The peripheral taste system is more complex than previously thought. The novel taste-signaling proteins TRPM4 and PLCβ3 appear to function in normal taste responding as part of Type II taste cell signaling or as part of a broadly responsive taste cell that can respond to some or all classes of tastants. This work begins to disentangle the roles of intracellular components found in Type II taste cells (TRPM5, TRPM4, IP3R3) or the broadly responsive taste cells (PLCβ3, TRPM4) in driving behavioral responses to various saccharides and other sweeteners in brief access taste tests. We found that TRPM4, TRPM5, TRPM4/5, and IP3R3 knockout (KO) mice show blunted or abolished responding to all stimuli compared to WT. IP3R3 KO mice did, however, lick more for glucose than fructose following extensive experience with the two sugars. PLCβ3 KO mice were largely unresponsive to all stimuli except they showed normal concentration-dependent responding to glucose. The results show that key intracellular signaling proteins associated with Type II and broadly responsive taste cells are mutually required for taste-driven responses to a wide range of sweet and carbohydrate stimuli, except glucose. This confirms and extends a previous finding demonstrating that Type II and BR cells are both necessary for taste-driven licking to sucrose. Glucose appears to engage unique intracellular taste signaling mechanisms, which remain to be fully elucidated.

中文翻译：

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TRPM4 和 PLCβ3 有助于对一系列甜味剂和碳水化合物的正常行为反应，但味觉驱动的舔葡萄糖不需要 PLCβ3

外围味觉系统比以前想象的更复杂。新型味觉信号蛋白 TRPM4 和 PLCβ3 似乎在正常味觉反应中发挥作用，作为 II 型味觉细胞信号传导的一部分，或作为可对某些或所有类别的促味剂做出反应的广泛反应性味觉细胞的一部分。这项工作开始阐明 II 型味觉细胞（TRPM5、TRPM4、IP3R3）或广泛响应味觉细胞（PLCβ3、TRPM4）中发现的细胞内成分在简短访问味觉测试中驱动对各种糖类和其他甜味剂的行为反应的作用。我们发现与 WT 相比，TRPM4、TRPM5、TRPM4/5 和 IP3R3 敲除 (KO) 小鼠对所有刺激的反应均减弱或消失。然而，在对这两种糖有丰富的经验后，IP3R3 KO 小鼠确实会舔更多的葡萄糖而不是果糖。PLCβ3 KO 小鼠对所有刺激基本上都没有反应，但它们对葡萄糖表现出正常的浓度依赖性反应。结果表明，与 II 型味觉细胞和广泛反应性味觉细胞相关的关键细胞内信号蛋白对于对除葡萄糖之外的各种甜味和碳水化合物刺激的味觉驱动反应是相互必需的。这证实并扩展了先前的发现，即 II 型细胞和 BR 细胞对于味觉驱动的舔蔗糖都是必需的。葡萄糖似乎参与了独特的细胞内味觉信号传导机制，该机制仍有待充分阐明。