Ubiquitin gene expression is increased in human muscle undergoing neurogenic involvement

Histological features of neurogenic muscle involvement included type groupi ng, muscle fiber atrophy, and target fibers. In muscles with myofiber atrop hy and target fibers, we found an increased expression of the genes encodin g for the ubiquitin-ATP-dependent proteolytic system. Thus, in patients wit h target fibers, a 5.2- and a 3.9-fold increase were observed for the 2.4 a nd 1.2 kb transcripts, respectively, while in those with atrophic angulated hyperoxidative fibers, a 3.9- and a 4.4-fold increase were observed for th e 2.4 and 1.2 kb transcripts, respectively. It is suggested that the activa tion of this proteolytic system may be responsible for the skeletal muscle alterations that often accompany human muscle neurogenic involvement. (C) 1 999 Elsevier Science Ltd. All rights reserved.