Figure 3.

SIRT1 is degraded by the proteasome in response to CSE. A) BEAS-2B cells were treated with the proteasome inhibitor N-Acetyl-Leu-Leu-Nle-CHO (ALLN; 5 μM) or MG-132 (10 μM) for 30-min pretreatment prior to a 6-h CSE (1 and 1.5%) treatment. Whole-cell extracts were analyzed by Western blot (representative of 3 separate experiments). β-Actin was used as a loading control. B) SIRT1 was immunoprecipitated from whole-cell extracts from A and used for the SIRT1 deacetylase activity assay. **P < 0.01, ***P < 0.001 vs. control.