Distinct roles for secreted semaphorin signaling in spinal motor axon guidance

Andrea B. Huber, Artur Kania, Tracy S. Tran, Chenghua Gu, Natalia De Marco Garcia, Ivo Lieberam, Dontais Johnson, Thomas M. Jessell, David D. Ginty, Alex L. Kolodkin

Research output: Contribution to journalArticlepeer-review

178 Scopus citations

Abstract

Neuropilins, secreted semaphorin coreceptors, are expressed in discrete populations of spinal motor neurons, suggesting they provide critical guidance information for the establishment of functional motor circuitry. We show here that motor axon growth and guidance are impaired in the absence of Sema3A-Npn-1 signaling. Motor axons enter the limb precociously, showing that Sema3A controls the timing of motor axon in-growth to the limb. Lateral motor column (LMC) motor axons within spinal nerves are defasciculated as they grow toward the limb and converge in the plexus region. Medial and lateral LMC motor axons show dorso-ventral guidance defects in the forelimb. In contrast, Sema3F-Npn-2 signaling guides the axons of a medial subset of LMC neurons to the ventral limb, but plays no major role in regulating their fasciculation. Thus, Sema3A-Npn-1 and Sema3F-Npn-2 signaling control distinct steps of motor axon growth and guidance during the formation of spinal motor connections.

Original languageEnglish (US)
Pages (from-to)949-964
Number of pages16
JournalNeuron
Volume48
Issue number6
DOIs
StatePublished - Dec 22 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

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