Glutathione Regulation of Tumor Necrosis Factor-α-Induced NF-κB Activation in Skeletal Muscle-Derived L6 Cells

Abstract

TNFα is implicated in several skeletal muscle pathologies including muscle wasting of cachexia. Muscle wasting and other conditions such as physical exercise and immobilization are also associated with disturbances in muscle glutathione status. Hence, it was of interest to investigate the role of endogenous glutathione status in TNFα induced NF-κB activation in skeletal muscle-derived cells. TNFα proved to be a potent inducer of transient NF-κB activation in L6 myoblasts. In buthioninesulfoximine (BSO) treated cells, TNFα induced NF-κB activation was markedly potentiated suggesting that such activation is sensitive to cellular GSH, but may have been independent of high levels of intracellular GSSG. Because this activation was inhibited by the antioxidant pyrrolidinedithiocarbamate (PDTC) the involvement of reactive oxygen species in this activation system seems likely. NF-κB activation in L6 cells was also observed in response to direct H2O2treatment. Results from GSSG reductase inhibited cells suggest that GSSG may participate in, but is not required for, TNFα induced NF-κB activation. The inhibitory effect of PDTC on NF-κB activation correlated with its effect on ICAM-1 expression suggesting that this GSH status modifying agent not only influenced nuclear translocation of NF-κB proteins but also regulated κB dependent transcription.