Figure 4.

4-1BB signaling activates the LKB1–AMPK–ACC signaling pathway. (a) Signaling diagram for fatty acid oxidation through LKB1–AMPK–ACC. (b) CD8⁺ T cells activated with 0.1 μg/ml anti-CD3 mAb for 16 h were stimulated with 5 μg/ml anti-4-1BB mAb or rat IgG. The CD8⁺ T cells were harvested at the indicated time points and Western blots were performed with antibodies specific for phosphorylated (p-) LKB1, AMPK and ACC as well as for β-actin. (c and d) Anti-CD3-activated CD8⁺ T cells were stimulated with rat IgG or anti-4-1BB mAb for 24 or 48 h. Western blots were performed with antibodies specific for the indicated proteins (c). Relative expression levels were calculated by dividing the densitometer reading of each protein by the value of β-actin (d). Naïve indicates freshly isolated CD8⁺ T cells. Data representative are of three independent experiments. Results in c are means±s.d. (*P<0.05; **P<0.01). Abbreviation: ACC, acetyl-CoA carboxylase.