Figure 6.

Transactivation assay of engineered promoter containing 3XARE sites suggested that Metformin activated the Nrf2-dependent transcription through ARE in SRA-hLECs (A) and even reactivated in aging hLECs (B). (A) SRA-hLECs were transiently transfected with pRBGP2-3xARE-LUC plasmid or its mutant at all three ARE sites. 12–14 h later cells were treated with different concentrations of Metformin for 24 h as indicated, and relative LUC activity was monitored. All histograms are presented as mean ± S.D. values derived from three independent experiments. Vehicle control vs. Metformin-treated; * p < 0.05; ** p < 0.001. (B) Repression of Nrf2/ARE-mediated transcription in aging was reactivated by 1mM of Metformin treatment. Primary hLECs of variable ages were transiently transfected with pRBGP2-3xARE-LUC plasmid as indicated. 12–14 h after transfection hLECs were washed and treated with control or Metformin for 24 h. Relative LUC activity was monitored. The data represent the mean ± S.D. from two independent experiments. Younger vs. aging samples and control vs. Metformin-treated samples. ** p < 0.001.