Increased expression of cofilin in dystrophic chicken and mouse skeletal muscles.

A monoclonal antibody (McAb) specific for actin depolymerizing factor (ADF) was prepared. With this and previously prepared anti-cofilin McAb (MAB-22) and other antibodies, the expression of cofilin and ADF in the muscles of dystrophic (NH-413) chicken and dystrophic (C57BL/6J dy/dy) mice was compared with that in normal control animals by immunoblotting and immunocytochemical methods. Since cofilin expression is down-regulated during normal postnatal development of skeletal muscles [Abe et al. (1989) J. Biochem. 106, 696-702], cofilin was detected in the breast (pectoralis) muscle of normal adult chicken and the leg (femoris and tibialis anterior) muscles of normal mice only at a low level. ADF was not detectable in adult skeletal muscles. However, a significant increase of cofilin amount, but not of ADF amount, was observed in these muscles of the dystrophic animals, when the symptom of muscular dystrophy became evident. In order to localize cofilin in individual muscle fibers, serial cryosections of the dystrophic chicken muscle were examined with anti-cofilin antibody (MAB-22). The antibody stained cells of different size in the dystrophic muscle, indicating that cofilin expression was induced in the regenerating muscle cells as well as in the pre-existing myofibers. We suggest that cofilin is involved in disassembly or reorganization of actin in the dystrophic muscle.