title: Ca2+ signaling in taste bud cells and spontaneous preference for fat: unresolved roles of CD36 and GPR120.
abstract: Recent compelling evidences from rodent and human studies raise the possibility for an additional sixth taste modality devoted to oro-gustatory perception of dietary lipids. Understanding the mechanisms underlying oro-gustatory detection of dietary fat is critical for the prevention and treatment of obesity. A number of studies have suggested that lingual CD36, a glycoprotein, highly expressed by circumvallate papillae of the tongue, is implicated in the perception of dietary fat taste. G protein-coupled receptors (GPCRs) are important signaling molecules for many aspects of cellular functions. It has been shown that these receptors, particularly GPR120, are also involved in lipid taste perception. We have shown that dietary long-chain fatty acids (LCFAs), in CD36-positive taste bud cells (TBC), induce increases in free intracellular Ca(2+) concentrations, [Ca(2+)]i, by recruiting Ca(2+) from endoplasmic reticulum (ER) pool via inositol 1,4,5-triphosphate production, followed by Ca(2+) influx via opening of store-operated Ca(2+) (SOC) channels. GPR120 is also coupled to increases in [Ca(2+)]i by dietary fatty acids. We observed that stromal interaction molecule 1 (STIM1), a sensor of Ca(2+) depletion in the ER, mediated fatty acid-induced Ca(2+) signaling and spontaneous preference for fat in the mouse. In this review article, we discuss the recent advances and unresolved roles of CD36 and GPR120 in lipid taste signaling in taste bud cells.
authors.affiliation: Physiologie de la Nutrition & Toxicologie, UMR U866 INSERM/Université de Bourgogne/Agro-Sup, 6 Boulevard Gabriel, Dijon 21000, France; Laboratoire de Nutrition, Université Abdou Moumouni, Niamey, Niger.
authors.forename: Souleymane
authors.initials: S
authors.lastname: Abdoul-Azize
authors.forename: Subramaniam
authors.initials: S
authors.lastname: Selvakumar
authors.forename: Hassimi
authors.initials: H
authors.lastname: Sadou
authors.forename: Philippe
authors.initials: P
authors.lastname: Besnard
authors.forename: Naim Akhtar
authors.initials: NA
authors.lastname: Khan
mesh_terms: D000818:Animals; D018955:CD36 Antigens / Q000502:physiology*; D020013:Calcium Signaling; D004041:Dietary Fats / Q000378:metabolism*; D006801:Humans; D043562:Receptors, G-Protein-Coupled / Q000502:physiology*; D013649:Taste; D013650:Taste Buds / Q000166:cytology / Q000378:metabolism*
chemical_list: D018955:CD36 Antigens; D004041:Dietary Fats; C519853:FFAR4 protein, human; D043562:Receptors, G-Protein-Coupled
keywords: AA; CD36; CIF; Ca(2+) influx factor; Ca(2+)-independent phospholipase A(2); CaM; Fatty acids; G protein-coupled receptors; GL; GPCR; GPR120; LCFA; Lipids; Lyso-PC; PLC; PTK; SFK; SOC; SOCE; STIM1; Src family kinases; Stim1; TBC; TRC; TRPM5; Taste receptor cells; [Ca(2+)]i; arachidonic acid; cPLA(2); calcium influx factor; calmodulin; cytosolic phospholipase A(2); free intracellular calcium concentration; glossopharyngeal nerve; iPLA(2); long-chain fatty acid; lyso-phosphatidylcholine; phospholipase C; protein tyrosine kinase; store-operated Ca(2)(+) entry; store-operated Ca(2+) channel; stromal interaction molecule 1; taste bud cells; taste receptor cells; transient receptor potential melastatin-5