Figure 4.

SIRT1 knockdown reduces the protective effects of NMN on Dex-induced osteogenic inhibition. Si-NC or si-SIRT1 were transfected into BMSCs before Dex and NMN treatment. SIRT1-knockdown was confirmed by (A) RT-qPCR and (B) western blotting. (C) RT-qPCR was used to detect the SIRT1, PGC-1α and Runx2 mRNA expression levels in BMSCs. (D) Western blotting assays were used to determine the SIRT1, PGC-1α, ALP and Runx2 protein expression levels in BMSCs. (E) Alizarin red and ALP staining assays were used to assess the osteogenic ability of BMSCs. Scale bar, 20 µm. All experiments were performed ≥3 times. ***P<0.001, **P<0.01 *P<0.05 and ^nsP≥0.05, as indicated. Si, small interfering; NC, negative control; NMN, nicotinamide mononucleotide; Dex, dexamethasone; BMSC, bone mesenchymal stem cells; SIRT1, sirtuin 1; PGC, peroxisome proliferator-activated receptor gamma coactivator; ALP, alkaline phosphatase; Runx2, runt-related transcription factor 2; RT-qPCR, reverse transcription-quantitative PCR.