Regulation of PDH via cysteine oxidation on DLAT

Pyruvate dehydrogenase (PDH) complex is a key regulator of metabolism, controlling flux from glycolysis into the tricarboxylic acid (TCA) cycle. PDH is often dysregulated in metabolic diseases and cancer. We discover here that in addition to its well characterized regulation by phosphorylation, PDH activity is also regulated via inhibitory oxidation of three cysteines of the DLAT subunit - Cys488, Cys586 and Cys618. Oxidation of these cysteines increases under oxidative stress, and is highly prevalent in mouse and human tissues. This mechanism enables cells to efficiently fight oxidative stress. Under oxidative stress, cells execute a metabolic shift, blocking glycolytic flux into the TCA cycle to shunt glycolytic carbons toward the pentose phosphate pathway. This generates NADPH which cells use to detoxify H₂O₂ and to reduce oxidized cysteines. We find that DLAT oxidation is required for cells to mount an effective antioxidant response. Mutations preventing DLAT oxidation render PDH resistant to oxidative inhibition, impair NADPH generation, reduce peroxide detoxification, and sensitize cells to oxidative damage and death. DLAT oxidation also drives a Warburg-like metabolic phenotype of increased glucose uptake, elevated lactate secretion, and reduced TCA cycle activity. Thus DLAT oxidation is a redox-sensing mechanism that regulates PDH activity and central carbon metabolism.