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Voltage-gated sodium channels in taste bud cells

DOI: 10.1186/1471-2202-10-20

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Abstract:

We describe the molecular and histological expression profiles of cation channels involved in electrical signal transmission from apical to basolateral membrane domains. TRPM5 was positioned immediately beneath tight junctions to receive calcium signals originating from sweet, bitter, and umami receptor activation, while PKD2L1 was positioned at the taste pore. Using mouse taste bud and lingual epithelial cells collected by laser capture microdissection, SCN2A, SCN3A, and SCN9A voltage-gated sodium channel transcripts were expressed in taste tissue. SCN2A, SCN3A, and SCN9A were expressed beneath tight junctions in subsets of taste cells. SCN3A and SCN9A were expressed in TRPM5 cells, while SCN2A was expressed in TRPM5 and PKD2L1 cells. HCN4, a gene previously implicated in sour taste, was expressed in PKD2L1 cells and localized to cell processes beneath the taste pore.SCN2A, SCN3A and SCN9A voltage-gated sodium channels are positioned to sense initial depolarizing signals stemming from taste receptor activation and initiate taste cell action potentials. SCN2A, SCN3A and SCN9A gene products likely account for the tetrodotoxin-sensitive sodium currents in taste receptor cells.Taste buds house specialized neuroepithelial cells that sense and transmit information regarding the composition of food [1]. These taste cells express receptors for sweet, bitter, umami (the savory taste of glutamate), sour and salty tastants in apical microvilli facing the saliva [2,3]. Following taste receptor activation, taste cells depolarize and fire action potentials resulting in the release of neurotransmitters to nerve fibers innervating basolateral membranes [4,5]. Segregation of taste receptors at the taste pore from the machinery involved in transmitting signals to nerve fibers is mediated by tight junctions, specialized protein networks that separate apical and basolateral membrane domains [6].Information regarding the composition of food flows from the apical to the basolateral doma

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