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

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