Sepsis is associated with increased ubiquitin-conjugating enzyme E214k mRNA in skeletal muscle

Previous studies provided evidence that sepsis is associated with increased ubiquitin-proteasome-dependent protein breakdown in skeletal muscle. The 14-kDa ubiquitin-conjugating enzyme (E2(14k)) has been proposed to be a key regulator of the ubiquitin proteolytic pathway. We tested the hypothesis that E2(14k) message and protein levels are increased in skeletal muscle during sepsis. Sepsis was induced in rats by cecal ligation and puncture (CLP). Control rats were sham operated. E2(14k) mRNA and protein levels were quantitated 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(14k) transcript in the fast-twitch extensor digitorum longus muscle, whereas no chances were seen in the slow-twitch soleus muscle. E2(14k) protein levels were not influenced by sepsis in any of the muscles studied. Although the changes in the expression of the E2(14k) 1.2-kb transcript paralleled the differential effect of sepsis on protein breakdown in fast- and slow-twitch muscle, the potential role of E2(14k) in the regulation of sepsis-induced muscle proteolysis needs to be interpreted with caution, because the results demonstrated that increased message levels were not associated with increased E2(14k) protein levels.