The Wnt receptor Ryk is required for Wnt5a-mediated axon guidance on the contralateral side of the corpus callosum

Abstract

Ryk (receptor related to tyrosine kinase) has been shown to be a novel Wnt receptor in both Caenorhabditis elegans and Drosophila melanogaster. Recently, Ryk-Wnt interactions were shown to guide corticospinal axons down the embryonic mouse spinal cord. Here we show that, in Ryk-deficient mice, cortical axons project aberrantly across the major forebrain commissure, the corpus callosum. Many mouse mutants have been described in which loss-of-function mutations result in the inability of callosal axons to cross the midline, thereby forming Probst bundles on the ipsilateral side. In contrast, loss of Ryk does not interfere with the ability of callosal axons to cross the midline but impedes thei..