Axon patterning requires DN-cadherin, a novel neuronal adhesion receptor, in the Drosophila embryonic CNS.

We identified DN-cadherin, a novel Drosophila cadherin that is expressed in axons and in the mesoderm. Although DN-cadherin has diverged from vertebrate classic cadherins in terms of its extracellular structure, it still can form a complex with catenins and induce cell aggregation, as do the vertebrate molecules. Loss-of-function mutations of the gene resulted in either embryonic lethality or uncoordinated locomotion of adults. In the central nervous system of null mutant embryos, subsets of ipsilateral axons displayed a variety of aberrant trajectories including failure of position shifts, defective bundling, and errors in directional migration of growth cones. These results suggest that processes of axon patterning critically depend on DN-cadherin-mediated axon-axon interactions.