Figure 3.

PGC-1β is regulated by components of the NF-κB alternative pathway. (A) C2C12 myoblasts were transfected with an empty vector, wild-type IKKα, or RelB expression constructs and differentiated for 3 d. RNA was isolated, and real-time RT-PCR analysis was performed probing for the indicated mitochondrial regulators. (B) C2C12 myoblasts were transfected with control siRNA (siControl) or siRNA oligonucleotides targeting IKKα or RelB. Cells were differentiated and analyzed as in A. (C) C2C12 myoblasts were transfected as in A, and after differentiation, media were collected and tested for lactate production and glucose content. Glucose consumption was calculated as total glucose present minus glucose that remained in the media. (D) Cells were transfected as in A, differentiated, and stained for lipid content with Oil red O. (E) C2C12 myoblasts were transfected with wild type or a KD form of IKKα, and after 5 d of differentiation without medium replenishment, cultured cells was photographed to highlight the change in the media color (top) or integrity of myotubes (bottom). Lactate values are representative of three independent experiments. *, P < 0.05. Error bars are means ± SEM. Bars, 100 µm.