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Synapse Formation in Monosynaptic Sensory–Motor Connections Is Regulated by Presynaptic Rho GTPase Cdc42
The Journal of Neuroscience
  • Fumiyasu Imai
  • David R. Ladle, Wright State University - Main Campus
  • Jennifer R. Leslie
  • Xin Duan
  • Tilat A. Rizvi
  • Georgianne M. Ciraolo
  • Yi Zheng
  • Yutaka Yoshida
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Spinal reflex circuit development requires the precise regulation of axon trajectories, synaptic specificity, and synapse formation. Of these three crucial steps, the molecular mechanisms underlying synapse formation between group Ia proprioceptive sensory neurons and motor neurons is the least understood. Here, we show that the Rho GTPase Cdc42 controls synapse formation in monosynaptic sensory–motor connections in presynaptic, but not postsynaptic, neurons. In mice lacking Cdc42 in presynaptic sensory neurons, proprioceptive sensory axons appropriately reach the ventral spinal cord, but significantly fewer synapses are formed with motor neurons compared with wild-type mice. Concordantly, electrophysiological analyses show diminished EPSP amplitudes in monosynaptic sensory–motor circuits in these mutants. Temporally targeted deletion of Cdc42 in sensory neurons after sensory–motor circuit establishment reveals that Cdc42 does not affect synaptic transmission. Furthermore, addition of the synaptic organizers, neuroligins, induces presynaptic differentiation of wild-type, but not Cdc42-deficient, proprioceptive sensory neurons in vitro. Together, our findings demonstrate that Cdc42 in presynaptic neurons is required for synapse formation in monosynaptic sensory–motor circuits.

Copyright © 2016 the authors. Licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) license.

Citation Information
Fumiyasu Imai, David R. Ladle, Jennifer R. Leslie, Xin Duan, et al.. "Synapse Formation in Monosynaptic Sensory–Motor Connections Is Regulated by Presynaptic Rho GTPase Cdc42" The Journal of Neuroscience Vol. 36 Iss. 21 (2016) p. 5724 - 5735 ISSN: 02706474
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