Ketone body receptor GPR43 regulates lipid metabolism under ketogenic conditions

Ketone bodies, mainly β-hydroxybutyrate and acetoacetate, are important alternative energy sources in a state of energy deficit or metabolic crisis. The consumption of ketogenic diets, such as low-carbohydrate and medium-chain triglyceride diets, and time-restricted feeding lead to ketogenesis, which influences longevity and health. β-Hydroxybutyrate also acts as a signaling molecule via GPR109A and GPR41; however, to date, the specific G protein-coupled receptors responsible for acetoacetate and its physiological functions remain unknown. In this study, we demonstrate that acetoacetate acts as an endogenous agonist of GPR43 by ligand screening in a heterologous expression system, and that it, rather than short-chain fatty acids, maintains energy homeostasis via GPR43-mediated lipid metabolism under ketogenic conditions.