Complementary expression and regulation of cadherins 6 and 11 during specific steps of motoneuron differentiation.

Cadherins constitute one of the major classes of adhesion receptors participating in the architectural organization of embryonic tissues. We previously identified type II cadherins 6 and 11, whose mRNA expression was tightly regulated during mouse neuromuscular development. Here we determine the regulation of expression and the localization of the corresponding proteins in relation to spinal neuron differentiation and peripheral nerve outgrowth. Cadherin-11 expression initially appeared in motor columns before extending to the whole spinal cord, dorsal root ganglia, and sensory-motor peripheral nerves. Then, its expression decreased in nervous tissues and became predominant in mesenchymes. Cadherin-6 was exclusively expressed in floor and roof plates, motor columns, and motor peripheral nerves, including motor axons and Schwann cell precursors. Compared to cadherin-11, its expression in motor columns was delayed and restricted to certain subpopulations of motoneurons. These results strongly implicate cadherins 6 and 11 in the control of spinal motoneuron differentiation and segregation and in axoaxonal, axoglial, and glio-glial interactions during sensory-motor nerve progression.