TNF can directly induce the expression of ubiquitin-dependent proteolytic system in rat soleus muscles.

Incubation of isolated rat soleus muscles in the presence of human recombinant TNF-alpha (10,000 U/ml) resulted in an important increase in ubiquitin gene expression (over 50%). Although previous studies involving cytokine administration in vivo (1) have demonstrated an action on ubiquitin-dependent proteolysis, this is the first report demonstrating a direct action of the cytokine on protein breakdown in incubated rat skeletal muscle.