Investigating the Effects of TNF-α knockdown Gene on Insulin Resistance in C2C12 Muscle Cells in the Presence and Absence of Palmitate

Insulin resistance plays a major role in type 2 diabetes and obesity. In this disorder، lipid accumulation is accompanied by increased TNF-α expression in the muscle. The aims of this study were to evaluate the effects of tumor necrosis factor-α (TNF-α) gene knockdown on key elements of insulin signaling pathway (IRS-1 and Akt) and insulin resistance in C2C12 muscle cells in the presence and absence of palmitate.

To knockdown protein expression of TNF-α، the C2C12 cells were transfected with the shRNA containing antisense sequence of murine TNF-α gene. The analysis of TNF-α protein expression and phosphorylation and protein levels of IRS-1and Akt were subsequently detected by western blot.

In TNF-α knockdown cells، the protein expression level of TNF-α was reduced by 58%. Under treatment with palmitate، insulin stimulated phosphorylation of IRS-1 (Tyr632) and Akt (Ser473) in knockdown cells was increased 1. 7 and 2. 6 fold، respectively، compared to the controls.

Our findings showed that decreasing the TNF-α protein level can enhance the activity of the important elements of insulin signaling pathway (IRS-1 and Akt)، leading to the improvement of insulin resistance in myotubes، data suggesting that TNF-α may potentially be a therapeutic target for fatty acid induced insulin resistance observed in type 2 diabetes and metabolic syndrome.