Balancing competing effects of tissue growth and cytoskeletal regulation during Drosophila wing disc development

Cytoskeletal structure and force generation within cells must be carefully regulated as the developing organ grows to reach a final size and shape. However, how the complex regulation of multiple features of tissue architecture is simultaneously coordinated remains poorly understood. Through iterations between experiments and novel computational multi-scale model simulations, we investigate the combined regulation of cytoskeletal regulation and proliferation in the growing wing imaginal disc. First, we found through experiments and calibrated model simulations that the local curvature and nuclear positioning of cells in the growing wing disc are defined by patterning of nested spatial domains of peaks in apical and basal contractility. Additionally, predictions from model simulations that incorporate a mechanistic description of interkinetic nuclear migration demonstrate that cell proliferation increases the local basal curvature of the wing disc. This is confirmed experimentally as basal curvature increases when growth and proliferation are increased through insulin signaling. In surprising contrast, we experimentally found that Decapentaplegic (Dpp), the key morphogen involved in both growth control and patterning of the anterior-posterior axis, counteracts increases in tissue bending due to cell proliferation via a combined mechanism that balances the competing impacts of both proliferation and patterning of cell contractility. Overall, the high conservation of these regulatory interactions suggests an important balancing mechanism through dual regulation of proliferation and cytoskeleton to meet the multiple criteria defining tissue morphogenesis.