A possible link between cell adhesion receptors, homeodomain proteins and neuronal identity.

The orderly arrangement of neuronal cell bodies and axonal projections generated during nervous system development requires precise spatio-temporal control of the expression and activity of cell adhesion receptors. Recent evidence suggests that homeobox genes, an important class of developmental control genes, many of which are preferentially expressed in developing nervous tissue, play prominent roles in the regulation of expression of these molecules. We have characterised two mouse homeobox genes, named Cux and Phox2, the products of which bind to and regulate the promoter of the Ncam gene in vitro. Its highly specific expression pattern suggests that Phox2, besides regulating Ncam, may be determinant of the noradrenergic phenotype.