Functional expression of the extracellular-Ca2+-sensing receptor in mouse taste cells

Bystrova, M. F.; Romanov, Roman A.; Rogachevskaja, Olga A.; Churbanov, Gleb D.; Kolesnikov, Stanislav S.

doi:10.1242/jcs.061879

Cited by 65 publications

(45 citation statements)

References 83 publications

(107 reference statements)

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“…Previous studies have described the expression of this receptor in different tissues and cells e.g. soft palate, liver, blood vessels and taste cells (Kuang et al 2005;Wellendorph et al 2007;Harno et al 2008;Bystrova et al 2010). As all identified endogenous agonists for family C receptors are nutrient-like molecules reaching from ions and sugars to amino acids (Quiocho and Ledvina 1996;Wellendorph et al 2009a;Geraedts et al 2010), the broadly tuned L-amino-acid receptor GPRC6A presents a plausible candidate for being a nutrient sensor of emerging physiological significance (Kuang et al 2005;Wellendorph et al 2007;Wellendorph et al 2009a).…”

Section: Introductionmentioning

confidence: 99%

Nutrient sensing receptors in gastric endocrine cells

2011

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Sensing protein breakdown products in the luminal content is of particular importance for the regulation of digestive activities in the stomach which are mainly governed by gastric hormones. The molecular basis for tuning the release of hormones according to the protein content is still elusive. In this study we have analysed the murine stomach for candidate nutrient receptors. As a promising candidate we have concentrated on the broadly tuned amino acid receptor GPRC6A. Expression of GPRC6A could be demonstrated in different regions of the murine stomach; especially in the gastric antrum. Using immunohistochemical approaches, a large cell population of GPRC6A-positive cells was visualized in the basal half of the antral gastric mucosa. Molecular phenotyping of GPRC6A-immunoreactive cells revealed that most of them contained the peptide hormone gastrin. A small population turned out to be immunoreactive for somatostatin. In search for additional amino acid receptors in antral gastric mucosa, we obtained evidence for expression of the gustatory amino acid receptor subunit T1R3 and the calcium-sensing receptor CaSR. Many CaSR-cells were found in the gastric antrum and most of them also contained gastrin; very similar to GPRC6A-cells. In contrast, T1R3 was found only in a small population of gastrin-negative cells. The finding that GPRC6A-and CaSR-receptors are both expressed in many if not all gastrin cells strongly suggests that both receptor types are co-expressed in the same cells, where they could form heterodimers providing a unique response spectrum of these cells.

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Section: Introductionmentioning

confidence: 99%

Nutrient sensing receptors in gastric endocrine cells

2011

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“…As was mentioned above, TRPM5 are the key elements of the cascade of taste transduction functioning in type-II taste cells specialized in the recognition of bitter, sweet, and umami stimuli. Using electrophysiological criteria that we proposed earlier, the type-II cells can be identified rather unambiguously [9,13,14]. We showed that nonselective ion channels, which resemble, by their kinetics of activation and the property of outward rectification, the recombinant TRPM5, do exist in these cells.…”

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confidence: 60%

Identification of TRPM5 Ion Channels in Type-II Taste Cells of Mice

et al. 2011

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TRPM5 are ion channels belonging to the TRP family, which demonstrate a nonselective permeability for monovalent cations and are activated by an increase in the intracellular calcium level. TRPM5 are present in taste receptor cells of type II responsible for reception of bitter, sweet, and umami taste sensations. Knockout of the trpm5 gene in mice results in a nearly complete loss of sensitivity to taste stimuli of the above-mentioned modalities (taste blindness). The physiological activity of TRPM5 in taste receptive cells has practically not been studied. Using a patch-clamp technique, we carried out a comparative analysis of the properties of recombinant TRPM5 and Ca 2+ -activated membrane channels in type-II taste cells in mice. Dialysis of the studied cells with a high-Ca 2+ solution and application of a calcium ionophore, ionomycin, caused activation of outward-rectification ion channels permeable for Na + , Cs + , and K + in CHO-strain cells with exogenous TRPM5. These channels were blocked by 100 µM triphenylphosphine oxide (TPPO). Calcium-activated channels in type-II taste cells also possessed analogous properties. Application of the calcium ionophore ionomycin or a stepwise increase in the intracellular Ca 2+ level using photolysis (uncaging) caused activation of channels nonselective with respect to Na + and Cs + and impermeable for N-methyl-D-glucamine (NMDG + ). These channels had the current-voltage characteristics of outward rectification and a high thermosensitivity (Q 10 = 6.7 ± 0.5); they could be blocked by TPPO. It should be emphasized that TRPM5 were specific with respect to type-II cells. An increase in the intracellular calcium level induced the appearance of Cl -current in type-I cells and did not influence the basic current in type-III cells.

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“…6C). We found that this effect is related to the functioning of calciumsensitive receptors (CaSRs), i.e., receptors associated with G protein belonging to the C family, in cells of this type [17]. These receptors can be activated by nearly all L-amino acids, but they demonstrate maximum sensitivity to phenylalanine and minimum sensitivity to arginine (D).…”

Section: Resultsmentioning

confidence: 99%

“…For synthesis of the first chain of cDNA with RNA of the matrix, we used reverse transcriptase SuperScriptIII (Invitrogen, USA) and oligo(dT) primer. To amplify specific parts of cDNA of the corresponding receptors with the help of PCR, we used pairs of gene-specific primers [2,11,[14][15][16][17] constructed based on the corresponding nucleotide sequence from the GenBank databases.…”

Section: Methodsmentioning

confidence: 99%

Cell-to-Cell Communication in the Taste Bud: ATP and Acetylcholine as Primary Mediators

et al. 2012

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It was shown that physiological processes in taste buds (peripheral sensory gustatory organs in vertebrates) are realized with the involvement of several signal systems. In these structures, a number of "classical" neurotransmitters, including glutamate, serotonin, GABA, ATP, noradrenaline, and others, as well as receptors to these agents, were identified. The physiological roles of the above systems (separate ones and all as a whole) remain, however, far from final elucidation. We studied purinergic and cholinergic systems in the taste buds. Based on the data obtained in behavioral experiments using knockout animals, which indicated that ATP is an afferent neurotransmitter, we found stimulation-induced secretion of ATP by type-II cells. The release of ATP does not require the entry of external calcium and is mediated by ion channels permeable for ATP. The obtained data allowed us to explain the fact that classical synaptic structures are absent in the type-II cells. The type-I cells coat other elements including type-II cells; they provide formation of compartments in the intercellular space of the taste buds (this limits ATP diffusion). We showed that taste cells of just type I mostly generate calcium signals in response to the action of ATP and acetylcholine. These cell responses are generated with the involvement of metabotropic purine receptors (isoforms P2Y1, P2Y2, and P2Y4) and muscarinic receptors (isoforms M1, M3, and M5), respectively. Functioning of these receptors is combined with a phosphoinositide cascade, mobilization of intracellular Са 2+ , and subsequent activation of calciumactivated Cl -channels. It seems probable that purinergic and cholinergic signal systems in type-I cells are elements of negative feedback in the taste buds, which promote the process of adaptation to the action of gustatory stimuli.

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Functional expression of the extracellular-Ca2+-sensing receptor in mouse taste cells

Abstract: SummaryThree types of morphologically and functionally distinct taste cells operate in the mammalian taste bud. We demonstrate here the expression of two G-protein-coupled receptors from the family C, CASR and GPRC6A, in the taste tissue and identify transcripts for

Cited by 65 publications

References 83 publications

Nutrient sensing receptors in gastric endocrine cells

Nutrient sensing receptors in gastric endocrine cells

Identification of TRPM5 Ion Channels in Type-II Taste Cells of Mice

Cell-to-Cell Communication in the Taste Bud: ATP and Acetylcholine as Primary Mediators

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