Synthesis and Secretion of a High Molecular Weight form of Nerve Growth Factor by Skeletal Muscle Cells in Culture

Rat skeletal muscle cells and a cloned myogenic cell line synthesize and secrete in culture a molecule that is immunologically and biologically indistinguishable from the active form of nerve growth factor (NGF) from mouse submandibular gland. This protein can be detected in medium conditioned by muscle cells both before and after fusion and in the soluble fraction of muscle cell homogenates. Chromatographic data also reveal that the molecular properties of muscle cell NGF differ from those of the growth factor purified from mouse submandibular glands. Muscle cell NGF has a molecular weight between 140,000 and 160,000, whereas purified mouse gland NGF has a molecular weight of 26,000. The biologic function of muscle cell NGF is not known, although it could be that it plays some role relating to the association of nerves and muscle in vivo.