Mitochondrial metabolic remodelling in response to genetic and environmental perturbations

Mitochondria are metabolic hubs within mammalian cells, and demonstrate significant metabolic plasticity. In oxygenated environments with ample carbohydrate, amino acid and lipid sources, they are able to utilise the tricarboxylic acid (TCA) cycle for the production of anabolic metabolites and ATP. However, in conditions where oxygen becomes limiting for oxidative phosphorylation, they can rapidly signal to increase cytosolic glycolytic ATP production, while awaiting hypoxia-induced changes in the proteome mediated by the activity of transcription factors such as Hypoxia-Inducible Factor 1 (HIF1). Hypoxia is a well-described phenotype of most cancers, driving many aspects of malignancy. Improving our understanding of how mitochondria change their metabolism in response to this stimulus may therefore elicit the design of new selective therapies. Many of the recent advances in our understanding of mitochondrial metabolic plasticity have been acquired through investigations of cancer-associated mutations in metabolic enzymes, including succinate dehydrogenase (SDH), fumarate hydratase (FH) and isocitrate dehydrogenase (IDH). This review will describe how metabolic perturbations induced by hypoxia and mutations in these enzymes have informed our knowledge in the control of mitochondrial metabolism, and will examine what this may mean for the biology of the cancers in which these mutations are observed.