Exposure to Hydrogen Peroxide Induces Oxidation and Activation of AMP-activated Protein Kinase

Although metabolic conditions associated with an increased AMP/ATP ratio are primary factors in the activation of 5'-adenosine monophosphate-activated protein kinase (AMPK), a number of recent studies have shown that increased intracellular levels of reactive oxygen species can stimulate AMPK activity, even without a decrease in cellular levels of ATP. We found that exposure of recombinant AMPK alpha beta gamma complex or HEK 293 cells to H2O2 was associated with increased kinase activity and also resulted in oxidative modification of AMPK, including S-glutathionylation of the AMPK alpha and AMPK beta subunits. In experiments using C-terminal truncation mutants of AMPK alpha (amino acids 1-312), wefound that mutation of cysteine 299 to alanine diminished the ability of H2O2 to induce kinase activation, and mutation of cysteine 304 to alanine totally abrogated the enhancing effect of H2O2 on kinase activity. Similar to the results obtained with H2O2-treated HEK 293 cells, activation and S-glutathionylation of the AMPK alpha subunit were present in the lungs of acatalasemic mice or mice treated with the catalase inhibitor aminotriazole, conditions in which intracellular steady state levels of H2O2 are increased. These results demonstrate that physiologically relevant concentrations of H2O2 can activate AMPK through oxidative modification of the AMPK alpha subunit. The present findings also imply that AMPK activation, in addition to being a response to alterations in intracellular metabolic pathways, is directly influenced by cellular redox status.