The selectivity with which proprioceptive sensory neurons innervate their central and peripheral targets implies that they exhibit distinctions in muscle-type identity. The molecular correlates of proprioceptor identity and its origins remain largely unknown, however. In screens to define muscle-type proprioceptor character, we find all-or-none differences in gene expression for proprioceptors that control antagonistic muscles at a single hindlimb joint. Analysis of three of these genes, cadherin13 (cdh13), semaphorin5a (sema5a), and cartilage-acidic protein-1 (crtac1), reveals expression in proprioceptor subsets that supply muscle groups located at restricted dorsoventral and proximodistal domains of the limb. Genetically altering the dorsoventral character of the limb mesenchyme elicits a change in the profile of proprioceptor cdh13, sema5a, and crtac1 expression. These findings indicate that proprioceptors acquire aspects of their muscle-type identity in response to mesenchymal signals expressed in restricted proximodistal and dorsoventral domains of the developing limb.
Copyright © 2016 Elsevier Inc. All rights reserved.