Figure 6. Resveratrol inhibits insulin-induced MAPK and Akt phosphorylations in a SirT1-independent pathway.

HEK-293 cells were seeded at 5×10⁵/60 mm dish on day 0. Cells were transfected with 400 pmol of RNA oligonucleotide sequence against luciferase sequence in control group and same amount of RNA oligonucleotides against human SirT1 sequence in anti-SirT1 group using Oligofectamine reagent. Cells were transfected with RNA oligonucleotides for 30 h before they were serum-starved overnight. Both control and anti-SirT1 groups were treated with either DMSO or 100 μM resveratrol for 10 min before they were treated with 100 nM insulin for another 10 min. Total cell lysates were prepared for Western-blot analysis. (A) Western-blot analysis of the phosphorylation statuses of MAPK and Akt in response to insulin treatment in control cells or cells transfected with RNA oligonucleotides against SirT1. (B) The protein levels of SirT1 in cells described in (A) were analysed using Western-blot analysis. The results were also quantified using ImageJ (NIH Image) program. The average amount of SirT1 in control cells (lanes 1–4) were compared with those in cells transfected with RNA oligonucleotides against SirT1 (lanes 5–8) using Student's t test. ***P<0.001.