Variations in TAS1R taste receptor gene family modify food intake and gastric cancer risk in a Korean population

SCOPE

Human taste receptor type 1 (TAS1R, T1R) gene family mediates the perception of umami and sweet tastes and regulates metabolism. This study investigated whether variants in the TAS1R are associated with food intake and susceptibility to gastric cancer (GC).

METHODS AND RESULTS

A total of 1131 Koreans including 377 GC cases were analyzed to determine the dietary intake and genotype for 25 variants in TAS1R genes. Among the genotyped polymorphisms, six loci with a minor allele frequency >0.05 were tested for an association with dietary intake and GC risk. Findings suggest that TAS1R polymorphisms were associated with a variety of food intake that is beyond the known T1R-taste association. Furthermore, differential consumption for cigarettes and citrus fruits by TAS1R genetic variants may be linked to GC risk in males and females, respectively. Additionally, in males, TAS1R1 rs34160967 heterozygote showed an increased risk of GC (odds ratio: 1.52, 95% confidence interval: 1.10-2.09), independent of dietary intake. However, this GC-risk effect of TAS1R variants was not evident in females.

CONCLUSIONS

Genetic variants in TAS1R were associated with dietary consumption, which may be associated with GC risk. TAS1R1 rs34160967 may also modify the risk for GC independent of diet in Korean males.

Oligomerization of sweet and bitter taste receptors

The superfamily of G protein-coupled receptors (GPCRs) mediates numerous physiological processes, including neurotransmission, cell differentiation and metabolism, and sensory perception. In recent years, it became evident that these receptors might function not only as monomeric receptors but also as homo- or heteromeric receptor complexes. The family of TAS1R taste receptors are prominent examples of GPCR dimerization as they act as obligate functional heteromers: TAS1R1 and TAS1R3 combine to form an umami taste receptor, while the combination of TAS1R2 and TAS1R3 is a sweet taste receptor. So far, TAS2Rs, a second family of ~25 taste receptors in humans that mediates responses to bitter compounds, have been shown to function on their own, but if they do so as receptor monomers or as homomeric receptors still remains unknown. Using two different experimental approaches, we have recently shown that TAS2Rs can indeed form both homomeric and heteromeric receptor complexes. The employed techniques, coimmunoprecipitations and bioluminescence resonance energy transfer (BRET), are based on different principles and complement each other well and therefore provided compelling evidences for TAS2R oligomerization. Furthermore, we have adapted the protocols to include a number of controls and for higher throughput to accommodate the investigation of a large number of receptors and receptor combinations. Here, we present the protocols in detail.