Abstract: Objective To explore the impact of SIRT1 on p27Kip1 expression in vascular smooth muscle cells (VSMCs ) and investigate the possible mechanism. Methods A7r5 VSMCs were treated wtih H2O2 or oxLDL,then SIRT1 expression was detected by Western blot. Vascular injury models were also used to detect SIRT1 expression by Western blot. Primary rat VSMCs were infected with wild-type SIRT1 adenovirues and examined the expression of p27 by Western blot. Then we treated quiescent cells with nicotinamide, an inhibitor of the deacetylase activity of SIRT1, then detected changes of p27 expression. We also detected the interaction between SIRT1 and FOXO3a in VSMCs by co-immunoprecipitation. Results Endogenous SIRT1 was upregulated in a time-dependent manner in H2O2 or oxLDL treated A7r5 cells, and also upregulated in vascular injury models. SIRT1 overexpression significantly upregulated p27 expression under 10%FBS stimulation. NAM was found to inhibit p27 expression in a dose-dependent manner. The interaction between SIRT1 and FOXO3a was detectable in smooth muscle cells. Conclusion SIRT1 upregulates p27 expression in vascular smooth muscle cells.

Key words: SIRT1, p27Kip1, vascular smooth muscle cells