Research Paper Volume 5, Issue 3 pp 174—182

Figure 2. Activation of SIRT1 gene expression by syringaresinol through FOXO3 binding. (A) Relative activities of luciferase expressed from different SIRT1 promoter constructs in HUVECs at PDL14 treated with (SYR) and without (Control) 50 μM syringaresinol. (B) Predicted binding sites for FOXOs, p53, HIFs, and NF-κB in the proximal SIRT1 promoter region, and relative SIRT1 mRNA levels (qRT-PCR) after knock-down of NF-κB, HIF-1α, HIF-1α, p53, FOXO1, and FOXO3 by gene-specific siRNAs in HUVECs at PDL14 treated with (SYR) and without (Control) 50 μM syringaresinol. The knock-down (KD) efficiency (%) of each is indicated. (C) Binding of FOXO3 (chromatin immunoprecipitation followed by qPCR: qChiP) to SIRT1 promoter region (−533 to −352) in HUVECs at PDL14 treated with (+) and without (−) 50 μM syringaresinol. (D) Relative luciferase activities of SIRT1 promoter constructs harboring site-specific changes (indicated as X) in each (−517 or −457) of predicted FOXO3 binding sites in HUVECs at PDL14 treated with (SYR) and without (Control) 50 μM syringa-resinol. All the results are either representatives or means ± S.E of at least three independent experiments. Significance was assessed by t-test. **P < 0.01.