Target-Induced Transcriptional Control of Dendritic Patterning and Connectivity in Motor Neurons by the ETS Gene Pea3

The apposition of axon terminals and dendrites is critical for the control of neuronal activation, but how distinct neuronal subpopulations establish selective dendrite patterns and acquire specific presynaptic inputs remains unclear. Spinal motor neuron (MN) pools project to specific target muscles and are activated by selective synaptic inputs from group Ia proprioceptive afferents (IaPAs). Here, we show that MN pools with radially projecting dendrites respond to sensory stimulation with monosynaptic latency and are strikingly different from MN pools with dendrites that avoid the central gray matter, which are only activated through indirect connections. We provide genetic evidence that the induction of the ETS transcription factor Pea3 by GDNF is essential in two cervical MN pools to control dendrite patterning and selectivity of IaPA connectivity. These findings suggest that target-induced transcriptional programs control MN dendrite orientation and play a crucial role in the establishment of sensory-motor connections in the spinal cord.