Proteome analysis of the dystrophin-deficient MDX diaphragm reveals a drastic increase in the heat shock protein cvHSP

Duchenne muscular dystrophy is the most commonly inherited neuromuscular disorder in humans. Although the primary genetic deficiency of dystrophin in X‐linked muscular dystrophy is established, it is not well‐known how pathophysiological events trigger the actual fibre degeneration. We have therefore performed a DIGE analysis of normal diaphragm muscle versus the severely affected x‐linked muscular dystrophy (MDX) diaphragm, which represents an established animal model of dystrophinopathy. Out of 2398 detectable 2‐D protein spots, 35 proteins showed a drastic differential expression pattern, with 21 proteins being decreased, including Fbxo11‐protein, adenylate kinase, β‐haemoglobin and dihydrolipoamide dehydrogenase, and 14 proteins being increased, including cvHSP, aldehyde reductase, desmin, vimentin, chaperonin, cardiac and muscle myosin heavy chain. This suggests that lack of sarcolemmal integrity triggers a generally perturbed protein expression pattern in dystrophin‐deficient fibres. However, the most significant finding was the dramatic increase in the small heat shock protein cvHSP, which was confirmed by 2‐D immunoblotting. Confocal fluorescence microscopy revealed elevated levels of cvHSP in MDX fibres. An immunoblotting survey of other key heat shock proteins showed a differential expression pattern in MDX diaphragm. Stress response appears to be an important cellular mechanism in dystrophic muscle and may be exploitable as a new approach to counteract muscle degeneration.