title: G-protein-dependent and -independent pathways in denatonium signal transduction.
abstract: To clarify the involvement of G protein in denatonium signal transduction, we carried out a whole-cell patch-clamp analysis with isolated taste cells in mice. Two different responses were observed by applying GDP-beta-S, a G-protein inhibitor. One response to denatonium was reduced by GDP-beta-S (G-protein-dependent), whereas the other was not affected (G-protein-independent). These different patterns were also observed by concurrently inhibiting the phospholipase C beta2 and phosphodiesterase pathways via G protein. These data suggest dual, G-protein-dependent and -independent mechanisms for denatonium. Moreover, the denatonium responses were not attenuated by singly inhibiting the phospholipase C beta2 or phosphodiesterase pathway, implying that both pathways were involved in G-protein-dependent transduction. In the G-protein-independent cells, the response was abolished by the depletion of calcium ions within the intracellular store. These results suggest that Ca2+ release from the intracellular store is an important factor. Our data demonstrate multiple transduction pathways for denatonium in mammalian taste cells.
authors.affiliation: Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan..
authors.forename: Shoko
authors.initials: S
authors.lastname: Sawano
authors.forename: Eri
authors.initials: E
authors.lastname: Seto
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Mori
authors.forename: Yukako
authors.initials: Y
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002469:Cell Separation; D005260:Female; D019204:GTP-Binding Proteins / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D054799:Phospholipase C beta; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013649:Taste; D013650:Taste Buds / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D002118:Calcium; D019204:GTP-Binding Proteins; D007527:Isoenzymes; D054799:Phospholipase C beta; D010727:Phosphoric Diester Hydrolases; D000644:Quaternary Ammonium Compounds; D010738:Type C Phospholipases; C518037:Plcb2 protein, mouse; C043414:denatonium