ADENOVIRAL VECTOR-MEDIATED EXPRESSION OF B-50 GAP-43 INDUCES ALTERATIONS IN THE MEMBRANE ORGANIZATION OF OLFACTORY AXON TERMINALS IN-VIVO/

B-50/GAP-43 is an intraneuronal membrane-associated growth cone protei n with an important role in axonal growth and regeneration. By using a denoviral vector-directed expression of B-50/GAP-43 we studied the mor phogenic action of B-50/GAP-43 in mature primary olfactory neurons tha t have established functional synaptic connections. B-50/GAP-43 induce d gradual alterations in the morphology of olfactory synapses. In the first days after overexpression, small protrusions originating from th e preterminal axon shaft and from the actual synaptic bouton were form ed. With time the progressive formation of multiple ultraterminal bran ches resulted in axonal labyrinths composed of tightly packed sheaths of neuronal membrane. Thus, B-50/GAP-43 is a protein that can promote neuronal membrane expansion at synaptic boutons. This function of B-50 /GAP-43 suggests that this protein may subserve an important role in o ngoing structural synaptic plasticity in adult neurons and in neuronal membrane repair after injury to synaptic fields.