Embryonic dopaminergic neuron activity sustains lifelong locomotion in Drosophila

Locomotor skills arise early in life and are maintained throughout an animals lifespan, yet how this continuity is achieved despite major neural remodeling remains unclear. Using Drosophila, which undergoes complete metamorphosis, we show that the activity of embryonically established dopamine neurons (DANs) is essential for locomotion across all developmental stages and adulthood. Through stage-specific behavioral assays, optogenetics, in vivo brain imaging, and fluorescent neuronal tracking, we identify a subset of ventral nervous system (VNS) DANs that modulate locomotor function throughout life. Transcriptomic analyses reveal that they maintain expression of developmental transcription factors. Knocking down these factors, particularly Antp and Pdm2, in post-mitotic VNS DANs reduces neurite arborization and impairs adult locomotion. These findings uncover a previously overlooked function for embryonic DANs and suggest that stable locomotion during nervous system maturation relies on persistent developmental regulator expression coupled with structural remodeling.