Figure 3.
Glucocorticoids inhibit sirtuin 1 expression in tenocytes. Both (A) RNA (as measured by real-time qRT-PCR 7 h post-treatment, n=3) and (B) protein (as determined by western blotting) levels of sirtuin 1 were reduced in dexamethasone-treated cells compared with carrier (ethanol)-treated controls. Western blots were conducted on protein lysates from cells obtained from three different tissue donors. Blot shown is representative of all experiments. (C) The percentage of SA-βgal-positive cells was significantly lower in dexamethasone-treated tenocytes infected with an adenoviral vector containing a sirtuin 1 overexpression construct (adSirt1) compared with dexamethasone-treated tenocytes infected with a control adenoviral vector expressing GFP (adGFP). (D) Western blot demonstrating the effectiveness of the adSirt1 virus to prevent dexamethasone-induced inhibition of sirtuin 1 expression. Statistically significant differences between ethanol (EtOH) and dexamethasone (Dex) and between dexamethasone with and without sirt1 overexpression (adSirt1) are indicated by * (p<0.05).