Regeneration in sarcoglycanopathies: expression studies of sarcoglycans and other muscle proteins

We have studied the immunohistochemical expression of 14 different muscle p roteins of the basal lamina, sarcolemma and cytoskeleton in primary sarcogl ycanopathies (13 cases) and compared it with Duchenne dystrophy (6 cases) a nd myositis (5 cases). Sarcolemmal proteins (i.e. 4 sarcoglycans, beta-dyst roglycan, dystrophin, beta-spectrin) were reduced both in sarcoglycanopathi es and Duchenne dystrophy, because of structural and functional impairment of the plasma membrane. Sarcolemmal proteins are poorly expressed in regene rating fibers of all muscle disorders, due to a developmental delay or to a n abnormal assembly. Laminins (alpha 2 and beta chains) were preserved in a ll cases while utrophin was expressed in Duchenne muscle but not in sarcogl ycanopathies. Regenerating fibers were studied with different markers (i.e. fetal myosin, desmin, vimentin, laminin alpha 1). Fetal myosin positive fi bers las well as desmin and laminin alpha 1), were significantly higher in Duchenne dystrophy (25%) than in age-matched sarcoglycanopathies (7%). Vime ntin, a marker of early regeneration, was expressed at higher level in sarc oglycanopathies than in Duchenne dystrophy, suggesting in the former a lowe r extent of regeneration or a shorter regeneration cycle. (C) 1999 Elsevier Science B.V. All rights reserved.