title: The gustin (CA6) gene polymorphism, rs2274333 (A/G), as a mechanistic link between PROP tasting and fungiform taste papilla density and maintenance.
abstract: Taste sensitivity to PROP varies greatly among individuals and is associated with polymorphisms in the bitter receptor gene TAS2R38, and with differences in fungiform papilla density on the anterior tongue surface. Recently we showed that the PROP non-taster phenotype is strongly associated with the G variant of polymorphism rs2274333 (A/G) of the gene that controls the salivary trophic factor, gustin. The aims of this study were 1) to investigate the role of gustin gene polymorphism rs2274333 (A/G), in PROP sensitivity and fungiform papilla density and morphology, and 2) to investigate the effect of this gustin gene polymorphism on cell proliferation and metabolic activity. Sixty-four subjects were genotyped for both genes by PCR techniques, their PROP sensitivity was assessed by scaling and threshold methods, and their fungiform papilla density, diameter and morphology were determined. In vitro experiments examined cell proliferation and metabolic activity, following treatment with saliva of individuals with and without the gustin gene mutation, and with isolated protein, in the two iso-forms. Gustin and TAS2R38 genotypes were associated with PROP threshold (p=0.0001 and p=0.0042), but bitterness intensity was mostly determined by TAS2R38 genotypes (p<0.000001). Fungiform papillae densities were associated with both genotypes (p<0.014) (with a stronger effect for gustin; p=0.0006), but papilla morphology was a function of gustin alone (p<0.0012). Treatment of isolated cells with saliva from individuals with the AA form of gustin or direct application of the active iso-form of gustin protein increased cell proliferation and metabolic activity (p<0.0135). These novel findings suggest that the rs2274333 polymorphism of the gustin gene affects PROP sensitivity by acting on fungiform papilla development and maintenance, and could provide the first mechanistic explanation for why PROP super-tasters are more responsive to a broad range of oral stimuli.
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Monserrato, Italy.
authors.forename: Melania
authors.initials: M
authors.lastname: Melis
authors.forename: Elena
authors.initials: E
authors.lastname: Atzori
authors.forename: Stefano
authors.initials: S
authors.lastname: Cabras
authors.forename: Andrea
authors.initials: A
authors.lastname: Zonza
authors.forename: Carla
authors.initials: C
authors.lastname: Calò
authors.forename: Patrizia
authors.initials: P
authors.lastname: Muroni
authors.forename: Mariella
authors.initials: M
authors.lastname: Nieddu
authors.forename: Alessandra
authors.initials: A
authors.lastname: Padiglia
authors.forename: Valeria
authors.initials: V
authors.lastname: Sogos
authors.forename: Beverly J
authors.initials: BJ
authors.lastname: Tepper
authors.forename: Iole
authors.initials: I
authors.lastname: Tomassini Barbarossa
mesh_terms: D000328:Adult; D000818:Animals; D002256:Carbonic Anhydrases / Q000235:genetics*; D002460:Cell Line; D049109:Cell Proliferation; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005838:Genotype; D006041:Goats; D006801:Humans; D008297:Male; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011441:Propylthiouracil / Q000494:pharmacology*; D020033:Protein Isoforms / Q000235:genetics; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D012463:Saliva / Q000737:chemistry; D013649:Taste / Q000187:drug effects / Q000235:genetics*; D013650:Taste Buds / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013652:Taste Threshold / Q000187:drug effects / Q000235:genetics; D000098706:Taste Receptors, Type 2
chemical_list: D020033:Protein Isoforms; D043562:Receptors, G-Protein-Coupled; D000098706:Taste Receptors, Type 2; D011441:Propylthiouracil; D002256:Carbonic Anhydrases; C477051:carbonic anhydrase VI
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