Fig. 1.

NADH controls HIF-1α decay via involvement of SIRT1 during chronic hypoxia. (A) The timecourse of HIF-1α protein levels and intracellular NAD⁺ and NADH concentrations was determined in HeLa cells over 24 h of hypoxia. (B ~ E) Both the extent of NADH oxidation and the HIF-1α maintenance or recovery levels induced by pyruvate were determined by measurement of NAD⁺ and NADH concentrations, and HIF-1α protein, all under hypoxic conditions. Pyruvate (B) or NADH (C,D) or lactate (E) was added to confirm the existence of NADH-sensitive HIF-1α rescue. Statistical significance (p-value) was determined using the ANOVA-t-test. * : p < 0.05, ** : p < 0.01. NADH and pyruvate were added at a concentration of 1 mM