Fig. 6
From: SIRT7 antagonizes TGF-β signaling and inhibits breast cancer metastasis
SIRT7 promotes β-TrCP1-mediated SMAD4 degradation. a Immunoblots showing SMAD4 protein levels in Scramble (Ctrl) or shSIRT7-treated MDA-MB-231 cells. b Immunoblots showing SMAD4 levels in the presence of CHX, with or without ectopic SIRT7 or NAM. c Wild-type, K428R, and K428Q mutants of SMAD4 levels in the presence of CHX (50 μg/ml). Quantification was performed by Image J; data were presented as mean ± S.D. d Ubiquitination levels of SMAD4 WT and mutants. e Immunoblots showing SMAD4 level in cells expressing ectopic SIRT7, treated with control or β-TrCP1 siRNA. f Immunoblots showing polyubiquitination of SMAD4 in the presence or absence of ectopic SIRT7 or β-TrCP1 siRNA. g Immunoprecipitation showing the binding capacity between Flag-β-TrCP1 and various HA-SMAD4 mutants. h, i Ubiquitination levels of HA-SMAD4 K428R h and K428Q i in cells treated with control or β-TrCP1 siRNAs or ectopic β-TrCP1 as indicated
