Cytochemical Localization of Guanylyl Cyclase Activity in Rabbit Taste Bud Cells

Asanuma, Naokazu; Nomura, Hiromichi

doi:10.1093/chemse/20.2.231

Cited by 13 publications

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“…This suggests that c-AMP and IP3 are distributed not only in the papillae but also in the other tissues. It has been reported that guanylyl cyclase activity is localized in the apical portion of taste cells [9]. From the present results, c-GMP mediates sweet taste transduction and IP3 mediates bitter taste transduction, with salt and sour taste transduction possibly being mediated by other system(s).…”

supporting

confidence: 62%

“…We found that the concentrations of c-GMP were similar in the tongue and fungiform papillae preparations. This finding suggests that c-GMP is concentrated in the fungiform papillae (taste cell) [9]. The concentrations for c-AMP and IP3 found in the tongue and fungiform papillae preparations were, however, different.…”

mentioning

confidence: 82%

“…Although there is much electrical and biochemical evidence for the involvement of second messengers in sensory receptor cells, little is known about the physiology of the cells or the molecular mechanism involved in the sensory transduction process. Several lines of electrical and biochemical evidence indicate the involvement of adenylate cyclase or guanylate cyclase in vertebrate sweet taste transduction [1,5,6,8,9]. Recent electrophysiological studies also suggest that there is a positive correlation between the magnitude of c-GMP activation and the amplitude of the receptor potential induced by sweet taste [1,5].…”

mentioning

confidence: 99%

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Tastes Activate Different Second Messengers in Taste Cells.

Miwa

Kanemura

Tonosaki

1997

The Journal of Veterinary Medical Science

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ABSTRACT. Taste signal transduction occurs in the microvillous membrane of taste cells. Previously, we hypothesized that c-GMP may mediate sweet taste transduction. Some data indicated that IP3 may have a role in vertebrate bitter taste transduction. Here we report that the different second messengers are activated by different tastes. We used techniques designed for radioimmunoassay measurement. The results indicate that sucrose triggers an increase in c-GMP concentration and quinine increases the IP3 concentration in mouse taste cells. These results support the sweet and bitter taste transduction hypotheses. -KEY WORDS: radioimmunoassay, taste cell, taste transduction.J. Vet. Med. Sci. 59(1): 81-83, 1997 pathways in taste cells. Here we report that a sweet taste stimulus raised c-GMP concentration in taste cells, and a bitter one increased IP3 concentration. We examined levels of c-GMP, c-AMP and IP3 with radioimmunoassay kits: that for c-GMP being supplied by Yamasa (Chiba, Japan), and those for c-AMP and IP3 being supplied by Amersham (Arlington Heights, Ill. U.S.A.). The measurements were made according to the manufactures' guidelines [10]. Male mice (Slc:ICR:25-30 g body weight) were deeply anesthetized with an intraperitoneal injection of Pentobarbital sodium (45 mg/Kg). The tongues of the mice were always adapted with DW, so that, the DW stimulus did not change the concentrations of c-GMP, c-AMP and IP3 in the taste receptor cell. DW was used as a control taste stimulus. Relative concentration of c-GMP, c-AMP or IP3 for each taste stimulus was compared with the concentration elicited by DW. The tongue was stimulated with a taste solution for about 10 sec, and the anterior 3 to 4 mm area was removed and immediately frozen. In Fig. 1, the concentration of c-GMP in response to sucrose stimulation was higher than that to DW stimulation (Fig. 1a). In contrast, when HCl, quinine or NaCl was applied to the tongue, the concentrations of c-GMP were similar to that observed with DW stimulation (Fig. 1a). Upon application of quinine, the concentration of IP3 was higher than when sucrose, HCl or NaCl were presented (Fig. 1c). Sucrose, HCl or NaCl produced higher concentrations of IP3 than DW stimulus; however, these changes were always smaller than those produced by quinine. Changes in the concentration of c-AMP produced by the application of DW and the four individual taste stimuli were not significantly different for the different stimuli (Fig. 1b). The tongue preparation contained large amounts of muscle, nerves and other tissues. Muscles and nerves have an abundant supply of c-AMP and IP3, and this may interfere with the measurement of c-AMP and IP3 produced in the taste cells.To overcome these problems, we excised single fungiform papillae from the tongues (50-80 fungiform papillae from two to three mice), using special hand-made forceps. During the surgery, the tongue was continuously stimulated with a taste stimulus solution. When a papilla was excised, it was immediately frozen. The fungiform papilla pre...

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confidence: 62%

mentioning

confidence: 82%

mentioning

confidence: 99%

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Tastes Activate Different Second Messengers in Taste Cells.

Miwa

Kanemura

Tonosaki

1997

The Journal of Veterinary Medical Science

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“…Second, it has been reported that taste buds contain a series of intrinsic molecules participating in the signal transduction cascade involving cyclic nucleotides. These are exemplified by G-protein-coupled receptors (8, 10 -12), gustducin/ transducin (13,14), phosphodiesterase (14,31), adenylyl cyclase/guanylyl cyclase (32,33), and rhodopsin kinase (34). Third, it has been reported that the stimulation of taste cells with some sweet tastants increases their intracellular cAMP level (35).…”

Section: Discussionmentioning

confidence: 99%

Taste Buds Have a Cyclic Nucleotide-activated Channel, CNGgust

Misaka¹,

Kusakabe²,

Emori³

et al. 1997

Journal of Biological Chemistry

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Cyclic nucleotide-gated (CNG) channels have been characterized as important factors involved in physiological processes including sensory reception for vision and olfaction. The possibility thus exists that a certain CNG channel functions in gustation as well. In the present study, we carried out reverse transcription-polymerase chain reaction and genomic DNA cloning and characterized a CNG channel (CNGgust) as a cyclic nucleotide-activated species expressed in rat tongue epithelial tissues where taste reception takes place. Several types of 5-rapid amplification of cDNA ends clones of CNGgust cDNA were obtained with various 5-terminal sequences. As the CNGgust gene was a single copy, the formation of such CNGgust variants should result from alternative splicing. The encoded protein was homologous to known vertebrate CNG channels with 50 -80% similarities in amino acid sequence, and particularly homologous to bovine testis CNG channel and human cone CNG channel with 82% similarities. CNGgust was functional when expressed in human embryonic kidney cells, where it opened upon the addition of cGMP or cAMP. Immunohistochemical analysis using an antibody raised against a CNGgust peptide demonstrated the channel to be localized on the pore side of each taste bud in the circumvallate papillae, with no signal observed for degenerated taste buds after denervation of the glossopharyngeal nerve. All these results, together with the indication that cyclic nucleotides play a role gustatory signaling pathway(s), strongly suggest the involvement of CNGgust in taste signal transduction.

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“…Second, it has been reported that taste buds contain a series of intrinsic molecules participating in the signal transduction cascade involving cyclic nucleotides. These are exemplified by G protein‐coupled receptors,3,5‐7 gustducin/transducin,8,9 phosphodiesterase (PDE),9,18 adenylyl cyclase/guanylyl cyclase,19,20 and rhodopsin kinase 21. Third, it has been reported that the stimulation of taste cells with some sweet tastants increases their intracellular cAMP level 22.…”

Section: Discussionmentioning

confidence: 99%

Molecular Cloning and Taste Bud‐Specific Expression of a Novel Cyclic Nucleotide‐Gated Channel

Misaka

Kusakabe

Emori

et al. 1998

Annals of the New York Academy of Sciences

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Cyclic nucleotide-gated (CNG) channels serve as downstream targets of signaling pathways in vertebrate photoreceptor cells and olfactory sensory neurons. For taste signaling as well, a great deal of information is available predicting the presence of a CNG channel, but no report has been presented on its molecular entity. Here we report on molecular cloning and functional expression of a taste bud-specific CNG channel tentatively named CNGgust. Reverse transcriptase polymerase chain reaction (RT-PCR) primers were synthesized according to some amino acid sequences generally conserved in many CNG channels. RT-PCR was conducted using rat circumvallate papillary mRNA-derived cDNA as a template to obtain positive clones. A corresponding genomic DNA clone was then obtained by screening from a genomic DNA library. Dissecting the entire structure of this gene, we found that the encoding protein had an amino acid sequence similarity of 80% to each of retina and olfactory CNG channels. It was also found by immunostaining with a specific antibody that this gustatory CNG channel (CNGgust) is localized in the tongue and also expressed specifically on the pore side of each taste bud in the circumvallate papillae. Electrophysiological experiments demonstrated that CNGgust resided in a functional state. All these data suggest that CNGgust may be involved in taste signal transduction in sensory cells.

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Cytochemical Localization of Guanylyl Cyclase Activity in Rabbit Taste Bud Cells

Cited by 13 publications

References 0 publications

Tastes Activate Different Second Messengers in Taste Cells.

Tastes Activate Different Second Messengers in Taste Cells.

Taste Buds Have a Cyclic Nucleotide-activated Channel, CNGgust

Molecular Cloning and Taste Bud‐Specific Expression of a Novel Cyclic Nucleotide‐Gated Channel

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