Insulin Regulates Glucose Consumption and Lactate Production through Reactive Oxygen Species and Pyruvate Kinase M2
Figure 2
Insulin-induced PKM2 expression was inhibited by catalase. (a) HepG2 cells and Bel7402 cells were cultured to 70% confluence and then starved in serum-free medium for 24 h. The cells were exposed to 200 nM of insulin for 0 h, 3 h, 6 h, and 12 h. PKM2 levels were determined by immunoblotting. (b) Relative densities of PKM2/GAPDH from three independent experiments were normalized to those of control and presented as mean ± SD. * Significant difference compared to control without insulin treatment (). (c) The starved HepG2 cells and Bel7402 cells were pretreated with catalase (1500 U/mL) for 1 h, followed by stimulation with insulin (200 nM) for 6 h. Protein expression was determined by immunoblotting. (d) Results were expressed as a percentage of the control cultures and were the mean ± SD from three replications. (e) HepG2 cells and Bel7402 cells were treated as in (c). Total RNAs were extracted and used for real-time RT-PCR for detecting PKM2 and GAPDH mRNA levels. ** Significant difference compared to the control without insulin and catalase treatment treated without insulin and catalase treatment (); ## significant difference compared to the cells treated with insulin alone ().
