Characterization of ligands for fish taste receptors
Characterization of ligands for fish taste receptors
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DOI：
10.1523/jneurosci.0651-07.2007
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发表时间：
2007-05-23
影响因子：
5.3
通讯作者：
Abe, Keiko
中科院分区：
文献类型：
--
作者：
Oike, Hideaki;Nagai, Toshitada;Abe, Keiko
味觉感受分子生物学的最新进展表明，在哺乳动物中，异聚体受体T1 R1/3和T1 R2/3分别对氨基酸和甜味剂产生反应，而T2 R是苦味促味剂的受体。在鱼类中也发现了类似的味觉受体，但它们的配体尚未被鉴定。在本研究中，我们进行了一系列的实验，以确定鱼类味觉受体配体。斑马鱼（Danio rerio）的面神经记录表明，鱼感知氨基酸，甚至地那铵，这是哺乳动物和果蝇厌恶的苦味化合物的代表。利用HEK 293 T异源表达系统对斑马鱼和青鳉鱼（Oryzias latipes）中的T1 Rs进行钙成像分析，发现T1 R1/3和一系列T1 R2/3都对氨基酸而不是糖有反应。三重标记原位杂交分析表明，表达T1 R1/3和T1 R2/3s的细胞存在于表达PLC β 2的青鳉鱼味蕾细胞中。使用T2 Rs的功能分析显示zfT 2 R5和mfT 2 R1对地那铵有应答。行为观察证实，斑马鱼喜欢氨基酸，避免地那铵。这些结果表明，虽然可能有一些鱼类特异性的方式来区分配体，脊椎动物可能有一个保守的味觉机制，T1 Rs和T2 Rs的吸引力和厌恶的口味，分别作出反应。
Recent progress in the molecular biology of taste reception has revealed that in mammals, the heteromeric receptors T1R1/3 and T1R2/3 respond to amino acids and sweeteners, respectively, whereas T2Rs are receptors for bitter tastants. Similar taste receptors have also been characterized in fish, but their ligands have not been identified yet. In the present study, we conducted a series of experiments to identify the fish taste receptor ligands. Facial nerve recordings in zebrafish ( Danio rerio) demonstrated that the fish perceived amino acids and even denatonium, which is a representative of aversive bitter compounds for mammals and Drosophila. Calcium imaging analysis of T1Rs in zebrafish and medaka fish ( Oryzias latipes) using an HEK293T heterologous expression system revealed that both T1R1/3 and a series of T1R2/3 responded to amino acids but not to sugars. A triple-labeling, in situ hybridization analysis demonstrated that cells expressing T1R1/3 and T1R2/3s exist in PLC beta 2-expressing taste bud cells of medaka fish. Functional analysis using T2Rs showed that zfT2R5 and mfT2R1 responded to denatonium. Behavior observations confirmed that zebrafish prefer amino acids and avoid denatonium. These results suggest that, although there may be some fish-specific way of discriminating ligands, vertebrates could have a conserved gustatory mechanism by which T1Rs and T2Rs respond to attractive and aversive tastants, respectively.