6533b86cfe1ef96bd12c7de9

RESEARCH PRODUCT

The study of calcium signaling in lipid gustatory cells in mice

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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 lyso-phosphatidylcholine (Lyso-PC) which triggered Ca2+ influx in CD36-positive taste bud cells (TBC), purified from mouse CVP. LA induced the production of Ca2+ 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 used siRNA technology and transgenic mice models and observed that CIF and Lyso-PC opened Orai1 channels whereas AA-opened Ca2+ channels were composed of Orai1/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. The CD36-positive TBC from Stim1–/– mice also failed to release serotonin into extracellular environment. 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