Genetics of sweet taste preferences

Area of Science:

• Genetics
• Neuroscience
• Molecular Biology

Background:

• Inbred mouse strains exhibit significant variations in their preference for sweet solutions, attributed to underlying genetic differences.
• Previous research identified the saccharin preference (Sac) locus on chromosome 4 as a major determinant of these variations.
• Alterations in gustatory nerve responses to sweeteners correlate with allelic differences at the Sac locus, suggesting a role in sweet taste reception.

Purpose of the Study:

• To identify the specific gene responsible for regulating sweetener preference differences among mouse strains.
• To investigate the role of the identified gene in sweet taste perception and receptor function.

Main Methods:

• Positional cloning was employed to identify candidate genes within the Sac locus region.
• Genetic analysis, including introgression by serial back-crossing, was used to validate gene function.
• Haplotype analysis was performed to examine genetic variations associated with sweetener preference.

Main Results:

• The gene Tas1r3, encoding the T1R3 taste receptor protein, was identified and mapped to the Sac locus.
• Transferring the Tas1r3 allele from high-preference mice to low-preference mice rescued the preference phenotype.
• Two common Tas1r3 haplotypes were found, correlating with high and low sweetener preference levels in different mouse strains.

Conclusions:

• Tas1r3 is functionally equivalent to the Sac locus and plays a critical role in mediating sweetener preference in mice.
• The T1R3 receptor, when co-expressed with T1R2, is demonstrated to be responsive to sweeteners.
• While Tas1r3 is a key component, additional sweetness receptors may contribute to the overall perception of sweet taste.