Activation of Polycystic Kidney Disease-2-like 1 (PKD2L1)-PKD1L3 Complex by Acid in Mouse Taste Cells
Activation of Polycystic Kidney Disease-2-like 1 (PKD2L1)-PKD1L3 Complex by Acid in Mouse Taste Cells
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DOI：
10.1074/jbc.c110.132944
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发表时间：
2010-06-04
影响因子：
4.8
通讯作者：
Tominaga, Makoto
中科院分区：
文献类型：
--
作者：
Kawaguchi, Hitoshi;Yamanaka, Akihiro;Tominaga, Makoto
在味蕾所在的四个味觉区域中检测到五种基本味觉（苦、甜、鲜、咸和酸）。虽然检测苦味、甜味和鲜味的分子机制已经很清楚，但对酸味和咸味的分子机制仍然知之甚少。包括酸敏感离子通道在内的几种通道已被提出作为候选酸受体，但它们并不包括体内所有的酸敏感能力。我们最近报道了一种新的酸传感候选者，多囊肾病2样1（PKD 2L 1）-PKD 1 L3通道复合物。该通道不是传统的配体门控通道，仅在去除酸刺激后才门控打开，称为关闭反应。在这里，我们表明，关闭响应酸刺激后，清楚地观察到天然的味觉细胞从轮廓，但不是菌状乳头，谷氨酸脱羧酶67-绿色荧光蛋白（GAD 67-GFP）敲入小鼠，从III型味觉细胞可以可视化，使用钙离子成像和膜片钳方法。在观察到PKD 2L 1免疫反应性的大多数细胞中检测到关闭反应。有趣的是，酸诱发的细胞内Ca 2+增加的pH阈值约为5.0，该值远高于在表达PKD 2L 1-PKD 1 L3复合物的HEK 293细胞中观察到的值。因此，PKD 2L 1-PKD 1 L3介导的酸诱发的关闭反应发生在HEK 293细胞和天然味觉细胞中，表明PKD 2L 1-PKD 1 L3复合物参与体内酸感测。
Five basic tastes (bitter, sweet, umami, salty, and sour) are detected in the four taste areas where taste buds reside. Although molecular mechanisms for detecting bitter, sweet, and umami have been well clarified, those for sour and salty remain poorly understood. Several channels including acid-sensing ion channels have been proposed as candidate sour receptors, but they do not encompass all sour-sensing abilities in vivo. We recently reported a novel candidate for sour sensing, the polycystic kidney disease-2-like 1 (PKD2L1)-PKD1L3 channel complex. This channel is not a traditional ligand-gated channel and is gated open only after removal of an acid stimulus, called an off response. Here we show that off responses upon acid stimulus are clearly observed in native taste cells from circumvallate, but not fungiform papillae, of glutamate decarboxylase 67-green fluorescent protein (GAD67-GFP) knock-in mice, from which Type III taste cells can be visualized, using Ca2+ imaging and patch clamp methods. Off responses were detected in most cells where PKD2L1 immunoreactivity was observed. Interestingly, the pH threshold for acid-evoked intracellular Ca2+ increase was around 5.0, a value much higher than that observed in HEK293 cells expressing the PKD2L1-PKD1L3 complex. Thus, PKD2L1-PKD1L3-mediated acid-evoked off responses occurred both in HEK293 cells and in native taste cells, suggesting the involvement of the PKD2L1-PKD1L3 complex in acid sensing in vivo.