Sciatin: Purification, Characterization, Localization and Biological Properties of a Myotrophic Protein from Sciatic Nerves

Abstract

We have isolated and purified a biologically-active protein from chicken sciatic nerves which exerts trophic effects on cultured muscle. This myotrophic protein, referred to as sciatin, is an acidic glycoprotein with a native MW of 86,400. Sciatin promotes the morphological maturation and maintenance of aneural chick muscle cells, and increases protein synthesis and acetylcholine receptors in these cells in the absence of innervation. Immunocytochemical studies at the light microscopic level reveal that sciatin is localized in the perikarya of spinal cord neurons and the axoplasm of sciatic nerves of chickens. Immunoprecipitation studies indicate that sciatin is the biologically-active component of chick embryo extract which is a required component of culture medium for avian myogenesis in vitro and that sciatin is essential for the initial differentiation of chick myogenic cells. Preliminary studies suggest that sciatin is transported by axonal flow in chicken sciatic nerves and released from chicken nerve-muscle preparations by electrical stimulation. Finally, recent studies indicate that sciatin is highly enriched in chicken sciatic nerves and is also present in chicken serum.