Fig. 2
Nicotine suppresses SIRT6 in vitro and in vivo. a Typical SDS-PAGE analysis of primary murine neurons treated for 24 h with increasing concentrations of cigarette smoke extract (0.5, 1, 2, 5, and 10%). b Representative SDS-PAGE analysis of primary neurons treated for 90 min with nicotine at a range of concentrations - (0.1, 1, 10, 100, and 1000 μM); note the dose dependent decrease of SIRT6 abundance. Neurons pretreated with 10 μm MG132 were exposed for 2 h. c Quantification of SIRT6 protein levels from B, n = 3 independent experiments. Note a dose-dependent decline of SIRT6 protein levels in response to nicotine, and elimination of this effect by proteasome inhibition (mean ± SEM, one-way ANOVA: *pnicotine = 0.008). d Representative SDS-PAGE analysis of brain lysates from animals treated with nicotine and vehicle-treated controls (same animals as shown in E). e Box plot of the concentration of serum cotinine in mice subjected to nicotine-supplemented water, n > 9 per treatment, two tailed t-test p < 10− 9. f Neurons treated with nicotine (1,10,100 μM) for 24 h, RNA was isolated and qRT-PCR was performed for SIRT6, two-tailed t-test performed between treatment and control groups. Note no significant difference in SIRT6 transcript levels (mean ± SEM, P-ANONA = 0.67)