FIGURE 8.

Overexpression of CrAT in primary human skeletal myotubes promotes glucose uptake and oxidation. Skeletal myocytes were pretreated with recombinant adenoviruses encoding β-galactoside (β-gal) or Myc-tagged rat CrAT. Protein expression of rCrAT in primary human myotubes was detected using an antibody that recognizes rodent but not human CrAT (a). CrAT localization was evaluated using mitochondrial (Mito) and cytosolic (Cyto) fractions and whole cell lysates (WC) prepared from C2C12 myoblasts exposed to rAdCMV-CrAT, followed by SDS-PAGE and Western blot analysis using the aforementioned antibody (b). Metabolic experiments were performed 72 h after virus treatment. Acetylcarnitine levels in cell lysates and medium (c) was assessed 24 h after addition of carnitine. Myotube oxidation of [U-¹⁴C]glucose (d) and cellular uptake of [2-³H]deoxyglucose (e) were assessed during a 2-h exposure to radiolabel in the presence or absence of 100 μm oleate. Data represent the mean ± S.E. from 3–4 separate experiments. Results were analyzed by two-way analysis of variance. *, p < 0.05, effect of oleate compared with basal. #, p < 0.05, effect of CrAT compared with β-galactosidase.