NEUROCRESCIN - A NOVEL NEURITE-OUTGROWTH FACTOR SECRETED BY MUSCLE AFTER DENERVATION

REGENERATION Of injured axons at neuromuscular junctions has been assu med to be regulated by extracellular factors that promote neurite outg rowth. We report here the cloning of a novel neurite outgrowth factor, designated neurocrescin, from chick denervated skeletal muscle. A rec ombinant neurocrescin promoted neurite outgrowth from cultured neurons of spinal cord and telencephalon of chick embryo. It was expressed pr edominantly in neural tissue and muscle, and was secreted extracellula rly after intramolecular cleavage. This truncated form was detected in denervated muscle but not in innervated muscle. Thus, neurocrescin ap pears to be a novel neurite outgrowth factor that is secreted in an ac tivity-dependent fashion. A highly homologous counterpart was also clo ned from mouse brain.