proton current drives action potentials in genetically identified sour taste cells
Five tastes have been identified, each of which is transduced by a separate set of taste cells. Of these sour, which is associated with acid stimuli, is the least understood. Genetic ablation experiments have established that sour is detected by a subset of taste cells that express the TRP channel P...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 51; pp. 22320 - 22325 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
21.12.2010
National Acad Sciences |
Series | From the Cover |
Subjects | |
Online Access | Get full text |
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Summary: | Five tastes have been identified, each of which is transduced by a separate set of taste cells. Of these sour, which is associated with acid stimuli, is the least understood. Genetic ablation experiments have established that sour is detected by a subset of taste cells that express the TRP channel PKD2L1 and its partner PKD1L3, however the mechanisms by which this subset of cells detects acids remain unclear. Previous efforts to understand sour taste transduction have been hindered because sour responsive cells represent only a small fraction of cells in a taste bud, and numerous ion channels with no role in sour sensing are sensitive to acidic pH. To identify acid-sensitive conductances unique to sour cells, we created genetically modified mice in which sour cells were marked by expression of YFP under the control of the PKD2L1 promoter. To measure responses to sour stimuli we developed a method in which suction electrode recording is combined with UV photolysis of NPE-caged proton. Using these methods, we report that responses to sour stimuli are not mediated by Na⁺ permeable channels as previously thought, but instead are mediated by a proton conductance specific to PKD2L1-expressing taste cells. This conductance is sufficient to drive action potential firing in response to acid stimuli, is enriched in the apical membrane of PKD2L1-expressing taste cells and is not affected by targeted deletion of the PKD1L3 gene. We conclude that, during sour transduction, protons enter through an apical proton conductance to directly depolarize the taste cell membrane. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 Edited* by King-Wai Yau, The Johns Hopkins School of Medicine, Baltimore, MD, and approved October 29, 2010 (received for review September 16, 2010) Author contributions: R.B.C., H.W. and E.R.L. designed research; R.B.C, H.W., and E.R.L. performed research; R.B.C., H.W., and E.R.L. analyzed data; and R.B.C. and E.R.L. wrote the paper. |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.1013664107 |