Calcium-sensing receptor mediates phenylalanine-induced cholecystokinin secretion in enteroendocrine STC-1 cells
Calcium-sensing receptor mediates phenylalanine-induced cholecystokinin secretion in enteroendocrine STC-1 cells
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DOI：
10.1111/j.1742-4658.2008.06604.x
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发表时间：
2008-09-01
期刊：
影响因子：
5.4
通讯作者：
Hara, Hiroshi
中科院分区：
文献类型：
--
作者：
Hira, Tohru;Nakajima, Shingo;Hara, Hiroshi
l -苯丙氨酸（Phe）在体内和体外刺激胆囊收缩素（CCK）的分泌。然而，产生cck的肠内分泌细胞感知Phe的细胞机制尚不清楚。钙敏感受体（CaR）可以感知氨基酸，并在胃肠道中表达。在本研究中，我们检测了CaR是否在产生cck的肠内分泌细胞中作为Phe受体起作用。在不同的细胞外Ca2+浓度下或用CaR拮抗剂治疗后，在小鼠产生CCK的肠内分泌细胞系STC-1中测量了CCK分泌和细胞内Ca2+浓度对Phe的响应。在超过20 mM时，Phe诱导STC-1细胞剂量依赖性CCK分泌和细胞内Ca2+动员。在3.0 mM细胞外Ca2+存在下，10和20 mM Phe诱导的CCK分泌显著高于正常条件下（1.2 mM细胞外Ca2+）。10或20 mM Phe诱导的细胞内Ca2+动员也通过增加细胞外Ca2+浓度而增强。此外，通过添加细胞外Ca2+诱导的细胞内Ca2+动员被Phe的存在增强。这些结果与已知的CaR性质非常吻合。用特异性CaR拮抗剂（NPS2143）治疗完全抑制ph诱导的CCK分泌和细胞内Ca2+动员的后期。RT-PCR证实CaR mRNA在STC-1细胞以及小鼠肾、甲状腺、胃、肠等其他组织中均有表达。综上所述，CaR作为Phe的受体，刺激肠内分泌STC-1细胞中CCK的分泌。
Intraluminal L-phenylalanine (Phe) stimulates cholecystokinin (CCK) secretion in vivo and in vitro. However, the cellular mechanism by which CCK-producing enteroendocrine cells sense Phe is unknown. The calcium-sensing receptor (CaR) can sense amino acids, and is expressed in the gastrointestinal tract. In the present study, we examined whether CaR functions as a receptor for Phe in CCK-producing enteroendocrine cells. CCK secretion and intracellular Ca2+ concentration in response to Phe were measured in the murine CCK-producing enteroendocrine cell line STC-1 at various extracellular Ca2+ concentrations or after treatment with a CaR antagonist. At more than 20 mM, Phe induced dose-dependent CCK secretion and intracellular Ca2+ mobilization in STC-1 cells. In the presence of 3.0 mM extracellular Ca2+, 10 and 20 mM Phe induced significantly higher CCK secretion than under normal conditions (1.2 mM extracellular Ca2+). Intracellular Ca2+ mobilization, induced by 10 or 20 mM Phe, was also enhanced by increasing extracellular Ca2+ concentrations. In addition, intracellular Ca2+ mobilization induced by addition of extracellular Ca2+ was augmented by the presence of Phe. These results closely match the known CaR properties. Treatment with a specific CaR antagonist (NPS2143) completely inhibited Phe-induced CCK secretion and the latter phase of intracellular Ca2+ mobilization. CaR mRNA expression was demonstrated by RT-PCR in STC-1 cells, as well as in other mouse tissues including the kidney, thyroid, stomach and intestine. In conclusion, CaR functions as a receptor for Phe, stimulating CCK secretion in enteroendocrine STC-1 cells.