Coupling Krebs cycle metabolites to signalling in immunity and cancer

Metabolic reprogramming has become a key focus for both immunologists and cancer biologists, with exciting advances providing new insights into the mechanisms underlying disease. There is now extensive evidence that intermediates and derivatives of the mitochondrial Krebs cycle-metabolites traditionally associated with bioenergetics or biosynthesis-also possess 'non-metabolic' signalling functions. In this review, we summarize the non-metabolic signalling mechanisms of succinate, fumarate, itaconate, 2-hydroxyglutarate isomers (D-2-hydroxyglutarate and L-2-hydroxyglutarate) and acetyl-CoA, with a specific focus on how such signalling pathways alter immune cell and transformed cell function. We believe that the insights gained from immune and cancer cells that are summarized here will also be useful for understanding and treating a range of other diseases.