T1R taste receptors and the regulation of carbohydrate intake and metabolism in mammals

Taste receptors type 1, T1R, encoded by Tas1 genes play a key role in sweet and amino acid taste perception in vertebrates. Significant differences in food preferences, described in different groups of animals, could be associated with interruption of expression of some genes encoding these proteins. Numerous polymorphisms of these genes were found in mammals, including humans and mice. These polymorphisms entail an increase in the preference and consumption of sweet substances and affect receptor sensitivity. This makes the study of this system highly relevant in light of the current situation with diabetes and obesity. Although T1Rs were originally cloned in taste cells, the subsequent studies have significantly expanded the understanding of their expression and suggested they had a functional role in parts of the body other than the oral cavity. Their expression is found along the digestive tract and in endocrine tissues (in enteroendocrine and absorptive intestinal cells, α and β-cells of pancreatic islet), liver, adipocytes, in brain structures involved in metabolism and nutrition regulation, osteocytes, and this list is constantly expanding. At the same time, metabolic gene effects still remain poorly understood. This review summarizes the latest data showing that T1R receptors not only influence food choices, but are also involved in controlling hormonal responses that regulate carbohydrate intake and metabolism in body tissues and fat accumulation.