Neurocrescin: A novel neurite-outgrowth factor secreted by muscle after denervation

REGENERATION Of injured axons at neuromuscular junctions has been assumed to be regulated by extracellular factors that promote neurite outgrowth. We report here the cloning of a novel neurite outgrowth factor, designated neurocrescin, from chick denervated skeletal muscle. A recombinant neurocrescin promoted neurite outgrowth from cultured neurons of spinal cord and telencephalon of chick embryo. It was expressed predominantly in neural tissue and muscle, and was secreted extracellularly after intramolecular cleavage. This truncated form was detected in denervated muscle but not in innervated muscle. Thus, neurocrescin appears to be a novel neurite outgrowth factor that is secreted in an activity-dependent fashion. A highly homologous counterpart was also cloned from mouse brain.