Syncoilin accumulation in two patients with desmin-related myopathy.

We have recently shown that syncoilin interacts with desmin in skeletal muscle and has a role in attaching and organising desmin filaments to the Z-lines. We have analysed patients with desmin accumulation and have found that syncoilin is both upregulated at the sarcolemma and aggregates with desmin indicating the presence of two distinct protein populations. Additional dystrophin-associated protein complex components also accumulate. The striking finding was that alpha-dystrobrevin-1 and neuronal nitric oxide synthase (nNOS) are almost completely lost from the membrane of these patients indicating that the myopathy may result from both the abnormal accumulation of proteins and an increase in ischaemic injury due to the loss of nNOS. We speculate that the loss of alpha-dystrobrevin from the membrane, and subsequent loss of nNOS, is due to the alpha-dystrobrevin-syncoilin-desmin interaction.