NO ALTERATION IN GENE-EXPRESSION OF COMPONENTS OF THE UBIQUITIN-PROTEASOME PROTEOLYTIC PATHWAY IN DYSTROPHIN-DEFICIENT MUSCLES

Increased expression of critical components of the ubiquitin-dependent proteolytic pathway occurs in any muscle wasting condition so far stu died in rodents where proteolysis rises. We have recently reported sim ilar adaptations in head trauma patients [Mansoor et al. (1996) Proc. NatI, Acad. Sci. USA 93, 2714-2718]. We demonstrate here that the incr eased muscle protein breakdown seen in mdx mice only correlated with e nhanced expression of m-calpain, a Ca2+-activated proteinase, By contr ast, no change in mRNA levels for components of the ubiquitin-proteaso me proteolytic process was seen in muscles from both mdx mice and Duch enne muscular dystrophy patients, Thus, gene expression of components of this pathway is not regulated in the chronic wasting that character izes muscular dystrophy.