FIGURE 5.

FOXO1 effects on glucose-induced TXNIP expression. A, INS-1 cells were transiently transfected with FOXO1 expression plasmid, FOXO1 DNA-binding mutant (H215R), or LacZ control plasmid and incubated in 5 mm low glucose (LG) or 25 mm high glucose (HG) medium 24 h after transfection. Cells were harvested 72 h after transfection, and TXNIP protein levels were measured by Western blotting. B, TXNIP protein levels were corrected for β-actin in six independent experiments and quantified. C, INS-1 cells co-transfected with FOXO1 expression plasmid, FOXO1 DNA-binding mutant (H215R) or LacZ control plasmid and the full-length TXNIP promoter luciferase reporter construct were incubated in 5 mm low glucose or 25 mm high glucose medium 24 h after transfection. Cells were harvested 48 h after transfection, and luciferase activity was measured. Bars represent mean -fold change ± S.E. (error bars); n = 3–6.