A, effects of overexpression of SIRT1 on AMPK and ACC
phosphorylation. Cells grown in 6-well plates were transfected with 2 μg of
wild type SIRT1 or the inactive SIRT1 H355Y mutant. The ratios of
phosphorylated/total AMPK and ACC were increased by SIRT1 overexpression,
whereas SIRT1 H355Y had no effects (*, p < 0.05
versus pcDNA, n = 3). A similar increase in AMPK
phosphorylation was observed in other experiments. B, effects of
SIRT1 knockdown on AMPK and ACC phosphorylation in HEK293T cells. Transfection
of HEK293T cells with siRNA targeting SIRT1 decreased a ratio of
phosphorylated/total of AMPK and ACC (*, p < 0.05
versus siRNA control, n = 6). C, effects of SIRT1
knockdown on MARK1 phosphorylation in HepG2 cells. Lentiviral infection of
shRNA targeting sirt1 in HepG2 cells decreased the ratio of
phosphorylated to total MARK1 by 69% (*, p <0.05,
n = 6).