Characterization of bitter taste responses of intestinal STC-1 cells
Characterization of bitter taste responses of intestinal STC-1 cells
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DOI：
10.1093/chemse/bji022
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发表时间：
2005-05-01
期刊：
影响因子：
3.5
通讯作者：
Saitoh, O
中科院分区：
文献类型：
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作者：
Masuho, I;Tateyama, M;Saitoh, O
用钙离子成像技术研究了STC-1细胞对两种苦味剂(变性和咖啡因)的反应，并与蛙皮菌素的反应进行了比较。咖啡因刺激味觉感受器细胞是已知的，但它的信号特性还没有得到很好的研究。STC-1细胞以剂量依赖的方式对这三种分子做出反应，当对变性受体进行逆转录聚合酶链式反应(RT-PCR)时，在STC-1细胞中检测到预期大小的产物。此外，所有三个信号通路都被磷脂酶C(PLC)抑制剂阻断，这表明PLC在细胞反应中发挥了重要作用。为了研究STC-1细胞中G蛋白信号的调控机制，我们用简并引物聚合酶链式反应的方法搜索G蛋白偶联受体激酶，发现GRK2在STC-1细胞中有表达。我们还证明了三种GRK2(GRK2、GRK3和GRK5)在环状乳头中有不同的分布，而在味蕾细胞中只有GRK2存在。最后，我们在SCT-1细胞中过表达GRK2，发现蛙皮素诱导的反应被GRK2强烈抑制，但变性激活的信号转导不受影响。在咖啡因的情况下，只有当细胞被1 mM咖啡因激活时，GRK2的表达才会降低反应。因此，我们认为STC-1细胞是研究苦味信号分子机制的细胞模型，与其他信号相比，STC-1细胞可以揭示咖啡因诱导的信号特性。
Cellular responses of STC-1 cells to two bitter tastants (denatonium and caffeine) were investigated using a calcium-imaging technique and compared with the response to bombesin. Caffeine is known to stimulate taste receptor cells, but the properties of its signaling have not been well studied. STC-1 cells responded to all three molecules in a dose-dependent manner, and when a reverse transcriptase-polymerase chain reaction (RT-PCR) for denatonium receptor was performed, the product of predicted size was detected in STC-1 cells. Furthermore, all three signaling pathways were blocked by a phospholipase C (PLC) inhibitor, demonstrating the essential involvement of PLC in cellular responses. To study the regulatory system of G protein signaling in STC-1 cells, we searched G protein-coupled receptor kinases (GRKs) by the degenerate-primer PCR method and found that GRK2 is expressed. We also demonstrated that three GRKs (GRK2, GRK3 and GRK5) are differentially distributed in the circumvallate papilla while only GRK2 is present in taste bud cells. Finally, we overexpressed GRK2 in SCT-1 cells and found that bombesin-induced response was strongly inhibited by GRK2 but denatonium-activated signaling was not affected. In the case of caffeine, response was decreased by expression of GRK2 only when cells were activated by 1 mM caffeine. Thus, we showed that STC-1 cells emerge as a cell model for studying the molecular mechanism of bitter taste signaling, and could indicate properties of caffeine-induced signaling in comparison with other signaling.