Temporal transcription factors determine circuit membership by permanently altering motor neuron-to-muscle synaptic partnerships

How circuit wiring is specified is a key question in developmental neurobiology. Previously, using the Drosophila motor system as a model, Meng and colleagues found the classic temporal transcription factor Hunchback acts in NB7-1 neuronal stem cells to control the number of NB7-1 neuronal progeny form functional synapses on dorsal muscles (Meng et al., 2019). However, it is unknown to what extent control of motor neuron-to-muscle synaptic partnerships is a general feature of temporal transcription factors. In a new paper published in the eLife journal, Meng, a CMB graduate student, and colleagues in the Heckscher and Carrillo labs perform additional temporal transcription factor manipulations—prolonging expression of Hunchback in NB3-1, as well as precociously expressing Pdm and Castor in NB7-1. They use confocal microscopy, calcium imaging, and electrophysiology to show that in every manipulation there are permanent alterations in neuromuscular synaptic partnerships.