TENASCIN-C EXPRESSION IN DYSTROPHIN-RELATED MUSCULAR-DYSTROPHY

The mdx mouse has a mutated dystrophin gene and is used as a model for the study of Duchenne muscular dystrophy (DMD). We investigated wheth er regenerating mdx skeletal muscle contains the extracellular matrix protein tenascin-C (TN-C), which is expressed in wound healing and ner ve regeneration. Prior to the initiation of muscle degeneration, both normal and mdx mice displayed similar weak staining for TN-C in skelet al muscle, but by 3 weeks of age the mice differed substantially. TN-C was undetectable in normal muscle except at the myotendinous junction , while in dystrophic muscle, TN-C was prominent in degenerating/regen erating areas, but absent from undegenerated muscle. With increasing a ge, TN-C staining declined around stable regenerated mdx myofibers. TN -C was also observed in muscle from dogs with muscular dystrophy and i n human boys with DMD. Therefore, in dystrophic muscle, TN-C expressio n may be stimulated by the degenerative process and remain upregulated unless the tissue undergoes successful regeneration. (C) 1996 John Wi ley & Sons, Inc.