A light and electron microscopic study of dystrophin localization at the mouse neuromuscular junction

Duchenne muscular dystrophy (DMD) is characterized by a lack of dystrophin expression. Dystrophin is a 420 Kd protein localized in the muscle sarcolemma that most likely provides stability to the muscle plasma membrane. Neuromuscular junctions (NMJs) were localized by revealing either the acetylcholine receptors (AChRs) with alpha-bungarotoxin coupled with cascade blue or by revealing desmin, a protein found in higher concentration at the NMJs using immunochemistry. An accumulation of dystrophin was observed in normal mice by immunoperoxidase labelling at NMJs identified with these markers. Dystrophin was pinpointed on the postjunctional folds of NMJs by electron microscopy and was more abundant on the postjunctional membrane than on the remaining muscle membrane. Our observations are similar to previous observations suggesting that dystrophin may interact with the AChRs.