RAT OLFACTORY NEURONS CAN UTILIZE THE ENDOGENOUS LECTIN, L-14, IN A NOVEL ADHESION MECHANISM

L-14 is a divalent, lactosamine-binding lectin expressed in many verte brate tissues. In the rat nervous system, L-14 expression has been obs erved previously in restricted neuronal subsets within the dorsal root ganglia and spinal cord. In this study we report that L-14 is express ed by nonneuronal cells in the rat olfactory nerve. We demonstrate tha t L-14 binds and co-localizes with two ligands in the rat olfactory sy stem: a beta-lactosamine-containing glycolipid, and a putative member of the laminin family. The former is expressed on the surfaces of nasc ent olfactory axons originating from neuron cell bodies in the olfacto ry epithelium. The latter is present in the extracellular matrix of th e axonal path leading to synaptic targets in the olfactory bulb. In vi tro, we find that recombinant L-14 promotes primary olfactory neuron a dhesion to two laminin family members, and promotes intercellular adhe sion. Both activities are dose-dependent, and are independent of integ rinmediated mechanisms. We have thus found that L-14 can serve two dis tinct adhesive functions in vitro, and propose that L-14 in vivo can p romote olfactory axon fasciculation by crosslinking adjacent axons and promote axonal adhesion to the extracellular matrix.