There is evidence that burn injury stimulates ubiquitin–proteasome-dependent protein breakdown in skeletal muscle. In this proteolytic pathway, protein substrates are conjugated to multiple molecules of ubiquitin, whereafter they are recognized, unfolded and degraded by the multicatalytic 26 S protease complex. The 20 S proteasome is the catalytic core of the 26 S protease complex. The influence of burn injury on the expression and activity of the 20 S proteasome has not been reported. We tested the hypothesis that burn injury increases 20 S proteasome activity and the expression of mRNA for the 20 S proteasome subunits RC3 and RC7. Proteolytic activity of isolated 20 S proteasomes, assessed as activity against fluorogenic peptide substrates, was increased in extensor digitorum longus muscles from burned rats. Northern-blot analysis revealed that the expression of mRNA for RC3 and RC7 was increased by 100% and 80% respectively following burn injury. Increased activity and expression of the 20 S proteasome in muscles from burned rats support the concept that burn-induced muscle cachexia is at least, in part, regulated by the ubiquitin–proteasome proteolytic pathway.
Burn injury upregulates the activity and gene expression of the 20 S proteasome in rat skeletal muscle
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Cheng-Hui FANG, Bing-Guo LI, David R. FISCHER, Jing Jing WANG, Herbert A. RUNNELS, John J. MONACO, Per-Olof HASSELGREN; Burn injury upregulates the activity and gene expression of the 20 S proteasome in rat skeletal muscle. Clin Sci (Lond) 1 September 2000; 99 (3): 181–187. doi: https://doi.org/10.1042/cs0990181
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