RETRACTED: Activated macrophages utilize glycolytic ATP to maintain mitochondrial membrane potential and prevent apoptotic cell death(Retracted article. See vol. 24, pg. 1132, 2017)

We have previously analysed the bioenergetic consequences of activating J774.A1 macrophages (MU) with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) and found that there is a nitric oxide (NO)-dependent mitochondrial impairment and stabilization of hypoxia-inducible factor (HIF)-1 alpha, which synergize to activate glycolysis and generate large quantities of ATP. We now show, using tetramethylrhodamine methyl ester (TMRM) fluorescence and time-lapse confocal microscopy, that these cells maintain a high mitochondrial membrane potential (Delta Psi m) despite the complete inhibition of respiration. The maintenance of high Delta Psi m is due to the use of a significant proportion of glycolytically generated ATP as a defence mechanism against cell death. This is achieved by the reverse functioning of FoF1-ATP synthase and adenine nucleotide translocase (ANT). Treatment of activated MU with inhibitors of either of these enzymes, but not with inhibitors of the respiratory chain complexes I to IV, led to a collapse in Delta Psi m and to an immediate increase in intracellular [ATP], due to the prevention of ATP hydrolysis by the FoF1-ATP synthase. This collapse in Delta Psi m was followed by translocation of Bax from cytosol to the mitochondria, release of cytochrome c into the cytosol, activation of caspases 3 and 9 and subsequent apoptotic cell death. Our results indicate that during inflammatory activation 'glycolytically competent cells' such as MU use significant amounts of the glycolytically generated ATP to maintain Delta Psi m and thereby prevent apoptosis. Cell Death and Differentiation (2010) 17, 1540-1550; doi:10.1038/cdd.2010.27; published online 26 March 2010