Interaction of α-catulin with dystrobrevin contributes to integrity of dystrophin complex in muscle

摘要

The dystrophin complex is a multimolecular membrane-associated protein complex whose defects underlie many forms of muscular dystrophy. The dystrophin complex is postulated to function as a structural element that stabilizes the cell membrane by linking the contractile apparatus to the extracellular matrix. Abetter understanding of how this complex is organized and localized will improve our knowledge of the pathogenic mechanisms of diseases that involve the dystrophin complex. In a Caenorhabditis elegans genetic study, we demonstrate that CTN-1/alpha-catulin, a cytoskeletal protein, physically interacts with DYB-1/alpha-dystrobrevin (a component of the dystrophin complex) and that this interaction is critical for the localization of the dystrophin complex near dense bodies, structures analogous to mammalian costameres. We further show that in mouse alpha-catulin is localized at the sarcolemma and neuromuscular junctions and interacts with alpha-dystrobrevin and that the level of alpha-catulin is reduced in alpha-dystrobrevin- deficient mouse muscle. Intriguingly, in the skeletal muscle of mdx mice lacking dystrophin, we discover that the expression of alpha-catulin is increased, suggesting a compensatory role of alpha-catulin in dystrophic muscle. Together, our study demonstrates that the interaction between alpha-catulin and alpha-dystrobrevin is evolutionarily conserved in C. elegans and mammalian muscles and strongly suggests that this interaction contributes to the integrity of the dystrophin complex.