A Cell-Level Mechanobiological Model of Drosophila Dorsal Closure

Abstract

We report a model describing various stages of Drosophila dorsal closure. Inspired by experimental observations, we represent the amnioserosa by hexagonal cells that are coupled mechanically through the position of nodes and the elastic forces on the edges. Besides, each cell has radial spokes on which myosin motors can attach and exert contractile forces, the myosin dynamics itself being controlled by a signaling molecule. In the early phase, amnioserosa cells oscillate as a result of coupling among the chemical signaling, myosin activity and mechanical deformation of neighboring cells. Cross-correlation function of area variation of neighboring cells calculated based on our model predictions shows agreement with previous studies. In slow phase, we test two ‘ratcheting mechanisms' suggested by experiments: an internal ratchet by the myosin condensates in the apical medial surface and an external one by the supracellular actin cables encircling the amnioserosa. Our model predictions suggest the former as the main contributor to cell and tissue reduction in this stage. In fast phase of dorsal closure, we gradually shrink the resting length of radial spokes to simulate the consistent tissue contraction.