A proton current drives action potentials in genetically identified sour taste cells

被引:122
作者
Chang, Rui B. [1 ]
Waters, Hang [1 ]
Liman, Emily R. [1 ]
机构
[1] Univ So Calif, Dept Biol Sci, Neurobiol Sect, Los Angeles, CA 90089 USA
基金
美国国家卫生研究院;
关键词
gustatory; mouse; TRPM5; acetic acid; HCl; RECEPTOR-CELLS; CHANNEL TRPM5; ACID; PH; RESPONSES; PKD2L1; PKD1L3; CALCIUM; PROTEIN; ORIGIN;
D O I
10.1073/pnas.1013664107
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
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.
引用
收藏
页码:22320 / 22325
页数:6
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