Calcium Homeostasis Modulator 1-Like Currents in Rat Fungiform Taste Cells Expressing Amiloride-Sensitive Sodium Currents
Calcium Homeostasis Modulator 1-Like Currents in Rat Fungiform Taste Cells Expressing Amiloride-Sensitive Sodium Currents
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DOI：
10.1093/chemse/bjx013
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发表时间：
2017-05-01
期刊：
影响因子：
3.5
通讯作者：
Bigiani, Albertino
中科院分区：
文献类型：
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作者：
Bigiani, Albertino
味觉细胞对盐的接受仍然是发生在味蕾中的较少被了解的转导过程，味蕾是检测食物化学物质的外围感官器官。虽然有证据表明上皮性钠通道(ENaC)作为钠受体发挥作用，但目前尚不清楚盐检测细胞如何将相关信息传递给神经末梢。味觉细胞对甜的、苦的和鲜味的物质作出反应，通过非囊泡机制释放三磷酸腺苷作为神经递质。有三种不同的通道蛋白被认为是ATP分泌的通道：PAnnexin通道、连接蛋白半通道和钙稳态调节剂1(CALHM1)通道。在异源表达系统中，这些通道介导外向整流膜电流，具有不同的生物物理和药理学特性。因此，我测试了感盐味觉细胞是否也被赋予了这些电流。为此，我将膜片钳技术应用于分离的大鼠菌状乳头味蕾中的单个细胞。盐检测细胞通过利用阿米洛利的作用进行功能鉴定，阿米洛利通过关闭ENaCs来诱导电流反应。我使用适当的电压钳制方案和特定的药理工具，寻找是否存在向外整流的电流。我发现，盐检测细胞确实拥有这些电流，其特性与CALHM1通道的存在至少部分一致。出人意料的是，味觉细胞中的CALHM1样电流被已知的pannin阻断剂增强，这表明该蛋白可能对CALMH1起抑制作用。这些发现表明，盐检测细胞和神经末梢之间的通讯可能涉及CALMH1通道释放ATP。
Salt reception by taste cells is still the less understood transduction process occurring in taste buds, the peripheral sensory organs for the detection of food chemicals. Although there is evidence suggesting that the epithelial sodium channel (ENaC) works as sodium receptor, yet it is not clear how salt-detecting cells signal the relevant information to nerve endings. Taste cells responding to sweet, bitter, and umami substances release ATP as neurotransmitter through a nonvesicular mechanism. Three different channel proteins have been proposed as conduit for ATP secretion: pannexin channels, connexin hemichannels, and calcium homeostasis modulator 1 (CALHM1) channels. In heterologous expression systems, these channels mediate outwardly rectifying membrane currents with distinct biophysical and pharmacological properties. I therefore tested whether also salt-detecting taste cells were endowed with these currents. To this aim, I applied the patch-clamp techniques to single cells in isolated taste buds from rat fungiform papillae. Salt-detecting cells were functionally identified by exploiting the effect of amiloride, which induces a current response by shutting down ENaCs. I looked for the presence of outwardly rectifying currents by using appropriate voltage-clamp protocols and specific pharmacological tools. I found that indeed salt-detecting cells possessed these currents with properties consistent with the presence, at least in part, of CALHM1 channels. Unexpectedly, CALHM1-like currents in taste cells were potentiated by known blockers of pannexin, suggesting a possible inhibitory action of this protein on CALMH1. These findings indicate that communication between salt-detecting cells and nerve endings might involve ATP release by CALMH1 channels.