Department of Otolaryngology and Rocky Mountain Taste and Smell Center, University of Colorado-Anschutz Medical Campus, Aurora, USA.
Chem Senses. 2020 May 21;45(4):233-234. doi: 10.1093/chemse/bjaa011.
Among the 5 taste qualities, salt is the least understood. The receptors, their expression pattern in taste cells, and the transduction mechanisms for salt taste are still unclear. Previous studies have suggested that low concentrations of NaCl are detected by the amiloride-sensitive epithelial Na+ channel (ENaC), which in other systems requires assembly of 3 homologous subunits (α, β, and γ) to form a functional channel. However, a new study from Lossow and colleagues, published in this issue of Chemical Senses, challenges that hypothesis by examining expression levels of the 3 ENaC subunits in individual taste cells using gene-targeted mice in combination with immunohistochemistry and in situ hybridization. Results show a lack of colocalization of ENaC subunits in taste cells as well as expression of subunits in taste cells that show no amiloride sensitivity. These new results question the molecular identity of the amiloride-sensitive Na+ conductance in taste cells.
在五种味觉中，盐的味道是最难以理解的。盐味觉的受体、它们在味觉细胞中的表达模式和转导机制仍不清楚。先前的研究表明，低浓度的 NaCl 是通过阿米洛利敏感的上皮钠离子通道 (ENaC) 检测到的，而在其他系统中，ENaC 需要由 3 个同源亚基 (α、β 和 γ) 组装才能形成功能性通道。然而，Lossow 及其同事在本期《化学感官》杂志上发表的一项新研究通过使用基因靶向小鼠结合免疫组织化学和原位杂交技术，检查单个味觉细胞中 3 个 ENaC 亚基的表达水平，对这一假设提出了挑战。结果表明，ENaC 亚基在味觉细胞中没有共定位，并且在没有阿米洛利敏感性的味觉细胞中表达亚基。这些新结果质疑了味觉细胞中阿米洛利敏感的 Na+电导的分子身份。
