Fig. 3.

Transcriptional regulation of TXNIP promoter activity. (A) P69 cells were transiently transfected with a luciferase reporter under the control of the proximal TXNIP promoter (or empty pGL3 luciferase vector), along with a β-galactosidase vector. After 24 h, cells were cotransfected with an IGF1R expression vector (IGF1R-GFP), or empty vector (GFP), for an additional 24 h. At the end of the incubation, cells were harvested and luciferase and β-galactosidase values were measured. Promoter activities are expressed as luciferase normalized to β-galactosidase. (B) Autoregulation of the TXNIP gene. 3T3-L1 cells were transfected with a TXNIP promoter-luciferase gene (or empty pGL3), together with a β-galactosidase vector. Twenty-four hours after transfection, cells were cotransfected with a TXNIP expression vector (or empty GFP), and processed as described above. The results represent the mean ± SEM of three independent experiments. *P < 0.01 versus GFP-transfected cells.