Cell mechanisms of gustatory lipids perception and modulation of the dietary fat preference

Dietary lipids are usually responsible of several metabolic disorders. Recent compelling evidences suggest that there is a sixth taste modality, destined for the detection of oro-gustatory fats. The lipid-binding glycoprotein CD36, expressed by circumvallate papillae (CVP) of the mouse tongue, has been shown to be implicated in oro-gustatory perception of dietary lipids. We demonstrate that linoleic acid (LA) by activating sPLA2, cPLA2 and iPLA2 via CD36, produced arachidonic acid (AA) and lysophosphatidylcholine (Lyso-PC) which triggered Ca2+ influx in CD36-positive taste bud cells (TBC), purified from mouse CVP. LA induced the production of Ca-2+ influx factor (CIF). CIF, AA and Lyso-PC exerted different actions on the opening of store-operated Ca2+ (SOC) channels, constituted of Orai proteins and regulated by STIM1, a sensor of Ca2+ depletion in the endoplasmic reticulum. We observed that CIF and Lyso-PC opened Orail channels whereas AA-opened Ca2+ channels were composed of Orail/Orai3. STIM1 was found to regulate LA-induced CIF production and opening of both kinds of Ca2+ channels. Furthermore, Stim1(-/-) mice lost the spontaneous preference for fat, observed in wild-type animals. Our results suggest that fatty acid-induced Ca2+ signaling, regulated by STIM1 via CD36, might be implicated in oro-gustatory perception of dietary lipids and the spontaneous preference for fat. Other cell types are involved in, and external factors can influence this preference. (C) 2014 Elsevier B.V. and Societe francaise de biochimie et biologie Moleculaire (SFBBM). All rights reserved.