The transaminase-?-amidase pathway is a redox switch in glutamine metabolism that generates a-ketoglutarate [RNA-seq_NIT2-GLS1-KO]

Oxidative stress is caused by short-lived molecules and metabolic changes are fast cellular responses. Here we studied how the endothelial cell metabolome reacts to oxidative challenges to identify redox-sensitive metabolic enzymes. H2O2 selectively increased a-ketoglutaramate (aKGM), a largely uncharacterized metabolite produced by glutamine transamination and an unrecognized intermediate of endothelial glutamine catabolism. The enzyme nitrilase-like 2 ?-amidase (NIT2) converts aKGM to a-ketoglutarate (aKG). Reversible oxidation of specific cysteine in NIT2 inhibited its catalytic activity. Furthermore, a variant in the NIT2 gene that decreases its expression is associated with increased plasma aKGM in humans. Endothelial-specific knockout mice of NIT2 exhibited increased levels of aKGM and impaired angiogenesis. Knockout of NIT2 impaired endothelial cell proliferation, sprouting and induced senescence. In conclusion, we show that the glutamine transaminase-?-amidase pathway is a metabolic switch where NIT2 is the redox-sensitive enzyme. The pathway is modulated in humans and functionally important for endothelial glutamine metabolism. Overall design: RNA-seq of human umbilical vein endothelial cells after knockout of NIT2 or GLS1, compared to non-targeting control.