THE EFFECTS OF TNF-? ON THE PROTEIN METABOLISM AND THE UBIQUITIN SYSTEM GENE EXPRESSION IN ISOLATED SKELETAL MUSCLES / 解放军医学杂志

ABSTRACT

To study the effects of TNF ? on the protein metabolism and the ubiquitin system gene expression in isolated skeletal muscles, after dissecting and isolating the extensor digitorium longus (EDL) muscles, the in vitro oxygen rich muscle incubation system and as high performance liquid chromatography were used to assess proteolytic rate of the samples. The EDL muscles in study group were incubated with media containing 6 000 U/ml recombinant rat TNF ?. In control group, the media were of the same composition as that of the study group except recombinant rat TNF ?. The expressions of ubiquitin mRNA and C 2 mRNA in rat EDL muscles were determined by Northern blot analysis. No notable difference was observed in the total and myofibrillar proteolytic rate in EDL muscles between the two groups. The expressions of ubiquitin mRNA(2 4kb) and C2 mRNA of EDL muscle incubated with medium containing TNF ? were increased by 151% and 56%, respectively, as compared with those in control group. TNF ? could directly strengthen the function of ubiquitin dependent proteolytic system, but further studies are necessay to elucidate whether TNF ? could directly increase the proteolytic rate in skeletal muscle.