Fig. 6

DAPA inhibits SIRT1 ubiquitination and degradation by inhibiting TGF-β1-induced SIRT1 phosphorylation. A The positions of phosphorylated residues on human and mouse SIRT1 were marked. B Shown is a sequence analysis of human and mouse SIRT1. The serine position is indicated by the number. C Representative Western blotting showing SIRT1 expression in vivo and in vitro treated as indicated and quantified. D SIRT1 immunoprecipitation reaction was performed in endothelial cells and subjected to Western blot analysis for detecting SIRT1 ubiquitination. E The effects of MG132 on SIRT1 protein expression upon TGF-β1. *p < 0.05, **p < 0.01 vs. control group; #p < 0.05 vs. the TGF-β1 group