Sepsis is associated with increased ubiquitin-conjugating enzyme E2(14k) mRNA in skeletal muscle

Previous studies provided evidence that sepsis is associated with increased ubiquitin-proteasome-dependent protein breakdown in skeletal muscle. The 1 4-kDa ubiquitin-conjugating enzyme (E2(14k)) has been proposed to be a key regulator of the ubiquitin proteolytic pathway. We tested the hypothesis th at E2(14k) message and protein levels are increased in skeletal muscle duri ng sepsis. Sepsis was induced in rats by cecal ligation and puncture (CLP). Control rats were sham operated. E2(14k) mRNA and protein levels were quan titated after Northern and Western blot analysis, respectively, 16 h after CLP or sham operation. Sepsis resulted in a 70% increase in the 1.2-kb E2(1 4k) transcript in the fast-twitch extensor digitorum longus muscle, whereas no chances were seen in the slow-twitch soleus muscle. E2(14k) protein lev els were not influenced by sepsis in any of the muscles studied. Although t he changes in the expression of the E2(14k) 1.2-kb transcript paralleled th e differential effect of sepsis on protein breakdown in fast- and slow-twit ch muscle, the potential role of E2(14k) in the regulation of sepsis-induce d muscle proteolysis needs to be interpreted with caution, because the resu lts demonstrated that increased message levels were not associated with inc reased E2(14k) protein levels.