A critical affinity window for IgSF proteins DIP-α and Dpr10 is required for proper motor neuron arborization

For neurons to establish the correct connections in animal nervous systems, interactions between cell adhesion molecules (CAMs), expressed presynaptically and postsynaptically, are thought to guide neurons to their targets. Here, we assess the role that affinity between two cognate CAMs-DIP-α and Dpr10-plays in establishing the leg neuromuscular system in Drosophila If affinity decreases or, surprisingly, increases past certain thresholds, motor neuron (MN) terminal branches fail to be maintained. Live imaging during development shows that when affinities are aberrant, MN filopodia are unable to productively engage their muscle targets. Thus, CAM affinities are tuned to achieve proper neuronal morphology.