed by an independent mechanism: While the ECM layer withdraws following local proteolysis, cellular monolayer withdrawal is independent of ECM degradation and is driven by myosin II-dependent contraction. These results reveal a surprising physical and functional cell-matrix uncoupling in amonolayer epithelium under tension during development. This article has an associated ‘The people behind the papers’ interview.