Juxtaposition of CNR protocadherins and reelin expression in the developing spinal cord

The CNR (cadherin-related neuronal receptors) family of protocadherins is of great interest because of their potential roles as molecular tags in the formation of specific synaptic connections, and as receptors for reelin, during neuronal migration, and cell body positioning. In order to know more about potential functions of CNRs we have mapped their expression during mouse nervous system development and compared their expression with that of reelin and its intracellular effector Dab1 in several tissues. In spinal cord, CNRs and Dab1 are expressed in motoneurons, while reelin is located in adjacent cells. In the hindbrain, there is a differential expression of CNRs and Dab1 in various motor nuclei. In the retina and olfactory system, we observe CNR and reelin expression but not that of Dab1. These results provide new insights into the potential functions of CNRs and their possible integration in the reelin pathway during development.