Ubiquitin gene expression is increased in human muscle undergoing neurogenic involvement.

Histological features of neurogenic muscle involvement included type grouping, muscle fiber atrophy, and target fibers. In muscles with myofiber atrophy and target fibers, we found an increased expression of the genes encoding for the ubiquitin-ATP-dependent proteolytic system. Thus, in patients with target fibers, a 5.2- and a 3.9-fold increase were observed for the 2.4 and 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 the 2.4 and 1.2 kb transcripts, respectively. It is suggested that the activation of this proteolytic system may be responsible for the skeletal muscle alterations that often accompany human muscle neurogenic involvement.