Fig. 7.

SIRT inhibitors inhibit STAT3 phosphorylation in renal fibroblasts. NRK-49F cells were cultured in medium with 5% fetal bovine serum (FBS) and then treated with sirtinol (0–50 μM), EX527 (0–100 μM), and AGK2 (0–100 μM) for 36 hours (A–E and G). NRK-49F cells were transfected with siRNA targeting SIRT1 and SIRT2 or scrambled siRNA and incubated in normal culture medium with 5% FBS, and cells were harvested 48 hours after transfection for immunoblot analysis (F and H). After treatment, cell lysates were prepared and subjected to immunoblot analysis with antibodies for phospho-STAT3 (pSTAT3; Tyr705) or STAT3 (A, B, E, and F). Representative immunoblots from three experiments are shown. The phosphorylated and total levels of STAT3 were quantified by densitometry, and phosphorylated protein levels were normalized to total protein levels (C, D, G, and H). Values are the means ± S.D. of three independent experiments. Bars with different letters (a–d) are significantly different from one another (P < 0.01). Con, control.