Characterization of Netrin-1, Neogenin and cUNC-5H3 expression during chick dorsal root ganglia development.

The molecular mechanisms that control the axon pathfinding of different subtypes of dorsal root ganglia (DRG) neurons are poorly understood. To address whether Netrin-1-Neogenin/UNC-5 signaling contributes to sensory axon pathfinding, we cloned chick UNC5 homolog 3 (cUNC-5H3) and characterized the spatial, cellular and temporal expression patterns of Netrin-1, Neogenin and cUNC-5H3 in cutaneous and proprioceptive DRG neurons. We have found that Netrin-1 is only expressed by late-arising cutaneous neurons. In contrast, cUNC-5H3 expression is restricted to proprioceptive neurons. Neogenin is expressed in all DRG neurons. Our results indicate that the pathfinding molecules, Netrin-1 and cUNC-5H3 are differentially expressed by early cutaneous and proprioceptive neurons.