The highly ordered cortical microtubule lattice of skeletal muscle is disorganized in dystrophin-deficient mdx mice. Implicated mechanisms include loss of dystrophin binding, altered α-tubulin posttranslational modification, expression of a β-tubulin involved in regeneration, and reactive oxygen species (ROS). Here we show that the transverse microtubules in mdx muscle expressing miniaturized dystrophins are rapidly lost after eccentric contraction. Analysis of mdx lines expressing different dystrophin constructs demonstrate that spectrin-like repeats R4-15 and R20-23 were required for mechanically stable microtubules. Microtubule loss was prevented by the non-specific antioxidant N-acetylcysteine while inhibition of NADPH oxidase 2 had only a partial effect, suggesting that ROS from multiple sources mediate the rapid loss of transverse microtubules after eccentric contraction. Finally, ablation of α-dystrobrevin, β- or γ-cytoplasmic actin phenocopied the transverse microtubule instability of miniaturized dystrophins. Our data demonstrate that multiple dystrophin domains, α-dystrobrevin and cytoplasmic actins are necessary for mechanically stable microtubules.
Bibliographical noteFunding Information:
The TMT proteomic screen was performed at the University of Minnesota Center for Mass Spectrometry and Proteomics. This work was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases [ R01 AR042423 to J.M.E. and F13 AR073629 to D.M.N.]. The funding source had no role in conduct of research or article preparation.
- Cytoplasmic actin
- Duchenne muscular dystrophy
- NADPH oxidase
- Skeletal muscle