Succinate goes in to BAT, turning up the heat on metabolic disease

Metabolic disease and obesity develop when energy intake chronically exceeds energy expenditure. One way to combat these diseases is to increase energy expenditure by activating brown and beige fat, which produce heat through non-shivering thermogenesis. Beige and brown adipose tissue (BAT) contains a high density of mitochondria that are unique because they possess uncoupling protein-1 (UCP1), which uncouples mitochondrial oxidative respiration from ATP production to produce heat. Cold exposure drives intracellular lipolysis in the BAT and activates UCP1. However, pharmacological targeting of this pathway has proven to be difficult. Here, Edward Chouchani and colleagues identify a novel pathway of UCP1 activation upon cold exposure that is independent of the adrenergic cascade. The key molecule for this pathway is succinate, which is released into circulation largely by muscle, and is taken up exclusively by BAT, where it is quickly metabolized in the mitochondria. Mitochondrial oxidation of succinate boosts production of reactive oxygen species, driving UCP1 activation and heat production. Supplementation of drinking water with succinate causes robust suppression and reversal of weight gain and improves glucose tolerance in mice with diet-induced obesity. These effects are mediated by an elevation in whole-body energy expenditure. Dietary succinate thus may hold promise as therapy for metabolic diseases.