Increased susceptibility to diet-induced obesity in GPRC6A receptor knockout mice

The recently identified G protein-coupled receptor GPRC6A is activated by dietary amino acids and expressed in multiple tissues. Although the receptor is hypothesised to exert biological impact on metabolic and endocrine-related parameters, the role of the receptor in obesity and metabolic complications is still elusive. In the present study, we investigated the impact of GPRC6A deficiency in a murine model of diet-induced obesity (DIO). Male Gprc6a knockout (KO) mice and WT littermates were subjected to a high-fat diet (HFD) for 25 weeks and exposed to comprehensive metabolic phenotyping. A significant increase in body weight, corresponding to a selective increase in body fat, was observed in Gprc6a KO mice exposed to an HFD relative to WT controls. The obese phenotype was linked to subtle perturbations in energy homoeostasis as GPRC6A deficiency resulted in chronic hyperphagia and decreased locomotor activity. Moreover, diet-induced obese Gprc6a KO mice had increased circulating insulin and leptin levels relative to WT animals, thereby demonstrating that endocrine abnormalities associate with the reported disturbances in energy balance. The phenotype was further accompanied by disruptions in glucose metabolism showing that Gprc6a KO mice on an HFD display increased susceptibility to develop metabolic-related disorders. Altogether, these data suggest that the amino acid sensing receptor GPRC6A plays an important role in resistance to DIO and metabolic complications. Future studies will illuminate the underlying molecular mechanisms mediating the herein reported findings and potentially facilitate the development of novel therapeutic compounds targeting the GPRC6A receptor.