The NO way to increase muscular utrophin expression?

Duchenne muscular dystrophy (DMD), a severe X-linked recessive disorder tha t results in progressive muscle degeneration, is due to a lack of dystrophi n, a membrane cytoskeletal protein. An approach to the search for a treatme nt is to compensate for dystrophin loss by utrophin, another cytoskeletal p rotein. During development, in normal as in dystrophic embryos, utrophin is found at the membrane surface of immature skeletal fibres and is progressi vely replaced by dystrophin. Thus, it is possible to consider utrophin as a 'foetal homologue' of dystrophin. In a previous work, we studied the effec t of L-arginine, the substrate of nitric oxide synthetase (NOS), on utrophi n expression at the muscle membrane. Using a novel antibody, we confirm her e that the immunocytochemical staining was indeed due to an increase in utr ophin at the sarcolemma. The result is observed not only on mdx tan animal model of DMD) myotubes in culture but also in mdx mice treated with L-argin ine. In addition, we show here the utrophin increase in muscle extracts of mdx mice treated with L-arginine, after electrophoretic separation and west ern-blotting using this novel antibody, and thus extending the electrophore tic results previously obtained on myotube cultures to muscles of treated m ice. (C) 2000 Academie des sciences/Editions scientifiques et medicales Els evier SAS.