Fig. 2
From: NADH elevation during chronic hypoxia leads to VHL-mediated HIF-1α degradation via SIRT1 inhibition
SIRT1-specific regulatd HIF-1α stability under hypoxic conditions. (A and B) Both the extent of NADH oxidation and the HIF-1α maintenance or recovery levels induced by SIRT1 were determined by measurement of NADH concentrations and HIF-1α protein in the presence of SIRT1-siRNA (A) or SIRT1- shRNA (B). (C) Association of SIRT1 activity with pyruvate-mediated recovery of HIF-1α was also validated in HeLa cells incubated with or without the SIRT1 inhibitors NAM (20 mM), EX-527 (1 µM), or sirtinol (25 µM); these inhibitors were present from commencement of hypoxia to 24 h, and 1 mM pyruvate was added 6 h before harvesting. Chronic decay of HIF-1α was monitored in HeLa cells cotransfected with Flag-tagged HIF-1α and either Myc-tagged wild type-SIRT1 or empty vector (-) (D); or in HeLa cells expressing wild-type SIRT1 (WT), dominant-negative SIRT1 (DN), or empty vector (V) (E). Statistical significance (p-value) was determined using the ANOVA-t-test. * : p < 0.05