Signaling-dependent refinement of cell fate choice during tissue remodeling in Drosophila pupal wings

How cell fate decisions and tissue remodeling are coordinated to establish precise and robust patterns is a fundamental question in developmental biology. Here, we investigate this interplay during the refinement of Drosophila wing veins. We show by live imaging that vein refinement is driven initially by local tissue deformation, followed by cell fate adjustments orchestrated by a signaling network involving Notch, EGFR, and Dpp. Dynamic tracking of signaling reporter activity uncovers a wave of Notch signaling that converts wide crude proveins into thin stereotypical veins. Perturbing large-scale convergence and extension does not affect vein refinement, and optogenetically induced veins refine irrespective of their orientation, demonstrating that the signaling network suffices for refinement, independently of large-scale tissue flows. A minimal biophysical description recapitulates the signaling network's ability to coordinate vein refinement in various experimental situations. Our results illustrate how cell fate decisions are updated for robust patterning in a remodeling tissue.