Dystrophin isoforms and/or cross-reactive proteins on neurons and glial cells in control and mdx central nervous...

We studied the central nervous system (CNS) of control mice in comparison with that of mdx mice, immunohistochemically and immunoelectrophoretically, using 5 kinds of polyclonal antibodies against dystrophin (DMDP-II, 60-kDa, 30-kDa, P-20 and DMDP-IV) to determine whether or not and, if so, how dystrophin exists in the central nervous system. A positive dystrophin reaction was seen on the neurons and glial cells in both control and mdx tissue, without any immunohistochemical difference. In control mice, Western blot analysis showed two relatively clear bands corresponding to 400-kDa, with all 4 antibodies used (60-kDa, 30-kDa, P-20 and DMDP-IV), and 280-kDa, with 3 of them, the exception being 30-kDa, and 2 other faint bands corresponding to larger M(r) than 400-kDa, with 3 of them, the exception being P-20, respectively. In the mdx CNS, the 400-kDa band was absent, the other 3 bands being seen. The results suggest that dystrophin really exists in the control CNS, and some dystrophin isoforms or cross-reactive proteins exist on the neurons and glial cells in mdx as well as control mice. The localization of dystrophin in CNS also suggests its physiological function in the conduction system rather than a mechanical one, and a defect of it in CNS is a possible cause of the mental retardation in Duchenne muscular dystrophy.